Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: udet on October 14, 2002, 12:04:08 PM
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...should try his hand at building a perpetual motion machine. The plane keeps energy in turns and in any maneuver as if drag has never been invented. Plus, it can climb at impossible angles of attack, without stalling, the altimeter spinning wildly.
Is there any real basis for the flight performance simulation of this aircraft???
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Yawn
:rolleyes:
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Originally posted by udet
Is there any real basis for the flight performance simulation of this aircraft???
Yes.
-- Todd/Leviathn
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Yes.
And if anything it can be argued that the Soviet aircraft are under modeled. There are two sets of flight data for most Soviet aircraft and Pyro chose to use the worst of the two. So it could be worse.
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I for one refuse to believe that light aircraft with powerful engines would tend to be fast and accelerate well. That just doesn't make sense does it?
Hooligan
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Then again light aircraft with powefull engines should have some kind of tourqe aswell, La7 doesn't.
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I hope they re-do the cockpit art on both LAs.
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I will get right on the perpetual motion machine once Im done..(http://www3.telus.net/pongo/sept%20007.jpg)
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Now THAT'S a whine. :)
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Pongo Hobbycraft or Gavia?
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Hobby Craft. I am doing it to warm up for the Gavia which I also have. I am saving my AH markings for the Gavia and doing this one as white 18
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whatever :P
The La-7 is better than the Tempest in every respect except armament, but the Tempest is perked and the La7 isn't.
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Your incorrect. The tempest at least has far better perfomance above 10k and far better visibliltiy, One whiner starts a thread saying the Hispano is too tough. the other whiner starts a thread that purports that the hispano doenst matter...
Both are wrong.
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I just don't understand why people start attacking the accuracy of the modelling when it comes to certain planes - especially the La-7 in this case. I'm not a real vet like some of us here, but I believe I've seen through most of the so-called 'important debates' that happened in the presence of this BBS, and while many of them are reasonable, some of them are just outright funny.
To be honest, when it comes to people griping about the La-7, there is a distinct nuance which seems to spew off the scent of "hell, no way Russkies can make something like this. Something's gotta be wrong." Either that, or gross exaggerations of only some of the partial characteristics up to the point that it is virtually meaningless to ask people "if you think so, what exact proof do you have?"
Many people hate the La-7. Honestly, I hate it too. It's an amazing all-around plane at typical MA engagement altitudes. It is among the top three fastest non-perked planes, and armed with 450 rounds of 20mm cannons. Fast, maneuverable and accelerates and climbs very good.
That can be a reason for people "hating it" and yet, it is not a reason to claim that "the FM is wrong". Maybe partial tweaks are needed, like the torque problem Wilbus mentions, but the AH charts seem to match pretty well with the data of this plane hovering around in many sources.
Is it a perpetual motion machine? Nope.
Does the plane keep energy in turns and in any maneuver as if drag has never been invented? Certainly not.
This impression is due to the incredible acceleration of the La-7. It loses energy just like any plane, it just regains them like no other plane around. A 'plain' maneuver won't be enough to dislodge that La-7 embedded at your arse because when you do one maneuver, and have to regain-E from the loss of that maneuver, the La-7 would regain double of the E you would regain.
Typically, when an La-7 engages another target at co-alt, you can assume it is at least 50~100mph faster than the target plane. With good management, it can do loads of cool maneuvers with minimum E-loss - but this is the same with any other plane.
In this aspect the P-51D or the Bf109G-10 is no different. The P-51D accelrates bad at level flight, but with enough altitude, shallow dives will start accelerating the P-51 like mad. If the P-51 has just 5000ft altitude it would escape any enemy. And the Bf109G-10 is almost as incredible as the La-7 in regaining E status thanks to the incredible WEP factor.
Does it climb at impossible angles of attack, without stalling, the altimeter spinning wildly? Of course not. The only planes with these problems are Spitfires and N1K2s, Typhoons and some others, which issue has been discussed without definate conclusions(nobody gave an answer if that is 'realistic' or not) on how they maintain a 100mph climb without being influenced by torque or being destabilized by impending stall.
Is there any real basis for the flight performance simulation of this aircraft??? As Vermillion and Lev said, yes. I've heard some of the discussions on this in the IL-2 boards, with Oleg Maddox answering to almost every question the community asked. There are about 2~3 versions of differing data on VVS planes, and even in IL-2, where the Yaks and La-5FNs are officialy noted as "uber rides", it is modelled with "not the best of data" according to Oleg. Oleg mentioned "If I modelled it with the best of data, even the 1941 LaGG-3 would outperform a Bf109F-4".
....
Besides all of this mentioned, the La-7 has some distinct problems, too. I remember a simular discussion going on MA channel 1 with Mitsu and Wilbus present. Honestly I couldn't understand why Mitsu stated the "La-7 is very stable at low speeds", because, flying mainly 109s, and having experimented with quite a lot of other planes before I decided to fly109s, there is no way that plane can be considered "stable at low speeds". I'm not a hotshot in the La-7, but I can manage it pretty decently. If I would meet a La-7 in a 109G-10, I'd gladly stall-fight it knowing that it would take a pretty good pilot to keep dancing around with the 109 at extreme low speeds. The La-7 is unstable, has a tendency to violent stalls, and sucks at turns and maneuvers at low speeds.
The roll speed is also not very inspiring. Knowing that most of the La-7 pilots out in the MA are pretty much under average, a few good rolls in the Fw190A-5 can turn the tables easily, leaving the La-7 with the only option of disengaging and running away.
And as people duely note, its performance drops off with altitude rapidly. The Beresins and ShVAKS aren't the best of the 20mms when it comes to effective firing ranges, and heavy canopy frames limits rearward visibility even though it is a bubble-canopy plane.
It is a great plane no doubt, but I definately don't think it can be claimed that this plane performs like a UFO.
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Wilbus:
You seem to be asserting that there is something seriously wrong with AH's FM. Would you care to offer some proof, including perhaps some verifiable way to measure torque in AH?
Hooligan
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Torque = Power / Angular Velocity
Not hard to calculate. :)
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I have to say theres only one area id question the FM whilst playing AH and it does seem to happen most when fighting La7s or P51ds.
Basically, I cannot be sure I have the right perception of what 'my' aircraft should be capable of so I cannot really do anything about it in terms of providing data, but this is the situation i often find myself in:
in a high speed dive chasing a P51d and it pulling a very high G reversal,(edge of black out) just a simple shallow dive to hard vertical climb all the way over to inverted (and reversed), rolling 180 degrees and flying level in oppersite direction.
