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Thread: Building a Scratch Built Cub

  1. #41
    stknrddr's Avatar
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    Project Update - Stabilizer Attachment to the Fuselage

    I'd like to share progress made attaching the stabilizer assembly to the fuselage.
    I built the stabilizer and elevators a while ago, so I'll begin with a quick review.

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    A photo of the scratch built assemblies.
    Balanced elevators.

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    We used some original parts to create the templates (fixtures) to make the stabilizers and elevators.
    Joe Norris (on this list) loaned us some parts. You'll notice the stabilizer in the photo is not balanced,
    so I simply made the stabilizer fixture to accommodate a balance elevator.

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    A photo of the stabilizer leading edge tube in the fixture.

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    Bending the heavy tube required making a bending fixture as shown.
    I inserted a coil spring into the tube, and using the cupped fixture, the tube bent nicely without kinking.
    Don't forget to remove the internal spring if you elect o do this.

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    A photo of Charlie welding up an elevator.


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    This is a length of hinge stock. We'll cut pieces off, and cut down the centerline to create
    hinges that kind of cup onto the elevator or stabilizer tubes.

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    When pieces of hinge stock are cut to length, they can be tack welded in place as shown.
    The cupped piece acts as an appropriate spacer for fabric and paint allowances.
    After final welding, oiliite bushings will be pressed in to obtain the final bushing diameter for 1/4" diameter pins.

    Click image for larger version. 

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    The entire stabilizer and elevator assembly then gets placed onto the fuselage.
    I clamped tubing vertically to the stabilizer, from the floor up, to balance and "stabilize" the assembly
    where it needs to be located. This took a lot of time.

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    These brackets (saddles) need to be positioned carefully in place and tack welded.

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    I made and used this gage block to properly locate the stabilizer
    from the tail post prior to welding.

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    Using clamps and blocks to position the tail assembly just right.

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    Blocks and clamp on the front end. You'll notice that I am not using a jack screw. I'll use a trim tab on
    an elevator as I've seen others use. Again, I'm building a light sport plane (I think).

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    By the way, I used a set of trammel points to square up the stabilizer assembly
    to the fuselage. I located a center point on the fuselage about 4 or 5 feet ahead of the tail section,
    and trammed the tail feathers equal distance on both the left and right stabilizers.

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    I used a transfer punch first to locate the hole location in the fuselage tube.
    I then drilled a pilot hole, and ran a locating pin to ensure everything was aligned well,
    than I drilled the final hole diameter and added a bushing to the lower tube.
    Long bolts will eventually hold this assembly together.

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    This photo shows the stabilizer and elevators in place, with the vertical stabilizer and the rudder
    clamped in place. It turned out well.

    Thanks for looking.

    John
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  2. #42
    tedwaltman1's Avatar
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    Amazing. Very inspirational. Thank you for the pictures and detail explanations.

  3. #43
    WanaBNACub's Avatar
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    This is such an awesome project! Keep the pics coming, your an inspiration for my next build!

  4. #44
    stknrddr's Avatar
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    Lunch Time Aviation - Project Update

    It's lunch time which means a chance to post an update. Baggage Compartment Floor

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    My baggage compartment is basically to the plans, where
    I sheared and bent steel sheet for the rails, and positioned
    them onto the fuselage as shown using spring clamps.

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    The plans call for 0.032" thick mild steel (1025) sheet metal, while I used
    0.032" 4130 steel sheet. I dimensioned the pieces per plans, however I
    added a little return bend along the bottom edge to add a little
    more stiffness to the part. It's the little 1/8" or so bend I added
    as seen in the photo.

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    Here's a photo of the pieces welded in place.
    This is the area directly behind the rear seat.

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    This is better photo of how we welded up the parts.
    Charlie did a nice job welding the pieces.
    I used flange nuts riveted in place which will be used
    to hold the plywood, or composite floor sheet in place.

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    A photo of the underside of the floor rail with the
    flange nut riveted in place.

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    Here you see the rivets are countersunk onto the steel for a flat finish.
    Also shown here is how we welded the rail to the cross member
    for the rear seat. This is also a good photo of the additional bend
    along the bottom edge of the rail.

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    This is a rivet squeezer used to crimp the rivets. The distance between
    the jaws is adjustable to get the correct squeeze for a given rivet size.
    Also shown, is the counter sinking tool, to countersink the sheet metal.

