neufeld@physics.utoronto.ca (Christopher Neufeld) (01/18/90)
I was quite surprised to read on clari.tw.space that one of the shuttle's forward thrusters fired accidentally last night. You'd think this sort of thing would require pushing a few buttons, not just a passing whim in an on-board computer (if that's what it was). So, was the thruster which fired one of the ones used to break orbit? What is the fuel reserve on the shuttle? Are there similar thrusters on the stern, which would not deorbit the shuttle, but could burn so much fuel that the shuttle would no longer be able to break orbit? Does the shuttle always fly with the nose pointing along the orbit (ie. forward)? While we're on the subject of fuel, does the shuttle exhaust all its fuel before landing, or does it land with some fuel left in the tanks? Also, are the shuttle's thrusters powered by hydrogen-oxygen, hydrazine, or something else? -- Christopher Neufeld....Just a graduate student | neufeld@helios.physics.utoronto.ca | The meek can have the cneufeld@pro-generic.cts.com | earth, I want the stars. "Don't edit reality for the sake of simplicity" |
henry@utzoo.uucp (Henry Spencer) (01/18/90)
In article <1990Jan17.233050.3044@helios.physics.utoronto.ca> neufeld@physics.utoronto.ca (Christopher Neufeld) writes: >...one of the shuttle's forward thrusters fired accidentally last night... > So, was the thruster which fired one of the ones used to break orbit? A 'forward thruster' will be an RCS thruster, used for attitude control and minor maneuvering. I *think* they normally use the OMS for retrofire. >What is the fuel reserve on the shuttle? Are there similar thrusters on the >stern, which would not deorbit the shuttle, but could burn so much fuel >that the shuttle would no longer be able to break orbit? Fuel reserves are substantial, and although I don't have a shuttle plumbing diagram handy, it is normal to split such multi-thruster systems into two entirely separate subsystems, with separate tanks, each capable of doing any crucial jobs. This guards against massive malfuction in one subsystem. (For example, a thruster which cannot be turned off except by shutting down an entire subsystem -- it happened to Gemini 8.) > Does the shuttle >always fly with the nose pointing along the orbit (ie. forward)? No. Shuttle attitude is determined by what it's doing (i.e. whether the cargo bay wants to point in some specific direction) and a variety of other minor issues. > While we're on the subject of fuel, does the shuttle exhaust all its >fuel before landing, or does it land with some fuel left in the tanks? The latter. That's why the first ground crews around a landed shuttle are wearing protective gear -- the fuel and oxidizer are very toxic. >Also, are the shuttle's thrusters powered by hydrogen-oxygen, hydrazine, or >something else? Oxidizer is nitrogen tetroxide, fuel is one of the hydrazine family (I think it's monomethyl hydrazine but I could be wrong). They're toxic and corrosive and vile in other ways, but they don't need refrigeration and they're hypergolic (ignite on contact --> no ignition system). -- 1972: Saturn V #15 flight-ready| Henry Spencer at U of Toronto Zoology 1990: birds nesting in engines | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
serre@tramp.Colorado.EDU (SERRE GLENN) (01/19/90)
The type of hydrazine used by most (many?) rockets (the ones that use hydrazine, at least) is called "Aerozine-50", (this might be a TRW trademark) which is composed of 50% UDMH (Unsymmetrical DiMethyl Hydrazine) and 50% "regular" hydrazine (N2H4). This mix is used because it is more stable and has a larger liquid temperature range (I think). --Glenn Serre serre@tramp.colorado.edu