Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: muerto on December 13, 2004, 01:42:57 PM
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Anybody here read Shaw's "Fighter Combat"?
In this book he talks about an airpseed that is the speed providing the best gain in total energy. I get the impression this is not Vy.
Does anyone know for sure that it is not Vy?
And if it isn't Vy does anyone know how to determine this airspeed for AH aircraft?
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H-M plots for supersonic fighters exhibit fundamentally different operating envelopes than subsonic fighters. The maximum climb performance for both is along the peaks of the Ps curves up to a point. Supersonic fighters have the ability to use a speed and altitude dependent energy-rate profile. Subsonic prop driven fighters do not have this luxury because thrust decreases above Vy airspeed.
The maximum climb profile occurs along the peaks of the Ps curves for a propeller driven fighter, which is Vy. Also, propeller thrust does not increase with airspeed above that for Vy. As such, increasing speeds over Vy airspeed as no advantage. The trick is to determine the Vy airspeed as it changes with altitude.
Well.... you asked.
Regards,
Malta
p.s. glad to see someone actually reads Shaw's "Fighter Combat"
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Just so you know, V-speeds are an invention for aircraft with stinky whistle motors. Prop aircraft usually don't have V-speeds, and those that do were built in the 60s or later. Also, applying Shaw's book takes some doing because none of the AC built before or during WW2 had V-speeds. Some military transports (C46 for one) did have them, but not from official testing. The pilots and crew chiefs got together and figured them out through experimentation. You can find out Vy, Vx, Vr etc... by experimenting on your own in a given aircraft.
BTW, there is no such thing as a "speed providing the best gain in energy." Speed, and thus energy, is gained by adding power or diving. The best gain in energy is accomplished by applying maximum power or diving, followed by bleeding the opponent's speed down through maneuvering. If you tell me which page this is on I can get a better idea of what he's talking about.
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Flakbait [Delta6]
(http://www.wa-net.com/~delta6/sig/lie.gif)
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Flakbait:
Speed is not the same as energy.
Energy = Speed ^ 2 + Alt
HiTech
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Originally posted by flakbait
Just so you know, V-speeds are an invention for aircraft with stinky whistle motors. Prop aircraft usually don't have V-speeds, and those that do were built in the 60s or later. Also, applying Shaw's book takes some doing because none of the AC built before or during WW2 had V-speeds. Some military transports (C46 for one) did have them, but not from official testing. The pilots and crew chiefs got together and figured them out through experimentation. You can find out Vy, Vx, Vr etc... by experimenting on your own in a given aircraft.
Sure they did, they just didn't use that nomenclature to describe them. But you can look in the manual of these planes and find that stuff.
As to the original question, the answer as it relates to AH is Vy. Bob Shaw covered this very topic during his lecture at this year's con.
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Thanks for the replies.
I didn't understand how there could be a more efficient speed than Vy since that happens at L/D Max; I just knew he implied it, I guess it applies to high speed jets as stantond stated.
Bob Shaw covered this very topic during his lecture at this year's con.
I already was disappointed about missing the con, now I'm really depressed.:(
BTW, there is no such thing as a "speed providing the best gain in energy." Speed, and thus energy, is gained by adding power or diving. The best gain in energy is accomplished by applying maximum power or diving, followed by bleeding the opponent's speed down through maneuvering. If you tell me which page this is on I can get a better idea of what he's talking about.
Speed is kinetic energy, total energy is the combination of kinetic and potential as stated by HiTech's formula. Climbing at a certain speed will cause you to gain the highest level of total energy in the shortest amount of time. There are other factors to consider though, especially if Vy is well below the speed that gives a particular aircraft the ability to maneuver effectively.
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If my memory serves...
A climbing profile at a speed slightly higher than Vy would allow for a higher zoom at the end of the climb, possibly creating a higher Ps than a steady Vy climb.
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Originally posted by muerto
Anybody here read Shaw's "Fighter Combat"?
In this book he talks about an airpseed that is the speed providing the best gain in total energy. I get the impression this is not Vy.
Does anyone know for sure that it is not Vy?
And if it isn't Vy does anyone know how to determine this airspeed for AH aircraft?
Here is the way to optimize your energy before a fight…
Picture yourself in the cockpit of a high performance prop fighter, making contact with a distant target. At that point your priority should be to enter the fight with the highest possible energy state in the shortest possible time. You would achieve that by selecting full military power, unloading to zero G, and accelerating in a dive to the best energy transfer speed, possibly losing several thousand feet in the process. You would then begin a climb, not at the best climb speed, but at the speed for best energy transfer. What surprises most folk about this is the initial dive to a higher speed. That is the correct procedure in all fighters, regardless of type, be they subsonic or supersonic jets, or prop fighters, and regardless of altitude, providing you are not at sea level.
To understand why this works, take a look at the diagram below. This diagram shows lines of constant specific Energy (Es) in green and lines of constant specific excess power (Ps) shown in red. If you want to achieve the highest energy state at the greatest rate of energy increase, you need to maximize your Es and Ps at the same time. That can be seen to occur where the P's curves are tangent to the E's curves. The red dotted lines are drawn through all such points and represents the best energy transfer line. So for the fighter I mentioned before starting at position A the pilot should dive until he reaches the speed for best energy transfer at B and then climb at that speed to C.
(http://www.badz.pwp.blueyonder.co.uk/images/energytransfer2.jpg)
The surprising thing to most people is that in order to get to the best possible energy advantage for the fight, you start by diving! You increase speed to a point well above that for minimum drag, or best climb rate. The objective, after all, was not to minimize drag or get to the highest altitude in the shortest time, it was to gain the most total energy in the least time. In WWII vintage fighters, propeller and turbocharged engine combinations were generally designed to give maximum efficiency close to top speed at the critical altitude. So both altitude and airspeed have an influence on the best energy transfer, that’s why the critical altitude also has an influence, depending on where the fight begins. If you start the fight below the critical altitude you could choose to stay below it and follow the schedule from B to D, you will have more engine power and a slightly higher air speed, resulting in closure and better energy transfer. If time permits, and closure isn’t an issue, it is better to climb to point C. If you start the engagement above the critical altitude for your supercharged engine, there is some advantage in beginning a dive towards the critical altitude to increase the available power, resulting in higher specific excess power, and zooming back into the fight using a hook type maneuver which not only optimizes your energy (providing you don’t exceed top speed in the initial stage, after which point further loss of altitude gets you nothing in return) but yields a positional advantage, if the bandit doesn’t use a similar tactic.
The big question is of course, are there any genuine Ps/Es curves for AH2 that will show the best energy transfer speed for some of the aircraft. Well, I was getting around to that, but I’ve just had to re-start producing EM diagrams for the AH2 aircraft (only done five so far). The good news is, that in order to produce the EM diagrams, all the work required to overlay Ps and Es curves is mostly already done, the bad news is that until I’ve produced EM diagrams for more of the AH2 aircraft, I’ve put that sort of thing on the back burner.
Hope that helps…
Badboy
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hope you do not mind Badboy, I cut and pasted this into a file with the pic for help/training purposes to distribute as needed......I kept your name on it as the author as well :-)
this is similar to the Co-E Chase is it not indirectly anyhow?
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Badboy, that is exactly what I was looking for. Well, okay, the actual speeds for each aircraft is "exactly" what I was looking for, but that explanation helps a lot.
Thanks.
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Badboy: Somthing is not making since in you chart, are you missing the time in the energy state change? Because Vy is defenitly the greatest increase in energy over time .
HiTech
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Originally posted by muerto
Badboy, that is exactly what I was looking for. Well, okay, the actual speeds for each aircraft is "exactly" what I was looking for, but that explanation helps a lot.
Thanks.
Yep, and this partly explains why you will often see good pilots diving into the merge prior to an engagement, the natural counter, is to do exactly the same thing, but better. The hook is shown below:
(http://www.badz.pwp.blueyonder.co.uk/images/Hook2.jpg)
That of course is how the Hook works, if you do it against someone who still attempts to pull up into the vertical. It's a shame but many virtual pilots will defeat it knowingly, and the others, just by driving for a head-on shot :)
However, what I often do when I’m some distance away from a fight, and purely due to laziness, is to simply go to auto climb, and then level off for speed prior to a diving merge. I do that partly because I’m a very lazy flyer, and rely on auto everything as much as possible :)
Hope that helps...
Badboy
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I'm confused. I was confused before, and I'm still confused. I alwasy thought that Vy was the answer. Shaw eludes to some other speed, but doesn't really define it in a way that I could understand. Pyro says he heard Shaw talk about it and Vy is it. HiTech says it's Vy. And though I don't know you guys personally, based on what you have created I respect your explanations. But then Badboy brings back an explanation that is similar to what Shaw talks about in his book.
Agggggghhhhhhhhh! head feels like it will explode.:D
Maybe we have two differnent things going on here. It seems to me that Vy is the way to build E most quickly/efficiently during a climb. Is it possible that this other explanation defines the proper way of going from Vy to the speed you need to be at to properly enter a fight? Clearly Vy is much slower than you want to be in most aircraft if you're entering a co-alt fight.
Certainly acceleration is quickest in a zero g wingload condition. (without giving away alt unneccessarily.)
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Below is a post I submitted, but edited by mistake when I replied to Badboy.
Virage, if I'm remembering correctly, Vy happens at an airspeed ever so slightly higher than L/D Max. So maybe the correct statement is that the greatest Ps is gained at a speed slightly higher than L/D Max, or Vy.
I fairly certain of this much, a zoom is a conversion of energy; potential to kinetic or the reverse. So by trading airspeed for altitude you haven't gained energy you've merely converted it (actually you've probably lost some if you had to pull any Gs to do the conversion.)
A climb at any steady airspeed is not a zoom, its the conversion of the energy being released by the burning of fuel into an increased energy state of the aircraft (it's an increase assuming the aircraft is climbing and/or accelerating.)
A climb at a steady airspeed known as Vy is the most efficient way to use the energy released by burning fuel if you look at the climb and/or acceleration as the storage (however temporary) of energy. If I understand correctly.
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Originally posted by muerto
A climb at a steady airspeed known as Vy is the most efficient way to use the energy released by burning fuel if you look at the climb and/or acceleration as the storage (however temporary) of energy. If I understand correctly.
Yep, that’s what classical climb analysis predicts, and that is what HiTech is referring to, but it has long been understood that the classical climb analysis has an embedded inconsistency. Recall that we are led to choose a speed V to maximize the rate-of-climb, at a given altitude h. This analysis is repeated at a sequence of altitudes and the resulting family of best speeds defines a function Vopt(h). As the aircraft climbs and the altitude changes, the choice of best speed will vary according to this function. It's clear then that the resulting speed is generally changing with time V(t) = Vopt(h(t)). Since our choice of speed was based on maximizing the unaccelerated rate-of-climb there is an inconsistency. This was well appreciated in the days before WWII and various “corrections” were suggested. When properly considered, the accelerated rate-of-climb works out to be less than the unaccelerated prediction for best energy transfer. In energy terms it is clear that the aircraft is gaining kinetic energy so that the gain in potential energy is diminished from the earlier estimate and that total increase in energy is what is being optimized on my previous diagram.
Why isn’t all this explained better in classical climb analysis? The piston-powered aircraft of WWII vintage had a limited speed range so that the amount of stored kinetic energy was generally small compared to the potential energy. For example, a speed change from 100 mph to 400 mph requires a certain increase in kinetic energy per unit mass. To achieve the same energy change in potential form requires an altitude increase of about 5000 ft. Thus, a significant change in speed is equivalent, in an energy sense, to a rather modest change in altitude. When you consider that the difference in speeds we are discussing here is very much smaller than that, the resulting change in altitude is even less. For this reason it was mostly okay to just ignore kinetic energy for such calculations. Note, however, that the kinetic energy varies as the square of the speed, doubling the speed will increase the kinetic energy by a factor of four, so as the speed capabilities of fighters increase, the kinetic energy becomes increasingly important, which is why such things are more significant for modern fighters. Although the effect is often ignored in classical climb analysis, the correction ideas noted above were well known in the early 1940's and there is a German report detailing the best energy transfer methods used on WWII vintage fighters by German flight test engineers, which was translated to English in 1944. I also have a document detailing the same theory that was published by the USAF, and despite the fact that the subject is always contentious when posted, the method is correct.
Hope that helps…
Badboy
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Badboy, I Belive I know what your refering to, but gut feel tells me we are talking about somthing with in the 5mph different range.
HiTech
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Very nice explanation Badboy!
So, by diving below the critical altitude for the merge and crossing through it as you zoom post-merge, you're in effect maximizing your energy state by remaining at the critical alt for the longest period of time... a sort of average half below the crit alt and half above the crit alt... is that correct? Also, the critical alt is the most efficient altitude for fuel consumption/cruising speed/energy efficiency (in level flight) for said aircraft?
Diving/climbing through this critical altitude will give you more overall energy when compared to simply climbing (without the dive).
"Almost" like a slingshot... ? Or a roller coaster with an energy deposit at the bottom. (weird analogies that only make sense in my head :cool: )
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Every time I figure I'm simply going to quit surfing the boards, something like this comes along.
Didnt realise the Energy = Speed ^ 2 + Alt thing, damn that really puts things in perspective. I've been frikkin clawing for altitude...
Now that I see the diagram, I recognise that hook maneuver too. I get the impression jugs are really good at that type of thing, they don't turn, but they sure as hell can corner.
Thanks all,
Scherf
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Hi Badboy,
>Yep, that’s what classical climb analysis predicts, and that is what HiTech is referring to, but it has long been understood that the classical climb analysis has an embedded inconsistency.
I'm aware of that, but I'm not sure it makes any difference for the climb speed.
