This photo is a Garrett YF104-GA-100 (Garrett ATF3) designed for use on the Teledyne-Ryan YQM-98A RPV for the USAF Compass Cope program.  Only five of these engines were ever built, two engines SN #16 and #17 for altitude testing at NASA Lewis Research Center.  Engine #17 demonstrated positive thrust of 40 LbFn at 100.000 feet MSL and Mach 0.8 during a go for broke run at the conclusion of testing.  This point exceed all other engines competing in the USAF Compass Cope program.    Three ATF3 engines were completed for the Teledyne-Ryan YQM98A RPV’s used in the USAF Compass Cope program, SN’s P-1, P-2, and P-3,  The five engines above (2 NASA Lewis test engines, 2 for Ryan YQM-98A’s, and one Ryan spare) are the only ones that could be mounted to the YQM-98A airframes as the ATF3 was completely redesigned in 1975.  All of these five engines were subsequently returned to Garrett at Torrance CA Site B and destroyed in a facility cleanup in the late 1980’s.  Several obvious differences between the current ATF3 engines and the Compass Cope engines are the Titanium Front Frame, lack of Surface Air Oil Coolers, Main Engine Mounts on the Crossover Duct instead of Midframe Assy, and the Gearbox/Oil Tank.

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