Micro X Quad

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Mini quadcopters have become extremely popular due to their portability and robustness. I felt like taking it one step further and downsizing to a micro (nano?). The hardest part about building something this size is sourcing some decent, brushless micro motors. I wanted to use a maximum propeller size of 3 inches and keep the weight under 100g.

The only candidate I could source was the Hobby King AD-C5 3700KV micro motors. These motors are definitely tiny and light, weighing only 4.6g!

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To match those tiny motors I’m using the Hobby King F series 6 A ESCs. They weigh just 6 g, are SimonK compatible and can be programmed using 1.27 mm pitch pads lined up in a row. Most importantly, there was few reports of them browning out under load.

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Stripping down the ESCS to flash them.

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I needed to make up a light wiring harness.

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Soldered together the wire pairs.

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Soldered the corresponding sides together and applied heat shrink.

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I cut the wires to length and soldered to the ESCs, leaving as little slack as possible to save on weight.

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Soldered the motors to the ESCs. The motor wires are covered with enamel. I find the easiest way to remove the enamel is to heat up a ball of solder and dip the enamelled tip into the hot solder ball until fumes stop rising. The propellers are a very tight press fit.

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Heat shrinking the ESCs.

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Attaching the motors to the frame.

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Plugging everything in. To save on weight I repurposed the stripped down receiver from the PUMQ and soldered it directly to the Naze32.

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Done.

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It weighs about 104.9 g.

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Performance is a little average. Hobby King’s specifies a max thrust of 90g, however it takes approximately 70% throttle to hover, leaving very little leeway for acrobatics. This could be improved by removing the frame parts that obstruct the blade flow and reducing the weight of the frame. At the moment I can’t recommend these motors due to their deficiency in quality, high cost and low return.

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Parts:

AUW 105g
3-5 minute flight time.

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