cornellworm

I need a motor that is less than 4" in diameter, extremely powerful (the most important property), and hopefully not to heavy either? any advice? and also how many lithium batteries would i need to run this plane for around 20 minutes?

volkan

brushless met MOST of your expectaions
but 20mins, thats mad

Jim Finn

My Feedback: (2)

Maxcim Motors makes what you want.

Jean13704

Look in the Power Systems forum on RC Groups. They have a lot more discussion of e-flight than does RC Universe.

DBCherry

My Feedback: (4)

You are ready to shell out over $300 for the motor, speed control and battery pack, right?
Dennis-

CafeenMan

Probably more than that. My buddy just spent $175 on Li-Poly's for a small electric motor but his plane has unlimited vertical for at least 15 minutes. He says he can fly it twice having full power when he wants it or three times if he does fewer vertical maneuvers. And the plane is lighter than when he had NiCads that only gave him 8 minutes of good power and 12 minute flights.

I don't know jack about electrics, but I'd think the motor alone would cost over $300 when he says "most powerful available."

DBCherry

My Feedback: (4)

Probably right Cafeenman, not to mention that he'll prbably need to use battery packs with at least 20+ cells. Don't know if the Lithium cells would handle the current loads.
Dennis-

Duane-RCU

My Feedback: (5)

I think this is the one they advertised at having as much power as a .90 four stroke....look at the bottom of the page, it will fly a 12 pound plane... http://www.hobby-lobby.com/brushless_axi.htm

dieselfume

Astro flight makes some motors that will meet your needs. A cobalt 40 with a gearbox can move around a 18+ lb plane on 20-24 cells. If the cells were, say 10000mAh and you propped it to draw ~25 to 30 amps (say a 16x14) in flight you could go 20+ mins. Astro flight makes a 60 and a 90 motor that can take 32-36 and 36-40 cells repectively (NiCD cell counts, convert accordingly for LiPoly). The same size cells (but more of them) on a cobalt 90 propped to 25-30 amps could move the same plane faster than a 40 could or same speed, but larger. Being brushed motors makes them more affordable.