Space tug

[EmanonP]

I've been working on a Mun base, and it's coming along decently. However, each component has had to have it's own propulsion system for landing, which means adding fuel tanks and rockets to the component.

Just the amount of monoprop I need to keep things stable enough to land leaves each component with a warty look.

I've seen many mentions of "space tugs" but just can't quite picture how they function. From what I can figure out, one would deliver a component into Mun orbit, and then dock it with the orbiting "tug"?

The tug would then deorbit and land the component? Components would then need landing legs, and a docking port? Once on the surface, you undock the tug and return to orbit?

I'm also guessing you have to place a fuel source in Mun orbit as well to replenish the tug.

What do you do with the original vehicle that delivered the component? Crash it? Leave it in orbit as debris? Return it to Kerbal and crash it? No matter how I think about it, you will always have to use some sort of

disposable lifter to either get it into Kerbal orbit, (and dock the component with a "tug" that will get it to the Mun) or us the lifter to get to the Mun.

I tried searching Tug, space tug, using tug, etc. The results yield several dozens of pages that don't seem to have the info I'm looking for. If someone has advice on how to better search for answers, I'm all for hearing

about it as well!

Sorry for all the detailed questions. Just looking to get things looking more "sexy" and less utilitarian.

Edited July 23, 2013 by EmanonP

[draeath]

I consider the tug to just be a utility vehicle that attaches to a payload to move it. The specifics of how this is done and what the tug can do is up to you.

I, personally, am envisioning an orbital fuel-dump. Tugs top off, fly to and dock up with a payload, and then do what is needed. I would return the tug to the fuel-dump for resupply and further use.

I wouldn't use a tug for descent/ascent though - but I would use it to deorbit a payload. This way the payload doesn't ÃŽâ€v for this, it only needs to handle the landing (and ascent later, if it is going to do that). Any ÃŽâ€v not expended by the payload is ÃŽâ€v the payload gets to use for other purposes, after all (though this means it will be heavier!)

I'd also use the tug to haul a ship to the fuel depot for refuel, or alternately to haul a fuel tank to the vehicle.

Mods that may help:

Lazor Docking Cam (only if you don't already have the full Lazor mod)

Kerbal Attachment System

Quantum Struts (via quantum core or strut gun - after docking up, you can reinforce via EVA)

[Motokid600]

Make yourself a crane via kerbal attachment system. Land that on the Mun then make a tug. Simply break down your modules into smaller units and load them onto the space tug as best your can. If you can imagine a revolving six shooter. That's how I pack my cylinder modules into my tug using that 6x symmetry. Simply fly it from kerbin, land on the mun, decouple the modules so they fall on the ground, ditch the tug. And assemble with your crane. That's how i do it anyway. Also I don't use landing legs. I just sit each module right on the ground. The cylinders get four feet to keep them right side up and that's it. Makes lining up docking ports easier imo

Edited July 23, 2013 by Motokid600

[draeath]

Moto, do you make your cranes pivot, or do you just use them as a sort of A-Frame and move stuff around underneath for positioning?

[Motokid600]

The A-frame to keep it simple. Like a tall boat crane it straddles each module.

[espm400]

AFAIK, most people use 'tugs' (trying not to make a joke here...) for orbital maneuvering during station building and the like. I suppose you could use one for decent of a payload, but it just seems to me that it would be terribly inefficient.

As for using tons of RCS on landing, are you trying to land massive pieces at once? My strategy has always been to limit the pieces I land on the Mun to something under 20-30 tons and that fits into the KW Rocketry fairings. This way, as long as it's mostly balanced, all you need is a small decent stage with ASAS and some landing legs to land without any RCS at all.

As for building cranes for use on the Mun, I generally just stick to Romfarer's 'Robotic Arms Pack'. I did try to make a Liebherr 1250 with Damned Robotics, but could never get the boom rigid enough (another joke here...). Currently I'm in the process of building a modular Liebherr 1300, but that's still a while off.

[blizzy78]

I made myself a tug that I use to land or lift things all the time (see signature.) The thing just docks with the payload, secures it using Quantum Struts, and does its thing.

[draeath]

AFAIK, most people use 'tugs' (trying not to make a joke here...) for orbital maneuvering during station building and the like. I suppose you could use one for decent of a payload, but it just seems to me that it would be terribly inefficient.

Depends what you're doing. If you're trying to land something small, it may not be able to do that itself (imagine a "drop-pod" on duna with parachutes without any engines)

I made myself a tug that I use to land or lift things all the time (see signature.)

Did Spaceport freak out, or is something wrong with your upload? There's only a link to a .craft file, no description, pictures, or any page content really. Seems weird.

[troyn123]

Hmm... a decent orbital-tug design is to just have a couple fairly efficient engines pointed in opposing directions with an action group to swap which ones are active (move forward or back without turning), and a bunch of RCS for fine alignment:

I wouldn't want to try landing something on the Mün with it though. For my Mün base, I went with the smaller, docked-component approach many on this forum suggest. Each piece came down vertically on it's own lander component (X200 fuel tank, Poodle engine, bigger landing struts, and a big docking clamp on top that the base components attach to). It flies the component down, lands, decouples the component, a bit of RCS pushes it over onto it's wheels, and then it drives off to dock with the rest of the base. The lander can return to my Low Kerbal Orbit station for reuse, but I've been lazy lately and just ending it's flight.

[blizzy78]

Did Spaceport freak out, or is something wrong with your upload? There's only a link to a .craft file, no description, pictures, or any page content really. Seems weird.

Must be a Spaceport thing. I've most certainly added description and pictures.

[draeath]

Careful with those engines though, if whatever you are hauling blocks an engine it will cause your applied thrust to be asymmetric and might cause an unplanned orbital rendevous

I don't have the link handy but you can test this on the ground by putting panels or whatever behind your engines and observing what happens.

Must be a Spaceport thing. I've most certainly added description and pictures.

This is all I see... odd.

Edited July 23, 2013 by draeath

[Anton P. Nym]

I'm testing an interplanetary space tug; a Rockomax double-sized tank feeding a pair of the FL800s with LV-N rockets. I fly up a probe, the tug then docks with the probe and (hopefully) does the planetary transfer burns for the probe. If I've done it right, it's currently hauling a sample return probe to Duna and back.

This saves hugely on launch weights for the probe, and if it works I won't have to worry about discarded planetary transfer stages roaming the system when "Era 21" comes around and makes my current debris-cluttered save obsolete.

-- Steve