I have had his happen several times where i was chasing in a 190d9 and followed this very maneuvre only to find the P51d literally leaving my plane standing once the reversal is performed.
Now i may have the wrong idea here but i was of the opinion that the 190 had excellent e retention in the vertical and quite an excellent elevator authority which I assume would result in a good retention of speed in a high speed vertical reversal.Perhaps there is the high wing loading kicking in here and under high G it causes massive energy and or speed loss when the P51d with its laminar flow wing doesnt? I certainly would like someone to explain what is happening because its happening all to often lately and i am finding the maneuvre will pretty much always lose me if we start with similar energy states.
Now i DO NOT KNOW if this is the correct outcome but i certainly am constantly surprised by it.I have tried lag pursuit,lead pursuit and pure pursuit to try to keep some speed with the p51 but everytime it accelerates away at such a rate that im left almost standing still.What should i be looking into with this? wingloading,power to weight,high speed slip/e loss etc ? what should i look at to decide if its correct?
This is something that also seems to happen in a sustained high speed turn when fighting LA7s in 109s.if you try to follow in lead pursuit you will never pull enough lead and will lose lots more energy than the la7.If you lag or pure pursuit you also seem to lose lots of ground.Now i realise the 109 isnt the best turner in the world but at high speeds and pulling moderate G the 109 I would have thought would be able to maintain excellent speeds but obviously there must be a factor here that causes the 109 to lose speed quicker than the LA7? is it a high drag factor,high wingload, light weight that causes it to perform so much less in this manouver i wonder or a combination of all three?
I have looked at the various weights and HP of the planes and several other areas but as im no aeronautical engineer Im finding it incredibly hard to know what to factor in to the equation.Can somebody explain both of these situations? kweassa could you help?
btw great post kweassa, i agreed with most if not all of what you say there.
P.s unfortunately i have very little info on the la7 so its almost impossible to investigate it thoroughly, (not that i could anyhow!! :p my maths isnt great!) but as to hooligan saying about light planes with powerfull engines not accelerating well ( i assume he was being sarcastic?:) ) the La5 is empty 6,173lb with 1,650 hp and the 109g6 is 1,475hp at 5,952lb empty so which should in theory be quickest up to say 250-300mph?
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Hazed:
Film an incident when the other plane does something difficult to understand. Since you won't know beforehand when this will happen you will probably just have to film as a matter of course the until you capture an incident. Then use the film viewer to see what is going on in the other cockpit. i.e you will see how hard a turn they really took, how fast they were going, whether they unloaded etc... Then you will understand why it happened or you will find a bug and have film to report it with.
Hooligan
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Take a look at this nice site about the La5 and La7:
http://www.btinternet.com/~fulltilt/Lavochkin.html
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Wilbus:
You seem to be asserting that there is something seriously wrong with AH's FM. Would you care to offer some proof, including perhaps some verifiable way to measure torque in AH?
Hey Hooligan, I'm not good at math so don't know what Funked mean with "Angular Velocity", maybe he can explain :)
However, I find it very odd that a plane such as the LA7, weighting 5840 lbs empty, with a big 1850 HP engine and a (comparable) large prop has LESS tourqe then a Piper Cherokee, weighting 1400 lbs, with 150 HP engine and a small 2 bladed prop.
La7 weights 4 times as much, it has 12 (!!!!!!) Times as many Horsepowers and a much bigger prop. Don't come and tell me this plane would barely be affected by tourqe when a Cherokee is.
Overall, all planes have too little tourqe in AH, actually all planes. 109 and 190 together with Spit 14 has most, most other planes are barely noticable.
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I think that it is MUCH easier to see the E retention problems of various aircraft if you turn the engine OFF. Some of the aircraft (La-7 for example) exhibit the same performance as some of the best modern gliders.:D Now that just aint right.
Spritle
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Wilbus, first you say you don't know what angular velocity is, then you completely contradict yourself and talk with assumed authority on the subject of torque and how incorrectly AH models it.
So if you don't know what angular velocity is, which is a simple physical quantity, how could you possibly know anything about the relatively complex subject of torque?
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funkedup,
You better check your calculations. Your formula is WRONG!
FORCE = Power / Angular Velocity
TORQUE = MOMENT OF INERTIA * ANGULAR ACCELERATION
Better hit the books if you want that A in Physics.
Spritle
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Originally posted by Spritle
funkedup,
You better check your calculations. Your formula is WRONG!
FORCE = Power / Angular Velocity
TORQUE = MOMENT OF INERTIA * ANGULAR ACCELERATION
Better hit the books if you want that A in Physics.
Spritle
Spritle what degree(s) in engineering and physics do you hold and which university(ies) did you get them at? I want to know this so I can be sure not to send my kids there.
Your first equation is just plain wrong. The units don't even work. You've got force units on the left side and work (or torque) units on the right side.
Your second equation is correct, but I am considering a steady state case where RPM is constant, therefore angular acceleration equals zero. In that case the reaction torque on the airframe is equal to power absorbed by the prop divided by the angular velocity of the prop.
PLEASE! :)
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Hazed:
190D-9 vs. P-51D ===========
D9 and -51D have roughly similar max level speeds. They are roughly the same weight as well. Because of these similarities the difference in the wing-span / wing-loading comes to the forefront in performance differences. The D9 has a shorter wingspan that results in higher induced drag. Similar weight+shorter wingspan = higher AoA needed for lift = higher induced drag. This is magnified even more with increasing AoA in maneuvers.
La-7 vs 109 ============
I've done some EM analysis of the La-7 (comparison of the La-7 vs. P-51D for that matter since the La-7 in my experience is the chief nemesis for the Pony and being a Pony driver…well...).
The La-7 has a noticeable advantage in instantaneous turn performance vs. other energy planesets in AH. It also has an outstanding sustained turn advantage against other energy planesets in AH. I'll post my La-7 v P-51D EM chart when I get home later and it will speak for itself. Suffice it to say an outstanding sustained turn characteristic is demonstrative of the La-7's E retention advantage over other "energy" a/c in maneuver. Why? As already mentioned the La-7 profits from a great thrust/weight ratio (there's actually more to it than this but this is a good generalization to explain why the La-7 retains its E so well). When you look at the aerodynamics the La-7 is a pretty dog-gone amazing plane.
Tango, XO
412th FS Braunco Mustangs
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What has always confused me is why is the La7 so much better then the la5fn. Same engine. near same weight. Same wing.....
they are nearly the same plane how can one out perform the other so easily?
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There were some refinements made to the aerodynamics of the La5FN that resulted in the La7. I would assume that there were also some other refinements made concerning any weight issues or what-not, but as I said that is just an assumption.
