This photograph is highly instrumented ATF3 Development Engine #17 being installed into the NASA Lewis Research Center for additional high altitude testing.  The testing was a competition for the Teledyne-Ryan YQM-98A Compass Cope RPV.  Engine #17 incorporated all of the changes validated in Engine #16’s testing.  Engine #17 met all of the operational requirements at 60,000 feet MSL, but testing indicated the engine could operate at even higher altitudes.  As it turned out the ATF3 Engine #17 or the required facility pressure altitudes were NOT the limiting factors.  Ambient heating of the NASA Lewis Research Center ducting limited the facilities ability to produce the required cold temperatures to simulate the high altitude / low Mach conditions required by the Teledyne-Ryan Compass Cope operating envelope.  (Jerry couldn’t remember the actual altitude number, but if MY memory serves me correctly the maximum altitude where the NASA facility could simulate the required temperatures at was at or near 68,000 feet MSL).

Some upper limit points were controversial.  The NASA Facility was also running at its upper limits and they went to great lengths to operate it to our advantage but any small loss of control resulted in hugh simulation variations so some upper limit points may have been inaccurately measured.  All agree the upper limit of Engine #17 was set by the facility, not the engine.

After the tests were over the Air Force Contracts Officer told us ours was the only engine in the competition to reach the minimum Mach Number, maximum altitude and still have any thrust.  (The Garrett TFE731 was the only other engine able to run the minimum Mach 60,000 feet MSL point, but produced no thrust.  Other competitors could not reach that point.) 

The information and NASA photo’s on this ATF3 Online Museum is Courtesy of ATF3 Project Engineer (PE) Jerry Steele (Retired).  I hope to get more information from the Assistant Project Engineer (APE) (and performance engineer for this testing) John T. Huber (Retired).