Why are jet engines' and rocket engines' tails shaped differently, one gets narrower as the other gets wider?
Asked by: Godzilla
The jet engine and the rocket engine have different
nozzles because they are harnessing two different
kinds of propulsion. The rocket engine is expelling
burning gases out of the back, and these gases are
still expanding when they are ejected. The open
cone shaped nozzle allows the outward expansion of
the hot gas to exert pressure on the rocket as it
flies. The jet engine, by contrast, does all of
it's burning inside the engine. With the exception
of afterburner, nothing is burning once it leaves
the tailpipe of the jet. The constricting nozzles
on the rear of a jet engine have much the same
effect as putting a conical nozzle on a fireman's
hose - forcing the same volume through a smaller
area must increase it's speed, and therefore,
allows the power of the engine to be more focused.
Answered by: Frank DiBonaventuro, B.S., Physics, The Citadel. Air Force Officer
'Our job in physics is to see things simply, to understand a great many complicated phenomena, in terms of a few simple principles.'