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Go get the book "LA5/7 Fighters in Action" Explains all differences, too much for me to type here though.
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Cool, another La7 thread.
The more people complain about it the more people fly it...that's ok in my book...just means more of them to kill, and damn near every one of 'em is an easy kill....bring them on!!!
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Pongo:
Difference in parasite drag. The La-7 airframe is much cleaner aerodynamically.
Thus, the designers engaged in a program to further lighten the airframe by the substitution of aluminum structures for the main spar and other parts of the design wherever possible, as well as a general cleaning-up of the airframe. The result was the La-7, which first appeared in prototype form in January, 1944. With the airframe gaps sealed, a different propeller, and the engine oil cooler removed from the drag-producing position atop the engine cowling to a neat scoop under the fuselage, the wheel wells covered completely, and a different exhaust cover, maximum speed was increased to 407 m.p.h at 15,000 ft. - over 40 m.p.h. faster than the La-5FN - making the La-7 the fastest of all Soviet fighters to see service during the war.
Here's the link for the quote: La-7 link (http://m2reviews.cnsi.net/reviews/allies/ussr/cleaverla7.htm)
Here's another link:
La-7 link 2 (http://www.militarymuseum.cz/english/letecke_muzeum/lavockin.html)
Tango, XO
412th FS Braunco Mustangs
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just a note..have noticed my 51 reverses alot faster with 1 click down flaps and cut trottle when starting to pull out
Also the 38 WILL hang at low alt and speed with zeke:D :D
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funkedup,
Please break down your equation
Torque = Power / Angular Velocity
into it's base units of measure. Please show your work as this is for a grade. :p
Spritle
edit: Added words "of measure"
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Originally posted by Spritle
funkedup,
Please break down your equation
Torque = Power / Angular Velocity
into it's base units. Please show your work as this is for a grade. :p
Spritle
In SI units:
[N*m] = [N*m/s] / [1/s]
[N*m] = [N*m] * [1/s] / [1/s]
[N*m] = [N*m]
:)
Show me your diploma(s), I'm taking this to the dean!!!!!!!!!
:)
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funkedup,
[N*m] = [N*m/s] / [1/s]
WRONG!
What the hell is 1 in your equation?
You are saying 1/s = Angular Velocity !!!!!
1 what ? 1 needs a unit. In this case either degrees or radians.
You sure you want to take that to the dean? He will probably give you an F ;)
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Spritle, if you are using natural units (radians) then you don't put a unit on angular measures.
For instance, the length "s" of an arc is:
s = theta * r
where theta is the included angle and r is the radius.
Analyze the units
[m] = [1] * [m]
Theta is dimensionless - measured in natural units (radians). So you use a 1.
If we explicitly put radians in there the dimensional analysis would look this:
[m] = [radians] * [m]
Which is an inequality.
And in case you you doubt the equation (s = theta * r ) is true, consider an arc with included angle 2*pi, also known as a circle
s = 2*pi * r = pi*D (where 2*r = D, the diameter)
The result is also known as the circumference of a circle. I'm sure you've seen circumference = pi*D in elementary geometry studies. If not, get something round, measure its diameter, then wrap a string around it, mark the circumference on the string, unwrap it, measure the circumference, and calculate the radio of the circumference to the diameter.
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Good intro to angular motion here: http://www.udallas.edu/physics/GP1/rotationalmotion_faqs.htm
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CAT FIGHT!
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funkedup,
Consider a circle with a diameter X. How many radians are in that circle? How many degrees?
Angular velocity is NOT described as 1/s. It is expressed as degrees per second or radians per second.
You must be talking about theoretical math. No engineering text in the world uses your 1/s to define angular velocity. Sorry bub you lose.
1/s describes nothing. Give me the angular velocity of a 12 foot diameter prop turning 1200 rpm.
Nice try on the link too. It looks like you didn't understand what they were saying.
Here is a quote right from their page:
Do you always have to use units of radians per second for angular velocity?
There are many units for angular velocity. One of the most common is rpm, which stands for revolutions per minute (rev/min). In principle, any consistent set of units works for describing the kinematics of rotation. However, you will also want to describe the dynamics of rotation and to do that you must use radians per second (rad/s) for the units of angular velocity. Some advice: Get into the habit of immediately changing the units of all angular velocities to radians per second as the very first thing you do when you start to solve a problem.
Perhaps you were thinking rev was unitless. I'm not sure where you got that from 1 rev = 360 degrees = 2*pi*radians
Spritle
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Originally posted by Wilbus
CAT FIGHT!
It's a nerd fight actually. :D
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Originally posted by Spritle
funkedup,
Consider a circle with a diameter X. How many radians are in that circle? How many degrees?
Angular velocity is NOT described as 1/s. It is expressed as degrees per second or radians per second.
You must be talking about theoretical math. No engineering text in the world uses your 1/s to define angular velocity. Sorry bub you lose.
1/s describes nothing. Give me the angular velocity of a 12 foot diameter prop turning 1200 rpm.
Nice try on the link too. It looks like you didn't understand what they were saying.
Here is a quote right from their page:
Do you always have to use units of radians per second for angular velocity?
There are many units for angular velocity. One of the most common is rpm, which stands for revolutions per minute (rev/min). In principle, any consistent set of units works for describing the kinematics of rotation. However, you will also want to describe the dynamics of rotation and to do that you must use radians per second (rad/s) for the units of angular velocity. Some advice: Get into the habit of immediately changing the units of all angular velocities to radians per second as the very first thing you do when you start to solve a problem.
Perhaps you were thinking rev was unitless. I'm not sure where you got that from 1 rev = 360 degrees = 2*pi*radians
Spritle
Spritle - you can write the natural angles as radians but when you do dimensional analysis you ignore the radians, as I demonstrated with the arc length equation.
s = theta * r
[m] = [1 ]* [m]
If we do it your way, and use radians, we get:
[m] = [rad] * [m]
Which is an inequality, and therefore incorrect.
PS The 1/s notation is quite commonly used in textbooks for angular velocity and frequency measurements.
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Originally posted by funkedup
Show me your diploma(s), I'm taking this to the dean!!!!!!!!!
:)
If it helps, I'm a college lecturer, and so far funkedup is 10/10 :)
Badboy
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hehehe-lots of people got excited about this one.
I don't know much about the real La-7, but I figured this would get ppl fired up :)
None of my books about WW2 A/C has any info on it, only on the La5. But I still think that in AH, La-7 is faster than the Tempest in level flight at sea level.
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It isn't, it just accelerates faster, so it will catch a Tempest in a race starting from speed X to speed Y.
