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Sep 16, 2018, 06:27 PM
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My Espada boom repair

I broke my Espada R boom this year at SU. Hard landing and a straight and clean complete break about 8 in forward of the tail. Did not have much angulation so no effect on the control rods. I thought I would share my repair for critique and the benefit of others. Here in these pics you see the break, stabilized by 90deg aluminum formers (available at Lowes/ HD). The Espada has a midline web/ bulkhead in the boom that I hope to incorporate into the repair, so I made dorsal and ventral longitudinal cuts into the boom where carbon stock will be epoxied. Hoping they will somewhat glue into the midline web. My repair techniques are mostly from the RadioCarbonArt/ Paul Naton Glider Repair Lab videos, which are excellent and I highly recommend. The first vid and particular the chapter on materials and their use would be useful to everyone in the hobby.
Last edited by ddavis72; Sep 16, 2018 at 06:44 PM.
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Sep 16, 2018, 06:31 PM
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Repair (cont)

Here you see the CF rectangular stock epoxied (BVM aeropoxy) into the groves. The proud part will be ground down. The close fitting part of the break was infused with thin Ca. The portion of the break where there is more of a gap was infused with aeropoxy. The boom already feels pretty strong after this was done. Be careful not to glue in the rud or ele rod.
Sep 16, 2018, 06:35 PM
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Espada repair (cont)

Here you can see the CF longitudinal brace stock sanded down. A small defect was left in the fuse. I cleaned it up with a bit and devised an internal kevlar patch glued in with thin ca. Updates to follow. I will be sanding down approx a 4 in area (2in either side of break). I will be repairing with unidirectional CF cloth (longitudinally) using the resin/ peel ply/ compression wrap technique. Incidentally, I buy my composite repair supplies from Fibreglast. They sell small amounts of material in "swatches" that work well for RC repairs I've found. I've bought carbon, fiberglass, kevlar and peel ply from them.
Last edited by ddavis72; Sep 16, 2018 at 06:42 PM.
Sep 19, 2018, 04:13 PM
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Boom repair (cont)

Filled in the little defect with BVM aeropoxy and milled fiber and then added my first layer (2in) of the CF cloth wrap. Added resin below and on top of the CF and then did the peel ply wrap followed by compressive wrap with rubber therapy bands secured with tape. The CF layer comes out of this very smooth, little excess epoxy, and needing very little sanding. I hoped for a 2 layer repair here but realized after the fact that my 2 in CF wrap here has the fibers oriented circumferential and not longitudinal so I will add 2 more layers on top of this with the fibers in the correct direction and increasing in length to cover the 4 in sanded gap. The peel ply technique results in very little thickness added to the repair even though I used resin above and below the CF wrap.
Last edited by ddavis72; Sep 21, 2018 at 08:25 PM.
Sep 26, 2018, 02:25 AM
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Boom repair

Repair after last CF layer and some sanding, then slathered with Bondo glazing putty for sanding.
Jan 31, 2020, 12:14 AM
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Boom after repair, filling, primer and sanding.
Jan 31, 2020, 12:19 PM
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rockbus's Avatar
Your Espada repair is much nicer than my efforts.
Jan 31, 2020, 09:55 PM
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Well thanks!

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