Author Topic: 190A5 vs 190A8  (Read 64918 times)

Offline Badboy

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Re: 190A5 vs 190A8
« Reply #480 on: April 22, 2010, 03:47:42 PM »
In fact, in the Hanseman case he mentions downthrottling TWICE: Initial downthrottling effect: "He stopped cutting me off"

SECOND downthrottling effect, several on-the-deck 360 AFTER the first one: "I commenced turning inside him as I reduced throttle settings."

So he downthrottled FURTHER, my guess from 250-300 MPH to 225 MPH the first time, then from 225 MPH to 190-200 MPH the second time, while the initially winning Me-109G probably stayed at the same high power throughout the numerous 360°s...

Your first guess may well be correct, because that confirms that he was above corner velocity and reduced throttle for the right reason, but your second guess has him reducing throttle below corner velocity which would not be consistant with improved turning. It is far more likely, that he wasn't doing continuous turns, because if he was he couldn't have moved away from the field. It is far more likely that in his effort to distance himself from the enemy field, he stopped or reduced his  turning for long enough to put some distance between himself and the field, and that he accelerated in the process, which would mean he would need to reduce throttle again once he resumed turning to bring himself back to corner velocity.

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That being said, spiralling down DOES allow much tighter sustained turns,

Nope, spiralling down allows you to maintain speed while achieving a high instantaneous turn rate, but descending is by definition NOT a sustained turn.


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This is why much of WWII sustained turn-fighting is usually as close as possible to the stereotypical sustained flat turns,

The problem with that, as everyone has been trying to explain to you, is that if they were doing flat turns at or below corner speed as you claim, their best sustained turn performance would occur at maximum throttle, and under those conditions reducing throttle doesn't make any sense at all because your turn would be seriously degraded.

We are both trying to interpret those anecdotes, and neither of us can be certain we have it right, but unfortunately your interpretation is not consistant with the laws of physics, and that should be a fairly convincing clue that it might be worth opening your mind to some of the alternatives being suggested that are at least physically possible.

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Offline Ardy123

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Re: 190A5 vs 190A8
« Reply #481 on: April 22, 2010, 03:48:55 PM »
I think I can explain the reducing throttle part.

Often in game, I will reduce throttle and turn hard to force an overshoot. To the other player it looks like a very tight turn, only because they blow past you and sudden find them selfs on the outside of the turn and way in front of you.

try it yourself, grab a 109k4, go about 275 mph and get a spit 16 on your 6. Lower the nose a little, cut throttle, snap roll to the right, and pull back until you almost black out, then snap roll it to the left and pull back again. Most pilots will not cut throttle and will blow past you and you can get the snap shot on the left turn.

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Offline jdbecks

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Re: 190A5 vs 190A8
« Reply #482 on: April 22, 2010, 05:49:23 PM »
I think I can explain the reducing throttle part.

Often in game, I will reduce throttle and turn hard to force an overshoot. To the other player it looks like a very tight turn, only because they blow past you and sudden find them selfs on the outside of the turn and way in front of you.

try it yourself, grab a 109k4, go about 275 mph and get a spit 16 on your 6. Lower the nose a little, cut throttle, snap roll to the right, and pull back until you almost black out, then snap roll it to the left and pull back again. Most pilots will not cut throttle and will blow past you and you can get the snap shot on the left turn.



but it does help to cut throttle in 109 when making right turns as you are fight the torque of the engine
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Offline Ardy123

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Re: 190A5 vs 190A8
« Reply #483 on: April 22, 2010, 07:42:36 PM »
but it does help to cut throttle in 109 when making right turns as you are fight the torque of the engine
Throttle cutting helps on the roll but for a sustained turn I would say no (have not tested), you need the power to drag your plane through the turn without loosing to much e. Late war 109s don't really need to 'out turn' like a zero, they can use their engine to bleed the other guy out of e because they accelerate and climb so well. For a sustained right turn, have a slight nose up, flaps out, full throttle with wep and hold that badboy on as it shakes... the other guy will bleed e and all you need to do then is go up.
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Offline Angus

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Re: 190A5 vs 190A8
« Reply #484 on: April 23, 2010, 04:32:38 PM »
Try a good turn-fight in AH. I normally go for a high-turn rather than cutting throttle, since it will open a way for an upwards escape or give aggressive possibilities.
The only reason to chop throttle is to cut to a quick shot, - after that you are riding the stall, and in trouble if the opponent turns better.
Unless....it is all heading downwards...and in that case, your enemy would have to be lower to allow it...
Either way, NEITHER IS SUSTAINED TURN.
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Offline Ardy123

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Re: 190A5 vs 190A8
« Reply #485 on: April 23, 2010, 04:55:34 PM »
NEITHER IS SUSTAINED TURN.