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Here's an EM Diagram - La-7 vs. P-51D
(25% fuel, sea level alt, military power)
(http://www.thetongsweb.com/AH/images/la7-v-p51d.jpg)
A lot of info there but the one thing I'd like point out above is the sustained turn rate curves. Note that the La-7 has a better sustained turn vs. the P-51D. One implication is at co-alt, co-speed the La-7 can be pulling near 3 g's sustained without bleeding any E while the P-51D would be losing E trying to match the La-7's turn at 3 g's.
The moral of the story is that just because you're burning E doesn't mean the other a/c is and that judging E states can be a really tricky thing leading to some nasty consequences.
Tango, XO
412th FS Braunco Mustangs
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Tango where did you get that? Is it based on AH empirical data, real world empirical data, or calculations?
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dtango PLEASE PLEASE PLEASE add the 190d9 to that chart?
i would be hugely gratefull and i'll promise never to shoot at you in the game :D if i do ill imediately auger with a huge appology! hehe
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Just so it's clear, I didn't just put that EM chart together. I've had it for awhile and it took quite a bit to put it together. Didn't want to give the impression that I just worked on it for 30 min and then voila.
Funked -
Airframe data just from whatever sources I could find. Base performance data from AH flight tests. Both sets of data used in multistage calculations. Methodology reviewed by Wells (bless his soul :) ).
Not sure if I'm using the same methodology as Badboy but I wanted to give him a chance to finish his charts before comparing notes with him.
Hazed -
believe me it takes quite a bit of work- multiple steps involved in the process, all needing double and triple QA passes to make sure you've got good info. Then the charts are only good for a given set of flight parameters. I barely have time to fly in my free time as it is :)! I'll see what I can do but it may take awhile. I don't intend to post other charts but would rather wait to see the full set that Badboy publishes when he is done. However if I put a D9 chart together I will share it.
Tango, XO
412th FS Braunco Mustangs
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:confused:
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Wilbus:
There are no piper cherokee's in AH to compare the La-7 to. And the controls in AH aren't really connected via rods and cables to alierons etc... so you don't "feel" the aircraft the way you do in real life. Your comparison is meaningless. Now if you took a stopwatch, trimmed the rudder to neutral on takeoff and measured yaw with neutral controls then you might have some actual data for comparison. Right now all you are saying is that it doesn't "feel" right to you. if you want to show some error in the flight model you are going to have to perform measurements and make some calculations (that icky math thing again) and compare that data to real life Lagg data. Otherwise you are just pouting because the game modelling does not match your baseless opinion.
Hooligan
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My Masters degree in Applied Physics says Funked is spot on. :)
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funkedup,
I will concede that you are correct however please explain the following problem.
Given an electric motor at 1000 rpm and 3HP what is the Torque of the motor?
Give your answer in SI units. Show your work and explain the units that you use for angular velocity.
Spritle
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Back to Lame-7.
When in 190, it is the plane I hate most (together with C-Hog and Tempest). It runs down even the Dora, outperforms it in most categories and is is one of vulchee's favourites.
Even when being one of the most common vulchee planes, it maintains K/D above 1. That speaks a lot.
A cheap perk, 5 perkies, I'd say.
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I agree Hristo, the 190d9 should be perked.
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...and P-51D
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LOL, it takes so little to start a perk-it discussion ;)
Dunno, I have rarely seen D-9 and P51 suicide takeoffs from vulched fields. Not so with Lame-7s. That speaks something. Don't underestimate the dweeb factor - they are very good in discovering their rides ;).
Wanna perk D-9 ? No problem with me. Whenever I flew the thing I had K/D which would never rob me of it. But generally, it would make a fairly rare arena plane even more rare.
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Wanna perk D-9 ? No problem with me. Whenever I flew the thing I had K/D which would never rob me of it. But generally, it would make a fairly rare arena plane even more rare.
You what? That's utter BS. Last tour the D9 ranked 7th in terms of number of kills attributed to it, ahead of the 109 G10, F6F, P-38, both the 190 A5 and A8, any of the F4Us, or Jugs or Yaks.
It didn't get that number of kills, sat in the hangar. Rare? lol!
BTW, Spit9 and P-51D are both ahead of La-7 in number of kills... what does that tell you?
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Funked:
What are you going to charge this guy for the private tutoring service?
Hooligan
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La-7 is an outstanding fighter...I agree about it.
but I feel AH's one is wrong in something....
In real life, La-7 was bad (unstable) at takeoff/landing.
Doesn't it mean La7 had a bad handling at slow speed?
and it had a tight tapered wing, doesn't it have bad wing-tip stalls?
AH's one is really stable at low speed....easy handling...too easy to recover from spin. I feel it is strange.
In the second place, La-7 can accelerate to the top speed like a rocket. But its engine diameter is big. Doesn't it have a large profile drag? (I mean drag setting might have error in La-7...)
Thirdly, La-7 can fly and fight without 1/2 wing very easily. Actually I shot down bandits with it. Is this model correct?
OK Mitsu out...Sorry for poor English. :(
P.S
This is whine though...I hate to see some pilots do a high -G loop in La-7. :( It's pretty weird....
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funkedup,
Nevermind I figured it out. :eek:
Spritle
P.S. to all the other Brainiacs that chimed in with their little quips :p
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Originally posted by dtango
Here's an EM Diagram - La-7 vs. P-51D
(snip)
Well, there is a real world tested flight envelope (http://naca.larc.nasa.gov/reports/1948/naca-tn-1719/index.cgi?page0017.gif) available for the P-51. AH is a game with a generalized flight model...
gripen
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Originally posted by Dowding (Work)
You what? That's utter BS. Last tour the D9 ranked 7th in terms of number of kills attributed to it, ahead of the 109 G10, F6F, P-38, both the 190 A5 and A8, any of the F4Us, or Jugs or Yaks.
It didn't get that number of kills, sat in the hangar. Rare? lol!
7th ? Quite average for one of 3 best fighters of the war.
Originally posted by Dowding (Work)
BTW, Spit9 and P-51D are both ahead of La-7 in number of kills... what does that tell you?
That popular planes from movies are popular planes in game. I'd be more interested in their K/D, compared to Lame-7.
As for perking, yes, I have nothing against perking all three : Lame-7, P51D and D-9. They all have their earlier varients to be flown freely.
On the other hand, who cares ;).
