Folding Struts 101

For all that fly scale Cubs know that transporting the struts sometimes can be a problem. Easy fix; have them fold flat against the wing!  Instructions are for 1/4 scale but can be modified for other scales.

Toggle nut, butterfly nut
Toggle nut, butterfly nut

What you will need extra that is not in the kit
4 rods with 4/40 threads on one end 30 inches long made by Dubro #145
4 4/40 solder on threaded ends by Dubro #336
4 4/40 ball links, the ones that are solid on the end by Dubro #497
4 4/40 threaded rod end cleaves by Dubro#302
8 2-56 bolts with nylon insert lock nuts 1/2 inch long by Dubro
4 3-32 E/Z adjust Aileron Horn by Dubro
1/2 foot of small silicon fuel line by Dubro
4 small butterfly nuts or toggle wing nut, can be bought at Ace Hardware
2 x 4 inch section of sheet metal
2 3/4 stream line aluminum tube by K&S
2 5/8 stream line aluminum tubs by K&S

Starting out

  • Look over the paint chips in the photos below as it’s just normal hanger rash from 4 years of use.
  • You need to disassemble the butterfly nuts, cut the center section out and the two halves should separate. We will be using the narrow one for the job.
  • Insert the ball link between the ears of the butterfly nut. Washers may be added to fill in space between the ball and the ears. Insert bolt through the hole in the ear and tighten. Assemble all four units.
  • Drill a hole in each between the ears, this will all a 4/40 screw to attach it to the wing. Now screw a 4/40 rod in to each ball link about 3/4 the way in.
    You will need the plane set up with the wing on. Not required but I recommend taking a 4/40 tap and cleaning the threads out of the clevis.
  • Now screw the solder on end in to the coupler about 3/4 the way.
  • Take the strut mount tabs that are supplied with the kit and insert the 4/4/0 threaded couplers on them and mark the holes. They should fit side by side with very little gap between them.
  • Drill the holes and reinsert the couplers and install screws.  Now install the mount tabs and the 4-40 rods that where made above on the plane.

strut10

Strut

  • Now swing the rods up next to the solder on end and trim the rods to length.
  • Removing one rod and coupler at a time and solder the end on. It helps to work on and complete one side at a time from now on to keep from getting parts mixed up.
  • Now remove the couplers from the rod. Cut several section of fuel tubing (about 1/4 inch long) and insert them on the rods about every 6 inches. This keep them from vibrating in the stream line tubs.
  • Take the K&S streamline tubing and cut to length, large one up front and small in back.
  • For the end that attaches to the wing I filled the end of tubing with 1/2 long section of hard balsa carve to fit the tube.
  • On the fuse. end I used a long section of wood so the I could taper it down to where the rod extend out of the tube.
  • CA balsa in place and drill hole for the rod in both ends. Wing end will require a large hole to all the tube to fit flush with the ball end.
  • Now reinstall coupler on to rod ends and install complete assembly on plane.

Jury Strut

  • The bends and length of the parts below will need to be made custom four your plane.
  • Take the K&S sheet and cut 4 strips 1/4 inch wide about two inches long.
  • Next step will take some guesswork; you may want to use card stock to make a template. What is required is to make a band the will go around the strut the will hold the aileron horn. You will need one for the front and one for the back.
  • After band are made you will need to drill holes for the 2-56 bolts. Now assemble band on to struts with the aileron horn in place and snug the bolt. The horn should rotate freely on the bolt.
  • Take s section of 3/16 OD tubing and measure off for the cross strut smash the ends and mark the hole locations.
  • For the front jury strut flatten the end of the tube and bend forward, and for the back one you will need to bend the tube back drill holes and mount to wing.
  • Bring the front and back jury struts in and trim to length. Next flatten the end of the tube and mark holes for attachment to the struts.
  • Insert a screw from the plane side through the aileron horn, cross strut and the upper strut. Install a nylon lock nut and tighten. Now repeat for other side.

  • Disassemble the jury struts for painting. Remember to keep each side separate from the other.
  • Main struts can be paints as they are, just mask the threads on the end that attaches to the fuselage side.
  • After all is painted reassemble Jury struts.
  • Before attaching the bracket on the strut for the Jury strut wrap a small section of black ribbon around the strut and assemble.
  • Attach struts to the plane.
  • To remove the wing, I remove the two 4/40 bolts from the bottom of the fus. that hold the alumni strip to the plane. Unfasten you wing and pull straight out.
  • Remove the 4/40 bolts that attach the jury struts to the wing, fold the jury strut toward the fus and fold the whole assembly down.
  • I made a guard, by taking a small square of 1/16 ply and cut a square (as seen below).  Drill holes so they match up with the screw holes for the jury struts.
  • Use the jury strut screws to attach the guard when folding the struts.  This will protect your wing and keep the nuts from poking into the wing covering and protect the finish.

Look at photo page below for help. Contact me with any questions.

www.thecubden.org

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