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Rockets versus space planes


Australian Sloth
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G\'day guys and gals.

So, I finally got around to watching some more of Kurt\'s ksp videos, specifically the sub orbital space plane one.

It got me thinking, which is more efficient in terms of fuel consumed versus mass to orbit, a space plane launch or a rocket launch. I did some testing and I think that vertical rockets are definetly better for heavy payload delivery and easier to construct. I understand that data will differ from design to design, but it is likely there is a general trend.

What do you think, could someone with skill at building both try and get some data that we can see?

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It seems like space planes are much worse then rockets for leaving the atmosphere, but atmospheric engines are incredibly efficient. For getting things into space rockets are going to be best at least for now. I\'ve been trying as hard as possible to make a real effective space plane for deep space missions but I just can\'t seem to do it.

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Vertical launch, with atmospheric engines acting as boosters is probably the most efficient at this time. The real advantages of (aero)spaceplanes would be for messing around in the atmosphere for extended periods of time, and gliding landings (for better control over landing site). Both of which I expect to be more useful as the worlds and economy get fleshed out?

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The current game conditions are in no way final or realistic in this regard. The whole point of a spaceplane in the real world, I believe, is to use an air-breathing engine to reach high speed and altitude without consuming as much oxidizer as a rocket. Once in the high reaches of the atmosphere, there\'s no distinction between the two anymore: they\'re both rockets. So the answer to your question is that in the real world a spaceplane would unquestionably be more efficient, whereas in the game world it\'s kind of random right now and will change soon anyway. Not that it isn\'t an interesting question. :)

Oh, and a spaceplane would be reusable whereas rockets generally are not, making the spaceplane more economical, whereas in the game they both cease to exist as soon as you hit 'end flight,' so there\'s no savings on recycling.

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I\'ve found rockets are far easier to launch and land, especially with parachutes and are easier to build.

Space planes are definetly more fun to fly and make. But wayyyyyyyyyy harder to do make and fly.

I actually have fun making and refining my spaceplanes, then even more fun crashing them in realisation I didn\'t have enough canards.

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Personally, my new favorite is vertical launch rockets, but space plane landing. I can end up on planet exactly where I choose to be which is much more efficient for fuel landing and more controllable it seems. As of yet, there is not much function to them however and I can control my re-entries well enough to get close with parachutes. I think the best use of a space plane will come if we get another atmospheric planet. A plane lander could allow an effective landing and takeoff again, but still dunno if a plane can be effective for out of orbit at all.\

Lastly will be the IVA stuff. The space plane items are larger but have less fuel. Re-entry heat shielding etc means that it might become the only way for utility and landing in more advanced space missions.

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space planes are DEFINITELY harder to get into orbit, don\'t consider even getting them to the moon! but later, when money will be implanted, then space planes are a LOT cheaper. rocket parts will shatter around in space, while a good spaceplane gets back with all the parts which it launched with, so it can be re-used :D.

this is the same reason why the space shuttle is used. ALL the parts are re-used, even the boosters to get it into orbit ;) i think that\'s the reason why space planes are implanted.

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I built a pretty solid spaceplane that can get to the mun, land, fly to minmus, land, and then fly back to kerbin and land at the KSC. Total trip was over 3 days for my poor kerbals cooped up in a fighter cockpit, however.

I used stock parks with one important exception; In addition to 3 turboprop engines I strapped 4 small radially mounted low-thrust low-consumption gimbaled rockets to the bottom center. The total thrust is maybe 160, at a cost of about 4 fuel units per 'cycle', making it less efficient than nuclear but more efficient than a single stock gimbaled engine.

All of that said, my plane rolls easily and requires heavy use of ASAS to keep a heading. if you take the ASAS off it is stable vertically but rolls so easily its almost unflyable. Npt sure why; it rolls left despite having perfect symmetry.

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On Earth, the real beauty of the Spaceplane (or the carrier aircraft launching a rocket) is the fact that the aircraft can be launched anywhere, freeing the rocket from a particular launch site. There\'s no practical reason why the aircraft can\'t fly to the Kamchatchka peninsula for one launch, followed by another launch from Rockhampton in Queensland. You don\'t need a gantry or special refuelling systems, and a change in inclination is managed easily.

All of this means that for getting a spacecraft into a particular orbit, you won\'t be able to beat a carrier aircraft launch.

You\'ll also not have to worry about weather, as you launch from the stratosphere (which is well above the clouds).

So really, it\'s not pure efficiency that is the attractive feature of concepts like stratolaunch (Yes, the rocket effectively launches a couple of kilometres up, but you can do that with well-designed staging sequences). Rather, it is operational efficiency obtained by increased flexibility.

