Crash landing

[Xannari Ferrows]

Here's the issue.

You're approaching Moho, textures and colliders are constantly being loaded and rescaled. 15.2 square kilometers of meshes.

Because of how the game manages all of this stuff at once, the physics engine only works on every frame instead of accounting for the differences. This means that a lithobreaking at absurd speeds could make you pass through one of the colliders, and you will explode immediately.

[Starhawk]

It's probably going to take quite a bit of trial and error to find an optimal solution.

After all, I'm not sure this has ever been really tried in KSP. It's certainly not the type of engineering I have any experience with.

I switched to the Mun for impact testing yesterday because the air kept getting in the way.

If my simple rig could withstand 215 m/s I think 600-1000 is probably achievable, but I'm really just guessing.

Unfortunately, I have no more KSP time today, or I would do some more tests myself.

Once again, happy crashings!

[Foxster]

Yup. Looking like a game refresh rate thing problem. One second I'm drifting into Moho at 600m/s (a modest 4.8 million MPH) and the next it goes all kabloooy. Boo!

[Norpo]

I've done this with vernor engines before (weightless, 45 m/s tolerance), and it's defenitely a physics calculation rate issue.

I think that's what the physics delta-time option does, but don't take my word for it.

[Mad Rocket Scientist]

The structural pylon has a impact resistance of 999m/s.

[Foxster]

The structural pylon has a impact resistance of 999m/s.

Didn't I mention that in the first post?

[Mad Rocket Scientist]

Didn't I mention that in the first post?

Oops, missed that!

[sisyphean]

i have several times accidentally survive 150-200m/s crashes completely intact on the moon using the baby lander legs, i figured it was a physics glitch whenever it happened because the only damage my lander would take was the legs locking up and not retracting or being springy, but maybe it had something to do with low vertical velocity or something (i was flying a shallow descent path due to low deltaV allowance).

like i say though the 3 or 4 times it happened were accidental and im not sure if i still have the craft file to retest it.

[Foxster]

i have several times accidentally survive 150-200m/s crashes completely intact on the moon using the baby lander legs, i figured it was a physics glitch whenever it happened because the only damage my lander would take was the legs locking up and not retracting or being springy, but maybe it had something to do with low vertical velocity or something (i was flying a shallow descent path due to low deltaV allowance).

like i say though the 3 or 4 times it happened were accidental and im not sure if i still have the craft file to retest it.

There's maybe something in that. Especially if its all about glitchy stuff. If you can come in shallow then you can perhaps stay above the surface between 'frames'.

[Windspren]

This might actually be a viable option for Eve because of high drag there. It might cut some delta-v out of decents.

[Foxster]

This might actually be a viable option for Eve because of high drag there. It might cut some delta-v out of decents.

If you don't mind the part count it does work fine. I de-orbited the craft in the screenshot above over Eve, decoupled the engine and let it land on its own. It landed fine with just a few broken Cubics, as intended. Edited April 3, 2015 by Foxster

[Windspren]

If you don't mind the part count it does work fine. I de-orbited the craft in the screenshot above over Eve, decoupled the engine and let it land on its own. It landed fine with just a few broken Cubics, as intended.

Try getting a Eve acent stage down there.

[MarvinKitFox]

Umm, looking for more like 30,000m/s . Or am I being a tad optimistic?

Sure, no problem.

Just build a zig-zag crumple zone of structural members, deep enough to take the impact.

For 30000m/s, you need a crumple zone of about 120km depth.

This may lead to some slight inefficiencies in your ship design.

For a ship to survive a Kerbin re-entry with no propulsion, no lifting surfaces and no parachutes, you need about 4-5 layers of structural members.

I've managed to land a ship on the Mun from very low orbit. (impact ~ 560m/s), using some 50-60 layers of cubic octagonal mesh. It needed a LOT of luck though, as I could not afford to build the ideal spherical protective shell.

I *think* the needed crumple zone grows as the square of velocity (thus with kinetic energy).

if this holds true, 30000m/s would need 2900 times as much shock-absorber as the above 50-60 cubics...

Edited April 4, 2015 by MarvinKitFox