Wednesday, January 05, 2011

Review: Art Applewhite - Whirlwind Monocopter (24mm)

The Whirlwind Monocopter is the 18mm Dragonfly's bigger brother and flies on 24mm motors. I had the opportunity to build and test a beta version, which was known as the Cyclone. The differences between the beta and production models are minimal.


Construction:

Wing: Basswood, 2" x 10" long
Balance Beam: Long dowel
Center, Center & Motor Supports: Basswood and short dowels
Motor Mount Tube: BT-50 tubing
Motor reinforcement: Fiberglass drywall tape

The construction of this kit was simple and similar to the Art Applewhite 18mm Dragonfly. The following materials and tools are required: Elmer's Glue-All, hobby knife, scissors, ruler, drill with 1/4" bit. I substituted carpenter's glue for the Elmer's.

Here's a summary of the steps:

1. Assemble center hub
2. Add supports and balance beam
3. Glue wing on
4. Assemble motor mount, including fiberglass tape wrap
5. Glue mount to hub
6. Drill launch rod hole

At the end of each step, heavy fillets are applied to all joints.

Finishing:
Finishing is optional but at least a clear coat is recommended. I used Helmsman Spar Urethane.

Flight/Recovery:
Prep consists of centering the motor in the mount, adding a tape thrust ring, and friction fitting. You can use booster motors or sustainer motors with short delays. It flew off of my standard pad, which happens to be similar to that described by Art (plans included in the instructions and on his website). I already had a 1/4" stubby monocopter rod. I flew mine twice on a D12-P and an E9-4. The D12 flight was nice, but the longer burn E9 was fantastic! The winds were heavy and they did travel a ways downrange, but the walks were short when compared to any rocket with anything that resembled a chute.

At burn-out, the monocopter flutters lightly to the ground. I found that the side of the E9 had burned through just above the nozzle. Because of the length of the motor vs the motor tube, this did not damage the model. It may have reduced the performance toward the end of the burn.