Stability and Control characteristics of the Early Mark Spitfires

[camber]

Thank you for your post, Crumpp

Originally Posted by Crumpp

This thread is going to cover the definable and measure stability and control characteristics of the Spitfire. It is not going to cover opinion outside of stability and control engineers.

Defined like that, any argument is rather moot. If it is defined that the only stability and control engineers at that time were in the US (specifically associated with NACA), and they formulated standards which the Spitfire failed, then the Spitfire failed...as defined in this rather narrow question.

I believe that the work of the pioneering stability and control engineers was interesting and valuable for the future of aviation. But the Spitfire seems to be a bad example to demonstrate that value.

As opposed to the objectively derived flight stability data, the standards that NACA set were subjective (e.g. X inches in control deflection to perform Y). Defensible, intuitively correct, but subjective.

Despite failing these subjective standards, many records exists describing the Spitfire handling as (subjectively) good. Many descriptions exist of Spitfire first flights by novice pilots. Some note the Spitfire pitch issues (e.g "found it easy to black myself out"), but express relief at finding the aircraft benign to fly and push hard.

I realise that you want to exclude all these considerations as being mere anecdotes. But then what it is the argument? I think we all agree that NACA failed the Spitfire on certain aspects of it's flight stability. To determine what that meant, we have to go further.

I think the Spitfire is not a good example of the value of the advances in stability and control. Despite it's rather alarming characteristics in the NACA reports, the young humans sitting inside RAF Spitfires were capable of rapidly adapting to them and making the Spitfire what it was intended to be ..a superlative short range military interceptor.

camber

[Crumpp]

If it is defined that the only stability and control engineers at that time were in the US (specifically associated with NACA), and they formulated standards which the Spitfire failed, then the Spitfire failed...as defined in this rather narrow question.

Gates was not NACA and neither was the RAE when they published the Operating Notes.

Spitfire is not a good example of the value of the advances in stability and control.

It is not meant to be a good example of advances in stability and control. The thread is meant to point out the measureable and definable characteristics so that they can be modeled for the game.

[camber]

Originally Posted by Crumpp

Gates was not NACA and neither was the RAE when they published the Operating Notes.

I read the notes. Do you consider that the warnings against misuse are exceptional for the period, or exceptional compared to later WWII aircraft with better stability characteristics?

Originally Posted by Crumpp

It is not meant to be a good example of advances in stability and control. The thread is meant to point out the measureable and definable characteristics so that they can be modeled for the game.

That is a good idea and worth pursuing, but there is an unfortunate snag. Not only are people using different control hardware to control the same virtual aircraft, they have the option to tune the response between the physical control deflection and the virtual control surface deflection with nonlinear curves. This ability is not under the umbrella of the flight sim software itself. Some people have simulated control surface loading (FFB), some do not, and again the user can quietly do their own stability modifications to make their plane handle differently to what the devs attempt to program.

camber

[CaptainDoggles]

Originally Posted by camber

That is a good idea and worth pursuing, but there is an unfortunate snag. Not only are people using different control hardware to control the same virtual aircraft, they have the option to tune the response between the physical control deflection and the virtual control surface deflection with nonlinear curves. This ability is not under the umbrella of the flight sim software itself. Some people have simulated control surface loading (FFB), some do not, and again the user can quietly do their own stability modifications to make their plane handle differently to what the devs attempt to program.

Yes and no. The user can dampen their inputs to the aircraft (e.g. very flat curve around the center), but the user cannot affect the aircraft's response to said inputs. If the aircraft has a tendency to diverge from equilibrium, then it will still do so regardless of what the user's stick curve looks like. A high-wing monoplane like the Storch will still be very stable in the roll axis due to the keel effect. An aircraft with a lot of anhedral is still going to be largely unstable about the roll axis.

Keeping in mind of course that real control columns have a much greater throw than your average consumer-level HOTAS.