Attached is 1:27 gear ratio to speed up the rotations. The output shaft will have contra-rotating feature, what that means is outer part of shaft rotates in one direction and inner rotates in other direction. So when I attach propellers to it, they will run in opposite directions.
The gearbox file is attached. You can use it and make the output shaft with inner and outer arrangement for contra-rotations. Inner shaft will have 1:27 rotations and outer will also have 1:27... Which will make both turning in opposite directions double the speed.
This will be turned by hand, so provide the handle too. I'll make 3D print of this.
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