190A5 vs 190A8

[Angus]

I have heard a pretty good tale where a P51 out-turned a 190 on the deck with one notch of flaps. It would seem real to me. The same pilot however once almost lost a turnfight with a 190, - this time he flew a Sptitfire MkV. "Almost lost" means that he decided to end the turning and disengage (he used controlled a snap-stall (spin entry) to reverse the turn and disappear under the nose of the 190) and get away). But my guess is that the 190 was already happy to get out of the lock, probably absolutely close to stalling. This would have been a 190A5 or even less,- it was in the summer/autumn of 1942.
It was the only time when he was seriously worried in a turnfight with a LW fighter, - he claimed the 190 being a much more feared opponent than the 109, - in the beginning. Later on, he had no problems with it, - there was even an engagement where P51's chased higher 190's UPHILL and caught them at 20K!!!!! (from 12 to 20K)
Anecdotes are anecdotes, but a combat report is but the same, only done and written from an encounter happening very shortly before, and perhaps putting more accounts into an assumption.....

[Gaston]

   -Yes, the FW-190A will be out-turned even at slow speeds if the pilot keeps more power on than the P-51... Also the FW-190A had a fearsome stall, especially at higher speeds, that needed a deft touch to catch it, and it seemed to intimidate a lot of pilots who were described by American pilots as being afraid to "reef it in" at low altitudes... I look at it this way: It took me twelve years of study to finally ignore the wingloading data... I'll bet many of them didn't believe it either: I know for a fact Walther Oseau was one of them, and one of his fellow officers attributed his loss to his scepticism about the FW-190A's turning ability (I can source this)... He had to spiral his Me-109G-6AS down 20 000 ft. because "His aircraft slowed down in tight turns, more so than his P-51D adversaries...". This according to a witness...


   -I know of this particular P-38 account and it is to me a significant one, as it was well-detailed, and whatever variables may be at play, with many other examples it tells me that at the very least the Me-109G did not out-turn the P-38 at some speeds, but that the reverse was likely true... My conclusions about the relative vertical and horizontal merits of the Me-109G and FW-190A took thousands of accounts to sift through before a clear picture finally overcame my decades-long prejudice, and I realized that boom and zoom FW-190As were largely a myth, as were routinely tight-turning Me-109Gs...

    I present only a few of the more clear accounts, but there are thousands of others seen over decades that also formed my opinion, including all the P-47/P-51 accounts of the Mike Williams "WWII aircraft performance site"... About 1200 of them right there...






  Quote, Badboy:

   "What this means is that in this case, a pilot entering a fight at some speed significantly above 225mph and who wanted to perform a maximum rate turn within his physiological G limits, might choose to do it by reducing throttle until his speed was between 212 and 225 mph. Remember, if he can only pull 4.5G for about ten seconds before losing his vision, any time he spends flying faster than his 4.5G corner velocity will be time spent turning at less than optimum conditions, and that means allowing an adversary to gain on him in the turn. So it is hardly suprising that there are anecdotes describing just that. However, once they reach their 4G or 4.5G corner velocity (depending on the particular pilots G tolerance) their best option would be to try to maintain that optimum turn for as long as possible. That means going to full power! But even at full power, they couldn't maintain that turn, they would need to exchange altitude for it by entering a descending spiral turn with an angle of descent of between 5 and 8 degrees, so a relatively shallow descent.  You can see from the EM diagram that staying level and allowing the aircraft to decelerate to its best sustained turn may not have been the preferred option. Firstly because the best sustained turn rate is about 20dps but it can achieve 23dps and 24.5dps at the 4G and 4.5G limits respectively, and when you consider that a 2dps advantage was considered decisive, that extra turn rate is very significant."

   -This is very interesting, and by lowering the G "Corner Speed" limit to the "10 second vision loss limit" you do get a lower Corner Speed that appears more in line with what is going on in the accounts we have... However, two things clearly don't agree with the accounts:

   -The downthrottling you described would be very fleeting, as even by just doing a hard flat 6 G turn WITHOUT downthrottling you would easily lose 50-70 MPH or more in a single 360° turn, and you would achieve that without having to fiddle with the tricky and worrisome procedure of reducing the throttle and THEN having to throttle back up...

