"Everyman's Jet Engine" - Why Valveless Pulsejets? Light weight Because of their simple design and elementary welded sheet metal construction, modern valveless pulsejets are among the lightest propulsion systems ever designed. This is especially true if some form of stainless steel is chosen, since the high temperature strength of the metal allows very thin sheet to be used. The advantage of light weight for aircraft and watercraft powerplants is obvious; lightness also decreases engine mount stresses due to high "G forces" (due to maneuvering, hard landings, vehicle crashes and the like).