Stability and Control characteristics of the Early Mark Spitfires

[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?

[NZtyphoon]

Reading the bibliography to the text of a lecture delivered in 1970 and referred to by Crumpp as definitive proof of Britain's lack of control and stability standards: Development of Airplane Safety and Control Courtland D. Perkins
(http://forum.1cpublishing.eu/showpos...&postcount=837)





The references stop at an ARC paper PUBLISHED IN 1913 - NOT ONCE does the author refer to the ARC papers from 1937 through to 1939-48, nor does he have any references concerning British research during the war years, instead concentrating almost exclusively on American aeronautical research - he had no idea of what sort of development the British had put in after 1913: this one is busted.

I wonder what we would see if we looked at the bibliograpies of most of the books referenced by Crumpp - how many of them concentrate on American research, ignoring Britain?

[Crumpp]

Reading the bibliography

NzTyphoon,
Why do you keep confusing individual research with an established standard for all????

You obviously cannot differentiate between the two.

It is a fact, there was not an established standard for stability and control in the United Kingdom during WWII.

Glider,

You have constructed so many fantasies and misconception about this I don't even know where to begin.

Read the report. It is measured and defined.

What do you have an issue with?

You really don't need much to understand it. You can read the plain English text for the warnings in the Operating Notes, right??

You seem to deny they exist and keep accusing me of making something up?

As for spin recovery, is it so difficult to understand recovery ends in a dive?

Read the Operating Note warnings!!!

Although the POH is the primary reference for recovery from a spin, the following can be used as a general procedure:

P - Retard the throttle to idle. In most aircraft, power hampers the recovery.

A - Ailerons neutral. Many pilots will attempt to recover from the spin using the ailerons. This may actually make the problem worse.

R - Apply full opposite rudder. Apply rudder opposite the rotation of the spin. If you have trouble determining which way the airplane is spinning, look at your turn coordinator or turn needle. It will indicate the direction of rotation.

E - Apply forward elevator. Immediately after applying opposite rudder, apply a quick forward motion on the control yoke and hold anti-spin controls until the aircraft starts to recover.

D - Recover from the dive. Once you have completed the four previous steps, and the rotation stops, recover from the dive. The descent rate may be over 5000 feet per minute and the airspeed will rapidly exceed redline. Remember to neutralize the rudder after the rotation stops.

http://www.aopa.org/asf/publications...tall_spin.html

Go out and do some spins in the an airplane, please!!

Make sure it is not approved to spin and leave the chutes on the ground. <joking>

[Crumpp]

NOT ONCE does the author refer to the ARC papers from 1937 through to 1939-48, nor does he have any references concerning British research during the war years, instead concentrating almost exclusively on American aeronautical research - he had no idea of what sort of development the British had put in after 1913: this one is busted.

Why don't you post the ARC standards.

Here is the NACA standards adopted during WWII. The USAAF and USN used these as the basis to define their own standards by 1944.

Until those individual service standards were adopted, they used the NACA's.

One impor-tant contribution made by the NACA in this area was its famous technical report, No. 755, "Requirements for Satisfactory Flying Qualities of Airplanes." Representing a decade of work, the NACA introduced to the industry a new set of quantitative measures to characterize the stability, control and handling qualities of an airplane. The military readily adopted the NACA findings and for the first time issued specific design standards to its aircraft manufacturers. It is a classic example of the partnership between the military, air-craft industry and the NACA.

http://www.nasa.gov/centers/langley/...s/WWII_prt.htm

End the speculation and just post the standards during the war for the ARC.

Thanks!!

[NZtyphoon]

Thanks Ivan.

Originally Posted by Crumpp

NzTyphoon,
Why do you keep confusing individual research with an established standard for all????

This mumbo-jumbo is an example of Crumpp's intellectual dishonesty coming to the fore - the document he has cited in an attempt to bolster his "case" has nothing to do with the point he is trying to prove. "The Development of Airplane Stability and Control Technology" has done no research into British aeronautical development after 1913 and, as such, it has nothing whatsoever to do with the Spitfire's longitudinal stability. Crumpp has not bothered evaluating the sources used by a publication before citing it as "evidence" - this is one of the basics of historical research.

During October 1944, the National Advisory Committee conducted a series of conferences with the”Army, Navy, and representatives of the aircraft industry for the purpose of discussing the flight-test procedures used in measuring the stability and control characteristics of airplanes. The conferences were initiated by the Army Air Forces, Air Technical Service Command, to acquaint the flight organizations of the industry with the flight test methods employed by the NACA and to standardize the techniques insofar as possible as they are employed by the various manufacturers and agencies engaged in determining the flying qualities of airplanes.

So, while NACA had formulated a set of specifications they had yet to be properly standardised because as late as October 1944 NACA was still discussing how to implement the specifications with representatives of the Army, Navy and aircraft manufacturers. This does not say anything about the specifications being adopted in 1944 - just being discussed pending adoption.

Now, Crumpp insists on an Aeronautical Research Committee report confirming British standards in control and stability; what Crumpp doesn't seem to realise is that the ARC is an advisory body which works to distribute information and reports to the likes of the National Physical Laboratories, RAE and manufacturers (para 2 Policy of the Committee). Unlike NACA it does not do its own research: unlike NACA papers on stability and control can only be accessed via archives such as this entry, NA Kew.



Reports tabled in ARC report 1939:


As it is bug tracker #415 won't be gaining any traction at any time soon, so there isn't much future in pursuing this thread any further.