the functional lithobraking challenge

[king of nowhere]

lithobraking. we all know it. the missed manuever, the impact, the explosions...

that's not the lithobraking i'm talking about. i learned the word on this forum, but i was then surprised that lithobraking is a genuinely available technique for slowing down during landing. of course, it entails surviving the crash. for example, the first mars rovers used to hit mars on inflatable airbags; that was lithobraking. the philae lander also lithobraked on comet churney-gerasimov, though in that case it was only moving at a few m/s.

but how far can you push the concept? So here's the challenge:  make a lander that survives the highest possible landing speed. To better elaborate

1) there is only one factor for ranking, which is speed relative to the ground at the moment of first touchdown. though a special mention will go to whoever will manage to make a lander that can actually save weight by lithobraking (i.e. you show that the heavy landing gear was lighter than the fuel needed for a normal rocket braking in the same conditions)

2) you can use your rockets as much as you want before touching the ground, you can even use the alt-f12 menu to get into the desired orbit. but after you touch the ground, use of any form of propulsion is forb idden

3) the vehicle will likely bounce a few times. surviving the first touchdown is not enough; the vehicle must eventually reach a full stop. in fact, in my experience, surviving the subsequent bumps is much harder than surviving the first.

4) the vehicle must not sustain any damage. Exception: damage that can be fixed by an engineer with a few repair kits is ok. damage that can be fixed with eva construction is not ok. POSSIBLE EXCEPTION: if enough people take part in this challenge and there is a request for it, I will add a category for "survived with damage", where it is allowed to lose some pieces along the way as long as the vehicle keeps working (to be determined on a case-by-case basis)

5) planets with atmospheres are forbidden. the purpose of the challenge is to lithobrake, air would be an unfair help.

6) to better document speed relative to the ground, it is suggested to record a video of your landing. be sure to document everything until you come to a full stop; as i mentioned, it is easy enough to survive the first impact, much harder to survive the subsequent ones, because you have no control over your trajectory

 

and that's it. i tried to land on minmus from orbit, it took a bit of trial and error but it could be achieved. Then i went for the next bigger body, Bop. that was much harder, in part because of the topography. But I eventually made it, after hitting the ground at 187.1 m/s. Next step would be trying on Ike, but I doubt it's possible. I could try on Minmus from a higher orbit, but for now I'm satisfied. Let's see if someone will do better

 

 

P.S. It is recommended to install some mod to ignore time warp limits. I didn't have one, and I had to actually wait at 1x through all those suborbital jumps. It took 50 minutes. it's a better experience if you can time-skip the boring parts

Top scores

1) @dnbattley 560 m/s circa, on Mun.

2) @king of nowhere 187.1 m/s, on Bop.

3) @xendelaar 160 m/s circa (no exact value), on Minmus. He also made a whole propeller-free mining facility, where he throws fuel tanks in orbit with a giant slingshot and recovers them by lithobraking. He gets the special mention for having a system that's actually cheaper than proper rocket-braking

Edited June 5, 2021 by king of nowhere

[Wizard Kerbal]

I did 89 m/s on a Rhino and 5 meter medium-sized tank for a giant rover, but I didn’t record it.

[dnbattley]

It was on an old version, given this video is 3 years old, but:

https://youtu.be/QXst9xp9GJY

[xendelaar]

Very nice challenge!

I made a craft land on minmus at  ~150 m/s . you can see the landing around 2:40 in the video below.

I didn't show any readings so my entry is not valid, but I still like to show you what i've done and (bump this thread a bit).