Hey guys, this thing you're doing sounds great. If I wasn't a poor college student and actually had stuff lying around, this would be the first place I'd go.

This is more of a request, because I could seriously use some information/advice.


I'm an ARO (aerospace engineering) majoring freshman at Cal Poly Pomona and on a whim decided to join a Design-Build-Fly club at my school where we :ahem: design, then build, and then fly a plane in a competition hosted by the AAIA. Since it turned out that I had the most experience with electric motors (from my experience with ground-hugging vehicles) the whole matter of propulsion for our plane has dropped into my lap. This includes what electric motor to use, which batteries and yes, prop choice.

This year's competition requires a huge, heavy plane to be powered by a max of 3lbs of batteries and by a motor that is limited by a 40amp fuse. :O

The most difficult mission we're going to fly requires us to load two 4.4lb water bottles, fly around a short 2000ft course, land, load another water bottle, fly a lap. land, load another bottle and so on to 5 water bottles for max points. That’s 22 lbs of water. We figure our design (a high-wing dual boom looking thing, looks exactly like the plane from Flight of the Phoenix) is going to weight about 8 lbs. Add water to that and you get 30lbs max. The design currently has a 9.5 ft wingspan.

We can't use LiPoly's either.

I'm seriously not sure what motor, batteries or prop i should go with. Since were not caring at all about speed, I guess a huge propeller would be good, The fuselage’s diameter is going to be about a foot n a half. With landing gear figured in, we should have clearance for one monster of a prop.

With something that large, using an electric motor would probably require gear reduction? Maybe? Is it possible to create about 7lbs of thrust (what the seniors say we'll need) with a 40 amp limit and around a 26 volt limit? (I get 26 volts from being limited to 3lbs of batteries, which means a max of 24-26 Sc cells).

I'm sorry I don't have an actual straight foreword question, I'm just digging for any information. Any ideas and or suggestions would be greatly appreciated. Basically, I'm looking for somewhere to start at, to start experimenting with.


Thanks a lot!