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    A photo of a piece of scrap plywood in place just to see what it looks like.
    I have not decided what to do for the back of the baggage compartment.
    Maybe I'll install tabs to attach a similar plywood sheet, or install
    a canvas style back; or the lower half of the back may be plywood,
    while the upper half is canvas?
    Any thoughts and photos of options are appreciated.

    Thank you,
    John
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  5. #45

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    Good work!!

  6. #46
    stknrddr's Avatar
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    Builders Update - Scratch built Ribs Finished

    I finished building my ribs. Here are a couple of photos.
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    It took me a long time to decide which style of rib to build. I made samples of different
    style ribs to learn which ribs were suitable for me to build. Due to the
    fact that I could make this style of rib with minimal shop tools,
    and at home, I decided on the single cap strip with intercostals. I basically
    fabricated and assembled all the parts using bulk materials.
    I also now have a new set of wing spars from Jay at Javron Inc. to keep my building.

    I will follow up with another post on the fabrication of these ribs in the near future.
    Thanks for looking,
    John
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  7. #47
    tedwaltman1's Avatar
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    Those ribs look GREAT! How did you get the leading edge curve so nice (and consistent)?
    Thanks stknrddr thanked for this post

  8. #48
    jnorris's Avatar
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    Looks great John. Keep up the good work!!
    Joe

    Fortis Fortuna Adiuvat
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  9. #49

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    Quote Originally Posted by stknrddr View Post
    Builders Update - Scratch built Ribs Finished

    I finished building my ribs. Here are a couple of photos.
    Click image for larger version. 

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    It took me a long time to decide which style of rib to build. I made samples of different
    style ribs to learn which ribs were suitable for me to build. Due to the
    fact that I could make this style of rib with minimal shop tools,
    and at home, I decided on the single cap strip with intercostals. I basically
    fabricated and assembled all the parts using bulk materials.
    I also now have a new set of wing spars from Jay at Javron Inc. to keep my building.

    I will follow up with another post on the fabrication of these ribs in the near future.
    Thanks for looking,
    John
    Hi,Stknrddr,I am a cub homebuilter in China,I want to know what is single cap strip?Could you show this material bya clearer picture?and tell me composition of aluminium alloy,2024-T3 or 6061T651?
    Likes mike mcs repair liked this post

  10. #50
    stknrddr's Avatar
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    To answer a couple of recent questions, I have the following to offer:

    1. Cap Strip Material used- I used cap strip material from Carlson Aircraft. According to their web site,
    the material is 6061-T6 aluminum. They provide both a "T" shape and an "L" shape, and I elected to use the "L" shape.
    They're web address is carlsonaircraft dot com.
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    2. To create a consistent bend at the leading edge - I used a metal shrinker to bend the capstrip slightly into a curve.
    Place the cap strip into the jaws and squeeze, move the material accordingly, and shrink...
    I fabricated and used a continuous shape form to set the cap strip in to ensure the perimeter of the cap strip matched
    the entire profile of the form. Due to the stiffness of the cap strip material, the shrinker is needed to bend the material,
    as I found it to be very difficult to create a nice bend any other way.
    Mary at Carlson Aircraft advised me to use a shrinker, and I listened to her.
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    I will follow up with additional posts on the entire rib building process.
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    Thank you for looking.
    john
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  11. #51
    tedwaltman1's Avatar
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    Again, sincere congratulations for simply AWESOME fabrication work!
    Thanks stknrddr thanked for this post
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  12. #52
    Marty57's Avatar
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    The ribs are looking great! I recognize those basement pictures a few posts back ...... great work.
    Marty
    N367PS
    Psalm 36:7 "High and low among men find refuge in the shadow of His wing"
    www.marty2plus2.com
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  13. #53
    stknrddr's Avatar
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    Project Update - Fabricating my Scratch Built Ribs
    Step-By-Step Rib Building Process.

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    Here's a photo of the final ribs.

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    Recall, that I am working with a building partner who is also scratch building
    a cub. I made a set of forms (template and die set) to experiment making a
    three piece hydro-formed rib which we pressed using a hydraulic press.
    Although the rib turned out very nice, I elected to build ribs using the single
    piece cap strip, and aluminum intercoastals (truss style), as I could more
    easily make these in my home shop with basic tools, and I liked the
    single piece rib.

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    The photo above shows our three piece stamped rib,
    my trussed rib, and an original Cub rib.

