Lithobraking Calculation Question

[The Joker]

So, if anyone here has attempted lithobraking (though I'm sure most of us have on accident ), they know that while you have pieces that can survive incredibly high impact velocities (namely the structural pylon) but the problem is that in that time frame the pylon itself has stopped but the rest of the craft has not, so the craft is destroyed anyway.

Today, on the KSP subreddit, I saw a post of a lithobraking on Kerbin using the structural pylon. To get around this, he placed the pylons on top of each other to "cushion" the fall. Each pylon meant a drop in force. What I want to know is if this drop of force between parts can actually be calculated mathematically to be used to plan lithobrakers in the future.

[Brainlord Mesomorph]

I built a lander once with small extra fuel tanks the protruded past the engine cone. In a hard landing if the landing struts broke, these fuel tanks would hit first, explode and protect the engine.

I called it a crumple zone.

re: the OP:

You could run experiments, dropping things from gantries at the KSC. I found that combinations of girders and struts can create "springy" parts that support a lot of weight,

[SkyRender]

I actually built a rover once with a cage of girders around it as part of my effort to make that rover more capable of surviving flips. (It also had a pair of mini reaction wheels for flipping itself over.) The end result was a rover that was practically indestructible. As long as it didn't land on its wheels (which a rover rarely does when it flips), it could survive tumbles at 60m/s just fine.

The main point of this is, if you want to make a craft that can survive impacts, wrap it in the thick girder segments you start with in Career mode.

[thadisjones]

I've used the empty fuel tank crumple-zone technique a few times when testing landers and not QUITE knowing if I'd packed enough parachutes to come down safely on Kerbin.

The structural pylon thing though- they really shouldn't be that impact-resistant. They are both floppy and explosive, which doesn't intuitively suggest they'd be great items for playing bumper cars with planets. When you factor cost and mass, a single pylon is roughly as heavy and a lot more expensive than a single radial parachute, so making extensive spring-leggings out of pylons is pretty much a losing factor in any direction.

[Norpo]

I once made a capsule, and just stuck a crapton of Vernor engines to it.

Long story short, vernor engines are weightless, and have an impact rating of 40 m/s. Cue crashing into the mun at 200 m/s with the 3 Kerbal Pod and surviving.

If you do it right, you can save quite a bit of delta-v.

[dsmiley53]

I believe Danny2462 did something like this, and broke the lithosphere.

[Skorpychan]

Landing legs are great for this. Otherwise, engines, fuel tanks, and anything between the crew and the ground is emergency braking.

[Vanamonde]

How-to sort of question moved to the how-to sort of sub-forum. Carry on.