Large Amount of Yaw to the Left

[Dominique]

. I wonder what's the effect is all about?

-Esa

about your setup 'cause I don't see any of that. The Comanche needs some right rudder during the roll then gently climbs straight with small corrections due to the wind. Same with the 182.

[AKar]

But how can it be? No control movement to cause that.

-Esa

[Dominique]

That I don't know ! One thing is sure, your controls are unlocked. With the Comanche bungee cord, no need to verify the checklist

If you fly P3Dv3, have you recalibrated all your controls with their new interface because that was sorely needed?

[AKar]

The effect was there on 2.5, and also now as I recently upgraded to 3.3. I'll re-check my calibrations, but it shouldn't be a problem. In that sense, I've always put the blame on my technique, but yet I've wondered if there really would be that strong yaw swing when leaving the ground, and if there is, why? It appears to happen regardless of how "carefully" I leave the ground, almost as if scripted.

-Esa

[Dominique]

almost as if scripted.

-Esa

From 2.5 to 3, LM changed the calibration process (for our sins ?). I found after a couple of crashes that the rudder throw was half of what it was in 2.5 (64 instead of 128) and that an axis had a double assignment (aileron or rudder I don't remember). So reviewing the whole shebang is a must do. Using the Thrustmaster Warthog with CH pedals. No trimwheel.

But some other people seem to have this problem with different A2A aircraft and the feeling one has reading their posts is indeed that the roll to the left seems scripted. And most of the time deleting the .dat file and r-eupdating seems to help. Again the 182 and Comanche are gentle planes, the climb out is smooth and straight all the way down and up.

[AKar]

Yep, went through my axis when going to v3, they should be just well.

The effect is not a roll, but almost a pure yaw swing to the left when the airplane leaves the ground, taking maybe 40 % rudder to compensate for, but I need to check the actual position.

-Esa

[Dominique]

Your rudder trim is reset before take off, from what it was at the end of the last landing ?

[AKar]

Yep. Its position is not memorized, it appears, and even if it was, I routinely zero it when leveling out and leave it there. Sometimes I even check that it's zeroed before takeoff!

-Esa

[Dominique]

The only explanations left are a controller acting up or a corrupted file after an update then.

[AKar]

Not sure, there must be something fishy going on - we are speaking of two completely different installations and both act identically. No control problems whatsoever, and the movements are fine.

I've always thought it is a "feature", but if you're not having it, I must start troubleshooting it! If I accidentally have some aileron input when leaving the ground...could it be that the adverse yaw is excessive in the simulator when the control points break? That could easily happen, because my joystick placement is far from optimum.

-Esa

[Nick - A2A]

I initially wondered if the "yaw swing" on lifting the nose during take-off in the A2A 182 was a bit excessive, but then I came across this video which was linked on the forums a while ago...

[youtube]http://www.youtube.com/watch?v=gzxt2SzOsAY[/youtube]

The "dipsy doodle" which is depicted in the vid, and which Martha King describes, is such a good match for the way the A2A 182T behaves that any suspicions I had were allayed. As I understand it, p-factor is the main force at work here, pushing the nose to the left as the angle of attack is deliberately increased at rotation. (I gather gyroscopic precession would actually tend to counter this force somewhat, though presumably not by much.)

I have to say, it doesn't feel 'scripted' to me, because allowing airspeed to increase by, say, 20 knots before rotation seems to dramatically reduce the need for right rudder as the nose comes up. Similarly in the 182, I've found that using the recommended 10° flap take-off setting also means less rudder input is required. Setting proper take-off trim in the 182 also helps, likely because it means less back stick deflection is needed in the sim.

The Comanche needs some right rudder during the roll then gently climbs straight with small corrections due to the wind. Same with the 182.

It's definitely not this simple with my set-up. I think part of the problem is that there are so many variables at play in terms of controller settings, that this force is likely experienced quite differently by some users. I quite like the fact that really accurate timely rudder control on rotation is needed to avoid a 'sloppy' take-off in these planes though, and to keep the nose pointed straight ahead, even without any wind.

For the OP, I'd definitely recommend turning all weather off completely if troubleshooting.

Cheers,
Nick

[AKar]

Yep.

I think I understand the effects that cause the behavior seen in the video somewhat well, that's actually precisely what makes me wonder: I can with little effort pull the nose up, hold her steadily there, making the plane light on its mains. But, holding the airplane there, at constant attitude, accelerating, at the moment the mains leave the ground (they should get progressively lighter as I accelerate at some definite angle of attack), the yaw kicks to the left. It happens, no matter how careful I try to be in holding the attitude, keeping the track and being progressive thorough the maneuver.

-Esa

[Nick - A2A]

Interesting observation. Perhaps if something is 'scripted' here, it's whatever stuff is buried in the Accu-Sim code to overcome the rather poor dynamic friction of FSX, i.e. the custom code which causes the tyres to 'grip the tarmac'. That's to say as soon as the mains leave the runway, perhaps this enhanced dynamic friction simply ceases to have an effect and it's not the yaw as such that's scripted.

If so (if the 'tyre grippyness' effect is either 1 or 0) this would probably explain the behaviour described. I'd guess that being able to simulate the dynamics of an aircraft being light on its mains may be a bit beyond the scope of the FDE here, though I'm just postulating.

Nick

[AKar]

Yeah, I wonder.

-Esa

[torque2]

I too have been plagued by this problem. It led me to uninstall this fine aircraft as 'unflyable'! But today I decided to try it again and discovered something. I disabled a 'dynamic friction lua' I have set to automatically load (through FSUIPC) whenever FSX starts. I have been using if for some time to reduce FSX's unrealistically high ground friction. I retried my takeoff, big improvement!! No longer does the 182 suddenly swerve to the left on liftoff. I'm guessing as soon as liftoff is achieved the lua stops working its magic and that affects the accusim flight dynamics of this aircraft.

Something to consider.

David
CYXE