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    I drew the traditional USA35B cub rib profile, printed, and glued the print
    onto a smooth board (shelf board). I built both left (shown here) and right
    hand rib fixtures, as I am using the "L" shape cap strip material, so I wanted
    symmetry on each wing regarding the direction of the "L" in the ribs.

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    I then cut the rib profile from another shelf board and over layed it onto
    the print. I then cut a nailed the little blocks onto the board to locate the
    intercoastals. Here's a photo of the right hand rib form.

    Click image for larger version. 

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    I bought 6061-T6 aluminum cap strip material from Carlson Aircraft (on the web).
    I elected to have Carlson machine the flange off at what would be the nose
    of the rib (they know where to cut it), so the material may be folded as shown for
    mail order delivery.

    Click image for larger version. 

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    I used a metal shrinker to set the bends into the cap strips. Insert the material
    and squeeze to "set" the bend; keep moving along to bend where needed.
    Inexpensive shrinkers can be bought for non-industrial use.

    Click image for larger version. 

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    Make sure the final rib fits nicely into the form. Cut the trailing
    end of the cap strips to final length. I over lapped the ends and
    married them together for a clean and tight fit.

    Click image for larger version. 

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    Fabricating Intercoastals - I then sheared a bunch of aluminum to
    width, and cut pieces to the approximate required length. I then pressed
    a bead down the center of the part using a small arbor press. A friend of mine
    milled a slot into a piece of flat steel stock, and welded a piece of round
    stock onto a second piece of flat stock to fabricate a bead former. I
    did not have easy access to a roller style bead former, and this worked
    very well in my home shop.

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    I then bent flanges on the intercoastals as shown using a small bench top break.

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    Cut and sand parts to final shape. Place as shown into the fixture,
    mark and pre-drill the holes, then drill the final hole size, and add clecos as
    you go to hold everything in place.

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    Ensure the cap strip is always tight against the form when inserting
    the intercoastals, and make sure the intercoastals are tight against
    their form blocks to maintain consistency. Use clamps when needed.

    Click image for larger version. 

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    Pop the rib out of the form, take the whole thing apart to de-burr all
    of the holes. Place it all back into the form for pre-assembly, again
    using clecos prior to riveting.

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    Pop the rib out of the form again, and replace a cleco with a rivet, and
    continue. You will notice that I drilled some holes in the wood form where
    the clecos extend into the form. This is done to allow the rib to set
    flat in the form when the clecos are in place. I used solid aluminum rivets
    and a rivet squeezer.

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    I fabricated all of the full length ribs first, then modified the form
    slightly to make the shorter ribs as shown.

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    Before I went too far, I wanted to make sure that the short ribs
    were matching up well enough, so I made a short sample of a
    false spar and placed it as shown. I was very happy to see
    how well everything fit up.

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    The final stacks of ribs. To reduce complexity and weight, and
    having the desire to build light, I will not have flaps, therefore
    I have more full length ribs than a cub with flaps has.

    I learned these processes by scouring the web, looking at kit plane designs,
    and from other builders on Supercub dot org. I hope others can
    benefit from my posts as well.

    Thank you for looking.

    John
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  14. #54

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    Awesome,thank you for sharing!
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  15. #55
    tedwaltman1's Avatar
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    Hats off to you for the exceptional dedication and clearly outstanding craftsmanship!
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  16. #56
    www.SkupTech.com mike mcs repair's Avatar
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    Quote Originally Posted by stknrddr View Post
    To answer a couple of recent questions, I have the following to offer:

    1. Cap Strip Material used- I used cap strip material from Carlson Aircraft. According to their web site,
    the material is 6061-T6 aluminum. They provide both a "T" shape and an "L" shape, and I elected to use the "L" shape.
    They're web address is carlsonaircraft dot com...
    john
    ah, thats probably where the backcountry gets their rib material is from? it's an L shape... but that website is not responding at the moment for me...

  17. #57

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    Quote Originally Posted by mike mcs repair View Post
    ah, thats probably where the backcountry gets their rib material is from? it's an L shape... but that website is not responding at the moment for me...
    I think this type cap strip more suitable,from Dokata

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    Last edited by sageelite; 09-19-2017 at 07:10 PM.
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  18. #58
    stknrddr's Avatar
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    Project Update - Simulated Wings

    Click image for larger version. 

