Plane powersliding when braking on runway

[archnem]

Hi all,

Got a problem.  I have a simple plane/shuttle I use in early career for fulfilling basic tourist contracts.  It works fine, but when I land it, I hit the brakes and it starts to slow down just fine, then suddenly will veer one way or the other and do a "power slide" turning a full 360 sometimes before stopping - like something straight out of an action movie.  Of course sometimes this also involves wings or engines slamming into the ground, but Jeb don't care, he likes style points apparently.

I added a couple of drogue chutes to the back of the plane to stop this from happening, but as this is a tier 1 plane/SPH, every part counts, and I'd rather have a couple of solar panels instead.  I've tried altering my gear placement, setting the rear gear to 200 drag and the front to 50, disabling steering on the rear or both gears, nothing seems to help.  Anybody else have this issue and found a way to fix it?

Here's a link to a few pictures, any help would be appreciated.

http://imgur.com/a/4Y55u

[DD_bwest]

i know very little about planes as i hardly ever use them, so im probably WAY off..

maybe during the braking on landing it puts more force on the front gear, making the brakes on the front alot more effective and the rear brakes less so, which causes the back to want to whip around front?

maybe try moving your rear landing gear closer to the com

[bewing]

I think DD_bwest has the basis of the problem correct. You lowered the friction at the front end (which is helpful) ... but did you reduce the braking force from the front wheels? (I assume that you already increased the brakes on the back?)

I think you may have your wheels splayed a bit too much, also. They only work properly over a limited range of contact angles with the ground.

 

[HvP]

As bewing said, having your wheels angled outward doesn't work as well in KSP. It's better to drag the attachment base out from the fuselage and rotate them so they point straight down. The easiest way to do this is set mirror symmetry to 2 and place your gear on the midline under the craft and then use the translate arrows to drag the bases outwards. The wider you can get them the better. You might get away with placing them under the engine nacelles if your center of mass is far enough forward. If not, consider one at the nose, one at the back (but not too far back) and one on each engine nacelle.

I don't think you need two landing gear at the nose of the craft. One in the center of the nose should be fine.

If you enable Advanced Tweakables from the settings menu you will find an option to set the landing gears' Friction Control. I've found that increasing the friction on the rear set to about 2.5 or 3 really helps a lot.

[archnem]

Ive tried straightening the gear w no luck, I'll mess w friction control and use a single nose gear and report the results.

[archnem]

OK after playing with the numbers and placement I've found a solution.  Friction control didn't really help much, and it turns out I can't have a single nose gear, the plane is too wide and just tips over.  However these two things worked:

1) I actually had to move the nose gear back.  I had been so focused on the rear wheels, I hadn't tried this.  This helped alot.

2) I had to increase the brake strength on both sets of gears. I ended up setting the nose gears at 150 and the rear wheels at 200.

3) I straightened the wheels for aesthetics, but this actually didn't do much - it worked just as well with splayed gears.

Thanks for your help guys! Got me thinking outside my little box.

 

[HvP]

11 minutes ago, archnem said:

OK after playing with the numbers and placement I've found a solution.  Friction control didn't really help much, and it turns out I can't have a single nose gear, the plane is too wide and just tips over.  However these two things worked:

1) I actually had to move the nose gear back.  I had been so focused on the rear wheels, I hadn't tried this.  This helped alot.

2) I had to increase the brake strength on both sets of gears. I ended up setting the nose gears at 150 and the rear wheels at 200.

3) I straightened the wheels for aesthetics, but this actually didn't do much - it worked just as well with splayed gears.

Thanks for your help guys! Got me thinking outside my little box.

 

Glad you found a solution that works for you. Planes are tricky.

[foamyesque]

Ultimately what causes the 360s is excess drag on the front gear. That can have a variety of causes; aerodynamics and braking are two big ones.

There's a few other things you might want to consider: The rear wheels should be much closer to the CoM (and you do only need one nose gear, and it can be further back than in your picture). That will let you take off much easier. Also, the plane will be much more controllable, and sturdier, if your engine nacelles are affixed to the fuselage instead of way out on the wingtips. You can then put your rear gear on the nacelles, which will give you a nice wide footprint for ground stability. Turn off, or at least way down, any brakes in the nose gear.
 

[GoSlash27]

Nose gear should never have brakes.

Best,
-Slashy