Challenge Safe Lithobraking

[MaverickSawyer]

Okay, there's the old joke about performing a lithobraking. I have done a few myself. :lol: However, I had a revelation: you can use it as a legitimate strategy to stop on the Moon, or any other airless body that is round. Just land slowly on the surface of the planet by placing the periapsis at just lower than the resting altitude of the craft. Can anyone make this work?

 

[Pipcard]

The hull would be damaged beyond repair, though.

 

[MaverickSawyer]

Who said anything about a gear up landing?

 

[mojoey]

Who said anything about a gear up landing?

challengeaccepted.jpg

 

[Pipcard]

Who said anything about a gear up landing?

Still, you can't just glide onto the surface (vertical speed of negative 1-5 m/s).

Is this for landing at the Moon Airbace?

 

[MaverickSawyer]

:facepalm: gear down on XR2, wheels contact surface, brakes engage, dropping apoapsis until below the surface. Continue until velocity reaches zero.
and as for Airbace ops: :shifty: maaaaybe.

 

[Napalm42]

You cant land at the airbace, because the OP is talking about landing on the surface, not the serface xD

 

[Pipcard]

Lithobraking from what speed, anyway?

 

[PhantomCruiser]

Mmmm, there's been a lot talk if previous threads about runways on the moon (and other airless bodies with low g). It can be done in Orbiter, sure. But in real life the surface would have to be prepared ahead of time.

I think the most plausable example in Orbiter is Greg Burch's Heinlein base, there are six standard landing pads (which I use for Dg style craft), and a large clear area that I use to eyeball landings with the Vanguard, and DGEX (never dropped and Arrow in there, yet). That large clear area would allow for a bit of forward roll on touchdown.

But a 15,000 ft runway on the moon? I can't see the logic in it. But then again, I'd be the poor sod who'd be tasked with replacing the wheelbrakes, tire/wheel ass'ys and shock struts for the hotdog pilot who ripped the gear off his spacecraft.


Next time my wife drives off the road into a ditch I'm going to use the lithobraking term and see if I get a response. More likely a blank stare... Or slugged. I'd bet a dollar that my kid will bust a gut laughing though.

 

[Linguofreak]

I've done a surface-run launch into lunar orbit in the XR-5 before. Not sure if I've ever done the opposite and landed from orbit.

I've also done some very close surface skimming in the Shuttle A.

 

[Sky Captain]

Better idea would be to do a lithocapture, it would certainly save tons of rocket fuel:lol:

 

[Urwumpe]

I wouldn't even try lithobraking on anything bigger than an asteroid, even if they discovered a planet made of soft pillows.

From 2500 m/s upwards, even a spiderweb in your path could cause serious damage.

 

[Chub777]

Just tried this in Orbiter with an XR2. With a perapsis of -0.20 metres (that's about 2/3 of a foot, for all you imperial people), I figured that this would do.

4 km left.

10 metres.

4 metres.

1 foot.

Touchdown!

The XR2 looses control and in my attempt to regain it, the XR2 flies up without any speed lost. Note that I didn't use a joystick and therefore didn't apply breaks facepalm.

EDIT: Tried with a joystick. Breaks don't have enough power on their own. So I declare this...

...well for me it is. Someone else give this a shot.

 

[jedidia]

Those would have to be some impressive breaks to slow you down from 2000 m/s... And some impressive tires. And some impressive runway. :shifty:

Still, doing this is one hell of an adrenaline kick! Let's open a moon-diving contest: Who manages to touch ground at the highest velocity wins. Earth-Moon direct returns with touchdown get free beer!

 

[Urwumpe]

Maybe you can use abrasive landing gear for that. <.<

 

[n122vu]

Maybe equip the craft with some type of wheel skis?

And use retro engines in place of thrust reversers - Is it even possible to come in on the moon for an off-runway type landing at a speed these would work?

 

[Spacethingy]

How's about a giant magnet thing on the ground? OK, so hitting it just right would be nigh on impossible, but it would avoid any physical contact. Kind of a railgun in reverse?

 

[Napalm42]

How's about a giant magnet thing on the ground? OK, so hitting it just right would be nigh on impossible, but it would avoid any physical contact. Kind of a railgun in reverse?

Everything electronic would need to be shielded, else everything would go bonkers from the charge.

 

[Urwumpe]

Everything electronic would need to be shielded, else everything would go bonkers from the charge.

Not really, that can be prevented by proper grounding of the spacecraft electronics (The magnetic field strength inside the hull is rather small, most action happens in the outer millimeters of the hull). The problem is rather preventing that the hull gets damaged by arcing.

 

[Chub777]

Those would have to be some impressive breaks to slow you down from 2000 m/s... And some impressive tires.

Impressive breaks and tires you say?

I don't think this is possible unless you turn your craft 180 degrees and burn the mains.