Offset aileron bellcranks

[Nev]

Has anyone experimented with changing the aileron bell crank angle as a means of further reducing adverse yaw ? I was thinking it would relatively straight forward to make a second set and try out. Any other ideas that people have experimented with ?

[Tailwheelflyer]

I'm not sure that could be accomplished through the bell cranks. One thing to remember, Bob told me this while talking with him a couple weeks ago, is that an airplane without a certain amount of adverse yaw does not slip very well. The less adverse yaw, the more control deflection and control force will be needed to get an effective slip.

[Nev]

One issue with increasing aileron differential is that crosswind handling may suffer if there's reduced drag from the downwind aileron. More important on a tailwheel aircraft than a nose wheel aircraft.

I haven't really used sideslipping in anger other than to try it. The flaps are pretty sizable and draggy and at lighter weights it's relatively easy to increase the descent rate just by lowering the nose. At heavier weights it may be more useful if needing to increase the descent rate.

[svyolo]

Offsetting bell cranks and/or the control horn can both be used to increase differential. Bob used 90 deg bell cranks, so he must have done it with the control horn offset. It might have clearance issues trying to get more up aileron. The pushrod might hit the "alien" hinge bracket.

[bearhawk2015]

I have considered doing this for a while. I’m pretty sure it wouldn’t be to hard to do. I just need to look at a Cessna or Piper bell crank to see what ratio of offset they use. I wouldn’t worry about slipping with offset bell cranks, the rudder is more than big enough to handle it.

[svyolo]

When I was into RC sailplanes, I think we used to use 50%. So the down aileron would only move 50% as far as the up side. The airfoils that they use were also flat bottom, or nearly so. That was a long, long time ago.

[Nev]

I have considered doing this for a while. I’m pretty sure it wouldn’t be to hard to do. I just need to look at a Cessna or Piper bell crank to see what ratio of offset they use. I wouldn’t worry about slipping with offset bell cranks, the rudder is more than big enough to handle it.

My thoughts too. Any idea on how it might effect crosswind handling ?

[bearhawk2015]

I think it would still handle crosswinds just fine. I know they’re not a Bearhawk but I have landed Pipers and Cessnas plenty of times in 25 knot crosswinds and they have differential ailerons.

[rodsmith]

Kevin D. (AZBearhawk272) has rigged Bearhawks with the aileron cross cable adjusted shorter to reduce adverse yaw. There is a thread titled "aileron rigging" started 1-31-2018 with good information.

[Nev]

Kevin D. (AZBearhawk272) has rigged Bearhawks with the aileron cross cable adjusted shorter to reduce adverse yaw. There is a thread titled "aileron rigging" started 1-31-2018 with good information.

Yes I've discussed this with Kev and made a mock-up of it on my workbench. Unfortunately when I purchased the aileron cross-tie cable it was a little too short to make that adjustment. Thinking I might just reorder one section of it in the correct size and try that.

Actually I just found Kev's reply here.

[kestrel]

Any other ideas that people have experimented with ?

I've been experimenting with the pedals on the floor. They seem to be quite effective. I'll report back after a have some more data.

[Dave Roberts]

Look at the drawings for the patrol belcrank. It is offset. He addressed that issue on the patrol.

[svyolo]

What does the Patrol list as the up and down angle. The 4 place lists 22 up, 17 down. It appears to be done by a bit of offset in the control horn on the ailerons. The bell cranks are 90 degree.

[Dave Roberts]

I’ll have to look at the patrol plans tomorrow, but I think the plans I have the bell crank is offset.