Agreed, and I tried to elude to that too.

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Offline Gaston

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Re: 190A5 vs 190A8
« Reply #486 on: April 24, 2010, 06:29:47 PM »
  The problem with your collective misunderstanding of how this works is that you ignore, in the specific wording of the accounts, all the numerous clues that these downthrottled turns are indeed SUSTAINED...

  -First of all, there is no mention in any of these accounts of UPTHROTTLING...

  -I concede that downthrottling exists also for cancelling brief overshoots: The short-lived nature of those is very evident in the accounts, and often it can be achieved in other ways, like dropping flaps, side-slipping, rolling violently or, for the P-47, even firing its guns...

  -I do not claim downthrottling below 250 MPH gains a far higher turn RATE: It may or may not according to type, or remain equal on some types. I claim it reduces turn RADIUS greatly. Note Karhila says "I turned equally well, but in a smaller radius".

  -No explanation has been provided by anyone as to why Karhila says the "optimal" sustained turn rate (or sustained turn rate/radius combo) speed of the Me-109G-6 to be around 250 km/h, or 160 MPH(!). This is clearly far below any "Corner Speed" however it is defined. (The Fins tested an unspecified sort of optimal turn speed on the Me-109G-6 as being around 220 MPH, and Il-2 supposedly has it at 240 MPH for sustained turns on the P-51D)

   That he mentions such an extremely low speed in the context of explaining his downthrottling tactics in sustained turns is undeniable... He even mention his tactics in contrast to those who throttled up! He also makes NO mention of upthrottling back up himself, and neither does any of those other sustained downthrottling accounts.

   Note also his wording of the "P-51" dogfight: "I was HANGING behind him, unable to gain deflection, until he made a mistake". Meaning this was going on for quite a while... He described of this specific combat, but in another interview, that the speed of the "P-51" was 300 km/h (200 MPH) in a wider radius, while he was at 250 km/h in a smaller radius, and that the P-51's "higher" speed is what prevented him from gaining deflection: 200 MPH in a P-51 or P-40 is well below even the watered-down 10 seconds to blindness "Corner Speed" of 4-4.5 Gs...

   THAT "P-51" battle, in the other interview, was clearly described as going on for "several" 360° turns near the water... This excludes any "non-sustained" explanations...

   The conclusion I draw from the "P-51" speed being stated as being 200 MPH is that both were downthrottling to their optimal sustained turn rate/radius combination, but maybe because of the 20 mm gondolas the Me-109G-6 barely won despite the wingloading advantage...

   I do accept that the FW-190A is incapable of matching the 160 MPH turn radius of the Me-109G-6, but I do maintain that it has a higher sustained turn rate slightly above that speed (the 109F could compete in rate, but not the G): Say something like the P-51D's preferred sustained turn speeds of 190-200 MPH, but with a better sustained turn rate than the P-51D (because of a smaller radius), and also a better sustained turn rate than most other fighters in Europe except some Russian fighters and some Spitfire Marks.

   I never said downthrottling was advantageous ONLY to the FW-190A, only that it may be MORE so, because of the type's patently awful, and downright scary, high-speed handling behaviour...

   Until the problem of TRACTION/PROPULSION is understood, nothing will be resolved further: In the case of ALL airborne nose-traction, I assert less is indeed more: Here is an interesting example that was presented to me on Il-2 to show me the errors of my ways: It shows a genuine understanding of my argument, but achieves the opposite of what the author intended...

