Building a good heavy lift vehicle

[Kevin W.]

I'm fairly new to this game and still learning some basic stuff like how to orbit. It's tough to understand all the little details.

Anyway, I want to plan something somewhat ambitious for my first "big" project in-game. Obviously it's something that will require me to understand the finer details of orbiting and docking, so I won't be able to put it into practice for quite some time, but I want to put a station in orbit around Kerbin. What I'd like to do is basically make it a fueling outpost for inter-planetary trips. My idea was to put a station with several Jumbo-64s in orbit so I could launch lighter vehicles, have them dock with the fuel tanks, undock the tanks from the station and then use that to fuel the journey. It'd also require replacement tanks.

Feel free to tell me that my idea is incredibly stupid and pointless and overly ambitious. I'm open to any and all criticism you may have considering I'm still at the point where I have trouble launching a rocket that doesn't fall apart in flight.

Anyway, I'd like to build a station and I do want it to be more than just some orbiting fuel tanks. To build said station I'd like to have a heavy lift vehicle, especially since said HLV would come in handy at other times. All of my attempts so far have been unsuccessful. Does anyone have any suggestions for how to go about building one?

[stupid_chris]

Can you define "heavy" more precisely? Giving a weight in tons gives a good header for the lift vehicle. You're probably going to head for an asparagus staged rocket though, It's the best way to lift over 50t in the game.

[Kevin W.]

Well, I'd like to make a decent-sized station. I won't be making the ISS anytime soon but I know it'll take more than one launch to get everything in orbit. I'm not sure of the exact tonnage though.

[stupid_chris]

Well, I'd like to make a decent-sized station. I won't be making the ISS anytime soon but I know it'll take more than one launch to get everything in orbit. I'm not sure of the exact tonnage though.

Are you planning to send the station in separate modules and dock them or do you want to send it up all in one go? Cause that will make for very different launchers

[Kevin W.]

I'd like to send the individual modules up separately and dock them in orbit. I don't want quite that heavy of a lift vehicle. At least not yet.

Edited July 13, 2013 by Kevin W.

[bsalis]

Do you really want a station? It sounds like you just want to get a fuel tank or tug in orbit, then dock deep space craft to that to head off to Jool or wherever.

A simple Jumbo tank launcher for example...

Used one to get a space plane to Eeloo (after filling it around laythe and docking to said spaceplane)

Or a tug perhaps. Here i'm using one to get a couple of spaceplanes out to Jool.

[stupid_chris]

Alright, I spent a bit of time in the VAB to get something together. I don't think you'll be launching station modules over 50t, the heaviest you could launch is fuel, and an orange tank is 36t so.

Anyway, I came up with two launchers for you:

Javascript is disabled. View full album

Those are very crude and put together very fast (with a heck lot of struts lol), but they do the job.

The first one can carry a payload of 50t to orbit with it's tug, so you can bring it to your station. Altogether, it brings 70.9t to a 75km orbit. But the thing is that with lighter payloads, a heavy launcher can be extremely overshoot and spam the part count for nothing. So the second one is designed to take lighter 20t payloads to orbit with it's tug, for a total of 36.8t to a 75km orbit.

If you want to, I can give you a download link. My goal is not to do things for you, but I mostly learned by looking at other people's working designs and taking them apart to see how they work. Heavy lifters are not that hard, as long as you know what you're doing. Usually, mainsails and well placed and organized asparagus boosters give out a good result. When going in more extreme payloads, different techniques work better, but for everyday's lifting it'S usually the best patter.

Again, just tell me if you want a download. Hope this helps!

[Tw1]

To lift even heavier things, You need more boosters.

Most of my lifters are similar to Stupid_chris's design.

Extra pairs of Boosters can be added in strategic places. You can hold Alt to copy sections of rocket, and this avoids having to rebuild a whole booster each time.

You may need to add extra engines (via radial placement) on inner boosters to maintain your thrust.

Always remember your fuel lines, they should be arranged so fuel is pumped from outer boosters (or the ones you drop first) to inner ones (last). This maximises efficiency.