    Granted, the FW-190A had a "brainbox" throttle that made this easy, but the FW-190A pilot who mentionned downthrottling in this forum said he did so BEFORE the merge with P-51Ds even occurred... Downthrottling was part of preparing for combat from CRUISING speed... Slow turning from the start was his combat speed all the way through most of what the enemy did, except diving perhaps... You can bet any other WWII type that has a pilot wanting to fiddle with the throttle to lose speed in a fleeting manner would do it for the urgent need to not overshoot a vulnerable target about to be hit: It is indeed a very short downthrottling, as it is the equivalent of hitting the brakes before a corner (P-47s even sometimes fired their guns for this purpose!)... You hit the brakes in a corner, but not all the way around the racetrack...

    Yes a brief slowdown was often made to allow not overshooting or turning briefly tighter... But downthrottling is not always the easiest way to do this, and all the examples we discussed are clearly multiple sustained 360°s with NO mention of throttling back UP in ANY of those...

    The fact is, unless you are just out of a very serious dive, you lose speed badly enough in a sustained turn to not have to worry about changing your throttle settings TWICE during turning combat...

     It is very clear in those previous accounts (including Karhila's multiple sustained turns, on-the-deck, with a "Mustang"), that downthrottling involved NO throttling back up, or why would Hanseman say: "The AA fired on me EVERY TIME I got close to the airdrome" "I worked him GRADUALLY away from the airfield" and, AFTER all of that, best of all: "I commenced turning inside him as I decreased throttle settings" (This after being initially out-turned by the Me-109G when speeds and his throttle were higher...)

    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°s 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...

    Conspicuous by its absence is any mention of UPTHROTTLING, despite the proximity of the ground... So the weight of evidence is clearly 2:0 in my favour in this specific example...

    Some of the Japanese pilots of course knew about it, and a hilarious account illustrates this well: 12-16 late P-38s were attacking from all angles a lone low-flying Ki-43 Oscar, all trying to shoot it down, taking turns at different tactics for about half an hour... All ran out of either ammo or fuel and had to leave the scene, not having scored a single hit... Said one of the P-38 pilots: "He seemed throughout the ordeal to be loafing about at reduced power with his canopy open, always turning with the needed angle to spoil our attacks..."

   -The last italized phrase in the Badboy quote has a very important point I want to make: Spiralling down to maintain 4-4.5 G is NOT what a WWII combat pilot wants to do when "locked" in a sustained turnfight (and yes, real slow-speed turnfights DO lock you INTO them at lower speeds when the aircraft is not so able to "flick out"...); Spiraling down when chased is a clear sign of weakness, meaning you can't keep your adversary away from your tail and maintaint the all-important altitude advantage or even height parity. Spiraling down is NOT what a WWII pilot would choose to do from a tailing enemy as it is the same thing as surrendering the high ground: They could not care less about minute optimum turn rate changes since losing the height while turning and being tailed means they will almost surely lose, in the "real" world...

    That being said, spiralling down DOES allow much tighter sustained turns, but not only for the obvious reasons; Because for once speed is increased while REDUCING the all-important prop disc load... But in sustained turns it is the way out for the inferior-turning aircraft, and often no way out at all in the long run, because you cannot really raise your nose to shoot above yourself in maximum-rate sustained turns, especially when nose-down... Out-turning if you are in front in this case will get you little but to lose more altitude than the opponent...

    This is why much of WWII sustained turn-fighting is usually as close as possible to the stereotypical sustained flat turns, unless the chased aircraft is significantly inferior in flat sustained turn performance at the speed it is occurring, in which case it HAS to split-S, climb or spiral down.

     Gaston

  

    

[PJ_Godzilla]

   Downthrottling was part of preparing for combat from CRUISING speed... Slow turning from the start was his combat speed all the way through most of what the enemy did, except diving perhaps...

You hit the brakes in a corner, but not all the way around the racetrack...

Said one of the P-38 pilots: "He seemed throughout the ordeal to be loafing about at reduced power with his canopy open, always turning with the needed angle to spoil our attacks..."
    

Regarding the top excerpt, consider the following:

1. your assertion about the disk loading states that the effect of the reaction torque reduction caused by downthrotting is immediate. I accept this argument, though not your scaling argument (see HT's estimate and my own response to his estimate in which I, in turn, estimate the relative velocity and alpha change on the blades due to turning). Why, then, would F-dub pilots feel any need to downthrottle prior (better answer: to get to something like the right speed for max dps/min radius -which would involve a delay, turn onset, then upthrottling to overcome the increase in induced drag) to combat? Further, if the practice of reducing power to improve turn rad and rate were used on 190s, why would it not also make sense to use the same effect on other aircraft - all of which would experience the same effect? Yet, it is not tactical practice to do so on any other notable type... Were the pilots of all other types presumably unaware of the effect?

