Johnny Johnson, maths and the 1989 Society of Test Pilot report; revisited.

[dtango]

For example a race car slows to corner better and faster  

A fighter does the same you slow up you turn tighter whilst powering into the turn to save from stalling.

It simple logic the faster you are the more wider the turn  at medium speeds you turn better at slow speeds you turn even better but run the risk of staling.

this i believe covers all aircraft. Except when you have one aircraft hats slower than the other i.e a Zero againts a Spit 8 theZero will always turn better due to its top speed being less than the Spit 8. And its weight plays a helping part aswell.

Dear oh dear.  Be careful of using the car analogy for aircraft turn performance.  The analogy breaks down badly and many an aspiring virtual pilot in AH have mangled themselves upon the treacherous shoals of physics believing that the slower you go the better you turn!  

If your airspeed is higher than corner velocity your turn performance will get better as you get slower until you reach corner velocity.  However, the slower you go below corner velocity the worse your turn performance gets!

Why?  Examine the following turn radius equation:



So turn radius is a function of velocity (V).  So hey, the lower V is the smaller the radius right?  Cool!  Slow your airplane down to out turn the other guy then!  Well there's a big problem and that's load-factor (n) is a function of lift which varies with airspeed.  The lower your airspeed, the lower the load-factor (acceleration normal to the flight path) for a fixed lift coefficient.  A decreasing load-factor means an increasing radius by the equation.  Thus there is a maximum turn performance where velocity is at it's lowest while load-factor is at it's highest and that occurs magically at the corner velocity for an airplane.  Slowing down slower than corner velocity means that though you're reducing your airspeed, you're also reducing load-factor which results in an overall worse turn performance compared to at corner speed.

Tango

[B3YT]

i belive the technical term for gastons sciance is "bollocks to the proven facts science"  also know simply as bollocks ,  in some quaters it can be called flights of fancy. seeing as we are taking aboot flight  we could say he has a mixure of the two and there fore has bollocks fancy or a even a flight of bollocks.

[Gaston]

  

Since Gaston  has shown such a lack of understanding,and all people here who completly understand the physics of flight disagree with him, his only recourse is to say you can't use math to prove things (even though with out math you can not prove anything, because the the theory of if a then b and if b then c makes the statement if a then b true, is math) and  by definition to do a proof of anything you must use math logic.

The key difference is knowledgeable  people read articles like this and apply the pilot statements with the knowledge of physics and can understand the why of the situation. And can better see what the pilot is describing.

The spit fire driver saying that he pulled harder to the stage of graying out pretty much shows the why the FW was turning faster. The spitfire driver did not mention wanting to stall at all. So I think it is a reasonable assumption to say the spitfire was traveling very fast most likely above corner speed. Once both planes are faster then their corner speed, turn performance will be determined simply by speed where the slower plane who's is still at or above his cornering speed wins the turn. The spitfires better move would be to simply raise the nose and there by slow to corner speed. Would normally eat the fw for lunch in the turn.

So which makes more since, interpreting the description via a method that does not defy basic physics, or coming up with complete crank theory about how the fw is really a better turner then the spit?

HiTech

  -To begin with the "6G turn at 320" example, I provided the correct answer, but added elements of complexity to your attempts to over-simplify issues in a way that obscures rather than enlighten... I'm not even sure the FW-190A can even reach TRUE 6 Gs at 320 MPH without registering some of those Gs as a steep nose-up deceleration mushing (indistinguishable to a G-meter)... It probably can do it, if barely, and Kurt Tank registering 7 Gs at 400 MPH with MERELY 14 pounds of backward stick pressure demonstrates the aircraft is no longer in a normal mode of flight, or the controls would be heavier than 2 pounds per Gs... No pilot usually mentions overly light high-speed elevators on the FW-190A, but they could become very light, and still remain G-responsive, upon nose-up mushing deceleration...

   In your 6G example, no WWII fighter can maintain 6G AND maintain a 320 MPH speed without diving... So how well they maintain speed at 6 G is clearly relevant to maintaining 6 Gs...

  It does mean that, if we assume inferiority at speed retention at the same 6 G rate of turn at 320 MPH, the FW-190A will either slow down more from 320 MPH, and thus ironically turn tighter, to a slower speed, or it will be forced to spiral down at a steeper angle to maintain 320 mph... (A true disaster in real-life combat, which is why so much real-life WWII fighting is made out of LEVEL turns...)

