Fresh stuff from sukhoi.ru (Discussion)

[ACE-OF-ACES]

Originally Posted by Insuber

Dynamic Stall: go to Wikipedia if you want. Today only the normal stall is modeled - not good for a flight simulator.

Ok looking at the wiki, i.e.

wiki dynamic stall:
Dynamic stall is a non-linear unsteady aerodynamic effect that occurs when airfoils rapidly change the angle of attack. The rapid change can cause a strong vortex to be shed from the leading edge of the aerofoil, and travel backwards above the wing. The vortex, containing high-velocity airflows, briefly increases the lift produced by the wing. As soon as it passes behind the trailing edge, however, the lift reduces dramatically, and the wing is in normal stall

Based on that looks like ElAurens is close to the mark.. basically an accelerated stall situation.. Thing that is interesting is it also states you get a brief increase in lift.. So other than the brief increase, it follows the standard stall def

Also note the wiki reference #22 is from here

Unsteady aerodynamics
Dynamic stall is a phenomenon that affects airfoils, wings and rotors in unsteady flows. It is due to changes, periodic or not, in the inflow conditions and/or angle of attack. In some cases, such helicopter rotors in advancing flight, dynamic stall is intrinsic to their state of operation.

A comprehensive review of CFD methods for dynamic stall has been published by Ekaterinaris and Platzer (1997); for physical insight, see McCroskey (1981).

In wind turbines it is the result of atmospheric turbulence, wind shears, earth boundary layer, etc. The aerodynamic characteristics are affected to an extend that depends on the frequency of the changes, their amplitude and the point of operation.

Other factors affecting dynamic stall are the Reynolds and Mach numbers and the geometrical shape. There other, maybe minor factors, like the vortex effects, blade flapping and bending, etc...

In the following discussion we will consider the airfoil dynamic stall, which is a particular case of rotor and wing stall. The airfoil is subject to two fundamental periodic oscillations: plunging and pitching.

A plunging oscillation is a periodic translation of the airfoil in a direction normal to the free stream. A pitching motion is a periodic variation of the angle of attack.

Looks like Skoshi hit close to home on that with the helo rotors.. Also reading that I get the impression this is geared more for a computational fluid dynamic (CFD) flight model than the standard 6DOF flight model.. Where the change in the atmosphere has more affect.. The question is will the user even notice the effect? That is to say at the design level it may be noted, or during flight testing it might show a spike in the data.. but would the user of the flight sim notice it?

All in all it appears the standard def of stall still applies in both, just the changes/turbulence due to the atmosphere causes it to stall a little sooner or little later depending on the situation

Originally Posted by Insuber

GUI: RoF is a good example.

example of what?

Originally Posted by Insuber

Bullet damage to radiator: you can fly for a lot of time despite the message "radiator leak", at least in the 109, imo it is a bug.

It would be a bug if it could fly forever.. In that I don't know if there was any sort of self sealing radiators in WWII?

[BlackSix]

So, what can I do with Dynamic stall? Remove the question?

question 12, new form:
Will the GUI be remade?
ok?

[furbs]

Yes...B6 and ask if we will see FSAA in CLOD, or where are the 2D clouds?

[ACE-OF-ACES]

Originally Posted by BlackSix

So, what can I do with Dynamic stall? Remove the question?

Please don't based on what I said! I was just curious as to it's meaning!

[Insuber]

Originally Posted by BlackSix

So, what can I do with Dynamic stall? Remove the question?

No better, remove Ace of Aces

Originally Posted by BlackSix

question 12, new form: Will the GUI be remade?
ok?

I would reformulate it like this:
question 12: will the GUI be optimised, to be less clumsy and more ergonomical (today you need several clicks to do simple things), in the same way that RoF optimized their GUI? Today RoF is a great exemple of an appealing, sexy and functional user interface.

Cheers!

[ACE-OF-ACES]

Originally Posted by Insuber

No better, remove Ace of Aces

Ah ha.. So is it safe to assume that input was one by you?

Eitherway it will be telling to see Luithers reply to it!