Some of you have asked me what I think of SpaceShipOne. Here’s my thinking:
Thank God Someone Is Doing It
I’m happy that someone out there is pursuing private LEO tourism. LEO tourism probably is practical, and the tourism will lead to practical use in terms of creating transports.
Will there be risks? Sure—anytime you’re using a rocket, it could blow up. The risks are probably pretty small, but in the early tourism days, any vehicle’s going to be a developmental and not an operational vehicle. A developmental vehicle has risks that an operational vehicle doesn’t–and frankly, I’m not sure there’s such an animal as an operational space transport right now. Soyuz might be one, but I’m not sure if they’re still twiddling things with the system. I should know, but I don’t. STS/Shuttle is still developmental, and probably always will be. For that, you have a bunch of Congressional ass-clowns and Dick Frickin’ Nixon to thank for that.
The Concept Is Cool
I think the SpaceShipOne concept is a good one. Sure, it’s an X-15 all over again—tow a rocketship to altitude, drop it like a bomb, light the rocket, ride to space, glide to a smooth finish—but it uses a hybrid rocket motor, and I friggin’ love hybrids. Some people—my boss, for one, and it always causes an argument when he does!—call a hybrid a “throttleable solid”. As anyone who’s been around me during a viewing of Armageddon knows, “You can’t throttle a solid rocket, dammit!”
Brief Interlude Into Propulsion Terminology
Solid rocket: fuel and oxidizer are both solid, often mixed; light it and the surface burns. You can burn it like a cigarette, inside-out, or a combination. Thrust is generally related to amount of surface area burning.
Liquid rocket: fuel and oxidizer are both liquid, tanked separately, and pumped together into a combustion chamber. Some reactions happen without catalysts [hypergolic], some require sparks or heat. Hypergolics are fun to play with and, in my mind, preferable.
Hybrid rocket: one of fuel and oxidizer is solid, other is liquid. Typically the fuel is solid [fuel grain], and the oxidizer is liquid or gaseous. The classic hybrid is a through-tapped cylinder where you flow the oxidizer through the fuel grain. Most hybrids need an ignitor/heat supply. A hypergolic hybrid would be … well, it would be fucking cool as shit. [I could kill myself playing with one in so many amusing ways that I perish the thought.]
Hybrids are cool as hell because you can include them in the structure of your [disposable] rocket, much the same way that liquid rockets often use the pressurized tanks as structural members. Yes, this makes for fun structural calculations as you start to exhaust your fuel supply, but that’s what we have those weenies for!
The SSO hybrid uses N2O and HTPB—yep, laughing gas and rubber. The last hybrid I
played with fired was a clear acrylic with either N2O or NO–I forget which. It was a bench unit about a foot long, and if you had a high-speed camera, you could watch the flame propogate down the tube as it lit. Bad-ass.
Why Private Entrepreneurship is Important to Privatized Manned Spaceflight
Look, what we do in Manned Spaceflight in NASA just isn’t applicable to the average Joe Millionaire wanting to drop $500k on a 30-minute trip to space. STS is developmental and mission-specific; the US hasn’t developed a winged crew-to-space vehicle since the X programs. That’s forty years, folks.
Someone’s going to have to figure out how you do this economically. I think a two-bird approach like SSO is going to be the end result—mainly because Single Stage-to-Orbit is the pipe dream of the people who don’t have a fucking clue about propulsion. [Come on, if a bunch of ignorant Alabama kids can do the mass fraction calculations of SSTO spaceflight and see that you get 2-3% cargo at best on a back-of-the-envelope, no-iteration, liberal-as-hell calculation, then some Ph.D’d eggheads has to know it’s impractical.] I think a rocket-fired first stage is also impractical because of the risks and the ground clearance you’d need to rip one off; an airplane first will allow you to use major airports.
That someone to do something economically, though, is not NASA. NASA does nothing economically–we have all these standards to kill the profit line. They’re necessary for developmental vehicles, but not operational stuff.
People want to go to LEO. Someone with the bucks to sink in capital can make it happen. Maybe it’s Rutan and Co. But it’ll be someone.