Boron availability

[belbear42]

Tulse wrote:

The element produced is He3. It could be used for dirigibles

Fusion-powered zeppelins that never need refilling — awesome!

If it was He3 you could make a fortune selling it to various science labs instead of blimp filling.
I thought focus fusion produced plain ordinary He4

[jamesr]

belbear42 wrote:

That is the worry I have as well. According to Eric’s simulation results in the Technical Paper 1 the maximum reasonably achievable ratio of (Xray + Beam) / Input is 1.57.

There seems to be a little error in this paper:
On the bottom of page 5, it says “Fuel: B10H1” Shouldn’t that be B11H1?

I think it means the B_10H_14 decaborane – which when sublimed into the moderate vacuum will begin to dissociate and the hydrogens get knocked off. The partially ionized plasma will then completely break up the molecules when the discharge goes through it.

[belbear42]

jamesr wrote:

That is the worry I have as well. According to Eric’s simulation results in the Technical Paper 1 the maximum reasonably achievable ratio of (Xray + Beam) / Input is 1.57.

There seems to be a little error in this paper:
On the bottom of page 5, it says “Fuel: B10H1” Shouldn’t that be B11H1?

I think it means the B_10H_14 decaborane – which when sublimed into the moderate vacuum will begin to dissociate and the hydrogens get knocked off. The partially ionized plasma will then completely break up the molecules when the discharge goes through it.

Even in that case, it’s a different kind of error, because B10H1 makes no sense in either way.

[Lerner]

Sharp eyes! Yes it is a typo–should be B10H14. Proofreading has never been a strength of mine, I’m afraid.

[Brian H]

The Tech Paper is put out and edited by Canada’s NRC, so they missed it too!

And I pointed out the He3/He4 switch above. Anybody who wants He3 will have to sift it out of moon dust! 😆 🙂 :cheese:

[belbear]

Brian H wrote:
And I pointed out the He3/He4 switch above. Anybody who wants He3 will have to sift it out of moon dust! 😆 🙂 :cheese:

Phew! You just saved NASA’s Ares program from obsolescence! 😆

[Brian H]

belbear wrote:

And I pointed out the He3/He4 switch above. Anybody who wants He3 will have to sift it out of moon dust! 😆 🙂 :cheese:

Phew! You just saved NASA’s Ares program from obsolescence! 😆
Nah. Even He3 fusion is a waste of time and money compared to FF p-B11 generators. But of course, once FF’s operating full blast, going to space (moon, Mars, asteroids) will be a piece of cake.

[belbear]

Brian H wrote: Nah. Even He3 fusion is a waste of time and money compared to FF p-B11 generators. But of course, once FF’s operating full blast, going to space (moon, Mars, asteroids) will be a piece of cake.

Not to mention the fact that we can have a probe transmitting from Alpha Centauri or Sirius in about the same time it took the Voyagers to get to the edge of our solar system.

[Tulse]

Brian H wrote: once FF’s operating full blast, going to space (moon, Mars, asteroids) will be a piece of cake.

I’m not sure that’s true — once in space FF may make technologies like VASIMR far more practical, but the big problem will always be getting into space. I don’t see how FF will significantly change the problems of launching to orbit, at least not without other major technological advances (such as space elevators or huge magnetic launch tracks).

[belbear]

Tulse wrote:
I’m not sure that’s true — once in space FF may make technologies like VASIMR far more practical, but the big problem will always be getting into space. I don’t see how FF will significantly change the problems of launching to orbit, at least not without other major technological advances (such as space elevators or huge magnetic launch tracks).

What do you think of a focus fusion powered turbojet/scramjet powered launch vehicle with a chemical LOX/LN2 upper stage glider (type X-33) to fill the gap from high-atmospheric hypersonic flight to orbit?

Fusion-generated electricity drives compressor fans (instead of a turbine) and fusion heated air (instead of fuel combustion) provides jet thrust. Everything fully reusable.

[Tulse]

belbear, in the system you describe the only thing that FF would be doing is providing an alternate power source. As I understand it, the problems with scramjets aren’t in that area, but instead in the engineering of the hypersonic air passage. Perhaps I’m wrong, though — someone else here may be more knowledgeable on this topic.

