Hot Rod Job For SpaceShipOne

rwven writes "MSNBC is reporting that the engine on SpaceShipOne has been modified to provide more thrust, for a longer amount of time. Mainly, the Nitrous Oxide tank has increased in size to lengthen the amount of time before the dropoff of thrust when it goes from a liquid to a gas. Also reporting is Space.com."

Comments

Re:Wasting precious resources

[Rei]

Yeah. It's an easy fuel/oxidizer combo, but not very scalable. The specific impulse is just too low, and the nitrous tank too heavy. I do find it funny that they described hybrid rocket engines as not being "conventional rockets" ;)

And before some of the posters here start going off on a "Specific impulse isn't everything!" line, I'll add: It's not everything, but it is *incredibly* important. And if you can't have lightweight tanks to compensate for your loss of specific impulse (which you can't with nitrous), you're not going to scale. Plus, using a carrier launch, you're not going to handle the spiralling mass increase very well.

In short, this type of design, while great for getting the X-prize (it's very simple - self pressurizing, no liquid/liquid combustion, etc), would never scale to orbit. I'd like to see a good tow-launch LOX/subcooled propane rocket; that should be scalable and yet still take advantage of air breathing power to get to altitude, and wouldn't have to deal with LH.

What everyone hopes for are some of the things that are on the horizon, that have high ISP without the various tank mass or cryogenic limitations. For example, alane (stabilized aluminum hydride) hybrid boosters, which have an ISP that even with a weaker oxidizer like H2O2, nears LOX/LH's isp, and a very high density. Everyone in rocketry would like such a panacea; however, for now, everyone has different opinions on what is the best way to go.