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    I finished the fabrication of these mini-wings which I will use to position the
    "wing attachment fittings" to the fuselage. I want to ensure the center-to-center
    distance of the fittings will be match the actual wings I make, as well as be at
    the correct angle to the fuselage. By mounting the mini-wings to the fuselage,
    I will also be able to install the Piper style channel above the cabin area, to
    ensure the airfoil shape above the cabin area matches the airfoil shape on
    the wings.

    Click image for larger version. 

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    I bought new wings spars from Javron, located in Minnesota. Jay DeRosier
    at Javron delivered the spars to Oshkosh where I picked them up. Jay also
    provided some scrap pieces of spar stock for me to make the mini-wings.
    I fabricated a wood frame of the appropriate size to square up and solidify
    the wing assemblies.

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    I bought threaded studs from a local hardware store. One end of the stud is
    threaded as a wood screw, and the other end is threaded as a machine screw.
    I drilled through the spars, into the wood frame, then threaded in the stud,
    followed by using a wing nut to fasten it.

    Click image for larger version. 

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    I attached the ribs to the spars, and added a piece of leading edge skin.

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    I then fabricated a piece of trailing edge material and attached it.

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    The simulated wings turned out pretty good. Making the wings
    provided me the opportunity to investigate the assembly
    process of a lager wing, and use them to fit the wing attachment
    fittings. Most importantly, I was able to physically test the fit up
    of the ribs to the spars, to ensure everything was built correctly.

    Thank you for looking.

    john
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  19. #59
    www.SkupTech.com mike mcs repair's Avatar
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    Quote Originally Posted by stknrddr View Post
    Project Update - Simulated Wings
    I will also be able to install the Piper style channel above the cabin area, to
    john

    make sure you take into consideration the thickness of a skylight,(and windshield in front) if you are putting one on... most cubs are wrong, as they didn't come with skylights originally, till later... I'm picky...

  20. #60
    stknrddr's Avatar
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    Quote Originally Posted by mike mcs repair View Post
    make sure you take into consideration the thickness of a skylight,(and windshield in front) if you are putting one on... most cubs are wrong, as they didn't come with skylights originally, till later... I'm picky...
    Yes, I understand what you mean. I probably will want to install a skylight, and I'll need to consider how to get everything to line up correctly and neatly up there.
    Thanks for bringing this up.

  21. #61
    RVBottomly's Avatar
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    Quote Originally Posted by stknrddr View Post

    A photo of the stabilizer leading edge tube in the fixture.

    Click image for larger version. 

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    Bending the heavy tube required making a bending fixture as shown.
    I inserted a coil spring into the tube, and using the cupped fixture, the tube bent nicely without kinking.
    Don't forget to remove the internal spring if you elect o do this.
    This is really great. What kind of spring did you use?

    I looked up springs for tube bending but only find 24" coiled springs from Wicks. It looks like your curves are a lot longer than that.

    The springs I saw have flares at the end, presumably so they didn't slip too far inside. Did you cut them off or find something better to use?

  22. #62
    www.SkupTech.com mike mcs repair's Avatar
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    Quote Originally Posted by RVBottomly View Post
    This is really great. What kind of spring did you use?

    I looked up springs for tube bending but only find 24" coiled springs from Wicks. It looks like your curves are a lot longer than that.

    The springs I saw have flares at the end, presumably so they didn't slip too far inside. Did you cut them off or find something better to use?
    filling it with sand and capping ends will probably work also...

    see my video on making breather tubes


  23. #63
    stknrddr's Avatar
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    Quote Originally Posted by RVBottomly View Post
    This is really great. What kind of spring did you use?

    I looked up springs for tube bending but only find 24" coiled springs from Wicks. It looks like your curves are a lot longer than that.

    The springs I saw have flares at the end, presumably so they didn't slip too far inside. Did you cut them off or find something better to use?
    The spring is simply an extension spring with the ends cut off. I happened to get lucky in that I had this spring laying around, and it fit just right, and made a sliding fit into the tube, matching the inside diameter of the tube nicely. I have bought springs for other purposes from McMaster-Carr ( Industrial Supply Company), and the choices are many. A person can buy directly from them using their online catalog. In this case, I pushed the spring well into the tube and made the bends, then kind of shook the spring out. In the event the spring might have gotten stuck, I was sure that I could have pushed the spring out using a flexible hose or something.
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  24. #64

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    Made my breather from siphon tube. You know
    one of them irrigation things.

