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

[Stoney]

In other news, Tropical Storm "Gaston" forms out in the Atlantic...


(Image removed from quote.)


Coincidence or an omen of where this thread is headed?   

Looks like its headed to the Caribbean.  If that's the case, I'll leave now and get the daiquiris on ice...   

[Gaston]

  Error in post: See below 

  


    

[Gaston]

So I took the time to read through Gaston's post and a couple of things seem to have me scratching my head.

 The most striking thing is it seems that Gaston thinks having a high corner speed is a good thing,or am I reading this wrong?
 He then questions Badboy as to why more engine power would make a difference or again am I wrong on this?


 One last thing,I might be wrong again so bare with me but I thought corner speed was defined as the lowest possible speed at which an airframe would pull 6 G's.


     Discuss!                                                                                                   


   

       -No, what I am saying is that ANY downthrottling MAKES NO SENSE IF THE CORNER SPEED IS THAT HIGH....  Which inevitably means that the MOST POWER POSSIBLE to stay as close as possible to Corner Speed is NOT useful for the tightest and fastest possible sustained turns (in nose-tracted aircrafts)... More power simply pulls them into too wide a radius (which does not happen to pushers, for obvious leverage reasons)...

   -My other point is that the predictive power of maths is very poor, as the N1K1 example demontrates.

   I must correct here the speculation on my part that the N1K2's low wing solved the horizontal handling problems: The N1K2 was extensively trained for, and used (successfully) in boom and zoom attacks, which coming from the Japanese indicates to me they STILL didn't think its horizontal handling smelled the roses...

   Also my pilot quotes makes no mention of the N1K2 being any better, which in the context of the boom and zoom training I think could be taken as a clue my speculation about the wing position's positive effect was wrong.

   My overall point is that maths are not at all predictive for detailed, or even rough, comparative performance in WWII fighters: See this Ki-100 vs Ki-84 evaluation as an example:



   "-OK, how about this for substantiated?: "Aeroplane" November 2005, "Ki-100 fighter Database" p. 61-77. (16 full pages on nothing but the Ki-100, with remarkable details, including on the development of the projected high-altitude turbo-charged variant)

Textual quote : P. 76:

"At these schools, the cream of the IJAAF's instructors, all very experienced combat pilots, would give their opinion on the new fighter (Ki-100). Almost all the Akeno instructors were graduates of the 54th Class of the Army Air Academy and also highly-qualified sentai commanders in their own right.

During March and April they would fly the Ki-100 in comparison tests against the most capable Japanese fighter then in service, the Ki-84 "Frank". After extensive testing the conclusion drawn by the Akeno pilots left little to the imagination.

In short, it stated that given equally skilled pilots, the Ki-100 would ALWAYS win a fight with the Ki-84 in any one-to-one combat. They further added that in a combat situation with up to three Ki-84s, the Ki-100 pilot could still develop the battle to his advantage.

The results of the evaluations at the Hitachi school were just as clear-cut. Captain Yasuro Mazaki and captain Toyoshia Komatso,also both graduates of the 54th class, developed the combat evaluation situations for the new fighter, and in order to give an unbiaised opinion of the aircraft, they swapped aircraft after each engagements and attempted combat from the opposite standpoint.

In the first combat the Ki-100 was flown against a single Ki-84 with the Ki-100 winning outright.

Mazaki stated: "When we entered combat with the Ki-100 taking the height advantage, the Ki-100 won every time. Even with an altitude disadvantage the Ki-100 could hold down the Ki-84 in two or three climbs during the exercise"

He added that the Ki-84 was "only superior to the Ki-100 in diving speed. The Ki-100 was much better in the turn and while climbing."


   

   If the math cannot predict that the Ki-100 is worth 2-3 Ki-84s in dogfights, and repeat it after switching pilots, as the Japanese tested themselves, what the HELL can we assume it can predict?!?!?!

   Gaston

[gripen]

Looks like its headed to the Caribbean.  If that's the case, I'll leave now and get the daiquiris on ice...   

It's storming right now here in Finland, is it the Gaston storm?

[RTHolmes]

More power simply pulls them into too wide a radius (which does not happen to pushers, for obvious leverage reasons)

  explain?

[WMLute]

When did we get a Ki-100?

[StokesAk]

When did we get a Ki-100?

I know! He singed up for the wrong flight sim forum.

[hitech]

   If the math cannot predict that the Ki-100 is worth 2-3 Ki-84s in dogfights, and repeat it after switching pilots, as the Japanese tested themselves, what the HELL can we assume it can predict?!?!?!

All is naught, nothing can ever be predicted as gaston just  proved. But doesn't his very proof become invalid since math can not predict anything?

HiTech

[SIK1]

All is naught, nothing can ever be predicted as gaston just  proved. But doesn't his very proof become invalid since math can not predict anything?

HiTech

I always suspected math was useless. From now on instead of using math I will just use what ever I think should be used. You know, what ever I feel like it should be. 

More people need to just go with their gut instinct as opposed to using smoke and mirrors hocus pocus like math. 

[Ack-Ack]

Gaston posted the same drivel over at the Ubisoft forums.  It's also more clear in his posts over at Ubisoft what his motivations are and that is to show how he's made the better sim, his post is rife with "in my sim..." 

http://forums.ubi.com/eve/forums/a/tpc/f/23110283/m/1731089978/p/1


ack-ack

[WMLute]

Gaston posted the same drivel over at the Ubisoft forums.  It's also more clear in his posts over at Ubisoft what his motivations are and that is to show how he's made the better sim, his post is rife with "in my sim..." 

http://forums.ubi.com/eve/forums/a/tpc/f/23110283/m/1731089978/p/1


ack-ack

(quote from Gaston in that thread)

"Which is exactly why you will NEVER find me modelling this thing for my boardgame..."

