jrl767

and often far from "fun" ... a lot of TSFC (thrust specific fuel consumption) tests, each test point approx 3 min of straight and level flight at a particular altitude, Mach number, and EPR (Engine Pressure Ratio; aka "throttle setting") with extremely tight tolerances on all ... I seem to recall a range of high cruise altitudes (27000, 31000, 35000, 39000) as well as some in the 10-15000 range, Mach (.74, .76, .78, .80, .82, .84, .86), and EPR (1.00 thru 1.20 in increments of .04); I also seem to recall needing 5-10 valid runs at each point to ensure statistically significant data, so if static pressure or ambient temp or wind varied by more than a whisker, the instrumentation engineer would call "Condition Off" and we'd have to restabilize ...

some engine operating characteristics tests, on the other hand, could get interesting ... at stable cruise, the pilot would pull one throttle to Idle and we would watch EPR decay ... when it got to the turnaround (several conditions, iirc ranging from about 0.65 to 0.85) he would push it back to max ... looking for a smooth response to throttle transients, which didn't always happen because the sudden change in fuel/air ratio could cause a compressor stall which was evidenced by a loud BANG and occasionally a flash of fire from the inlet and/or tailpipe

needless to say we did all the TSFC tests before doing the OpChar tests

pbd456

i did 20 in 7 days

lucycan

If I do, it will be at the hands of the ATL GA. Thanks!!!