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Ateballgaming

What is more efficient

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Im thinking of building my own station and I was wanting to do it with the kso mod for historical accuracy, but would it be easier just to do it with rockets instead of a shuttle?

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It's certainly much easier and efficient to do with conventional rockets. You won't have to worry about varying module masses messing up your CoM, you can launch bigger modules at once, you can launch heavier modules.

Don't let that stop you if you think it'd be fun to do with a shuttle though, it's all about what you enjoy most.

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It's certainly much easier and efficient to do with conventional rockets. You won't have to worry about varying module masses messing up your CoM, you can launch bigger modules at once, you can launch heavier modules.

Don't let that stop you if you think it'd be fun to do with a shuttle though, it's all about what you enjoy most.

Thanks for the reply, ill probably just end up bulding the heavy stuff with rockets, and the lighter modules with the shuttle :)

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It's certainly much easier and efficient to do with conventional rockets. You won't have to worry about varying module masses messing up your CoM, you can launch bigger modules at once, you can launch heavier modules.

Don't let that stop you if you think it'd be fun to do with a shuttle though, it's all about what you enjoy most.

Has anyone tested that fact recently? I know Shuttles are less fuel efficient but is it less cost efficient? Assuming stock, you can't stage recover a conventional rocket but you can recover the entire shuttle. This was the original idea behind the NASA Shuttle in the first place after all.

So does the cost of the SRB's and External tank, plus all the decouplers and struts, and whatever fuel it takes to circularize really add up to more than an entire conventional 2 stage rocket that can lift the same mass? Without any testing, I feel like it would take at least a Mainsail to lift as much. That thing is 13,000 by itself, that's the same cost as a S3-14400 tank full of fuel.

That might be something interesting to try, though I'm not going to bother before 1.0.5 since we are getting a new shuttle engine.

Edited by Alshain

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Has anyone tested that fact recently? I know Shuttles are less fuel efficient but is it less cost efficient? Assuming stock, you can't stage recover a conventional rocket but you can recover the entire shuttle. This was the original idea behind the NASA Shuttle in the first place after all.

So does the cost of the SRB's and External tank, plus all the decouplers and struts, and whatever fuel it takes to circularize really add up to more than an entire conventional 2 stage rocket that can lift the same mass? Without any testing, I feel like it would take at least a Mainsail to lift as much. That thing is 13,000 by itself, that's the same cost as a S3-14400 tank full of fuel.

That might be something interesting to try, though I'm not going to bother before 1.0.5 since we are getting a new shuttle engine.

You CAN recover conventional rockets - it just takes a little work. Check out Warzouz' Cygnus Recoverable Rockets for an excellent example of recovering conventional rockets.

Danny.

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You CAN recover conventional rockets - it just takes a little work. Check out Warzouz' Cygnus Recoverable Rockets for an excellent example of recovering conventional rockets.

Danny.

Warzouz' rockets are not conventional, they are SSTO. We were specifically discussing conventional rockets. (There has never been an SSTO, plane or rocket, in real life so you can't really call them conventional) You could recover the top stage with a probe, but without mods it would be very difficult to recover the first stage of a two stage rocket.

Edited by Alshain

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Has anyone tested that fact recently? I know Shuttles are less fuel efficient but is it less cost efficient? Assuming stock, you can't stage recover a conventional rocket but you can recover the entire shuttle. This was the original idea behind the NASA Shuttle in the first place after all.

A single liquid core stage with disposable SRBs will beat a shuttle every time. It's the same staging efficiency and and nearly the same recoverability as a shuttle, only it's not carrying all that extra mass of wings and cargo bays and a big crew capsule, and there's no cosine losses on the liquid engine.

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Warzouz' rockets are not conventional, they are SSTO. We were specifically discussing conventional rockets. (There has never been an SSTO, plane or rocket, in real life so you can't really call them conventional) You could recover the top stage with a probe, but without mods it would be very difficult to recover the first stage of a two stage rocket.

A bit inconvenient, maybe, but not super difficult. The fact that you can only control one thing at a time in KSP adds an artificial obstacle, but it's reasonably doable.

I tried this for a while and it worked reasonably well: Two-stage rocket. First stage packs enough oomph to get a near-suborbital trajectory (Ap right around the top of atmosphere, or a bit lower). When the first stage burns out, fly the second stage. Either do a direct orbit injection (for very low orbits), or another boost that raises Ap up to something significantly higher that's at least a few minutes away. Either way , the second stage only requires a minute or so of attention after separation. At this point, immediately switch back to the first stage, which has been coasting since separation. It has a probe core so is controllable. Fly it all the way down to a landing and recover. Then switch back to the second stage.

