Does anyone have an idea of why all of my taildragger aircraft go out of control immediately after the tail wheel lifts off of the runway? None of my tricycle gear planes do this while every taildragger does? This happens at every airport I have tried. I know that ground steering taildraggers is different, but this is uncontrolled, violent behavior. Thanks for any help and advice!!
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All propeller-powered airplanes are subject to turning tendencies produced by the engine. Most western single-engine aircraft have a propeller that spins clockwise when viewed from the cockpit, which results in three left-turning tendencies. These are spiraling slipstream, torque, and p-factor (or asymmetric blade effect).
There is a fourth turning tendency that adds to those left-turning tendencies with tailwheel aircraft, specifically. This is called gyroscopic precession and happens at the moment the tail rises.
Additionally, all aircraft can be influenced by weathervaning, where they try to align with the relative wind. Because of the placement of the gear more forward and the long arm to the tail of the aircraft, tailwheel aircraft are quite a bit more susceptible to turning into the relative wind during the ground roll. This effect is fairly overblown in all aircraft in the sim, even tricycle gear. Real-world, they’re a lot more stable (though excursions are still common enough that the term “more right rudder” is basically a CFI’s mantra). The faster you go, the control surfaces become more effective as well as the relative forward motion begins to decrease the proportion of any crosswind.
Further, any of these effects can be exacerbated by incorrect pilot inputs, leading to pilot-induced oscillations. In real life, we pretty much use frequent, small corrections to “dance” on the rudders during the takeoff roll to stay aligned. The increasing aerodynamic pressure on the rudder as we increase speed down the runway acts to dampen our inputs (stiffens the pedals) so we aren’t quite as likely to overcontrol as we are with tiny or lightweight game controllers. The dance, as it were, is also aided by the seat of your pants feel and your peripheral and far-field vision.
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Also, something that could help us differentiate and diagnose your specific problem is to let us know the type of aircraft, your control setup, and the wind conditions (and runway heading) when you’re encountering the problem.
On top of the forces mentioned above by CharlieFox00 that occur both in the sim and real life, I blame, at least in part, the steerable tailwheel that is the default and the lack of free-castering tailwheels.
With a free castering tailwheel, the forces that would cause the aircraft to swerve (with exception to gyroscopic precession) would already be taking place before the tail rises and the pilot would be counteracting with the rudder. Once the tail rises, rudder is already being used to counteract these forces.
In MSFS, the steerable tailwheel locks the tail straight with a lack of rudder input. Even if you anticipate, say, a crosswind, you cannot begin proactively countering it because the steerable tailwheel will steer the aircraft off course. You are forced to wait and time your response awkwardly once the tail comes up.
Add the gyroscopic precession in when the prop rotates forward as the tail comes up, and you’re in for quite a ride. The problem is less severe with aircraft that have a locking tailwheel, but still exaggerated due to the strange wheel friction issues (lack of stability as mentioned above) in the sim.
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Learn the rudder pedal dance. Welcome to tailwheel life. I suspect it’s p factor and weather vaning coupled with standing on the rudder pedals. It took me 100+ hrs of practice but these days my tailwheel skills are pretty descent in the sim.
This is the reason why it happens.
Whole video is a nice tutorial about tailwheelers indeed.
Cheers
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The problem is that MSFS doesn’t well simulate (or rather not at all) propwash over the rudder (and elevator). In reality you can control an SEP taildragger with the rudder only by the propwash. In MSFS that’s not possible and you need to keep the tailwheel on the ground as long as possible for directional control which would be totally wrong and dangerous IRL.
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FSRealistic has a setting for Prop Wash.
I normally leave it on, but in one of my planes (sorry, I don’t remember which) I found out that enabling it locked out the rudder. It took me a while to troubleshoot that problem! 
Yeah I haven’t had really good experiences with FSR and the propwash. It fakes the whole thing and moves the plane around weirdly, the sim would need it as a default implementation. Asobo started it with their CFD stuff but after a great display on social media they stopped working on it midway. Accusim nails it, at least in the Comanche for now. But knowing it from P3D it will work just as well in taildraggers. It’s a real pity that Asobo or MS gives so litte attention to the flight physics.
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us auto rudder until you get a feel for how to control the tail with the wheel off of the ground. It helped me a lot.
…Yeah, considering it IS supposed to be a flight sim.
I see Austin has just issued a video where the first thing he said was that the flight model was EVERYTHING.
Hey Jorg or whoever reads this, c’mon man, get with it.
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Austin? Xplane?
In that case, yep, XP really has a great focus on actual flight physics. I don’t even mean specific aircraft characteristics but real and plain physics. What is an airplane, how and why does it fly, what do control inputs do with that wing, what are the consequences of aileron or elevator input.. XP really gets this done beautifully. MSFS could do it, too, with how they simulate actual airmass. The sim could do so much more. Taildraggers are the best example that MSFS stopped development somewhere in the middle, nothing was really completed.
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You can say that again!
Indeed the same FSX solution was used on MSFS (based on wheels adhesion). Seaplanes are another example of a FSX direct port over. They land on seabed not in water and they just have less adhesion there than on regular terrain. Waves do not move them at all for instance.
Cheers
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I’ve done enough sim aircraft design work to make an educated guess that part of the problem is that ground contact points are just that - points. Whereas in reality, each tire contacts a surface in a much larger two-dimensional plane, and those dimensions change based on tire pressure, weight on the wheels, tread, and even angle. That’s before we get into surface friction, contamination, braking, etc.
In this regard, the sim can and probably should take cues from racing sims because wheel physics are really just as important as air physics in the real world, at least for the amount of time they’re in contact with the ground. If they get that right, it might create a world in which airplanes behave properly on the ground, allowing for skidding, hydroplaning, and better taxiing, weathervaning, and ground loop behavior, amongst others.
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I’ll just leave this here. Strange to see the control surfaces flapping about here like a screen door in a hurricane.
No idea what you do there 
What I meant above was not that XP was perfect. Its approach to how aircraft behave is right though. Control surfaces react with the air stream mostly as they should. I hven’t used XP for several years so no idea what’s going on here ^^ My last time in XP was 11.3 or so.
On a side note… I always thought XP looked better than P3D xD
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Not being a pilot, I didn’t either, until someone explained it to me.
The aircraft is in a moving airmass, and yet the rudder, and elevator, are moving about as if the planes body is fixed, like in a wind tunnel. The plane, and its control surfaces should be moved about at the same speed, so you wouldn’t see them flapping about like that.
This was an early release so perhaps newer ones have been updated.