I just ran some numbers: Climbing at optimum steady-state climb speed, my WW2 fighter of choice needs 301 s to 4400 m. Optimum climb speed varies by +/-5 km/h indicated air speed in the interval (dropping from sea level to altitude). The energy needed for accelerating to the lower indicated but higher true climb airspeed I fail to include in my calculation is equivalent to 56 m altitude, which is equivalent of another 4 s of climbing. (That's the classical error.)
However, the climb speeds themselves don't seem affected by that error - on the contrary, if I use a constant climb speed the energy gap widens (insignificantly).
Altering speed from the steady-state climb speed only seems to give an advantage if you go slower, else the energy gap increases. However, I can gain only 2 s of the abovementioned 4 s because I have to fly at stall speed at least, and that will give me a 60 s steady-state climb time penalty so it's not really an improvement.
The document you mentioned may have some significance, but I've got to admit that I don't get it :-)
Regards,
Henning (HoHun)
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Originally posted by HoHun
Hi Badboy,
The document you mentioned may have some significance, but I've got to admit that I don't get it :-)
Regards,
Henning (HoHun)
Hi HoHun
Firstly, let me apologize for the following verbosity… I know I could explain this to guys like yourself and HiTech much more briefly than I’m going to, but I’m going to take the opportunity to get back to basics in the hope I can also open the subject to some of our less technically minded friends. Here goes…
It seems to me as though there are two different discussions here, one regarding best climb rate, and the other about best energy transfer rate, and they are absolutely not the same thing. Let me see if I can explain it a little better. Being in the best possible situation for an engagement, isn’t just about getting as high as possible in the shortest time, if it was, we could simply use our maximum climb rate to get as high as possible as quickly as possible and the problem would be solved. However, there are four vitally important energy related characteristics that need to be optimized to give a pilot the best possible chance of winning a fight, of which the climb rate solution only nets two of them, so in effect, solving the best climb rate problem only gets the job half done. The theory for finding the schedule for best energy transfer depends on optimizing the Es and Ps at the same time, so I’d better explain those terms:
Specific Energy:
Total energy by itself is not an accurate measure of maneuverability because of the inertia associated with weight. A B-17 weighing 40,000lbs may have more energy than a P-51 at 10,000lbs but the P-51 is clearly more maneuverable. A more accurate indication of maneuverability is the total energy divided by the gross weight to determine the energy per pound of weight, this is called the Specific Energy and is given by the expression Es = V^2/2g + h where V is the speed, g is gravity and h is the altitude, and is measured in units of length (feet say). Notice that the velocity is a significant part of this expression, having the best Es is not just about getting as much altitude as possible in the shortest time, it is about getting the best combination of speed and altitude. But that’s not all because getting to a fight with more altitude than your opponent isn’t any good if you don’t have the maneuverability to capitalize on it, which leads us to:
Specific Excess Power
The rate of change of energy with respect to time is called power, but once again, our B-17 with its four magnificent engines has more power than our P-51, but it still isn’t more maneuverable, so once again we are primarily interested in specific power, which is power divided by weight. Of course we are also only interested in the useful power, free to be used to maneuver, and this is called the excess power, that power left over once drag has been overcome. So we arrive at the specific excess power, or Ps and it is given by the expression Ps = V/g dV/dt + dh/dt which is the velocity divided by gravity, times the rate of change of velocity with time, plus the rate of change of altitude with time.
So, putting all this together, we need to find a way of optimizing four terms all at once, they are the four terms that comprise the Es and Ps expressions above. We need to find the best possible combination of velocity, rate of change of velocity, altitude and rate of change of altitude, all at the same time! It is the fighter pilots equivalent of nirvana, the mother of all sweet spots!
By climbing to an engagement at the best climb rate, you are only optimizing two of those terms, the altitude and the rate of change of altitude, but that’s only half the story… it simply won’t cut it. If you ignore the other two terms, you may arrive at the fight with a little more altitude, and a better climb rate, but you simply won’t be in the best energy situation for the ensuing engagement, you can only find that sweet spot by optimizing the Es and Ps together and those considerations push up the airspeed beyond that required for the best climb rate alone… That’s what I’ve tried to illustrate in the diagram I posted, I have never been talking about just getting as high as possible as quickly as possible, even though that can be a simple and effective strategy to use in the arena if you have a plane that can do it really well (the G10 springs to mind) but in terms of correct air combat, it simply isn’t the right thing to do, as almost any current fighter pilot will confirm.
Hope that helps…
Badboy
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Hi Badboy,
I think your E diagram is quite sensible - for going from A to D most quickly, A->B->(just short of) C->D looks like the optimum.
However, numerically I'd say that your speed B->C is much too high as it would be far above Vy for a typical WW2 propeller fighter. Your preference of speed for best energy transfer seems to confirm that you've selected a different speed on purpose. (A->B would be almost invisible on my variant of the chart :-)
At Vy, I've got Psmax for 1 G - it's the optimum speed to maximize energy and has a defined technical meaning.
Is there such a defined meaning for the speed of best energy transfer as well? It seems to me that you're thinking of a concept of a similar nature as corner speed ...
Regards,
Henning (HoHun)
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Great Post, Badboy!
That goes right along with what some of the veterans have been telling me. They did not use the "best climb rate".
No disrepect to them is intended in this statement but many of them do not know very much about aerodynamics. They were combat pilots and not engineers.
The general rule was to climb with enough speed to do a loop over the top if you had too. Not very scientific but seems to go right along with the gist of your post.
Crumpp
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Drag, Lift, gravity, and thrust contribute to change where one plane is relative to another plane in time.
Drag resists movement.
Gravity accelerates objects in one direction.
Thrust and lift force the plane in specific directions.
Drag is minimized when the plane is unloaded.
So, if the plane spends a minimum time in an unloaded state where the force of drag is minimized such as an unloaded dive followed by a hard turn to an unloaded climb then will the plane gain an overall energy advantage over a plane flying at a constant best climb speed in the same amount of time?
Plane A is the diving and climbing plane.
Plane B is the constant best climb speed plane.
Both plane A and plane B have the same amount of gravity forced upon them except I think the plane spending more time higher has a slight advantage.
Both planes have a similar amount of thrust from the engine during the time period except some differences associated with efficienies at different altitudes and speeds.
Plane B has a consistant force of lift and drag applied except this relationship does change some with the change of altitude.
Plane A spends an amount of time where drag is minimum and an amount of time where the force of drag is high.
So, does Plane A gain more or less total energy compared to plane B?
I think this is a very interesting question because certain planes inevitably were better at pushing the numbers in favor of gaining energy during unloaded flight, better in dives and zooms than other planes and these particular attributes contributed to enable one plane an advantage over another plane when utilizing dives and zooms in close in, one on one dog fights.
Also, Plane B goes from the starting point to the ending point in a straight line and therefore goes the shortest distance from the starting point to the ending point.
Plane A turns during the flight time and therefore has to go a longer distance if the ending point is common to the ending point of plane B.
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Great posts Badboy. This explains a lot of the questions I had. I knew Vy seemed sort of right, but I also knew entering a fight a Vy is a bad idea.
Is there any kind of rule of thumb one can use to determine the speed that can put you in the sweet spot?
Is there a correlation to Vy (a percentage of Vy perhaps) or anything simple like that, or does it depend on too many factors to have a general rule of thumb to shoot for?
Crumpp said:
The general rule was to climb with enough speed to do a loop over the top if you had too. Not very scientific but seems to go right along with the gist of your post.
and this goes along with what I was trying to say before (what I was trying to interpret from Shaw's book and my own experience in AH) that you need to be at manuvering speed at the engagment, not at Vy.
I think Shaw calls it vertical manuvering speed, then says something like (its been a while since I read it) whenever possible go to best energy speed (when the bogey is not in guns range or not in a position for a guns solution) and climb, but be able to have vertical manuevering speed while closely engaged.
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One thing that becomes obvious when thinking about this puzzle involves technique.
In order to illustrate this point please consider reading the following personal experience.
My brother allowed me to pilot his plane and he wanted to see if my pilot simulation experience helped. He challenged me to get the plane at a higher level speed. My efforts resulted in about 30knots less than he was able to get. I tended to overcontrol. The plane spent too much time flying sideways under my ham fisted piloting whereas my brother managed to keep the plane relatively arrow straight.
Application:
If Plane A were flown from point A at 10,000 feet to point B at 15,000 feet in a straight line that happened to be at a climb angle corresponding with the planes best climb speed then this plane would be converting the power of fuel into the power of altitude in the most efficient manner possible. As long as the pilot managed to keep the plane arrow straight without it yawing sideways, pitching forward, or back; then no other pilot could possibly get the same plane from point A to point B any faster; all else being equal.
Correct?
What if pilot B is flying side by side with plane A at point A in the same plane at the same starting speed and:
The pilot of plane B pushes the stick forward hard enough to create lift with the elevator that causes drag and this control input rotates the plane's pitch nose low and even starts causing the main wing to create lift on the bottom surface again creating more drag. The ham fisted pilot then allows the plane to speed up but by now the plane is pitched into a very steep dive. He pulls back on the stick to make the dive less shallow, after all he is in a race with pilot A to point B, and point B is higher than the starting point at point A. As soon as pilot B settles into a constant dive angle he starts pulling back on the stick to climb into a zoom climb by pointing his plane at point B somewhere ahead of plane A. Pilot B spends the rest of the time it takes to reach point B pitching his plane up, pulling gs, and creating drag.
Which plane reaches Point B first?
Which plane has more energy at the time the first plane reaches point B?
Looking at the problem from this angle is similar to looking at the race between my brother and me in his plane.
How can drag be minimized?
Back to pilot B starting at point A both side by side, both flying at the same speed and angle (best climb speed, best climb angle):
Pilot B pushes the stick forward only enough to unload as much G force as possible. Plane B is now on a ballistic trajectory determined by engine thrust, gravity and momentum. All forms of lift and therefore drag are canceled out to their minimums.
Plane B remains on this trajectory for just the right amount of time before pulling into a zoom climb at just the right time to, again, minimize drag during the vector change at the wings most efficient speed and corresponding g load. The vector change is made just so as to allow the pilot to return to an unloaded ballistic trajectory that will cause his plane to arrive at point B.
Now which plane arrives at point B first and which plane has more energy at the time both planes arrive at point B?
What if pilot A is using his rudder pedals as foot rests?
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But the original question was not in regard to entering combat, it was simply asking at whether the best speed to gain energy was Vy.
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Pyro Said:
But the original question was not in regard to entering combat, it was simply asking at whether the best speed to gain energy was Vy.
True, true, true.
And I think Vy is the correct answer to the original question I asked.
It just so happens that, in my head, there was a lot more to the question than what I actaully asked.
Shame on all of you for not being mind readers.:rofl
But because of what has come out in this discussion I have gained a greater insight into the overall question I sought to have answered and I thank you all.
The only thing lacking now is knowing the acutal speeds for each aircraft (not Vy, but the best energy transfer speed to fit into Badboys diagrams) or knowledge of how to determine it purely from flying the aircraft.
That, and the ability to instantly judge a con's relative energy state, and the skills to perfectly execute the proper judgement with regards to the correct tactics to apply based on any given situation, and... etc, etc,...
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Originally posted by Pyro
But the original question was not in regard to entering combat, it was simply asking at whether the best speed to gain energy was Vy.
I thought the original question was about a comment Shaw made in his book about “maximising the rate of total energy gain rather than just the rate of climb” Shaw’s comment is in the context of air combat. I assumed that getting an insight into air combat was the real motivation behind the questions being asked... Just trying to be helpful here, didn't mean to hijack the thread.
Badboy
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It's certainly not a hijacking. I just think the original question was just being interpreted differently by various parties which was causing some confusion.
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I agree, no hijack at all.
I'm very glad you chimed in, Badboy, because without your post I would have recieved the answer to my initial quesiton, but I still would have had more unresolved questions about Shaw's mention of Best Energy" speed.
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Hi Badboy,
>Shaw’s comment is in the context of air combat.
After re-reading Shaw, I'd say the speed of best energy transfer is only relevant for supersonic jets that have a superior climb ability above Mach 1 than below in parts of their envelope. Wow! :-)
Regards,
Henning (HoHun)
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HoHun: Isn't close to constant thrust cool.
HiTech
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Originally posted by HoHun
Hi Badboy,
After re-reading Shaw, I'd say the speed of best energy transfer is only relevant for supersonic jets that have a superior climb ability above Mach 1 than below in parts of their envelope. Wow! :-)
Regards,
Henning (HoHun)
I can see how you could get that impression if you only read Shaw, and he actually says about subsonic aircraft, that only slightly faster speeds result. However, the theory works, and the equations posted earlier are equally applicable, regardless of the aircraft’s top speed. It just becomes more important as the speed range increases. There are other sources from 1944 onwards that apply the techniques to high performance prop fighters, and it is relatively easy to develop the details of the theory, apply it to curves generated for WWII fighters and confirm it for yourself. If you need more mathematical or aerodynamic detail, check this source: http://aerade.cranfield.ac.uk/subject-listing/esdu/ES161.html most of those documents are available in their entirety from any good university library, providing they have an aeronautics department. However, these documents, have been written in the context of modern jet aircraft, but the methods are easily adapted. Good luck with that :)
Badboy
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Muerto et al,
Sounds like to me most of you are in violent agreement on this topic. Let me try to clear it up...since apparently I started it. ;)
The best speed for "long-term" energy addition is Vy, best climb rate speed, best energy-addition rate speed...whatever you want to call it...it's the same thing. I think one thing that's confusing some folks is that Vy is not a single number, but varies with altitude for a given aircraft (also weight, configuration, etc.). The dotted line from points B to C in Badboy's Ps chart is actually Vy for this aircraft.
So if you want to gain total energy as fast as possible over a long period of time (we're not talking seconds here, necessarily), get to Vy as quickly as possible (dive if you're slower, zoom if you're faster), then climb at Vy until it becomes more important to do something else (rather than gain energy), like shooting somebody.