No, your account doesn't sufficiently explain why the F-dub would be the only type to be flown this way. Badboy's explanation, otoh, is far more plausible.

2. At the same time, I find it entirely possible that wanting to go into the fight at something more like corner might make more sense for the pilot than entering the turn at a higher speed and allowing decel. Why? Because prior to decel and at pilot limit, your dps and rad are both worse than at corner - i.e., for the same g load, at the higher speed your turn is larger (again, g=v^2/r). I'm also curious, at this point, about the relative acceleration performance of the FW as compared to, e.g., a Spit VIII or IX. If the Spitter holds E better (and I think it does), the F-dub might, by getting to corner prior to fight start, have a brief turn advantage over the Spitter. Consider, for example, a Spit that can make a 4g pilot limit at a lower speed than the F-dub... if it's currently at 325mph and the F-dub is already at corner, who has the turn advantage? - given that the pilot limits are similar, the answer is something like a 9/4 ratio in favor of the a/c at corner). I'd also cautiously here assert, if indeed th e Spit is worse at accel/decel that inducing an overshoot or "too-large" energy scrub from a Spit-flying foe might be a decent tactical idea for the F-dub jockey.

3. Regarding the Ki43 and P-38s, I have little doubt that a good Ki pilot could make decent evasives of attacking high-speed 38's from a reduced power setting. This says nothing objective about the impact of power available on sustained turn rate.

4. Combat Flaps: we don't have 'em on the F-dub in AH but you could expect their effect to reduce your corner speed and increase your best turn rate/decrease turn r.

For a decent development of this, I might point you to BadBoy's fairly neat ACM guide (kudos on this, BB): http://www.netaces.org/badboy/Acmi.pdf

So, I see little reason that popping flaps is something too difficult to understand IF we accept that the FW pilots were behaving as posited above in 2..

5. You DON'T hit the brakes in a corner (unless you want to spin). The cardinal rule of racing is "throttle in a corner, brake in a straight line". This simple statement betrays a misunderstanding of the weight transfer impact on traction in an auto  AND a misunderstanding of the fact that more power is required, both in flight and in an auto, to overcome, in the case of the ac, greater induced drag caused by "uplifting" or, in the case of the auto, the greater rolling resistance caused by maintaining a slip angle to generate cornering force.

In short, I think the FW argument you posit, while interesting, is caught in a logical trap (i.e., why is the practice limited to this type? your explanation is insufficient), a theoretical trap - see any decent development of the turn performance min radius equation, and an empirical trap - see test data on just about any type of aircraft for which turn performance data is available.

Anyway, that's my read on this thing.

[Delirium]

I post my favorite 38 combat report all the time and it involves a 38J pilot still carrying his 500 pounders, out turning a 109G in a fight on the deck after being bounced by the higher 109.  If that's my evidence then I can claim that a P38J carrying 500 pounders should out turn a 109 every time. 

I think everyone has tried talking sense into them, without success.

If you ever want to chuckle, read the interviews the Allies had with the Luftwaffe after the war ended.

[TequilaChaser]

That being said, spiralling down DOES allow much tighter sustained turns, but not only for the obvious reasons; Because for once speed is increased while REDUCING the all-important prop disc load... But in sustained turns it is the way out for the inferior-turning aircraft, and often no way out at all in the long run, because you cannot really raise your nose to shoot above yourself in maximum-rate sustained turns, especially when nose-down... Out-turning if you are in front in this case will get you little but to lose more altitude than the opponent...

* It is nowhere near a sustained turn if you are not keeping the same altitude yet are losing it......

* your nose would not be be down / below the horizon in a maximum sustained turn, and yes you could seriously be able to raise your nose to shoot   if you needed to, although in reality one would be more inclined to shoot level or even lower their nose to shoot ( unless the opponent went to climb - think YoYo )

your definition and theorys of Maximum sustained turns are completely off base, and for one to raise their nose in a maximum sustained turn would only lower their turn radius, only making the "maximum sustained turn" less in regards of "maximum sustained TURN RATE", they would infact have a smaller radius when raising the nose.....the Turnrate would suffer......

Not sure where you going with the Shaw's Book, and saying that Jet Propulsion and Prop Driven AirCraft are the same....... got a page # to throw out to us bottom feeders, so we can see exactly what you are talking about......

