Question -- Forces on yoke?

[aatd 10]

Re; Yoke forces:

Does anyone here know, or can direct me to a resource, what forces (say in Nm) are on the yoke when flying any/all of the following aircraft at cruise speed?  This for the pitch as well as roll resistance.

- ATR 72

- King air (any version: 200 +) 

- Baron p58

I know, these are not likely something that most members would have laying around at hand!

Thanks all,

Brian

 

 

[aatd 10]

Clarification:

...I should have made clear, I am asking about forces at play on these Real World aircraft.

Again, thanks for any help should someone, on the off chance, know about these,

Brian

 

 

[orchestra_nl 971]

I expect that with proper trimming there would be no forces on the yoke.

[aatd 10]

Re; Trimming -- I agree.  What I am seeking are the forces involved when manually moving the yoke through its normal roll and pitch ranges.    I might end up having to contact the mfg'rs to see if they are willing to provide these data -- an iffy plan.  Thus my effort to see if they already exist somewhere on the net/

Thanks for your response though!

Brian

 

 

 

 

[SergeyPe 95]

26 minutes ago, aatd said:

Thus my effort to see if they already exist somewhere on the net/

The data for B737 is available (37+/-4 pounds for pitch, 12+/-3 pounds for roll at the yoke handle rim). I never saw it for the planes you've mentioned (except for +/- 52 kG for ATR 42/72 emergency CAP/ FO pitch channel disconnect).

[aatd 10]

Thank you Sergey,

The fact that you located it for the 737 gives me some hope I'll find them for some / all of the planes I'm searching on,

Brian

 

 

[SergeyPe 95]

Well, the most extensive piece of documentation on ATR that I've found so far is the Aircraft Handling Manual. It's very detailed (including the chapter on the flight controls); still no mention of the yoke actuation forces. Good luck anyway😀.

[C2615 322]

737's yoke is spring and hydraulically loaded, so it's quite fixed.

Other types with aerodynamic load might vary bit more, but it should have some range to be "acceptable" I guess.

[JRBarrett 3,142]

Almost all aircraft with hydraulically actuated or boosted control surfaces have an artificial feel system to give feedback to the yoke based on airspeed. The controls “stiffen up” as airspeed increases.

On an aircraft with strictly mechanical controls, this is a natural consequence of increasing airflow over the control surfaces. On a hydraulically-actuated aircraft, it usually is implemented with springs and some sort of variable bellcrank, whose center of rotation is shifted (either hydraulically or electrically) to offer increased resistance at higher speeds.

There is no “one” control force that applies in all situations. In a simple GA aircraft like a Cessna 172, you can easily move the ailerons and elevators to full deflection while on the ground with very little effort. At cruise airspeed, it requires just “pressure” on the yoke (very little actual movement) to effect a turn, climb or decent. That holds true for almost all aircraft. Most airliners also use some variety of “assist” in the roll axis with hydraulic roll spoilers, whose action is automatically controlled based on aircraft configuration and airspeed.

The 737 is somewhat unique in that the control surfaces are cable actuated, with hydraulic boost actuators. If all hydraulic pressure was lost, the airplane could still be controlled, although the force required would be extremely high. It would be like trying to drive a full-sized semi truck with no power steering.

I can check the maintenance manual for one aircraft I maintain (CRJ-200) to see what the normal control force for full yoke deflection of the pitch and roll axes would be with all hydraulics powered and the aircraft on the ground. The manual would not give deflection forces for any “in flight” scenario.

An aircraft like the A320 has no “force feedback” at all on the side stick controller. The control response to stick deflection varies with airspeed based on the control law of the FBW system.

Edited Monday at 02:17 PM by JRBarrett