Invented by
Robert Goddard (1882-1945), a liquid-fuel rocket mixes a fuel and an
oxidizer in a combustion chamber (sometimes with the help of an igniter), and disperses the exhaust products of the
exothermic reaction through a
nozzle, producing thrust due to
Newton's Third Law. Goddard launched the first liquid-fuel rocket on March 16, 1926, from his Aunt Effie's farm. The flight lasted 2 and a half seconds; the rocket achieved a top speed of 60 mph (just shy of 110 kmh), a maximum altitude of 41 feet, and travelled
downrange 184 feet.
Because liquid
fuels can be stored separately from their
oxidizers, they safely store much more chemical energy than the same mass of any stable solid fuel. Common rocket fuels include just about any
flammable liquid. Common oxidizers are most nitric acids (esp.
IRFNA) and of course,
liquid oxygen. Goddard's first rockets used gasoline for fuel and liquid oxygen as the oxidizer. It may prove educational for
Americans to read about
Sergei Pavlovich Korolev and
Wernher von Braun, to get an idea of how much of
liquid-fuel rocket technology came from
Russia.