Barring the smallest manned airplanes, most plane which can be pulled round by a prop have variable pitch propellers. The explanation for that is easy effectivity. Inner combustion engines are best at a particular RPM, and as an alternative of giving the engine extra gasoline to hurry up, pilots can merely change the pitch of a propeller. With a gasoline powered engine, the mechanics and design of variable pitch propellers are properly understood and haven’t actually modified a lot in many years. Including variable pitch props to one thing pulled round by an electrical motor is one other matter fully. That’s what [Peter McCloud] is constructing for his entry to the Hackaday Prize, and it’s going into the best mission possible.
This mission is designed for a earlier Hackaday Prize entry, and the one 2014 Hackaday Prize entry that hasn’t killed anybody but. Goliath is a quadcopter powered by a lawnmower engine, and whereas it’ll hover in [Peter]’s take a look at rig, he’s not getting the carry he anticipated and the management system wants work. There are two attainable options to the issue of controlling the decapatron: an ingenious software of gimballed grid fins, or variable pitch rotors. [Peter] doesn’t know if both answer will work, so he’s engaged on each options in parallel.
[Peter]’s variable pitch rotor system is mainly an digital prop mount that connects on to the pushed shafts on his gas-powered quadcopter. To get energy to the electronics, [Peter] is mounting everlasting magnets to the quad’s body, pulling energy from coils within the rotor hub, and rectifying it to DC to drive the servos and electronics. Management of the props will likely be achieved wirelessly by way of an ESP32 microcontroller.
Variable pitch props are the usual for every thing from puddle jumpers to acrobatic RC helis. Within the quadcopter world, variable pitch props are at greatest a footnote. The MIT ACL lab has achieved one thing like this, however maybe one of the best comparability to what [Peter] is doing is the unbelievable Stingray 500 quad. Flite Take a look at did an amazing overview of this quad (YouTube), and it’s extraordinarily just like a future model of the Goliath. An enormous motor (within the Stingray’s case, a brushless motor) powers all of the props by way of a belt, and the pitch of the props is managed by 4 servos. The maneuverability of those variable pitch quads is unbelievable, however because the Goliath is so massive and has a lot mass, it’s uncertain [Peter] will likely be doing flips and rolls along with his quads.
You’ll be able to take a look at a video of [Peter]’s construct under.