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funkedup,
Earlier in our discussion you said this:
I am considering a steady state case where RPM is constant, therefore angular acceleration equals zero. In that case the reaction torque on the airframe is equal to power absorbed by the prop divided by the angular velocity of the prop./
While this is a valid statement I don’t think this is the regime of flight that anyone had in mind. Most of the people that are complaining about the La-7 are talking about torque with respect to rapid turning during scissors type maneuvers. While engine RPM should remain fairly constant shouldn't there be a force imparted on the airframe by the spinning prop as it is rotated about axis of the turn? Not sure if that makes since.
Hooligan said this:
There are no piper cherokee's in AH to compare the La-7 to. And the controls in AH aren't really connected via rods and cables to alierons etc... so you don't "feel" the aircraft the way you do in real life.
I would counter with this. You also don’t feel black outs or red outs while sitting in your chair yet they are modeled. You also don’t feel that .50 cal ripping through your chest yet it is modeled. You also don’t feel an impending stall yet there is a stall horn blaring away. Torque should and can be modeled.
Also I’m not sure if this is modeled, but shouldn’t some aircraft turn better in one direction than the other?
Mitsu mentioned the possibility of the drag being off for the La-7. I do know that it seems to glide better than any other aircraft in the game. And it will hang on to 300mph in a glide without loosing much altitude either.
Spritle
edit: can't get two quotes to work
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Spritle / Mitsu: ====================
With all due respect guys, if you have an issue with the flight model the burden of proof is for you to come up with the quantitative technical anaylsis to demonstrate the issue. Any serious analysis of flight models needs to start here. Without it we just perpetuate lots of unsubstantiated myths about AH which does nothing but erode confidence in the FM's for those who don't know any better.
How do you know the La-7 form drag is off? How do you know that there is something wrong with the glide characteristics of the La-7? If they are off then please provide the aerodynamic analysis that shows they are.
Others with the background in aerodynamics and flight models certainly have analyzed AH over the years and haven't lost confidence in the FM's. I can say from my personal expsosure to analyzing EM characteristics of AH a/c that my confidence level as to how HTC models their a/c has greatly increased. They are pretty thorough and from what I can tell are pretty meticulous and careful about how they design the FM's.
Gripen: =================
Thanks for the NACA link. The data however is for measuring buffeting tail loads and unfortunately not useful for EM analysis.
Tango, XO
412th FS Braunco Mustangs
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Spritle I'm glad you figured it out! When I was teaching I used to get the same exact questions about radians.
shouldn't there be a force imparted on the airframe by the spinning prop as it is rotated about axis of the turn? Not sure if that makes since.
Yes you are correct. Angular acceleration is a vector quantity. So you can get a torque reaction in more than one way.
One way is as you mentioned before, by changing the magnitude of the angular velocity. The reaction is equal to the moment of inertia times the angular acceleration, like you stated before.
The other way is by changing the orientation of the angular velocity vector, i.e. pitching or yawing motions. For example, let's picture a single engine aircraft with "normal" (clockwise as viewed by the pilot) prop rotation. By the right hand rule, this means the angular velocity vector of the prop/gearbox/engine rotating machinery points forward. Pitching the aircraft nose-downward will tilt the angular velocity vector rotating parts downward. The net change in angular velocity will be a vector pointing roughly straight down. The reaction on the aircraft is in the opposite direction, pointing straight up. And by the right hand rule, this reaction will impart a left-turning moment on the aircraft.
Likewise:
Pitching up will cause a right-turning tendency.
Yawing left will cause a pitching-up tendency.
Yawing right will cause a pitching-down tendency.
And you can definitely observe this behavior in AH. Whether or not the strength of the behavior is correct, is beyond my knowledge to judge or test. But the behavior is definitely "there".
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dtango,
The flight envelope (http://naca.larc.nasa.gov/reports/1948/naca-tn-1719/index.cgi?page0017.gif) tells directly practical maneuvering region of the P-51D at given weight. You can use it directly for EM analyses, please read the report (http://naca.larc.nasa.gov/reports/1948/naca-tn-1719/) .
gripen
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my phd in gut reactions says funked is dead on too.
I think I remember Calculus Based Physics in college.... If I remember correctly that was the 2.5 hour nap I had twice a week for 2 semesters of my senior year....
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Spritle:
You misunderstood my post. Torque is modeled in AH. My point is that just because a player doesn't "feel" torque in AH they way they would in a piper cub, this does not mean that torque is not modeled. Just as (and thank you for the nicely illustrative example) a player doesn’t “feel” a .50 round ripping through their chest in AH like they would in the real world, this does not mean that weapons effects are not modeled in the game.
Hooligan
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Adding to Hooligan's comments:
Remember that "torque" and all the other destabilizing forces caused by the propulsion system are opposed by the natural stability of the airplane. Dihedral, wing sweep, and most importantly, tail surfaces, all tend to stabilize the airplane.
The effects you feel will be a result of the tug of war between all of these factors. Even if the propulsion side effects are perfectly modeled, a small variation in the stabilizing effects will give you a different feeling of what the plane is doing.
One thing that works in favor of a high-powered aircraft is the fact that the propwash significantly increases the effectiveness of the tail surfaces, especially at low airspeeds. Is it modeled perfectly in AH? I don't know, and I don't have the time to devise a quantitative means of determining the answer.
I will note one thing: In my reading of handling qualities evaluations and pilot's manuals for many WW2 fighters, there is a trend: the aircraft were supposedly easier to recover from a stall or spin with the throttle at idle. But in AH I have found that going to idle makes the planes less stable and harder to recover. The most rapid recoveries, even in a nose-up attitude, are obtained with full power.
Which tends to support the idea that the stabilizing effects of propwash in the game could be a little too strong. But it's a subjective observation in the game compared to second-hand subjective observations from real life, so I'm not prepared to start telling HTC that all of their painstakingly prepared mathematical models are faulty.
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Unit Analysis?!!!
FunkedUp, you geek :D
I don't know how many times that saved my butt on a test!
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Originally posted by hazed-
dtango PLEASE PLEASE PLEASE add the 190d9 to that chart?
i would be hugely gratefull and i'll promise never to shoot at you in the game :D if i do ill imediately auger with a huge appology! hehe
Hmm does that deal apply to me also?
Here is my EM analysis with the D9 added to the La7 v P-51 comparison for the AH flight model.
(http://www.badz.pwp.blueyonder.co.uk/Files/Images/AH-La7-P51D-Fw190D9.jpg)
Hope that helps...
Badboy
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gripen: I'll digest the report.
Badboy: :D thank you sir.
