> Guess why there are NO piston engined aircraft that use > the diesel > cycle?? Never say Never... Packard DR-980 Diesel Engine Packard DR-980 air-cooled diesel engine of 225 hp. Flight tested at Wright Field during the 1929-32 period in the XPT-8 trainer, it was the Air Corps first diesel aircraft engine. http://www.wpafb.af.mil/museum/engines/eng32.htm