Alternatives to chemical rockets

[SargeRho]

11 minutes ago, sevenperforce said:

Any idea why not?

Possibly. One of the members of MSNW is working at Helion Energy, who are building incrementally better prototypes of pulsed fusion reactors, based on the design of the Fusion Driven Rocket. My guess would be that they've decided to just do that for now, and maybe develop the FDR as an offshoot.

Edited February 20, 2016 by SargeRho

[tsotha]

11 hours ago, Spaceception said:

Near term: Nuclear thermal rockets fueled by liquid Ammonia, Long term, VASIMR.

Why the order?  Ad Astra already has a functioning VASIMR engine which can be driven by solar cells for smaller applications, whereas nobody is even working on nuclear thermal.

[SargeRho]

13 minutes ago, tsotha said:

Why the order?  Ad Astra already has a functioning VASIMR engine which can be driven by solar cells for smaller applications, whereas nobody is even working on nuclear thermal.

NASA's working on NTRs, and the technology behind NTRs already exists, since a functioning prototype was tested *decades* ago.

[fredinno]

On 2/21/2016 at 11:52 PM, SargeRho said:

NASA's working on NTRs, and the technology behind NTRs already exists, since a functioning prototype was tested *decades* ago.

Yeah, but the amount of work is a lot less than ION, and the overall experience for any ION system is less. VASMIR is somewhat different than conventional ION, but I'm going to bet my a** it's 3x more likely for one to make a VASMIR tested in space than an NTR.

[fredinno]

On 2/20/2016 at 2:05 AM, Temstar said:

There is potentially something with that energy density - nuclear isomer. Weather or not you can actually trigger the isomer to release all their energy on demand is questionable though.

That's assuming the hafnium thing actually works.

 

On 2/20/2016 at 1:58 PM, sevenperforce said:

Any idea why not?

We haven't even mastered terrestrial fusion yet.

[SargeRho]

Just now, fredinno said:

That's assuming the hafnium thing actually works.

 

We haven't even mastered terrestrial fusion yet.

We have, actually, at least far enough to build a fusion drive. A fusion engine doesn't need to produce power, and can very well run in pulsed mode. What we haven't mastered is fusion power.

This here is the type of reactor one might use for a Fusion pulse rocket.

[PB666]

On 2/21/2016 at 1:37 AM, tsotha said:

Why the order?  Ad Astra already has a functioning VASIMR engine which can be driven by solar cells for smaller applications, whereas nobody is even working on nuclear thermal.

Vasmir without some sort of fusion power is limited basically to Earths or smaller semi-major axis. For orbits between earth and mars solar is questionable to power VASMIR and for anything beyond solar is completely useless for VASMIR, you would be better off just using small ion drives with low ISP once you get beyond mars (meaning small ion drives and large arrays of solar panels).

If it requires 50MW of power that means 10000 square meters of solar panels at 0.4 efficiency. If one gives 1kg per meter of panel that is 10,000kg of weigh just for the panel and at ISP of 17000 = 172000 Ve which means 200N of thrust which over the panels itself 20 millimeters per second less with Payload and VASIMR. For past earth you would need batteries and have to pulse.

 

 

[wumpus]

2 hours ago, SargeRho said:

We have, actually, at least far enough to build a fusion drive. A fusion engine doesn't need to produce power, and can very well run in pulsed mode. What we haven't mastered is fusion power.

This here is the type of reactor one might use for a Fusion pulse rocket. [picture deleted]
 

Any guesses of the mass of that beast is (including any needed power source)?  And how much thrust it generates?

[SargeRho]

8 minutes ago, wumpus said:

Any guesses of the mass of that beast is (including any needed power source)?  And how much thrust it generates?

From what I could find, 100-1000kw energy input. The thrust isn't all that high, according to Atomic Rockets, between 103N in low gear, and 13.8KN in high gear, with a specific impulse of  5140s. A ship using a low gear ship would have a wet mass of 90mt, and a payload fraction of 63%.

http://www.projectrho.com/public_html/rocket/enginelist.php#id--Pulse--Inertial_Confinement--Magneto_Inertial_Fusion