Page 2 of 2 FirstFirst 12
Results 41 to 63 of 63

Thread: HELP! Bent J4A Cub Coupe Front Spar Lift Strut Fittings

  1. #41

    Join Date
    Aug 2021
    Posts
    17
    Post Thanks / Like
    Here's a pic of my spar/strut brackets.

    The spacing of the bolt holes is quite different to the drawings on the PA18 (super cub project website)
    Click image for larger version. 

Name:	PXL_20210913_134205103.jpg 
Views:	42 
Size:	168.1 KB 
ID:	57528

  2. #42
    cubdriver2's Avatar
    Join Date
    Apr 2003
    Location
    upstate NY
    Posts
    10,832
    Post Thanks / Like
    Join the J3 site, lots of wooden spar guys over there

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"

  3. #43
    skywagon8a's Avatar
    Join Date
    Mar 2008
    Location
    SE Mass
    Posts
    11,434
    Post Thanks / Like
    Quote Originally Posted by J4A View Post
    Here's a pic of my spar/strut brackets.

    The spacing of the bolt holes is quite different to the drawings on the PA18 (super cub project website)
    Click image for larger version. 

Name:	PXL_20210913_134205103.jpg 
Views:	42 
Size:	168.1 KB 
ID:	57528
    If I were you, I would use the drawings from Buggs' website as reference material and your bent fittings for hole spacing dimensions. While I realize you are in the UK, I would make the parts as close as possible to the originals with minimal communication with the authorities. This is assuming you can not find a drawing which is specifically calling out the applicability for the J-4.
    N1PA

  4. #44

    Join Date
    Mar 2016
    Location
    Down low in the hills of Vermont USA
    Posts
    1,801
    Post Thanks / Like
    In the past I had reverse engineered parts that were un-obtainable and no drawings available.
    Regards, Charlie
    Super Coupe E-AB build in process

  5. #45
    Marty57's Avatar
    Join Date
    Jan 2005
    Location
    Nipomo, Ca
    Posts
    1,465
    Post Thanks / Like
    What am I missing here .... isn't this the same part? Listing says it fits the J3, different measurements of holes maybe?

    Marty57

    Click image for larger version. 

Name:	lift strut fitting.jpg 
Views:	36 
Size:	178.0 KB 
ID:	57530
    N367PS
    Psalm 36:7 "High and low among men find refuge in the shadow of His wing"
    www.marty2plus2.com
    Likes BC12D-4-85 liked this post

  6. #46
    skywagon8a's Avatar
    Join Date
    Mar 2008
    Location
    SE Mass
    Posts
    11,434
    Post Thanks / Like
    Quote Originally Posted by Marty57 View Post
    What am I missing here .... isn't this the same part? Listing says it fits the J3, different measurements of holes maybe?

    Marty57

    Click image for larger version. 

Name:	lift strut fitting.jpg 
Views:	36 
Size:	178.0 KB 
ID:	57530
    He has a J-4 not a J-3.
    N1PA

  7. #47
    BC12D-4-85's Avatar
    Join Date
    Feb 2016
    Location
    Fairbanks, AK.
    Posts
    3,024
    Post Thanks / Like
    Has J4A made a tracing with dimensions off the damaged parts? May have missed that step.

    Gary

  8. #48

    Join Date
    Jan 2016
    Posts
    54
    Post Thanks / Like
    Quote Originally Posted by BC12D-4-85 View Post
    Has J4A made a tracing with dimensions off the damaged parts? May have missed that step.

    Gary
    not yet, the easiest step right now would be for him to post the dimensions, and hole distances of his.

    Someone here I’m sure has a J-3 and a J-5 they could get measurements off of.

    Ten bucks says it’s the same one that a J-5 wood wing uses.

  9. #49
    Marty57's Avatar
    Join Date
    Jan 2005
    Location
    Nipomo, Ca
    Posts
    1,465
    Post Thanks / Like
    Quote Originally Posted by skywagon8a View Post
    He has a J-4 not a J-3.
    I'm aware of that but look at the pictures; same number of holes and placement looks the same. Something to check out. Piper sure liked to interchange parts.
    Marty57
    N367PS
    Psalm 36:7 "High and low among men find refuge in the shadow of His wing"
    www.marty2plus2.com

  10. #50

    Join Date
    Aug 2021
    Posts
    17
    Post Thanks / Like
    Take a look at the hole sizes, the N strut is held on by a threaded piece of wire just above the strut. I'm not sure I've seen other fittings with that style off attachment.

  11. #51
    supercrow's Avatar
    Join Date
    Dec 2008
    Location
    Smith Pond near Millinocket, Me
    Posts
    533
    Post Thanks / Like
    Quote Originally Posted by J4A View Post
    Take a look at the hole sizes, the N strut is held on by a threaded piece of wire just above the strut. I'm not sure I've seen other fittings with that style off attachment.
    J-3 uses that threaded rod inside a tube and has no N strut.

  12. #52
    supercrow's Avatar
    Join Date
    Dec 2008
    Location
    Smith Pond near Millinocket, Me
    Posts
    533
    Post Thanks / Like
    At least that is the case in the early wood spar J-3 wings.

  13. #53

    Join Date
    Sep 2003
    Posts
    7,596
    Post Thanks / Like
    The wood spar fittings sure look easy to duplicate. Not sure of the alloy, but I would guess 1025. A good structural engineer might suggest 4130 - might pay to ask a few questions. There is a seriously knowledgable lady on the J3 forum who has made every single piece of a J3 from scratch - bet she could help.

