Hey everyone! Long time RC aeromodeler & drone flyer/builder here. I also have background in elec engineering. And now a new Paramotor pilot. Just wanted to chime in with my 2 cents on this OpenPPG project. IMO airplane style props are not the correct style for this application. Drone props may not be the best for this application either but IMO they are closer to what this project needs to have nice trust plus good efficiency. Remember, drones don’t just hover. They can pitch fwd and move along at a decent rate of speed too. IMO a done prop with a low pitch (around 4-5), and a wider blade towards the hub / narrower towards the tip would provide the right combination of good trust and efficiency. I feel airplane props are not good for this application because their design was intended to where, after takeoff, where the prop is pushing or pulling the weight of the plane fwd to a good rate of speed, the prop is said to start to “unload”. At that speed the propeller just needs to provide some trust to keep the plane moving fwd without crating a ton of aerodynamic drag. On a Paramotor we do not travel fast enough fwd to have this unloading effect happen. So similar to a drone, the props are mostly always nicely loaded.
IMO the setup on this Paramotor is way too inefficient. The whole power system is drawing way too much current for it to be worth switching over from a gas motor Paramotor. But… there is a light at the end of the tunnel. IMO, bigger motors (same diameter stator but taller stator, almost double (MAD M17) @ same Kv rating) coupled with a drone style prop would provide (I’m guessing) around a 30-40% increase in flight time with similar trust of the stock power system. And who knows, maybe even more… Another thing that needs to change is the prop mounting method. The drone “T” style prop mounting (which the MAD motors are capable of) would benefit this project greatly. The “T” style (2 small bolt) retaining design lessens the rotational mass of the motor/prop combo and also provides waaaay better security of a prop becoming undone in flight. All of the motors are using right hand threaded locknuts, and that’s fine for 2 motors in this setup. But the other 2 motors which spin against the threading rotation of the prop locknut risk the possibility of undoing the nut in flight. Especially at takeoff which is when the props are spinning at their peak RPM of a normal flight. An acro pilot would prob put even more stress on this situation as they rev the engine high/low/high/low more often.
Let me know what u guys think.