  Just for fun: Can you tell me WHY spiraling down at a steeper angle than your opponent, to match the turn rate, is a disaster?

   I also think that how you get TO 6 Gs, and if you can increase the Gs fast and carelessly or slow and carefully, is very relevant to real-life combat (maybe you are not concerned with that); On the FW-190A, the build-up has likely better be slower than on the Spitfire...

   As far as ignoring reality, consider this quote from Hitech:

   "The spitfire driver saying that he pulled harder to the stage of graying out pretty much shows the why the FW was turning faster. The spitfire driver did not mention wanting to stall at all. So I think it is a reasonable assumption to say the spitfire was traveling very fast most likely above corner speed. Once both planes are faster then their corner speed, turn performance will be determined simply by speed where the slower plane who's is still at or above his cornering speed wins the turn. The spitfires better move would be to simply raise the nose and there by slow to corner speed. Would normally eat the fw for lunch in the turn."

   -FIRST of all, if he really was that fast, an indication of that would have been the term BLACKING OUT... The fact that he states GRAYING out means he was already incapable of reaching his 6 G Corner Speed...

   So that is the first thing you ignore...

   -SECOND, there was was NO FUTURE HOPE of the turning combat getting better AFTER Corner Speed was reached by turn deceleration, because this simple sentence PROVES Johnny Johnson KNEW he was ALREADY below a speed from which the turn rate changes for the better when you go slower:

   "In another couple of turns he would have me in his sights. ---I asked the Spitfire for all she had in the turn, but the enemy pilot hung behind me like a leech-IT COULD ONLY BE A QUESTION OF TIME..."

   There is NO mention of the extremely steep dive spiral that would have allowed speeds, in the 4-6 G turn range, to remain above the likely 300 MPH + Corner Speed of EITHER aircraft types(!)...

   This is how is described the presumed mythical "spiral" (the only straw you have to cling to for things remaining for significant periods of time above "Corner Speed"):

    "Then we both turned hard left and whirled round on opposite sides of what seemed to be an ever-decreasing circle"

   What SEEMED TO BE an ever-decreasing CIRCLE... OPPOSITE SIDES: No opposite sides in a spiral...

  
   The pilot himself irrefutably contradicts your notion that continuing to slow down would improve things for him: He knew there was no hope of that, and says so as clearly as it can be said...: http://img30.imageshack.us/img30/4716/jjohnsononfw190.jpg
                            

   I think he would be shocked if he saw you thought he could have done better with a Spitfire V: He clearly states only the Spitfire IX redressed the balance, as is well-known... (More power in this case does contradict my notion of downthrottling being a help in turns: Perhaps it is a peculiarity of the Spit, or it was the spiral climb or just plain climbing that made the Mk IX so much more competitive in battle?: Soviet tests show little difference in turn rate with the Mk V at full power, which inclines me to think the Spitfire IX was also better off keeping as high a speed as possible against the FW-190As, just as the Soviets recommended for their own similar-performing domestic fighters...)

  
  
   AND there is a THIRD thing you ignore: He, from the very start of his account -thus making the intended MEANING of the whole thing clear- makes the general but unequivocal statement, a 32 kill ace with the entire war behind him now: "It (FW-190A) also turned better (than the Me-109)"

   He doesn't bother to mention speed, circumstances, or anything else: IT TURNED BETTER, period...

   And THAT is the intended context of his whole story...

   All Gunther Rall ever did is quibble about what he could do with the (900 lbs lighter than G) Me-109F, and even THEN his statement started with: "THEY (Rechlin test facility) told us the FW-190 turned better than our Me-109F"

  

   So if math formulas cannot predict any of this, what is the logical conclusion?

  

   As far as ignoring the irrefutable "proof" of the ability of math formulas to predict performance outcome, can you point to me WHAT features of the Ki-100 allows math formulas to predict it can routinely win a dogfight alone against 3 Ki-84s?

   If you cannot point to a reason why your predictive method WILL predict such an outcome, isn't it the logical conclusion that your predictive method CAN'T predict it?

