Discussion Orbital Propellant Tanker

T.Neo

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An idea I had a week or two ago, a launch vehicle exclusively for delivering liquid hydrogen propellant to orbit, to supply a fusion spacecraft or similar. This concept uses hydrolox propulsion with a common bulkhead between the LOX and LH2 tanks; the payload is contained in the same tank as the fuel.

Not sure why it is called "orbital", as it isn't an orbit-only vehicle, it doesn't go from orbit to orbit or anything like that; effectively it's just a species of launch vehicle. But it does launch to orbit, I guess.

The sunshade isn't shown or described in the document, but I've envisioned it as basically a sheet of solar sail material (not for any propulsive purpose, it's just lightweight and reflective) extended on spring-loaded booms, somewhat similar to long, thin antennas. I know this arrangement doesn't provide 100% effective shielding, but for what it's worth, it provides at least some shielding.

Don't take all of the numbers too seriously, a lot of the smaller mass breakdown figures are more or less thumbsucks by me, and the cost per kg is at best very rudimentary. Nevertheless, if you spot something that's blatantly, obviously, horribly incorrect, please tell me.

Overall I generally need a cheaper cost/kg figure, which would probably require a less... mundane system, but for what it's worth I think it is rather nice. I'm sure it has a use somewhere in the Orbitersphere.

The only real downside, is that it ended up looking like a feminine hygiene product. :facepalm:
 
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Moach

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The only real downside, is that it ended up looking like a feminine hygiene product. :facepalm:

well, a "man's way" to correct for that is to add a couple of very butch SRBs to it :lol: - yeah, few things pack as much testosterone as a giant stack of solid-fuel that can't be put out after being lit :headbang: -- grunt! beer me up! and bring us more bacon! :cheers:


but fins could do the trick just as well... i guess...


anyways - i love the concept, i had envisioned G42's regularly being assigned fuel-ferry for supporting interplanetary missions :hmm: but this is more present-day, i think :tiphat:


i say go for it! :thumbup:



and then it hits me again how badly we need that general-purpose control-room-shaped attachable DVC hookup :rolleyes:
 
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thegrogen

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well, a "man's way" to correct for that is to add a couple of very butch SRBs to it :lol: - yeah, few things pack as much testosterone as a giant stack of solid-fuel that can't be put out after being lit :headbang: -- grunt! beer me up! and bring us more bacon! :cheers:

Well, you CAN shut off an SRM, but in order to do so, you have to blow it up. So still testosterone-fuelled.
 

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Wouldn't it be cheaper to have only 2 - 3 RS68 engines and rest of the required liftoff thrust provided by strap on boosters. Basically a modern version of Energia rocket.
 

Wishbone

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So... is this a dirt-cheap SSTO? Why has nobody told me about it before?
 

T.Neo

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So... is this a dirt-cheap SSTO? Why has nobody told me about it before?

I wouldn't call it "dirt-cheap". Cheaper than STS, but not... $100/kg kinda cheap...

It faces very few of the problems that your usual reusable SSTO concept faces... primarily, it does not have a TPS, or a means of landing without crumpling itself to smithereens, or major orbital manuvering systems, etc.

but fins could do the trick just as well... i guess...

Fins would add mass... they would also give the vehicle a bit of a Raygun Gothic look though. :lol:

Strapping large boosters onto this would be heavily overkill, unless one wanted to make it really manly and reconfigure it to lift something like 70 tons of LH2 to orbit in one shot... :hmm:

Wouldn't it be cheaper to have only 2 - 3 RS68 engines and rest of the required liftoff thrust provided by strap on boosters. Basically a modern version of Energia rocket.

That depends on whether the boosters, their propellant, the separation systems, and the ground handling infrastructure for the boosters, is less expensive than the 2-3 extra RS-68 engines.

The idea is that economies of scale and increasing experience with the system lowers costs with use, instead of limiting the system to a specific architecture.

Be nice if you could make it compatable with this:

Hmm... that is a pretty interesting concept, I'll keep it in mind. I'm trying to go for compatible with-as-many-things-as-possible though, which would certainly include something very similar to Fluyt, at least.

EDIT:
anyways - i love the concept, i had envisioned G42's regularly being assigned fuel-ferry for supporting interplanetary missions but this is more present-day, i think

Yeah, but the eventual goal is something that can provide propellant to my absurd fusion spacecraft... I think those are a bit more than present-day. :lol:

The idea here is that propellant is a bulk resource- it's rather cheap, it's low volume (in this case especially), and you need to ship plenty of it (several times the mass of whatever you want to accelerate). Thus the idea is some sort of bulk shipper, to leave the spaceplanes to cheaply ship passengers, supplies, and high-value items to orbit...
 