Tango, XO
412th FS Braunco Mustangs
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dtango,
Also this (http://naca.larc.nasa.gov/reports/1946/naca-tn-1044/) report contains additional information. You can see that the shape of the flight envelope of the Mustang (or other planes with similar wing profiles) is different than in the case of the earlier wing profiles. Therefore it's easy to figure out that there is something wrong in your or Badboy's EM curves in the case of the P-51D if compared to the real world data. Anyway, for this game those EM curves are OK; we can't except perfect flight model.
gripen
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Originally posted by Hooligan
Wilbus:
You seem to be asserting that there is something seriously wrong with AH's FM. Would you care to offer some proof, including perhaps some verifiable way to measure torque in AH?
Hooligan
:rolleyes:
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Originally posted by gripen
Therefore it's easy to figure out that there is something wrong in your or Badboy's EM curves in the case of the P-51D if compared to the real world data.
gripen
Hi Gripen,
I use a flight model in my analysis that allows me to add or omit various aerodynamic effects so that I can use it for different flight simulations, and the one I use for performance analysis of real world aircraft includes every relevant factor. If I compare the results with a simplified model, one that does not include the reduction in lift due to compressible flow, and does not include the increase in lift due to thrust or prop wash, the resulting curves are almost identical. It is, therefore, hardly surprising that some developers choose not to model those things at all. However, there isn’t anything wrong with the EM curves I’ve produced for any of the Aces High aircraft, based on extracted data, or the ones I’ve produced based on real world data.
The fact is that changes in the various coefficients are somewhat masked when the large number of parameters involved are all merged together numerically to produce the curves. I know this because the effects described in those reports have been included in my analysis and only appear to make a negligible difference to the EM curves for prop fighters, and in practice the reduction in the coefficient of lift due to compressible flow appear to be masked, to some extent, by other effects that increase the coefficient of lift, such as the contributions to lift from thrust and propwash, so that although those things have been modelled, they aren’t at all obvious on that type of diagram. In order to illustrate that I’ve attached an example of an EM analysis that shows the influence that Mach number would have on EM curves for a prop and subsonic jet.
(http://www.badz.pwp.blueyonder.co.uk/Files/Images/CompFlow-EM.jpg)
This diagram was originally produced to help show how those factors influenced the variation in turn radius and explains why Shaw refers to a minimum turn radius that occurs below corner velocity, while most prop fighters have their minimum turn radius at their corner velocity. That happens because the results of the factors mentioned in those reports are more noticeable in the jet due to the higher Mach numbers involved, after all, its corner velocity is comparable with the maximum speed for the prop fighter. In the prop fighter the difference in corner speed, for example, caused by this is typically only in the order of a few mph, as you can see in the diagram, but in practice the factors I mentioned previously mask that shift and translate the curves back towards their original positions. I believe it would be impossible to see that anything was wrong with the curves on any of the relatively slow prop fighters by inspection. Even on the supersonic jets it takes dramatic variations in the various aerodynamic coefficients, such as those that occur in the transonic region, to distort the curves in a significant and readily noticeable way.
Badboy
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Originally posted by dtango
Badboy: :D thank you sir.
Tango, XO
412th FS Braunco Mustangs
You are welcome.
Looks like Hazed is still gonna shoot me down without augering after though, despite the D9 info :)
Badboy
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Badboy,
I'm merely pointing out that real world data in the case of the P-51 (or other planes with similar profiles) shows different shape of flight envelope than in the case of the planes with older profiles. You can see the phenomena from the sources I claimed above. And if we look your AH data above (La-7, P-51D, Fw 190D) we can't see that phenomena (all curves are similar). It should be noted that phenomena (different shape of Clmax curve) shows up at entire speed range so it is not limited to compressebility speeds as you are trying to prove above (typical jet vs typical prop graph). So, there is indeed something wrong in the P-51 vs other comparison you posted above if compared to real world data.
Anyway, your data clearly states that it's for a simulation (AH) so I have nothing to complain in that case but dtango posted data without a claim about source.
gripen
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As for low speed handling. Lame-5Fn and Lame-7 had leading edge slats, just like 109. This is not visible in AH, but modeled in Il-2.
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Great work Badboy!
How about 15k and/or 30k EM analysis with the D9 added to the La7 v P-51?
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Originally posted by funkedup
I'm not prepared to start telling HTC that all of their painstakingly prepared mathematical models are faulty.
pfff
in fact it's quite easy : just change your usual RAF ride for a 109 or a 190 during one month and you would be ready to do so :D
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gripen:
I thought I stated that my performance information came from flight tests of AH a/c as I was replying to funked. The objective of my EM chart certainly wasn't meant to check AH FM's but to help explain how that pesky La-7 does what it does ;).
Anyhow your point is taken. I am very much using a simplified model for the lift limit calculations for the flight envelope simply based on AH stall speed of an a/c.
Thanks for both reports. Digested the first. Interesting data. If HTC modelled the P-51D with data from the 1st report, there would be a lot of screaming for sure from pony haters! Of course there's some puzzling stuff there as well. But I guess that's real life. Admittedly some of it is over my head. Haven't looked over the 2nd since it's a bit longer.
Tango, XO
412th FS Braunco Mustangs
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Did anyone read the article at simhq a few weeks ago about EM diagrams? It compared the EM diagrams from the AH P-51D to the Microsoft Combat Flight Sim P-51D. Now at first this might sound ridiculous, but what the article tried to explain is this. Even though the diagrams were different both P-51D's performed similarly against their respective opponents from each game. Does that make since?
So if you compare the EM diagram from the AH P-51D to that of the AH Fw190 there is some ratio of difference. As long as the same ratio existed between the MSCFS P-51D vs. MSCFS Fw190 then it really didn't matter that the EM diagrams don't match cross platform, as the aircraft would perform correctly against one another within the same game. This is especially true since you can't fly an AH P-51D against a MSCFS Fw190.
So really it's not THAT important that the flight models have 100% fidelity compared to their real world counterparts, but rather that they maintain their historical difference with their SIMULATED adversaries. This would indicate that there needs to be some base EM diagram that ALL other aircraft models MUST maintain their historical difference against.
This makes the already difficult task of comparing real world test data for an aircraft to AH flight numbers for a different aircraft and then stating “there is an error” impossible. Instead ALL real world data MUST be converted to SIM data based on that BASELINE EM diagram mentioned earlier.
Here is the link to the article.
http://www.simhq.com/simhq3/sims/air_combat/skills/
Spritle
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Spritle - Don't know if you knew or not but Badboy who is posting here wrote that article.
Tango, XO
412th FS Braunco Mustangs
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Originally posted by Mitsu
La-7 is an outstanding fighter...I agree about it.
but I feel AH's one is wrong in something....
In real life, La-7 was bad (unstable) at takeoff/landing.
