rover drop - brakes

[technion]

Hi,

Just trying to work out if this is my imagination/fluke/etc.

I'm testing the deployment of a rover on kerbin. It seems if I drop it from ~50m, it can survive the drop UNLESS THE BRAKES ARE ON, which cause it to explode.

[Ravenchant]

Are you dropping it from a hover? Unless its horizontal speed is near zero on impact, it may flip over because of the brakes...or explode. That works too.

[technion]

Are you dropping it from a hover? Unless its horizontal speed is near zero on impact, it may flip over because of the brakes...or explode. That works too.

It's being dropped from a lander that's parachuting down vertically. The rover has two separatrons to push it forward so I don't then land on it.

Without brakes, it lands and drives off. With them, it doesn't flip. But it does explode.

[Ahmed]

Can you tell us a touchdown speed? Maybe your rover is very heavy?

[psyper]

I think it might be the way the physics work. I'm no expert in this but it could be that the rovers forward momentum plus its downward momentum is above the speed needed for the wheels to take its impact which is why its exploding. When the breaks are off then the forward momentum isn't being stopped so isn't being calculated in the impact.

[Kasuha]

Maybe if brakes are on the suspension is locked, too?

[Claw]

I think it might be the way the physics work. I'm no expert in this but it could be that the rovers forward momentum plus its downward momentum is above the speed needed for the wheels to take its impact which is why its exploding. When the breaks are off then the forward momentum isn't being stopped so isn't being calculated in the impact.

This seems likely to me. If you say it drives off on its own after hitting the ground, then it sounds like there is a lot of force that is being sent into the wheels on landing (especially with sepratrons). If the brakes are locked, it might be too much for them to take, but just shy of causing catastrophy without them.

You can try testing your rover by itself, without the touchdown. Launch it, lock the brakes and activate sepratrons. It'll probably rip the gear off, but I don't know.

You can also try turning on brakes after you hit the ground. If you're doing this landing with two ships, you can hop between the two of them. Have a probe core on the rover (or a kerbal), switch to it right before/after it touches down and activate the brakes after the sepratrons are done. Then you can switch craft again while it stops itself. (Watch out for going beyond 2.5km from your ship in flight.)

You can switch craft with the bracket keys.

[Skorpychan]

I hate to ask, but if you're firing it forwards with sepratrons, how do you plan on getting to it after you land?