Horizontal landing on Minmus.

[Othuyeg]

I have been attempting a horizontal landing without any retro burns (other than de-orbiting) on the frozen lakes of Minmus. Do you think it is possible? Maybe someone has even tried it and maybe even managed to do it? I love my space planes... Search turned out no reports of such madness so I shall post a new thread.

Discuss.

[Othuyeg]

Whoever moved the discussion, thank you. I noticed after posting that it was better suited here.

[Ralathon]

It should theoretically be possible, orbital velocity around minmus is slow enough for it. But I don't think you'll find a lake large enough to do it. The first time you hit the ground you're still moving at orbital velocity, so you'll just bounce back up into orbit. I doubt that you can lose enough velocity to friction during that brief contact, so the next time you hit the ground is on the other side of minmus or something (And this time at a less forgiving velocity).

[Jasmir]

It should theoretically be possible, orbital velocity around minmus is slow enough for it. But I don't think you'll find a lake large enough to do it. The first time you hit the ground you're still moving at orbital velocity, so you'll just bounce back up into orbit...

I think, the use of radial upwards firing rockets is a must have to get any friction.

[Javster]

There really is little point, because of the lack of any air...

[Cerberus738]

I've done a horizontal landing on the Mun.... first coupe attempts were a disaster. I ended up having to land backwards and fire the main engine on touchdown to slow down. Trying to brake just caused my plane to flip one side or the other and then the low gravity caused it to bounce away... Then boom lol. Velocity would be more forgiving on minmus but Jack of traction would probably be a big problem. You might need a braking engine on the front. It wouldn't need to be that big I don't think.

[Othuyeg]

I suppose a retroburn would have to be done once touchdown has been accomplished.

[arq]

It's difficult. I've tried something like 20 times with varying techniques. The bouncing is what kills you. I eventually gave up and now do the standard 'kill horizontal just above the ground, then do a vertical approach.' I flip back horizontal onto the main gear at the last moment, falling the last few meters unpowered. This does mean that I do a horizontal takeoff, though.

[cantab]

Manley's done it, of course:

[Tex]

Yes, it'll be very hard. I found out that Minmus rovers are a terrible idea when I burned to slowly and my rover bounced and, I kid you not, skipped a circumnavigation of Minmus. So yeah.

[Othuyeg]

Manley's done it, of course:

I am not too surprised. That man does a lot of great stuff... but he also did do a retro burn as expected. I am still wondering (and attempting to accomplish) if a pure landing is possible.

[Kasuha]

I tried it with my plane and I did not find a way how to land from orbit just on brakes. If I aim at plains to just clear terrain, put my periapsis so I just touch the surface and prepare brakes, I touchdown at about 200 m/s and the touch takes no more than 3 m/s off it after which I still safely fly back to space (orbital speed is about 150 m/s).

Even after I braked by engine to 100 m/s on touchdown and then switched off the engine, I was not able to stop before plains ended because the plane was just making too long jumps after each touch.

With braking engine ignited just at the moment of touchdown it looks like a horizontal landing, though.

Edit: looks like Manley did not do any better than I did.

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Edited March 20, 2014 by Kasuha

[Othuyeg]

I believe the key to this might be mass. You might need alot of mass to resist the bounce and stay on the ground for long enough to kill your speed.

[Cerberus738]

What about using rcs to translate downward as you brake? It would minimize bouncing and you could get more traction. More mass while landing means you have to launch more mass and that creates mute problems all their own. Rcs thrust could simulate more mass.

[MBobrik]

Try that on Tylo (ducks and runs)

[Blue]

It would be unnecessarily difficult, since the surface of Minmus has incredibly low gravity and its icy surface has reduced surface traction, making the necessary surface braking nearly impossible. It's simply better to just use a rocket engine burning from altitude.

Try that on Tylo (ducks and runs)

The fun part about that is not trying to have wheels that will accept punishment of contacting the surface at 7200kph, but due to uneven surfaces at that speed. A speedbump becomes a wall, and a mountain becomes a slightly larger wall.

[Othuyeg]

It would be unnecessarily difficult, since the surface of Minmus has incredibly low gravity and its icy surface has reduced surface traction, making the necessary surface braking nearly impossible. It's simply better to just use a rocket engine burning from altitude.

I don't think anyone who is thinking about doing this is doing it to make it easier for themselves.

It is more about is it possible.

[cantab]

I wonder which is more efficient though? A normal rocket landing, or a rolling landing using downforce engines and the brakes.

[Othuyeg]

IF it was possible to optimize the downforce so that you only use enough fuel to keep it on the ground until enough speed has been killed off, then I believe it would be more efficient to use brakes.

[SuperBigD60]

IF it was possible to optimize the downforce so that you only use enough fuel to keep it on the ground until enough speed has been killed off, then I believe it would be more efficient to use brakes.

I suspect that, at best, it'd cme out even, but skimming the ground and using a retroburn would likely be more efficient, I think. boosting parallel to gravity usually wastes a lot of fuel, in my experience.

[vger]

Is this 'really' even worth the trouble? Are you trying to save on fuel, or.... ?

[Jasmir]

I've done it today, and i have made a video from it:

http://youtu.be/6K980QPp1w4

(with downforce-pusher and wheelbrakes)

[TranquilTempest]

I've done horizontal landing on Minmus at about 50m/s, but brakes were quite ineffective. I suspect trying from more than 100m/s or so would run you out of lakebed.

[Othuyeg]

I've done it today, and i have made a video from it:

http://youtu.be/6K980QPp1w4

(with downforce-pusher and wheelbrakes)

I salute you good sir. That was very impressive.