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MB_Avro
03-30-2004, 08:49 AM
I tried out the P38 and found that when I cut one of the engines there appeared to be no 'swing' effect on lateral stability. Loss of an engine on a twin engined aircraft is a serious matter!

Is it not possible to model this?

(I did notice however that the navigating pencil rolled ok).

Regards
MB_Avro

MB_Avro
03-30-2004, 08:49 AM
I tried out the P38 and found that when I cut one of the engines there appeared to be no 'swing' effect on lateral stability. Loss of an engine on a twin engined aircraft is a serious matter!

Is it not possible to model this?

(I did notice however that the navigating pencil rolled ok).

Regards
MB_Avro

Dmitri9mm
03-30-2004, 08:59 AM
I believe you're right the loss of stability is not great enough when running on one engine.
However, early in the war Bluhm un Voss developed an asymetric a/c with only one engine which ought to have absolutely no directional stability, but it didn't. Well I just don't know.
What they should do first however, is to get rid of the torque on the P-38 while flying on two engines, it shouldn't be there!

I found a picture here, BV 141 meine Damen und Herren:
http://aircraftwalkaround.hobbyvista.com/bv141/bv141_1.jpg

http://www.kenston.k12.oh.us/khs/tplookalike/dude.jpg
Edit: Sig text removed by Tully__

[This message was edited by Dmitri9mm on Tue March 30 2004 at 08:14 AM.]

[This message was edited by Dmitri9mm on Tue March 30 2004 at 08:26 AM.]

jeroen_R90S
03-30-2004, 01:07 PM
{OT}
@Dmitry9: that's one cool movie in your sig... I can still hear Walter say: "shut the f#ck up, Donny!" http://ubbxforums.ubi.com/infopop/emoticons/icon_biggrin.gif

Jeroen

mortoma
03-30-2004, 02:59 PM
Nope, assymetrical forces ain't modelled in this sim..... http://ubbxforums.ubi.com/images/smiley/16x16_smiley-sad.gif

Flightvector
03-30-2004, 04:04 PM
What you propose about assymetric forces is a bit premature, you are trying to make sense of offset thrust visually. The BV assymetric aircraft had no such issues because the engine thrustline coincided (full co-incidence with CG is not optimal due to right-yaw tendencies) with the optimal position with respect to lateral CG. Remember that forces acting on the centroid of mass create no moment, and this aircraft was balanced as such by mass. Think about where you balance a spoon, although the CG is way offset, pushing the spoon at that point creates no tendency for rotation. Logic says the center of the spoon is the best place to put an engine, but this would cause the spoon to start yawing very badly.

As far as equilibrium of aerodynamic drag forces goes, the elevator offset to the left may help balance the cockpit's drag with induced drag (this was really done to clear the gunner's view), aerodynamics are unlikely to have caused issues since the engine was allowed to be the principle fuselage section and the engine/cockpit are offset by a small enough margin that the right-turning tendency of the prop and canted vertical stab could easily make up for this with little drag penalty.

But as far as the P-38 goes, IL-2 FB/AEP really doesn't come close to how bad the assymetric thrust should be, the yaw should be uncontrollable at 160 km/h. Amazingly, the original IL-2 was much better at this, in slow flight, engine torque nearly overpowered aileron forces, which is accurate.

Covino
03-30-2004, 08:18 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Flightvector:
As far as equilibrium of aerodynamic drag forces goes, the elevator offset to the left may help balance the cockpit's drag with induced drag...<HR></BLOCKQUOTE>

Good post, just a small correction though, I believe it's parasite drag. Induced drag is drag generated by airflow around the wing when creating lift.

BlindHuck
03-31-2004, 02:44 AM
The Bv141 originally had a symetrical horizontal stab/elevator. Converted to illustrated form to improve aft gunner's field of fire. Aircraft flew a little differently than a conventional aircraft but not awkwardly at all, and was an amazing solution for an observation aircraft with the cost/maintainane/economy of a single engine aircraft with visability equal to, or better than, a twin.

Sometimes there are more things to consider than just aerodynamics. http://ubbxforums.ubi.com/images/smiley/16x16_smiley-happy.gif

"I race full real exclusively in IL2:The Forgotten Battles." - Mark Donohue