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Thread: Mod. III Control Modification

  1. #1

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    Default Mod. III Control Modification

    I am contemplating installing the Kitfox Mod. IV, flaperon / flap control, conversion kit on the Kitfox, Mod.III (#1050) that I have recently resumed the building process on.

    Has anyone installed this kit on their Mod.III to date? Is there a noticeable difference in aircraft control, between the two systems? Or was this possibly a safety option, with no noticeable difference in control?

    At this stage, I am still sifting through the service bulletins and letters to see what componants I will need to order and replace, before actual building begins this go around.

  2. #2
    Senior Member Slyfox's Avatar
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    Default Re: Mod. III Control Modification

    I have the flaperon control on my kitfox. To be honest, I never use the flaps. Does this just give you the ability to have flaps? Like I said, I never use flaps, I have many other options for landing, like slipping, and full rudder with wings level to slow er down for landing. I like the lazy approach when landing the plane. Pull the power and land. If I need to slow the plane, I use slips, full rudder wings level just off the runway, or just bank er good and pull on the elevator on the base to final. I know I'm a nut.
    steve
    slyfox
    model IV 1200-flying
    912uls
    IVO medium in-flight
    RV7A-flying
    IO-360
    constant speed prop

  3. #3
    Senior Member cap01's Avatar
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    Default Re: Mod. III Control Modification

    the mod kit is listed in the kitfox catalog at the kitfox website . not much of a discription , youll have to call them for more info and see if it worth the money .
    chuck
    kitfox IV 1050
    912ul warpdrive
    flying B , yelm, wa

  4. #4
    Senior Member t j's Avatar
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    Default Re: Mod. III Control Modification

    Caballo, in a nut shell, the Model 4 flaperon control system has a 2:1 differential designed in. In a bank the travel on the aileron going up goes twice as far as the aileron going down. It counter acts adverse yaw and also helps maintain aileron authority when using flaps.

    I think there is no differential in the Model 3 aileron system which means you need to use more rudder to coordinate the turn.

    Tom Jones
    Classic 4 builder

  5. #5
    Senior Member Slyfox's Avatar
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    Default Re: Mod. III Control Modification

    In that case, I would put the new design on it.
    steve
    slyfox
    model IV 1200-flying
    912uls
    IVO medium in-flight
    RV7A-flying
    IO-360
    constant speed prop

  6. #6

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    Default Re: Mod. III Control Modification

    Thanks, these replies help a lot. When I get a complete list of componants I have to purchase, per the service bulletins and letters, I will finalize my decision on this.
    I like the additional control described by Tom. I am assuming this will make the Mod. III flaperon controls operate a little more like the citabria and super cub ailerons I am used to flying? Add a little rudder to initiate the turn then neutralize the rudder pedals once the turn has been established.

    Mark
    KitfoxIII (#1050)

  7. #7
    Senior Member Mnflyer's Avatar
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    Default Re: Mod. III Control Modification

    Hi Mark, the model 4 flapron mixer control system provides differential aileron which will reduce the adverse yaw, which for me is a non issue you just learn to use the rudder. The model 3 flaperon control does limit flaps to about 20 degrees which is more than enough for the Kitfox, one thing to consider if you intend to fold the wings any amount with the model 3 system there is no need to disconnect any of the control rods but with the model 4 system you have to disconnect the control rods to fold the wings. The model 3 benefits much more from enlarging the rudder/vertical fin area this will do more for flt characteristics than the differential aileron will ever do. I have a model 3 and have flown it more than 670 hrs and it is a good flying plane like I posted the best mod I did to it was to add a dorsal fin and increase the vertical fin area.
    Last edited by Mnflyer; 01-22-2010 at 11:44 AM.
    GB
    Flying a HKS Kitfox III and a Champ

  8. #8
    Administrator DesertFox4's Avatar
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    Exclamation Re: Mod. III Control Modification

    I admit to loving the way the model 3 flies. I did not care so much for the flapperon control mixer though. Lots more parts(strange shaped aluminum blocks) that could develop wear. Not a great trade off for having to unhook two rods to fold wings on the model 4 on up. Wear is always something to look for on any flight control system. The model 4 system seems much less prone to wear.


    Again, as our Kitfox fleet ages we need to be vigilant for maintenance concerns on our higher time aircraft. Let's keep that great Kitfox safety record intact and share information that is vital to that goal.


    DesertFox4
    Admin.
    7 Super Sport
    912 ULS Tri-gear


  9. #9
    Senior Member Mnflyer's Avatar
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    Default Re: Mod. III Control Modification

    Hi Steve, you are absolutely right in that the model 3 system has many joints and wear points and simpler is always better in my book, I guess if I were building a model 3 I would probably go with the model for system designers figure out way back in the 30's that differential aileron movement was a good thing, and since you have flown both the model 3 & 4 systems you know about both, and for me disconnecting the controls would be a non issue also as I only fold the wing every couple of years at the most. I really think that the model 4 was is an excellent plane the best of the original Kitfox line.

    On my plane I replaced the main pivot bolts in the mixer/control and went from plain AN bolts to MS or AN close Tolerance bolts these bolts are much stronger and are close tolerance thus reducing wear plus I coat them with grease and check them every 300 hrs or so.
    Last edited by Mnflyer; 01-22-2010 at 11:48 AM.
    GB
    Flying a HKS Kitfox III and a Champ

  10. #10
    Hallgrimur's Avatar
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    Default Re: Mod. III Control Modification

    To what purpose would you do this mod in the first place..?? What do you gain. Some of the Kitfox flyers commenting on this, I notice, never even use the flaperons.. So there is no experience there.
    I for one use them often on my older model for shortfield landings, to lower a bit the stalling speed, but mostly to increase visibility (lower the nose) on final appr. I need some 30 - 50 meters to land with or without the flaperons. Final appr. speed is then close to stalling speed. The problem with the older models like mine, with the smaller tail section is the increased control movements needed. > My advice, do something else to make your plane more safe or to have more fun flying.. To be honest!

    regards
    Hallgrimur

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