Stability and Control characteristics of the Early Mark Spitfires

[Crumpp]

There are such warnings for American a/c.

Really, by god....don't model it, we might see "porked" american fighters....



Quick, withdraw the facts about the Spitfire!!! Run!! There will be revolution!!

[NZtyphoon]

Originally Posted by Crumpp

The aircraft's reaction to gun recoil could also be modeled. As an unstable platform, the arm is shorter which means less resistance to motion.

Documented evidence for this, please.

Alex Henshaw's comments make interesting reading on the Spitfire as a gun platform and on its elevators:



Note Henshaw comments that the Spitfire's elevators were light cf those of the Tiger Moth or Magister on which pilots trained....

Now, a comment on the Pilot's Notes used by Crumpp which can be found here: http://www.scribd.com/doc/4598146/Pi...lin-XII-Engine - this is a most unusual set of PNs, even for a reproduction. For one thing these have detailed information and comments on combat skills and aerobatics, which few pilot's notes normally had.






These were not the standard PNs issued to pilots on frontline units - those ones invariably had blue covers: the notes that were issued to trainee pilots at OTUs had orange covers and these notes were conservative in their approach to ensure hotdog young pilots, who had gotten used to heavier elevators on the Tiger Moths etc, were made fully aware of the lighter Spitfire controls.

Originally Posted by Crumpp

Again, the RAE may have blamed it on that (overloading at a squadron level) but they were also behind in Stability and Control research.

Wrong, once again, as Jeffrey Quill made quite clear he witnessed what had happened - unless Crumpp can show that he knows better about what happened in 1942 than Quill...nothing but speculation.

As for Crumpp's continued assertions about how hapless the Brits were when it came to defining control and stability? The first page shown by Crumpp is talking about 1910-1912: it has no relationship to the 1930s and the Spitfire whatsoever!
This is page 5 from the Von Karman Lecture 1970:


Page 6 - the one posted by Crumpp


What has what happened in1910-1912 got to do with ANYTHING in this thread???

CF: 1937 ARC report





CF: the 1939-48 ARC report

[Crumpp]

Do you read what you are highlighting or posting?

The Operating Notes almost verbatium repeat the exact same warning for the Spitfire Mk II AS THE MK I.

In fact, you have saved me the trouble of posting them.

What has what happened in1910-1912

Bryan's theories were developed before WWI but the attitude that pilot's determine flying qualities over the engineer persisited until after World War II.

It was not until AFTER World War II that the ARC developed a standard that all designs had to meet.

That is a fact.

The article you posted points this out.

First it concludes that the Aeronautical Research Council made the mistake of regulating stability and control engineering to an academic exercise leaving the practical to the opinion of pilots. Exact same thing the AAIA article I posted relates.

Then, the ARC concludes that a foundation was laid during the war for estabilishing a defined set of standards for stability and control.

[Crumpp]

Documented evidence for this, please.

MMM, It is in the thread already. Read the stability characteristics of the Spitfire. You seem to not understand it or ignore it. Instead, you place more value on anecdotes which are impossible to quantify.

You also quote the lone voice in the wilderness from Alex Henshaw who never fired a shot in anger.

Let's get some from guys who flew both in combat:

This is the reality. The Longitudinal stability is a defining characteristic of the early Mark Spitfires. It is part of what makes the airplane unique and gives it personality.





Wow, check that out. The first pilot could not make a kill because when he touched the firing button, the nose pitched down due to the longitudinal instability.

The second pilot disliked doing aerobatics. He felt the ailerons where too stiff, the elevator to sensative, nose too long, and the cockpit too cramped.

You can google "Hurricane vs Spitfire gun platform" yourself and not the results. A defining characteristic of the early mark Spitfire is it's twitchiness as a gun platform. Yes, it too, is a function of the longitudinal instability.


The Spitfire was not a an airplane for the inexperienced or average pilot. It was a pilot's aircraft and demanded skill. For that skill, it rewarded those who mastered it with exceptional performance. That breeds affection.

robtek says:

I think of the Spit like a Porsche 911, a great car which is a delight to drift around corners, but you really have to work to hold the thin line before it bites you in the a**.

