How to build an EPP Racing Wing

I want to start by saying that I absolutely love foamboard planes, but I've found that their durability isn't quite what I'm needing when I am racing. EPP foam is known for its strength and durability, it can withstand quite a hit. There are many companies that make good quality EPP wings. This article is covering how to build a TBRC Reflex38, the best racing wing out there in my opinion. If you've never built an EPP wing before it can be a little daunting, but I'll do my best to help show you how easy it actually is.

TBRCwings have provided a detailed build manual on their website www.TBRCwings.com and they have produced a great build video series that you can watch here. https://www.youtube.com/watch?v=xvWyZCgRpRk&list=PLYEC3GJn9iNd3MwJDnKDcmtGuWJTPpbYj

If you're a fan of pictures and detailed instructions then continue reading. Any questions you have I can answer them at the bottom.

TBRC Reflex38

Start off by checking you have all the pieces. Lay them out on your bench and you'll get an idea of what goes where. You will also need some Gorilla Glue, Goop, a knife and a covering iron (a household iron could work, but a hobby iron is a good investment)

We start by adding Gorilla Glue inside the hole in the blunt section of the wing. Gorilla Glue is a must for the main spar as it expands and penetrates into the foam giving you a super strong bond.

Then drizzle some Gorilla Glue into one of the wings. It will expand, but you dont want to skimp on the Gorilla Glue.

Pour a few drops of water into the wing, and this will start the reaction with the Gorilla Glue. You'll need to start working fast.

Apply some Goop, (or some more Gorilla Glue, up to you) to the blunt section. Don't apply it to the wing as you'll put it on places where it won't match up with the blunt. This saves you from a messy clean up.

Now slide the blunt with the spar through it into the wing. Once it's in the wing twist and wiggle it around a bit to help spread out the Gorilla Glue inside the wing and to make sure the Goop covers the whole side of the blunt nicely.

Do the same for the other wing and once you've pressed the wings to the blunt section use pins to securely hold it in place. I recommend leaving this to dry for 24 hours to get the strongest bond possible.

Now it's time for the fiberglass spars. We have 3 of them to install (2 long and 1 short), and these will help make the whole wing super rigid so it can withstand the huge flight forces you'll be subjecting this wing to when you're racing. On the underside of the wing, mark a line that is 1 inch back from the leading edge for each wing and then a line 1.25 inches back from the nose on the blunt section. Cut a slit on each of the lines about half an inch deep.

Push your fiberglass spars into this slit and they will almost completely disappear into the foam. They will almost completely disappear once the build is finished. Make sure when you're pushing the fiberglass spars into the wing that you don't run your fingers down the spar. Push it in bit by bit. Otherwise you could get fiberglass splinter and that is absolutely no fun. Squeeze some thin CA into the slit after you've installed the spars and you can use some kicker to speed up the curing process.

I've painted the motor mount here as I am going for an orange colour scheme on my wing this time. You'll notice that the motormount is a little short of the back of the wing. You can either glue it where it sits or you can cut in a little shelf to match the motor mount. This is a little fiddly but it adds a ton of extra strength to the motor mount.

With the motor mount installed it's time to laminate. Before we actually start the laminating process, I recommend you give the whole wing a light sanding. Although the wing will come to you nice and smooth, the melted surface will not stick well to the laminate. I find sand it a little bit so that it is a little bit fuzzy, almost like denim jeans, Laminate will stick nicely to this finish.

I like to start on the bottom. Lay the laminate out flat over the wing and using your covering iron start by making a strip down the centre of the wing. Once the strip is done then work your way outwards to go over the whole wing. Try not to leave the covering iron sitting in the one place for too long as you have a chance of melting the foam and warping your wing. 

 Once the plane is laminated you can use a knife to cut it out for the equipment bay.

One thing you will need to do is to cut out the back corner of the wings to fit your propeller. Lay your propeller in what will be its final position and cut out enough foam back from the motor mount so that you will have at least half an inch clearance on each side of the prop.

Trim up the elevons to match the back cut in the wing. This helps the aerodynamics and also helps to make the plane look snazzy.

The elevons are made from good quality balsa wood, but as they are they aren't super tough. Using some laminate that you'll have left over, cover both sides of the elevons. This will help make them slippery and much stronger. Some people like to do 2 coatings of laminate, but I've found 1 is enough. This is up to you though.

Once the elevons are laminated, cut 4 strips of laminate that are about 1 inch wide. Starting on the underside of the wing lay one of the laminate strips across the hinge line of the elevon and laminate that to the wing. With the elevon now attached on the underside flip the wing over and place a strip over the hinge line on the top and laminate that on too. Be sure to flex the elevon to its maximum position when adding the laminate strip, this will ensure that you'll get full motion throws once you've got them attached. I like to use laminate hinges rather than tape as laminate isn't sticky until you apply heat. This allows you to position it exactly right.

The elevons can be attached with hot glue or Goop. I used hot glue on this build, but I like using Goop when I am going to be flying in the hot summertime as I don't want them falling off after leaving my plane sitting in the sun too long. 

Mark out spots for your servos in the wing and using a knife cut into the foam and pull out the foam to leave enough space for the servos. On this build I was planning to put a GoPro up front. For most builds I recommend putting the servos as far forward as you can. This will make it much easier for you to balance the plane on the CG mark. The CG mark is 140mm from the nose. Which just happens to be the back of the equipment bay hatch, so when laying out your servos if you can get them in front of the back of the hatch you'll have a good time. Once the servo is installed attach your control horns and pushrods.

Now attach the coroplast hatch onto the top. Some people just tape it in. I like to cut into the bottom side 1 flute in and this makes the coroplast a nice hinged door. 

Not shown here, but install your motor on the back and then install your FPV gear and you're ready to race.

The CG is 140mm from the nose. Get it to balance right there and you'll have no troubles flying this amazing plane.

For the motor I recommend an NTM 2836 2200KV with a 6x4 prop. With a 4s battery you're going to be winning a bunch of races with your friends!

Overall you should have a smooth build of this kit. The next one I build, I'll make sure to mount my servos further forwards as having them this far back definitely made balancing the plane on the CG tricky. Also when adding the winglets I think if you scuff up the coroplast a little bit you'll find your glue will hold on much better. Although I haven't had one rip off yet (fingers crossed). Also when you go to laminate the plane, I suggest testing the temperature of the iron on the small corners you cut off when you cut the space for the propeller. This way you can make sure you're not going to melt the foam, yet you have enough temperature to get a good adhesion to the foam. It should be difficult to pull the laminate off the EPP scrap.

The photos used in this build tutorial are from the build video linked at the top of the article. kindly provided and authorised for use by Yuvski.

To learn more about this awesome wing go to www.TBRCwings.com

Best of luck out there

eagle4