Author Topic: Attn: Electrical Guru's - Small Electric (Read 1606 times)

CircuitFlyer · « **on:** March 01, 2015, 06:57:59 PM »

Our club is proposing to host a 1/2a (.09 cu in Max) multi-engine profile scale competition this summer. The purpose of the contest is to tweak peoples interest in building scale model aircraft. The idea is to keep it simple for everyone to get involved - no throttle control, no flaps or retracts, etc. I would like to have the club think about adding a separate class for small electric powered aircraft to the contest. By definition 1/2a is a class of displacement of internal combustion engines only, that's why electric power would have to be a totally separate class. Apples and oranges can't compete with one another in the same event.

Question: What would you suggest as the limiting criteria to apply to the electrical power system to limit the overall size of the aircraft to approximate the size of 1/2a glow powered models.

My suggestion - motors: no more than 1 oz in weight. Bare motor (no prop adapter, no mount) with wires & bullet connectors. Batteries: maximum 3S lipo's or 12 volts for other types.

Keep in mind this is scale not speed, racing or combat. It's multi-engined models so could be a B-17 or a Spruce Goose. Some might want to even try electric ducted fan scale jets.

What are your thoughts?

Crist Rigotti · « **Reply #1 on:** March 01, 2015, 07:46:57 PM »

Quote from: Silver Dart on March 01, 2015, 06:57:59 PM

Our club is proposing to host a 1/2a (.09 cu in Max) multi-engine profile scale competition this summer. The purpose of the contest is to tweak peoples interest in building scale model aircraft. The idea is to keep it simple for everyone to get involved - no throttle control, no flaps or retracts, etc. I would like to have the club think about adding a separate class for small electric powered aircraft to the contest. By definition 1/2a is a class of displacement of internal combustion engines only, that's why electric power would have to be a totally separate class. Apples and oranges can't compete with one another in the same event.

Question: What would you suggest as the limiting criteria to apply to the electrical power system to limit the overall size of the aircraft to approximate the size of 1/2a glow powered models.

My suggestion - motors: no more than 1 oz in weight. Bare motor (no prop adapter, no mount) with wires & bullet connectors. Batteries: maximum 3S lipo's or 12 volts for other types.

Keep in mind this is scale not speed, racing or combat. It's multi-engined models so could be a B-17 or a Spruce Goose. Some might want to even try electric ducted fan scale jets.

What are your thoughts?

Limit prop size to 6 inches for true 1/2A (.049)

Tim Wescott · « **Reply #2 on:** March 01, 2015, 08:50:44 PM »

It's really hard to equate electric with glow, so you're not asking an easy thing. Some suggestions are:

Limit the total aircraft weight, with batteries. Maybe limit span & length, too. Let the pilot put whatever they want on the plane. That plus scale realism should keep the power systems from getting nutty. To establish the limits, have a bunch of people report in on what they fly with their 1/2-A motors.

Limit the battery total energy (cell count times capacity). E.g., a three-cell 400mAh pack, or a four cell 300mAh pack, or a 2-cell 600mAh pack all carry (roughly) the same energy (and weigh about the same).

Limit the motor weight. I wouldn't suggest this for racing or speed, because some bozo would figure out how to spend $$$$ to get just a bit more -- but there's no big advantage for scale.

CircuitFlyer · « **Reply #3 on:** March 03, 2015, 08:11:25 PM »

Thanks for the ideas guys.

Tim, I like your idea to cap the battery total energy. I was thinking that may work best if you also awarded more points for longer flight time. That would help keep the power reasonable. 5600 mWh limit (per motor) and 5 points for each full minute of flight.

Paul

Author Topic: Attn: Electrical Guru's - Small Electric (Read 1606 times)

CircuitFlyer

Attn: Electrical Guru's - Small Electric

Crist Rigotti

Re: Attn: Electrical Guru's - Small Electric

Tim Wescott

Re: Attn: Electrical Guru's - Small Electric

CircuitFlyer

Re: Attn: Electrical Guru's - Small Electric