Interplanetary Tugs

[Dkmdlb]

Let's have a discussion on interplanetary tugs. How many LV-Ns are you using? How do you attach them? How do you manage fuel? What docking ports? Have you discovered any tricks that are helpful to you?

Let's see some pictures.

[Geschosskopf]

This is my standard interplanetary tug, shown here in the act of docking with a mission module. I have a very standardized space program where the standard tug and all mission modules fall in or near the 30-40 ton range, so everything goes up on the same lifter and most interplanetary ships consist of 2 pieces: the standard tug and the mission module. With the tug attached, such ships typically have about 4200m/s delta-V, enough to go most places.

As you can see, the standard tug is pretty simple, just the big nuke engine, the 3-high metal fuel tank, some RCS, reaction wheels, a probe core, a Sr. docking port, and 2 RTGs. The engine and tank are KSPX at present but I bet they'll be stock in 0.22. 1 big nuke has a SLIGHTLY better TWR than 2x LV-Ns as well as fewer parts, and makes using the superior Sr. docking port a breeze.

There are occasions, however, when I want more thrust and/or more fuel, and/or a docking port on each end. In such cases, I replace the big nuke with another Sr. port and put 4x LV-Ns with small tanks on outriggers.

[Nasakev]

My tugs are quite simple: a central fuel tank with docking ports on the front and back, surrounded by several radial nukes. The payload ship can be mounted on the front docking port nicely, and as many fuel tanks as I need can be docked to the back of the ship, to be undocked when expended. This design has technically unlimited delta-v, as you can dock as many fuel tanks as you please.

[Captain Sierra]

This depends. Are we talking tugs or interplanetary drives? My tugs are moreso for space station service.

[capi3101]

The tug I've had the most luck with consists of a Sr. Docking port, a large probe core with RTGs, five X200-32 tanks arranged one centerline and four outboard with fuel lines running inboard, and five nukes attached to the centerline tanks (one on the tank's bottom attachment node, the other four with BZ-52s). With a light load she'll get up to 12,000 m/s of delta-V.

I have tried a design that foregoes the outboard X200-32s with X200-8s and where each tank has five LV-Ns attached (for 25 LV-Ns) total; good thrust but come to discover (surprise surprise) that it actually has fairly lousy delta-V on its own. I haven't sent it anywhere yet; haven't had a payload that really needed that much thrust yet.

[geb]

This is my standard tanker/tug. It reaches orbit with a lot of fuel still in its launch booster, so you can use that to top up the tanks of your payload and give a bit of extra delta-v at high thrust for your departure burn. Once you ditch the launch booster, it's one orange tank and one LV-N. It accelerates really slowly, but it has enough kick to push a small space station into Eeloo orbit.

[JerryIRacer]

These are mine

Nuke I am using is equivalent of 3 stock ones. 3 times the mass and thrust. I like to use some additional engines for initial burn to bump TWR and shorten burn time.

[bsalis]

I went with a wide, push-and-pull design. Lots of LT-Ns, with modest fuel. Can pull decent loads out to Jool.

Here are a couple of caravans, the tug is the one with four arms...

Towing a couple of tankers...

Towing a spaceplane and pushing another...

[Technical Ben]

As I posted in another thread. I'm currently using, 2, 3, 4, 6, 8 and 12 LVNs on about 6 different tugs... so yeah, I'm getting a feel for them all.

[Szkeptik]

I only use IP tugs to boost up the mission stage to the proper escape velocity out of Kerbin SOI, then the tug undocks and returns to a standard Kerbin orbit.

I have 4 LV-N-s on the tug, but that's well enough. The heavier modules need about 10-15 min boosts to reach the outer planets, but that's ok with me. As long as aerobraking around Jool is there, the mission module itself doesn't need excessive amounts of fule to land on a Joolian moon and even return.

Edited October 2, 2013 by Szkeptik