Hope this helps rather than making things worse.
cheers,
Robert Shaw (Mouse)...no, you haven't seen me online
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For those of us non-pilots who haven't a clue what 98% of this thread is all about, I found this webpage to be very helpful!
http://www.av8n.com/how/htm/energy.html#sec-energy-strategy (http://www.av8n.com/how/htm/energy.html#sec-energy-strategy)
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Originally posted by Shaw
Hope this helps rather than making things worse.
Welcome to the boards!
Make yourself at home, the beer is free here :)
Badboy
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Originally posted by MOSQ
For those of us non-pilots who haven't a clue what 98% of this thread is all about, I found this webpage to be very helpful!
Hi MOSQ,
Link doesn't work for me.
Badboy
Edit (Ahh it's John Denker's "See How It Flies" perhaps he's moved it?)
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The Author of the Bible?
Rejoice!
I wish to take this opportunity to express my gratitude for such a valuable resource of information and entertainment.
"Fighter Combat" is awesome.
Thank you very much for a fine literary work, Robert L. Shaw.
I have found the sustained turn technique to be especially useful and enlightening.
Is it possible that you are inclined to converse on the finer points of Air Combat? Will you entertain a few questions?
Joe
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Sounds like to me most of you are in violent agreement on this topic. Let me try to clear it up...since apparently I started it.
Thank you for the clarification; nothing like getting it direct from the source.
Loved the book!
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Originally posted by Shaw
Hope this helps rather than making things worse.
Just to round it off with an example then, suppose you want to get from some speed and altitude at point A, and enter an engagement at a higher speed, say your corner velocity, at a higher altitude, say point D in this diagram.
(http://www.badz.pwp.blueyonder.co.uk/images/energytransfer3.jpg)
And you want to do it as quickly as possible…You would dive to point B, climb to point C gaining speed on the way, then dive again to point D.
The initial dive, followed by a climb in which you gain speed, followed by a diving entry into the fight, is what I’ve been describing all along.
Hope that helps…
Badboy
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Hmmm, it works when I click it, try: http://www.av8n.com (http://www.av8n.com)
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Originally posted by JG14_Josf
I have found the sustained turn technique to be especially useful and enlightening.
Joe
Be careful though Joe, the best sustained turns are very different things in Jet and Propeller driven aircraft. In a Jet the maximum sustained turn rate is generally well above the stall speed, and often closer to the corner velocity, while on a prop’ the best sustained turn occurs on the edge of the stall. This diagram shows why…
(http://www.badz.pwp.blueyonder.co.uk/images/PropvJet.jpg)
You can see here, the reason is the shape of the Ps = 0 curve is very different between Jets and propeller driven aircraft. Even the mighty F-16 that can sustain 9g, has a Ps = 0 curve that drops dramatically below corner speed, while most prop’ fighters have a zero Ps curve that rises all the way to the stall. If you fly a jet at its best sustained turn rate, you need to stay above the stall, often close to corner velocity, when you want to get the best sustained turn out of a prop’ fighter, you fly it right on the edge of the stall.
Hope that helps…
Badboy
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Badboy,
I'm not sure where you are going with the Jet vs Prop comparison but the sustained turn technique described in "Fighter Combat" serves me quite well in WWII combat simulation.
The reason why the sustained turn technique works so well has to do with preying on other player’s weaknesses, particularly their overconfidence. When fighting against opponents with an obvious turn advantage the tendency is for them to go for the angles and burn up their energy.
The sustained turn technique is excellent for developing a sense for relative energy states too.
Also the sustained turn technique is a staple in team tactics allowing the dragging plane to set up his wingman for a good shot without too much risk.
After a successful application of the sustained turn technique the relative energy gains may not be enough to afford a reverse yet have plenty of room to invite the target in for a chase. Being well out of range the game is really on, if the victim takes a bite.
Some times my energy margin is enough to afford plenty of room to pitch back on top of the target but the set-up is so well done it is more fun to just watch the target hang there as my wingman picks him off like a fish in a barrel.
What really interests me about this technique concerns relative energy modeling in the games. Just how much energy loss is accurate during high g turns relative to less aggressive turning?
Which planes were better at unloaded acceleration and are these planes being modeled correctly?
The other game has moved from a condition of relative modeling where acceleration was a generic factor. During those days the energy fight was relatively non-existent. The game was hit and run for those planes that were modeled with inferior turn performance and that was about it. What surprised me was that the sustained turn technique did work then if the other pilot really took the bait and pulled on the stick. Then it was a real trick however to end up with enough energy to zoom and pitch back. Now things are much different, even the P-47s are sticking around to fight it out.
I don’t really know how accurate all this is, but my guess is that if the tactics worked in the real world and they work in the simulation then things are pretty close.
So the question is: How did things work in the real world?
Well...?
I can read "Fighter Combat"
or
Boyd, Galland, Buchner, Stienhoff, Brown, Lipfert, Knoke, etc.
Which book will give me the best picture of how Air Combat was conducted in real life during WWII?
How about this one:
“Actual combat accounts of the successful use of energy tactics are rather rare, but the following example is a beauty. Here John Godfrey's P-51B Mustang has probably 20 percent lower wing loading than the German Focke-Wulf 190D-9 opponent, and Godfrey increases his turn advantage further by skillful use of flaps. The Focke-Wulf, however, may have 20 percent better power loading. Here are two masters at work.
“A plane was approaching, and because of its long nose I thought it was a Mustang. Turning into it I received a shock; it was neither a Mustang nor an ME-109, but a new Focke-Wulf; its long nose was the latest improvement of the famed FW. These planes with the longer noses were rumored to have more horsepower than their predecessors, and were capable of giving a Mustang a rough time. We met practically head-on and both of us banked our planes in preparation for a dogfight.
Around and around we went. Sometimes the FW got in close, and other times, when I'd drop my flap to tighten my turn, I was in a position to fire - but the German, sensing my superior position, kept swinging down in his turn, gaining speed and quickly pulling up, and with the advantage in height he would then pour down on my tail. Time was in his favor, he could fight that way for an hour and still have enough fuel to land anywhere below him. I still had 400 miles of enemy territory to fly over before I could land. Something had to be done. Throwing caution to the wind I lifted a flap, dove and pulled up in a steep turn, at the same time dropping a little flap. The G was terrific, but it worked, and I had the Jerry nailed for sure. Pressing the tit I waited, but nothing happened, not a damned thing. My guns weren't firing."
"By taking this last gamble I had lost altitude but had been able to bring my guns to bear while flying below the FW. With his advantage of height he came down, pulled up sharp, and was smack-dab on my tail again. The 20mm. cannons belched and I could see what looked like golf balls streaming by me. A little less deflection and those seemingly harmless golf balls would have exploded instantly upon contact with my plane. "Never turn your back on an enemy" was a byword with us, but I had no choice. Turning the plane over on its back I yanked the stick to my gut. My throttle was wide open and I left it there as I dove. The needle stopped at 600 miles per-that was as far as it could go on the dial. Pulling out I expected at any minute to have the wings rip off, the plane was bucking so much. The last part of my pull-up brought me up into clouds. I was thankful to have evaded the long-nose FW. for that pilot was undoubtedly the best that I had ever met." (Fighter Combat, Robert Shaw)
Note how the tactics are explained with specific examples.
Where are you going to find this type of instruction, this type of historical documentation made relative to specific tactics and maneuvering for WWII fighter planes no less!?
It doesn’t stop there in “Fighter Combat”.
How about the Split, Half Split, Sandwich, Brackett?
What about the Bogie Cloud? No that sounds familiar in WWII combat simulation.
OK, enough with the sales pitch. I am a fan. I am curious too.
Joe
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Here John Godfrey's P-51B Mustang has probably 20 percent lower wing loading than the German Focke-Wulf 190D-9 opponent, and Godfrey increases his turn advantage further by skillful use of flaps. The Focke-Wulf, however, may have 20 percent better power loading. Here are two masters at work.
Pretty sure that was NOT a Dora. None were inservice at the time and it is very unlikely Godfrey ran into a prototype from Rechlin on a test flight. Allied intelligence knew about the Dora and had been hyping it up for about a year before it was deployed.
Most likely he just ran into a skilled pilot in an FW-190A.
Crumpp
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Crumpp,
Unless more information is identified concerning that particular historical account then my question is: who is going to be the best one to guess which planes were involved?
My money is on the guy who actual saw the enemy plane and who actually flew the plane involved in the fight, the same guy who probably has better vision than 90 percent of the population.
That however is a minor point when compared to the message found within the text.
Here is where I am beginning to find a problem with your messages. Do you have anything to say?
Chances are that I will eagerly buy your book. I am currently able to afford investments in literature. Here is a real gem: “The Gulag Archipelago” by Aleksander Solzhenitsyn.
Now there is a guy with a message.
If the subject matter that one wishes to digest concerns a more specific realm of human activity then there is my all time favorite ‘airplane’ book: “Boyd” by Robert Coram.
If you don’t find “Boyd” to be entertaining, insightful, and inspiring then perhaps there is little value for you in literature, perhaps it is just my awkward sense of value.
The message in “Fighter Combat” is specific. The questions answered are specific:
”How to” fight air combat. Which specific performance attributes lend themselves toward specific tactics and specific maneuvers?
X percentage of Y performance advantage can be applied like so…
The message is valuable to some because the information, the instruction, and the knowledge works in simulated air combat. If you read the bacl cover of “Fighter Combat”, if anyone is to believe the words coming out of the mouths of WWII fighter pilots (I know this is not a popular opinion among the players of games i.e. Who is so stupid as to believe pilot anecdotes. What a joke!) then the message found in “Fighter Combat” is useful in real life too.
The message, if found, is a common understanding of stuff. How can one put this into words? I guess that is the problem isn’t it?
Communication is finding what is common between the one telling the message and the one listening to the message.
Note: two things have to occur; the one telling must tell and then another one must listen.
What an incredible task! No only does one have to form a message in a way that can be heard but another one has to open their minds and allow the message to enter. I guess ignorance is a virtuous sort of thing.
If you get a chance to read about Solzhenitsyn’s Gulag then perhaps you will understand my outburst here and forgive me some. I do hope to find a message within your upcoming book. I wish only to communicate and my abilites are lacking. I have these damn chips on my shoulders and it is not easy to ignore them.
Joe
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Jesof,
Fighter pilots make ID mistakes all the time. It's a fact of life.
When did Godfrey's unit give up it's P51B's?
When did the FW-190D9 enter service with the Luftwaffe?
What is more likely? The Luftwaffe had a lone FW-190D9 in service that happenend to encounter Godfrey's P51B or that he misidentified the aircraft?
That however is a minor point when compared to the message found within the text.
Exactly. Was I supposed to explain that?
Sorry!!
Crumpp
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What is more likely?
I placed my bet.
What is the point of such scrutiny? Is this a simple matter of accuracy in journalism or is there another reason for this need to identify the FW in question, the date of the fight, or any other specific detail?
If the idea is to be accurate then by all means identify the planes involved. If the best that can be done is to calculate internment dates against production dates and then the results still allow for the event to hold true then what has been done? Has accuracy been served to communicate your opinion?
Is that it?
Please don’t read anything in between the lines. I am asking a simple academic question. Is that the extent of your message concerning my attempt to communicate what I consider to be valuable information concerning our common interest i.e. WWII air combat?
My opinion is that the message found in those words is valuable because it is accurate specific to the application of tactics in air combat relative to specific performance capabilities. If your contention is limited to the possible error concerning the identification of a specific plane model and if there is no new information that can accurately identify the error then thanks for the effort.
Is this the extent of our communication?
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this started out as a great thread! ya'll should switch emails :)
with that said, if it was a Fw190A8 verses a P51B
or a Fw190D9 vs a P51D it all really wouldn't matter unless the game you flying is as accurate as the real life counter parts........so it could matter to a degree depending on how well the flight sim you are transfering this knowledge to is designed to being close to the real thing.......
the differences in the P51B and P51D as well as the FW190A8 and the FW190D9 are quiet unique so if you are trying to take the thread you quoted and put it toward flying against said aircraft in the game, if the aircraft are mis identified you would be in for a surprise, maybe for the good maybe for the worst.....
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another reason for this need to identify the FW in question, the date of the fight, or any other specific detail?
Yes.
Examining the aircraft backs up some documentation I have and might help complete a puzzle.
My opinion is that the message found in those words is valuable because it is accurate specific to the application of tactics in air combat relative to specific performance capabilities.
Exactly. This encounter does represent one of the very few anecdotes of USAAF aces running into experienced Luftwaffe pilots. The more details, the more we learn from it.
You have to understand that the vast majority of the Luftwaffe the USAAF encontered were not trained well enough to make any kind of air to air combat comparision based off of aircraft performance.
Here we do see two master's at work and specific aircraft performance is a factor. It is even more significant once the correct opponents are identified. Expecially since this is exactly the manner Experten Luftwaffe FW-190A8 pilots relate they fought their aircraft with great success against the P51.
With that said It is not my intention or desire to hijack. This is a great thread and I think Identifying the opponents adds to it. The more "known's" we have the more accurate our predictions.
Crumpp
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Originally posted by JG14_Josf
I'm not sure where you are going with the Jet vs Prop comparison but the sustained turn technique described in "Fighter Combat" serves me quite well in WWII combat simulation.
Hi Joe,
Just trying to be helpful here… There is a lot of information to be found on sustained turns, and a lot of it comes from the perspective of modern air combat, so when you actually try to figure out how to perform an optimum sustained turn, in a practical sense, information can be misleading. Sources might advocate rules of thumb, such as maintaining a speed close to corner velocity, which is good advice in a Jet, because the sustained turn rate can drop rapidly below that speed. But the best sustained turn rate for a prop fighter occurs well below corner velocity, at the edge of the stall, where most Jet’s would be wallowing well below their best sustained turn rate.
