this spaceplane is not going straight

[king of nowhere]

I already have a decent experience running spaceplanes, so i was completely baffled when my latest attempt, which is a fairly simple design, failed.

It pulls to the right, and as it accelerates it tend to go in circles, eventually capsizing. and i can't figure out why that is. the plane is symmetric, i even tried to remove the rover arm (the only part i see that may be causing the problem) but no difference. i assumed something was wrong with the propellers, but i tried to shut them down and close the cargo bay, and put a rapier engine at the back to give a uniform push, but still it pulls to the right, so it's not the propellers. I'm baffled

[Guest]

It's hard to guess without a craft file. If you'll post that somewhere (e.g. https://kerbalx.com/) I'll be happy to take a look.

[bewing]

Are you sure it's to the right? They almost always pull to the left.

In any case, the problem of 'veering' is so common with planes that it's on the FAQ in this forum. There are many possible causes that all have the same symptom, but as far as I'm concerned, the most common issue and fix is something I call "ground drag". To achieve passive directional stability, you want low drag at the front of your vehicle, and high drag at the back -- no matter whether we are talking about rockets in the atmosphere, or cars on the ground. The most likely problem is that your front landing gear has too much friction with the ground. The fix is to change the friction on your front gear to "manual" and then reduce the value to .5 or less.

 

[king of nowhere]

14 minutes ago, bewing said:

Are you sure it's to the right? They almost always pull to the left.

In any case, the problem of 'veering' is so common with planes that it's on the FAQ in this forum. There are many possible causes that all have the same symptom, but as far as I'm concerned, the most common issue and fix is something I call "ground drag". To achieve passive directional stability, you want low drag at the front of your vehicle, and high drag at the back -- no matter whether we are talking about rockets in the atmosphere, or cars on the ground. The most likely problem is that your front landing gear has too much friction with the ground. The fix is to change the friction on your front gear to "manual" and then reduce the value to .5 or less.

 

it worked, thanks

[Klapaucius]

@bewing's suggestion is spot on. Also, did your remember to disable the steering on the rear wheels?

Edited November 1, 2020 by Klapaucius

[king of nowhere]

7 hours ago, Klapaucius said:

@bewing's suggestion is spot on. Also, did your remember to disable the steering on the rear wheels?

didn't knew i was supposed to

[bewing]

"Supposed" is too strong a word. Sometimes it helps a bit. But sometimes it's fun to have a plane with a tighter turning radius when taxiing.