Board game?

[Baumer]

Hmmm....... this thread seems oddly familiar; but maybe this time the cat will make it.



Of course Gaston can all ways follow the last step and try again in a few months.

[Soulyss]

If the math cannot predict that the Ki-100 is worth 2-3 Ki-84s in dogfights, and repeat it after switching pilots, as the Japanese tested themselves, what the HELL can we assume it can predict?!?!?!

If math cannot be used to predict flight modeling and aircraft behavior then the commercial aviation and the military wouldn't spend thousands of dollars each year on flight simulators to train pilots.  I also think aircraft manufacturers would probably have trouble staying in business if they couldn't use computer models for R&D purposes and prototypes w/out a reasonable degree of fidelity.

[Tupac]

All is naught, nothing can ever be predicted as gaston just  proved. But doesn't his very proof become invalid since math can not predict anything?

HiTech

Its alright HT, Gaston is our "Special Friend" So play nice with him.

[Badboy]

Gaston,

Welcome back, and thank you for submitting your latest theories.

I have given careful consideration to various interpretations of your anecdotal evidence and the extensive theory you have been able to extrapolate from your lengthy analysis. However, it is with some regret that I must inform you of my disagreement with your claim that aircraft with short noses have less power, and that this defeats calculation and the laws of physics.

My argument is that a shorter nose acts like a reduced throttle but without actually reducing the throttle. They both have the same effect of defeating our calculated expectations that do not take into account the basic issue of leverage physics...

It is evident that you have given a great deal of thought to the analysis of this and other anecdotes, and you may be quite certain that those of us who are familiar with your prior work in this field have been loath to come to contradiction with your findings. For example, your hypothesis that throttle setting can influence wing loading:

In effect, my argument is that a Spitfire a FULL power turning at 250 MPH will have a higher REAL-TURN wingloading than a FW-190A at partial power: Lighter wingloading wins, just as everybody says... Note in Johnny Johnson's account the Spitfire pilot says he is at FULL throttle, which explains his defeat in sustained turning...

This was a fascinating example of your work, and I was particularly delighted with your exposition of previously unknown aerodynamic concepts with detailed explanations involving prop disks and barbells.
 

And yes, at full throttle in the turn, the Spitfire will have a higher real-life wingloading than a downthrottled FW-190A... Try different barbell handles and weights and see why...   Gaston

However, I do feel that there were a number of points which might have tipped you off to some potential weakness in your theory:

• The length of an aircraft nose has no influence on throttle setting.
• Modelling calculations really do make accurate predictions.
• Throttle setting and wing loading are unrelated.
• None of this has anything to do with barbells.

Without going into too much detail, let me say that:

• Your explanations appear to be entirely arbitrary.
• They defy the laws of physics.

It is with feelings tinged with melancholy that I must also disagree with your prop disc stress-riser theory as an explanation for the ability of a throttled aircraft to have superior sustained turning ability to one at full power. 

As for the extent of my assertion about the effect of the upper disc half thrust increase relative to the bottom half (which has been described and accepted here by at least one poster), one aspect I think is worth emphasizing is the following: This is equivalent to having the prop's center of thrust move UP, and this upward movement creates a lever, however small: My assertion is that this effect is a heavy burden on the wing load because the propeller blade is at 90° to the fuselage, and this creates an unsupported STRESS-RISER that multiplies the effect that would seem modest otherwise.
I think this effect is of sufficient magnitude to allow a FW-190A to out-sustain turns a Spitfire V if the Spitfire is putting out 1400-1500 HP and the FW-190A is downtthrottled to say 900 hp

Sadly, I must inform you that stress risers are changes in a structure that can cause stress concentrations, and are in no way related to an aircraft's turning ability, and that you have the relationship between power and sustained turning the wrong way around. I am also sorry to pass you the sad news that the single poster you thought had accepted your theory no longer posts on these boards. 

However, more recently, I was particularly interested in hearing you expand on your theory regarding the influence of engine power on corner speed:

no allowance is made here that the "Corner Speed" could be "pushed" even higher with more power (a strong suspicion of mine since the modest METO setting already was already enough to push "Corner Speed" a gigantic 80 MPH above the expected 240 MPH value)...

I am once again reluctant to contradict your hypothesis, because it is clear that you have made a careful analysis of the anecdotal evidence. However, it is with some regret that I must again point out that you have the relationships the wrong way around and you have arrived at a conclusion contrary to the laws of physics. I would also like you to know that during a recent conversation with colleagues, I fought tenaciously for the acceptance of your theories as the subject of a formal research proposal, but was ultimately voted down because despite your use of several very technical and important sounding words, your theories don't really have any aerodynamic merit.

I for one would like to support your obvious and admirable desire to promote what can only be described as very effective aircraft.  Unfortunately, I was unable to conceal the bias in your theories towards the superiority of those aircraft, due to the lack of any real scientific evidence.
 
However, I would like to emphasis that I have enjoyed your detailed explanation of this fascinating theory. While it lacks scientific rigor, it is, nonetheless, yet another riveting example of the great body of work you seem to accumulate here so effortlessly.
 
You should know that I have reserved a special shelf in my office for the theories you have submitted to these boards, and my colleagues and I speculate frequently on what new hypothesis you will extract from the wealth of anecdotal evidence in your possession.

Kind Regards

Badboy