For example, Shaw says in his book that "the minimum sustained turn radius is normally achieved at fairly slow airspeed, considerably slower than for best sustained turn rate." and you can see from the EM diagram I posted, that is true for the Jet, (shown in red) where the best sustained turn radius occurs at a much lower speed than the best sustained turn rate. However, that’s not so true for propeller driven fighters, the difference is very much smaller, and for practical purposes the best sustained turn rate and radius are at the same point in the envelope, on the edge of the stall. That’s an important distinction that often gets missed when these ideas are translated into the geometry of air combat, so I was just pointing it out in my previous post in an attempt to be helpful.
Badboy
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Rule of thumb 2.5 g stall speed for sustained turns.
HiTech
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Crumpp,
If the error can be identified then please do so, otherwise your guess must be weighted against the guess of a guy who is claiming to have actually been there and therefore his opinion is somewhat more valuable than yours in my opinion. Am I being unreasonable?
The accuracy of identifying the plane type is secondary if the idea is to understand the tactical application of maneuvering based upon performance variables, which is the reason why I posted the quote.
The quote is not simply a pilots account of a specific engagement, rather it is an example illustrating ‘how to’ employ tactics based upon specific performance advantages.
Is this not valuable information? Is this information not germane to the topic?
Is it more important to identify a specific plane with a 20 percent wing loading advantage over another plane with a 20 percent power loading advantage than it is to identify the tactics that work and do not work as these performance advantages are pitted against each other?
I think, as far as the quote from “Fighter Combat” goes the important information concerns the application of tactics and maneuvering relative to variations in performance capabilities and that is why I posted the quote. To me the identity of the planes involved is secondary and therefore I see no reason to spend a whole lot of energy and time trying to refute the stated observation. If there was a mistake it matters not to the nature of the information in consideration.
One plane employs an acceleration advantage to extend into vertical capability, while the other plane uses a wing loading advantage to gain angles. Dog fighting (according to this type of information) included more than a simple matter of pulling on the stick to get on the opponents tail. A plane with an advantage in power loading could extend from an opponent in a diving turn and in the process gain a sufficient advantage in energy to reverse into position from defensive to offensive, from being in front to being in the rear hemisphere of the plane with the wing loading advantage. The distinction is being made as to what performance advantages lend themselves to which tactics. Powerloading (which is a qualified term in the Book) supports energy tactics while wing loading advantages tend to support angles tactics.
This distinction supports the claim that dog fighting does not require turn performance advantages.
If this is true, that dog fighting can be conducted by an inferior turning plane against a better turning plane by using energy tactics then there is value in figuring out at which speed one plane with gain energy over another plane.
Is it possible that the better power loaded plane in the example unloaded his plane in his diving turn, that the FW pilot reduced drag in an effort to gain relative energy?
Is it then possible that the FW pilot made an efficient turn to zoom his plane on a heading that would again unload his plane to minimize drag?
Did the FW pilot just go to his best relative energy gaining speed and then sit back and wait for the expected results?
My efforts are aimed at understanding Air Combat.
Games are fun and sometimes they manage to pass as a reasonable simulation from my perspective. But what do I know?
I prefer to defer to those who are more likely to know, those who have sat in those planes and those who have been required to fight for their lives.
What does it matter if my opinion is in error? Being ignorant is not so bad. Being ignorant of my ignorance is a real problem.
If the FW was not a D model and if this can be confirmed then that is a step toward knowledge. Meanwhile I do not know. I only have my opinion.
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Badboy,
The sustained turn technique does not involve sustaining level flight in a turn. In fact, as I have found it to be best utilized the sustained turn technique works better if you lure the enemy into a nose low situation just before the transition into a zoom. In such a situation the trap is set when the target goes for angles with gravity against him and therefore he burns even more energy with the increase in drag.
The sustained turn technique requires the employer to maintain corner or vertical maneuvering speed which ever is the higher velocity. The setup is dependent upon maintaining this speed and it definitely requires that the target over-commits, at least from my limited experience.
This technique works even in a double inferior situation however the margin of error is reduced requiring the target to be very aggressive. A mistake in judgment of relative energy is even more costly when neither turn nor energy performance is on your side.
The sustained turn technique is a nose to tail ore two circle turn post merge set-up to lure the target into a lead turn sort of affair where the trap is set when the target is forced to make up too many angles in a too short period of time during the second merge and overshoot. The target burns all his energy going for the shot while the attacker withdrawals his energy savings into a zoom or spiraling zoom climb.
The target is left out of speed and out of luck, especially if your wingman was in the right place at the right time.
Geometry is important. The long way around gives you time to judge relative energy and will cancel any gains in angles made by the target. The more he goes for angles the better will be the set-up.
It is really important not to lose your nerve at the second merge. Hold the lag turn and then turn in at the last minute to quickly accelerate the increase in angles.
If the target stalls out then the set-up was… almost perfect. If the target just manages to hold it together, just shy of stalling, then he will be more likely to follow you up for the coup de grace.
I really like it better when a wingman delivers the goods. I can just imagine the opponent thinking “One more second and I’ve got him” just as he realizes his ultimate exposure.
These guys with the turn and burn planes often have that arrogance of superiority and they are the ones who go for the bait, I think.
I’ve been there too. Imagine my fortune to have finally realized this maneuver. It works.
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If the error can be identified then please do so, otherwise your guess must be weighted against the guess of a guy who is claiming to have actually been there and therefore his opinion is somewhat more valuable than yours in my opinion. Am I being unreasonable?
It is not a guess Josf. When Godfrey was flying a P51B there were NO FW-190D9's in service.
The plane did not exist except as a handful of prototypes that were not flown in combat nor did they ever encounter enemy aircraft.
It's like saying a Luftwaffe pilot encountered a P51D in 1942.
Godfrey was shot down and made a POW in August of 1944 flying a P51D.
http://www.acepilots.com/usaaf_eto_aces2.html#Godfrey
August 24, 1944, POW - in P-51D 44-13412, 8 miles northeast of Nordhausen, Germany, he was hit by his wingman's gunfire and bellied in
http://www.fourthfightergroup.com/resource/godfrey.html
The first 30 production FW-190D9's were delivered for SERVICE trials to III/JG54 in October '44. They did not enter service until November '44.
Crumpp
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Actually, according to data from "Green Hearts, First in Combat with the Dora 9" by Axel Urbanke, the FW 190D-9 production began in August '44 and was in 'operational sevice' with III./JG 54 in September '44.
EDITED for clarity and to add this link:
http://www.ww2.dk/oob/bestand/jagd/biiijg54.html
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Crumpp,
All that you have convinced me about is that an error has been made somewhere concerning the information being presented.
If you presume to know something based upon text written down on pieces of paper then this is something you choose to do, and even if what you think you know to be true does turn out to be true it doesn't alter the fact that you do not and cannot know everything.
You pick and choose what you want to believe and discard that which you do not what to believe. We all are guilty of this tendency. Some of us are more skeptical than others.
I choose to believe that all the information so far presented on this subject is true and false to some degree. Why? Because I am absolutely sure of one thing: that I cannot possibly prove any one of the statements so far presented with the information I currently posses.
“The plane did not exist except as a handful of prototypes that were not flown in combat nor did they ever encounter enemy aircraft.”
Even if the above were proven in some manner that has not yet been my experience to know then there remains other possible reasons for the contradiction. Other possibilities are possible; they exist even if we have not thought about them.
Example:
Godfrey actually described a situation told to him by another P-51 pilot and the account was in this manner first recorded with dates mixed up. Impossible! What does it matter?
What is certain is that the account appears in black and white as well as all those references that you have so far presented. A contradiction exists.
If you are convinced that the contradiction can be explained in a specific manner then by all means don’t let me rain on your parade.
Please allow me to be somewhat more skeptical, after all, what does it matter? I have no stake in this other than a desire to know, and so far all that I know is that the quote is very useful for understanding air combat and that a contradiction exists concerning plane type, or date, or pilot, or whatever.
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Wotan,
According to Dietmar Hermanns book:
http://www.schifferbooks.com/newschiffer/book_template.php?isbn=0764318764
It did not reach III/JG 54 until October and was undergoing factory trials in production/factory trials in September.
Interesting.
Nevertheless, Godfrey certainly did not encounter an FW-190D9 while flying a P51B.
From his service dates my guess is an FW-190A8, the most common Focke Wulf at that time.
Josef,
It has been my experience from interviewing veterans and being a veteran myself that mistakes happen. I had one pilot swear he always outturned Yaks in an FW-190A8. I believed him but pressed him for some details, as the science will tell you, this is impossible. Several days later he called me back to clarify after much thinking about it that no he did not level turn. He used yo-yo's, which is an energy tactic that looks very similar to turning.
Crumpp
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Crumpp,
Please allow me to communicate one more angle on this contention.
In the first place it seems important to express that at no time have I concluded or tried to communicate that Godfrey or any other pilot certainly and without doubt has done anything specific.
Being certain about anything derived from written text is a step I am not inclined to make without reserving a healthy bit of skepticism.
Over time it seems to me that the more information that my brain processes and the more things repeat or fit nicely together into some sort of conformity the more I am able to recognize certain things to be likely. I am able to hypothesize. I can then work on proving, if possible, but the skeptic in me demands that I recognize the difference.
What makes sense to me based upon reading Robert Shaw's book and other sources is the idea that energy tactics worked in history when the FW190 was used to combat the P-51.
Your experience with pilot interviews is a very good thing to communicate and thanks for this effort. What is important about their message? I think it is that we are all human beings and that sometimes our humanity is put to the test.
I had the pleasure to listen to Charlie Brown, Franz Stigler, and Gabby Gabreski. Listening to Gabby speak was especially inspiring. The man optimized honor in my eyes. This is not to be confused with some form of hero worship. Honorable people as simply honorable, they are not perfect, nor god like. From that experience my tendency is to afford the fighter pilots word a greater measure of credibility. Perhaps this is a mistake. I don’t think so.
Therefore I am back to my original situation to weigh the printed words of Godfrey and Shaw against the printed words of Crumpp and his resources. No one comes up short if my mind simply remains open until further evidence can remove doubt.
If during your interviews your wish is to get specific and exact information then I’m wondering if the communication takes on the form of interrogation. This is my imagination. I don’t know. If so then the incentive to be accurate may be displaced by a desire to do something else, and this would be a shame, in my opinion. That is all I have to work with since this subject is another one that leaves me without enough information to draw any absolute conclusions.
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What makes sense to me based upon reading Robert Shaw's book and other sources is the idea that energy tactics worked in history when the FW190 was used to combat the P-51.
Absolutely. What I draw from this encounter is that each fighter against it's contemprary had it's advantages. I think Godfrey ran into a expert pilot in an FW-190A8 cleared for the new boost pressures that had just been emplaced the previous month.
Or
He ran into an expert pilot equipped with the new engine the FW-190A8 was cleared for the previous month.
Impossible to answer without more information.
Honorable people as simply honorable, they are not perfect, nor god like. From that experience my tendency is to afford the fighter pilots word a greater measure of credibility. Perhaps this is a mistake. I don’t think so.
Exactly. These men are very honorable and you must understand that there is nothing dishonorable or dishonest to be found.
Good example is the FW-190A8 pilot. Study up on a yo-yo. It is nothing more than a climbing or diving TURN using the dynamics of energy and geometry to make up for turn radius. It has been the cause of much confusion in the history of the airwar. For example you will find many claims of Marsailles "outturning" P40's in the Desert. Talk to his wingman and he will tell you Marsailles conducted yo-yo's.
When he said he outturned yaks, it was the truth from his viewpoint in the cockpit.
If during your interviews your wish is to get specific and exact information then I’m wondering if the communication takes on the form of interrogation.
Your hardly in a position to make such an assumption. No they are discussions. I have found the pilots very much like to talk about their aircraft especially with someone who is knowledgable. I find them very enjoyable and I believe they do too. I don't think they would call back as often as they do if they were not.
Crumpp
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Crumpp,
If you read into my words that I have made an assumption concerning your communication then you are extending your imagination past the boundaries of good cause. I intentionally used specific wording so as to communicate the firm believe that an assumption on my part is wrong.
My use of the word ‘interview’ was in error if your communication is instead better described as ‘discussion’. In this manner I now have more information and can form a better, more accurate assessment of what you are trying to communicate. From a place of ignorance we are all bound to make mistakes. I thought I had made that quite clear already.
On the subject of assumptions it may help for us to not assume either of us are completely ingornant. One could ask the other: “if” you don’t know this then… or ‘if’ you have made an assumption then you are ‘in no position to…”
I am quite able to employ in simulation something similar to what Robert Shaw describes as the ‘High Yo-Yo’. My tendency is to not claim absolute knowledge on this or any particular maneuver. Why am I writing on this forum? I want to know more and gain insight where my doubts remain.
Confusion, I think, results from people who assume that they know something when in fact they do not and then they go about communicating this error. Is it not better to communicate with a healthy reserve of skepticism?
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If during your interviews your wish is to get specific and exact information then I’m wondering if the communication takes on the form of interrogation. This is my imagination. I don’t know. If so then the incentive to be accurate may be displaced by a desire to do something else, and this would be a shame, in my opinion. That is all I have to work with since this subject is another one that leaves me without enough information to draw any absolute conclusions.
Sounds like your wondering if I interrogate and put these guys under pressure so that I get the answer's I want!!
Would not be a very good technique for writing a history book about the events they lived through.
My use of the word ‘interview’ was in error if your communication is instead better described as ‘discussion’.
It is the use of the word "interrogate".
On the subject of assumptions it may help for us to not assume either of us are completely ingornant.
I certainly do not assume you are ignorant nor anyone else. There are some very intelligent folks who prowl these boards.
