The man with the plans

[NovaSilisko]

The External Tank Launch Vehicle

Warning: Hilariously large image

According to some basic calculations, the whole setup has enough delta-v to get into orbit, but I\'m not exactly the best at math.

Let\'s take an unmodified external tank and put an RS-68 on it.

RS-68 mass: 6,597 kg

Navigation, fuel piping, etc: let\'s say 1,500 kg

Total mass: 767,097 kg

Empty mass: 33,597 kg

RS-68 exhaust velocity: ~3.9 km/s

Run that through Tsiolkovsky\'s rocket equation...

Delta-v: ~12.2 km/s

Which should be enough to launch 20,000 kg of payload!

Privately-constructed Lunar Orbit Research Station

Warning: Copypaste from later in thread and wall of text

Not depicted is the Earth Departure Stage, the propellant tank shown is the hydrazine/tetroxide 'Replaceable Stationkeeping Unit', based on the Apollo service module propulsion system (The same the space shuttle\'s OMS is based on, but it used a different propellant. This uses the same prop as the shuttle)

1.3 km/s delta-v in total, more than enough for stationkeeping over a long period.

These components will all fit in 3 Falcon Heavy launches and 1 Falcon 9 launch. 2 Falcon 9 launches if you want to send a Dragon capsule with the ship on its way to the moon.

Replacement of RSU would consist of two launches, one for an EDS, and one for the stage itself. The stages delivered to the moon later have their own navigation systems, allowing them to be docked to the station without an EVA being performed. The initial one has a very basic system, only enough to deorbit itself after being jettisoned. This might seem like a lot of effort to replace the module, but it won\'t be needed very often as the amount of delta-v needed for stationkeeping is minimal, provided you are in a good orbit. As such, much of the initial propellant sent would be used to put the station into as stable of an orbit as possible without making it too difficult for visiting spacecraft to rendezvous with it.

Centrifuge is 17m across, and spins at 6 rpm to generate 0.7g. Can easily be tweaked to move slower, but 0.7 seems like it would be the upper limit for comfort at the given size). The centrifuge is also only a sleep area, and since you\'re laying down in the pods at either end, the Coriolis force is minimized on your body. Should pods contain windows? Would this help or hurt motion sickness?

Further capsules are delivered to the station via Falcon Heavy launches, for crew replacement. Future developments include additions such as multiple docking ports, allowing the station to be used as a 'rest stop' for lunar landing missions.

Current job: calculate the EDS and figure out if a Dragon capsule launched at the moon full of cargo and crew could have the ability to put itself in orbit and rendezvous with the station, or if it needs a new propulsion system (if so, a scaled down RSU could work nicely)

Minor todo: Decide exactly how the station is assembled: LIDS docking system, APAS system or Common Berthing Mechanism, or something in-house

Future: add comms equipment, work out interior of BA-330

Possibly more to come in the future...

[Phoxtane]

I like this idea. My only concern is the ablility of the astronauts to inspect and repair the tank to the proper specs in space-- on the ground, it\'s much easier, as you can always truck in parts or labor needed. Not so in space.

[JupiterII]

on the ground, it\'s much easier, as you can always truck in parts or labor needed. Not so in space.

Sure you can, it just cost a few billion more dollars.

[White Owl]

I remember hearing about this plan years and years ago, using the space shuttle\'s fuel tank as a space station module. Didn\'t they conclude that converting the tank in orbit would be more difficult than just building the module on the ground and launching it with a conventional rocket?

[icefire]

If the tank were to stay in orbit it would need a form of reflective coating to deal with heat/uv light problems, even a simple paint job would be better than exposed tank insulation. The only reason there isn\'t one on the shuttle tank is because it doesn\'t stay around long before breaking up during its sub-orbital reentry

[millsw]

Time to call NASA.

[Howson]

I remember hearing about this plan years and years ago, using the space shuttle\'s fuel tank as a space station module. Didn\'t they conclude that converting the tank in orbit would be more difficult than just building the module on the ground and launching it with a conventional rocket?

I think that was the general consensus, But It would have been extremely useful to have 135 hollow tubes floating around.

[Guest Flixxbeatz]

Build it on ground, and launch it in once piece. Pretty Kerbal, but sounds plausible.

Just add more boosters. 8)

[millsw]

It needs a ring of boosters to give it a kick in the butt on launch.

I mean, the old shuttle boosters are perfectly safe. (sort of)

[thorfinn]

FUCKING A.

Old Werner would be proud of you, and docking can\'t come soon enough.

[rdfox]

But are you the STAR-SPANGLED man with the plan? ;P

[softweir]

Very interesting idea, and I like it.

You say it could carry 20,000kg of payload, but that\'s for an unmodified tank - and I suspect those have got walls too thin to be considered 'safe' for human habitation. My recollection of images of some ISS components is that they were surprisingly thick-walled units. So it may be you would have to make the walls of the tank a lot thicker, and use SRBs to push the I_sp up far enough to carry the additional payload. Even so, that\'s one heck of a cheap space-station component launch.