   Here is the argument: If what I say is true for the prop's passive resistance to turning, would it not also mean that the BAC Lightning jet would benefit in turns of lowering the power in its UPPER engine to help the turn? (It is a jet fighter with two large engines in an over-under fuselage position)

   To that I say no... It merely shows how the issue here is so large it cannot be seen: Turning basically means continuously raising the leading edge of the wings (which makes the whole thing very different from climbing): What leverage does the jet engine thrust have to counter-act the raise of the leading edge of the wings? It is the other way around here: It is the wings leading edges that HAVE 15-20 ft. of leverage to deflect the thrust, not the other way around!

   What if we were to modify the BAC Lightning?: Let's imagine re-routing the jet nozzles, say with no loss of thrust efficiency, so that the SAME thrust exits now out of a nozzle on each SIDE of the nose: No longer a top and bottom difference!: The thrust is now 15-20 ft AHEAD of the leading edges (say the median point of them given the sweep), and there is now no vertical separation in the thrust!

   Would reducing the nose pull on such an airccraft, which has NO large flat disc to resist vertical twisting (The side-by-side nozzles have NO right-angle stress-riser vertical leverage like the flat disc prop has), would that produce an increase in sustained turn rate at lower speeds if you lowered the tractive power?

   It would certainly help the wings to keep lifting their leading edges continuously, since the nose-pulling continuously pulls then down!: If they lift their leading edges easier, then it is less taxing for the wing lift to achieve this raising action: Less taxing of the wing lift means less REAL-LIFE wingloading...

   So you can clearly see here the exact same thing remains true regardless of the nature of the traction: The flat prop disc's passive resistance and right-angle stress-riser leverage is only a compounding factor of an inherent nose-traction problem that can be alleviated only by reducing power in a continuous turn (short of putting the thrust at the rear!)...

   All of this would be common knowledge if all jets had their exhausts exiting in the nose... All jet fighter pilots would be today taught to downthrottle in turning combat occurring BELOW Corner Speed if their jets were all nose-tracted... (And that could possibly drive combat speeds down, despite the instantaneous explosive impact of missiles, at least to some extent...) That they might be taught that their principles of fighting was refined in WWII (or even WWI!) may be nice for morale to give them a sense of connection to a glorious past, but it is completely artificial: Nose traction requires you to THINK about turning combat differently...

   It is very nice to repeat like a mantra that "speed is life", but limp-wristed guns when you are going too fast are nowhere near as good as missiles (as the Komet found out), and in WWII it was the limitations of the machines that often forced a type of fighting we seem to have quickly forgotten...

   Gaston

  

  

    

    

  

  
« Last Edit: April 24, 2010, 07:25:17 PM by Gaston »

Offline mtnman

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Re: 190A5 vs 190A8
« Reply #487 on: April 24, 2010, 07:31:53 PM »

News flash!  There's no "prop disc"...

The "disc" is an optical illusion.  It's really just a few small blades moving really fast, that due to "persistence of vision" looks like a disc.  "Looking like" and "behaving like" aren't the same thing. 

Lots of folks see things that look like ghosts and flying saucers every year; that doesn't mean they're actually seeing ghosts and flying saucers.

This "right-angle stress-riser vertical leverage like (you claim) the flat disc prop has" is really limited to just a small fraction of time per revolution of the prop.  It only exists when one of the blades is vertical.  In a two or four-blade prop, that effect would be canceled out by the lower blade moving forward faster (in reality, neither blade is being "pulled back").  In a three-blade scenario, the two lower blades would be countering the effect of the upper blade... 

Any time there isn't a blade pointing directly "up", the effect you argue would be minimized, simply because there's no "right-angle stress-riser".  Anything less than a right angle would be "less", right?  Keeping in mind that we're looking at a full 360 degrees of rotation, there's a blade creating "right-angle stress-riser vertical leverage" exactly what fraction of the time?  Maybe 1/90th of the time (four-blade prop).

You could just as easily present your argument in reverse, by claiming the bottom blade "forces" the nose up, because the up elevator deflection removes some of the obviously much-needed resistance keeping the lower blade from forcing the nose up.  We could even toss in the idea that gravity or centrifugal force are pulling the tail down, or "out" of the turn.  And with all the leverage afforded the tail, due to it's distance from the CoG, surely the tail would prevail.  Besides, in addition to leverage, the tail has brute weight on it's side!  Which weighs more, the blade, or the tail?