Confusion, I think, results from people who assume that they know something when in fact they do not and then they go about communicating this error. Is it not better to communicate with a healthy reserve of skepticism?
Confusion comes from many sources. One is being verbose and another is a passive agressive style.
Enjoy the discussion, Josef but would like to see the thread get back on track.
I think your a good guy and I hope you find the answers you seek.
Crumpp
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Crumpp,
Please understand that if you percieve aggression on my part that this is not an intended result.
If I do not know something then I ask questions based upon what I do know.
For example I may know that 'if' something happens then something else 'may' happen. If the idea is in my mind then I see no reason not to ask the question.
Now I see that more care is needed when asking questions if miscommunication is to be avoided.
On the other hand one can simply keep quiet.
If we do manage to communicate, in the right place, on the right subject, at the right time, with the right words, then a miracle has occured, in my view.
Meanwhile, I think it is your interest in the FW that has inspired my participation on this board.
Thanks.
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Now I see that more care is needed when asking questions if miscommunication is to be avoided.
Don't read into it, Josef. There is no miscommunication at all. Things are fine and I look forward to seeing your post's.
I think the sidetrack subject is covered is all.
Crumpp
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Sorry to return to a question covered earlier about maximising energy before a merge.
My real question is while diving may be a valid tactic is it really a thing you should do every time? What i am really saying while you may maximize your total energy should you value k.e. as high as p.e.?
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Originally posted by niknak
Sorry to return to a question covered earlier about maximising energy before a merge.
My real question is while diving may be a valid tactic is it really a thing you should do every time? What i am really saying while you may maximize your total energy should you value k.e. as high as p.e.?
Hi niknak
In theory, you could argue that either way, you have the same amount of total energy, so it shouldn’t matter if you have it as potential or kinetic energy, but it isn’t that simple. Having your energy in the form of speed gives you more options at the merge, the option to extend or zoom climb, use the vertical, or if you decide to make a high aspect guns attack, your aircraft will be more stable and you will add speed and energy to your gun or cannon rounds. If you decide to commit to a hard turning engagement, and you start out near your corner velocity, you will begin the fight with maximum rate turns, and you can decide which direction you want to turn in based on the geometry of the fight, and not just which direction gravity is pointing. If you arrive at a fight high and slow, you may still have the same total energy, but being less maneuverable, you may only be able to turn level, or nose low which limits your options, and your initial turn rate will be frustratingly low. Being slower, you will be more vulnerable to that wingman you didn’t spot, and if you need to take a low g high aspect shot, your aircraft will be less stable, because pitch oscillations are less effectively damped at low speed, so the scatter on your cannon or gun rounds will be worse. If the bandit has more energy than you thought coming in, getting out of the fight may require more drastic action, such as a defensive spiral dive.
I’m not saying it is always the best way to enter a fight, but if you go to the dueling arena and try the alternatives with similar aircraft, you will see what I mean. But even that isn’t so simple, diving into the merge for vertical turning room is a maneuver that has a lot of subtleties, particularly if your opponent knows what you are doing, and there are many variations on the theme. If you want to spend some time in the dueling arena, I’d be happy to show you some of those variations :)
Hope that helps...
Badboy
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It is useful to consider tactics from an equal situation first where both combatants are at the same altitude, the same speed, and heading toward each other so as to eliminate all the other variables of relative position and energy.
Even if the idea is a simple consideration of doctrine as to what is more important generally between the energy of speed and the energy of altitude the co-altitude merge situation again becomes important as a point from which to begin logical consideration.
I think that this becomes very clear when flying along on patrol and it is first discovered that an engagement is imminent.
The first consideration involves a judgment of relative position and energy. In order to make such a judgment time must pass for relative position to change so as to provide the information necessary to calculate the rate of change and a value for relative energy. Meanwhile what is to be done?
Climb, dive, turn, or do nothing? Go for more energy? Go for more altitude?
If the threat is determined and contact will occur or is desired then it makes sense that the required action is to turn toward and aim at the target.
If the target is lower then turning toward the target is going to result in the loss of altitude and increases in speed. Here again it is probably better to start thinking tactics from a co-altitude merge, so as to eliminate variables that otherwise determine a choice between gaining speed or gaining altitdue?
The co-altitude merge situation is relativly inevitable because the fight is on and it would not be a good idea to turn away from the fight. It is not a good idea to climb for this reason unless the target is higher. Any turns away from the head-on merge will give the enemy plane the advantages of geometry. Any turns will move the enemy plane closer into your rear hemisphere.
So the question to answer may be ‘how to’ gain an advantage after a head-on merge. But before that is done it may be useful to explore the extreme conditions that can occur even before that head-on merge occurs.
What if the merge is conducted at a very slow airspeed? What if the merge is conducted at a very high airspeed?
Climbing to arrive at a merge will result in slowing down and this brings us back to the co-altitude merge. Also it would be a purely defensive consideration to fight a higher plane. The enemy flying higher is known to posses more energy unless your airspeed is accumulated in a resent dive or that your cruise speed is very high. The higher the enemy fighter the more speed you would need to even consider a chance at conducting offensive maneuvers. This thinking again brings us back to the co-alt merge.
If the attack is conducted during a dive toward the target then the merge may occur at a very high speed. Here it again changes the nature of the initial decision to attack. If the enemy is seen lower initially then the condition of superiority is obvious in proportion to the altitude difference. If a condition of superiority exists initially then the question of energy management is much less important that considerations of relative position. In other words from an extreme altitude advantage there is an ability to maneuver into better position. From any advantage there is the ability to maneuver purely on an offensive basis. What this thinking points out is that the merge is something that occurs when combatants are vying for position from equal position because neither holds an initial advantage and the speeds during the merge are generally not going to be much above or below cruise speed.
Imagine a situation where two pilots see each other in the distance at the same time. Both pilots do the nature thing and they turn to fight, to do otherwise would be defensive. Neither pilot has a great advantage to exploit because if they did then the other pilot would be inclined to turn and run. This makes perfect sense. I don’t think we are talking about surprise attacks, bounces, and other such defensive situations. When the fight starts the assumption is that both planes have offensive maneuvering capabilities and the greater the situation begins from an unequal situation the less is the need to consider anything other than desperation.
Back to the two pilots at distance turning into each other and this time one of them goes high for altitude and the other one goes low for speed. The net result is the both pilots will remain relativley equal in energy and both will have a better idea of relative energy states because time will change things and if both pilots are energy conscious then they will note the rate of change. So what has occurred? For one thing; the inevitable merge has been delayed.
This brings us back to that ‘how to’ gain an advantage after a head-on merge, because the merge is going to occur. Well, you may say what if the guy who went for speed just keeps on diving, or what if the guy who went for altitude just keeps on climbing? I think that this is called extending away from the fight, it is defensive, it is turning away from the head-on merge, it is giving up angles and geometry.
What about the situation where they both go for altitude or both go for speed? Think about that for a moment because this consideration is very instructive. How does one judge relative energy? Closure rates and the rate of change in relative position during the merge help. If both pilots climb toward each other then closure rates are almost maximized (maximized when heading directly toward each other) but it is difficult to note the rate of change in angles. Each pilot can see little or no change in angles. The same is true in a situation where both pilots dive for speed. Why is this important? If you go back to the situation where one plane is climbing while the other plane is diving it should become obvious as to why it is important to realize that the rate of change in angles is important for judging relative energy states. The climbing plane will lose relative angular gains relative to the faster plane in a dive because the faster plane is traveling farther. The climbing plane will note that the faster plane is moving into his rear hemisphere while the faster plane is able to maintain the slower plane in his front hemisphere relatively better.
In other words the rate of change of angular gains favors the faster plane diving over the slower plane climbing. To visualize this simply imagine a dot near your gun sight that is moving (rate of change) from the gun sight towards your rear view.
This is where the sustained turn technique really shows its purpose. The sustained turn technique is a method of setting up a way to judge relative enegy states with minimum risk.
When then the idea is to maintain the balance between offense and defense then vertical maneuvering speed is the ideal. Any variation from vertical maneuvering speed is stressing offense or defense. Going faster than vertical maneuvering speed tends to be defensive while going slower tends to be purely offensive.
Examples of cases where faster is offensive and slower is defensive tend to fall into the area of desperation.
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Originally posted by JG14_Josf
This is where the sustained turn technique really shows its purpose. The sustained turn technique is a method of setting up a way to judge relative enegy states with minimum risk.
how do you come to this conclusion? unless you know 1st hand before using the sustained turn technique what each plane type is capable of..if one does not know the abilitys of one's enemy then I find this to be a bigger risk then minimum
my reason for thinking such way is that your description of using the sustained turn technique is to maintain corner speed/velocity but this is much higher than the speed required for flying the best sustained turning speed, where are you using sustained turn if you are at corner speed?
( if you are getting this from Shaw's book, point me to the pages so I can re-read it please)
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Fighter Combat by Robert Shaw
One-Versus-One Maneuvering, Dissimilar Aircraft
Low versus High Wing Loading with Similar T/W
page 179
Starting with:
"Because fo the T/W equivalence..."
The fight is on and unavoidable therefore a head on merge is the inevitable best possible initial contact. Any other form of contact is defensive for one of the combatants.
The sustained turn technique has the added advantage of illustrating the vital importance of employing correct post merge geometry. In this case the nose to tail turn allows for a safer evaluation of relative performance.
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Originally posted by JG14_Josf
The fight is on and unavoidable therefore a head on merge is the inevitable best possible initial contact. Any other form of contact is defensive for one of the combatants.
Joe, I don’t think that is a direct quote from Shaw, if it is, it must be out of context, because it simply isn’t true. A lead turn is almost always preferable to a head on merge, and is certainly not defensive.
Originally posted by JG14_Josf
Fighter Combat by Robert Shaw
page 179
Starting with:
"Because fo the T/W equivalence..."
Joe, I just checked the passage you are referring to, and I believe the warning I posted earlier is valid. In the following paragraph to the one you referred to Shaw gives an example of the sustained-turn technique, where he describes both fighters flying at optimum speed for the sustained turn, but then he says that grabbing greater angles would require the fighter to pay dearly in terms of energy… But here is the catch! That is a statement that only applies to Jets not Prop’s. The reason is that when a jet fighter is at its optimum speed for a best sustained turn, it can actually pull more g and increase the turn rate, because it is well above stall speed and has more g available, and as he points out, it costs energy as you can see from the jet EM diagram I posted. In a prop fighter, if you are at the optimum speed for the best sustained turn, you can’t grab any more, because you have no more g available because you are already on the edge of the envelope and the stall. Remember, Prop’s stall fight, Jet’s don’t! The description doesn’t survive the translation from Jet to Propeller driven fighters.
Do you know where else in the book Shaw refers to the “sustained-turn technique”?
Badboy
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Badboy,
If there are no quotation marks then isn’t it a good idea to ask first before assuming the words are quoted?
Your interpretation of the sustained turn technique is different from mine.
I don't see much use in trying to communicate with people who are so prone to misinterpretation, who then assume authoritah (Eric Kartman).
If anyone else has any questions on this subject I am more than willing to try to communicate what I think I know (I like to write). What is communciated by Shaw is quite useful knowledge in my experience as it applies to simulated WWII air combat. I am almost reluctant to arm my potential rivals.
Shaw:
"The energy fighter pilot shoud set up a nose to tail turn at maximum sustained-turn-rate speed (or vertical-maneuvering speed, if that is higher), either level or slightly nose-high."
If you are being told that "Figher Combat" is for jets and that it does not apply to props, then you may want to do your own reading and make up your own mind.
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Originally posted by JG14_Josf
If there are no quotation marks then isn’t it a good idea to ask first before assuming the words are quoted? Your interpretation of the sustained turn technique is different from mine.
It doesn’t matter who wrote it, it is still wrong.
Originally posted by JG14_Josf
If you are being told that "Figher Combat" is for jets and that it does not apply to props, then you may want to do your own reading and make up your own mind.
Now you are the one misinterpreting, I never said anything about “Fighter Combat” not applying to prop’s, it does. However, Shaw goes to great lengths to describe energy and angles tactics, and that has always been just as applicable regardless of the aircraft type. The fact is, that not everything in Shaw’s book is applied in the exactly the same way, regardless of aircraft type, and that distinction is important.
Originally posted by JG14_Josf
Your interpretation of the sustained turn technique is different from mine.
I don’t know what your interpretation of the sustained turn technique is, perhaps you can explain, because so far what you have said doesn’t make sense, and some of it is just plain wrong.
Sustained turns can be conducted at any point in the envelope where the aircraft has zero specific excess power, and those points are shown in the following diagram for a prop’ and a jet. When Shaw refers to the optimum speed for the best sustained turn, he is referring to the points shown in my diagram and his comments need to be taken in that context.
(http://www.badz.pwp.blueyonder.co.uk/images/PropvJet3.jpg)
You can see that if you are flying the jet, Shaw’s comments at the top of page 180 regarding grabbing greater angles makes perfect sense, because to do so would mean reducing your sustained turn rate, you would effectively be falling into an energy bucket. However, you can also see from my diagram, that those comments don’t apply in the case of the prop’ fighter, if he is at the optimum speed for sustained turning, the situation is entirely different. I’m only trying to clarify this for you, and I’m always willing to answer questions.
Badboy
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Originally posted by Badboy
Sustained turns can be conducted at any point in the envelope where the aircraft has zero specific excess power, and those points are shown in the following diagram for a prop’ and a jet. When Shaw refers to the optimum speed for the best sustained turn, he is referring to the points shown in my diagram and his comments need to be taken in that context.