I only played around with that briefly, mainly because the economics just didn't make sense. Funds are pretty easy to come by in KSP (at least, unless you play on hard difficulty, which I usually don't), and I found that the relatively paltry amount of cash I saved by recovering the stage simply wasn't worth the extra time and hassle to me. It was fun as a novelty for a few launches, but that was enough for me.

That's also why l don't bother with SSTOs in KSP. I just don't see the.point, they're not worth it to me.

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A bit inconvenient, maybe, but not super difficult. The fact that you can only control one thing at a time in KSP adds an artificial obstacle, but it's reasonably doable.

I tried this for a while and it worked reasonably well: Two-stage rocket. First stage packs enough oomph to get a near-suborbital trajectory (Ap right around the top of atmosphere, or a bit lower). When the first stage burns out, fly the second stage. Either do a direct orbit injection (for very low orbits), or another boost that raises Ap up to something significantly higher that's at least a few minutes away. Either way , the second stage only requires a minute or so of attention after separation. At this point, immediately switch back to the first stage, which has been coasting since separation. It has a probe core so is controllable. Fly it all the way down to a landing and recover. Then switch back to the second stage.

I only played around with that briefly, mainly because the economics just didn't make sense. Funds are pretty easy to come by in KSP (at least, unless you play on hard difficulty, which I usually don't), and I found that the relatively paltry amount of cash I saved by recovering the stage simply wasn't worth the extra time and hassle to me. It was fun as a novelty for a few launches, but that was enough for me.

That's also why l don't bother with SSTOs in KSP. I just don't see the.point, they're not worth it to me.

Yeah, but doing it that way would be terrible fuel efficiency. Having a booster stage go to suborbital would mean a rather vertical launch, if you did it horizontally then it would be practically an SSTO anyway since that type of launch usually has your Pe pretty high by the time you reach suborbital.

- - - Updated - - -

A single liquid core stage with disposable SRBs will beat a shuttle every time. It's the same staging efficiency and and nearly the same recoverability as a shuttle, only it's not carrying all that extra mass of wings and cargo bays and a big crew capsule, and there's no cosine losses on the liquid engine.

Same staging cost, yes. But you are throwing away an LFO engine as opposed to recovering it with the shuttle.

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Didn't Slashy and Co. already crunch the numbers on this? SSTO Spaceplane for crew/tiny cargo to LKO, and rockets for everything else?

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Same staging cost, yes. But you are throwing away an LFO engine as opposed to recovering it with the shuttle.

Single recoverable core stage and disposable SRBs. No LFO engine is discarded.

Didn't Slashy and Co. already crunch the numbers on this? SSTO Spaceplane for crew/tiny cargo to LKO, and rockets for everything else?

Airbreathing SSTOs beat everything, cost wise, even for larger payloads. If one truly wants the most cost efficient space program they will never launch a rocket, everything will go up by airbreathing spaceplane.

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Has anyone tested that fact recently? I know Shuttles are less fuel efficient but is it less cost efficient? Assuming stock, you can't stage recover a conventional rocket but you can recover the entire shuttle. This was the original idea behind the NASA Shuttle in the first place after all.

So does the cost of the SRB's and External tank, plus all the decouplers and struts, and whatever fuel it takes to circularize really add up to more than an entire conventional 2 stage rocket that can lift the same mass? Without any testing, I feel like it would take at least a Mainsail to lift as much. That thing is 13,000 by itself, that's the same cost as a S3-14400 tank full of fuel.

That might be something interesting to try, though I'm not going to bother before 1.0.5 since we are getting a new shuttle engine.

Alshain,

A semi-disposable vertical lifter (disposable first stage and recoverable upper stage) will always beat a shuttle for cost- effectiveness and it's much easier to design and use.

Didn't Slashy and Co. already crunch the numbers on this? SSTO Spaceplane for crew/tiny cargo to LKO, and rockets for everything else?

sardia,

I use spaceplanes for crew and supplies to LKO, but never cargo (small or otherwise). They *can* be used to carry cargo and they're cheaper when they are, but I don't think they get used often enough to justify their existence and they limit the size and shape of the cargo.

Best,

-Slashy

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Im thinking of building my own station and I was wanting to do it with the kso mod for historical accuracy, but would it be easier just to do it with rockets instead of a shuttle?

