Originally Posted by
BrandonSoMD
I think that deserves some clarification. I don't fully agree.
I'm a 30-year flight test engineer and am currently helping to rewrite the handling qualities flight test manual for the US Navy Test Pilot School. We focus more on military than transport aircraft, but we do test and fly 737-derivative airplanes (P-8A Poseidon and the C-40 Clipper) and the test methods are universally applicable.
Windup turns are done with set thrust, yes. Power is set as required to maintain the specified airspeed. What is being compared is the response of the airframe to increasing AOA or g at a fixed airspeed, and throttles are fixed during the maneuver to avoid contaminating the results with another independent variable. Several things can be learned from WUTs, including control force or deflection as a function of load factor or AOA, buffet characteristics as a function of AOA, and structural characteristics as a function of g.
While each test point is conducted at a specific power setting, the tests are typically conducted at a range of power settings. This provides a chance to assess the effect of power setting on the various aforementioned characteristics.
MCAS is (at the core) merely a trim application system, designed to reduce the control forces which develop at higher AOA and g with the new-and-repositioned engines. As such, it is a handling qualities difference that is definitely related to thrust line changes. Those differences would typically be revealed by a series of WUT test points. In this case, a WUT at high thrust would be worse, because of the increased pitch-with-power tendencies.
MCAS is there to increase, not decrease, stick force. That stick force either becomes non linear or reverses (need to ask Boeing) at high AOA due to the aero effect of the new engines nacelles. I'm not sure there are any thrust line changes to the handling of the Max. The engines were re-positioned forward and UP.