(http://www.badz.pwp.blueyonder.co.uk/images/PropvJet3.jpg)
You can see that if you are flying the jet, Shaw’s comments at the top of page 180 regarding grabbing greater angles makes perfect sense, because to do so would mean reducing your sustained turn rate, you would effectively be falling into an energy bucket. However, you can also see from my diagram, that those comments don’t apply in the case of the prop’ fighter, if he is at the optimum speed for sustained turning, the situation is entirely different. I’m only trying to clarify this for you
thank you Badboy, that is what I was trying to get at, across or shoot for in my posting............. Shaw's book tactics/studies can be "applyed" to both Jet's and Props, but it does not "apply" to both if you take it out of context, your diagram helps one keep it in context easier I think, again thanks
very good material here
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"and some of it is just plain wrong."
Badboy,
If you do not understand what I write then how can you know if it is wrong?
I can see that the idea here is not to discuss things; instead the idea is to twist words around to come up with a means to discredit each other and win the word fight.
I see no reason to play this game, however, if you can please explain in your best language what exactly is 'just plain wrong' with what I wrote then perhaps I can defend my integrity.
Otherwise this one-upmanship crap is just a big waste of time.
The sustained turn technique works in simulated WWII combat, it works good and when it is understood the concept of aerial combat becomes a little easier to conceptualize, in this measure the book ‘Fighter Combat’ is specifically applicable to air combat with prop planes (in simulation).
If anyone is telling you otherwise then, again, it may be a good idea to read for yourself and make up your own mind.
Note the word ‘if’ and realize that ‘if not’ then the subsequent message does not apply.
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Originally posted by JG14_Josf
If you do not understand what I write then how can you know if it is wrong?
Because you said…
Originally posted by JG14_Josf
The fight is on and unavoidable therefore a head on merge is the inevitable best possible initial contact. Any other form of contact is defensive for one of the combatants.
That is “plain wrong” on two counts, firstly the head on merge is never the best possible initial contact. Even if it looks as though a head on merge is likely, it is always better to try and create some flight path separation for a lead turn, doing so isn’t defensive, it is an aggressive approach to gaining angles.
Originally posted by JG14_Josf
I can see that the idea here is not to discuss things; instead the idea is to twist words around to come up with a means to discredit each other and win the word fight.
My idea is to try and be as helpful as possible, but it is difficult to point things out when folk get so defensive. Unfortunately, some folk aren’t just wrong, they are wrong with conviction and persistence, and no amount of reason helps.
Originally posted by JG14_Josf
I see no reason to play this game, however, if you can please explain in your best language what exactly is 'just plain wrong' with what I wrote then perhaps I can defend my integrity.
Certainly, here are a few examples:
Originally posted by JG14_Josf
Any turns away from the head-on merge will give the enemy plane the advantages of geometry.
Nope, if you can create enough separation for a lead turn prior to the merge, there is great potential for advantage, so that statement is incorrect.
Originally posted by JG14_Josf
Any turns will move the enemy plane closer into your rear hemisphere.
Nope, a lead turn will gain angles, and help solve your aspect and angle off problems.
Originally posted by JG14_Josf
The sustained turn technique is a method of setting up a way to judge relative enegy states with minimum risk. The sustained turn technique requires the employer to maintain corner or vertical maneuvering speed which ever is the higher velocity.
Actually, the sustained turn technique is a way to perform an optimal sustained turn, with minimal energy loss, and that only occurs near corner velocity in a jet, not in a prop. You appear to be quoting Shaw out of context and confusing the idea with energy tactics in general. There are other examples, but this should make the point.
Originally posted by JG14_Josf
Otherwise this one-upmanship crap is just a big waste of time.
If there is any one-upmanship here it isn’t coming from me, I only post to try and be helpful. It would certainly be a lot easier to ignore folk when they propagate errors or misconceptions, but it isn’t very helpful for those who might be misled by it. But as I said, it is very unfortunate that some folk aren’t just wrong, they are wrong with conviction and persistence. When that happens I guess it is just easier for them to make accusations about one-upmanship, and resort to polemics instead of the subject, which is always a shame.
Hope that helps...
Badboy
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Badboy,
A reasonable person will stand by his convictions and honor his word.
If you are up to it then let us continue. If you are not then don't waste my time.
You continue to misunderstand what I write, you make conclusions concerning your error and the end result is that you destroy my reputation unless I defend myself.
Damage has already begun. I have no wish to further cause injury; however, if the goal is to be reasonable then we can proceed.
First:
Is your thinly veiled innuendo an indirect attempt to insult me?
If so please just dispense with the misdirection and state your opinion.
If not then why post such garbage?
Don’t waste my time.
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Joe,
I'm just trying to be helpful here, so if you ask me to point out errors so that you can defend the points, try not to act so wounded when I do. If I take the trouble to point out those errors, and you believe I’m wrong, it would be more constructive to respond with reason instead of silly accusations. Meanwhile I’ve made a significant number of technical and factual statements and I’m still waiting for a reasonable response, but I’m only prepared to discuss the air combat and aircraft performance issues.
Badboy
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Since Mr. Badboy is unwilling to proceed in a reasonable manner it serves me to defend his double talking personal attacks, and then this board is off my favorites list.
Take care everyone else and to Mr. Badboy I hope you can someday own up to your self.
Badboy accuses me of:
"silly accusations"
He insinuates:
"they propagate errors or misconceptions"
I had asked if he would clarify if he meant to direct that statement to me personally and he proceeded to do what he then said he would not do:
"I'm only prepared to discuss the air combat and aircraft performance issues"
If that was true then why all the crap like this:
"resort to polemics instead of the subject"
Note too that the first deviation from air combat and aircraft performance issues was this:
"Joe, I don’t think that is a direct quote from Shaw, if it is, it must be out of context, because it simply isn’t true. A lead turn is almost always preferable to a head on merge, and is certainly not defensive. "
Why make an assumption concerning a sentence that is not in quotes without asking first if it was meant as a quote?
Why bring up the whole subject of Jets too?
If something is not understood then why not simply ask questions to find the answers rather than jumping to conclusions?
Shaw clearly states that during the sustained turn technique it is vertical maneuvering speed that is the priority not sustained turn speed.
The whole comparison of Jet aircraft performance is irrelevant. The object of the maneuver is to lure the enemy into burning more energy and although it is not specifically stated; the maneuver works as a very good and safe method of judging relative energy after a merge.
As to the ridiculous Straw Man argument concerning lead turns; that too is superfluous to the discussion at hand i.e. the sustained turn technique. Why bring it up?
Even that Straw Man is a weak one.
Lead turns are not the subject of this discussion however if they were then it stands to reason that the only way to gain separation for the lead turn is if the opponent allows it and if he does not then the merge is back and the first one to try the lead turn has in fact given up angles that must be taken back at the cost of energy.
The sustained turn technique actually works out to be a lead turn type of end game. But why talk about this stuff when so much crap can be thrown around?
I will not waste my time here any longer.
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Hi Josef,
Badboy was helpful and rational.
Your reflective communication style, most probably involuntarily, leads to confrontation style posts.
Try not to post so much "Why did you do this to me?" questions, but more "Do you mean X?" ones if you suspect a misunderstanding, "X" being a fair approximation of what you can figure out the other guy is trying to tell you.
(That's really just a meta-level comment, independend of the context. Not really a question of style, but rather one of what works of what doesn't.)
I hope you change your mind and stay on this board :-)
Regards,
Henning (HoHun)
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Hi Badboy thanks for the duelling offer, unfortunately my PC is playing up at the moment and i am off to Japan for a year shortly so will probably not be able to get it up and running in time.
However the reason fo my slight sceptisism (sp?) is the plane's ability to turn its kinetic energy into potential energy. (with what efficiency will a WW2 plane turn speed into alt????)
The scenario i envisage against an opponent who grabs alt while you dive is you gain angle intially and bag him quickly or he gains a desicive alt advantage and can dictate the engagement.
I do think it is an interesting area and if i do get my PC up and running soon i would love to run through a few scenarios in the duelling arena if you were still up for it.
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Originally posted by niknak
I do think it is an interesting area and if i do get my PC up and running soon i would love to run through a few scenarios in the duelling arena if you were still up for it.
Sure, anytime, always happy to help. Good luck getting your PC sorted.
Badboy
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Badboy:
It sounds as if the exercise equally weights altitude, climb rate, speed, and acceleration. This follows from the assumption that the Pilot's goal is to maximize the increase in total energy?
-Blogs
Originally posted by Badboy
Hi HoHun
Firstly, let me apologize for the following verbosity… I know I could explain this to guys like yourself and HiTech much more briefly than I’m going to, but I’m going to take the opportunity to get back to basics in the hope I can also open the subject to some of our less technically minded friends. Here goes…
...
Hope that helps…
Badboy
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Originally posted by joeblogs
Badboy:
It sounds as if the exercise equally weights altitude, climb rate, speed, and acceleration. This follows from the assumption that the Pilot's goal is to maximize the increase in total energy?
-Blogs
Yep, I think you have got it.
When you produce the schedule in the example I posted previously you are optimizing the Es and the Ps at the same time, here are the two expressions:
Es = V^2/2g + h
Where V is the speed, g is gravity and h is the altitude, and is measured in units of length (feet say). And:
Ps = V/g dV/dt + dh/dt
The Es terms contains the kinetic energy, or speed, and the altitude, or potential energy, and the Ps term contains the acceleration and climb rate. But it doesn't weight them equally because in the expression for Es the speed is squared, which means for aircraft capable of higher speeds it becomes more important, which is why folk can get the false impression that it only matters for the jets. But you can see from this diagram:
(http://www.badz.pwp.blueyonder.co.uk/images/energytransfer3.jpg)
That the proper schedule may be an initial dive, followed by a climb in which you gain speed, followed by a diving entry into the fight, leading to this sort of merge:
(http://www.badz.pwp.blueyonder.co.uk/images/Hook2.jpg)
is not only the most energy efficient way into a fight, but is also very sound in terms of the BFM, regardless of whether the bandit takes away your turning room or not.
Remember, there are only three basic building blocks to BFM, and the strategy I've explained optimizes them all.
Hope that helps…
Badboy
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Hi Badboy,
>(http://www.badz.pwp.blueyonder.co.uk/images/energytransfer3.jpg)
My disagreement with that diagram is only the position of the dotted line on which the B-C segment runs. This is the speed of best climb, and for WW2 propeller fighters, it's usually farther to the left. If it would run through point A, then the diagram would look good to me :-)
The reason this makes a difference is that the lines of equal energy have less curvature there so that relatively little altitude can be converted into the speed needed to reach the dotted line.
Accelerating from 100 mph to 160 mph IAS by putting the nose down a little while going at full throttle probably wouldn't be perceived as a dive because it's over rather quickly :-)
But anyway, the important point that remains is - how do you determine the optimum point D? :-)
Regards,
Henning (HoHun)
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What a fantastic thread. Thanks to all contributors for expanding my mind. Just to see if I'm actually learning anything I will attempt to answer HoHuns last question "But anyway, the important point that remains is - how do you determine the optimum point D? :-) ".
Point D would be the minimum amount of energy deemed acceptable, or at least the maximum atainable, before the fight is initiated, I think.
As an example; either through intuition or real information, visual, reported or otherwise you must decide where you expect the fight to be initiated. i.e. I could guess at, or hear a report of, or see an enemy at 10K moving at 300mph. I want to have the maximum of energy, and thus options, available to me when I meet him. This means I want be at least at 10K going at least 300mph when I get there to arrive at a co-e situation. Using Badboy's information I could compute a climb profile that would get me to my desired E state (10K@300MPH) in the minimum amount of time.
Seems like someone could make a java applet or something where you could input your plane type along with points A and D, and it would give you points B and C, which would give the quickest possible intercept climb profile and a total estimated climb time from point A to D. This would allow you to plan your flight path so that you do not initiate the fight before, nor waste time after, you have achieved your desired E state.
Likewise if you were jumped you could input point A and time available before the fight is initiated and it would give you points B, C and D which would allow you to maximize your E before the fight and/or make the decision to dis-engage if you felt the E states were to disparate for your plane and/or skills to overcome.
I hope that I am conveying and interpreting this information correctly.
This brings rise to several further questions.
How does one define when the fight is initiated anyways? Awareness of the others position and the decision to attack them? Is there a generally accepted definition? Are there defined "stages" of a fight?
I like to think of WWII air combat as 3D real-time chess. I use the term "fight initiated" as the point where the chess pieces have been placed on the board, one pilot or the other may already be missing a pawn or worse do to errors in the initial setup, but "fight initiated" is when the setup is over and the game begins in earnest.
Pardon my blatherings. Thanks for the insight Badboy, Shaw, HiTech and everyone.
g00b
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Hi HoHun,
That diagram is only intended to illustrate the principles involved, I left the numbers off deliberately so that discussions about any particularly values wouldn’t cloud the principles involved. Having said that, even though I haven’t indicated any particular speed, I agree that taken in proportion with the rest of the diagram it does appear a tad too fast, so I have edited the diagram.
Originally posted by HoHun
Hi Badboy,
My disagreement with that diagram is only the position of the dotted line on which the B-C segment runs. This is the speed of best climb, and for WW2 propeller fighters, it's usually farther to the left. If it would run through point A, then the diagram would look good to me :-)
However, I also think that point A would be below the correct speed for most WWII fighters. If we put some numbers to it, (which I hope won’t lead to any hair splitting) just for the purpose of discussion, we can assume that the speed axis of the diagram has major tick marks at 100mph intervals, and that the altitude axis has major tick marks at 10,000ft intervals. If that is the case, we can see the diagram represents a fighter with a top speed at sea level of 350mph, and a top speed of 450mph at its critical altitude of about 24,000ft.
Now, if that is the case, then the scenario we are looking at here is this… Imagine our pilot has just been in a hard turning engagement, he has been riding the edge of the envelope and the enemy aircraft tries to pull his nose high, he pulls up to follow him gets enough lead for a shot and hanging on the prop gets the kill. The bandit explodes, showering his canopy with hair teeth and eyeballs! He then becomes aware of another threat. At that point our pilot is at point A, 20k and 150mph, and then dives to the speed for best energy transfer, at around 190mph and 18k. He then climbs, increasing his speed to about 230mph at point C at just over 30k, and then dives back to a speed of 320mph at a slightly lower altitude, which places him close to his corner velocity at that altitude, and ready to maneuver.