Cripes!  It's flat-out amazing that once the elevator is deflected upwards the slightest amount, that we have any hope of stopping or (good-golly!!) reversing that process....  You'd think that once the nose started up (or is the tail dropping???) the effect would be like a runaway train!  The "turn" would rapidly tighten, maybe even flipping the plane around backwards (or maybe just ripping it to shreds?)!  Jumpin' Jiminy!

And who says it needs to be limited to the up/down aspect?  What would the effect be like if the vertical stabilizer was shot off, especially with a three-blade prop?  You'd think that when the blade was straight out to the right, it'd surely overcome the pull of the other two blades, especially since it had the benefit of "right-angle stress-riser vertical leverage" and the other two don't...  It should swing the tail to the right!  And then the left...  Quickly followed by the right...  Like a salmon swimming upstream!

Disclaimer- I'm being a bit sarcastic here...  I was tempted to just mention something about a horse and water, but got carried away...

MtnMan

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Offline Baumer

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Re: 190A5 vs 190A8
« Reply #488 on: April 24, 2010, 07:41:13 PM »
So in essence your argument is, that a front wheel drive car can turn better than a rear wheel drive car since the thrust is forward of the CG.

or, Lets be even more clear, your point is;

I will continue to make aerodynamic conclusions based on second hand information, that is lacking in detail. I will continue to maintain that only MY interpretation of the second hand account is correct, and will denigrate any other proposed explanations.


Here is a fun little experiment, fly a sortie in Aces High (Make sure to record it using Alt-R). Hopefully you can get into a nice little 1 on 1 with someone and win. Now, I want you to wait 1 to 2 hours after the engagement to write as detailed an action report as possible, include items such as initial engagement altitude, initial speed, boggy speed & alt. Then continue to describe the combat, including number and lengths of turns, flap usage (yours and boggys), final altitude. All this without using any cheat sheets and not looking at the film. Then compare the report to the film and tell me what you get.
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Offline FLS

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Re: 190A5 vs 190A8
« Reply #489 on: April 24, 2010, 07:55:35 PM »
I'm pretty sure a right angle stress riser has nothing to do with aerodynamics. Maybe somebody can enlighten me.   :headscratch:

"The problem with your collective misunderstanding of how this works is that you ignore, in the specific wording of the accounts, all the numerous clues..."

I think that's the crux of the biscuit right there.  What we should be doing is reading between the lines and looking at the big picture. We are ignoring the numerous clues that give us relevant information that is not explicitly stated.  :old:

Have a nice day.   :)


Offline Guppy35

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Re: 190A5 vs 190A8
« Reply #490 on: April 24, 2010, 08:10:25 PM »
I'm pretty sure a right angle stress riser has nothing to do with aerodynamics. Maybe somebody can enlighten me.   :headscratch:

"The problem with your collective misunderstanding of how this works is that you ignore, in the specific wording of the accounts, all the numerous clues..."

I think that's the crux of the biscuit right there.  What we should be doing is reading between the lines and looking at the big picture. We are ignoring the numerous clues that give us relevant information that is not explicitly stated.  :old:

Have a nice day.   :)



When did you stop getting old and forgetful FLS and start making sense again? :)
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Offline Gaston

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Re: 190A5 vs 190A8
« Reply #491 on: April 24, 2010, 11:50:30 PM »

  Quote, Baumer: "So in essence your argument is, that a front wheel drive car can turn better than a rear wheel drive car since the thrust is forward of the CG."

  -Everybody in the automotive world knows the handling of front-wheel drive cars is vastly different from rear-wheel drive... Ever saw a rear-wheel drive car make a hairpin turn in a Rally? See what happens next when a front-wheel drive car makes the same turn...

  Quote, mntman: "News flash!  There's no "prop disc"...

  The "disc" is an optical illusion."

   -Yes I know: You can actually prove that by putting your hand into it real quick! Try it!

   Gaston

   P.S. Wasn't the crux of my argument that the thrust location at the nose mattered more than whether it was a prop or not? I think some posters here didn't quite read or understand all of it...

   G.