  25. #65
    stknrddr's Avatar
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    ​Project Update - Turtle Deck

    This is an update of fabricating and placing the turtle deck section on the fuselage.

    Click image for larger version. 

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    I temporarily attached the sample wings I made onto
    the air frame. This was done to properly locate the 3
    turtle deck stringers at the trailing edge of the wings.

    Click image for larger version. 

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    I c-clamped the wing fittings as shown, as I do not want to weld the
    fittings in place until I have the final wings fabricated to ensure
    better alignment of the wings to each other and to the fuselage.

    In the above photo, you will also see a formed wing cap strip setting
    in place. We fabricated our own piper channel using 0.025" thick steel
    sheet, 1" wide. A shear and break were used to bend it into a channel.

    Click image for larger version. 

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    I fabricated a fixture to bend an arc in the piper channel to the shape
    of the airfoil. I routered a square groove into the edge of a radiused
    section of fiber-board, fabricated a steel cap to retain the channel,
    and kind of bent the channel around the radius, moving the channel as needed.

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    I then used the original wing rib fixture to match the airfoil
    shape for the steel cap strip.

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    I fabricated the stringer bulkhead station located in the tail section.
    then ran string lines to the trailing edge of the wings. The string lines
    represent the final located of the stringers.

    Click image for larger version. 

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    The location of the strings and ultimately the stringers is
    important to ensure the fabric lays in-line with the
    cabin windows.

    Click image for larger version. 

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    We needed a way to copy the shape of the future bulk head
    stations, so a friend of ours made this plywood bevel square
    contraption using a laser cutter. Slotted holes and wing
    nuts make it easily adjustable to get the correct shape
    around the strings.

    Click image for larger version. 

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    Transferring the bulkhead shape to a work bench,
    by tracing the interior perimeter, provided a set
    of lines to follow when welding up the bulk head
    stations.

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    Here's one of the bulk heads getting fabricated.

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    Here we have two bulk heads welded in place, with
    the bevel square thing setting in place for the next
    location.

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    I cut and fit the parts, and Charlie does the welding.
    Here he uses a 0.040" tungsten for the thin parts
    instead of his usual 1/16" tungstens.

    Click image for larger version. 

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    This is the last bulk head location. The process
    we used to locate and align the bulk heads worked
    very well for us.

    Thank you for looking. John
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  26. #66
    RVBottomly's Avatar
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    Very nice.

    That plywood bevel square is similar to a plywood gauge I put together for making boat frame patterns. Yours is more elegant, though.

    BTW, I'm taking notes and stealing ideas. Thanks for putting these up.
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  27. #67
    skywagon8a's Avatar
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    Quote Originally Posted by stknrddr View Post
    ​Project Update - Turtle Deck

    I fabricated the stringer bulkhead station located in the tail section.
    then ran string lines to the trailing edge of the wings. The string lines
    represent the final located of the stringers.

    Click image for larger version. 

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    The location of the strings and ultimately the stringers is
    important to ensure the fabric lays in-line with the
    cabin windows.

    Click image for larger version. 

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    Thank you for looking. John
    John, You are doing excellent work. Are you intentionally relocating the center top fuselage stringer to be different than Piper's? The forward end of the top center stringer passes above the rear spar carry through, not as you have it in line with the wing trailing edge.
    Last edited by skywagon8a; 12-14-2017 at 09:27 AM.
    N1PA
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  28. #68
    jnorris's Avatar
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    Excellent work John, as always!
    Joe

    Fortis Fortuna Adiuvat
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  29. #69
    stknrddr's Avatar
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    John, You are doing excellent work. Are you intentionally relocating the center top fuselage stringer to be different than Piper's? The forward end of the top center stringer passes above the rear spar carry through, not as you have it in line with the wing trailing edge.
    Yes, I see what you mean. The center string line is actually above the trailing edge, but a person can't really tell from the photos. I've been on the fence about how tall to make the center peak through this area, as it is flatter than by the plans. If I elect to extend the sky-light farther aft, I do not want to have to put a crease in the lexan (or whatever I use), or at least not a significant crease, and I realize that a crease may help stiffen up the lexan for the better. I noticed on one of the experimental Cubs that I often look at included a little stand off to raise the stringers a little higher than the corners or peaks of the bulk heads, and I thought I could resort to that if I want to raise any of the stringers. My corner stringers are for the most part, headed right toward the trialing edge, however I have left opportunity to flex the stringers upward to fair into the trailing edge as well.
    Thanks for your thoughts as I would hate to get too far down the wrong path.

