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Thread: Aileron Cable - is this Okay?

  1. #1
    Cubonaut875 SchulerJL's Avatar
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    Aileron Cable - is this Okay?

    I went flying last Saturday morning and as usual I had a couple of GoPros hanging on the plane. They are great to review technique etc. While I was watching the movie of the right wing, I noticed a lot of play in the aileron cable when I did a forward slip. It only seems to do it when I am in a slip. The first one has the most slop in the cable. I included the wing camera video on the first one as that was the steepest slip. On the video you can hear when I do a slip and watch the cables go slightly slack. The cables are new, had them replaced last January 2014. They do not feel loose on preflight inspection. Should this be a concern?

    https://youtu.be/BrIfH4ff1BM

  2. #2
    Bill Rusk's Avatar
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    No. Thats normal.

    Bill
    Very Blessed.

  3. #3
    cubdriver2's Avatar
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    Quote Originally Posted by Bill Rusk View Post
    No. Thats normal.

    Bill
    Or still too tight for some of us who like a sloppy stick feel.

    Glenn

  4. #4
    irishfield's Avatar
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    Point the camera in another direction and the "problem" will go away!

  5. #5
    fancypants's Avatar
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    Your cables look pretty tight. Took me a while to find a halfway decent photo, but this shows the "slop". Feels ok to me, but it is a little strange to see the cables flapping in the wind.



    I'm in the middle of replacing my cables right now, partly due to excessive slop, but mostly because the balance cable was OLD, and there was obvious wear on all four cables. I found it interesting that the cables I removed measured out almost exactly to the original Piper spec, 173-11/16" for the upper control horn cable (attaches to bottom of stick) and 167-15/16" for the lower control horn cable (balance cable above your head). So, no apparent cable stretch. The slop in the system seems to have been caused by worn pulleys and a bent pulley cage. Some of the slop could have been removed if I bottomed out the turnbuckles, but I'll feel better with new cables. We will see if the new Dakota Cub ball bearing pulleys allow cable tension to be increased without inducing too much drag.

    IMG_5403.jpgIMG_5408.jpg

  6. #6
    Cubonaut875 SchulerJL's Avatar
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    This is why I am a member - awesome replies. thank you. I thought it was a non event. There is very little slop in the cables - I like that - so I thought it was Okay.

    Fancypants - how in the world did you come up with that picture so quick?

  7. #7
    Bill Rusk's Avatar
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    Just as an aside, sometimes just one turn on the turnbuckle will completely change the "feel" of an airplane. Mostly in the ailerons, but even in the rudder and elevator to a lesser extent. Don't be afraid to experiment a little. What feels "best" to you will probably be different from the next guy. As Glenn says above.

    Bill
    Very Blessed.

  8. #8
    fancypants's Avatar
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    I don't need much of an excuse to start looking through old airplane pictures... it was a nice distraction during a boring conference call. Happy to help.

  9. #9
    Cubonaut875 SchulerJL's Avatar
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    Quote Originally Posted by Bill Rusk View Post
    Just as an aside, sometimes just one turn on the turnbuckle will completely change the "feel" of an airplane. Mostly in the ailerons, but even in the rudder and elevator to a lesser extent. Don't be afraid to experiment a little. What feels "best" to you will probably be different from the next guy. As Glenn says above.

    Bill

    Dan Byker replaced the cables last year. It had Stainless cables that were used during the restoration - after about 150 hours the stainless cables started to fray. I really think it handles better with the galvanized - or it was just set up better. Flies awesome now, I would have hated to change anything.

  10. #10
    cruiser's Avatar
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    I added DC ball bearing pulleys last year but I think the biggest improvement was made when I disassembled, cleaned and lubed the stick bearing saddles. Dried up grease is really draggy!

  11. #11
    texmex's Avatar
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    better with the galvanized

    Can't vouch for the handling. But I got very poor life span with the stainless. The galvanised ones seem to last much longer.

    I guess the stainless steel cables are good for low
    usage aircraft on water.

    For those that do a lot of Cub work (Mike, Steve etc) does that seem about correct?


  12. #12
    cubdriver2's Avatar
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    I'd tell you that my J4 has the original galvanized Navy tucked woven splice cables that piper installed in it in 1940 but you'd think I was crazy flying it on floats 100+ hrs a year.

    Glenn

  13. #13
    algonquin's Avatar
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    You wouldn't believe how many times I find a pulley that is sticking during annuals. I like LPS2 to free them up, when checking them don't just rock them turn them a couple revs both directions. Also make sure they move when the controls are moved, this is where you find worn pulley groves and/ or cable tension problems.

  14. #14

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    Most guys I have talked to agree that galvanized cables are the way to go, even for float ops. If you are primarily in a salt water environment that may be different. But stainless cables are prone to fraying and stretching (so i have been told). As
    Alginquin said, pulleys are more often the culprit with draggy controls

  15. #15
    skywagon8a's Avatar
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    My 2 cents,
    Stainless is more susceptible to chaffing and wear than galvanized. This is usually not a problem. The stainless cables on my 185 are nearly 40 years old without ever having any need to be changed. It's tensile strength is also less but is more than enough for our application. It is important that the pulleys be properly lubricated so that the cables do not drag through them. Dragging damages both the cable and the pulley which also changes the cable tension due to the reduction of the pulley diameter. The advantage of stainless is that it is more corrosion resistant than galvanized. Galvanized can easily develop rust in moist environments. This rust can be hidden inside leaving broken strands which can be unnoticed for years until the cable breaks.

    Galvanize solution: Soak thoroughly the galvanize cable in a can with some warm soupy paralketone (sp?) or some other suitable sticky corrosion preventative (like LPS-3). It comes out of the can rather thick so be sure to thin it. Kerosene works (gas does too). You want it to penetrate and coat all of the strands of the cable. Take the cable out of the can and hang up to dry before using. It gets sticky. It will last for years with this treatment.

    Cable tension: I will not question your desires for loose cables for light control pressures. That is your choice. However remember what the cables are supposed to do. In this case it is to move the ailerons. The ailerons need to be able to hit their full travel stops in all flight conditions. IE: Gusty crosswind approaches and landings. Do this: Have a friend hold the stick hard against the stop. This stop is under the floor at the rear stick. You grab the up aileron (be careful how you grab it, since it is more susceptible to fingers than to air loads) and pull it down. Can you pull it away from the up stop on the wing? If the answer is yes, the tension is too loose. Full aileron travel depends on the pilot being able to hold it against the stop with the in flight air loads pushing against them. IF the ailerons can be blown away from the up stops, you will not be able to hold the wing down as much as you wish in a crosswind take off or landing. Your ability to pick up a wing while landing in a gusty crosswind on short final will be compromised. How would you feel if you dragged a wing on short final because the ailerons did not hit their stops? Also and I hate to bring this up, if you loosen your cables, earn a hat, and your mechanic or IA didn't catch it, he could be liable. Lose his license, money, life style, etc., etc. Don't jeopardize your mechanic.

    The cable from the stick up the front strut to the aileron controls the up stop limitation. If you wish the aileron cable tension to be loose use the adjustment of the balance cable for this purpose. A loose balance cable allows the ailerons to fly up in flight (loosing some short field performance).
    N1PA

  16. #16
    cubdriver2's Avatar
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    I like my cables looooose. I moved or shortened the stops to give me full travel. Same with the rudder stops, if you have more then 3/8" between rudder and neutral elevator your going to have trouble turning on skis.

    Glenn

  17. #17
    behindpropellers's Avatar
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    Maybe your cables are straight and your strut is flexing

  18. #18
    RaisedByWolves's Avatar
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    We have been seeing the stainless wearing on the struts of the supercubs, where it goes through the fair lead, and rubs.

  19. #19
    skywagon8a's Avatar
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    Quote Originally Posted by RaisedByWolves View Post
    We have been seeing the stainless wearing on the struts of the supercubs, where it goes through the fair lead, and rubs.
    That does not surprise me. Those fair-leads should be of a materiel which will not wear stainless. Nylon, Delrin, what? There is a phenolic anti-chafe strip on the top of the bulkhead at the aft end of the 180/185 baggage compartment. IF the elevator cables touch they will wear there.


    ps. Perhaps loose cables allowing a lot of whipping around in the breeze is the cause of the wear?
    Last edited by skywagon8a; 04-14-2015 at 02:52 PM.
    N1PA

  20. #20
    skywagon8a's Avatar
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    Addendum to post #15 above,
    For some reason unknown to me, Piper designed the Cub with equal travel of the ailerons in both up and down directions. Most other types of planes have differential aileron travel, that is more up than down. Differential travel reduces adverse yaw. A down aileron has more drag than an up aileron thus when banking the nose will tend to yaw in the direction opposite to the desired turn. Less down aileron than up, reduces this tendency. More down aileron increases the stall speed on that wing. So what happens when a wind gust drops your wing on short final? Your reaction is to slam the stick full in the opposite direction. That encourages the low wing to stall rather than to lift up. Is this related to the "Moose Stall"? (Don't forget to use the rudder)

    I know you all know this, it doesn't hurt to remind us all.

    Why do I bring this up here? It is because there seems to be a desire among some to leave their aileron cables loose, either intentionally or unintentionally. The important most critical thing to pay attention to is that the ailerons MUST hit their up stops (not the stop under the floor, the one on the wing) with the stick hard over in flight. The cables stretch a little under load. If you want to leave the cables loose, let the ailerons ride away from the down stops. This may actually improve the aileron response. Don't get me wrong, I'm not encouraging you to do this. Only trying to make you more aware of the consequences.

    This equal aileron travel in both directions requires more aggressive use of the rudder to supplement the ailerons in picking up the wing. If you learned to fly in a Cherokee you will need lots of practice with your feet. Those pedals are not just a foot rest.
    N1PA

  21. #21
    Cubonaut875 SchulerJL's Avatar
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    Quote Originally Posted by skywagon8a View Post
    Addendum to post #15 above,
    For some reason unknown to me, Piper designed the Cub with equal travel of the ailerons in both up and down directions. Most other types of planes have differential aileron travel, that is more up than down. Differential travel reduces adverse yaw. A down aileron has more drag than an up aileron thus when banking the nose will tend to yaw in the direction opposite to the desired turn. Less down aileron than up, reduces this tendency. More down aileron increases the stall speed on that wing. So what happens when a wind gust drops your wing on short final? Your reaction is to slam the stick full in the opposite direction. That encourages the low wing to stall rather than to lift up. Is this related to the "Moose Stall"? (Don't forget to use the rudder)

    I know you all know this, it doesn't hurt to remind us all.

    Why do I bring this up here? It is because there seems to be a desire among some to leave their aileron cables loose, either intentionally or unintentionally. The important most critical thing to pay attention to is that the ailerons MUST hit their up stops (not the stop under the floor, the one on the wing) with the stick hard over in flight. The cables stretch a little under load. If you want to leave the cables loose, let the ailerons ride away from the down stops. This may actually improve the aileron response. Don't get me wrong, I'm not encouraging you to do this. Only trying to make you more aware of the consequences.

    This equal aileron travel in both directions requires more aggressive use of the rudder to supplement the ailerons in picking up the wing. If you learned to fly in a Cherokee you will need lots of practice with your feet. Those pedals are not just a foot rest.

    That is outstanding information. I never "joined the dots" with regard to this - makes sense - thanks

  22. #22
    RCharles's Avatar
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    I am replacing a stainless cable due to wear at the forward strut Fair-lead .What is the best way to connect the new and old cables together to pull the new one through the pulleys without removing the them ?

  23. #23
    fancypants's Avatar
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    RCharles: try heat shrink tubing, or the method shown in the post linked below. Removing the pulleys for that particular cable should be easy if it gets jammed up. Those pulleys are readily accessible by removing the covers on top of the wing, and inside the fuselage where the cable exits.

    http://www.supercub.org/forum/showth...l=1#post619711

  24. #24
    RCharles's Avatar
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    That looks like the way to go... with the safety wire , etc . Thanks

  25. #25
    www.SkupTech.com mike mcs repair's Avatar
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    Quote Originally Posted by RCharles View Post
    That looks like the way to go... with the safety wire , etc . Thanks
    heat shrink is all I've ever used... the KEY is to pull gently, and not yank if it gets stuck, sometimes ya gotta back up and try again...

  26. #26
    cruiser's Avatar
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    Quote Originally Posted by RCharles View Post
    I am replacing a stainless cable due to wear at the forward strut Fair-lead .What is the best way to connect the new and old cables together to pull the new one through the pulleys without removing the them ?
    Your making a lot more work for yourself than necessary, the most difficult part is disconnecting/connecting the cable at the rear stick. Unless you have a big hole in the floor, take the stick bearing saddles apart, raise the torque tube slightly for access, don't lose the shims. Clean and lube the saddles, clean and lube the pulleys, pull the cable thru the wing with anything long enough to reach. Done.

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