It was winter here on the homestead and with the temp at many degrees below zero and snow slowly piling up, I wasn't spending any time at the flying field. Having built and flown the Gladiator XL, I decided I wanted to do build another Crash Test Hobby (CTH) wing. I spent a few evenings browsing the various EPP foam wings on their website and frequenting the RCGroups forums for those specific wing projects. One of my goals was to try and use a new motor and ESC from the spare parts bin. And with a variety of various Li-Po batteries on hand, finding one that would work well with the wing's power plant would also save me more money.
After juggling motor weight, current draw, prop size, and other numbers around, I decided to try the 57" Titan wing. One of the features that drew me to this particular wing was the narrower wing design. This allowed the Center of Gravity (CG) to sit a little further back which makes it easier to place the components and not have to use additional weight to aid in balance. I dislike dragging along extra weight that does nothing except adding grams to the all up weight of the aircraft.
The wing build videos that Crash Test Hobby links from their website do a very good job detailing the build. I'm including a few photos to show how I did a few things in my Titan construction. I am not commenting on all of the steps I did while constructing my wing. This is NOT a substitute for the build videos provided by CTH.
This is the 4th wing I've assembled and I've used this technique of pinning the wing halves together with big "T" pins. I cover my blue Styrofoam "pinning board" with a piece of wax paper so the glue doesn't leak out and attach the EPP wing foam to the pinning board. The Titan wing is a semi-symmetrical airfoil which allows it to lay nice and flat on the pinning board.
I use white Gorilla Glue, activated with water, for joining the wing halves together. It expands as it cures. When I pin the wings in position, I insert the pins at various angles to help ensure the foam won't move while the glue cures. Here you can see some of the excess glue that works it way out of the seam. It is easy to trim away the excess with a hobby knife or sand it if you prefer. Using Gorilla Glue, instead of hot glue, helps keep the build weight down. The lighter the wing, the more fun it is to fly.
Here is the trimmed up glue seam. As you can see, the Gorilla Glue cleans up nicely. It is very strong to say the least.
After I mark and cut the slots for the spars, I use a combination of hot glue and foam glue. I put foam glue in the slot first and then tack a small section of the spar into position using the hot glue, making sure the spar is well embedded in the EPP foam. With the hot glue firmly holding the spar in position, I then run another bead of foam glue over the top of the spar. Yes, it takes much longer for it to dry compared to using only hot glue but it also saves weight. Remembering that this is a mid-winter build, I have plenty of time for the foam glue to cure.
With the spars embedded on both the top and bottom side of the wing, the formica plates for the supplied motor mount are glued into position. After that, the shock cord is glued into position around the entire perimeter of the wing. Finally, the heavy duty packaging tape is applied along the leading edge and over the spar areas. When you flex the wing at this point, you'll notice that it is much, much stiffer than when it was only the Gorilla Glue holding the two wing halves together.
More Titan Wing
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