LOOK,  MA -  NO  MOVING  PARTS!
Mechanically speaking, valveless pulsejets are the simplest internal-combustion engines ever 
- not even a reed valve to block explosion gases from leaving through the intake! In the 
Lockwood, there are no internal structures whatsoever [not even the flameholders found in 
ramjets]. There is also no fine machining required -- just sheet metal cutting, rolling and 
welding. Simplicity itself [but, how DOES Gary make that wonderful U-bend?].
Photo by Gary Robinson - Copyright 2002 Outwestjets