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STT757
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Thinking Beyond The Shuttle

Wed Feb 12, 2003 12:34 pm

From the NY Times, requires FREE registration to view.

<http://www.nytimes.com/2003/02/11/science/space/11OTHE.html>
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gotAirbus
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RE: Thinking Beyond The Shuttle

Wed Feb 12, 2003 1:01 pm

An excerpt from the NY Times newspaper (science section)

A Lifeboat for the Space Station

Contractors are competing to develop an "orbital space plane," above, within a decade. It would supplement the space shuttle and incorporate many design improvements.

Reinventing the Skin

Scientists want to develop metal tiles to guard against extreme heat at re-entry. The brittle ceramic tiles used now are vulnerable to debris and hard to manufacture and fasten



The shuttles were to have been museum pieces by now.

Instead, the remaining three -- Atlantis, Discovery and Endeavour -- will be the backbone of the American space program for another decade, possibly two. But the delays do have a silver lining. The design of a replacementcraft to be selected at the end of the decade will be able to include previously unavailable technologies like advanced engines and alloys that can withstand re-entry temperatures.

In the short term, NASA would like to supplement the shuttles with a simple vehicle that would be a ferry to take astronauts, but not cargo, to the International Space Station. Long-term alternatives, including space elevators, are limited only by imagination. At least until testing begins...
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GDB
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RE: Thinking Beyond The Shuttle

Wed Feb 12, 2003 6:02 pm

Yes, use a simpler, cheaper to develop and use than the shuttle, a smaller spaceplane launched by one of the new generation of expendable launcher now entering service, after 'man rating' it.
For cargo, either the 'Shuttle-C', or something new, using SSME's and SRB's, to speed development at a reasonable cost.
 
POSITIVE RATE
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RE: Thinking Beyond The Shuttle

Wed Feb 12, 2003 6:43 pm

Just a query. Would the shuttle be able to attain orbit if it was carried aloft by the 747 shuttle carrier to an altitude of say 45,000 feet and then seperated, shuttles 3 main engines are then ignited and it flies to LEO. Would this be possible?? Do the shuttles 3 main engines alone have the power to get into orbit from altitude?, say if the shuttle had a bigger internal fuel tank or something?
 
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PW100
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RE: Thinking Beyond The Shuttle

Thu Feb 13, 2003 4:34 am

@Positive rate

I don't think your suggestion is feasable.
The main problem with reaching orbit is not as much the altitude [250+ km], but more the speed required to maintain orbit [32,000 km/h+].

I believe that the shuttle combination weighs in at something like 3 million pounds on lift off. More than 85% of that weight is fuel [feel free to correct me if you might have more specific data]. All that fuel is required to accelerate the shuttle to the required orbit speed. Higher altitudes require increased orbit speed, thus more acceleration, thus [much] more fuel. Remember that velocity energy is:
= 0.5 x mass x velocity x velocity [velocity squared]
= 0.5 x mass x 8,888 x 8,888
= mass x 39.5 MN [Mega Newton] [mass in kg]

Altitude energy is:
= mass x altitude x gravity
= mass x 250,000 x 9.8
= mass x 2.4 MN

I assumed orbit speed @ 32,000 km/h [= 8,888m/s] @ 250km [= 250,000m]. Not sure if this combination is correct, but it should be quite close.

So a total of 42 million Newtons are required to get every kilogram [2.2 lbs] into a 250 km circular orbit.

If you would lauch a shuttle type vehicle from a 747 type vehicle, the speed gain [250 m/s --> 0.03 MN x mass] and altitude gain [13,700 m --> 0.13 MN x mass] is superficial, so you'll need to carry maybe 2.5 million pounds of rocketfuel to 45,000ft to get a shuttle into orbit . . . not likely!

PW100
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transswede
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RE: Thinking Beyond The Shuttle

Thu Feb 13, 2003 5:15 am

Just a query. Would the shuttle be able to attain orbit if it was carried aloft by the 747 shuttle carrier to an altitude of say 45,000 feet and then seperated, shuttles 3 main engines are then ignited and it flies to LEO. Would this be possible?? Do the shuttles 3 main engines alone have the power to get into orbit from altitude?, say if the shuttle had a bigger internal fuel tank or something?

Not a chance. Do you see how large the liquid fuel tank is? An aircraft-launched shuttle would need a much bigger tank, since it would not have the massive power of the solid boosters to give it a start into orbit. And there is no aircraft on earth that could lift that mass.

One could design a newer smaller shuttle, however, and it would be possible in theory.

The design firm in Russia that developed the Buran shuttle came out with just such a concept a few years ago, but due to budget issues, nothing has happened with it. The design was/is called MAKS, and was to be launched from a An-225: "http://www.buran.ru/htm/molniya6.htm">http://www.buran.ru/htm/molniya6.htm

 
srbmod
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RE: Thinking Beyond The Shuttle

Thu Feb 13, 2003 9:36 am

What they need to do is to develop a next generation Shuttle that uses the best cutting edge technology we have (I'm talking about stuff still being developed in labs at MIT, GA Tech, Cal Tech, and so on). The elements of the current Shuttle are of 1960s-1970s vintage, they were the best they had at the time, and they could have went further with the exsisting technology if the funds were there. As for an "orbital lifeboat" why not dust off the old USAF "Dynasoar" design?
src=http://www.worldspaceflight.com/america/images/dyna-soar.jpg>
src=http://www.worldspaceflight.com/america/images/titan_dynasoar.jpg>
 
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RE: Thinking Beyond The Shuttle

Thu Feb 13, 2003 1:33 pm

Yeah ok i didn't think that would be possible. That method would be ok though for a sub-orbital flight which is pretty useless though.

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