    On the J3 there is a weld on the forward pair where the lift strut attaches. Looks really easy to do, but I would have it done by a pro. The rest is just cutting, drilling, and folding. A big brake will help a lot.
    Thanks mixer, RVBottomly thanked for this post

  14. #54
    Marty57's Avatar
    Join Date
    Jan 2005
    Location
    Nipomo, Ca
    Posts
    1,465
    Post Thanks / Like
    Quote Originally Posted by J4A View Post
    Take a look at the hole sizes, the N strut is held on by a threaded piece of wire just above the strut. I'm not sure I've seen other fittings with that style off attachment.
    That's the same as on my 2+2 wing; the threaded rod goes through the N strut. I think the part I used was a PMA's part but no longer available from Wag. From the first picture in this post, you can see the same wire through the bent lift strut; you can see the nut and jam nut securing it in place. If all the holes and dimensions are the same, other than that hole for the threaded rod, why not weld a washer on the outside of that hole that is the correct size for the threaded rod? Guess that would be a question for the IA returning it to service after the repair.

    Marty57
    N367PS
    Psalm 36:7 "High and low among men find refuge in the shadow of His wing"
    www.marty2plus2.com

  15. #55

    Join Date
    Aug 2021
    Posts
    17
    Post Thanks / Like
    Click image for larger version. 

Name:	strut measurements.jpg 
Views:	48 
Size:	84.3 KB 
ID:	57542
    I took some rough measurements with a ruler to the nearest 16th. Does anybody have a J5 drawing to compare this to?
    Attached Files Attached Files

  16. #56
    skywagon8a's Avatar
    Join Date
    Mar 2008
    Location
    SE Mass
    Posts
    11,434
    Post Thanks / Like
    Quote Originally Posted by bob turner View Post
    The wood spar fittings sure look easy to duplicate. Not sure of the alloy, but I would guess 1025. A good structural engineer might suggest 4130 - might pay to ask a few questions. There is a seriously knowledgable lady on the J3 forum who has made every single piece of a J3 from scratch - bet she could help.

    On the J3 there is a weld on the forward pair where the lift strut attaches. Looks really easy to do, but I would have it done by a pro. The rest is just cutting, drilling, and folding. A big brake will help a lot.
    On the J-3 .062" 1025 steel.
    http://www.supercubproject.com/drawi...s/A3290623.pdf
    N1PA
    Likes jrussl liked this post

  17. #57

    Join Date
    Aug 2021
    Posts
    17
    Post Thanks / Like
    Quote Originally Posted by skywagon8a View Post
    Is there a good reason why you wouldn't/couldn't use 4130 instead?

  18. #58
    skywagon8a's Avatar
    Join Date
    Mar 2008
    Location
    SE Mass
    Posts
    11,434
    Post Thanks / Like
    Quote Originally Posted by J4A View Post
    Is there a good reason why you wouldn't/couldn't use 4130 instead?
    No reason at all. Just be more careful in the bend radius when you make the bends. There are charts available for this purpose.
    This is some discussion on the matter. https://www.aircraftspruce.com/catal.../metalinfo.php

    Drawing 14172 calls for a 1/16" (.0625") radius of bend or one times the thickness of the 1025 materiel. According to the Aircraft Spruce information, they call for 3 times the thickness for the bend radius for 4130. If you follow those bend radius recommendations you should be safe. Be aware there is less likely to be cracks formed in the bend when the bend is across the grain. This is preferred when possible.
    N1PA

  19. #59

    Join Date
    Mar 2016
    Location
    Down low in the hills of Vermont USA
    Posts
    1,801
    Post Thanks / Like
    Could you measure the width of the channel, I do not have my J4 here. I think you will find a length of square tube will do what you need without fighting to get shop bends that do not crack along the edges or need to worry about post processing heat treat.
    Regards, Charlie
    Super Coupe E-AB build in process
    Likes BC12D-4-85 liked this post

  20. #60
    RVBottomly's Avatar
    Join Date
    Sep 2017
    Location
    Asotin County Washington (KLWS)
    Posts
    1,229
    Post Thanks / Like
    Quote Originally Posted by J4A View Post
    Click image for larger version. 

Name:	strut measurements.jpg 
Views:	48 
Size:	84.3 KB 
ID:	57542
    I took some rough measurements with a ruler to the nearest 16th. Does anybody have a J5 drawing to compare this to?
    What is the width of the part, outside dimensions at the flanges?

  21. #61

    Join Date
    Aug 2021
    Posts
    17
    Post Thanks / Like
    It's 1" across the flanges

  22. #62
    skywagon8a's Avatar
    Join Date
    Mar 2008
    Location
    SE Mass
    Posts
    11,434
    Post Thanks / Like
    N1PA

  23. #63

    Join Date
    Mar 2016
    Location
    Down low in the hills of Vermont USA
    Posts
    1,801
    Post Thanks / Like
    And 1" X .065 is readily available most everywhere if shipping from over here is preventive.
    There are options to go up to 1.25 wide as well for more bending resistance which might not be needed with added bracing as previously mentioned here.

    Thicker wall tube probably needs to be in mild steel which even being a welded tube in 1018 alloy is strong. The welded tube you would cut your slit along the weld.
    Regards, Charlie
    Super Coupe E-AB build in process

Similar Threads

  1. Lift strut spar attach fittings
    By N75LH in forum Super Cub Sick Bay
    Replies: 8
    Last Post: 09-28-2012, 10:04 PM
  2. Slop in front lift strut - fuselage fitting
    By JimC in forum Super Cub Sick Bay
    Replies: 3
    Last Post: 02-27-2007, 02:53 PM
  3. Lift Strut Attatch Fittings
    By j3jm in forum Cafe Supercub
    Replies: 10
    Last Post: 11-24-2003, 10:58 PM

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
  •