Ways to lift a lot of fuel to orbit?

[arq]

An asparagus lifter typically has a payload fraction of 13-16%. This means that for every 1t of payload, you need an additional 5-7t of launcher. My record lift was 409t during 0.20. It was 21 x32 tanks plus a bunch of RCS and some LV-N's to make adjustments (actually it had over 12km/s delta-v because of all that fuel, but with a TWR around 0.1 I wasn't going anywhere fast). On the pad it weighed close to 3000t. You want around 4600dv to get up with some margin, and try to keep your TWR in the 1.5-2.5 range. I usually try to have the first 2000m/s of delta-v have stages with TWRs that begin around 1.7, 1.9 for the next 1500-2000dv, and for the last it doesn't matter much, usually I end up in the 0.8-1.5 range.

For large constructions, Kerbal Engineer Redux (or Mechjeb) is indispensable for calculating TWR and delta-v through your many launch stages.

[Sylon00]

I'm learning so much in this thread. Great stuff guys.

[HeadHunter67]

bigger is still better, at least, once it's in orbit. Bigger fuel tank = more delta V. And besides, I probably don't share the mission profile you do.

Anyway, just understand that right now, in sandbox mode, people just like to play their own way and you shouldn't expect to understand why some folks do certain things

Of course. Understand that right now, I'm simply addressing the topic - which was "how to get a lot of fuel into orbit". Sure, Snarfster's lifter may only deliver one Jumbo to 125km, but it still does so more efficiently than a design that may lift two Jumbos but require more than 16 Jumbos to do it.

When we are talking about Tsiolkovsky's Rocket Equation, diminishing returns aren't simply a possibility - they are an inevitability. Consider the size difference between a Saturn V and a 1-B, and then consider that all the fuel below the third stage exists solely just to get the S-IVB into Earth orbit, and that the entire S-IVB stage was simply to push the CSM/LEM into TLI. The 1-B does a fine job of delivering a CSM into orbit by itself.

Yes, if you want to put a dozen jumbos in orbit at once, you'll need a lot of lifter below it - but it might be more efficient to send up smaller payloads with smaller rockets. When a budget becomes a concern, a lot of these monstrous lifters will become extinct. I'm not trying to tell anyone else how to play, just pointing out that bigger ISN'T always better.

[Captain Sierra]

This is my standard Nova I. It's nothing more than a basic asparagus launcher.

Theoretically, the design could lift 120+ tons to a 100km parkin orbit.

I've never pushed it past 80 tons at once (the again, it can deliver 50+ tons to the Mun easy; and probably at least 25 to Minmus).

80 tons consists of 2 of my standard fuel cans which are, from top down:

standard docking port, adapter, jumbo monoprop tank, jumbo 64 orange tank, adapter, docking port.

Each one weighs almost exactly 40 tons. Here is one that happens to be missing the RCS tank above the jumbo 64.

[Fizwalker]

I'm currently working on a lifter that will put approximately 250* tons to 100km Kerban orbit. Not sure how to post a screen shot yet, but Mk I will be lifting shortly.... Hopefully....

Edit: Mk I destroyed all the de-couplers on the launchpad.... Working on Mk II....

Further Edit: Got up to the Mk XXI (Which did work... Barely) before noticing a flaw--Read: One of the engines was blowing up.....>.> -- that was causing the Mk XVIII to fail at the separation of the first 2 stages... But had been my most promising design. So, fixed my Mk XVIII and successfully got 250 tons into LKO for my refueling depot. ...And have an additional 4 Jumbo 64 tanks and their orbiter, (though the fuel in the orbiter is almost spent, but that is fine because I'm going to use that as the base for a station I will park in orbit around the Mun.... Or maybe Minmus. I'll post a pic once I remember how to take a screenie.

The asterisk is actually closer to the station module and orbiter's overall mass.

Edited September 6, 2013 by Fizwalker

[Captain Sierra]

F1 takes screenies.

Launch clamps. Use them religiously.

[Blaster]

Moar boosters. That always works. Also, firing RT-10's in the upper atmosphere is a surprisingly effective way to get orbit.

[Galane]

How do I change this to Answered?

[Ivan Ivanovich]

Folks, those designs are all fine... until we get realistic drag. Try launching any of them with FAR, I dare you!