Note - as it relates to INGAME- in Aces High, when (2) opponents go toward one another and merge, you could say it is a 50/50 crap shoot that one if not both will sometimes attempt to "Reduce Throttle" to gain angles  ( read as better TURN RATE" on the initial merge....... however WRONG that maybe........ is left to one's own interpetation...

just saying......

oh, and Prop Driven Aircraft produce their most POWER / Thrust right at / near Stall Speed at WOT..... to where as A Jet Engine / Aircraft produces its Thrust well on upstream of that somewhere like  near Corner Speed Area of its pfight envelope.... ( not counting AFB )

[hitech]

TequilaChaser Wrote

POWER / Thrust wrote POWER / Thrust is best at Climb Rate On prop plane.

While your concept is correct,(Thrust goes down) Power dosn't change a lot from climb speed to top speed on most wwii planes/constant speed props. And in some cases power can increase with speed do to ram air effects and exhaust thrust.

HiTech

[hitech]

(Image removed from quote.)
Wit words you speak, and tone you set, ya shall be forewarned, I sense a PNG in someones future....

Ardy, nothing Gaston has wrote is in any way out of line with this bbs. His conclusions are very inaccurate, but he has done nothing but argue his ideas which is always legitimate.

HiTech

[PJ_Godzilla]

Ardy, nothing Gaston has wrote is in any way out of line with this bbs. His conclusions are very inaccurate, but he has done nothing but argue his ideas which is always legitimate.

HiTech

Hear, hear... That's a spirit of transparency and open debate that at least one more Chief Exec. would be wise to emulate. For without it, credibility suffers...

[TequilaChaser]

While your concept is correct,(Thrust goes down) Power dosn't change a lot from climb speed to top speed on most wwii planes/constant speed props. And in some cases power can increase with speed do to ram air effects and exhaust thrust.

HiTech

Yes Sir, I understand your concept, however I did not write what you quoted me on exactly like that

:

hitech posted the following:
TequilaChaser Wrote

Quote
POWER / Thrust wrote POWER / Thrust is best at Climb Rate On prop plane.

I do understand the differences in the thrust & overall power relations, I need to think about it to get my head around the "exhaust thrust" effect for prop driven engines ( turbo Props I could relate to this ), I know this to be so for Jet engines, I am not seeing it for the prop driven engines, outside of a little added side effect perhaps....

my apologies if I did not go into detail enough in my 1st reply.

edit: I am not arguing or debating the fact  ither 

[Angus]

I am still trying to understand how anyone could think that chopping throttle would increase ROT, - or ROC......
Try chopping throttle in the best possible climb...and only ONE thing will happen ... to begin with....

[hitech]

Yes Sir, I understand your concept, however I did not write what you quoted me on exactly like that

:
I do understand the differences in the thrust & overall power relations, I need to think about it to get my head around the "exhaust thrust" effect for prop driven engines ( turbo Props I could relate to this ), I know this to be so for Jet engines, I am not seeing it for the prop driven engines, outside of a little added side effect perhaps....

my apologies if I did not go into detail enough in my 1st reply.

edit: I am not arguing or debating the fact  ither 

at 375mph 1 lb thrust = 1hp.

Exhaust thrust could be as much as 100 lbs. (simply put the engines exhaust nozzles face backwards creating thrust). So at 375 on a 1000hp engine you would be adding 10% HP.
But at 187 MPH you would be only adding 5% HP.

Check out the mosquito speed change with and without flame dampers do to exhaust thrust change, I believe it is about 17MPH top speed.


HiTech

[Baumer]

From the 190 engine performance thread, if you look at the bottom of this chart you'll see the thrust generated by exhaust at 2400 and 2700 RPM.

[Mister Fork]

Wow Baumer. Excellent work.  Your reworking of that equation was well nothing short of just ‘brilliant!’.

[sidebar]
For the aerospace educationally challenged, or for those who should read themselves a book on it, I had book while I was a gilder pilot as a cadet over 20 years ago.  Got the old version from my friend’s dad who was an American Vietnam Phantom pilot.  I lost it after a military posting in 1995, but I just found another new version of it on-line.  


For most flight schools, this book is a must-own.

Google has a preview of it  HERE

Amazon also has it for around $17.

I’m not an expert like Baumer on this – but I do understand the complex and underlying principles of centrifugal forces,  weight and gravity, aerodynamics, drag coefficients, lift, propeller design, stability and design, wing load, moment arm, parasite drag, induced drag, thrust and the relationship between engine torque and horsepower and how it accelerates an aircraft, surface tension, and the oh… hundred of other factors that impact how an aircraft moves in the sky.  Throw in air temperature, humidity, and the physics of air itself, it’s not an easy science.  