   One of the basic principles of the scientific method is that the theory (here post-war jet-based math formulas) has to be verified by REPEATABLE experiments. Since we don't test WWII fighters anymore (and the ONE test we have in 1989 showed a 320 MPH Corner Speed, completely at odds with math formulas), then one of the basic principles of the scientific method is not respected:

   You advance a theory but provide no repeated experiments that confirms it.



   In fact, most WWII tests and combat accounts REFUTE the absurd notion that a Me-109G out-turns a FW-190A, as your math formulas so clearly predict... Why don't you look up what the British RAE said when they compared the two?: "P-51B with two full wing drop tanks out-turns the Me-109G but cannot out-turn the FW-190A, even when clean"....


   Besides, insn't it obvious that simplistic math formulas are laced with assumptions that have no real-life validity? After all, math "predictions" failed spectacularly at predicting even the most simplistic of problems imaginable: Can a few pounds of styrofoam, launched at several hundred miles an hour, punch a hole through the wing leading edge of a space shuttle?

   We all know the counter-intuitive answer to that one, don't we? And they had to test it later to confirm even such a simple thing... The finest number-crunchers of NASA could not even predict there was a risk serious enough to be worth LOOKING at the leading edge (I know the whole story about how they half-heartedly tried, and the bureaucratic snafu that prevented it)... Looking at it on TV at the time I wasn't any brighter, mind you, but then I also thought back then the Me-109G out-turned the FW-190A...

   Gaston

    


  

[StokesAk]

Dang, no PNG yet?   

[SIK1]

Where's that dang popcorn smiley.

[dev41]

dtango,

Thank you for your post. While not a math expert (certainly not maths either), your post explained something that had been puzzling me. I was having trouble out turning a 109 K-4 when I was in the 109 F-4. I knew I should be able to out turn him, but he was easily able to cut through my corner. I realize now that I had taken the speeds down way to slow, as I was just above stall speed. I suspect, although I could be wrong (and am willing to be corrected), that flying that low and slow enabled his engine power to pull him through the turn better than I could. Basically I had negated my one big advantage and had turned it over to him. So rather than trying to turn too slowly, I should instead turn at a faster rate and eventually get the inside turn. I do not have film, but does this sound right?

Ubben

[dev41]

...or, as I was thinking through my maths it occurred to me that I could just be a crappy pilot.

Ubben

[BulletVI]

...or, as I was thinking through my maths it occurred to me that I could just be a crappy pilot.

Ubben

Nah  at various speeds the aircraft will turn tighter/ faster you just have to read some performance charts ( google 109 performance sheets and you may be suprised ) or just get a buddy to climb to 40,000 and dive and turn drop hight in a spiral movement and ask him if he's getting a shot on you

[Baumer]

   Besides, insn't it obvious that simplistic math formulas are laced with assumptions that have no real-life validity? After all, math "predictions" failed spectacularly at predicting even the most simplistic of problems imaginable: Can a few pounds of styrofoam, launched at several hundred miles an hour, punch a hole through the wing leading edge of a space shuttle?

Gaston the above quote clearly displays your myopic view of engineering and mathematics as it relates to evaluating system performace. Before you make any more asinine statements about mathematics being unable to predict performance maybe you should read the Columbia accident report.

Here it is for you so you can find it easily, http://www.nasa.gov/columbia/home/CAIB_Vol1.html

In particular here are pages 61 and 62 for you to look at. As you will see in the items I outlined for you in red, there was plenty of data available and software, that had clearly predicted the amount of damage that was caused by the strike.

Be sure to click on the image to see it at full scale.





I seriously doubt any of this information will deter you from your cause, it's clear to me that you're nothing more than a luftwhining zealot who will not listen to reason.

[Dichotomy]

but educational for the rest of us who will listen

[Ack-Ack]

I seriously doubt any of this information will deter you from your cause, it's clear to me that you're nothing more than a luftwhining zealot who will not listen to reason.

