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Re: starship-design: How to build a station.
> Ok, to try to be more constructive in this argument.
> How would you get a small craft into space?
> Well one option is hobbeist. Their are folks building and flying homemade
> ejector ramjets. The digging I attached seemed fairly comfortable with
> Ramjets/scramjets getting up to, maybe above mach 6. With a bit of work
> getting a ejector ram or pulse get to funding as a rocket in hard vac is
> so the engine weight penalty wouldn't be high.
A ram jet needs a rail launch,to get up to speed.
That saves a few kg of fuel.
> The bad nest is between there and the surface is hypersonic flight. Slight
> problems at that speed get nasty. You have a aerodynamics problem at 400 mph,
> you can probably nurse your homebuilt plane home. At mach-3 you and ship will
> look like you were run through a chiper-shredder. Also you need to make the
> hull out of high temp materials, especially for reentry.
How about a fractal wing? triangular pattern -- smallest shapes
hypersonic, middle pattern sonic, outer pattern sub-sonic.
But the exotic
> material used back when are now on the hobbest market. Pricy, but there.
> to mention new stuff like graphite composites that the 50's aerospace
> would have sold organs to get.) Get a hold of a good aerospace scrounger and
> you can find left overs at surprising prices. I've seen folks walk off with
> flight worthy titan engines and $.05 a pound scrap value.
Don't forget heat pipes,or open vapor cooling.
> How do you make a areo shape that can keep going in a straight line at those
> speeds? Steal! No blushing around. Order copies of hull info from a SR-71
> X-15 - or go talk to Burt Rutan who doing such work for Orbital Sciences.
> a hull shape that flew at those speeds and didn't try to fly sidewise.
> Large wing and flat bottom and belly flop in. Need some good high temp bottom
A lifting body is harder to design, but may not have any advantages
anymore over the simple design with better materials.
> If this is to much, piggyback on another group trying to build something like
> What about a space station?
> Well you can't ship it up in a craft able to carry 1/2 ton loads. You need
> then that to build a garage. Besides the economies of scale are terrible at
> that scale. Say 5 tons and the volume of a UPS truck.
With a 40:1 mass/payload ratio 5 tons is a 200 ton space/craft,
a bit large for a first time design. How about 2.5 tons... 100 ton
To make it simple
> and check most of it out down here, and disassemble it for up ship and
> REAL embarrassing to ship it up and find things don't fit.
yea for prefab.
> For the outer shell a inflatable bag with a doc port is good. Take it out,
> it out, and do the rest of your work in full air pressure. Spray a good
> of reinforced concrete in the inside for structure, shielding, and thermal
A side trip to the moon for concrete? way to heavy for lift from the
> Now you can bring up and outfit it pretty much like a normal building. Air
> processors can be adapted from marine and scuba recycling systems. need to
> brining up liquid ox to replenish, but that's not to hard. You can get most
> your water recycling by condensing it out of the air. Pump filtered brown
> out into reaction jets. Use their evaporation into vacuum for attitude
> thrust. Solid waste you need to bag and bring down.
> Power is a serious problem. Batteries and stuff are not good to have in a
> life-support area, and solar power systems need to be outside and maintained.
> Ship it up in prefab modules to socketed into dock points on the outside of
> docking module?
Solar panels are too expensive I guess. A small solar generator may be
here the limiting factor is not weight but bulk.
> How much would all this cost?
> Could be all over the map. Hobbest projects or ones done by small skilled
> can cost less then a hundredth of a industrial one. Industrial firms have
> estinated it would take them about $4-6 billion to build NASA $30-80 billion
> dollar station. So you possibly into the tens of millions in cost. Launch
> costs are a big factor. But if you have a decent launcher you can drop up
> costs so much you can save a lot of launching, and station design. Another
> cost is all the exotic junk on the station there to show off NASA's ability to
> make exotic junk (no I'm not kidding, I was on the program). If you just want
> some living space figure a few thousand a person for air and water processors.
> $10-$30,000? NOrmal inflatable tables and charrs (everything non flamible!!).
> Bifg cost is just launching it up. You probably looking a few tons per
> Now thats great compared to station, which is about 80 tons per person?
> For 70 people, assuming 8 tons per person (just a guess) thats 540 tons. At
> least a hundred flights of your 5 ton lifter. As a rought guess thats $1-3
> million dollars worth of fuel.
@ $.25 /lb fuel x 40:1 x 2,000 x 540 = 10.8 million
So you built your launcher for a extremely
> cost ($20-$40 million?), and can get folks to service it for free. You MIGHT
> be able to to get the stuff up there for $100 + a pound. If you can keep that
> up, you could get funding to turn your platform into a hotel, and actually pay
> your staffs.
> Ok, 100 flights for free servicing is rediculas, and a few industrial bargins
> for design and construction work and your $100 a pound jumps to $500 a pound
> real quick! Also the station construction and design costswern't covered, and
> its unlikly you can get this many REALLY helpfull friends willing to put in
> this time for free. Course if your looking ar a hotel complex, a firm might
> willing to drop a couple $billion to do it a bit larger and much less
Note with $.25/lb fuel cost and 40:1 ratio that is $10 lb or
20k per ton.
> For comparison, liquid oxygen/kerosene rockets typically
> get only 350 seconds of Isp. A ramjet typically gets 1,200-1,800 seconds,
That will drop the mass ratio down abit.
"We do not inherit our time on this planet from our parents...
We borrow it from our children."
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