Edited July 13, 2013 by Tw1

[Thrundar]

Part of the early game play fun for me is building and trying different rocket combinations. No idea if you want to stay strictly stock parts, or use some mods. For me, the massive amount of struts needed to hold much of a ship together really slows my pc down. I found a nice little mod which welded some of the stock tanks together (stacked) on this thread

Really helped reduce the struts/part count. Also have been using Quantum struts, here Those also help reduce how many struts you need.

[stupid_chris]

Part of the early game play fun for me is building and trying different rocket combinations. No idea if you want to stay strictly stock parts, or use some mods. For me, the massive amount of struts needed to hold much of a ship together really slows my pc down. I found a nice little mod which welded some of the stock tanks together (stacked) on this thread

Really helped reduce the struts/part count. Also have been using Quantum struts, here Those also help reduce how many struts you need.

Struts aren't simulated by the physic engine, they're massless during flight, so struts barely affect your gameplay.

[Kevin W.]

No, as I said, while the initial purpose of the station would be to serve as a fueling depot I would like to build it as more than just that so there will be additional modules.

[arq]

I spent awhile learning to put up heavy tankers. A good place to start is putting about 320kL (10 x32 tanks) into LKO. IIRC, this payload is roughly 200t. The biggest one I ever managed to put up in a single launch was 409t, but the strategy is essentially the same.

I use onion staging under the payload with stacks of 2-3 x32 tanks over mainsails (fewer in the middle, more on the outside, to maintain TWR as you lose stages). Just put those outward in rings and you can get most anything into orbit. I recommend using Kerbal Engineer Redux or any other ship calculator to work out the TWR/dV stats. Generally you want TWR in the 1.7-2.5 range and a dV of roughly 4600m/s for putting big stuff up. The real challenge is the sparing use of struts to keep a good framerate while still holding together.

[Kevin W.]

Javascript is disabled. View full album

Which mod do I need to get those stat readouts? Those would be really helpful to have.

[Kimberly]

Which mod do I need to get those stat readouts? Those would be really helpful to have.

Those particular ones are from MechJeb, but you can get similar stats from Kerbal Engineer, which will probably be more useful if stats are all you want (MechJeb has a lot of other stuff).

[Thrundar]

Struts aren't simulated by the physic engine, they're massless during flight, so struts barely affect your gameplay.

Struts are in part count, plus some struts in mods do have mass. Also struts are more objects the GPU needs to draw. So....depends on point of view. Struts can easily double or triple the part count.

[stupid_chris]

Struts are in part count, plus some struts in mods do have mass. Also struts are more objects the GPU needs to draw. So....depends on point of view. Struts can easily double or triple the part count.

Yes, but since they aren't simulated by the physic engine, it can have only half the parts to simulate. That takes a lot of calculations off the CPU, which is much needed with KSP. A ship made of 400 parts with 300 struts will be a lot better for your computer than a 200 part ships without struts.

[Thrundar]

Yes, but since they aren't simulated by the physic engine, it can have only half the parts to simulate. That takes a lot of calculations off the CPU, which is much needed with KSP. A ship made of 400 parts with 300 struts will be a lot better for your computer than a 200 part ships without struts.

I use Ubio's welded tanks, I use far less struts, my PC performs much better. Having wobbly fuel tanks you need to strut or stitch together was about the only major dumb thing I've seen with stock KSP. Oh, and most of the stock fuel tanks look like scrap steel barrels.

[capi3101]

I use Temstar's Zenith Booster family any more. They're a series of asparagus-staged lifters, the largest of which is capable of lifting 160 tonne payloads to LKO. Even if you don't use them directly, you'll probably get some good ideas from how they're designed (he explains their design philosophy here).

[chrischambers]

I also use the Temstar's Zenith Booster family, and once you have the hang of the rockets then you will learn that you can send almost anything up, in one go.

[zanzibar196]

Here is a video walking you through step by step building a heavy lifter:

[lammatt]

how heavy is heavy?

i am delivering a 20- 30t payload with

1. a long 1.25m tank with a nuclear on

2. an central orange tank + 4 radial orange tank (in apparagus manner: drop 2 each time); all running Skipper

the good thing is... you dont even need many struts on this simple design; and the nuclear engine stage can be indeed changed to a double 1.25m long tank stack if you need to increase the interplanetary dV to ~7km/s (you need a few struts to make that long stem stable tho')