Aileron cables inside of wing strut

[svyolo]

I couldn't find anything in the builder manual or google or plans:

The wing struts are 7 1/2 feet long. That seems like a pretty long run for the aileron cables to be unsupported inside the strut. Has anyone thought about supporting it somehow? I thought about a tube, but I think it would cause too much friction. How about a fairlead in the middle?

I couldn't find a standard for the max length between cable supports or fairleads on a cable. 90" seems too much to me. Not the least of which would be wearing away the inside of the struts, at the same small area.

I have an 8" workbench. I will set up a 7 foot cable with 30 lbs of tension and see what how it behaves.

[whee]

I think your over thinking it. It’s not a problem. There are certified planes with longer runs of unsupported cables.

If you want to test it for your own curiosity consider using 26-28lbs of tension as that seems to be where the ailerons feel better (lighter) at.

[Mark Goldberg]

Actually - Bob has recommended 24-25 lbs for light aileron feel. And I agree with Whee - with so many Bearhawks flying with ailerons cables like this and NO issues - I would not try to reinvent the wheel. Sounds like a waste of time. However - it is somewhat common to have the cable want to rub on the upper end of the wing strut where the cable exits the strut. I have glued a rub block of hard nylon there, and other builders have some somewhat different things for the same issue. Mark

[Aero_tango]

Nylon block as well, secured with two 8-32 screw/nut...

[Gerhard Rieger]

Aero tango, hi, do you have the model A or Bravo wing? I will leave a photo at the end of the post with dimensions I need to make the cable through hole. I like the way you did yours.

[Aero_tango]

Hi Gerhard, I have the A wing. I’ve looked into my note and can’t find the information. I know that I had those…I’ll keep looking and let you know when I found them. Unfortunately, I can’t really go and measure them on the plane. It’s minus 23c today here..

[Gerhard Rieger]

Thanks Aero Tango. I also have the A wing, it will be much appreciated, no hurry. Have a great 2022

[svyolo]

Thanks for the responses.

[Archer39J]

Looks like that area is pretty well shrouded by the fairing, could you just not chamfer that corner of the strut? Wouldn't affect the strength of the strut at that point.

[Mark Goldberg]

Outside of the area where the wing strut end is - on my 4 place I "tapped" the very end of the wing strut with a hammer to get just the very edge of it to clear the cable. One side only. The other side I put a rub block. The plans call for a 3" pulley there above all this. It is perhaps helpful to use a 3.5" pulley if it helps the cable clear. Mark

[fairchild]

I was going to say --- a tiny pulley ? (at the end) it could be shielded from the wind there so it wouldn't make any more drag. I wouldn't complain about a fairlead at the 1/2 way point inside.
Mounting it might be tricky though.

[Bcone1381]

Nylon block as well, secured with two 8-32 screw/nut...

I would like to install a rub block at this same location. Is phenolic another acceptable material to use as a rub block for the aileron cable in this area? I have some phenolic sheet on hand.

[Archer39J]

I would like to install a rub block at this same location. Is phenolic another acceptable material to use as a rub block for the aileron cable in this area? I have some phenolic sheet on hand.

We use phenolic for spacers on aircraft monuments but never for any wear resistant uses, those get nylon. Funny enough we use phenolic "rubstrips" for galley carts and the like, but only because nylon of that size wouldn't pass flam (heat/smoke/tox). Specifically as it relates to AC control cables I recall seeing photos of cables destroying phenolic pulleys if they're not aligned properly. Based only on that I wouldn't think it would be suitable for that application. If others have differing opinions...

[svyolo]

The aileron cables go through a bunch pulleys/fairleads etc, and have a lot of connections. There are lots of opportunities for friction. I think my preference would be not to add anymore. I might put something to protect the strut/cable from the occasional contact, but I will do my best to keep it from rubbing all the time. I should be getting to this shortly also.

[whee]

Our Luscombe used phenolic blocks as wear blocks everywhere necessary. It was in great shape after 60 years so obviously it is fine to use if that’s what you have. We used nylon on the BH because that’s what we had. I think either is fine.

[Gerhard Rieger]

Can you help me with these measurements please.

[robcaldwell]

I did something very similar to this on my aileron control cables. Both my L/R control cables rest on flat nylon rub blocks at the inside bottom of the top wing struts. (I thought I had a picture but cannot locate it). I secured them with screws. It took me awhile to accept this as I thought I was hindering the "freedom" of the cables, but resolved this in my mind when considering this is no different than a fairlead nylon insert which redirects the travel of the cable to the rudder / elevator. it is just something that needs to be inspected annually for wear and potential replacement.

[Mark Goldberg]

Gerhard - I noticed the little nylon or plastic piece you made to insert into the wing strut to keep the cable from rubbing. That looks very useful and creative. Can you tell me how you made it? Maybe a picture of it out of the wing strut? Thanks. Mark

[Gerhard Rieger]

Hi Mark, this is not my aircraft, its a fellow Bearhawk builder on the forum, Aero_Tango. I also like what he has done, hence my question with his photo.

[Utah-Jay]

That rub block looks great, I saved that photo for when I tackle my wings