Spinner for folding prop on RC model aircraft

thingiverse

This adapter enables you to connect two folding prop blades to a budget-friendly drone-style brushless motor, perfect for powering a fixed-wing aircraft. In my case, this setup drives a homemade motor glider with a 160cm wingspan, producing an impressive 600g of thrust at 12,000rpm from a 7.5x4 inch folding prop. This is enough to give my plane an excellent climb rate. These drone motors are mass-produced in huge quantities, which is why they're so affordable despite their decent quality. As propeller connectors, they feature a simple M5 screw bolt protruding at the top. Since they aren't designed to drive larger props, it's wise to limit the maximum rpm from your RC transmitter to prevent overheating the motor. My setup could produce significantly more thrust at higher rpm, but I decided that 12,000rpm is a suitable number, as centrifugal forces increase with the square of the rpm, and the thrust was just fine for me. A word of warning on using this adapter: all parts of a propeller are subject to significant centrifugal forces. A single 3.1g lightweight blade with a center of gravity only 4.1cm from the axis, spinning at over 10,000rpm, exerts a pulling force on the spinner exceeding 10kg. That's why I've thoroughly tested this adapter. I've loaded it (and even a slightly smaller version) up to 32kg with a weight scale, which was the maximum load before my test stand gave way. I wasn't able to tear apart this adapter during my tests. So I know that my printed part can handle these forces well. I strongly recommend doing the same if you print and use it. I won't be responsible if your propeller disintegrates, which can be seriously hazardous. Caution must also be used when selecting the bolts that hold the propeller blades. I absolutely do not recommend using pieces of filament, although it's easy, fits well, and can be fixed by briefly touching it with a hot soldering tip. At my tests, the filament bolt gave way at 15kg, so this is really only suitable for very small planes (e.g. indoor slow flyers). My clear recommendation is to use metal pins (e.g. small steel nails) as bolts. I had some leftover nails from an IKEA kitchen back-wall kit with about 1.8mm diameter and cut them to an appropriate length. To secure them in place, I used a super glue brand that I know works exceptionally well with PETG (which is far from the case for all brands). This adapter has been thoroughly tested in real RC flight situations, and it performs exactly as expected. I developed it as part of a new 3D printed RC plane that I'm currently working on, which I'll publish soon here.