  30. #70
    skywagon8a's Avatar
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    I have a skylight on mine made from plexiglas. I bought a heat tape which is a little over an inch wide to heat where the crease in the center goes. There are also two reverse creases which goes from the forward center diagonally towards the wing trailing edge. This method works very well though there is a learning curve in using the heat tape.
    N1PA
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  31. #71

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    Golly! Didn,t know a kit can be made. You are a true airplane builder.
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  32. #72
    Gordon Misch's Avatar
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    Quote Originally Posted by skywagon8a View Post
    I have a skylight on mine made from plexiglas. I bought a heat tape which is a little over an inch wide to heat where the crease in the center goes. There are also two reverse creases which goes from the forward center diagonally towards the wing trailing edge. This method works very well though there is a learning curve in using the heat tape.
    Agreed. I did that with my full-door plexi. Just make a form that will allow the plexi to settle by gravity to the desired shape, put the the tape where the bends are, plug it in, and have a cup of coffee while the plexi settles into position.
    Gordon

    N4328M KTDO
    My SPOT: tinyurl.com/N4328M (case sensitive)
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  33. #73
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    Quote Originally Posted by Gordon Misch View Post
    Agreed. I did that with my full-door plexi. Just make a form that will allow the plexi to settle by gravity to the desired shape, put the the tape where the bends are, plug it in, and have a cup of coffee while the plexi settles into position.

    You can do it without the heat tape, just lay something on either side to block the heat like 2 yardsticks half an inch apart and heat the gap with a heatgun where you want the bend. Practice on some scrape first

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"
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  34. #74
    skywagon8a's Avatar
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    Quote Originally Posted by Gordon Misch View Post
    Agreed. I did that with my full-door plexi. Just make a form that will allow the plexi to settle by gravity to the desired shape, put the the tape where the bends are, plug it in, and have a cup of coffee while the plexi settles into position.
    Don't leave the heat tape on too long! Don't sip that coffee. Too long can make marks in the surface or depending on your form shape it can over bend.
    N1PA
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  35. #75
    Gordon Misch's Avatar
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    Yep, just long enough to achieve the desired shape. Maybe the coffee should be a small cup - - -
    Gordon

    N4328M KTDO
    My SPOT: tinyurl.com/N4328M (case sensitive)
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  36. #76

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    Quote Originally Posted by stknrddr View Post
    Lunch Time Aviation - Project Update



    Click image for larger version. 

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    A photo of a piece of scrap plywood in place just to see what it looks like.
    I have not decided what to do for the back of the baggage compartment.
    Maybe I'll install tabs to attach a similar plywood sheet, or install
    a canvas style back; or the lower half of the back may be plywood,
    while the upper half is canvas?
    Any thoughts and photos of options are appreciated.

    Thank you,
    John
    john, I'm really enjoying your progress reports, you're a true craftsman.

    re rear baggage: i ended up going with .050 alum and added a couple stiffeners, I have an underseat storage tray and Atlee "safari seat". The center underseat storage "hatch" has since been fitted with piano hinge. Had the surface powder coated with a textured finish for non skid effect. Holding up well.

    Click image for larger version. 

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  37. #77
    stknrddr's Avatar
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    Project Update - Ribs and Spars
    I am beginning to think about wing assembly, and I have placed
    a set of my scratch built ribs onto a set of spars. But first,
    a quick update on my turtle deck and stringers.

    Click image for larger version. 

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    The three stringers are now in place. Pulling 3 string lines,
    and fabricating the bulkheads (stations) to the strings worked well.
    The stringers shown here are currently clamped to little saddles welded
    onto the bulkheads in the above photo. The stringers will later
    be pulled riveted to the saddles.

    Click image for larger version. 

