Stability and Control characteristics of the Early Mark Spitfires

[IvanK]

Inertial elevator ??

Are you referring to the bob weight in the pitch circuit or increased balance area on the elevator as fitted to MKV's ???

[DC338]

Can I ask for your analysis of figure 16 17 & 18 of the NACA report? It seems figure 15 was an anomaly when compared to the next 3 which where doing similar test?

Someone (whiny?) earlier quoted a report from the morgan book on the Spitfire about inertia weights being not required for the MK I & II as long as the rear oxygen bottle was removed. Would be interesting to see the full report.

[MiG-3U]

IvanK,
The early version of the Mk II manual, which Crumpp is quoting, is for the planes with Rotol props only before the CoG limits were revised. Later the planes (any early Spitfire) with the Rotol props got tighter aft limits, 7.5" aft datum with atandard elevator and without bob weight, while the planes with the DeHavilland prop only got limitations for extended CoG limits, bob weigh required if CoG 7.9" aft datum. In other words bob weigh was not required for the planes with DeHavilland propeller.

The later manual you are quoting is for the Mk IIs with both propellers, Rotol and DeHavilland, after the CoG limits were revised, hence no warnings about the elevator control reversal. Note that longitudal instability and elevator control reversal are related to each other and CoG but not the same thing.

As pointed out earlier with documentation and calculations, the NACA tested Spitfire had the CoG at 7.8" aft CoG and Rotol prop, in other words the CoG was behind the limits and the results are not representative for all the early Spitfires nor all CoG positions.

[IvanK]

I think the Oxy bottle statement is discussed on P143 of the Morgan Shacklady book.

Here is the bit.



The 30 June meeting discussing the general fitting of bob weights refers only to the MKV.

The Bob weight was initially trailed on the one off Spit MKIII. It was tested also on a single MKII airframe P7280 that features in a lot of the RAE tests.
So unless more evidence is provided there is nothing to confirm that bob weights were actually fitted to operational MKII's

Spin trials by RAE on the MKII and MKI (as posted earlier in this thread) generally considered spin characteristics as normal ... no real drama.

Here they are again !









Thanks Mig-3U more evidence that operational Spit II's wernt fitted with Bob weights.

[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.

[bongodriver]

So.....can we have that 109 thread now?

[Crumpp]

It is very simple NzTyphoon.

Post the standards developed by the ARC.
Thanks!!

"The Development of Airplane Stability and Control Technology" has done no research into British aeronautical development after 1913

Wow,

Let's not be obtuse. I never said there was no research in stability and control.

I said they stagnated into an attitude that flying qualities was an academic exercise and that the pilot's opinion was what was practical.

Big difference from what you are claiming.

The NACA took a different route. They developed techniques as well as equipment to measure and quantify behaviors. Part of that system was training test pilots and developing manuevers to define behaviors within flying qualities. In fact, it was Cooper's experience as a test pilot at the NACA that led to the development of the Cooper-Harper Rating scale.

http://www.google.com/url?sa=t&rct=j...zIxnwH4SfCszng

Are you referring to the bob weight in the pitch circuit or increased balance area on the elevator as fitted to MKV's ???

No, I are referring to the one fitted to Spitfire Mk I's to correct the longitudinal instability.

[bongodriver]

No, I are referring to the one fitted to Spitfire Mk I's to correct the longitudinal instability.

Never happened, only the MkV was 'ever' fitted with a bob weight.

I said they stagnated into an attitude that flying qualities was an academic exercise and that the pilot's opinion was what was practical.

God forbid that when designing something to be operated by a human you would ever actually ask those humans for any advice.

I wonder why on some adverts the slogan 'designed by XXX for XXX' is used, it's almost like the oppinion of the end user counts for something.

[NZtyphoon]

Originally Posted by Crumpp

It is very simple NzTyphoon.

Post the standards developed by the ARC.
Thanks!!

Having wasted hours trying to get Crumpp to provide some documentary evidence to prove his cock-eyed theories on 100 octane I am not interested in complying with these demands.

Originally Posted by Crumpp

Wow,

Let's not be obtuse. I never said there was no research in stability and control.

I said they stagnated into an attitude that flying qualities was an academic exercise and that the pilot's opinion was what was practical.

Big difference from what you are claiming.

Let me complete that for Crumpp:

"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

The only one being obtuse is Crumpp, who tried to use an irrelevant paper to bolster his "case". Anyway I'm done wasting time on Crumpp flogging his dead horse and pointless bug tracker - he can waste as much time as he likes here.

[Crumpp]

Spin trials by RAE on the MKII and MKI (as posted earlier in this thread) generally considered spin characteristics as normal ... no real drama.

Except that spins are prohibited.

They never changed the Operating Notes. It is not because they are lazy. Nor is it because they want to "reduce risk" by not training their fighter pilots in spin/upset/unusual attitudes.

Spin training, upset, and unusual attitude training is essential to a fighter pilots core mission.

I said from the begining, any engineer can look at a design sitting on the tarmac and know if the airplane has a high chance of normal spin recovery assuming the CG is normal or forward. The Spitfire has all the characteristics required to spin normally.

Therefore, the only real issue is the longitudinal instability.

The never changed it because a high speed dive is generally the result of spin recovery and a Spitfire pilot could break the airplane rather easily.



I was just curious if spin trials were done after the longitudinal instability was fixed in the Spitfire Mk I's.

The approval to train after being checked out by a Squadron Commander or CFI at an OTU certainly did not appear until the airworthiness directive fixed the instability.