Polywell for spacecraft
Re: Polywell for spacecraft
On the contrary, if the launch pad is a vertical tube in the ground and you have a pool of LOX in the bottom, you would get a very nice sub-nuclear detonation impulse getting off the ground, should get you immediately to 3g acceleration, none of this stately rising slowly off the pad. About the same as a catapult launch, a little more energetic than you see in a ICBM silo launch.MSimon wrote:That is the way I see it too. H2 for SSTO. To make that work with reasonable safety I see using a maglev slingshot for initial acceleration. Dumping tons of H2 around a launch pad during lift off does not seem to be the wisest move.IntLibber wrote:
For high thrust what you would do is dump a lot of hydrogen through cooling coils around the reactor and use the heated hydrogen for thrust. This mode really would not be necessary for anything but launch and/or moving from orbit to escape velocity on time sensitive missions.
The advantage is that the annular ramscoop you use for ram-air augmentation doubles as a sabot during the launch impulse, and the impulse gives it enough initial velocity to start working once the impulse detonation ends.
Re: Polywell for spacecraft
Can you get such a launch vehicle man rated?IntLibber wrote:On the contrary, if the launch pad is a vertical tube in the ground and you have a pool of LOX in the bottom, you would get a very nice sub-nuclear detonation impulse getting off the ground, should get you immediately to 3g acceleration, none of this stately rising slowly off the pad. About the same as a catapult launch, a little more energetic than you see in a ICBM silo launch.MSimon wrote:That is the way I see it too. H2 for SSTO. To make that work with reasonable safety I see using a maglev slingshot for initial acceleration. Dumping tons of H2 around a launch pad during lift off does not seem to be the wisest move.IntLibber wrote:
For high thrust what you would do is dump a lot of hydrogen through cooling coils around the reactor and use the heated hydrogen for thrust. This mode really would not be necessary for anything but launch and/or moving from orbit to escape velocity on time sensitive missions.
The advantage is that the annular ramscoop you use for ram-air augmentation doubles as a sabot during the launch impulse, and the impulse gives it enough initial velocity to start working once the impulse detonation ends.
Engineering is the art of making what you want from what you can get at a profit.
Re: Polywell for spacecraft
good question. Obviously carrier launched aircraft deal with this sort of dynamic launch daily, however its a lot cheaper to destructively test cat launches on 10-100 million dollar aircraft vs multibillion dollar launch vehicles. Astronauts get tested on rocket sleds that provide similar accellerations as well.MSimon wrote:Can you get such a launch vehicle man rated?IntLibber wrote:On the contrary, if the launch pad is a vertical tube in the ground and you have a pool of LOX in the bottom, you would get a very nice sub-nuclear detonation impulse getting off the ground, should get you immediately to 3g acceleration, none of this stately rising slowly off the pad. About the same as a catapult launch, a little more energetic than you see in a ICBM silo launch.MSimon wrote: That is the way I see it too. H2 for SSTO. To make that work with reasonable safety I see using a maglev slingshot for initial acceleration. Dumping tons of H2 around a launch pad during lift off does not seem to be the wisest move.
The advantage is that the annular ramscoop you use for ram-air augmentation doubles as a sabot during the launch impulse, and the impulse gives it enough initial velocity to start working once the impulse detonation ends.
True. However, a gentler launch opens space to a wider range of population. Which is another reason why I like a horizontal launch at around 1 to 1.5 Gs.Astronauts get tested on rocket sleds that provide similar accellerations as well.
Engineering is the art of making what you want from what you can get at a profit.
Electromagnetic Launch
I would offer that the technology is there to support a larger electomagnetic launch capability, at least as a quasi-first stage for a space launch vehicle. The new EMALS (ElectroMagnetic Aircraft Launch System) is in test and will deploy on the next aircraft carrier. The same technology could be ramped up for a larger launch vehicle. Launching an oversized vehicle on a longer track would be a system modification, not a new technology...MSimon wrote:However, a gentler launch opens space to a wider range of population. Which is another reason why I like a horizontal launch at around 1 to 1.5 Gs.
BTW, it doesn't really start to be uncomfortable until 3-4 G's of acceleration (G_x - through the chest, not G_z - head-to-feet). And the configuration of the actual seat has a lot to do with comfort level, so that could be tailored to support a ~"gentler" feeling launch, as well...
Be Safe
Mumbles
I like this technology for a maglev vehicle:
https://www.llnl.gov/str/Post.html
http://en.wikipedia.org/wiki/Inductrack
https://www.llnl.gov/str/Post.html
http://en.wikipedia.org/wiki/Inductrack
Engineering is the art of making what you want from what you can get at a profit.
Mostly a comment on acceleration...
Yes, I had followed Inductrack for a while for ~stage 0 rocket launch. I wasn't trying to say that the current EMALS was the only technology out there, just that the acceleration forces, from my experience, wouldn't necessarily be in the 1 - 1.5 G range for comfort...MSimon wrote:I like this technology for a maglev vehicle: ...