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    The photo above is a saddle used to cradle the stringer in place
    on the bulkheads. The saddle is made from a piece of steel tube.
    The saddle gets welded to the bulkhead, and then the stringer gets
    riveted to the saddle. I needed to add a little spacer to the bottom
    of two of the saddles to ensure the stringers were nice and straight.
    All other attachment points for the most part were perfect.
    We are using aluminum tubing for the three stringers on the turtle deck.
    It's light in weight, has a radius for the fabric to wrap nicely around,
    and could be bought locally at our local steel supplier (no shipping charges).
    We used 6061-T6 Aluminum Tubing, 1/2" diameter, and 0.049" wall thickness.
    The bulkheads are 18" apart on center, and it appears that the tubing will
    be stiff enough, pending control when a person shrinks the fabric, not to
    distort it.

    Click image for larger version. 

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    The photo above shows the saddle welded to the bulkhead,
    and the stringer cradled onto the saddle, followed by a couple
    of pull rivets later.

    Rust Prevention

    We use a light oil (air tool oil because it was handy) to prevent rust,
    as rust tends to develop first on the welds, and later on the tubes.
    We lightly wire brush any areas where rust is forming,
    then coat the clusters and lightly coat the tubes as needed.
    The entire fuselage will be cleaned prior to paint.

    Click image for larger version. 

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    Ribs and Spars

    It's pretty cold here in Wisconsin these days and my shop is not heated,
    where I am working on my wings, so I can only make small progress
    on my wing assembly. I can do enough in my cold shop to at figure out
    what I have to either fabricate or purchase to continue.

    Click image for larger version. 

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    Here's a photo of my ribs set on my spars. My friend Charlie
    who is also building his own scratch build SuperCub with me,
    picked up these 24 gallon wing tanks. He found enough for
    two sets of wings. We'll need to pressure test them. We
    bought the spars from Javron located in Brainard, Minnesota.

    Click image for larger version. 

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    I built a one piece rib for quick and easy assembly.

    I plan to fabricate the compression members (drag struts),
    however I can not fabricate the drag and anti-drag diagonal wires
    due to the threads needing to be rolled (not cut). I'm on the look out for two
    sets of wires, new or good used sets.

    My next step on the fuselage is to fabricate the upper doors (windows),
    as the fuselages are located in a warm shop. More to come as these develop.

    Thank you for viewing, and Happy New Year on this January 1, 2018.
    John
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  38. #78
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    Nice work Oliver.
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  39. #79
    RVBottomly's Avatar
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    I agree. Looking very good.
    Thanks stknrddr thanked for this post

  40. #80
    stknrddr's Avatar
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    SuperCub Sunday Progress


    The following shows progress on my Upper Doors:
    Click image for larger version. 

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    I'm going with swing out Upper Doors on both the right and
    left sides of the fuselage. To fabricate the Upper Door frames,
    we rotated the fuselage onto it's side, and clamped a flat board
    flush to the outside of the fuselage. By the way, I'll install those
    little flip out window vents on each side, so we won't necessarily
    have to require on opening the upper door to get some air,
    as a lot of wind will come in when the upper door is opened.

    Click image for larger version. 

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    I used plywood spacers to dictate the gap between the Upper Door
    frame and the fuselage tubes, and cut and fit the tubes as shown.

    Click image for larger version. 

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    Steel blocks were used to hold the tubes in place during the cutting,
    fitting and tack welding process.

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    The Upper Door was removed from the fixture for finish welding.

    Click image for larger version. 

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    Here's the Upper Door clamped in place to check the fit.

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    I want the Upper Door to be flush to the outside surfaces
    of the fuselage, so small boards were clamped to the
    outside of the fuselage, then the Upper Door Frame was
    clamped to the boards. After the door is positioned correctly,
    the hinges can be welded onto the door frame.

    Click image for larger version. 

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    A piece of piano hinge is cut to length and placed as shown.
    The hinge will be permanently welded to the door frame,
    then either riveted or screwed to the cross member
    (nut plates required) on the fuselage. The hinge gets tack
    welded to the door frame in place as shown above.

    Click image for larger version. 

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    After tack welding, the door frame is removed,
    and Charlie finish welds the hinges.

    Click image for larger version. 

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    Here's a photo of the hinge on the other end of the
    Upper Door frame. I think I can now start to consider to
    weld the "D" shape window frames onto the fuselage, and
    figure out how to trim out all the way around the door
    opening for a positive stop and for gap sealing.

    Engine Selection - People ask me all the time "what engine?".
    I appreciate all the engine discussions on this site, and I
    read them all. With the understanding that I want to keep
    this plane light, and without flaps, I hope to find a C-90.

    Thanks for looking, and I appreciate the feedback.
    John
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