/sci/ - Science & Math

So I was thinking about the fission torch SRB concept that someone suggested a few threads back, and decided to work out how well it would actually work as a drive. As a continuous fission reaction drive with the criticality in the nozzle, the closest analogue would be the Nuclear Salt Water Reactor design proposed by Zubrin.

LEU (20% U235) NSWR stats:
> Ve = 66,000 m/s
> Isp = 6728
> mass flow = 195 kg/s
> thrust = 12.9 MN

Solid rocket fuels have a much higher molar mass than water, but the uranium is unchanged, so I'll say the Ve/Isp for our fission torch rocket, should be about half. Given that SRBs typically have lots of mass flow, this is already looking like a legitimate torch drive. Then I decided to see what this looked like at Shuttle SRB scale.

Shuttle SRB:
> Ve = 260 m/s
> Isp = 3364
> mass flow = 4615 kg/s
> propellant mass = 500 tons
> dry mass = 90 tons

Plugging some numbers together, and we get...

HEAVEN'S LANCE "RHONGOMYNIAD" FISSION TORCH SOLID ROCKET
> Ve = 33,000 m/s
> Isp = 3124
> 127s burn time
> thrust = about 300 MN (!!!!!!)

That is enough thrust at a high enough Ve to return a 100 ton payload on an Earthward brachistochrone trajectory from LOW JUPITER ORBIT if you have a plasma magnet sail to brake, and /sfg/ basically came up with it on a whim. I am in AWE.

>>12030761
>The propellant mix that would produce the greatest specific impulse for a rocket motor is sometimes given as oxygen difluoride and pentaborane
>Above 30 °C it can form explosive concentration of vapors with air. Its vapors are heavier than air. It is pyrophoric—can ignite spontaneously in contact with air, when even slightly impure. It can also readily form shock sensitive explosive compounds, and reacts violently with some fire suppressants, notably with halocarbons and water. It is highly toxic and symptoms of lower-level exposure may occur with up to 48 hours delay. Its acute toxicity is comparable to some nerve agents.
>Occupational exposure limits for pentaborane set by the Occupational Safety and Health Administration and National Institute for Occupational Safety and Health stand at 0.005 ppm (0.01 mg/m3) over an eight-hour time-weighted average, with a short-term exposure limit of 0.015 ppm (0.03 mg/m3).[12] The acute toxicity of pentaborane has caused it to be considered immediately dangerous to life and health, with a limit set at 1 ppm.[13]
>mfw

Paging the "things I won't work with" chemist guy.