Real life Hornet stick force

[markturner1960]

As title, does anyone know what the real jet stick force is in each axis ? Trying to set up my FFB joystick as accurately as possible......

 

Thanks

[DummyCatz]

The longitudinal stick spring force constant (KFS) = 7.0 lbs/in, and the stick has an aft travel range of 5 inches. So you'll get 35 lbs force at 5 inches stick travel.

Data source: NASA TM 107601.

Edited January 4, 2023 by DummyCatz

[Hulkbust44]

10 hours ago, markturner1960 said:

As title, does anyone know what the real jet stick force is in each axis ? Trying to set up my FFB joystick as accurately as possible......

 

Thanks

IIRC it should be a smooth 3lbs all around until alpha becomes a factor at 22 deg and modifies it.

[DummyCatz]

For the exact stick force per g of the Hornet, one can refer to the block diagram (albeit a PROM v10.1 one) from the NASA public paper in order to figure out how many stick input corresponds to the commanded g/pitch-rate/aoa. Specifically look for the inputs of the forward-loop integrator path and ignore all the other paths that are open-loop or belongs to the proportional path, simply because the integrator is responsible of eliminating the error between the stick command and the g/pitch-rate/aoa feedbacks.

The F-18 introduces AOA feedback when above 22 degs, and also pitch-rate feedback below 366 KCAS. So as to simplify the matter a bit, we assume a condition of AOA < 22, KCAS > 366, and also the aircraft is not hitting the g-limiter. Then the stick force per g can be inferred by:

7~8 * stick force / 7.0 = 3.5 * (normal load factor - 1)

So roughly 3.5 lbs per g. If the airspeed decreases below 366 KCAS, the pitch-rate feedback blends in and the stick force per g increases a bit. If the AOA increases above 22 degs, the AOA feedback blends in and the stick force per g increases significantly.

Credits to @Curly

 

Ref https://ntrs.nasa.gov/api/citations/19920024293/downloads/19920024293.pdf