[Fenrir]

Originally Posted by JtD

You're not helping.

Why? I thought discussion and debate helped find the truth?

You have correctly understood that aircraft could be pre trimmed on the ground, even though your understanding is limited to the Spitfire

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How condescending. I know a fair bit about trim and a/c having been 6 years in the RAF cadets, flown a glider solo and generally done my research over the years. I've also got a lot of material on The Spitfire, some old, rare books that aren't widely known and therefore quoted.

However, this has never been a part of il-2. If you want that different, make a feature request, posting in a Spit FM topic is a waste of time.

I'm not after this feature; as in depth and great it could be even I with my incredibly limited knowledge realise what a pig that could be to programme in game.

Currently the aileron pre trim is that the plane can fly hands off stick with no slip in a shallow climb. It requires a little slip to fly straight and level hands off stick over most of the speed range. Your personal preference is different. Tough luck. That's all there is to it.

That's my problem - I DO NOT THINK IT IS CORRECT FOR ANY AIRCRAFT TO BE TRIMMED FOR THE CLIMB. Logically, it seems common sense to me to put the trim neutral state of any flying surface, aileron, elevator, rudder, whatever in the approximate middle of that a/cs speed range or at least at around the combat cruise setting, since then the out-of-trim-forces are balanced at opposite ends of the speed-range.

What I mean by this is if your aircraft is trimmed for the slowest regime of flight at max power, and you go diving it to max speed it'll require a helluva lot of force to keep the a/c attitude.

Arbitrarily say an a/c has a aileron stick force requirement of 20kg when trimmed out in the middle of her speed range. For arguments sake call it 250mph. That means at lowest, e.g. 100mph that should require 20kg of pressure to, let's say, the right against the torque. Similarly at max speed, say 400mph, that required 20kg of pressure is now to the left to compensate for the inherent trimming of the airframe.

Cool. Ok. What happens if we make our datum 175 mph instead? Well down at 100mph against torque we only need 10kg of pressure - however at 400 suddenly you need 30kg of pressure to keep the a/c on keel.

It's counter intuitive to me to think that any aircraft that will regularly fly at any of theses speeds would be so set up to give such variance of 300% in trim forces, and although only an example, reflects my attitude regarding the aileron trim modelling.

If you've never heard about aileron reversal in Spitfires, that's probably what you should research next. Don't waste it on researching individual Spitfire aileron trim settings, 20000 have been built, flown by lots of different pilots under lots of different circumstances, each with individual trim settings. Posting slip free hands off stick speed range for individual planes is therefore meaningless.

I have the Quill book, amongst many others. Nowhere does he say the Spitfire suffered from aileron reversal.

He says given the high speeds being reached by 1944, they would have run into aileron reversal had they continued adding more and more power and strengthening the airframe thus pushing it beyond the 450Vne of the airframe, but absolutely NOWHERE does it state that any operational mark of Spitfire suffered from aileron reversal.