Recover wreck from surface of minmus

[Pinchy]

I rejected this contract because I couldn't actually work out how I could fulfil it. Can't remember the exact wording but along the lines of recover a wreck from the surface of minmus. The obvious answer to me was to use a Klaw but then this is ridiculous as there is no way I could "dock" with it on the surface and reverse engines and lift it back into Orbit.

I potentially thought about using KIS and attaching THUD engines to the side and then decided there was no way to attach a fueltank - so conclusion was that it was impossible and I rejected the mission.

Wonder if anyone else has had a similar mission and how they went about completing it?

[Grumman]

I've done this before - not for a contract but because of a bug.

What I did is build a regular sort of lander with a claw on the bottom, and simply landed right on top of the rover I was trying to recover with the claw armed, then flew away with it.

[Geschosskopf]

Well, 1st you need to know what part is being used for the wreckage so you can then design a ship around that. And once you get within a couple hundred meters of it during the rescue, you can control the wreckage so can rotate it to the desired orientation (this is Minmus, after all).

Anyway, to actually grab the ship, you might consider building a lander with the Klaw facing down under a small central body that has radially mounted engines spaced wide enough for the target to fit between them, and tall enough for the central body to be slightly above the wreckage when the landing legs are down. Then the mission would go like this:

1. Land near the wreckage.

2. Switch to the wreckage and use its torque to put it in the desired orientation.

3. Switch back to the lander and use RCS to "helicopter" it over the wreckage and land again with the wreckage below the Klaw (this is Minmus, after all).

4. Arm the Klaw and retract the landing legs, causing the Klaw to come down into contact with the wreckage.

5. Fly back to Kerbin.

[Pinchy]

how did you have engine thrust with the klaw on the bottom - assume you didn't have a single engine lander - kind of like a trio of engines and the klaw in the middle so your COM when you picked up the wreck was correct?

[Harry Rhodan]

I potentially thought about using KIS

How about using a KAS winch to pull it up?

[Pinchy]

Ok makes sense Geschosskopf - didn't consider putting the klaw on the bottom.

[Reactordrone]

I picked a cockpit up from the Mun using this contraption,

Landed nearby and then drove to the pod using a couple of twitch engines for surface propulsion.

[Geschosskopf]

how did you have engine thrust with the klaw on the bottom - assume you didn't have a single engine lander - kind of like a trio of engines and the klaw in the middle so your COM when you picked up the wreck was correct?

This is why you need to know what the wreckage is before you go there, so you can design the lander to fit around it and have enought TWR (probably not an issue on Minmus) and dV to get back home carrying the wreckage. Either that or just build something totally over-engineered (but still costing less than the contract pays).

CoM placement only matters 1) during launch and 2) during docking. Otherwise, as long as it's in line with your thrust, no problem. The only issue you face here is the latter, and you'll just have to eyeball that. But Minmus has such low gravity that you can "walk" landers around on it via torque and RCS, so you can use that for fine adjustment before dropping the Klaw on it.

[Sharpy]

Using the torque with the wreckage may be impossible nowadays: they always come devoid of EC and mono; empty. Although you can "dock" at any random orientation, charge their batteries, then undock, rotate the part and dock again.

Yes, the engines should be attached around - either radial ones (like Thud) or you can attach the tiny tanks radially to a central large tank, stick, say, Terriers on their bottoms, and route fuel from the main tank to the tiny ones with the pipes.

One more approach: stick the claw on top, "traditionally" but give the craft some good RCS, like a few Vernor engines, including ones sticking in the retrograde direction. Use RCS to float/descend/ascend, then turn around.

And yet more: get two or more good reaction wheels and just make the vehicle a rover, drive up to the target, claw it from the side, then set yourself upright fro launch using the reaction wheels - this IS Minmus after all.

Edited August 3, 2015 by Sharpy

[tomf]

I am in the process of bringing a lander can back from Moho. My first attempt with a craft designed to land on the can failed, trying to hover for long enough to land on a target just used too much fuel. My next attempt involved landing a large wheeled frame on Moho, driving it till it was immediatly over the can and jetisoning the legs allowing the body with the claw to fall down and grab. I should have taken some pictures.