I also think, in a possible future where electricity is plentiful (where could we get that? Hmmm...), we could build another layer of infrastructure just above our highway system (not necessarily physically above, just a more selective layer - between the hghways and the airways) that would have a common track with a series of standardized "sleds." These sleds would be chassis that would ride on and inductrack network that could carry cars, trucks, or modal transportation (containerized) cargo. With a series of land ports - near current shipping ports but also distributed across terra firma - individual sleds could be computer controlled to go, at quite high speed, wherever desired. Manned or unmanned. And if the cargo was an electric vehicle, it could feed off the sled and recharge on its way there. The first and last few miles would be under its own power (or picked up by contract carrier for containers).
It should appeal to the greenies, since you displace CO2 producing vehicle exhaust and can propel current combustion vehicles purely by electricity for a significant portion of long-distance trips. You could also displace a significant portion of short-medium range air traffic, since these single-car electric trains - what I called sleds - would not require the loading and boarding delays of modern air travel...
Now where can we get a plentiful source of low cost electricity... Anyone? Anyone? Bueler? Bueler?...
Be Safe
Mumbles
Horizontal launch, hm I dont think polywell will scale small enough for that. A polywell engine is going to be rather large. You would need a transport fuselage larger than a C-5 or Antonov.MSimon wrote:True. However, a gentler launch opens space to a wider range of population. Which is another reason why I like a horizontal launch at around 1 to 1.5 Gs.Astronauts get tested on rocket sleds that provide similar accellerations as well.
Maglev also requires some significant masses in magnets, cryogenic systems to cool the superconductors, etc.
The Inductrack magnet weight is 1/50th of the weight supported. And they are permanent magnets. Halbach arrays to be exact.IntLibber wrote:Horizontal launch, hm I dont think polywell will scale small enough for that. A polywell engine is going to be rather large. You would need a transport fuselage larger than a C-5 or Antonov.MSimon wrote:True. However, a gentler launch opens space to a wider range of population. Which is another reason why I like a horizontal launch at around 1 to 1.5 Gs.Astronauts get tested on rocket sleds that provide similar accellerations as well.
Maglev also requires some significant masses in magnets, cryogenic systems to cool the superconductors, etc.
As to size - you build the tracks wider.
May I suggest a study of the system.
Engineering is the art of making what you want from what you can get at a profit.
Well a 3 meter wiffleball means a reactor core of what? 5 meters diameter? Then you've got mountings, airframe, tps, and you are talking easily a 7-8 meter diameter fuselage for a single polywell engine, at a bare minimum. I would not be surprised if it went to 10 meters. The space shuttles fuselage is about 3 meters wide.MSimon wrote:The Inductrack magnet weight is 1/50th of the weight supported. And they are permanent magnets. Halbach arrays to be exact.IntLibber wrote:Horizontal launch, hm I dont think polywell will scale small enough for that. A polywell engine is going to be rather large. You would need a transport fuselage larger than a C-5 or Antonov.MSimon wrote: True. However, a gentler launch opens space to a wider range of population. Which is another reason why I like a horizontal launch at around 1 to 1.5 Gs.
Maglev also requires some significant masses in magnets, cryogenic systems to cool the superconductors, etc.
As to size - you build the tracks wider.
May I suggest a study of the system.
You'll have a big hydrogen tank, a small boron tank (Handling the boron is going to be an interesting exercise, hopefully we wont need a lot of it), with the hydrogen being heated by the reactor it can be exhausted in an annulus around an aerospike, and an air ram around it to do air augmentation thrust in atmosphere.
Since a C5 cargo compartment has an inner width of at least 5 meters, I don't think that would be a problem. I haven't been in a C17 (I left the USAF before I got a chance to load cargo into one) but I wouldn't be surprised if it was wider considering the C17 has a larger cargo capacity and isn't much longer of an airframe.
Pure boron is not very dangerous. It is the hydrides that are deadly. However the more hydrogen in the hydride the less deadly.
Decaborane is not too bad. B10H14.
http://en.wikipedia.org/wiki/Decaborane
Toxicity of boron:
http://www.npi.gov.au/database/substanc ... es/15.html
Decaborane is not too bad. B10H14.
http://en.wikipedia.org/wiki/Decaborane
Toxicity of boron:
http://www.npi.gov.au/database/substanc ... es/15.html
Engineering is the art of making what you want from what you can get at a profit.
I was worried that the coils would just about have to be made out of unobtainium, before RNebel explained the fusion product left through the cusps after gyrating inside the magrid. If the vacuum system was the only major obstacle left, it should also mean the design is just about there for space related usage.
CHoff
I didnt mean that it was toxic, as a proponent of boron gelled kerosene fuels, I know. What I meant was that its a solid or rather a powder, which is a bit different handling as a rocket fuel than a liquid.MSimon wrote:Pure boron is not very dangerous. It is the hydrides that are deadly. However the more hydrogen in the hydride the less deadly.
Decaborane is not too bad. B10H14.
http://en.wikipedia.org/wiki/Decaborane
Toxicity of boron:
http://www.npi.gov.au/database/substanc ... es/15.html