Foam Leading Edge Repair

I decided to repair the dinged up leading edge on my Habu and share the process.  At my flying club we do electric group jet fly’s  About 10 of us were in the air one nice July evening, one of the newer pilots lost control for a second and went over our heads.  We all ducked and fortunately he regained control and didn’t hit anyone or anything and saved the model.  In the mean time, I looked back up and unfortunately, flew the wrong jet.  I quickly realized it was not my Habu and looked around the sky (Bad feeling)  in time to see the Habu heading straight down.  I chopped the throttle and pulled full up surprisingly, it recovered to a straight up heading but found the edge of the tree line and branches.  The plane was in good shape but had (as my friend Barney Say’s) “Kazooties” on the leading edges of the wing. A the time I wanted to try the Habu2 which featured a brighter color scheme.  So I retired the Habu to the basement rafters. Jump ahead a few years, my friend Tim needed a jet so I decided to touch up the old Habu.  Tim is the Chief Flight instructor at my PMAC club.  He does a lot to help new pilots.  I felt my old jet would be a good gift for him.

The material I used for the repair were :

15 minute epoxy, Foam safe Glue and kicker, Micro Balloons (TOPR1090) , Ezcote (DLMB37), Clear packing tape, Tissue paper, scrap 1″ pink foam, Hobbico “Hobbylite” White filler (HCAR3400)

Tools: Perma grit SB280 sanding block, #2 X-acto knife with #226 Whittling Blade,150 sand paper, 320 sand paper, throw away brush, Bondo Squeegee, Latex or foam safe paint.

Depending how bad the damage to your model is you can choose from the following methods.  The three I use are:

#1 Light damage: Hobbico Hobbylite filler sand to shape.

#2 Deep ding but not wide: New Pink foam sand to shape.

#3 Wider damage with scuffs and dings: Micro balloons and filler.

#1 Light damage.  Sand the area with 150 paper.  Apply the filler, a little “Spritz” of water first helps this water based filler to flow out and spread easier.  Let dry thoroughly, like a few hours.  Then sand with 150, don’t sand really hard just get the shape right then switch to the 320 paper to finish.

#2 Deep ding but not wide.  For this type of damage I like to replace the “divot” with 1″ pink foam and then carve and sand to shape using very little filler.  I cut out the damaged area in a square fashion then I cut a pink foam piece to the same size and shape, test fit then glue into place. You can use epoxy or foam safe glue.  When dry; carve (#226 blade) to shape and then using the fine side of the of the SB280 block block sand to shape then use 150 and 320 sand paper.  You may not need any filler but if you do fill the edges and finish off like we did in step #1.

#3 Wider damage with scuffs and dings: Micro balloons are used here.  Sand the area first with 150.  I put clear shipping tape along the bottom of the leading edge of the wing sticking out about 1/2″ past.  This works like a “Dike” to stop any  overflow of epoxy/micro balloon mix.  Mix the 15 minute epoxy and the add micro balloons.  I like to add the balloons till the mixture is near “Peanut Butter” thickness.  Now Squeegee the mixture into the dings and dent.  Put as much as you can without over filling the damage.  Let dry for about 20 minutes and then peel away the tape.  The glue balloon mix should still be a little soft but not sticky.  If it is real sticky wait longer.  With a new sharp Xacto blade trim any extra filler on the leading edge. It is easy to trim to shape now versus when the glue mix is fully hardened.  Let the wing dry for a few hours till hard and sand-able.  Note: Epoxy will dry faster if you find a warm 75+ degree area to dry.  When dry use the SB-280 to touch up the leading edge area.  Now use a good coat of the Hobbico “Hobbylite” White filler, fill the entire leading edge are using the squeegee to level it off.  Apply a good coat of filler to the bottom..  When dry block sand (SP-280) coarse at first flipping to the fine to finish her up.  Sometimes you need to repeat the filling step to remove any low spots.  When the leading edge is nice and smooth add a 2″ wide strip of tissue with the EZ Kote finishing resin.  1″ on top rolled around to the bottom.  This adds strength to the leading edge and averages out the repair areas slightly.  When dry sand lightly with 320 paper and apply another cote.  When dry paint the area with Latex paint, I used a Gray Behr house Latex paint.  Timmy was surprised to receive a (Almost) new jet.  We had fun flying together.

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That night and we managed about 8 different jets in the air together. Zoom!