With a regular driver it is still a great sportscar and outperforms many of its competitors, but to have the edge you have to be a pro.

The same will be with the 109, where the pilot has the opposite problem of too high stick forces at high speeds.

Each needs his own tactic to use the quirks of ones plane for optimum efficiency.

Good analogy.

IMHO, the generalize the three fighters of the BoB....

The Spitfire is sportscar. The Hurricane a workings man's tool.

The Bf-109 is a shooting platform for a machinegun with an airplane built around it.

[Crumpp]

Crumpp can show that he knows better about what happened in 1942

It does not require my opinion.

This is all measured and defined by the NACA, the same characteristics appear as warning in the Operating Notes, and are repeated in a flight testing as well as anecdotal evidence.

My suggestion would be to go school and take some aerodynamics classes.

[BTB]

Sorry but have u read these articles?? These are first impression of a Pilot flying a new and different type of Plane. Of course it reacts totally "unnormal" as what he imagines and knew from the Hurricane.

And just because the Spit reacts quickly on a pitch input doesnt mean that she is a unstable gun platform in my opinion.

Thats why u practise as a Pilot to understand the plane and get used to it.

And thats why u have planes for "rookies" and "experts". But u can't compare or mess this with data because every Pilot has his own flying Skill and learning curve.


wikipedia: "Longitudinal stability

The longitudinal stability of an aircraft refers to the aircraft's stability in the pitching plane - the plane which describes the position of the aircraft's nose in relation to its tail and the horizon.[1] (Other stability modes are directional stability and lateral stability.)

If an aircraft is longitudinally stable, a small increase in angle of attack will cause the pitching moment on the aircraft to change so that the angle of attack decreases. Similarly, a small decrease in angle of attack will cause the pitching moment to change so that the angle of attack increases.[1]"

[NZtyphoon]

Originally Posted by Crumpp

Again, the RAE may have blamed it on that but they were also behind in Stability and Control research. The NPL pretty much stagnated until the efforts of Gates and Lyons came to fruition post war moving AWAY from the conclusion stability and control could not be defined without pilot input.

Crumpp's story has now changed from a blanket statement that the British had no standards on control and stability to one saying that the British "moved away from the conclusion stability and control could not be defined without pilot input."

The Americans no longer needed pilots because their know-all engineers could design perfect aircraft without any input from pilots whatsoever. Just pop an engineer into the cockpit...leave the pilots twiddling thumbs on the ground.

Originally Posted by Crumpp

You have hit upon the entire reason the Air Ministry did not have stability and control standards outside of pilot opinion.

So why, pray tell was lack of pilot input such a wonderful development? Because it was purely subjective! Ignorant pilots could not quantify that seat of the pants feeling, nor could they accurately report on what had happened because they were too busy flying and controlling the plane.

Originally Posted by Crumpp

That all changed with the advent in the powerful monoplane fighters of World War II. The speed and forces involved pushed the science of stability and control to the forefront.

Which is exactly what the British were saying in 1937


and 1938

Originally Posted by Crumpp

MMM, It is in the thread already. Read the stability characteristics of the Spitfire. You seem to not understand it or ignore it. Instead, you place more value on anecdotes which are impossible to quantify.

You also quote the lone voice in the wilderness from Alex Henshaw who never fired a shot in anger.

Meaning that Crumpp has flown a Spitfire and fired its guns in anger - albeit in a flight sim - and knows more on the subject than Henshaw, who had simply spoken to Spitfire pilots about its qualities as a gun-platform. Then he goes into anecdotes which cannot be quantified and happen to be from pilots who had gotten used to the Hurricane and showed a certain amount of prejudice





As well as this Crumpp also claims that he knows better than Jeffrey Quill why Spitfire Vs were fitted with inertia weights:

Originally Posted by NZtyphoon

Slight correction on the Mk V - the reason the inertia weights were added was to help overcome a problem with poor cg loading at a squadron level, plus the added weight of new equipment not used in Spitfire Is and IIs.

and the reply...

Originally Posted by Crumpp

Again, the RAE may have blamed it on that but they were also behind in Stability and Control research.

[Glider]

I was struck by the observation the British made that in the past they had relied too much on a thoretical view, which is exactly what Crumpp has, a theoretical view.

