NOISY  HOBBY  OR  HOMELAND  TERROR? 
A small pulsejet going full roar 20 seconds after cold startup. 
The thin, bent stainless steel tube inserted into the tailpipe 
[secured in vise at left] is part of a gas velocity measurement 
experiment. The engine shown is a standard DynaJet running white 
gasoline as fuel. This is a fairly small engine, only 21 inches 
[535mm] long x 2.5 inches [64mm] maximum diameter and weighing 
1 lb [approx. 0.5 kg], but many homebuilt engines are much larger.
Some types of pulsejets can be homebuilt very simply and 
inexpensively, with minimal tooling and virtually no machining!
Photo Copyright 2003 Cottrill Cyclodyne Corp.