Aileron Cable rubbing

[Tim213]

Hi all, I have an issue while trying to rig my ailerons. The cable rubs the top of the strut where it exits the strut toward the bottom of the wing. I spoke to Mark G about this and he gave me several good ideas. I was wondering if any of you may have had the same problem and if so, what your solution was. Changing the pulley size is one possibility but I don’t wish to purchase new pulleys if that’s not the fix. Any pictures anyone has would be helpful also. Thanks for any input.

[stinger]

Tim 213, I have a fix I used however I do not know what aircraft you are building. My solution may work for you I don't know. I moved my pulley outboard and up this fixed my problem. My plane is scratch built LSA. Stinger

[JimParker256]

His profile says he's building a 4-place.

[rodsmith]

My quickbuild 4 place wings had the opposite problem, cable rubbed the bottom of the strut. I modified the pulley brackets to move them 1/2 inch inboard. The easiest fix for you would be smaller pulleys, but that will only work if the cable is barely rubbing. Did you tension the cable to 15/20#s when you checked, that might make a difference.

[BTAZ]

I had to remake the pulley bracket for one wing(cable was fine for the other) to shift the pulley position to center the cable in the strut. Was a bit of a pain to get to the nuts on the front side of the spar for the pulley bracket but was enough access through the front spar lightening hole to get the job done.

[svyolo]

I don't know if you are A or B model. My B model it rubbed a lot. I wanted a 2" inch pulley but at over 30 bucks a pop I didn't want to swap parts to make sure it works. The pulleys for the elevator/flaps on the bottom of the fuselage are the same bolt size, but much smaller. 1.75 if I remember right. They work OK. I would still prefer a slightly larger one but I couldn't find the diameter I wanted.

[Aero_tango]

In my case, cable wasn’t actually rubbing, but very close to the strut. In order to prevent any chafing,I installed a V shaped piece of nylon...Mike.

D07F3668-795D-49C4-871C-79332F74CA3B.jpeg

[Pbruce]

Mike Silvernagel from Bearhawk Canada told me to prevent the issue by installing a 1/8” aluminum shim between the wing fitting and the bottom of the strut. I think in the past, most guys were squashing the strut onto the fitting and then bolting, but Mike said the 1/8” spacer would do the trick and should be less work than flattening the strut. In the picture provided by Aero Tango above, it looks like he has the 1/8” shim on the bottom. Mike’s (and mine) are QB Patrol kits of recent vintage, so it might be different on yours. Maybe the shim needs to go on the top, or thinner ones top and bottom. I haven’t got that far yet on my plane.

[svyolo]

On my B model it was worse than "rubbing", and it was symmetrical on both sides. Bob approved the much smaller pulley.

[Aero_tango]

Yes, I do have shims between the struts and wing fitting. One on top and one on bottom. mike

[stinger]

I think some of us are reading Tim 213 message wrong and perhaps me. Cable touching inside of wing strut bottom surface at wing attach location. Large pulley relocated out board raising cable as required to achieve clearance . New support spanning across from top to bottom of spar and attaching pulley bracket providing clearance . Good Luck Stinger

[svyolo]

Yeah the new support would fix it too. I would kind of prefer that as I would rather use a larger pulley to reduce friction (the aileron cable runs go through a lot of friction increasing bits). The cable is only turning about 30-40 degrees or so.

[Tim213]

Thanks everyone for all the input. I have the QB 4 place with the Bravo wing. My wing was already completed and mounted when I encountered this issue.
So some of the excellent ideas were not viable for me. Mark G told me others have had the same issue and gave some suggestions that several of you also suggested. I tried installing a smaller pulley but I too found the 1.755 diameter a bit two small after buying two of them. I could not find another pulley larger except the 3 inch I started with. I made a delrin block like aero tango and found that with it and just slightly enlarging the hole in the wing, the angle was now good for the original pulley. Everything operates smoothly now. Thanks for all the help.