"Apptech" wrote in message news:044701c879e2$4f00ee50$e701a8c0@y2k... > * evil liquid Hydrogen is a special substance used by rocket > engineers to make horrendously complex rocket stages that > are far far far volumetrically larger than one could > possibly imagine because the SG of LH is about 70 times that > of gaseous air BUT about 14 times less dense than water. Add > to that the complications of super cryo temperatures and > super topping cycle engines run at a pressure that only a > Russian rocket engineer could be happy with. The end result > is an overall performance that is arguably inferior to what > can be gained with the far far far less sexy LOX and kero. Actually, the Russians have built some very respectable LOX/kerosene engines. For example, the one used on Atlas V. I've heard it's doubtful that such engines could be produced as cheaply in the US, especially considering Russian manufacturing philosophies. Jeff -- A clever person solves a problem. A wise person avoids it. -- Einstein -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist