From: utzoo!decvax!cca!Tavares.Coop@MIT-MULTICS@sri-unix
Newsgroups: net.space
Title: Horsepower and rockets
Article-I.D.: sri-unix.1471
Posted: Sat May 15 13:40:32 1982
Received: Sun May 16 00:38:44 1982

Apples and oranges, but both relevant.  The specific impulse of a rocket
says how much "bang" you get per unit of mass of the propellant.  (For
example, a stick of dynamite and a long candle may put out the same
amount of energy, but the TNT has higher specific impulse.)  The
horsepower simply says how much total propulsion effort you get out of
the rocket.  You can double a rocket's horsepower by doubling the mass
of fuel in it (very roughly speaking) if the net effect is to double the
engine's burn time, all else remaining equal.  Horsepower is the same
beast as "total impulse" and consists of the same unit dimensionality as
Newton-seconds or watts.