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"The two propellants were extremely efficient" This is not particularly true. Hypergolic fuel mixes are less efficient than LOX/LH2 (which is nontoxic (exhaus
by jlgreco 13y ago
"The two propellants were extremely efficient"
This is not particularly true. Hypergolic fuel mixes are less efficient than LOX/LH2 (which is nontoxic (exhaust is water vapor) though still hazardous of course) and LOX/RP-1 (more or less nontoxic again. RP-1 is just fancy kerosene). The only real reasons to use them in first stages^ is that you can store them in the rocket (problematic with cryogenic fuels/oxidizers like LH2 and LOX since they will boil off over a short period of time) and the ignition system is simpler (not really a big deal).
LOX/RP-1 was actually used with earlier ICBMs like the Soviet R-7, the American Atlas. Storable hypergolic fuel mixes followed these, though now modern ICBMs are solid fuel rockets (storable, and safe for people on the ground).
Hypergolic fuel mixes have caused issues for non-military rockets too. During Apollo-Soyuz there was a leak of N2O2 into the Apollo capsule. Not a very good situation at all, but for that application they are really the best tool for the job. http://en.wikipedia.org/wiki/Apollo-Soyuz_Test_Project#Re-entry_and_aftermath http://en.wikipedia.org/wiki/Apollo-Soyuz_Test_Project#Re-en...
^ Hypergolic fuels are also useful in engines that you need to start/stop multiple times, and in upper stages that need to store their fuel for a while.
- arethuza 13y agoSeems like a good place to mention: "Ignition - An informal history of liquid rocket propellants" http://www.amazon.com/Ignition-informal-history-liquid-propellants/dp/0813507251 http://www.amazon.com/Ignition-informal-history-liquid-prope...
- icarus_drowning 13y agoAlso, if you're looking for a short, but surprisingly informative video on the matter, Scott Manley's "WTF is rocket fuel anyway" video is fantastic: http://www.youtube.com/watch?v=jI8TuufCp0M http://www.youtube.com/watch?v=jI8TuufCp0M
- mikeash 13y agoThis is a great read and I highly recommend it. I was greatly entertained despite no particular background in chemistry. There is a PDF available here, since it's a wee bit hard to get from Amazon: http://www.sciencemadness.org/library/books/ignition.pdf http://www.sciencemadness.org/library/books/ignition.pdf
- acurious1ne 13y agoSecond this recommendation. The author was a propellant chemist/raketenmensch and wrote about the subject with passion and humor. A pleasure to read.
- redthrowaway 13y agoIgnition also comes up regularly in Derek Lowe's "Things I won't work with" blog, which is highly entertaining in its own right. http://pipeline.corante.com/archives/things_i_wont_work_with/ http://pipeline.corante.com/archives/things_i_wont_work_with...
- arethuza 13y agoI first saw a reference to Ignition in the "Things I won't work with" entry on chlorine trifluoride - the stuff you can use to set fire to sand... http://pipeline.corante.com/archives/2008/02/26/sand_wont_save_you_this_time.php http://pipeline.corante.com/archives/2008/02/26/sand_wont_sa...