Results 1 to 20 of 20

Thread: Gil Pierce & Wup Winn on Tailwheel Shimmy

  1. #1
    Anne's Avatar
    Join Date
    May 2002
    Location
    SE Michigan
    Posts
    1,685
    Post Thanks / Like

    Gil Pierce & Wup Winn on Tailwheel Shimmy

    In the Hands On column in Sport Aviation, Jan 2014, Gil Pierce ("whose son operates Pierce Aero in Graham, Texas") and Wup Winn ("of Alaskan Bushwheel") discuss tailwheel shimmy. It's a very good, informative article on what causes shimmy and how to mitigate it. Thanks, Gil & Wup!

    Anne.
    Baloney is still baloney, no matter how thin you slice it.

  2. #2

    Join Date
    May 2004
    Location
    WOODLAND, CA
    Posts
    319
    Post Thanks / Like
    Went to a Pawnee tailspring and eliminated all shimmy.

  3. #3
    Steve Pierce's Avatar
    Join Date
    Mar 2002
    Location
    Graham, TX
    Posts
    20,542
    Post Thanks / Like
    Bud Davidson did a great job as usual writing that article. Some of the comments written in responce to the article by EAA members are very interesting. http://www.eaa.org/news/2014/release...my-letters.pdf Having used this technique to solve shimmy on everything from Cubs, Citabrias, Huskys, Super Cub, Maules etc. I don't really care what others theories are. It works and that is what matters to me. Because of this article my Dad wrote is posted on my website I get emails from people who want to argue with me about it. I just tell them their theory is interesting but this works.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  4. #4
    AntiCub's Avatar
    Join Date
    Aug 2007
    Location
    North Pole
    Posts
    476
    Post Thanks / Like
    It was all clear till I started reading those comments. I think I'll stick with the original article and the one on Steve's page.

    Phil

  5. #5
    Bearhawk Builder's Avatar
    Join Date
    Aug 2012
    Location
    In the woods
    Posts
    791
    Post Thanks / Like
    I used this method by rearching the spring, no more shimmy - Nuf said.

  6. #6
    Darrel Starr's Avatar
    Join Date
    Jan 2003
    Location
    Plymouth, MN
    Posts
    2,524
    Post Thanks / Like
    Gilbert's Method works -- we have re-arched springs now on two planes with great results. The 1970 graduate from Purdue is all wet but I'm sure no one would ever convince him.

  7. #7
    Gordon Misch's Avatar
    Join Date
    Dec 2003
    Location
    Toledo, Wa (KTDO)
    Posts
    3,796
    Post Thanks / Like
    The 1970 graduate from Purdue is all wet but I'm sure no one would ever convince him.
    He sure is! I
    think there's a lot more going on with that shimmy effect than any of the posters alluded to. It's just like flutter, with a myriad of factors influencing the dynamics.
    Gordon

    N4328M KTDO
    My SPOT: tinyurl.com/N4328M (case sensitive)

  8. #8
    SJ's Avatar
    Join Date
    Jan 2002
    Location
    Kansas City, USA
    Posts
    15,318
    Post Thanks / Like
    Gil & Wup are the shimmy kings. This has been a problem they were dealing with since the roaring 20's.

    "Often Mistaken, but Never in Doubt"
    ------------------------------------------

  9. #9

    Join Date
    Dec 2006
    Location
    Meanwhile,...
    Posts
    5,371
    Post Thanks / Like
    SJ, excellent work on the visual now all we need is a song...
    Last edited by OLDCROWE; 03-07-2014 at 08:28 AM.
    Remember, These are the Good old Days!

  10. #10
    AntiCub's Avatar
    Join Date
    Aug 2007
    Location
    North Pole
    Posts
    476
    Post Thanks / Like
    Quote Originally Posted by Gordon Misch View Post
    He sure is! I
    think there's a lot more going on with that shimmy effect than any of the posters alluded to. It's just like flutter, with a myriad of factors influencing the dynamics.
    My thought exactly. I suspect in a shimmy there's a resonant oscillation going on, very similar to control flutter.

