Way over-engineered pull-copter v3
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**Update: See [Pullcopter V4](https://www.thingiverse.com/thing:7346852), which is currently entered into Thingiverse's [Take Flight Challenge](https://www.thingiverse.com/challenges/takeflight).**
I thought it would be fun to design a pullcopter toy with over-engineered features, that is, interesting improvements that aren't necessary for the function of the device, but may (or may not) improve the performance. This design makes use of three of my other designs:
* [Tilted-sinewave gear cutting](https://www.thingiverse.com/thing:5285589)
* [Ergonomic handle](https://www.thingiverse.com/thing:5330170)
* [Elliptical-blade NACA airfoil propeller](https://www.thingiverse.com/thing:5300828)
The over-engineered improvements include:
* Designed to assemble without tools or fasteners. The handle assembly snaps together.
* Ergonomic handle based on actual anthropometric measurements of human populations, described and cited [in my blog article about building the handle](https://www.nablu.com/2022/03/whose-hands-are-biggest-you-may-be.html). The handle can also have finger grooves, but I don't recommend this because then it fits only one specific hand size (see below).
* Custom-cut gear using asymmetrical gear teeth (smooth sawtooth using a skewed sinewave profile). The idea here is that the forces on the gear teeth are just one-way, so eliminating the symmetry decreases the pressure angle of **both** meshing teeth, and increases the strength of the tooth in the force direction.…