Of course, if he was already cruising at a speed of say 250mph at point A, he would need to zoom climb, and if he was already close to the 190mph speed for best energy transfer, he could simply execute his climb without either the diving or zooming part.
Originally posted by HoHun
The reason this makes a difference is that the lines of equal energy have less curvature there so that relatively little altitude can be converted into the speed needed to reach the dotted line.
The type of dive involved here isn’t just any old dive, in order to dive and gain speed most quickly with the least cost in energy it should be a zero g dive that minimises the induced drag. Following an Es curve down, should always get you the best speed gain for the least loss in altitude, regardless of where it is on the diagram.
Originally posted by HoHun
Accelerating from 100 mph to 160 mph IAS by putting the nose down a little while going at full throttle probably wouldn't be perceived as a dive because it's over rather quickly :-)
I agree, but those speeds are below the sort of speeds I had in mind, and I think that 160mph is too low for the best energy transfer speed, particularly for the heavier late war fighters, which is why I have been trying to stick to general principles and avoid discussing numbers. I think there have been a lot of threads on that topic already, and being specific will always cloud the issues because it doesn’t matter what numbers are used, there are always exceptions.
Originally posted by HoHun
But anyway, the important point that remains is - how do you determine the optimum point D? :-)
Interestingly enough, the practical execution of the technique has a lot in common with the methods used to calculate it, because those methods are numeric and iterative. Carrying out those calculations for educational purposes is instructive, but unfortunately carrying out the calculations for specific cases in combat is only of any real value if you have the advantage of modern GCI or AWACS that can stream the data to onboard computers, where you can apply it in real time… Otherwise a certain amount of judgement is required, which is how fighter pilots have been applying the technique since Korea. In terms of a more practical approach, the speeds for best energy transfer are given in the dash one of most third generation fighters and used to determine the climb schedules. When notified by ground controlled intercept of an approaching enemy, a modern fighter pilot, if below the best energy transfer speed, would unload to zero g until they reach that speed, then climb to an altitude above the enemy if possible. I’ve already described an optimal approach for an imminent engagement, but if the bandit tried to run away, the pilot would continue to climb to 36k for the chase, and in a prop fighter you might go to the critical altitude for the chase for maximum speed. There is an article on SimHQ where I describe the Co-E chase. Everything else remains as described, but one last point, how do you do it in Aces High?
Well, these technique can also be used in that way to good advantage in AH. In order to explain what I mean in terms of the practical application, let’s consider how you would apply these principles in the duelling arena with both pilots starting on the runway. Firstly, both pilots might take off on auto climb, but climbing right off the runway is the wrong thing to do, because it takes too long for the aircraft to accelerate to the best climb speed while climbing. Ideally, you would like to unload and get to that speed as soon as possible, just as I’ve shown in the diagram, but because you are already on the deck you just lift off and accelerate in level flight until you reach a speed just above the best climb speed, then you begin to climb.
Now, you climb as rapidly as possible as your radar dots approach each other. At some point you know you need to convert some of your altitude back to airspeed for the impending merge, and you have asked what is the point D in terms of airspeed and altitude, but more importantly, the way I apply it, is how do you determine point C, the point when you commit to the push over. Once you begin the push over at point C, point D will be determined by your initial timing and experience. Begin the push over too late, and you may not have enough speed at the merge, begin it very late, and you may lose sight of the bandit. Begin the merge too early, and you will gain too much speed, and lose energy and maneuverability. Also, when you time your push over will depend on the type of engagement you intend to fly, if you intend to follow the merge with a zoom climb for an energy fight, or whether you intend to pitch back vertically, or slice it, for an angles fight. And there are a lot of variations. In a duel, guys even try to disguise their energy by diving steeply and throttling back during their descent. However, the real secret is being very familiar with your aircraft handling qualities, so that your timing and judgement are correct, or at least close enough. That’s why some guys spend many hours practicing these techniques in duels until they have honed their skills and can judge the correct timing against any type of enemy aircraft and engagement style. If you don’t think this works, take any experienced AH pilot to the duelling arena, and see what they do, if they are good, the only thing that will change, will be how well they do it :)
Hope that helps…
Badboy
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Hi g00b,
It sounds to me like you have a pretty good handle on this stuff. I’ll just help you with some points that I didn’t cover in my reply to HoHun
Originally posted by g00b
How does one define when the fight is initiated anyways? Awareness of the others position and the decision to attack them? Is there a generally accepted definition? Are there defined "stages" of a fight?
Yep, there are normally four stages, Detection, Closure, Engagement and Egress, but they are often expanded to include additional terms. So for example, the detection phase for us would simply be detection on radar beyond visual range, or visual sighting. Once detected, a term often used is to Sort the contacts, to determine their formation, or current activity. The next term would be Target, which describes how you choose the target you wish to engage. The next term is Intercept, describing how you maneuver into a position to attack, the Engage phase is about bringing your guns to bear on the target, and the Egress phase is about departing the engagement in the safest most expeditious way possible… So the list might look like this:
1) Detection
2) Sort
3) Target
4) Intercept
5) Closure
6) Engage
7) Egress
Originally posted by g00b
I like to think of WWII air combat as 3D real-time chess. I use the term "fight initiated" as the point where the chess pieces have been placed on the board, one pilot or the other may already be missing a pawn or worse do to errors in the initial setup, but "fight initiated" is when the setup is over and the game begins in earnest.
Once engaged the BFM consists of four basic functions
1) Observe the bandit.
2) Predict a future position for the bandit based on your observation.
3) Maneuver in response to your prediction
4) React to changes in the situation as you execute your maneuvers.
In order to win an engagement you need to execute each of those stages as correctly and quickly as possible.
Personally, I don’t like to think of air combat like chess, because it implies that there are good moves, that have good responses, just like a game of chess, but that is more like the way Russian fighter pilots were trained to fight in the 80s and there was a well known joke that went like this… If you asked ten Russian fighter pilots what to do to solve a certain BFM problem, you would get one answer, the same one from each of them. If you asked ten American fighter pilots the same question, you would probably get fourteen different answers :)
The point is, that BFM is not really about executing set piece maneuvers, one following another, like a game of chess, it should be a more fluid and dynamic situation in which the fighter pilots will build each maneuver from first principles as they observe, predict, and react to the changes as they evolve.
Hope that helps…
Badboy
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Hi Badboy,
>Having said that, even though I haven’t indicated any particular speed, I agree that taken in proportion with the rest of the diagram it does appear a tad too fast, so I have edited the diagram.
Looks much more familiar now :-)
(With regard to the lines of equal energy, now that you've assigned actual numbers they appear too steeply inclined. The line terminating at 420 mph/0 ft should begin at ca. 0 mph/6000 ft, not at ca. 20000 ft.)
>At that point our pilot is at point A, 20k and 150mph, and then dives to the speed for best energy transfer, at around 190mph and 18k.
This illustrates why I initially said "Forget about the dive" :-) As the equal energy lines actually are quite flat, 20000 ft and 150 mph leads to 19546 ft and 190 mph, or a mere 464 ft drop. As transitions aren't instantaneous in real life (and the recovery costs energy as well), in practice you'd probably just release the stick a bit for a moment.
>The type of dive involved here isn’t just any old dive, in order to dive and gain speed most quickly with the least cost in energy it should be a zero g dive that minimises the induced drag. Following an Es curve down, should always get you the best speed gain for the least loss in altitude, regardless of where it is on the diagram.
Hm, I believe that's not strictly true. The 0 G dive, while relatively energy efficient, in most cases doesn't coincede with moving on a line of equal energy. For the latter, you need to dive vertically with the engine yielding exactly as much power as required to overcome drag. (Add power beyond that, and you'll leave the line :-)
>[...] Also, when you time your push over will depend on the type of engagement you intend to fly, if you intend to follow the merge with a zoom climb for an energy fight, or whether you intend to pitch back vertically, or slice it, for an angles fight. And there are a lot of variations. [...]
I think we're in agreement here :-) I'd even say picking the correct point D is an art and not a science - and you know how much I love science ;-)
Regards,
Henning (HoHun)
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Originally posted by JG14_Josf
The Author of the Bible?
Is it possible that you are inclined to converse on the finer points of Air Combat? Will you entertain a few questions?
Joe
Joe,
Thanks for your kind words. Sorry it's taken me so long to answer. Don't check this board regularly.
I'd be happy to answer any questions I can.
Mouse
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Originally posted by Badboy
You can see that if you are flying the jet, Shaw’s comments at the top of page 180 regarding grabbing greater angles makes perfect sense, because to do so would mean reducing your sustained turn rate, you would effectively be falling into an energy bucket. However, you can also see from my diagram, that those comments don’t apply in the case of the prop’ fighter, if he is at the optimum speed for sustained turning, the situation is entirely different. I’m only trying to clarify this for you, and I’m always willing to answer questions.
Badboy
Badboy,
Just to clarify the "props vs jets" discussion, my description was meant to apply to both, but I'm sure it's not always perfectly clear. In the case of the prop conducting a turn at "best sustained turn speed," and trying to gain additional angles, this would be done by using a low yo-yo rather than just pulling harder. In other words, the attacker is gaining angles at the expense of altitude, bleeding potential energy rather than kinetic. The results are the same.
Hope that helps.
Mouse
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Originally posted by Shaw
Badboy,
Just to clarify the "props vs jets" discussion, my description was meant to apply to both, but I'm sure it's not always perfectly clear. In the case of the prop conducting a turn at "best sustained turn speed," and trying to gain additional angles, this would be done by using a low yo-yo rather than just pulling harder. In other words, the attacker is gaining angles at the expense of altitude, bleeding potential energy rather than kinetic. The results are the same.
Hope that helps.
Mouse
Apologies may be due if this discussion is about to cross the line into the “nit-picking” region of the envelope, because while I agree with your last post, I would just like to clarify a technical point in case it is helpful to someone. While the quoted description is correct for a jet, it isn’t strictly technically accurate for a prop, because in the case of aircraft turning at “best sustained turn speed” it is only the jet fighter that can hold that speed while transitioning to a nose-low turn, it can do so by increasing its load factor. The prop driver’s speed will increase, since he doesn’t have the g available to avoid accelerating because he is already at the lift limit, so the prop can’t conduct a nose-low turn or a low yo-yo at its “best sustained turn speed.”
I think this is a noteworthy technical point because there is a distinction between angles gained due to an increase in the aircraft’s turn rate as a result of increased load factor, turning nose-low, and the geometry of the low yo-yo.
If I just consider a situation similar to one you describe in your book where “the energy fighter pilot makes the transition to a nose-low turn, maintaining speed, to slow the opponent’s angular gains,” If we assume a steady nose-low turn, and ignore the yo-yo for a moment, that description has different implications for a jet than it does for a prop, because in the case of aircraft turning at “best sustained turn speed” it is only the jet fighter that can increase its load factor to maintain that speed while turning nose-low. In order to maintain that speed in a nose-low turn it increases the load factor into a region of negative Ps, turning nose-low compensates and sustains that load and speed, with an increase in turn rate. I’ve shown that situation in the diagram below, you can see that the jet pilot can go from Aj to Bj, increasing turn rate and maintaining speed, by losing altitude at a rate equal to the amount of negative Ps.
(http://www.badz.pwp.blueyonder.co.uk/images/PropvJet4.jpg)
However, in the case of a prop fighter at “best sustained turn speed” it can’t increase the load factor or turn rate without increasing speed, because the best sustained turn for a prop occurs at the edge of the envelope where no more lift is available. Similarly, if the aircraft transitions to a nose-low turn, it doesn’t have the g available to prevent the speed increasing, so it will accelerate. I’ve shown that situation in the diagram above, where you can see that in going from Ap to Bp the prop fighter will increase speed and increase its turn rate. So, the prop fighter can increase its load factor, and its turn rate while turning nose-low, and it may gain an additional advantage for any periods of time during the yo-yo when the lift vector might be below the horizon, increasing the load factor, and thus the turn rate, but it can’t do it while maintaining “best sustained turn speed”.
In comparison then, the angular or positional advantage to the prop fighter that results from the geometry of the low yo-yo, the increase in speed during the nose-low turn, and the lift vector orientation, are all similar for the jet which has the additional potential to increase the turn rate due to turning nose-low at “best sustained turn speed” because it has the g available from the get go. Other than the subtle practical differences in control commands required during execution, and the significant differences between the way sustained turns are flown in prop and jet aircraft, the results, as you point out, are the same.
Hope that is helpful to someone.
Badboy
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Fantastic stuff Badboy and a hello to you and TC from another ex AW trainer. I just started flying again last week.
I have Two questions for the mods...
(1) Is there anyway this whole thread (save some personal bickering) can be put on a web somewhere for posterity. The info here is GOLD!!!
(2) Why is this thread in the aircraft and vehicles section, copy/move it to the training section. ... and sticky it.
dowYoda.
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Originally posted by dowyoda
Is there anyway this whole thread (save some personal bickering) can be put on a web somewhere for posterity. The info here is GOLD!!!
Try this:
A .pdf file of this thread, open it, or right click and save. (http://www.badz.pwp.blueyonder.co.uk/Files/VyThread.pdf)
Badboy
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Thanks Badz. ...
You da man.