[alen74]

One thing I did find was that piping the fuel from the upper side mounted 64 tanks to the *second* dropping ones helped out a lot. Keeping the last two Mainsails around for another tankfull achieved much more altitude. I'm thinking of moving the pipes over to the first pair of Mainsails to keep all the big engines around longer than the first two drop.

[thescientist]

How do I change this to Answered?

Click on "Edit" and then change the Unanswered of the tab near the top of the post.

[rodion]

Well done on this whole thread guys, now I'm inspired. Getting the fully-fueled Jumbos into orbit is one of the most complex and frustrating tasks out there, but I've been feeling like rising to the challenge of getting more than one up for a while now. I'll see what I can hack together.

[allmhuran]

Folks, those designs are all fine... until we get realistic drag. Try launching any of them with FAR, I dare you!

I never quite follow the reasoning behind this kind of comment.

I assume that if someone created a rocket that was two or three jumbos high and then had two radially attached jumbos... your typical asparagus style configuration, nobody would complain about how non-aerodynamic it was.

If someone launched two of them at once, side by side, I again assume nobody would come in and decry the aerodynamics.

Well, most of the super heavy lifters seen here are, really, just a whole bunch of those strapped together. But somehow now that they are actually attached to each other a magic force makes it less aerodynamic?

[superm18]

By the way. In my experience, when i want to lift something tall and/or top-heavy like this: (Eve lander and return at 228 t., with the interplanet return tug at 194 t.) I build sort of an exoskeleton, so that it is stable all the way to orbit. P.S. i know it's overkill, but what the hell right?! edit: the whole thing on the pad is at 3495 t.

Edited September 12, 2013 by superm18

[Kasuha]

Well, most of the super heavy lifters seen here are, really, just a whole bunch of those strapped together. But somehow now that they are actually attached to each other a magic force makes it less aerodynamic?

Actually yes, with just one barrel the air does not have to travel very far to get around it, but sticking many barrels together makes it much harder for the air to pass around or through.

[zcar.300]

For some reason it drains fuel from the top orange tank first. So I just turn that tank off until it's separated. But you have 2871 Liquid Fuel and 3507 Oxidizer left when you launch it to a 200 Km orbit. And it has every fuel type plus electricity to spare. I don't even turn RCS on for launch. I have Clamp-O-Tron SR.s at the top and bottom so many of them can be docked in series at my orbital refueling depot. Plus the other docking ports in case I just want to send it to a stranded mission outside Kerban orbit.

Oh, and everything but the final stage falls back to Kerban so you don't have to worry about space trash.

[allmhuran]

Actually yes, with just one barrel the air does not have to travel very far to get around it, but sticking many barrels together makes it much harder for the air to pass around or through.

But the columns aren't usually jammed tight up against each other (yes for some but not for most since that would make staging difficult or impossible). Rather the columns are usually some distance apart from each other, separated by wide decouplers or, like my design, a structural plate of some kind at the top. As such they really are just many smaller rockets strapped together with some form of space tape.

[HeadHunter67]

[EDIT: My apologies, Allmhuran, if I misunderstood what you said. I took your post to mean that you think two stacks side-by-side would behave no differently than two rockets flying separately, which of course is ridiculous and in defiance of common sense, let alone this game's aerodynamics or actual physics. I must have misread your post.]

Edited September 15, 2013 by HeadHunter67

[allmhuran]

Your presumption of ignorance is neither justified nor endearing. I've done tertiary physics mate, so perhaps you should pull your head in.

The contention is that "when improved physics come in the game" these rockets won't perform as well.

I have no hesitation in making the assumption that there is absolutely no chance that "improved physics" will be modelling the kind of fluid dynamic effects that you are describing here.

Therefore I do indeed absolutely expect these "strapped together" rockets to behave pretty much the same way no matter how "improved" the physics get.

I don't think jet wash means what you think it means. Jet wash, as the name implies, is the wash behind an engine. If two engines are side by side then neither can be affected by jet wash. What you mean to say is "have you ever heard of wake turbulence", which is what I referred to above. Modelling this is extremely computationally expensive, hence my aforementioned assumption.

Edited September 15, 2013 by allmhuran

[Galane]

I'll be happy if all Squad does is make nosecones and tapered adapters *reduce* overall drag instead of increasing it.