Page 1 of 2 12 LastLast
Results 1 to 10 of 14

Thread: Rod ends Selecting alternatives to unobtainable/unaffordable originals

  1. #1

    Join Date
    Nov 2011
    Location
    U.K.
    Posts
    41

    Post Rod ends Selecting alternatives to unobtainable/unaffordable originals

    The drawings for my Boredom Fighter project call for Fafnir RE 43 10 double row ball bearing rod ends at the forward, bell crank end of the two aileron push rods. These bearings have a 1/4" bolt hole and are hollow shafted, to fit over the 1/2"OD x 0.35" wall steel pushrod. These are no longer available via A/Spruce and were quite pricey, several years ago. The MS equivalent seems to be MS21152-3 and the only ones I can find on the web are in the region of $350+ each. Way over my budget.
    At the other end of the push rod, "F45-19" rod ends are used and these still seem to be available via Aircraft Spruce, although they were also expensive when I last looked. These have a 1/4" bolt hole and 5/16" internal threads.

    I guess the double row ball bearing type will always be pricey, but maybe they are over specified for what is needed? I want to retain as smooth a feel as reasonably possible for the ailerons but without sacrificing too much and without gaining any weight, at a price I can afford. Any alternative would have to be acceptable to the U.K. L.A.A. engineering dept. and it would be up to me to convince them. They may require a formal modification application, if less than convinced.

    The aircraft is non aerobatic in the U.K. and the VNE is around 115mph, AUW about 750lbs.

    Can anyone suggest where I may be able to find alternative parts and some advice on how to approach this?

    Thanks!

    Ian

  2. #2

    Join Date
    Jul 2014
    Posts
    7
    Quote Originally Posted by IanLaw View Post
    Any alternative would have to be acceptable to the U.K. L.A.A. engineering dept. and it would be up to me to convince them. They may require a formal modification application, if less than convinced.

    Ian
    Would the LAA really know if you substituted the fancy rod ends for standard Heim units? I don't see how they would. If you agree, then get to searching- https://www.mcmaster.com/Rod-Ends

  3. #3

    Join Date
    Aug 2011
    Location
    FA40
    Posts
    757
    "While Fafnir earned a reputation over the years as a high-quality manufacturer of precision ball bearing products, nowadays, engineers and designers find it easy to interchange Fafnir model numbers with a wide range of other high-quality, yet less expensive, alternatives. Contact us to find out which high-quality alternatives products interchange with Fafnir ball bearings."

    https://www.astbearings.com/fafnir-ball-bearings.html

  4. #4

    Join Date
    Jul 2011
    Location
    Clarklake, MI
    Posts
    2,437
    The drawings for my Boredom Fighter project call for Fafnir RE 43 10 double row ball bearing rod ends
    That's a very specific part description. Unless you think you can pull a fast one on the governing authority, may have to fess up and say you did a part substitution. Just curious, what would the penalty if you did a part substitution, didn't tell anyone but later got caught?

  5. #5
    cluttonfred's Avatar
    Join Date
    Oct 2011
    Location
    World traveler
    Posts
    450
    Here are some sources that may turn out cheaper: https://www.controller.com/parts/air...tNum=MS21152-3
    *******
    Matthew Long, Editor
    cluttonfred.info
    A site for builders, owners and fans of Eric Clutton's FRED
    and other safe, simple, affordable homebuilt aircraft

  6. #6

    Join Date
    Nov 2011
    Location
    U.K.
    Posts
    41
    Thanks everyone for the great suggestions and I'll look into them all. I also have to convince my local "LAA" Inspector, as well as the LAA itself, so have to tread a bit carefully.

    I flew our group Aeronca Chief today and the aileron rod ends, at least at the aileron end, are very weedy looking things, with a 3/16" bolt. That aircraft is twice the weight of the Boredom Fighter. The next door Vagabond in our hangar seems to have a cable exiting from the back of the wing, with a thimble and nicopress sleeve to the arm on the aileron.

    Happy New Year to all.

    Ian

  7. #7
    DaleB's Avatar
    Join Date
    Sep 2015
    Location
    KMLE
    Posts
    576
    Sometimes -- I'm not saying this is the case with the current example, but sometimes -- parts get included on plans and in a BOM not because that exact item is required, but because that's what the original designer/builder used. Maybe he had some on hand from another project or a past job, or they were commonly available as cheap surplus at that time, or whatever. Tough to imagine the Boredom Fighter would actually require super high spec rod ends, isn't it?
    Measure twice, cut once...
    scratch head, shrug, shim to fit.

    Flying an RV-12. Building a Fisher Celebrity.

  8. #8

    Join Date
    Jul 2011
    Location
    Clarklake, MI
    Posts
    2,437
    Or, because Don Wolf was an engineer perhaps it was normal for him to spec a part down to the dash number. That's one of the things that impressed me with the Boredom Fighter, it's a well designed airplane!

  9. #9

    Join Date
    Nov 2011
    Location
    U.K.
    Posts
    41
    Thanks Dale & Marty. I'm sure you're both right and I suspect the parts may well have been Grumman surplus. Don was a great guy and always patient and helpful when I started my project many years ago. I asked his advice on what now seem very stupid questions, but he always welcomed my inquiries and replied at length, by hand written letter.

    Ian

  10. #10

    Join Date
    Jul 2017
    Location
    Douglas Flat, CA
    Posts
    53
    Quote Originally Posted by IanLaw View Post
    ...I suspect the parts may well have been Grumman surplus...
    I've seen this exact thing in the Dick Schreder HP-series kit gliders that I support in addition to the HP-24. Dick evidently picked up a thousand or so Fafnir RE3M6-2N two-row ball bearing rod ends after the war, and designed them into the control systems of all the HPs in places where 1/4" spherical rod ends would probably be perfectly adequate.

    --Bob K.
    Bob Kuykendall
    HP-24 kit sailplane project

    HP-24 Project Facebook Page
    http://www.hpaircraft.com/hp-24
    EAA Technical Counselor

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •