Author Topic: Landing Lunar Starship nose down  (Read 5197 times)

Offline zodiacchris

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Re: Landing Lunar Starship nose down
« Reply #20 on: 11/24/2023 05:19 am »
Thatís a great idea, letís call it Steagle! The Steagle approach definitely beats the headstand landingÖ😎

Offline kkattula

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Re: Landing Lunar Starship nose down
« Reply #21 on: 11/24/2023 06:09 am »
One disadvantage of the nose down concept, with landing thrusters pointing in the opposite direction of the main engines, is having both lit at the same time wastes propellant and maybe impractical due to settling.

This means you likely have to commit to shutting down one set before starting up the other, on both descent and ascent. 

With the high-mount ring of landing engines, or even side-mount thrusters for a horizontal lander, you can easily start up the second set while the first is still running, and if they won't start, abort to orbit if descending, or abort back to the surface if ascending.

Offline kkattula

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Re: Landing Lunar Starship nose down
« Reply #22 on: 11/24/2023 06:19 am »
It seems to me that if one were going for the nose down approach, permanent legs and landing engines could be attached after the vehicle is in orbit. A vehicle that will never again deal with atmosphere shouldn't have to worry about a sleek profile. It would eliminate one failure profile of things not extending during the landing maneuvers.

No need to wait for landing to deploy them.  Once the ship is in LEO, the legs could be unstowed from a launch position, and permanently locked in place.  As long as they don't interfere with required docking. 


Offline mikelepage

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Re: Landing Lunar Starship nose down
« Reply #23 on: 11/24/2023 10:59 am »
If you're not so volumetrically constrained by the engines and prop tankage, you can afford to make the legs quite a lot bigger.
Quick and dirty animation of the concept attached.

Why is the nose so far off the surface? Bring it as close to the ground as you can. Get rid of the elevator entirely.

Hell, if the engines are way-up-the-other-end, why not use the nose itself as the primary landing leg. Then the outer legs are purely for stabilisation rather than supporting the entire mass, hence their deployment systems can be reduced in size/mass.

And given the way you've folded out the landing legs, those outer legs can also serve as ramps/stairs, leading to openings in the sides of the nose to the unpressurised cargo deck. (Hmmm, you could have two longer, two shorter legs, leading to two cargo decks. Increasing available cargo volume.)


I mean, if you're going to do this, go all in.

To be honest I didn't even think of using the nose as the primary landing structure. That's a much better idea, thanks for actually working the concept. I figure you could eject a small nose cone and use that entire payload space for some kind of shock absorber structure.

I've tried mocking up an animation of nose-as-landing-leg, with an unpressurised cargo area which is basically at ground level (actually about a meter up). I went with three legs here in order to maximise the width of the openings (the max dimensions for a habitat module here would be 3.5m diameter, 5-ish meter height, assuming you arrange the pistons better than I've done here). I've run out of time tonight to try to implement something with stairs, but I'm not even sure stairs are the right choice. With a 25m stance width, the stairs would have to be pretty steep.
« Last Edit: 11/24/2023 11:01 am by mikelepage »

Offline mikelepage

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Re: Landing Lunar Starship nose down
« Reply #24 on: 11/24/2023 11:11 am »
One disadvantage of the nose down concept, with landing thrusters pointing in the opposite direction of the main engines, is having both lit at the same time wastes propellant and maybe impractical due to settling.

This means you likely have to commit to shutting down one set before starting up the other, on both descent and ascent. 

With the high-mount ring of landing engines, or even side-mount thrusters for a horizontal lander, you can easily start up the second set while the first is still running, and if they won't start, abort to orbit if descending, or abort back to the surface if ascending.

Yes, the abort modes are the thing that seems most problematic to me. But having said that, the flip itself can be pretty leisurely in lunar gravity. I played with the math upthread, and found the ship can decelerate to a near halt at a staging altitude of say 12 km, commence the flip, and if there are any issues starting landing engines, one can let the flip turn into a 270, and proceed to abort to orbit. The decision to make a final approach for landing or not isn't a hurried one.

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