Stationary Yawing

[Angelus2141 11]

Hi All,

         Long time since i been on the forums, how y'all doing. Just thought id check here before reporting a bug. It seems my old nemesis none controlled yawing is back. I encountered this in 1.11 with the wheel update when squad introduced friction and dampeners and such. Managed to find a work around at the time and then in 1.2 the issue wasn't there. Just updated to 1.3.0.1804 and it seems to be back. it might be because the craft was saved in 1.2 but thats something I still have to check.

 

It seems though the issue has come back. With my craft is on the runway and no control inputs the nose slides from left to right at random seemingly. I've tried my old fix and this doesnt seem to alleviate the problem. Ive tried all wheels on auto friction and full brakes. All wheels on friction override with max friction and max brakes. same again with standard braking force. At this point the only thing I can think to try is a full rebuild in 1.3. if you want to look at my craft you can find it here

 

https://kerbalx.com/Angelus2141/Kedillac-SSTA-Mk-II

 

thanks for your input in advance

Edited June 14, 2017 by Angelus2141
thanks

[Snark 12,990]

Moving to Gameplay Questions.

[bewing 2,624]

To fix the yawing problem using friction controls, you have to understand that passive stability comes from having lots of drag behind the CoM, and very low drag in front of the CoM. When you are talking about driving around on the ground, that means wheel friction. So you want the friction on the rear wheels to be high, and the friction on the front wheels to be low. So try setting the front wheel friction to .4 or less, and the rear wheel friction to be 1.5 or higher.

 

[Angelus2141 11]

thanks for the reply but ive tried high rear friction and low front friction. I set rear friction to 5 and front friction to 1 and it still slides side to side.

[bewing 2,624]

4 hours ago, Angelus2141 said:

thanks for the reply but ive tried high rear friction and low front friction. I set rear friction to 5 and front friction to 1 and it still slides side to side.

How far behind your CoM are your rear wheels?

And how far ahead of your CoM are your front wheels?

 

Edited June 15, 2017 by bewing

[OHara 482]

16 hours ago, Angelus2141 said:

With my craft is on the runway and no control inputs the nose slides from left to right at random seemingly.

Stationary? or on the takeoff roll ?  (You title did say stationary, but just being sure.)

I tried your craft from kerbalx just now.  

Stationary, in KSP 1.3, with brakes on it remains stationary for me.  I notice you set zero friction on the front wheels, which I though maybe would let them slide sideways, but I don't see it slide here.  With brakes off it starts to roll (at the expected 1.4km / 600km × 9.8m/s² = 1.4 m/s /minute from the flat runway on small-radius planet) but doesn't seem to slide.

On the takeoff roll with no input the wings took the weight off the rear wheels first, leaving just the front wheels pressing down (the 'wheelbarrowing' problem common to nosewheel aircraft if you forget to trim up for takeoff) and that rolling drag near the nose could make the plane unstable in yaw.  It was not too bad, though.    You might like to add yet another action group binding, to 'deploy' some or all of the canards when gear is down.  That will pull weight off the front wheels when you are on the ground.

Edited June 15, 2017 by OHara

[Angelus2141 11]

10 hours ago, OHara said:

Stationary? or on the takeoff roll ?  (You title did say stationary, but just being sure.)

I tried your craft from kerbalx just now.  

Stationary, in KSP 1.3, with brakes on it remains stationary for me.  I notice you set zero friction on the front wheels, which I though maybe would let them slide sideways, but I don't see it slide here.  With brakes off it starts to roll (at the expected 1.4km / 600km × 9.8m/s² = 1.4 m/s /minute from the flat runway on small-radius planet) but doesn't seem to slide.

On the takeoff roll with no input the wings took the weight off the rear wheels first, leaving just the front wheels pressing down (the 'wheelbarrowing' problem common to nosewheel aircraft if you forget to trim up for takeoff) and that rolling drag near the nose could make the plane unstable in yaw.  It was not too bad, though.    You might like to add yet another action group binding, to 'deploy' some or all of the canards when gear is down.  That will pull weight off the front wheels when you are on the ground.

interesting! yeah it was stationary. brakes on and yawing and sliding on the runway. maybe ill try redownloading and try again. ill also look into the canard thing. Thanks for the info

[Angelus2141 11]

ok its fixed but i use the term fixed reluctantly since the action need was rather simple. Heres the isntructions.

removed front wheel that came with save file

put new wheel on

move slightly forward.

 

its not just me right.. thats confusing ... not the instructions... just that it worked