   

Offline WMLute

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Re: 190A5 vs 190A8
« Reply #492 on: April 25, 2010, 07:45:21 AM »
Ever saw a rear-wheel drive car make a hairpin turn in a Rally? See what happens next when a front-wheel drive car makes the same turn...

Some of the all time best Rally cars have been RWD.

Ferrari 288 GTO
Ford Escort
Opel Ascona
Opel Manta
Talbot Sunbeam Lotus
Vauxhall Chevette
Toyota Celica
Porsche 911
Fiat 131 Abarth
Opel Kadett
Lancia Stratos
Ford Fiesta
Triumph TR7
Ford Fiesta
Peugeot 205
Darrian T90
Hilman Impian
Hillman Avenger
Renault 5
Toyota Starlet
Toyota Corolla AE 86
Ford Sierra RS
Lancia 037
BMW 325i
Vauxhall Magnum

Not sure what you are getting at here...

Before most went to AWD some of the top Rally cars were RWD.

If you are saying FWD is a better handling car than RWD then I think the nice people at Ferrari, Porsche, Lamborghini, Mercedes Benz, McLaren, Shelby SuperCars, BMW, Saleen, Jaguar, Koenigsegg, Audi (etc, etc) might have a thing or two to say about that.
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Offline Scherf

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Re: 190A5 vs 190A8
« Reply #493 on: April 25, 2010, 08:15:05 AM »
Are you seriously trying to tell me that broccoli is better than sprouts?
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Offline hitech

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Re: 190A5 vs 190A8
« Reply #494 on: April 25, 2010, 08:46:34 AM »
Gaston please learn to use correct terms.

1. the word optimal, simply means best. You are mixing 2 concepts.

2.  You say "optimal turn speed", and ("optimal"  sustained turn rate). They are completely different concepts. The key concept being the word SUSTAINED.

Every one here has given you the definition and why 160 is the best sustained turn rate. and 220 being the best turn rate , the key being able to hold the same speed and alt are the different between the concepts.

So the official terms would be best sustained turn rate. And best turn rate.I.E.  Best turn rate & radius happen at corner speed. Best SUSTAINED turn rate & radius happen close to best climb speeds. Corner speed in AH (limited at 6 g's) happens at 2.44 * Stall speed. Corner speed happens at the sqrt(glimit) * Stall Speed.

now many people will leave out the word "Optimal or best" when speaking of sustained turn rates, it is automatically assume the word best or optimal is applied to the sentence or people would stat it more like what rate of climb or turn can be sustained in at 220 mph. But this is not the same concept of best sustained turn rate. It is the same concept when some one states the max speed of a plane, they are leaving out the part that it will only do this speed at one altitude.

If you were to try SUSTAIN a turn at 220 mph (this means not slowing down and not descending) you turn rate would be at least half of what your SUSTAINED turn rate would be sustained at 160 mph. And this is where you are constantly mixing terms. It is conceivable you could get a better turn rate and radius with reduced throttle at corner speed ( sorry I have not crunched the numbers to find out) but this will be at the expense of loosing altitude more quickly, notice we are not using the word SUSTAINED because this is not a sustained turn, we are loosing alt, and there fore will very quickly have to stop the turn, or hit the ground. Hence why the word SUSTAINED is used.


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-No explanation has been provided by anyone as to why Karhila says the "optimal" sustained turn rate (or sustained turn rate/radius combo) speed of the Me-109G-6 to be around 250 km/h, or 160 MPH(!). This is clearly far below any "Corner Speed" however it is defined. (The Fins tested an unspecified sort of optimal turn speed on the Me-109G-6 as being around 220 MPH, and Il-2 supposedly has it at 240 MPH for sustained turns on the P-51D)

Now as far as you disk loading, could you please draw a simple sketch of this loading you are referring to? If you would I can fairly quickly do the math for you to show you it's net effect with full power and reduced power.


Gaston , it is obvious to me you are truly interested in these topics. I and a few others here know the physics side of this very well, and contrary to your belief, planes do not fly out side of the realm of physics. (If you do not except this concept of physics are true, your hole riser argument also falls apart, because you are trying to make a physics argument as to why the effect is there) If your "Disk riser concepts" is true, then your sketch would very quickly prove it to be true once we crunch some numbers.

HiTech