Gaston isn't a Luftwhiner, he's trying to prove that he is the better game developer and trying to prove that Aces High has a terrible and inaccurate flight model and HiTech really doesn't know what he's doing.  That is what Gaston is trying to prove, nothing else and he's been failing miserably at it.  Even the guys at the Ubisoft forums think of him in the same light as we do.


ack-ack

[dtango]

dtango,

Thank you for your post. While not a math expert (certainly not maths either), your post explained something that had been puzzling me. I was having trouble out turning a 109 K-4 when I was in the 109 F-4. I knew I should be able to out turn him, but he was easily able to cut through my corner. I realize now that I had taken the speeds down way to slow, as I was just above stall speed. I suspect, although I could be wrong (and am willing to be corrected), that flying that low and slow enabled his engine power to pull him through the turn better than I could. Basically I had negated my one big advantage and had turned it over to him. So rather than trying to turn too slowly, I should instead turn at a faster rate and eventually get the inside turn. I do not have film, but does this sound right?

Ubben

Hi dev41 -

Glad you found the info helpful.  I've been debating how much to answer your question in this thread as well because it's likely to get sucked up in a blackhole with this thread !  

For your specific situation, it's hard to answer for a variety of reasons because when we start comparing relative turn performance it gets even trickier.  You haven't given enough data points that would conclusively validate the cause and effect of your turn performance variation between the 109F-4 and 109K-4.  I suppose this train of thought is relevant to this thread: trying to make performance assessments between aircraft based on anecdotes is very inaccurate because usually we are missing key data that make a big difference.  What people will do (like what Gaston has done) is to make presumptions about those key pieces of missing data which are for the most part are inappropriate which lead to faulty conclusions.

Don't be fooled.  Turn performance can be a tricky topic just evaluating a single airframe.  It gets even more complicated when you want to do relative comparisons between airplanes because a host of other factors get introduced.  When we talk about turn performance we usually try to simplify and choose parameters to constrain and limit the complexity so that key concepts can be understood (e.g. constraining turn performance to a pure sustained level turn at a fixed altitude, fixed engine power output, fixed weight and configuration, etc.).  Turn performance is relative to a lot of factors and that relativity increases when you start comparing dissimilar airplanes.

For your specific situation here are some thoughts for you not knowing key details:

1) Make sure you understand when rate and radius leads to angles advantage.  The smaller radius doesn't always result in an angles advantage!  Would you believe that in a nose-to-tail turn that if one plane has a larger radius but a greater turn rate that the plane with the larger radius will out-turn the plane with the smaller radius but a slower turn rate?  For more details you can read this thread:
http://bbs.hitechcreations.com/smf/index.php/topic,253819.0.html

2) Quick tests for the 109F-4 and 109K-4 (50% fuel, 3k alt, WEP, clean config, best sustained level turn [zero energy gain/loss] ) - back of the napkin testing I got the following:

K4 turn-rate: ~18 dps, best sustained turn velocity: ~175 mph, g-load (calc): 2.7 g's, radius (calc): 826 ft
F4 turn-rate: ~18 dps, best sustained turn velocity: ~160 mph, g-load (calc): 2.5 g's, radius (calc): 747 ft

So the F4 vs the K4, the F4 has an advantage in turn radius but they are both equal in turn rate.  Dropping power or trying to slow down in nose-to-tail (1-circle) turn fight in the F4 would ensure the F4 would lose because best turn rate dictates who has the advantage in that situation.

It should be noted that I achieved those numbers flying to the edge of the envelope in a sustained level turn.  Flying close to the edge but not close enough also makes a significant difference.  For the F4 tests my first runs were at what I thought was the edge but I was only able to achieve a turn rate of 16.4 dps, 2.4 g's, 857 ft radius at 167 mph.  My other runs I was able to push that to data points above but the difference between that and the lower performance was just a hair difference in control input.  The moral of the story, learn how to fly the extreme edge of your airplane which takes lots of practice!

Tango

[Tupac]

Even the guys at the Ubisoft forums think of him in the same light as we do.


ack-ack

I try not to think about Gaston, or you could just be Gaston and not think at all.

[Charge]

Could we still try to keep this at least moderately civil, please? 

In that pre-set situation of Fw vs Spit that if they both would try to maintain their tightest turn of 6Gs what would actually happen IRL?

Presumptions:

In attempt to hold the maximum Gs:
A. FW will need more angles to maintain that G and thus bleeds energy more rapidly.
B. Rather than by having a bigger wing and creating more drag in maneuvers the Spit cannot decelerate as efficiently as FW or risk an accelerated stall, but it will thus keep up high turn rate.
C. In slower speed the more engine power of FW cannot make up for the difference in wing-area and thus, lift as it cannot maintain such AoA that would enable it to compete in turn radius in low speed.


