What's going on here?...

In the 3 screens that follow, the first made with XPFR's excellent Robin DR-400 and the other 2 with Morten's also excellent Piper Archer III, we can see how deep the simulation of airflow, in this particular cases - slipstream from the prop - is simulated in X-Plane10.

Different aircraft will show different results, depending on many factors such as the configuration of the prop itself, the engine that drives it, the airplane geometry, etc...

As you probably already know from X-Plane's Manual, the green and yellow vectors show force resultants both on horizontal and vertical surfaces. Red vectors show drags.

The 1st screen shows the DR-400 with parking brake set and almost full throttle. In (A) you can see the resultants at the root of left wing, from the spiraling slipstream hiting that wing from bellow. ( B) shows part of the fuselage being pushed to the left by the same spiralin slipstream hiting it's right side from above. © shows the vertical tail surfaces (fin and rudder) being pushed right (and thus nose left) by the sma spiraling slisptream hiting the surface asymmetrically from the left, and finally in (D) you can see the right side of the horizontal stab and elevator being pushed down still by the same stream! Whow!!!!

As the aircraft starts it's takeoff roll, and eventually gets airborne, most of this will change... See for yourself :-)

The 2nd and 3rd screens were taken with the Archer III by Morten, and show different resultants because it's a different airplane and engine and prop. On both, before starting the takeoff run and then just after getting airborne, you can easily observe the effects of the spiraling slipstream asymmetric hit of different airplane structures, with the left wing, near the root, showing a resultant higher than the corresponding one on the right (starboard) wing, again because of the stream pushing the left wing from bellow. In the last picture it's not evident, but although the resultant in the vertical fin/rudder has decreased considerably, it is still there.

This is really a GREAT SIM!!!!

;-)