Plane keeps on turning even with no input

[Krishnan Kerman]

Hello. I was bored and decided to build an ssto. I built it, and when I got on the runway and started takeoff, the plane yawwed hardd to the left even with no input.

I tried and tried fixing it, but after 3 hours, it was still a problem.

Please help me!!

Is there a way to fix the physics engine itself? I think a mod messed up stuff, and I don't know how to.

Thanks!

[Lanley Kerman]

Tried using SAS?

[James Kerman]

2 hours ago, Krishnan Kerman said:

the plane yawwed hardd to the left even with no input.

There can be many reasons for this behaviour so in this case a pic would really help. Some quick things to try would be to increase the spring/dampers of the landing gear (you need to enable advanced tweekables in the settings menu) or try larger gear. Another possibility is that you are getting asymmetrical thrust on launch because you don't have enough air intakes and so only one engine is firing.

[bewing]

Planes veering left on the runway is a very common problem. Unfortunately, there are quite a few engineering problems that cause the same effect on the runway. It is common enough that it's in the FAQ on this forum. The most common and easiest solution is to set the friction on the front landing gear to "manual" and then reduce it to .5 or less. You can reduce it all the way to zero if you feel like it..

[RoninFrog]

One other possibility I see is COL and COM problems, a real classic.  If the plane is aerodynamically stable horizontally but not vertically, it will try to turn sharply. Try putting a bigger tail fin on the back of the plane.

Edited May 5, 2020 by RoninFrog

[Rocketology]

A large part of the cause is by over stressing the nose gear. If you position the main gear just behind the CoM and ensuring the craft sits level on the runway, it will help keep the bulk of the mass on the main gear. Also make sure the gear is square, meaning aligned properly to the fuselage, it's easy sometimes to mount the gear at unintended angle, this can lead to over stressing as well. And finally, speed; it is possible to overspeed the landing gear, and the curve of this rises sharply the more mass on the gear. 

Here's a guide that I use for landing gear placement that is used for IRL aircraft: