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Thread: Pober Junior Ace Heavy Ailerons

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  1. #1

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    Pober Junior Ace Heavy Ailerons

    I bought a Pober Junior Ace a while back and have found the ailerons to be somewhat heavy in flight. Could this be from "standard" ailerons?
    Last edited by pacerpilot; 11-14-2015 at 06:21 PM.

  2. #2

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    If the ailerons are reflexing that much in flight, they will certainly be ineffective and sluggish. What is the cable tension now?

  3. #3

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    Well, I don't have a tension gauge so my A/I buddy has been advising me.
    Last edited by pacerpilot; 11-14-2015 at 06:23 PM.

  4. #4

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    I am not familiar with the control system of that particular airplane, but I can suggest some obvious items to look at.

    A) I assume that the cables are 1/8" 7x19 and not stiffer types of cable. Yes? Smaller is bad.

    B) I believe that pulley diameters should be 35X the cable size for best cable longevity and flex.
    So ideally your pulleys should be the 4 1/4" ones for least resistance. You can go smaller but the resistance goes up
    and the cable life goes down.

    C) The lowest resistance pulleys are the ones with ball bearings. I believe that there are control system pulleys out there
    that have bushings rather than bearings. If you have that type, lots of lube might help.

    D) The "float' of the ailerons might be the result of the pulley brackets flexing. You should not need huge amounts of
    cable tension for the system to do its job. But you are getting slack from somewhere and from the description it is
    unlikely to be the cable if the proper cable was used. 7x19 control system cable should handle a 2000lb load.

    D) And finally, every once in a while we see an airplane where the cable between the ailerons, the balance cable, has
    been twisted around a cable that goes to the control stick or yoke. In the dark of the inside of the wing, more than
    one mechanic has made this mistake while snaking the cables into place. And as you add cable tension, resistance
    goes up since the two cables are rubbing and abraiding against each other.

    Use some webbing to tie the control stick into a fixed position, then have a friend gently push up on an aileron until you see the position that you observe in flight. Then go looking along the cable runs to see what is yielding or interfering.

    Best of luck,

    Wes
    N78PS
    Last edited by WLIU; 12-12-2012 at 02:11 PM.

  5. #5

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    It's got 1/8" 7X19 cable-per print. The pulleys are only 2" though. I've done the "hold the stick" thing and the whole system seems to absorb the flexure although it does take what we feel is a lot of force to simulate the in flight condition. I haven't noted any flex in the pulley brackets. I'll do a very close check of the balance cable run. Your suggestion makes sense about interference. Since this is a low time experimental maybe something is sawing in there. Something I have noticed is that the plane flies with a negative angle of incidence-at least at the outboard ends of the wings. It does this despite the "up" aileron condition. I'll check the cable runs and go from there.

  6. #6
    Richard Warner's Avatar
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    I presume that as you are tightening the cables to pull the ailerons down that you are loosebing the balance cable between the ailerons. I think that the idea that a cable is twisted around something in the wing is more than likely the culprit. That thing ought to be fast with the up aileron in cruise. LOL. I hope you find it. Almost nothing is worse than flying a lousy flying airplane.

  7. #7
    rwanttaja's Avatar
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    Quote Originally Posted by pacerpilot View Post
    I bought a Pober Junior Ace a while back and have found the ailerons to be very heavy in flight.
    Hmmm. To clarify, can you confirm the ailerons are heavy in flight, but not while stationary on the ground?

    If that's the case, I doubt it's a tension issue. It sounds like the leverage isn't right, or there's supposed to be balance area and there isn't. Or there is something flexing in flight, and adding a ton of friction. There was a fairly popular homebuilt ~30 years ago where the wings would flex in flight and clamp down on the aileron torque tube.

    Can you compare as-built vs. the plans to make sure all the control horns, bellcranks, etc. are correct?

    If the heavy ailerons only occur in flight, you need to simulate flight conditions on the ground while looking at it. Might be able to just lift the wingtip a bit and look close inside and see if anything is getting fouled.

    If worst comes to worst, I'd suggest adding some spades to the ailerons.

    Ron Wanttaja

  8. #8

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    Thanks for all the good suggestions and info. I've checked the cable tension, looked for interference, flexed the structure and looked for interference and, verified all the cables are on the pulleys etc. The airplane is built exactly to plan. I've been reluctant to intentionally "mis-rig" the ailerons because, as noted, that just chases the problem somewhere else. I'd still not have proper response. Just to confirm, the ailerons are only heavy in flight. The controls move freely on the ground. It takes considerable pressure to force the ailerons into their flight position on the ground. It seems to be an aerodynamice force causing the problem-and powerful one. That's why I mentioned wing wash. Are there any Pober drivers in the East Texas or Louisiana area? Maybe a comparison would shed some light.

  9. #9

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    Quote Originally Posted by pacerpilot View Post
    It seems to be an aerodynamice force causing the problem-and powerful one.
    Yes, that is true of most airfoils and you're probably losing a noticable amount of performance. But the problem is too much elasticity in your control linkage and/or not enough leverage to maintain/move the aerodynamic surface.
    Years ago I used to fly a friends Baby Ace and the ailerons were streamlined on the ground and in flight. I also don't recall them being all that heavy in flight.

    Perhaps you can email Mr. Paul for more suggestions?

  10. #10

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    Flying another Pober Jr. Ace is a good idea (or at least calling another owner and talking to him/her). Are the control horns at the stick and the ailerons the proper lengths per the plans? ... and are the throws of both the control surfaces and the control stick proper? Improper lengths will change the gearing ratio (and hence force feel). The Jr. Ace has a big, long wing, and roll inertia is high. Adding a different wingtip will also change the aileron forces. Personally, I find the cub ailerons to be heavy and slow ... including the clipped wing version.

    If you can wait until OSH, the person that works in the builders' workshop is an Ace owner/builder extrodinare. He may also be able to shed some light on the situation, too. I am very curious as I did the drawings of the original plans ... updated and converted from original Corben parts and drawings. I need to see if I can find a copy of the drawings laying around the house.

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