"Brian Gaff" wrote in message ...
Noting recent reports, it seems everyone wants Kerosene engines now. Could
some kind person explain why these are better? I thought hydrogen was the
way the world were going, and cannot quite see how these are supposed to be
better.

Fuel handling, for one. There's a whole sequence of tradeoffs, and
I'll defer to those more knowledgeable on which is "better" for a
particular application, but one advantage of kerosene is that it's
a fairly dense noncorrosive liquid at standard temperature and
pressure. The fact that it's liquid at STP means it doesn't need
pressurized or insulated tanks. Its density means the tankage can
be smaller than the tankage required for a similar weight of
liquid hydrogen. Since a most of a launch vehicle is
propellant/oxidizer tankage and propellant itself, it makes
sense to pay attention to the structural mass required in the
tanks. For some applications, the easier ground handling of
kerosene versus LH2 is very important.

However, liquid hydrogen has a significantly higher specific
impulse, meaning less fuel mass is required.

See
http://users.commkey.net/Braeunig/space/propel.htm
http://www.hq.nasa.gov/office/pao/Hi...d/propelnt.htm

--Rich