Stability and Control characteristics of the Early Mark Spitfires

[ATAG_Dutch]

Originally Posted by CaptainDoggles

As I was climbing up to altitude I repeated an earlier test that I'd done and, in level flight at ~10000 feet, pulled the stick back and then let go. The aircraft nosed back down gently like a stable aircraft would. It should have held that AOA until it ran out of speed (I was using the rudder to keep wings level), or possibly nosed up further, depending on if you choose to believe it had neutral or negative stability.

How much fuel did you have? The evidence produced states that the spit was longitudinally stable with the CofG forward, i.e. a full tank, with decreasing longitudinal stability as the CofG moves aft with decreasing fuel load.

Personally, I'm very interested as to what the wording of the entry in the Bugtracker will be.

[NZtyphoon]

Originally Posted by CaptainDoggles

Why does it matter, though? Historical trivia does not an engineer make. You can't prove someone isn't an engineer because they haven't heard of Somebody Lanchester.

If Crumpp wishes to make definitive statements and claims, based on a very small amount of evidence there's no reason they cannot be challenged.

Originally Posted by CaptainDoggles

And lastly, not that I really care, but if Britain had a unified standard in the 30s, then why is there a document from 1947 talking about developing one for the first time? I'm sure that the individual manufacturers did indeed have their own standards, but that's not being disputed.

If not for you convenience then I'll answer for others - if you bothered reading the 1938 doco you'll see that aeronautical development had outstripped the standards of the time, from biplane to monoplane, such that the RAE and Air Min were working with the aircraft industry to promulgate better standards. Now, what happened during WW2? Jet aircraft, high speed prop driven aircraft approaching the speed of sound etc etc so now a new set of standards had to be developed and introduced; basically aeronautics and aeronautical engineering were changing extremely quickly from the early to mid 1930s on, so I don't believe that it was possible for even NACA to devise and stick to a definitive set of "standards" in the way Crumpp claims. Think about it - how was it possible to use the same stability and control standards for a 150 mph biplane fighter as for a 450 mph monoplane?

[Crumpp]

same stability and control standards for a 150 mph biplane fighter as for a 450 mph monoplane

NzTtyphoon,

The basis for all modern stability and control was developed during World War II. Outside of Germany, the NACA was the worlds leading organization for Stability and Control.

Fredrick Lanchester did some pioneering work and is considered the foundation for stability and control. He correctly theorized on vortex theory of lift with gliders secured by wire, conceptulized aircraft oscillatory motion which he called "fleeing motion" instead of phugoid. He published several works and even spoke with the Wright Brothers in 1908.

None of this was put into any mathmatical definition. Fredrick Lanchester was not able to put his ideas into any useful mathmatical form.

I have been waiting for you to realize this since you brought it up. I have ignored most of what you write because it is obvious you argue based off emotional attachment and do not understand much of what you claim. It is another red herring like arguing for pages about a non-dimensional proportion.

[taildraggernut]

Despite these apparent 'adopted' standards, both the US and Germany produced aircraft that actually 'did' have dangerous flying qualities.

So the question is, what point are you trying to make with the assertions the British had no adopted standards? that every British aircraft was just a hit or miss lucky guess? all the British aircraft that had stable qualities were just 'flukes'?

[Sandstone]

Originally Posted by Crumpp

:That is the Spitfire's issue. Nobody is claiming it should be less maneuverable. The longitudinal axis should be so maneuverable as to be very difficult to precisely control.

This is where you don't convince me.

The Spitfire certainly did have undesireable pitch stability, but was it enough to make it "very difficult" to control precisely? I don't think it was. I think this because pilot accounts seldom mention longitudinal stability and because low-hours pilots flew it without problem. You obviously think it was, but this interpretation doesn't seem to be backed up by much in the way of evidence and, to me at least, comes over as no more than an assertion. Certainly, nothing convincing has been presented.

You say we shouldn't consider Spitfire pilot acounts. But if we are to determine how much of a problem was actually caused to real Spitfire pilots by the stability issue then that is exactly what we have to do. I can't see any way round this.

[taildraggernut]

I think the little blue sarcastic emoticon shoud be re-named Crumpp.....

[Crumpp]

but was it enough to make it "very difficult" to control precisely?

According to all measured standards, it was....

The Operating Notes also reflect it as well as test pilots from England, United States, and Germany.

[taildraggernut]

intersting article from NASA....

http://history.nasa.gov/monograph12/ch4.htm

[Glider]

Nice one, I like this bit on the SPitfire

FIGURE 4.5. Supermarine Spitfire airplane. A high-performance fighter noted for its role in the Battle of Britain and throughout WW II, the Spitfire had desirably light elevator control forces in maneuvers and near neutral longitudinal stability. Its greatest deficiency from the combat standpoint was heavy aileron forces and sluggish roll response at high speeds.

Crumpp this is a must read for you

[taildraggernut]

Originally Posted by Glider

Nice one, I like this bit on the SPitfire

FIGURE 4.5. Supermarine Spitfire airplane. A high-performance fighter noted for its role in the Battle of Britain and throughout WW II, the Spitfire had desirably light elevator control forces in maneuvers and near neutral longitudinal stability. Its greatest deficiency from the combat standpoint was heavy aileron forces and sluggish roll response at high speeds.

I thought it was worth making the 'desirably' bold too

Interesting to note the 'near neutral longitudinal stability' persumably this is because it was slightly longitudinaly unstable, but not unstable enough as to be regarded a problem.