Dragonfly Wing ModPosted by Hacks & Mods Blogger on Saturday, 14 April 2007
Contributed by Scott Monsma (milw)
I've been wondering how easy it would be to make replacement wings for the Dragonfly, mainly because I want to make it look different, better, maybe even cooler! The stock wings appear to be made of a very thin plastic, clear Mylar perhaps? The 'veins' are carbon fiber rods, 0.036" diameter, very close to 1 mm. At the root of the wing, the rods are covered with what appears to be heat-shrink tubing, so the portion that plugs into the wing-holders, or shoulders, is about 0.058" diameter. Out of the box, each wing set (the upper and lower wing for one side) weighs about 2.2 grams.
(if you can't bear to read all this, here is a short video of RedWing in flight)
At the local hobby shop, I found carbon fiber rods were available in two lengths, 24" and 40". Since the rods on the leading edges of the wings are 8" long and the angled rods are 7", a full set of wings needs at least 4 x 15" or 60" total. I decided to go with the 40" lengths since that will have the least waste- one used for the 4x 8" leading edge rods and the other for the 4x 7" angled rods. Unfortunately, the shop didn't have the exact sizes to match the stock parts, and since I didn't have shrink-wrap tubing that small anyway, I decided to go with 0.05" diameter rods, since that should easily fit in the holders.
Next up was the wing material. For my first attempt, I used a plastic toy store bag. It seemed a bit too stiff, especially side-by-side with the original wings. Also, it didn't look cool enough- just plain, matte, translucent white. Next I tried a party supply store, where we get mylar helium balloons for birthdays. After walking up and down every aisle in the store, I finally found the mylar sheets in the tissue paper section! I would have preferred rolls, but the closest material on rolls had a paper backing and seemed too thick (but it was cool- silver foil hologram patters on the front). So, I settled for packs of folded sheets. I couldn't decide on the color, so I ended up buying metallic blue, metallic red and iridescent. Each pack has 3 sheets and a single sheet is big enough to cut 2 and a half full wing sets, so I shouldn't run out for a while! And, at $2.50 per pack, that's 33 cents per wing set. Not bad, it helped to make up for what I had spent on the carbon fiber rods (about $2 for each 40" rod).
Tips for cutting:
- Use a high-speed cutting disk in a Dremel or similar power tool to cut the carbon fiber rods. Don't try to use a knife, wire-cutter or saw, since these will crush and delaminate the carbon fibers. Watch out for loose fibers- they are very sharp and can easily poke you. I had pretty good results using a fine sandpaper on the cut ends to remove the burrs.
- For the mylar sheet, use a new Xacto #11 or other sharp utility knife. It's best to hold the sheets down with a ruler or other flat object close to the line you are cutting. The mylar can tear, and it's also very slippery. Sharp scissors will work on a single sheet for fine tuning the shape.
Here are my cut materials. It turned out that the folded mylar was perfect for making a stack of two wings- one fold at the leading edges and one fold in the center. I just laid the old wings on top for a template, marked the straight edges, and then sliced through the 4 layers with the Xacto knife. Then I carefully cut the rounded back outer corner, again holding the whole stack down very close to the knife point, so the layers didn't shift. I still had trouble cutting all the way through the bottom layer, so I had to use the scissors to trim afterwards. I cut the carbon rod as noted above, with a cutting disk in the Dremel. Here is my stack of cut materials (along with a pair of larger iridescent wings from an earlier attempt).
I used the narrower type of shiny scotch tape to attach the rods to the mylar. It might be better to look for something even narrower to save weight, but I just used what was at hand. The rods and the mylar are attracted to static on the tape, so I found it best to hold the tape taut and lower one end onto the carbon rod (lying on the table), then to bring the other end down of the tape down so the rod was centered. I also put a ruler down on the mylar, parallel to where I wanted to attach the rod. I again lowered one end first, then got the other end lined up and lowered it onto the mylar. Here's my setup before attaching the first rod at the leading edge (bottom of picture):
Here is the first completed wing. You need to look closely at the stock wings to reproduce them. Note that the two leading edge rods are offset by about 3/16". I attached one rod right at the front edge of the mylar and folded its tape strip down and around in half; it's the lower one in this image. The upper rod, I laid with the edge of the tape at the front edge of the mylar, so the rod is set back from the edge by the right amount.
Next- note the reinforced area at the rear corner of the stock wings- there is a small hole punched through, to allow attaching the rear center of the wings to the pin on the Dragonfly body. I used 1/2" pieces of tape on the top and bottom of each wing, again marked the location of the hole by laying the stock wing on top as a template, then used the Xacto to cut the small hole. It ends up being 4 layers of tape and 2 layers of mylar, so be careful cutting. I had to flip the wing over to finish cutting. Finally, there is also a reinforcing strip of tape that crosses the angled rod and the leading edge rod, and is wrapped from the top to the bottom of the wing. I used 1.5" pieces of tape here. (note- I'll make & post a line drawing showing more clearly the tape and hole locations; that will be full size and useable as a template). Here is the set spread out so you can see the holes near the center crease:
And here is the Dragonfly after attaching the first wing set:
The next set I made in the identical fashion- unfortunately, since I wanted the rods to be under the wings! I should have flipped the second mylar sheet before attaching the rods, as a result, one side has the rods on top and the other side underneath.
Here's the final result! Now for some flight testing!