Doesn't it mean La7 had a bad handling at slow speed?
and it had a tight tapered wing, doesn't it have bad wing-tip stalls?
AH's one is really stable at low speed....easy handling...too easy to recover from spin. I feel it is strange.
In the second place, La-7 can accelerate to the top speed like a rocket. But its engine diameter is big. Doesn't it have a large profile drag? (I mean drag setting might have error in La-7...)
Thirdly, La-7 can fly and fight without 1/2 wing very easily. Actually I shot down bandits with it. Is this model correct?
OK Mitsu out...Sorry for poor English. :(
P.S
This is whine though...I hate to see some pilots do a high -G loop in La-7. :( It's pretty weird....
agree with some of Mitsu here........both La 5 and La7 had a very disconcerting landing and take of "bounce"(la 7 more so)......... Czech pilots used to Spitfires had to be trained not to correct for it as they did with lesser bounce from Spitfires...........
AH is in error re the stall speed IMHO.......the La7 pilot was instructed that the proper landing speed was 137 Km /hour thats approx 85mph........try it! I do not know what the true departure point speed was for near level low alt but I am sure it was lower than the recomended landing speed!
Leading edge slats lowered the departure speed with the characturistic rapid departure at that lower point. But it was considered "easy" (by ex spitfire pilots) to recover.
Engine off drag seems low in all AH planes to me..........(un qualified opinion)
But the nose down engine off/throttled back acceleration of the La7 seems high even tho it is the smallest and has the lowest total drag of all the radial engined fighters.
Its elevator and rudder control surfaces were massive in comparison with wing and tail areas and would have an abnormal affect of drag during manouvering.
However Verm is correct IMO that the climb, accel and top speed are certainly not over modelled.......
If it were down to me (and of course it is not) I would be increasing both the drag and thrust side of the model....... but retaining the drop off in thrust with alt...and adding a bit more stability at below 100mph with a rapid departure and bouncy landing.
thx for the diagram badz........copied
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Originally posted by gripen
Badboy,
I'm merely pointing out that real world data in the case of the P-51 (or other planes with similar profiles) shows different shape of flight envelope than in the case of the planes with older profiles. You can see the phenomena from the sources I claimed above.
Gripen,
Of course I'm familiar with that material, almost any first year undergraduate would be perfectly aware of the dependence of the aerodynamic coefficients on Mach and Reynolds Number. However, you seem to be expecting that to have an influence on the EM diagram that should be obvious, I've pointed out that I have both types, including many real EM diagrams produced by the military and the difference isn't obvious at all.
And if we look your AH data above (La-7, P-51D, Fw 190D) we can't see that phenomena (all curves are similar). It should be noted that phenomena (different shape of Clmax curve) shows up at entire speed range so it is not limited to compressebility speeds as you are trying to prove above (typical jet vs typical prop graph). So, there is indeed something wrong in the P-51 vs other comparison you posted above if compared to real world data.
I wasn't trying to prove anything, indeed, why would I try to prove something that was already common knowledge? I have been referring to the variation in the aerodynamic coefficients as a function of Mach and Reynolds number, and although it might not sound like it, that's exactly what that report is discussing. Those Mach effects are the result of compressible flow, and you appear to be misunderstanding the influence that would have on the EM analysis, and my explanation of it.
The EM diagrams for the real aircraft are infact very similar to those shown here for Aces High, and I've already explained why. I don't know what difference you are expecting to see, and I suspect you don't either? The fact remains that even with all those factors included in the model, the similarity to the AH EM diagrams is almost breathtaking!
Badboy
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All this mathematical torque stuff is way over my head. I'm lucky if I can tie my shoes without getting my finger stuck.
But isn't there a difference between calculating torque correctly and applying the resultant force to the FM? I'm specifically thinking about the fact that we can take off from a CV in a F4U-4 without using any rudder correction at all. The FM may calculate the torque #'s correctly, but whatever it does with those #'s doesn't seem to affect flight characteristics much.
ra
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Badboy:
I think one of the things gripen was trying to point out from the 1st report was that according to the v-n type diagram in the report the P-51D lift-limit envelope is different from what we have on our EM charts. Here is the chart. (http://naca.larc.nasa.gov/reports/1948/naca-tn-1719/index.cgi?page0017.gif)
I can't quite explain that since I'm a little perplexed as to how the specific graph in question was put together though the report I think basically says that the v-n diagram in question was based on flying the a/c to it's buffet/stall limits.
What I can't explain either is if for instance the sea level chart is correct then the P-51D in that report has a much better instantaneous turn capability then what our EM charts indicate. E.g. at sea level near mach .2 (~150 mph) the P-51D has a lift limit of 3g's according to the chart. With this info using the simple equation of Vstall-turn = Vstall * sqrt (gload), I end up with a level stall speed for the P-51D at ~88mph ASL.
Still mulling over it all.
Tango, XO
412th FS Braunco Mustangs
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Badboy,
We can clearly see that in your P-51/La-7/Fw 190D chart all slopes are very similar and ratio between planes stays constant at hole speed range. We also know that atleast the La-7 utilized NACA 230 series profile and IIRC the Fw 190 used NACA 2something profile too. If we look NACA data we can see that the P-51 had very different Clmax curve shape if compared to the planes which utilized NACA 230 profile. This difference should certainly show up as atleast varying ratio between planes ie as speed increases the P-51 does relatively better (real world data v-g curve comparison between the P-51 and P-38 or P-47 or F4U shows this difference quite clearly, data mostly from manuals). For one reason or another this difference does not show up in your comparison. BTW how many times I should explain this issue? Does this difference show up in your numerical values if we can't see it from the graph?
gripen
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I don't complain about the La-7. Every plane has disadvantages and advantages. I have never landed a La-7, a 109 is easier to land than La-7, and La-7 seems to have very high stall speed. Also, I cannot hit anyone with it's guns when they are moving around a lot, sure, it has powerfull guns but the guns don't shoot in a nice even stream but all over the place, not a lot of ammo either. And I don't see a lot of people flying the La-7, everybody seems to be flyings spits, typhoons or those japaneese planes.
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Originally posted by gripen
Badboy,
For one reason or another this difference does not show up in your comparison.
I’ve already explained that in a previous post.
BTW how many times I should explain this issue? Does this difference show up in your numerical values if we can't see it from the graph?
I’ve already explained that too. But if you want to verify it, I can only suggest you carry out your own EM analysis taking all those factors into account, and then, when you have results similar to mine, as indeed you will, you probably won’t even believe it then. But you will at least be able to re-read my previous posts and it may all make a little more sense to you.
