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I'm very interest in Orion nuclear pulse propulsion: the original project use ammonia as shock absorber gas, for open-cycle cooling and for propelling the pulse-units. Is it possible to project a version that use water steam instead of ammonia?
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The US Navy uses water brakes and high pressure steam to fling aircraft off of aircraft carriers. That catapult, or cat as we call it, slams into a water brake. It literally shakes the entire bow of a 100,000 ton warship. I slept just aft of the end of the cat's run (the water brake) and I can attest that it can knock you out of your rack.
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The US Navy uses water brakes and high pressure steam to fling aircraft off of aircraft carriers. That catapult, or cat as we call it, slams into a water brake. It literally shakes the entire bow of a 100,000 ton warship. I slept just aft of the end of the cat's run (the water brake) and I can attest that it can knock you out of your rack.
It's very interesting. Water is cheaper and easier to handle than ammonia: I'm sure that there was a good reason for why Orion's guys chose the latter, but I don't know it.
Last edited by Quaoar (2017-03-09 15:20:52)
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Ammonia is easier to vaporize at ambient temperatures. Just release the pressure. Similar to propane, but the pressure to liquify is lower.
GW
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
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Interesting fact. Fission products are about 1 million times more toxic than the combustion products of fossil fuels (mainly micron sized particulates and aromatic hydrocarbons). But they are released in 1 million times smaller quantities. So a fission bomb exploded in the Earth's atmosphere, exposes the global population to about the same toxicity as burning the equivalent energy value of coal. As most rocket engines burn rich, it is possible that pound for pound of payload delivered into orbit, an Orion may generate fewer pollution related mortalities. Hydrogen bombs do better still. But it doesn't matter: this is a problem of perception.
For this reason, some kind of nuclear thermal engine may be a better bet. A mechanical alloy of solid oxide fuel particles in tungsten metal tubes, would contain the radioactive nasty's even if this thing exploded on its way to orbit. If the vessel takes off from and lands at sea, there is never an issue with contaminating the land. Metal fuels can be taken to very high burn-ups as they tend to anneal at high temperatures and the fuel tubes can be vented allowing fission products to be removed after each flight.
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How does SpaceX's landable bottom stage technology change this equation. Lets say we had a giant reusable lower stage capable of boosting a nuclear upper stage into space, which can then nuke its way into orbit and beyond. Both are reusable!
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How does SpaceX's landable bottom stage technology change this equation. Lets say we had a giant reusable lower stage capable of boosting a nuclear upper stage into space, which can then nuke its way into orbit and beyond. Both are reusable!
Might be better to do it the other way round - a reusable nuclear lower stage and a lox-methane upper stage. That way, the nuclear payload is not at risk of burning up in the atmosphere and the mass ratio can be lower, since it is a booster stage. It could use desalinated water as propellant and could return to the same launch site off the coast. Would work well as a heavy lift launcher, maybe 1000te to LEO. That way, the nuclear ownership costs are spread over very large payloads.
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Tom Kalbfus wrote:How does SpaceX's landable bottom stage technology change this equation. Lets say we had a giant reusable lower stage capable of boosting a nuclear upper stage into space, which can then nuke its way into orbit and beyond. Both are reusable!
Might be better to do it the other way round - a reusable nuclear lower stage and a lox-methane upper stage. That way, the nuclear payload is not at risk of burning up in the atmosphere and the mass ratio can be lower, since it is a booster stage. It could use desalinated water as propellant and could return to the same launch site off the coast. Would work well as a heavy lift launcher, maybe 1000te to LEO. That way, the nuclear ownership costs are spread over very large payloads.
With a nuclear orion, you don't need an upper stage if your launch it from the ground, you would only use the chemical lower stage to reduce radioactive contamination at the launch site, and also atomic bombs would tend to destroy the launch pad and you'd have to build another one with each launch!
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