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Originally posted by Badboy
Apologies may be due if this discussion is about to cross the line into the “nit-picking” region of the envelope, because while I agree with your last post, I would just like to clarify a technical point in case it is helpful to someone. While the quoted description is correct for a jet, it isn’t strictly technically accurate for a prop, because in the case of aircraft turning at “best sustained turn speed” it is only the jet fighter that can hold that speed while transitioning to a nose-low turn, it can do so by increasing its load factor. The prop driver’s speed will increase, since he doesn’t have the g available to avoid accelerating because he is already at the lift limit, so the prop can’t conduct a nose-low turn or a low yo-yo at its “best sustained turn speed.”
Badboy
Badboy,
Once again, sorry for the long reply time. As I've said before, I just don't get many opportunities to check this discussion.
There are several exceptions I would take to your comments above:
1) A prop aircraft most certainly CAN perform a nose-low turn (low yo-yo) at full power and best sustained turn speed without increasing speed. I've personally done it in both props and jets, and I'm no magician. The reason is that...
2) the prop fighter is NOT at the stall boundary while performing a max sustained turn. Granted it's much closer than the jet is to that boundary, but the prop can still increase AOA and drag above that required for best sustained turn speed. Your diagram is misleading on this point. Best sustained turn speed for either props or jets is roughly the same as best climb rate speed (Vy). I think you'll agree that Vy is normally well above stall speed (or stall AOA) for props. For most fighters (props or jets), best sustained turn rate is achieved at about the point that the aircraft starts to buffet. Pulling harder typically doesn't increase G much, but it will increase AOA (up to the point of stall) and drag. The added drag offsets the descent rate in the low yo-yo to maintain speed. Keep in mind here that we're not talking about a split-S. I'll grant that most prop fighters will gain speed in a full-power split-S even at max-AOA. A low yo-yo in this case may be only a degree or 2 below the plane of the bogie's turn...although most prop fighters can descend much faster than this and still maintain speed.
3) Of course, it's not really necessary to maintain max sustained turn speed for a low yo-yo to work, that's just the most energy-efficient way to perform the maneuver. Quite often pilots increase to max-AOA in the low yo-yo to achieve max instantaneous turn rate, while accepting the resulting loss of energy (in the form of speed and/or altitude). You are certainly correct to say that the fighter must increase AOA (and drag) in the descent or gain speed. Whether G increases or not, however, depends on how steep the slope of the lift curve is at that point. Straight-wing prop fighters tend to get more G increase out of a small AOA increase in this AOA region because their lift curves are typically steeper. Also, as you have pointed out, a fighter actually doesn't have to increase G in a low yo-yo to achieve increased turn rate relative to the horizontal plane. As the angle of bank of the fighter increases, more of the G developed goes into the horizontal plane contributing to turn rate, while less is devoted to offseting gravity.
Hope this helps.
Mouse
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Originally posted by Shaw
Once again, sorry for the long reply time. As I've said before, I just don't get many opportunities to check this discussion.
Not a problem, I’m also very busy lately so I can’t check in very often, so I too would like to apologise for the delayed response.
Originally posted by Shaw
There are several exceptions I would take to your comments above:
Rightly so, there are some notable exceptions, so I’ll expand on them where it might be helpful to others.
Originally posted by Shaw
A prop aircraft most certainly CAN perform a nose-low turn (low yo-yo) at full power and best sustained turn speed without increasing speed. I've personally done it in both props and jets, and I'm no magician. The reason is that the prop fighter is NOT at the stall boundary while performing a max sustained turn.
This is the first exception, so let’s see how it occurs. Here are three EM diagrams for WWII fighters that show that for the particular configuration involved in each case, the best sustained turn is indeed at the stall boundary. The RAE engineers state that the best turn with no loss in energy “is flown as close to the stall as possible”. The diagrams shown below are for the British Spitfire, the German Me109 and the American F2A. With reference to the NACA report on the Navy F2A-3 No 01516, the diagrams were correlated with flight tests, the engineers claiming “satisfactory accuracy”. All of these diagrams were published by RAE Farnborough and NACA between 1940 and 1943 and shows the maximum turn rate and smallest turn radius that can be achieved (in a sustained turn) with zero specific excess power (Ps = 0), occurs on the stall boundary.
(http://www.badz.pwp.blueyonder.co.uk/images/Sust1.jpg)
This first image shows that the angle of straight climb (which is the same thing as the Ps = 0 curve) curve increases all the way to the stall boundary, which means that as you get closer and closer to the stall, the sustained turn rate increases, and the sustained turn radius decreases, until the best sustained turn is reached at the point marked M on this first diagram. In practice, depending on the stall/control characteristics of the aircraft and associated risks, one would optimise sustained turns by flying as close to the stall as possible.
(http://www.badz.pwp.blueyonder.co.uk/images/Sust2.jpg)
Here you see a similar situation for the Me109, where the best sustained turn increases all the way to the stall, but in this case, you can see the angle of straight climb curve (Ps = 0) just beginning to level off at the stall boundary.
(http://www.badz.pwp.blueyonder.co.uk/images/Sust3.jpg)
In this EM diagram for a Navy F2A airplane, you notice that the best sustained turn still occurs at the stall boundary, but that the angle of straight climb curve (Ps = 0 curve) is much flatter than the previous examples, which means that flying closer to the stall boundary reduces the sustained turn radius while the sustained turn rate is not as significantly improved. In this case, the optimum sustained turn, remains at the stall boundary.
In the next two EM diagrams we see what happens when the altitude increases, and the power drops as in figure 35. Figure 34 shows that a similar shift in the maximum sustained turn location occurs when flaps are employed.
(http://www.badz.pwp.blueyonder.co.uk/images/Sust4.jpg)
These diagrams now support your previous statement that the maximum sustained turn does not occur at the stall boundary, in these cases it clearly doesn’t. Generally, with more power and less altitude, the Ps = 0 curve increases towards the stall boundary and as altitude increases and power drops the best sustained turn moves away from the stall boundary. The F2A EM diagrams are a good example of where the maximum sustained turn is at the stall boundary and then moves away from the stall boundary significantly as the altitude increases and power drops. This is particularly interesting because the analysis for the F2A confirms both of our assertions, depending on the configuration involved. However, in a simulation context I think the points I made in earlier posts are (due to the modelling) more valid.
Originally posted by Shaw
I'll grant that most prop fighters will gain speed in a full-power split-S even at max-AOA. A low yo-yo in this case may be only a degree or 2 below the plane of the bogie's turn...although most prop fighters can descend much faster than this and still maintain speed.
Agreed, in the example shown above (Fig35) with the F2A at 27,000ft it can maintain its best sustained turn speed at 120mph indicated, by pulling all the way to the stall boundary while descending in the turn at a little over 6 degrees. That confirms your point, but if you take the fight lower with more power available the situation becomes similar to the Spitfire and Me109 diagrams for 12,000ft where the best sustained turn was at the stall boundary. At that point any degree of descent would result in an increase in speed, unless the AoA is increased even further resulting in a disproportionate increase in drag and energy loss. And if the aircraft had sudden or severe stall characteristics the excursion might be even more costly. I’m sure there are prop’ fighters in which it is possible, but not necessarily advisable.
Originally posted by Shaw
Granted it's much closer than the jet is to that boundary, but the prop can still increase AOA and drag above that required for best sustained turn speed. Your diagram is misleading on this point.
In the sense that it only illustrates one set of conditions, as these diagrams must do, I would agree. But it does correctly illustrate the sustained turn behaviour under those conditions, and is generally correct for high powered prop fighters at low to medium altitude, that remain inside the envelope. If I change those conditions by increasing altitude and reducing power, the EM analysis correctly predicts the behaviour you have described. So I wouldn’t say misleading, just not the whole picture. For example in the diagrams below, it can be seen that the Ps = 0 curve exhibits the same behaviour and characteristics as the ones I posted earlier that were originally published by NACA and RAE Farnborough.
(http://www.badz.pwp.blueyonder.co.uk/images/Sust5.jpg)
Now if I increase the altitude and reduce the power, the EM diagram looks like this:
(http://www.badz.pwp.blueyonder.co.uk/images/Sust6.jpg)
Which shows that in that situation the aircraft can hold its best sustained turn speed while descending in the turn at about 4 degrees below the horizontal.
Originally posted by Shaw
Best sustained turn speed for either props or jets is roughly the same as best climb rate speed (Vy). I think you'll agree that Vy is normally well above stall speed (or stall AOA) for props.
Ok, it’s my turn to take an exception. Yes, they are roughly at the same speed, but Vy occurs well above the 1g stall speed, as you say, not above the stall speed at the load factor at which the best sustained turn occurs! I can illustrate that with an EM diagram for two fighters as modelled in AHII as shown below. Notice that the data plate for these two fighters shows that the best sustained turn speed, and the best climb speed are almost the same, as you point out, with only a 2mph difference for the Ki84 and only a 5mph difference for the F6F. However, although the best sustained turn for the Ki84 is well above the 1g stall speed it is at the 3g stall speed! Generally, the best climb speed occurs well away from the 1g stall speed, the best sustained turn may be at roughly the same speed, but at a higher load factor and on the stall boundary, with the exceptions noted earlier regarding altitude and power.
(http://www.badz.pwp.blueyonder.co.uk/images/Sust7.jpg)
The diagrams published by NACA and RAE Farnborough and the indicated behaviour, was known, analysed, and correlated with flight tests, with no shortage of practical minded and experienced pilots able to validate the work. The NACA engineers state that the results of flight tests were correlated with this analysis with satisfactory accuracy. The RAE engineers state that the best turn with no loss in energy “is flown as close to the stall as possible”. Even more importantly, most of the readers on these boards are mainly interested in how this behaviour is reflected in Aces High, and the sustained turning behaviour shown in these diagrams is easy to verify in AH, or almost any other simulation, by carrying out the appropriate flight tests.
For anyone interested, this is an example of the style of Energy Manoeuvrability diagram I’ll be using for the AH2 fighters from now on, including the information on the data plate. If anyone is interested in seeing other data included let me know.
Hope that helps…
Badboy
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Badboy,
Good to hear from you again. Once more, I'm late in checking the posts, and once again I apologize.
The points you make are all quite good. You obviously know what you're talking about. The Brit charts you include surely seem to support your contentions about the best sustained turn rate being at stall speed for prop fighters...at least for the ones shown at low altitudes. Still, that contention does not jive with my experience, so I've done some serious scratching of the head (as well as some other body parts) to try to understand why these charts don't look right to me. Congratulations, you managed to ruin my Easter weekend ;) . (not really, I like this kind of stuff)
So, that being said, I've reached the following conclusions...
The point of intersection of the "angle of straight climb" lines and the "stall boundary" lines obviously depends on the aircraft's thrust (power) versus drag characteristics at high AOA. The more powerful the engine and the slower the increase in induced drag at high AOA slower the speed at which this line begins to drop off. It should certainly be possible to design a fighter with enough power to offset virtually any drag increase. Couple that with poor high-AOA handling qualities, so that the pilot can't actually achieve max AOA, and this pushes the "stall boundary" to the right, resulting in the situation illustrated by your charts. Bottom line is, you certainly could be right for some fighters under some conditions. Whether this should be considered the "standard" case, however, I'm not so sure.
I'm suspicious about the "stall boundaries" depicted in your charts because "stall" is a very subjective term. Some define it as the "break," or minimum controllable airspeed, while some as the first "nibble" of buffet. Although I've never flown the Spit, from what research I've done it appears that it had quite good stall warning (buffet) and could be flown well into the buffet before reaching the real stall break. It also appears that it was seldom flown this way, since the pilots of the day were concerned (probably with good reason) about it's spin characteristics. Anyway, after a little digging, I found some support for this hypothesis. I'd like to match your diagrams with one of my own, but I can't figure out how to insert it here. Anyway, I've got a chart similar to your Spit/Me charts, also from an R&M document contemporary with yours, also at 12kft. (I've also got the ones you posted)
This chart shows a much steeper stall curve than yours, with a min turn radius of 495' at about 120mph vs yours of about 690' at about 160mph. Big difference. At 120mph the "angle of straight climb" curve has started to drop off steeply. This chart shows max sustained turn at about 150mph, some 30mph above stall.
I suspect the difference is that my chart is based on windtunnel data, rather than flight-test data, so that handling qualities and buffet are not considered. I also suspect that the "stall boundaries" in your diagrams are actually "buffet boundaries," the first indication of stall. This is typically where one would expect to find the best sustained turn rate occurring, since the buffet bleeds energy and marks the point at which drag begins to increase rapidly.
So there it is. If the plane is controllable up to max AOA, max turn rate is likely to occur at a somewhat higher speed than actual stall. If you define stall is first buffet, or if the plane is not controllable near max AOA, or if the stall boundary is artificially pushed to the right for some other reason, then it's likely that this will also be close to max sustained turn rate condition. That way we can both be right. ;)
If you'd like to send me your e-mail address or tell me how the heck I can post a JPG on this board, I'd be glad to send you my chart. I'd also be happy to discuss this or other topics with you directly. My address is fciassoc@aol.com. I promise I'm much quicker responding to e-mail. ;)
Best wishes,
Mouse
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Originally posted by Shaw
Anyway, I've got a chart similar to your Spit/Me charts, also from an R&M document contemporary with yours, also at 12kft. (I've also got the ones you posted)
This chart shows a much steeper stall curve than yours, with a min turn radius of 495' at about 120mph vs yours of about 690' at about 160mph. Big difference. At 120mph the "angle of straight climb" curve has started to drop off steeply. This chart shows max sustained turn at about 150mph, some 30mph above stall.
The differences between these charts are caused by the different Clmax value used for the calculations.
Clmax 1,75 for the 495'
Clmax 1,46 for the 695'
There is also some differences in the calcultion methods. The later one is the correct one (the RM 2382 contains corrections for the RM 2381).
Regarding the images; you need some web space somewhere, put the pictures there and then just link them in your post.
gripen
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Originally posted by Shaw
Robert Shaw (Mouse)...no, you haven't seen me online
Never too late to start and I think most people would really like to hear your comments on AH!