[icefire]

is 12 km/s enough to orbit when you incorporate drag from the atmosphere?

edit: apparently it is, 10 km/s is the rough dv requirement according to wiki

Regardless I feel like something is wrong with the numbers here, if SSTO with a 20,000kg payload was this easy we would have done it ages ago.

[NovaSilisko]

An alternate proposal could be to replace the docking port with a docking port + fuel pump, and boom, giant orbital fuel depot. Just fill it up with extra launches afterward.

[RedRockets]

??...Question...Question...??

What would you do with all the space, or in other words, how would you design the interior space for the crew?

I will Start...

Divide along the long axis into four quarters.

Do with each what ever you want...

My Ideas...

1. Living quarters, sleeping and eating, and cleaning.

2. Support Systems, Storage, Experiments, ect.

3. Relaxation, Reading, Exercise, View-port, Internet Terminus, and Kerbal Indoor Flying area!!

4. Shooting range for gyrojet pistols!! (that\'s Kerbal)

The Smallest rockets I know of.

RRs

[icefire]

Seeing the image uses an RS-68, and has an MPCV docked to it, I am assuming this isn\'t supposed to be for kerbals.

How about a section for some actual research?

[thorfinn]

Regardless I feel like something is wrong with the numbers here, if SSTO with a 20,000kg payload was this easy we would have done it ages ago.

Remember that it\'s SSTO without a way back: that\'s a substantial difference

SSTO proposals are all about the reusability, that\'s the hard part. The old Atlas was almost a one-way SSTO, after all, and that was the fifties...

[icefire]

I was going to make a counter argument but I can\'t right now my brain has the dumb

[NovaSilisko]

Next thing I draw up is going to be a completely privately funded multipurpose interplanetary vehicle (ages before NASA even gets off the ground again!)

Our powers combine, we are Boeingspacexbigelow!

[thorfinn]

I was going to make a counter argument but I can\'t right now my brain has the dumb

Well, I just wanted to make a point that 'SSTO' usually refers to a reusable rocket, with the associated weight penalties (shields and wings do weigh a lot...) I didn\'t check Nova\'s figures, actually; now that you make me pay more attention to it, I can say that the idea is still sound, but one single RS-68 isn\'t going to get off the ground: he\'d need at least three And that means eating a lot out of the payload margin (seven tons remaining, I believe).

Still, just strap a bunch of the usual Castor rockets around it and it should stop being marginal even in the real world. On Kerbin, well, as we all know by now....

[NovaSilisko]

Well, I just wanted to make a point that 'SSTO' usually refers to a reusable rocket, with the associated weight penalties (shields and wings do weigh a lot...) I didn\'t check Nova\'s figures, actually; now that you make me pay more attention to it, I can say that the idea is still sound, but one single RS-68 isn\'t going to get off the ground: he\'d need at least three And that means eating a lot out of the payload margin (seven tons remaining, I believe).

Still, just strap a bunch of the usual Castor rockets around it and it should stop being marginal even in the real world. On Kerbin, well, as we all know by now....

I did some calculations, it SEEMS like an external tank with a single RS-68 could reach orbit fairly easy. Assuming I got the exhaust velocity figure right (3950 m/s)...

[thorfinn]

I did some calculations, it SEEMS like an external tank with a single RS-68 could reach orbit fairly easy. Assuming I got the exhaust velocity figure right (3950 m/s)...

I trust your figures about Isp and the rocket equation, Nova, but a full ET weighs 767 tons (as you write) and an RS-68 has 343 tons of thrust :

[NovaSilisko]

I trust your figures about Isp and the rocket equation, Nova, but a full ET weighs 767 tons (as you write) and an RS-68 has 343 tons of thrust :

... Damn you Tsiolkolsky for not incorporating that into your rocket equation!

[icefire]

T/W = 3370000/767097=4.39

It\'ll get off the ground.

Also you mislabled the statistics, what you listed is weight, not mass.

Weight = Mass*g

So Mass = Weight/g

Full Mass = 767097/9.807=78,219kg

The DV capacity is still accurate though, as the weight and mass values are proportional.

[thorfinn]

T/W ratio is a go, it\'ll get off the ground.

3370000/767097=4.3

The OTHER way, Icefire ^^

And to make matters even more interesting, sea level thrust is 300 tons actually. Still, I believe the project can stand, at least for Kerbal standards. Four RS-68 would give a comfortable 1.56 TWR at launch: they might be even overkill, actually, considering the late stages of the launch (strongly G limited...) Three units would be quite feeble at the start, and both solutions probably approach a zero payload to orbit: but moderate boosting with SRBs should recover it. In the end, three LFE and a ring of strap-ons would probably fly, with the payload fraction required for man-rating provisions (airlocks, Whipple shields etcetera)