Flying Qualities

I've tried to replicate some stability and handling qualities tests using MSFS, for example:

I'll trim-shot the aircraft for a particular altitude and airspeed and then execute a pitch doublet on the stick control (free stick- without holding the input) and found some aircraft respond as expected (i.e. oscillating through the trim-shot with decreasing amplitude over time) while others are oddly statically neutral and fly off at the last pitch input.

There are other FTTs that the USAF and USN TPS manuals (available online) show that I've tried (e.g. accel/decel method) with some limited results. My interest is in being able to replicate as many of the FTT procedures as possible.

Force feedback is a problem since there is no feedback to the stick from the MSFS. I would consider this a 'fly by wire' type of an arrangement with no artificial feel. Also stick deflection (which I have not measured) may also be a challenge to replicate between simulator settings.

Spins are also a neat experiment to test using MSFS. Again some aircraft easily recover, some enter a rolling dive, while others you can not recover from a steady state spin within the simulator. Its a fun test, especially if you try and get the spin to flatten using rearward CGs (through the aircraft manager) or trimmed fully aft.

Is there any document or guidebook that just covers Flight Test Techniques without all of the theory, or at least a layman's explanation of the theory?

Thanks
 
Hello rpetty,

I'll trim-shot the aircraft for a particular altitude and airspeed and then execute a pitch doublet on the stick control (free stick- without holding the input) and found some aircraft respond as expected (i.e. oscillating through the trim-shot with decreasing amplitude over time) while others are oddly statically neutral and fly off at the last pitch input.

I don't believe you can actually test the "Stick-free" condition because the centering on your joystick is done by spring instead of aerodynamic loads which makes it basically always a "Stick-fixed" condition. I also don't believe the typical force feedback settings are accurate enough to simulate aerodynamic loads.

I believe the issue you are running into is controlled by Field 43 in Record 1101 in the AIR file.
That is where I would go look first and I am actually messing around in this area in the current AIR file I am working on.
This is what the AirED.ini looks like here:

41=86,00,---------- Pitch ----------
42=86,int32,<86h> Pitch Moment Coeff at AoA=0 (Cmo)
43=8A,int32,*<8Ah> Pitch Moment - AoA Rate (Cm_adot)
43h=Tendency to return to previous pitch
44=8E,int32,<8Eh> Elevator Control Factor (Cm_de)
45=92,int32,<92h> Trim Pitch Moment (Cm_dh)
46=96,int32,<96h> Pitch Damping Factor (Cm_q)
47=9A,double,<9Ah> Elevator Control due to propwash (Cm_de)
48=A2,double,<A2h> Pitch damping due to propwash (Cm_q)
49=AA,double,*<AAh> Trim Range (Cm_dt)
49h=Each 'click' of KB pitch trim is 1/1024 Range
50=B2,double,<B2h> Pitch Effect - Flaps (Cm_df)
51=BA,double,<BAh> Pitch Effect - Gear (Cm_dg)
52=C2,double,<C2h> Pitch Effect - Spoilers (Cm_ds)

The issue that I am running into is that I use both AirED and FDE and they are not entirely in agreement in this area.
The latest SDK also appears to be quite different from either of these configurations in the AIR file editors.

- Ivan.
 
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