Crumpp has been adivsed of the late 1980's approach to this topic ie that its a blend of theory, handling and an awareness of the mission being undertaken. These more modern standards he has ignored

He keeps saying that the Spitfore broke up easily in a spin which is why it was banned in the Pilots Notes. Unfortunately he has yet to produce one example of such a loss. I should add that I expect there to be a few but the fact that Crumpp has failed to produce one says a lot

Crumpp also says that the Spitfire was prone to structural failure due to stability issues, but so far he has yet to produce one example. Again I should add that I expect there to be a few but the fact that Crumpp has failed to produce one says a lot

He has also made reference to piles of bent wings awaiting repair in the BOB but has yet to find one example

Crumpp has failed to produce any evidence that the level of instability was dangerous. Much is made of the fact that the pilots notes warn of this, rightly, but no comment that the notes worked as proven by the lack of crashes.
No comment has been made has been made that Pilots notes err on the side of caution, we only have a catastrophic reading.

There clearly was a problem with the Mk Vb and bob weights were introduced on operational aircraft until a better solution was found. The evidence is that this was caused by poor loading in the squadrons but it didn't matter the problem had to be solved and it was. Even her Crumpp insists that this was a problem from the start and bob weights were introduced into all early versions of the spitfire. UNfortunately no evidence has been put forward to support this view. INdeed what has been posted is clear that the Mk I and II were not impacted by the problem.

Much is made of the fact that the Spit wasn't a good gun platform, something that is hardly new and that some pilots were afraid to fly it. A contridiction if ever there was one. If the plane was so unstable why did the pilots love it? However he doesn't mentin that in the same document that the pilots loved the aircraft.
The British were so far behind the times apparently re stability and to prove this he uses a pre WW1 document, a time when they didn't know how to deal with a spin?

Crumpp makes much use of this type of statement

It does not require my opinion.
This is all measured and defined by the NACA, the same characteristics appear as warning in the Operating Notes, and are repeated in a flight testing as well as anecdotal evidence.
My suggestion would be to go school and take some aerodynamics classes.

A few observations on this
a)NACA were using a Mk Va, an old aircraft, known to be the one most suseptable to stability problems, one without a crew up to date with the latest rules and regs in the UK. They did their mesurements but even here, they never said that it was a danger, they did say it didn't meet their normal standards but they didn't say it was a danger. If they had thought it was that bad I am confident they would have said so as Americans are not known for holding back unpleasent truths.
b) No one denies that the Spit wasn't perfect which is why the Pilots notes say what they say, but I repeat they always are cautious.
c) Comments about flght testing. I have asked Crumpp often to supply any flight test from any nation (including Germany) who found this aircraft dangerous this question is still outstanding.. I can only conclude that he has no evidence and by saying this he is exagerating his case
d) Going to classes on aerodynamics. Crumpp may or may not have had some training in aerodynamcis, I don't know.
I do know he offerred to debate longitudinal instability by a number of standards. Unfortunately one of these was to do with roll rates for differing types of aircraft and one was to do with the Rules and regulations about ordering spare parts to stop counterfit parts entering aircraft. Again I believe he was trying to exagerate the strength of his position

Above all of this is the lack of accidents. All the issues he talks about are serious safety issues but we have a serious lack of any incidents.

I bring you back to the first point in this posting.
I was struck by the observation the British made that in the past they had relied too much on a thoretical view, which is exactly what Crumpp has, a theoretical view.
Crumpp by not considering the views and experiences of those who flew the aircraft is relying almost totally on a theoretical approach. The standards of the late 1980's emphasise the importance of mixing theory, hands on experience and the task the plane was designed for, by ignoring this he is making the same mistake the British made in the 1920's. The last ones that I used are MIL-STD-1797a but these may have been modified

[robtek]

.....
Above all of this is the lack of accidents. All the issues he talks about are serious safety issues but we have a serious lack of any incidents.......

There might be hundreds of Spitfires being lost over sea or behind enemy lines because of mishandling in stress situations, all disregarded because being accorded to enemy action.
Nobody knows that for sure.
The only data we have is a per se incomplete list of researched accidents.

[bongodriver]

I heard that some Spitfires were pink, maybe they should all be pink?