Spit IIa

[Crumpp]

"therefore failed to meet the accepted requirements"

Ok - I admit I shortened "failing to meet acceptable requirements" to just "unacceptable."

Was I wrong?

you don't come away with the impression that the Spitfire was a POS from a handling point of view.

Nobody said it was a POS. There are some very good qualities the Longitudinal Instability gave the aircraft from a flying perspective. I love the Spitfire.

It was a two fingered aircraft and one can see how its pilots felt all you had to do was "think about it" and the plane responded. It is an airplane a highly skilled pilot would have love to fight in.

In rough air, Instrument conditions, as a gun platform, precision landing or precision aerobatic platform, the early marques could best be described as skittish. It certainly was not ideal for those missions and a more stable aircraft would not require as high a degree of skill to perform the same maneuvers.

In terms of your game, the excellent stall warning the type possessed means that any computer FM based on 2D Clmax calculated turn performance is optimistic.

They also said with respect to being able to rapidly pull to Clmax without the risk of stalling:

No they don't say CLmax, they say maximum lift coefficient and they list those coefficients achieved in the report. That makes it very easy for somebody who wants to program a computer game, btw.

That is the source of the confusion between the NACA and the RAE. Somebody at the RAE thought it was 2D Clmax too.

Something most Fighter pilots would consider a highly desirable characteristic.

Again, a skilled pilot would love it. He could pull very quickly to the burble and back off to the point just before to achieve that maximum lift coefficient to make his best rate of turn. All within ~3/4 of an inch of stick travel.

NACA's referenced requirements ... nobody else's

The United States had the ONLY stability and control standards during the war on the Allied side.

Only Germany and Japan had stability and control standards at the beginning of the war. The NACA was the first Allied organization to develop any standards. The British never did during the war and it was not until post-war that they came on board to develop any.

Remember, a stable airplane can do any maneuver an unstable aircraft can. The stable airplane can do it just as fast and more precisely requiring a less skilled pilot to do the same thing. It can also do things the unstable one cannot. Such as not destroy itself by overloading the airframe, shoot down other airplanes much faster, land with more control and precision, maneuver better in rough air, and hold a precise altitude/heading in instrument conditions.

[Crumpp]

It is amusing insight to human perception that some of the pilots were not happy when the RAE did address the Longitudinal Instability of the early marques. Some pilots actually felt the bob weights took away the maneuverability.

All they did was increase the stick force gradient to make the longitudinal control heavier. Bob weights do not effect the dynamic pressure acting on the control surface or even the hinge coefficients.

Bob weight force is simply added to the force gradient already present to achieve a higher stick force per G resulting in the perceived stick forces achieving the minimum standards.

[Crumpp]

Thanks

You are welcome!

[Crumpp]

The premise of the discussion was NOT flying in Hard Buffet at all ! but on the very first indication i.e. The "Buzz" or the "Nibble" or the "Burble" ... what ever you want to call it.

Why do you think I disagree with you?

Yes the correct technique to achieve maximum rate of turn performance without FBW is to fly to the first indication of flow separation and back off to the point just before that flow detaches.

Tell me this, does CoD model the effects of the stick shaker zone or does maximum rate of turn performance occur at 2D CLmax?

[CaptainDoggles]

Originally Posted by Crumpp

Yes the correct technique to achieve maximum rate of turn performance without FBW is to fly to the first indication of flow separation and back off to the point just before that flow detaches.

I imagine this is what the RAF pilots were taught, however I could easily see less-educated pilots or perhaps pilots who didn't grasp (or weren't taught) the physics misinterpreting as "fly in the buffet zone".

Tell me this, does CoD model the effects of the stick shaker zone or does maximum rate of turn performance occur at 2D CLmax?

We haven't done a lot of testing yet as our flight models are still somewhat out of whack (see flamefests re: Spit Mk 2) and are due to be changed in the next patch.

If I were to hazard a guess it would be that buffeting does not decrease the turn rate, and is merely a cosmetic effect applied to the player's screen/speakers to warn of impending accelerated stalls.

[RAF74_Winger]

Originally Posted by Crumpp

53lbs would be considered the minimum control force the pilot should experience at a 6G acceleration.

Originally Posted by Crumpp

7500lbs/140 = 53lbs

Selective reading, again. The linked document actually states this: (2) For stick controls, W/140 (where W is the maximum weight) or 15 pounds, whichever is greater, except that it need not be greater than 35 pounds.

The spit Mk1 MTOW is 5,844 lb BTW, gives me 42 lbs according to the FAA formula for chimp-proof civil aircraft.

Originally Posted by Crumpp

IIRC, in the case of the NACA test, the stick force at CLmax was ~22lbs.

At what speed? What was the resulting acceleration? You're only telling half the story.

W.

[RAF74_Winger]

Originally Posted by crumpp

no they don't say clmax, they say maximum lift coefficient

?

W.

[JtD]

Naca Spitfire reports are available here.

[TomcatViP]

Originally Posted by jtd

naca spitfire reports are available here.

thx !!

[Crumpp]

Selective reading, again. The linked document actually states this: (2) For stick controls, W/140 (where W is the maximum weight) or 15 pounds, whichever is greater, except that it need not be greater than 35 pounds.

To be airworthy......

That is not the ideal by any means nor did the Spitfire have unacceptable stick force gradients.

It had a low stick force gradient and that served to aggravated the neutral longitudinal stability issue.

Although steepening the stick for per G gradient was the fix used to increase the pilots ability to safely control the aircraft, the stick force gradient was not the issue with the Spitfire.

The issue was the longitudinal stability was neutral and not positive. That makes for a twitchy airplane that is easy to stall, hard to precisely maintain a load factor in a turn, and easy to overstress the airframe.

3/4 of an inch from cruise to stall is not safe and would not be considered acceptable.

FAA formula for chimp-proof civil aircraft.

That is for all aircraft seeking certification in the United States and since most of us are all on the same standard now, much of the world.