Rockets launched from high altitude

kojikun · Post by **kojikun** » 2002-12-06 05:54pm

Does anyone here know how to calculate the amount of fuel needed for a small space craft (about the size of a jet fighter) to be launched from an altitude of like 40 miles? I'm trying to figure how large an envelope a balloon would need to be in order to lift such a beast, and conversely, how much the whole thing would cost.

Post by **Sea Skimmer** » 2002-12-06 06:30pm

I don't think any balloon can reach up over 210,000 feet with a payload, if at all. That's taking you into the Mesosphere and Ionosphere. Not much air to support one up there.

Asst. Asst. Lt. Cmdr. Smi · Post by **Asst. Asst. Lt. Cmdr. Smi** » 2002-12-06 08:20pm

What is the highest we could get a balloon with a payload anyway? How much fuel would it take from there?

Sienthal · Post by **Sienthal** » 2002-12-06 09:20pm

Interesting, though it looks like more trouble than it'd be worth...I'm waiting for the geostationary orbital elevator

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Post by **Sea Skimmer** » 2002-12-06 10:49pm

I believe very lightweight weather balloons have reached up to 130,000 feet, but that's about it. I don't think you could work it with a hot air balloon, the fuel and tanks would weight far too much. Helium would be required.

kojikun · Post by **kojikun** » 2002-12-06 11:13pm

Yes the balloon would be filled with helium (or if the risk is willing to be taken, hydrogen). 130 thousand feet is 24 miles, 210 thousand is 40. So I guess the launch altitude would be 24-40 miles. Anyone know how much fuel it would take to put the craft into orbit? I do know what the X-15 reached 67 miles from a launch altitude of 8.5 miles. The craft was 5 feet long and on launch weighed 32,000 pounds, so I'm assuming that if balloon launched it would have to weigh equally, possibly less because of the higher altitude. The majority of the CLIMB to 67 miles was unpowered, engines only fired for two minutes most and flights were 12 minutes long. So I'm thinking that a higher launch altitude could allow for the same vehicle to reach higher altitudes, possibly even LEO, for little launch cost (mostly the fuel and helium, which would be easilly made back by launching satellites and tourism).

kojikun · Post by **kojikun** » 2002-12-06 11:27pm

Oh, I would also note that the X-15's fuel was anhydrous ammonia combined with LOX. Theres also alot of "Extra" stuff i cant understand the purpose off, such as hydrogen peroxide and liquid nitrogen (maybe they were overclocking

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