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On Earth, the real beauty of the Spaceplane (or the carrier aircraft launching a rocket) is the fact that the aircraft can be launched anywhere, freeing the rocket from a particular launch site. There\'s no practical reason why the aircraft can\'t fly to the Kamchatchka peninsula for one launch, followed by another launch from Rockhampton in Queensland. You don\'t need a gantry or special refuelling systems, and a change in inclination is managed easily.

All of this means that for getting a spacecraft into a particular orbit, you won\'t be able to beat a carrier aircraft launch.

You\'ll also not have to worry about weather, as you launch from the stratosphere (which is well above the clouds).

So really, it\'s not pure efficiency that is the attractive feature of concepts like stratolaunch (Yes, the rocket effectively launches a couple of kilometres up, but you can do that with well-designed staging sequences). Rather, it is operational efficiency obtained by increased flexibility.

Not to forget, the runways used for the carrier aircraft\'s can be used for all sorts of planes. If you build a launch pad somewhere, it will launch rockets, and that\'s it.

On the other hand, a pure spaceplane will always be worse for delivering cargo into orbit. A spaceplane carries alot of dead weight that is plain useless once your out of the atmosphere. All this weight will decrease the cargo capacity. And that\'s why there are no spaceplanes around.

I guess the game will have a pretty hard time to make a true spaceplane competitive once some sort of economy is in.

At least for delivering stuff into orbit. Retrieving payloads from orbit is an entirely different story. That is probably most efficiently done with some kind of Space Shuttle like system. Unfortunately there aren\'t many things that require being taken out of orbit and brought back to the ground safely.

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space planes entirely assembled within the VAB do not have an auto-induced roll
What if you use the trick of building the plane part in the SPH and copying the file to the VAB to put a rocket under it? Does it bring the glitch with it?
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I prefer playing with ballistics in KSP, but I have found that with smaller rockets, using turbojets as boosters(even solo launch units), is awesome for considering fuel management and weight. I aim to use them for quick vehicles to get small parts into orbit when docking occurs and we can assemble craft and stations in space. Not to mention they make the craft look AWESOME.

9OC2a.png

Makes me wonder if jets this large could be used for vertical take-offs for personnel transport into orbit in real life? I doubt they would be practical for cargo or satellite transport, but for ferrying people they might be handy.

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Oh, and a spaceplane would be reusable whereas rockets generally are not, making the spaceplane more economical, whereas in the game they both cease to exist as soon as you hit 'end flight,' so there\'s no savings on recycling.

Not entirely true, This was the main fault of the Space Shuttle Program, You would think a re-usable plane is cheaper, But in reality it\'s more expensive.

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Not entirely true, This was the main fault of the Space Shuttle Program, You would think a re-usable plane is cheaper, But in reality it\'s more expensive.

Besides, rockets don\'t have to be non-reusable:

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The idea of the Shuttle program was that the greater cost of a reusable launch system would be compensated for by turning them around and relaunching them quickly.

This was a good idea in theory. In practice, it didn\'t work because the turnaround for the shuttle proved much more time and labour intensive than expected. Therefore, when NASA was hoping for as many as 50 launches per year, the best year ever (1985) saw 9 missions - impressive, certainly, but nowhere near that needed to make the program cost-effective.

The key thing in an orbital spacecraft is mass, and this makes a spaceplane problematic. The bottom line is that you need to accept a mass penalty if you are going to take wings and landing gear into orbit.

One solution to this is the idea of using the aircraft as a bottom stage. This is attractive for the reasons in my previous post as well as that of using efficient air-breathing engines until the combination is ready to depart the atmosphere. It has a disadvantage, however - the most useful part of the mission for a winged spacecraft is entry (because it allows for greatly enhanced manoeuvering on landing), but if you\'ve left the wings and jets below, you\'re limited to blunt-capsule re-entry.

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You would think a re-usable plane is cheaper, But in reality it\'s more expensive.
Perhaps so while the technology still isn\'t mature, but there\'s a reason you don\'t throw your car away every night and buy a new one every morning. :D The space shuttle was the first of its kind, so of course its not optimized for the role, but the concept of a reusable spacecraft has not been abandoned.
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I may be playing at being the devil\'s advocate here, but I honestly prefer non-reusable launch vehicles for the simple fact that they can be mass-produced. Even better if they are modular. For example, I give you the Interorbital Systems Neptune 35 and the incredibly kerbal (and Lunar-orbit capable) Neptune 1000. Yes, those are the same fuel tanks and rockets.

Pretty Pictures:

Neptune 35

N30%20Above%20Eua%20W1.jpg

Neptune 1000

Neptune-1000-assembly-Plume-1-Ocean-Background-Insert-1-X-Logos-1-NB-Small.jpg

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