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Workshop Build-Along — Sopwith Camel — Part 27: Interplane Struts

Workshop Build-Along — Sopwith Camel — Part 27: Interplane Struts

The last bits of building in any project seem to take the longest, at least when you have a deadline to meet! We are planning to have the compete construction article for this sport scale WW1 classic in the upcoming December issue of MAN in our Scale Special Issue.

To make the interplane struts you can do it before or after the model is finished and painted, and we did it after since the process is the same, just make sure to protect your finish from any solder drips. I used tape and thin 1/64 inch plywood placed between the wing and the brackets.

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Start with a strip of 0.060 inch thick K&S Brass and cut into eight 2 inch lengths. I used a pair of tin snips but you could use a fine tooth hacksaw if you like.

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Sand the edges smooth and then round off one end as shown above. Sanding the edges smooth is very important as it prevents cracking when you bend the parts.

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Place the strip in a vice and use a hammer to tap each piece to bend it 90-degrees. You want the short end to be about 1/2 inch long. Now mark the position of the attachment holes centered on the short end as shown above.

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Drill the 3/16 inch hole and de-burr the edges of the hole on both sides.

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I used 6-32 stainless steel caphead machine screws to attach the end pieces to the wing’s hard points.

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After estimating the rough length of the struts, make four 1/4×3/4 inch basswood strips  then cut a 1/16 inch wide slot in each end to match up with the end pieces.

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You will need to make a holding jib, (I used scrap balsa and spruce), to hold the wing panels at the correct incidence angles. The jig is held in place with rubberbands and to find the proper length of your struts, measure the distance between the tops of the screws holding the brackets in place.

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You can use the same jig for both wing panels.

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Here are the right interplane struts slipped into place. Adjust the angles of the ends of the struts for a neat appearance and make sure the brackets do not bow the slots open when you tighten the bolts. Note the end pieces face inboard toward the center of the wing.

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Remove the wood struts after finalizing their length and solder the X-bracing wires to the four L-brackets. I use 1/16 inch coated welding rod wire as it is easy to bend and solders nicely. Make sure the attachment screws are tight to prevent them from moving. I drilled 1/16 inch holes in the inside corners as shown and bent the wire ends 90 degrees to fit into the holes. I soldered them in place with Stay-Brite High Silver content solder with liquid flux. Drill a couple of random holes in the brackets and roughen up the surface so the epoxy will bond properly to the metal.

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It is also important to bind and solder the X-bracings where they cross. This locks them in place and adds a lot of rigidity to the struts.

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After staining the struts, use some 15 minute epoxy (I use Z-Poxy from ZAP), and then tape each of the struts in place. Allow the epoxy to fully cure before removing the struts from the wings. Leave the first set of struts in place, remove the jig and reattach it to the opposite wing panels. Now, repeat the process.

stryt1

After you’ve build both sets of interplane struts, remove them from the model and use a Motor-Tool and a cutoff disc to trim away the access end piece from the struts. Remember to clean all the flux off of the solder joints. Sand smooth and give the struts a couple coats of clear to protect the finish.

strut2

That’s it, this process is not difficult at all and it produces a pair of precisely sized strut assemblies for your model that fir perfectly.

Part 28: http://www.modelairplanenews.com/blog/2015/06/09/its-all-in-the-details-the-little-things-that-count-on-a-scale-airplane/

Updated: February 12, 2016 — 12:43 PM
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  1. I really like how you took what to me is a pain in the butt process and made it look easy. I will try this to make a couple of extra struts for my Balsa USA SE5-a. Thanks.

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