Orbital Tug using KAS

[flyin_ruski]

This is a test tug that I built using KAS. It features 4 winches and spare magnets.

THe magnets have to be attached via EVA which adds a little bit of fun (or frustration) to the mission.

So far the practical application for it would be limited to LKO debris clean up but I have plans to build a sort of carriage and use the Tug for the inter-planetary stage.

The object the Tug is towing in the pictures is an early test for said carriage.

[leax256]

I made a 5 or so ton debris deorbiter, it was too light to work the way i was using it.

[regex]

I'm interested in whether the towed object bounces towards the tug when burns are done. If not, this could be quite fun for interplanetary craft. I would much prefer using KAS cables instead of docking ports for puller designs.

[Scotius]

Is it stable in flight? I had bad experiences with towing larger pieces of debris with KAS cables. Some behaved like giant jo-jo threatening to swing all the way around and slam into my tug. Other started losing parts while towed, creating more debris. And sometimes physic just glitched breaking one or both ships or even crashing the game. Granted, it was with one of earlier versions of KAS - i didn't try it since.

[Tiron]

The whole point of magnets is that they don't have to be placed Via EVA unless you're trying to place them very precisely. In which case, you might as well use detachable connectors and save the electrical usage.

[flyin_ruski]

The vessel I was towing had special mounting points for the magnets. I needed them places exactly on the points to avoid unstable flight characteristics.

The magnets aren't mounted on docking ports and the only port I have is for refueling the tug.

So far it flys ok but I've only done very basic maneuvers such as raise and lower apoapsis and preapsis. Gonna test a de-orbital burn today on discarded stage. Ill post pictures to show the end result!

[Geschosskopf]

In my experience using KAS in space, you have to be pretty careful with it. I have run into 3 problems; there may be more .

The 1st, most important to your attempts at a towing, is that it's very hard to get both the winch and the connection on the other end liked up properly on the centerlines of both ships. If it's not that way, you tend to get lots of gyrations and tumbling. And even if you get this down, you can't maneuver, only go straight ahead. As soon as the towtruck rotates to burn in another direction, it has a the mass of the other way off-center. Or at least it was that way in my attempts.

The 2nd problem is the unpredictable one you sometimes run into on the ground: the phantom forces. That is, the winch cable suddenly exerts a strong pull on the ships on the ends, but doesn't actually move them closer together, just cocks them towards each other. On the ground this is bad enough but in space, it can result in VERY rapid gyrations of the 2 ships until something breaks. To avoid this, do the same preventive measures you do on the ground. That is, extend a lot of slack in the cable, move it to the other ship via release mode, connect it undocked, let out some more slack, then connected docked. Of course, this is only an issue if you need to use the cable in docked mode.

The 3rd problem is that if your Kerbal has a winch part or connector on his back when he reboards a capsule, that part is lost and that Kerbal loses the ability to make connections with other parts. I discovered this by getting all ready to EVA to a stranded ship with one of those dismountable ports, but then deciding to wait until the sun came up and went back inside. To avoid this problem, don't go back inside while holding winch parts

[flyin_ruski]

I know what you mean about maneuvers. I have very slowly and carefully maneuver above the behind the towed object then use RCS or very low engine thrust to avoid any crazy whipping or swinging.

There is also an issue which switching back to the tracking station while the winches are attached