Ben, I'll say just one word - StageRecoveryModIsWhatYouNeedToSaveThemFunds.

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"Easiest" is a single launch station, think Skylab rather than ISS.

Cheapest would I expect be something all reusable. KSP streamer Matoroignika has a couple of Falcon 9 style rockets and he's got it down to a fine art, landing the first stage under power back at KSC, no need for FMRS or Stage Recovery, but he's yet to make a reusable upper stage for them.

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(regarding my description of a two-stage-to-orbit system that recovers the first stage, in stock without mods)

Yeah, but doing it that way would be terrible fuel efficiency. Having a booster stage go to suborbital would mean a rather vertical launch, if you did it horizontally then it would be practically an SSTO anyway since that type of launch usually has your Pe pretty high by the time you reach suborbital.

No, the fuel efficiency was just fine, and it was actually a fairly conventional launch-- neither excessively (i.e. wastefully) vertical, nor the extremely-horizontal profile of an air-breathing SSTO. Just your basic gravity-turn, 45-degrees-at-10km, lob-it-to-parabolic-suborbital, do-a-burn-at-Ap-to-circularize type of launch, with the added wrinkle of recovering the first stage.

I'm usually a three-stage-to-orbit kinda guy (e.g. "Thumper, Swivel, Terrier" or "Thumpers, Skipper, Poodle" or "Kickbacks, Mainsail, Skipper"), which averages out to 1000+ m/s per stage (admittedly, not evenly distributed among the stages). Going to two stages from three means it's 1500+ m/s per stage instead of 1000+ ... but that's still a far cry from the 3000+ m/s you need from an SSTO. Both mathematically and in the "feel" of the launch, it's much closer to a conventional three-stage-to-orbit rocket than to an SSTO.

My fuel efficiency was just fine. I also played around with using air-breathers (bunch of radially attached Whiplashes, this was before Rapiers were available on that career) on the first stage of the vertical-launch rocket, and it actually worked pretty well-- gave 'em just a brief initial jolt from the LFO main engine to help get them spooled up, and then they worked great. Got the best of both worlds: the high Isp of jet engines, without the dead weight of lugging them all the way to orbit. Would be a pricey design for a throwaway first stage (jet engines are expensive), but worked pretty well with recovery.

So from an engineering and economic perspective, it was a win. The reason I only did it briefly was mainly because it got tedious really fast: I do a lot of launches, and I enjoy doing launches, but babysitting the 1st stage back to earth was eating up time and was really dull for me. The most precious commodity in KSP (for me) isn't funds, it's my own time, and I want to spend that time doing whatever I personally find to be fun. :)

(And besides, for completely irrational reasons, I just didn't enjoy it as much. I like SRBs, I like the massive-pillar-of-flame-and-huge-cloud-of-aluminum-oxide-dust effect, I like the visual drama of casting away stages as I punch a hole in the sky and go shrieking up to the quiet dead calm of orbit. It's a story that speaks to me on every launch, never gets old, and-- simple though it may be-- is a big part of what keeps me hopelessly addicted to KSP. Stepping out mid-launch to pick up the pieces was like cutting away to a mutual-fund commercial right in the middle of a show's climactic action scene. It was a total buzz-kill for me.)

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I'm not sure a space shuttle replica would be a good solution, but the mk3 spaceplane I built out of stock parts in sandbox mode is great. Easy to fly, reusable, good mass fraction, and very safe.

The problem(s) with space planes

1. Attaching loads is much harder. Even in a type 3, can be awkward getting stuff in the cargo bay. Tried making an aircraft with twin tailbooms, leaving a place to attach a load with fairing at the end of the mid fuselage, but stuff doesn't want to snap in.

2. Takes longer to get to orbit. It's a lot of fun, but yeah with a rocket it's over much sooner, one way or another.

3. In career mode, aircraft techs are too far away. Retractable undercarraige came in the 1920s, before the Apollo program. The first kind of jet engine was the turbojet, which is actually better at high speed/altitude than the turbofan, went to mach 2.8 on the mig-25. The SR71 blackbird was a turboramjet, 1960s/70s tech, top speed/altitude limited by skin heating.

4. In career mode, there are no airports other than the KSC. Many of my early space planes were sub-orbital, first stages for the rocket interplanetary vehicle. They'd land off-airport on the opposite side of the world from the space centre, so i'd only recover 25% of the cost of the plane , even though it is completely intact and just needs topping up with jet fuel to come home. Would actually work out cheaper to use disposable rockets :-(

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