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Old Aug 04, 2012, 06:49 PM
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Hot glue held together by foam
United States, WA, Vancouver
Joined Aug 2010
4,141 Posts
Originally Posted by DuPageJoe View Post
I'm hoping I have enough pop in my motor to get good flying on my full sheet Super Easy. I've added the reinforcing tape, spar and motor mount, and wanted to pass on what I've found about the weights these add.

Iíve decided to use my 4 mm CF tubing for the spar, since a piece of 3/32 inch music wire fits inside. I made the center joiner out of that wire and bent it to fit the wing dihedral, then I used 30 minute Epoxy glue to hold the assembly together. I made each arm 12 inches long to fit about 18 inches back of the nose, as shown in the picture, and it weighed 11 grams. When the Epoxy cured, I put a little quick drying (white) Gorilla Glue where the spar would sit on the wing and taped it down with the Scotch Extreme shipping tape.

I used some leftover Epoxy to help hold the motor mount in a groove on the top sheet of the nose. I also put some of the Gorilla Glue in the bottom of the groove. The motor, prop and mount assembly weighed 80 grams (2.8 ounces). I was careful to match the prop tips to the 15 inch line in the slot. I needed to trim the bottom corners of the ďfirewallĒ to match the dihedral in the wing.

The motor is a Topstar 2810-01C I found at a manufacturerís booth at the Model Expo a couple years ago. The picture in Post #130 shows it a bit clearer. Itís made by Shenzen Topband Ltd.. Specís on line claim 150 watts power and Kv = 1200 rpm/V. In a test with a 9X5 prop, claimed current draw was 16 A from a 3S LiPo. Itís a little heavier than the one in the Dynam package from Hobbypartz. I like the well fitted look of it, but Iím not sure where to get another. Iím using an APC 7 X 5 E prop which should give me 17 ounces of thrust, if I can coax 10,000 rpm out of the motor under load.

When I taped the front edges of the wings and keel, I added a 12 inch long bamboo barbecue skewer to each, with a little Gorilla Glue drizzled behind the skewers. The three skewers weighed 6 grams. Total tape, not including the hinges was about 180 inches long and weighed 37 grams, about 2 grams for every 10 inches. The tape made a good job of confining the foaming glue under the spar and the skewers. Just donít use too much GG.

Between the taped edges and the rest of the reinforcements, I added 54 grams, not quite 2 ounces this time. The motor assembly added another 80 grams, totaling 479 grams, a little less than 17 ounces. The whole assembly balances at about 17.5 inches back of the nose or 3.5 inches back of the target. I have about 6 ounces more electronic gear, including the battery, to distribute to get it all in balance. Next step will be to fit the servos.
Looks like it's all coming along GREAT! When's the maiden ?
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