[Aeronaut]

belbear wrote:

I’m not sure that’s true — once in space FF may make technologies like VASIMR far more practical, but the big problem will always be getting into space. I don’t see how FF will significantly change the problems of launching to orbit, at least not without other major technological advances (such as space elevators or huge magnetic launch tracks).

What do you think of a focus fusion powered turbojet/scramjet powered launch vehicle with a chemical LOX/LN2 upper stage glider (type X-33) to fill the gap from high-atmospheric hypersonic flight to orbit?

Fusion-generated electricity drives compressor fans (instead of a turbine) and fusion heated air (instead of fuel combustion) provides jet thrust. Everything fully reusable.

The rocket equation makes it perfectly clear that the space elevator is the enabling technology for meaningful space exploration. My understanding is that raising around 50G$ is a far greater challenge than incrementally increasing the tether strength.

[texaslabrat]

belbear wrote:

I’m not sure that’s true — once in space FF may make technologies like VASIMR far more practical, but the big problem will always be getting into space. I don’t see how FF will significantly change the problems of launching to orbit, at least not without other major technological advances (such as space elevators or huge magnetic launch tracks).

What do you think of a focus fusion powered turbojet/scramjet powered launch vehicle with a chemical LOX/LN2 upper stage glider (type X-33) to fill the gap from high-atmospheric hypersonic flight to orbit?

Fusion-generated electricity drives compressor fans (instead of a turbine) and fusion heated air (instead of fuel combustion) provides jet thrust. Everything fully reusable.

If the power density of the fusion power sources were sufficiently high (in terms of MW/m^3 and/or MW/kg) , that’s definitely feasible from at least a basic conceptual point of view (ignoring the complexities of the actual aircraft and propulsion system design). A lot of optimization and miniturization of the fusion source will be necessary to make this kind of system do-able for atmospheric flight propulsion. By way of comparison, an F-16 in full afterburner is burning fuel at a heat-content-rate of over 300MW (~60,000 lbs of fuel/hour), so consider that as the bare-minimum starting point for how much power you are going to have to provide in order to be in the right order of magnitude. And I think you meant “LOX/LH2” upper stage, right?

[texaslabrat]

Aeronaut wrote:

I’m not sure that’s true — once in space FF may make technologies like VASIMR far more practical, but the big problem will always be getting into space. I don’t see how FF will significantly change the problems of launching to orbit, at least not without other major technological advances (such as space elevators or huge magnetic launch tracks).

What do you think of a focus fusion powered turbojet/scramjet powered launch vehicle with a chemical LOX/LN2 upper stage glider (type X-33) to fill the gap from high-atmospheric hypersonic flight to orbit?

Fusion-generated electricity drives compressor fans (instead of a turbine) and fusion heated air (instead of fuel combustion) provides jet thrust. Everything fully reusable.

The rocket equation makes it perfectly clear that the space elevator is the enabling technology for meaningful space exploration. My understanding is that raising around 50G$ is a far greater challenge than incrementally increasing the tether strength.

The rocket equation does not pertain to the type of solution that belbear has proposed as the fusion-powered plane would not be consuming a mass-fraction of fuel during the initial ascent/acceleration. For the “booster” phase, yes…but at that point the fuel needed is trivial once the air-“breathing” portion has brought the craft up to the altitude and speed that a scramjet flight regime can provide.

That said, I’m certainly not discounting the usefulness of a working space elevator 🙂

[Tulse]

texaslabrat wrote: If the power density of the fusion power sources were sufficiently high (in terms of MW/m^3 and/or MW/kg) , that’s definitely feasible from at least a basic conceptual point of view (ignoring the complexities of the actual aircraft and propulsion system design). A lot of optimization and miniturization of the fusion source will be necessary to make this kind of system do-able for atmospheric flight propulsion.

One of the “advantages” of conventionally fueled craft is that they get lighter as they travel. With a FF powerplant instead, all the weight is constant. I presume there is some crossover point where a specific fixed weight fusion generator is more efficient than than a powerplant running on conventional fuel that gets lighter over time. But it is not immediately obvious that such crossover point can be easily reached — my guess is the fusion plant in such instance would have to be very light relative to its on-the-ground, fixed instantiation.

And I’m still not convinced that there would be any major advantage to such a system. As I noted earlier, the real problem with most launch systems isn’t lack of power per se (at least not power on the scale that an FF device would generate).

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