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Thread: Model IV-1200 factory tube landing gear alignment discussion

  1. #1
    Senior Member GWright6970's Avatar
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    Default Model IV-1200 factory tube landing gear alignment discussion

    I have done a search on here and in the internet regarding toe in and toe out. I checked my gear out per the excellent photo procedure on here, and found that my 1993 factory tube gear has BOTH sides with a toe in of about 1/2 inch to the aircraft center line, on 8 inch wheels and 21 inch Nanco tires.

    There are at least 3 of us builders in search of your experience and knowledge!

    Before I embark on disassembly and attempting to bend these axles, I wonder just how necessary this is. I can put up with the tire wear on the outsides. My questions revolve around if people are successfully landing aircraft with this much toe in, or any amount of toe in? Did you ever measure the toe in loaded, and in the 3 point attitude? Have those with positive camber (tire top is outward from the fuselage) had to ever adjust the camber also? How did you successfully correct the toe in or camber? Did bending the axle result in having to make modifications to the brake calipers, etc?

    It is my hope to have this thread be dedicated to factory tube gear experiences. Thank you!

    FYI.. my Kitfox is now registered, and after I address this issue, I will be proceeding to the Airworthiness Certification process... super close!
    Grover Wright
    Flying a KF IV-1200
    ROTAX 912UL

  2. #2
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    Default Re: Model IV-1200 factory tube landing gear alignment discussion

    Here is my take on it. If you are running right down the runway straight and level, then the tires will be scrubbing themselves off more or less the same amount with the toe in you have. But then you start a swerve to the right, weight will shift to the left wheel somewhat, and maybe the left wing goes down some as well. Both of those things will add more weight on the left wheel, and less on the right wheel. Where is that left wheel pointing (considering the toe in you have)? I would say it's trying to steer you more into the swerve rather then neutral or the other way, which toe out would do. That's why I would say neutral or just a slight bit of toe out is the way to go. I'm no expert, but like everyone else, I have an opinion, and this is it! :-) JImChuk

    PS when I measure the toe in/out, I make a mark in the center of the tires, and measure off that mark when it's straight ahead to a center line or the other tire. Then rotate the tires back 180 degrees and measure from the same mark again. That should be way more accurate then measuring off the sidewall of the tires.

  3. #3
    Senior Member GWright6970's Avatar
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    Default Re: Model IV-1200 factory tube landing gear alignment discussion

    Jim,
    Thank you. I agree with all of your response. I measured as per your procedure, from center of tire to center of aircraft line that was determined by a set of plumb Bob's off the center of the prop, and the tailwheel spring attachment bolt.

    I wonder what those who are flying with toe in can add to this discussion?

    Thanks Jim!
    Grover Wright
    Flying a KF IV-1200
    ROTAX 912UL

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    Senior Member rv9ralph's Avatar
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    Default Re: Model IV-1200 factory tube landing gear alignment discussion

    On my Model 3, I had toe in on the left and neutral on the right. On landing the aircraft wanted to divert to the right so hard the I could hardly keep it straight... it was a struggle.

    To measure I used a straight edge (6 foot level) on the rim of the wheel. To get an accurate line, I used 3/4" nuts as stand-offs from the rims to the straight edge.

    By whatever means, make both neutral.

    The method of correcting by putting a pipe on the axel and tweaking to straighten in not intended to bend the axel, it is intended to twist the landing gear.

    Ralph

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    Default Re: Model IV-1200 factory tube landing gear alignment discussion

    You were also asking about tyre wear with positive camber e.g. top of the tyre further out than bottom. I have the standard grove gear and wheels with 8" Air Trac tyres on my S5 Outback. After a little more than 400 landings, almost all of those on tarmac, there is very little tread on the outside of the tyres and plenty remaining on the inside. This weekend I will swap the tyres around and start wearing the other side.

    Does my experience match others with this set-up?

  6. #6
    Senior Member GWright6970's Avatar
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    Default Re: Model IV-1200 factory tube landing gear alignment discussion

    Ralph,
    What method did you use to correct your alignment?

    Excellent information, thank you!
    Grover Wright
    Flying a KF IV-1200
    ROTAX 912UL

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    Senior Member Slyfox's Avatar
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    Default Re: Model IV-1200 factory tube landing gear alignment discussion

    Quote Originally Posted by rv9ralph View Post
    On my Model 3, I had toe in on the left and neutral on the right. On landing the aircraft wanted to divert to the right so hard the I could hardly keep it straight... it was a struggle.

    To measure I used a straight edge (6 foot level) on the rim of the wheel. To get an accurate line, I used 3/4" nuts as stand-offs from the rims to the straight edge.

    By whatever means, make both neutral.

    The method of correcting by putting a pipe on the axel and tweaking to straighten in not intended to bend the axel, it is intended to twist the landing gear.

    Ralph
    but if you have the grove gear, I think you can get shims from kitfox to kick the wheel in or out.
    steve
    slyfox
    model IV 1200-flying
    912uls
    IVO medium in-flight
    RV7A-flying
    IO-360
    constant speed prop

  8. #8
    Senior Member GWright6970's Avatar
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    Default Re: Model IV-1200 factory tube landing gear alignment discussion

    Auster,
    Good idea on rotating your tires to compensate for wear. Have you ever measured for toe in or out?

    Thank you for relating your experience!
    Grover Wright
    Flying a KF IV-1200
    ROTAX 912UL

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    Senior Member rv9ralph's Avatar
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    Default Re: Model IV-1200 factory tube landing gear alignment discussion

    Ralph,
    What method did you use to correct your alignment?
    Well, that goes to two things. First, I corrected my gear to remove the toe in. It was not difficult due to non-standard gear. There was a horizontal plate that attached the axel to the gear structure that allowed adjustment.

    The final correction was that I replaced the stock with Grove gear, then checked the alignment and used the grove shims to achieve proper alignment.


    Ralph

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    Senior Member PapuaPilot's Avatar
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    Default Re: Model IV-1200 factory tube landing gear alignment discussion

    You always want to check the toe in in relation to the wheel hubs like Ralph said, don't check it at the tires.

    Tires typically wear on the outboard side and rotating them is a normal procedure to maximize the wear and life of a tire. The outside wears because the is the part that touches on the landing as the wheels spin up. As the plane gets heavier the landing gear spreads out and the wheels go from a positive camber to approximately zero. The picture is for cars but it give you an idea of what camber is.

    camber.gif
    Phil Nelson
    A&P-IA, Maintenance Instructor
    KF 5 Outback, Cont. IO-240
    Flying since 2016

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