Editing Pulse detonation engine (section)

== History ==
[[File:PDE-powered aircraft.jpg|thumb|300px|In-flight picture of the pulsed-detonation–powered, and heavily modified, [[Rutan Long-EZ]] on January 31, 2008]]

PDEs have been considered for propulsion since 1940.<ref>Hoffmann, N., ''Reaction Propulsion by Intermittent Detonative Combustion,'' German Ministry of Supply, Volkenrode Translation, 1940.</ref>

The first known flight of an aircraft powered by a pulse detonation engine took place at the [[Mojave Airport & Spaceport|Mojave Air & Space Port]] on 31 January 2008.<ref>Norris, G., "Pulse Power: Pulse Detonation Engine-powered Flight Demonstration Marks Milestone in Mojave," ''Aviation Week & Space Technology'', Vol. 168, No. 7, 2008, pp. 60.</ref>  The project was developed by the [[Air Force Research Laboratory]] and Innovative Scientific Solutions, Inc.  The aircraft selected for the flight was a heavily modified [[Scaled Composites]] [[Rutan Long-EZ|Long-EZ]], named ''Borealis''.<ref>''Borealis'' display poster text at Museum of USAF</ref> The engine consisted of four tubes producing pulse detonations at a frequency of 80&nbsp;Hz, creating up to 200 pounds of thrust (890 newtons).  Many fuels were considered and tested by the engine developers in recent years, but a refined [[octane]] was used for this flight.  A small rocket system was used to facilitate the liftoff of the Long-EZ, but the PDE operated under its own power for 10 seconds at an altitude of approximately 100 feet (30 m). The flight took place at a low speed whereas the appeal of the PDE engine concept lies more at high speeds, but the demonstration showed that a PDE can be integrated into an aircraft frame without experiencing structural problems from the 195-200&nbsp;dB detonation waves.  No more flights are planned for the modified Long-EZ, but the success is likely to fuel more funding for PDE research. The aircraft itself has been moved to the [[National Museum of the United States Air Force]] for display.<ref>[https://www.af.mil/News/Article-Display/Article/123534/pulsed-detonation-engine-flies-into-history/ "Pulse Detonation Engine Flies Into History"], ''Air Force Print News Today'', 16 May 2008, accessed 16 August 2008</ref>

In June 2008, the [[Defense Advanced Research Projects Agency]] (DARPA) unveiled [[Blackswift]], which was intended to use this technology to reach speeds of up to Mach 6.<ref name="wired">{{Cite news |title = Explosive Engine Key to Hypersonic Plane|first = Noah|last = Shachtman|author-link = Noah Shachtman|url = https://www.wired.com/dangerroom/2008/06/the-military-wa/|magazine = [[Wired (magazine)|Wired]]|publisher = [[Condé Nast Publications]] |location = San Francisco, California |date = 24 June 2008|access-date = 2009-06-27}}<!-- [http://blog.wired.com/defense/2008/06/the-military-wa.html ''Wired'' article] --></ref> However the project was reported cancelled soon afterward, in October 2008.