Yakcopter or Automatic flaps? + Video

[6./ZG26_5tuka]

Well the Yak-52 presented in the dev dirary is a miltary trainer and too uses a pneumatic, split flaps system. Still I agree there's a bunch of technical differences that don't make the behaviour of the Yak 52 apply to all planes in BoS 1:1.

Especially the 109s are very innteresting in that matter because not only of their unique flaps mechanism but also because the air flowing threw the coolin inlet is being deflected downward the more flaps are deployed.

 

The theory about prop wash being too efficient may unrealistic. To some extent I kind of feel it too dominant on pretty much all fighters, the Yak and Bf109 F in particular. Don't know how to test this, not to mention quantify it.

[Kurfurst]

The flap wheel goes anticlockwise when deploying the flaps which is correct. However, you need to turn the trim wheel clockwise to counter the nose-up trim we see in BoS.

 

So something basic is obviously off with the flap modeling in BoS since the trim change due to flaps leads to the opposite effect as IRL……

 

That is correct, deploying flaps caused nose-heavy trim in the 109.

 

http://kurfurst.org/Tactical_trials/109E_UKtrials/Morgan.html

 

4.12. Approach. – The stalling speeds when gliding are 75 m.p.h.* with flaps and undercarriage up and 61 m.p.h. with flaps and undercarriage down. Lowering the flaps makes the ailerons heavier and very slightly less effective, and gives rise to a fairly large nose-down pitching moment which can, however, be readily corrected owing to the juxtaposition of the flap and tailplane adjustment operating wheels ; the attitude of the aircraft at constant airspeed changes by about 10 deg. when the flaps are put down. Lowering the undercarriage causes only very slight nose-heaviness.

[Holtzauge]

From dev update:

 

http://forum.il2sturmovik.com/topic/168-developer-diary/page-3?do=findComment&comment=315273

 

“This small experiment shows that plane behavior in the game after landing flaps extension is much like real plane behavior with a similar airframe and flaps. Two different effects happen simultaneously: the force affecting the flight stick pulls it from pilot while the plane, because the flight stick is fixed, pitches up. If pilot won't compensate for the stick movement forward, the plane will pitch down. However, in the game you don't have this feedback caused by downwash and joystick won't move by itself as it should, causing the plane pitch up instead. It's a limitation of not 'feeling' the simulated plane like you would do a real one.

 

The only issue remains is that the effect that pulls the stick from you isn't modeled on Force Feedback joysticks, we plan to address this sometimes in the future."

Looks like the devs mean that since our desktop controller stick is ”fixed” this means that the pitch up behaviour we see in-game due to flap deflection is correct. However, this argument seems inconsistent:

 

The sim does model the effects of changing trim due to trim tab deflection: If you change trim tab position on a plane with elevator trim tab, this moves the virtual stick even though the controller stick is “fixed”. But from an aerodynamic perspective, both the flap deflection and the trim tab deflection have the same effect on the elevator hinge moment: They will both IRL cause the elevator to move to a new position thus affecting the planes behaviour in pitch. So saying that the planes behaviour in the sim is correct is in fact inconsistent since it is only correct if you assume that the virtual sim pilot will counteract the change in elevator hinge moment due to flap deflection but will allow the stick to move if the change in elevator hinge moment is due to a trim tab deflection.

 

A more fair way of describing the pitch up we see in the sim would be so say that the change in elevator hinge moment due to trim tab deflection has been modeled while the change in elevator hinge moment due to flap deflection is currently missing.

 

So, to set this right "the effect that pulls the stick from you" with flap deflection should not only be modeled for force feedback sticks but for ordinary controllers as well.

 

The upside of this would be a more realistic in-game pitch down instead of pitch up with flap deflection and that the Me-109 trim wheel will turn in the same direction as the flap wheel to regain trim, just like it did IRL......

Edited December 25, 2015 by Holtzauge

[Matt]

That's true. 

 

The current way of modelling, is indeed inconsequential and confusing. At the very least, the stick should not stay fixed, when extending flaps. Since they plan to change this for FFB sticks in the future, maybe this will also carry over to non-FFB sticks (to be honest, i don't see how it wouldn't apply for all sticks in general).

 

I think this change could also affect the usefulness of the flaps during combat in general. Right now, when you drop flaps, you basically just increase pitch up, making it especially useful in a turnfight. If you can't get behind the enemy, just drop flaps and you will automatically turn tighter without moving the stick. If the stick would instead drop forward, modelling the nose-heaviness, you would be forced to counteract that with the elevator to stay behind your opponent. It probably wouldn't cause a huge difference, but it's one of the things that currently makes flaps more useful than they should be.

Edited December 25, 2015 by Matt