Chapter 3 of the FAA book has everything you need to know the basics.  It’s written for someone who wants to know more about aircraft, and you don’t need a PHD to understand the language.  If you can fly the Spitfire I in Aces High, you’re already half-way there.
[/sidebar]

[Baumer]

I can't claim credit for the formula reduction. It's from Wikipedia's wing loading page, scroll down to effects on turning performance.

http://en.wikipedia.org/wiki/Wing_loading

I think it's great that you posted about the Encyclopedia of Aeronautical Knowledge. Getting more people to understand the fundamentals will help make these kinds of discussions more meaningful. Terms like instantaneous turn, sustained turn speed, and sustained turn rate, have very specific definitions and are often times used incorrectly.

Here is a link to a free copy (in .pdf) from the FAA of the handbook of Aeronautical Knowledge.

http://www.faa.gov/library/manuals/aviation/pilot_handbook/

 
 

[Badboy]

  -I love the part about ANY aircrafts... Props and jets are exactly the same folks: Remember that... It kind of reminds me of my gape-mouthed reading of Shaw's fighter tactics book, which showed not the slightest glimmer of understanding of the difference between TRACTION and PROPULSION: You have to wonder why engineers even bother using those terms... Most of the WWII anecdotal examples he produced unsurprisingly involved the P-47, which is probably the most likely prop aircraft to produce accounts flattering to his near-total lack of practical understanding of actual WWII air fighting (shared by a lot of US Navy test pilots apparently)...

It is a fact that reducing throttle in any aircraft will reduce its sustained turning performance, it doesn't matter if it is a prop or a jet. So if both Shaw and I don't have "the slightest glimmer of understanding", how is that we both understand that very simple concept and you don't?

Your argument basically amounts to, I put a bigger number into an equation, and therefore a bigger outcome is necessary in real-life as it is in the equation... Has it occurred to you that turning inefficiency can drastically increase with more power? And that several different aces from several nations have mentionned downthrottling as an essential part of dogfighting?

Of course, but reducing throttle will only improve turning if the aircraft is far enough above corner velocity to warrent it, but it won't ever improve sustained turning performance, that just isn't possible.
 

http://www.virtualpilots.fi/feature/articles/109myths/#g6r6

Let's see an interpretation of this...

Certainly, you can interpret the quote below without breaking the laws of physics as follows: 

"I learned to fly with the "Cannon-Mersu" (MT-461). I found that when fighter pilots got in a battle, they usually applied full power and then began to turn. In the same situation I used to decrease power, and with lower speed was able to turn equally well. I shot down at least one Mustang (on 4th July 1944) in turning fight. I was hanging behind one, but I could not get enough deflection. Then the pilot made an error: he pulled too much, and stalling, had to loosen his turn. That gave me the chance of getting deflection and shooting him down. It was not impossible to dogfight flying a three-cannon Messerschmitt."

In the first three sentences of that quote this pilot claims that decreasing power enabled him to turn "equally well" but there is no indication what speeds, and in fact he must have been referring to speeds above corner velocity, because that's the only way his statement can be true. He was also not out turning the enemy aircraft at that point because when he says "I could not get enough deflection" that means he was stuck in lag. If we assume that both aircraft were at relatively high speed, that would mean that when he referrs to the enemy pilot stalling, it would have been an accelerated stall. Just because a stall was mentioned, doesn't mean they were flying slowly, and the next quote confirms this:

"When the enemy decreased power, I used to throttle back even more. In a high speed the turning radius is wider, using less speed I was able to out-turn him having a shorter turning radius. Then you got the deflection, unless the adversary did not spot me in time and for example banked below me. 250kmh seemed to be the optimal speed."

Here he clearly states that the radius is wider at "high speed", and that his advantage came from having a shorter turning radius. The point is that you only get a shorter radius if you reduce speed when you are already above corner velocity. Once you are at or below corner velocity reducing speed won't reduce the radius any further. So this quote clinches it, and this pilot clearly understands the relationship between speed, power, and turn radius, and that decreased power only works to improve the turn radius when you are above corner velocity.

The problem is, that you are saying that this works at speeds below corner velocity and that reducing throttle improves sustained turning, both of which are wrong. Below corner velocity the turn radius remains almost constant, and in order to achieve a better sustained turn you must increase power, not reduce it.

What you are suggesting isn't just wrong it is impossible, and the process of sound reasoning required to interpret those anecdotes, involves eliminating the impossible, not embracing it as you are doing.

Badboy