Dragonfly Construction Tips
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Home > Articles & Tips Index > Kit Modifications > Dragonfly Construction Tips

[Courtesy of Pete Young, pwyoung "at" ix.netcom.com, June 2001]

We've gone through quite a few Dragonflies (from Diversity Model Aircraft) the past two years at MIT and I've built quite a few myself. So here's some free advice, just remember that you get what you pay for :)

Landing Gear. The original kits had the wire LG on the front bulkhead and the latest kits have the wire moved back to a second former. I suggest clamping this assembly and pinning the laminations together with servo screws or something as this takes quite some abuse. It's worthwhile to change the wire to the next larger gauge as the stock wire tends to deform easily. If you do use the stock LG, consider the following. a) run a light rubber band between the wheels to prevent the lg from spreading. b) don't use the kit's supplied wheel collars as they are needlessly heavy - a turn or two of copper wire or something similar will act fine as a wheel retainer.

Fuselage. Cut through the laser cut nibs with a sharp blade so the ply pieces don't start shedding pieces. I prefer bonding all the fuselage joints with carpenters glue as c/a doesn't bond well to the polished wood and somewhat marginal joints; and if the carpenters' glue joint does come apart, there's a nice glue fillet there that takes kindly to c/a.

Tail Pieces. Substitute lighter wood if the kit wood is heavy. Use c/a paper hinges. Add triangular pieces (1/8" balsa) to either side of the vertical to keep it from falling off.

Linkages. Don't even think of knotting the line to tie it off. A technique suggested by some guy named Fritz is to use thin sections of aluminum tubing - run the line through the tubing, then through the control horn, then back through the tubing, tension, then crimp the tubing. If it's not perfect, uncrimp and recrimp. Use one piece of line that runs from the control surface through the servo arm (wrap it around the servo screw) then back to the control horn.

Wing. Run 2" to 3" clear packing tape from tip to tip, one piece. Dust the adhesive side first with 3M77, apply while still damp. I suspect that if you do this, you can eliminate the fiberglass tape on the center section. Put a 2 1/2" to 3" piece of hardwood (coffee stirring stick or popsicle stick) on the TE to prevent the rubber bands from chewing on the TE.

Other mods. A 2.5:1 gear box will allow you to turn 9 - 11 inch props and dramatically improve static thrust. Even better is to drop the dihedral to 5 deg or so and rig ailerons on the wing. If you do this, you can eliminate the rudder servo. The APC electric props are really terrific btw.

Pete Y

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