Pulse Detonation Engines Out of Favor?

Since the last time a Pulse Detonation Engine delta-winged supersonic aircraft was observed heading to California across land was in December 1999, perhaps the propulsion system has fallen out of favor.

It could be that this propulsion won't be brought back until manned space travel beyond low Earth orbit returns to the space program. An engineer at an air show in Arizona, who works at Edwards AFB for a defense contractor explained to me that PDE was not very efficient for use on aircraft.

originally posted by: BILL LOHMEIER
Since the last time a Pulse Detonation Engine delta-winged supersonic aircraft was observed heading to California across land was in December 1999, perhaps the propulsion system has fallen out of favor.

It could be that this propulsion won't be brought back until manned space travel beyond low Earth orbit returns to the space program. An engineer at an air show in Arizona, who works at Edwards AFB for a defense contractor explained to me that PDE was not very efficient for use on aircraft.

In the 1990s there was speculation that the "donuts-on-a-rope" contrails were made by a pulse detonation wave engine, but the first pulse detonation wave engine was not tested until January 2008 when a Rutan Long-EZ homebuilt aircraft was used as a testbed for it. In his 1993 book on the putative hypersonic spyplane with which the name Aurora became associated in the late 1980s and early 1990s, Bill Sweetman noted that low-speed pulsations by a rocket-boosted combined cycle engine are not in any way consistent with the behavior of a pulse detonation wave engine. Moreover, a March 1998 issue of the Popular Mechanics magazine contains a brief item under the "Tech Update" about photos of an SR-71 releasing streams of spherical puffs confirming that the "donuts-on-a-rope" contrails were in no way generated by a pulse detonation wave engine.