  11. #11
    Cub Builder's Avatar
    Join Date
    Mar 2011
    Location
    North Central AR
    Posts
    686
    Post Thanks / Like
    Very simple practical test to prove out the theories, which we did a few years ago at one of our EAA meetings. Large R/C tailwheel assembly including spring and a table top belt sander to simulate rolling it across the ground. Tilt the spring up and down with some loading on the spring to see what happens. The results are as outlined in the article.

    -CubBuilder

    Click image for larger version. 

Name:	TW Shimmy.jpg 
Views:	129 
Size:	25.4 KB 
ID:	15184
    Tailwheel shimmy simulator.

  12. #12
    scott c's Avatar
    Join Date
    Mar 2011
    Location
    North Battleford SK
    Posts
    59
    Post Thanks / Like
    Can someone offer help with method of rearching 1-1/4 pa18 tailspring? Link above does not seem to be working.

  13. #13
    Steve Pierce's Avatar
    Join Date
    Mar 2002
    Location
    Graham, TX
    Posts
    20,542
    Post Thanks / Like
    The link did not tell how to rearch. Take the spring to spring shop and have them rearch it cold. More info here. http://www.pierceaero.net/tws.php
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  14. #14
    scott c's Avatar
    Join Date
    Mar 2011
    Location
    North Battleford SK
    Posts
    59
    Post Thanks / Like
    Quote Originally Posted by Steve Pierce View Post
    The link did not tell how to rearch. Take the spring to spring shop and have them rearch it cold. More info here. http://www.pierceaero.net/tws.php

    Thank you Steve

  15. #15
    Darrel Starr's Avatar
    Join Date
    Jan 2003
    Location
    Plymouth, MN
    Posts
    2,524
    Post Thanks / Like

  16. #16

    Join Date
    Jan 2007
    Posts
    2,285
    Post Thanks / Like
    I rearch mine with press and 6 inch pipe. Do bottom first and arch others to match. One thing I really notice on my 3 spring is how much easy it is to steer when it is properly arched.
    DENNY

  17. #17
    SchulerJL's Avatar
    Join Date
    Aug 2009
    Location
    Peoria, Illinois
    Posts
    584
    Post Thanks / Like
    Quote Originally Posted by Scruffdog View Post
    Went to a Pawnee tailspring and eliminated all shimmy.
    I have to put my 2 cents in:

    http://youtu.be/JiYFdaVKR5k


    Thank you Alaskan Bushwheel for everything you have done to make flying my plane very fun!!

  18. #18

    Join Date
    Sep 2006
    Location
    corvallis,or
    Posts
    422
    Post Thanks / Like
    So I checked today and the head of my bolt is aft of vertical like it's supposed to be and I still get shimmy. What next?

    its a Alaska bush wheels spring with 85 hours on it. One year old.

  19. #19
    Crash, Jr.'s Avatar
    Join Date
    May 2015
    Location
    Anchorage, AK
    Posts
    409
    Post Thanks / Like
    Vertical is good but tilted back (positive castor) is even better. When the spring is compressed like when you are loaded heavy or when the spring flexes as the tail touches down the bolt will tilt forward of vertical and you will get shimmy. Also condition of the thrust washer stack, number of shimmy dampening springs, and steering chain setup have a lot to do with it.

  20. #20
    Darrel Starr's Avatar
    Join Date
    Jan 2003
    Location
    Plymouth, MN
    Posts
    2,524
    Post Thanks / Like
    Piper J5.5: did you check it fully loaded to gross weight? And perhaps a g load as the tail wheel goes on firmly?

Similar Threads

  1. Tailwheel Shimmy
    By SJ in forum Super Cub Sick Bay
    Replies: 72
    Last Post: 04-15-2017, 06:43 AM

Bookmarks

Bookmarks

Posting Permissions

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