@Twigs: Maybe I can check your statement in a few years, I want to study it.
@Safe-Keeper: Thanks for welcomming(is this a correct formulation )

€dit: Smiley dont works if there is no space before

We then made the decision not to follow the herd and go our own way with this, and Safe above has just given the perfect example of movie reference which really indicates that the S-foils are not linked to speed, the Battle of Yavin trench run. You can bet those fighters would have been going as fast as possible down there. Not to mention earlier in the battle when on approach the X-Wings lock their S-foils in attack positions and then are ordered to increase to attack speed.

If anything can be gleaned from the movies judging by when the wings are closed, it is that the X-Wing's S-foils are opened for battle and closed for landing and cruising speeds. Other lore indicates the reasons for the S-foils being open is to give better coverage with the weapons being a larger distance from each other on each wing tip, and to expose heat sinks to allow them to dissipate more heat allowing the engines and weapon systems to function more efficiently.

So with that in mind we believe we have gone the more lore accurate route with our current X-Wing S-foil set up.

Would be interesting if Twigs (former RAF fighter pilot) elaborated on that.

Twigs is not a former RAF pilot, Twigs is a current RAF aircraft engineer.

Wings sweep backwards in modern jets to increase speed but not how you think. It doesn't make it any more aerodynamically efficient than a conventional wing design. You will notice all current fighter jets have some kind of 'sweep' in the wings, no matter if they can move or not. This is so because as they approach the speed of sound, shockwaves begin to form on the wings, if you sweep the wings you delay the point at which these shock waves form on the wings.

Folding S-Foils in space would not give you any kind of a speed incrase as there is no air to create any drag and so nothing to prevent you hitting high speeds. In atmosphere though that may be slightly different, S-Foils out should increase the amount of lift generated (more surface area) and so be better for slow speeds. Locking S-foils would give a smaller lift area but decrease the amount of drag (since we now have to large surface areas removed), since drag increases at twice the rate of speed increase due to atmospheric pressure, it makes sense to reduce drag as much as possible to better increase your speed.

In other words, if you double your speed, drag will increase by four. So, if you have an object you want to fly rather than increase thrust to increase speed it makes more sense and is more efficient to decrease drag.

I could of course have the facts a little wrong there, this is basic aerodynamics stuff, I last sat through that lesson 12 years ago

Is there any film scene or something else proofing that X-Wing do not fold the wing while flying faster?

The Battle of Yavin. I'd be very surprised if the fighters didn't do everything they could to fly as fast as possible while making that trench run. Race against time to destroy Death Star + TIE fighters in hot pursuit = X-Wings and Y-Wings flying at maximum speed.

I guess it could make sense in atmosphere to fold the wings for going faster (kinda like an F-14 folding its wings backwards, I suppose), but I'm no expert on the subject. Would be interesting if Twigs (former RAF fighter pilot) elaborated on that.

To be honest, though, I always felt it looked kinda silly in the RS games when you had wings constantly opening and closing during combat.

Oh, and welcome aboard, and thanks for the suggestion!

edit: ahk, true, didn't read the boost part properly.