Polywell for spacecraft

Discuss the technical details of an "open source" community-driven design of a polywell reactor.

Moderators: tonybarry, MSimon

icarus
Posts: 819
Joined: Mon Jul 07, 2008 12:48 am

Hydrogen sulfide hybernation

Post by icarus »


IntLibber
Posts: 747
Joined: Wed Sep 24, 2008 3:28 pm

Re: Polywell for spacecraft

Post by IntLibber »

MSimon wrote:
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.
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.
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.

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.

MSimon
Posts: 14332
Joined: Mon Jul 16, 2007 7:37 pm
Location: Rockford, Illinois
Contact:

Re: Polywell for spacecraft

Post by MSimon »

IntLibber wrote:
MSimon wrote:
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.
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.
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.

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.
Can you get such a launch vehicle man rated?
Engineering is the art of making what you want from what you can get at a profit.

IntLibber
Posts: 747
Joined: Wed Sep 24, 2008 3:28 pm

Re: Polywell for spacecraft

Post by IntLibber »

MSimon wrote:
IntLibber wrote:
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.
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.

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.
Can you get such a launch vehicle man rated?
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
Posts: 14332
Joined: Mon Jul 16, 2007 7:37 pm
Location: Rockford, Illinois
Contact:

Post by MSimon »

Astronauts get tested on rocket sleds that provide similar accellerations as well.
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.
Engineering is the art of making what you want from what you can get at a profit.

Mumbles
Posts: 51
Joined: Tue Nov 06, 2007 3:03 am
Location: Leonardtown, MD, USA

Electromagnetic Launch

Post by Mumbles »

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.
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...

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

MSimon
Posts: 14332
Joined: Mon Jul 16, 2007 7:37 pm
Location: Rockford, Illinois
Contact:

Post by MSimon »

Engineering is the art of making what you want from what you can get at a profit.

Mumbles
Posts: 51
Joined: Tue Nov 06, 2007 3:03 am
Location: Leonardtown, MD, USA

Mostly a comment on acceleration...

Post by Mumbles »

MSimon wrote:I like this technology for a maglev vehicle: ...
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...

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

IntLibber
Posts: 747
Joined: Wed Sep 24, 2008 3:28 pm

Post by IntLibber »

MSimon wrote:
Astronauts get tested on rocket sleds that provide similar accellerations as well.
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.
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.

Maglev also requires some significant masses in magnets, cryogenic systems to cool the superconductors, etc.

MSimon
Posts: 14332
Joined: Mon Jul 16, 2007 7:37 pm
Location: Rockford, Illinois
Contact:

Post by MSimon »

IntLibber wrote:
MSimon wrote:
Astronauts get tested on rocket sleds that provide similar accellerations as well.
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.
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.

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.

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.

IntLibber
Posts: 747
Joined: Wed Sep 24, 2008 3:28 pm

Post by IntLibber »

MSimon wrote:
IntLibber wrote:
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.
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.

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.

As to size - you build the tracks wider.

May I suggest a study of the system.
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.

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.

krenshala
Posts: 914
Joined: Wed Jul 16, 2008 4:20 pm
Location: Austin, TX, NorAm, Sol III

Post by krenshala »

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.

MSimon
Posts: 14332
Joined: Mon Jul 16, 2007 7:37 pm
Location: Rockford, Illinois
Contact:

Post by MSimon »

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
Engineering is the art of making what you want from what you can get at a profit.

choff
Posts: 2438
Joined: Thu Nov 08, 2007 5:02 am
Location: Vancouver, Canada

Post by choff »

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

IntLibber
Posts: 747
Joined: Wed Sep 24, 2008 3:28 pm

Post by IntLibber »

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
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.

Post Reply