.40 size conversion: what size battery?
 

I'm planning to convert my .40 size 3d glow airplane to brushless power. I've already been through a lot of this forum and eflite's website, and still haven't found an answer to this question: In a .40 size 3d plane with a 650kv motor at 22.2 v, pulling 50-60 amps, what capacity of battery do I need for an 8-10 minute flight? Anyone, anyone?

RE: .40 size conversion: what size battery?
 

I am running 6S 3000 on a 830kV, 11x5 prop, and get a good 7 minutes with some to spare on the batts. In a 40 size superstick. and 2 minutes more on my 3600's.

I run 2 3S in series. Usually end voltage is 11.18v

hope that helps

RE: .40 size conversion: what size battery?
 

Thanks. It definately gives me a starting point.

RE: .40 size conversion: what size battery?
 

I am building anelectricTelemaster and plan to use a couple of 3000 mAh 3S in series, or maybe just one 6S.

A .40 motor is equivalent to about 1 HP or 750 watts. At 22 volts this is 750/22 or about 35 Amps. Since the Lipo is 3 Amp-hrs of capacity, it would last about3/35 * 60or 5 minutes at full power (discharge rate, C=11.6). If you are planning 3D flight then you might be running near full power 80% of the time so you might want to go to 5000 mAh 6S, or two 3000 6S in series. There are several combinations possible. I like the 3S option because I can use the same battery in other smaller and lower voltage planes.

Art

RE: .40 size conversion: what size battery?
 

art,

did you mean 2 3000 6s in parelell ? as 2 6s in series would be way to many volts :D .

RE: .40 size conversion: what size battery?
 

Oops - I meant two 3000 mAh 6Sin <u>parallel </u>for a total of 6000 mAh at 22.2V.

By the way, I have never powered anything that large before so I'm just going by theory and not practical experience. However, I am building a large Cessna 182 (12 lbs) and have been thinking about the options for it. I may base it on the 0.60 equivalent in electric (975W). Since I plan scale flying, a couple of 5000 mAh 6s seems like a good choice for me. 8 to 10 minutes of flying before landing is my goal.

Art