Meanwhile, you can rest assured, the Aces High diagrams are both correct and accurate!
Badboy
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Originally posted by dtango
Badboy:
I think one of the things gripen was trying to point out from the 1st report was that according to the v-n type diagram in the report the P-51D lift-limit envelope is different from what we have on our EM charts. Here is the chart. (http://naca.larc.nasa.gov/reports/1948/naca-tn-1719/index.cgi?page0017.gif)
Ohh boy, where to begin?
The first thing you must remember, is that the envelope shown on an EM diagram doesn’t have hard boundaries because an aircraft can fly outside of the envelope if forced to do so. In aircraft with manual pitch control, if enough control power exists, it is possible for the pilot to generate enough pitch acceleration to force a g overshoot, simply put, he can pull back fast enough on the stick to force the aircraft outside of the envelope, and generate greater loading than would be possible in steady state conditions. That is what’s happening in the report. Basically, the report isn’t showing you the type of v-n diagram you think it is, it isn’t showing you the aircraft envelope at all, and it isn’t showing you the lift limit, it is showing you a buffet boundary, that in most cases has been reached by taking the aircraft outside the envelope and then into post stall conditions.
I can't quite explain that since I'm a little perplexed as to how the specific graph in question was put together though the report I think basically says that the v-n diagram in question was based on flying the a/c to it's buffet/stall limits.
It was based on the buffet boundary, not the stall limit, there isn’t really any such thing as a stall “limit” it’s more like a region of the envelope, it is possible to fly in it, or beyond it, how far beyond the stall you go will depend on the pitch rate on the aircraft when you get there.
What I can't explain either is if for instance the sea level chart is correct then the P-51D in that report has a much better instantaneous turn capability then what our EM charts indicate. E.g. at sea level near mach .2 (~150 mph) the P-51D has a lift limit of 3g's according to the chart. With this info using the simple equation of Vstall-turn = Vstall * sqrt (gload), I end up with a level stall speed for the P-51D at ~88mph ASL.
Still mulling over it all.
You can’t base performance calculations on transient conditions that exist briefly outside the aircrafts normal envelope… Correction, you can, but it just wouldn’t have any useful meaning in terms of air combat.
Hope that helps
Badboy
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Originally posted by Xjazz
Great work Badboy!
How about 15k and/or 30k EM analysis with the D9 added to the La7 v P-51?
Thanks.
Certainly, keep your eyes open at SimHQ, there are lots of great things in store for the future!
Badboy
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Badboy,
So far you have explained following:
"The fact is that changes in the various coefficients are somewhat masked when the large number of parameters involved are all merged together numerically to produce the curves. I know this because the effects described in those reports have been included in my analysis and only appear to make a negligible difference to the EM curves for prop fighters, and in practice the reduction in the coefficient of lift due to compressible flow appear to be masked, to some extent, by other effects that increase the coefficient of lift, such as the contributions to lift from thrust and propwash, so that although those things have been modelled, they aren’t at all obvious on that type of diagram."
Well, some effects might be masked but this Clmax difference can be clearly seen from the real world test data which certainly contain all masking effects. In the case of the P-51 clmax difference if compared to other fighters is far more than "negligible". In practice at 30k the P-51 could pull more than 1g more instantaneous at high speed than competion. At sealevel difference is small but as can be seen from the NACA data, the difference exists there too. Basicly by limiting your analysis to sealevel you miss one of the main points which made the P-51 so succesfull.
You should also study very carefully that NACA 1719, specially graphs which explains when buffeting starts. You can also compare it to other real world data.
gripen
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Originally posted by Badboy
Basically, the report isn’t showing you the type of v-n diagram you think it is, it isn’t showing you the aircraft envelope at all, and it isn’t showing you the lift limit, it is showing you a buffet boundary, that in most cases has been reached by taking the aircraft outside the envelope and then into post stall conditions.
As I read it, it's only for the tail, not the wing or the whole aircraft? None of the WW2 planes that are being discussed here can hit mach 0.64 in level flight anyway, so it wouldn't matter to the E-M diagrams?
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Gripen,
You appear to have misinterpreted those reports, and compounded that by making false assumptions based on your misunderstanding. At the moment you seem to be so far off track with this, and since my explanations don’t appear to be helping, I’m simply ready to give up.
In fact, it seems I can’t post here with out getting sucked into this sort of silliness, so unfortunately, this will be my last post on these boards.
Poke me with a fork… I’m done!
Badboy
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They should rename this game "Nerd Wars". :)
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Originally posted by Badboy
You are welcome.
Looks like Hazed is still gonna shoot me down without augering after though, despite the D9 info :)
Badboy
thnx for chart badboy! superb and just what i needed to see.
and ill 'TRY' not to shoot at you hehe :)
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Hm... I tried to be polite and used easily available sources. Seems that someone can't stand critics. After all these simulations are just games, not real world.
gripen
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It is interesting to note all the posts that say that there is not enough "P" factor "felt" in the AH aircraft. As far as torque induced flight charactaristics, I don't have much to say about it but when AH was in alpha and early beta releases there was a considerable amount of "P" factor in the fm. It was reduced I beleive because of the difficulty even some vets from other sims had with it. I remember the 109G10 and the P-51 being quite a bear to get down the runway straight until I got used to it.
Nothing to add to the discussion, just an observation. :)
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Originally posted by gripen
Hm... I tried to be polite and used easily available sources. Seems that someone can't stand critics. After all these simulations are just games, not real world.
gripen
Hmm... Yes the sources are readily available, and this is just a game not the real world. But from where I'm sitting, the problem has nothing to do with critics, and everything to do with the fact that you have been talking complete and utter nonsense.
Dweeb
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Dweeb,
Well, thanks for support.
While buffet boundary is not same as stall boundary, they might happen at same g load. And this is what happens partially in the case of the P-51; up to mach 0,64 stall boundary and buffet boundary are same as noted in the NACA TN 1719. This conclusion is also supported by another NACA study, NACA Report 1219 (http://naca.larc.nasa.gov/reports/1955/naca-report-1219/), which BTW also explains the difference between stall regime (mach 0,64). Above mach 0,64 buffeting starts before max load factor is reached but because the P-51 reaches it's peak load factor at mach 0,64, it is safe to say that it's buffet boundary can be directly used for instantaneous turn rate comparisons. And from the pilot's viewpoint buffeting warns about coming compressebility effects at speeds above mach 0,64 while doing maneuvers, therefore the buffet boundary is also practical maneuvering limit.
But don't believe me, read yourself and think then again. And if you want more thinking, then study that Clmax issue, link is above.
gripen