1. FW has higher corner speed and through a 6G turn would hit its best turn rate quicker and seem to gain on Spit initially. As the speed bleeds off the Spit would eventually hit its corner speed and start out turning FW that has now decelerated beyond its corner speed? (In fact Spit would probably start out-turning FW even before Spit hits its best corner speed...)

2. While maintaining its energy better the Spit would actually decelerate slower to its corner speed if it chooses to maintain full throttle?

3. By cutting throttle the Spit can decelerate more rapidly and possibly negate the brief advantage the FW may have in turn radius due to faster deceleration?

The bottom line of this would be that there would be a stage where FW has slight advantage in "turning" to Spit but this advantage is quickly lost (it may not even last a full 360 deg turn!) as the planes decelerate. OR does it, in fact, have even that (Tango?)?!?

If there is a brief advantage existing the best bet for FW would be to make the 6G turn until it hits it best corner speed (270mph?)and maintain that and wait for the Spit to gain angles as it decelerates to its best corner speed (160mph?) and then try to utilize its slightly better E state and better roll rate.

Of course the best option for Spit would be not to choose to decelerate to its best corner speed but just hold speed and by having a better turn rate it will get into FWs 6oc as well but with more E.

I.e, the FW does not really have any real advantage over Spit in turning but the advantage it may briefly have would come through the error in Spit pilots choice of tactics?

-C+

[dtango]

Hi Charge:  

fundamentally the scenario you described is possible for the assumptions you're making, some of which are explicitly stated, while others implicit.  Essentially you're saying that for your scenario the 190 gets to its corner faster than the Spit V which would result in an initial advantage for the 190, which is a perfectly logical conclusion given your assumptions.

In your example you're making some assumptions about things like: a) altitude not being a factor, b) initial starting speeds, c) relative weights not being a factor, d) a given engine output, e) amount of load factor being pulled, etc.  Change any of these and you could get other alternatives as to when and why the FW-190 could out turn a Spitfire....or vice versa.  For instance let’s say that the initial starting airspeeds between the aircraft was even greater with the Spitfire much higher above its corner velocity than the 190, then in your scenario the 190 would have an even longer envelope of initial turn advantage against the Spit.

Like dev41’s virtual example, or Johnny Johnson’s real life anecdote what presumptions we make about key missing information is important about the conclusions we make about performance from a physics standpoint.

Now that I’ve read the full Johnny Johnson article itself I believe there are a couple of clues that I haven’t seen mentioned thus far (though honestly I have no desire to look through the mountains of replies & threads on the topic to check).

1)   Johnson’s story occurs over Dieppe which means the 190 was either an A2 or A3 (assuming it was a 190 and not a 109!).  It’s possible that he encountered a Fw-190A3 with the BMW 801D-2 engine with MW50.
2)   Johnson started at 10,000 ft.  By the time he met the 190 he was probably much lower than that after his initial fight which then resulted in him being alone.
3)   Johnson mentions a head on merge with the 190 and then both making left hand turns which means a nose-to-tail turn fight (two circle fight).  As I mentioned above the turn rate not turn radius dictates the nose-to-tail fight.
4)   Johnson says that as they turned the circles got smaller.  This probably means they were above their respective corner velocities.
5)   Johnson says that he is at full throttle in the turn fight but then later to escape he has to punch in WEP. This means he probably was at military power during the turn fight, but not WEP.

Let’s look using AH climb charts to compare the Spitfire V and the Fw-190A5 which is pretty close to the A3 (more importantly having the same engine).  Notice the rate of climb advantage of the A5 compared to the Spit V below 8,000 ft.  Note the big difference between the Spitfire V MIL vs. the A5’s WEP rate of climb below 4,000 ft.



It’s entirely plausible that Johnny Johnson’s encountered a Fw-190A3 that won the nose-to-tail turn fight against the Spitfire V because of a better sustained turn rate advantage thanks to the 190 being at WEP while Spitfire V was only MIL power.  The 190 could have had a higher turn rate than the Spitfire thanks to the big offset in T/W margin to help it fight induced drag e-bleed.  Of course we’re also missing data about the initial speeds as well as the weights of the aircraft in question.  If the Spitfire was much faster than the 190 and the weights even closer in margin then it would make this scenario even more plausible.

Tango