Saturday, April 1, 2017

Electric Toothbrush Aircraft - Fly Toothbrush, Fly!

It flies!

First Flights - including aircraft point of view from onboard micro video camera:

Youtube Playlist - 5 videos with subtitles so click the "CC" control.

Part 1 - The Motor
A local supermarket has started selling low cost electric toothbrushes that are noisy and powerful so of course that sets me thinking - can this thing fly?

Part 2 - The Propeller
Aiming here to design a low cost kit - the motor unit, switches, propeller (and optional micro video camera) can be re-used for each group of learners. The aircraft and some accessories probably need to be new for each group project at a cost of about USD 10

Part 3 - The Balancing Act
We test that the aircraft flies in its original state as a "chuck glider".
Then find the centre of gravity by balancing the aircraft with one finger under each wing. Mark that because we need it to balance in the same place after we add the motor.
The first attempt to fit a motor is "super nose heavy". Try again mounting low so the battery can fit under the wing. This time it balances. Then some work with rubber bands and a cut piece of pencil as a peg to hold it in place.

Uncontrolled free flight is a bad idea when this can go "wild" for 4 minutes of running time. Possible simple controls are a timer to give a short running time, or some kind of tether like "control line" or "around the pole". Or both timer and tether. We go here for the "around the pole" tether as the simplest method. We use monofilament fishing line. Size 0.45mm has worked here. We tie the end to the motor rear mount and line it up with a wire loop taped to the wingtip. The pole bearing is a cut piece of garden hose joiner spinning on an 8mm bolt.

Part 4 - Fly Toothbrush, Fly!
If flies! First flight gets 3 times around the pole. Flight02 does 4 circuits and we have a "PlaneCam" operating.

Part 5 - Endurance
Flight 3 is 3rd time lucky with 3 minutes of flight. Less wind seems to make a big difference. With maker discussion and commentary. Ideas to get better include (1) reduce weight by removing the micro video camera .. (2) experiment with a smaller power unit and a smaller aircraft because a scaled down version could work well indoors and learner workshops will need that option.

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