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Capt_hensley

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"The only real downside, is that it ended up looking like a feminine hygiene product"

Why not reshape the fairing and cap? Biconical?
 

T.Neo

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Well, the front of the LH2 tank is a compromise between pressure vessel and aerodynamics; I doubt that making it a cone would be a desirable option.

The nosecap is so small, relatively speaking, that changing its shape probably wouldn't do much asthetically.
 

Wishbone

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Out good Capt. must have been speaking tongue in cheek, the design shape may oscillate between feminine and joint hygiene products...
 

K_Jameson

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An interesting concept. Will be released on Orbit hangar soon?
 

fsci123

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I was beginning to start work on mine and then i searched this on google... But good ideal though... Did you figure out how adjust orbit without wasting fuel...
 

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T.Neo

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Did you figure out how adjust orbit without wasting fuel...

No. The propellant tanker is passive once it reaches orbit and attains a stable attitude. There are RCS thrusters onboard, but they only allow for very minimal attitude control.

A client vehicle either performs rendezvous with the passive tanker directly, or an orbital tug of some kind brings the tanker to a client vehicle or a dedicated on-orbit propellant depot.

An interesting concept. Will be released on Orbit hangar soon?

Hopefully it will be released onto OH sometime. I am currently working on it, slowly, but I have hit a snag with the animation of the sunshade. Since the sunshade might not be that important and because I sense it has a relatively poor geometry, I might leave it out until I've figured out a way to fix the problem.
 
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Wishbone

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The best sunshade is always pointing at the Sun, IMHO (have the same objective requirement with the NTR core tank).
 

Cras

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This looks really great. I am always in the market of adding a good orbital tank. Haven't had any success with the Energy Tank, and plan on doing some test runs with the Jumbo Tanker after using the Spacecraft 3 to DLL converter, but yours looks quite promising.
 

T.Neo

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The best sunshade is always pointing at the Sun, IMHO (have the same objective requirement with the NTR core tank).

Yeah. My idea was/is for a large circular shield extending from the nose section of the vehicle; the vehicle would then still be shaded even if it was only roughly aimed at the Sun. I guess I can still reduce boiloff slightly by pointing the nose (or the nozzles, though they could have a lower albedo) at the Sun... directly would be best, to reduce incident area as much as possible, but even a slight angle off will still result in less radiation hitting the vehicle.

Another issue is insulation. The figures I found deal with several layers of multilevel insulation; right now I only envision foam like that on the ET, and I'm not sure if MLI blankets could survive launch. Maybe a hybrid of MLI, foam, and highly reflective paint could be a solution.
 
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Capt_hensley

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Yeah. My idea was/is for a large circular shield extending from the nose section of the vehicle; the vehicle would then still be shaded even if it was only roughly aimed at the Sun. I guess I can still reduce boiloff slightly by pointing the nose (or the nozzles, though they could have a lower albedo) at the Sun... directly would be best, to reduce incident area as much as possible, but even a slight angle off will still result in less radiation hitting the vehicle.

Another issue is insulation. The figures I found deal with several layers of multilevel insulation; right now I only envision foam like that on the ET, and I'm not sure if MLI blankets could survive launch. Maybe a hybrid of MLI, foam, and highly reflective paint could be a solution.

Another solution, yet very costly, would be a mega cooling system. I'm facing the same issues with my Gateway station. The recycled ET's have a heat, and boiloff concern that, like yours, must be addressed.

Radiators is another possible solution, but you still will have to protect against direct sunlight heating.

A hybrid solution? yes but how do you ballance the system to create a high efficiency rate?, I hate physics...:facepalm:
 

T.Neo

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Well, the problem with that is that it increases mass and complexity; two things I'm trying desperately to avoid.
 

Wishbone

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I am not a materials expert, but I keep wondering if there's a way to add an outer layer of foam over the MLI, and shed it off in the exoatmospheric flight, with some light pyro contraption (a detonation cord?). Re - mega cooling. What is the timeframe that the tanker should stay in orbit? As a consequence, what should be the primary power supply? What is the figure of merit for this design? The FOM should drive your choices.
 

Capt_hensley

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Well, the problem with that is that it increases mass and complexity; two things I'm trying desperately to avoid.

Tell me about it. The Tank mods on Gateway are very weight intensive, and the cooling system is taken up on a seperate flight.

Does your fuel have to be supercooled, or could you use RP1, do you need to take up Lo2, or could you use water and a electrolisys system inflight?
 
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