I am converting a glow kit to electric and need some input on battery selection. The airplane has a 52 inch wing, 497 squares, semi-symetrical airfoil. I am wanting to use a geared Astro-Cobalt 025 that I have available. Looking for mildly aerobatic performance, nothing unlimited. What kind of weight should I shoot for and what battery size/cell count would be a good place to start? I'm an electric newbie so go easy on me. Thanks, Chad.

Hi Chad, Let us know what the weight is on this craft, so we can determine the wing loading. That'll make alot of difference in power selection. Also, a good rule of thumb on batteries is (1) cell for every 50 sq", which would put this one at 10 cells. Also another rule of thumb is 50 watts of power for every pound of weight.
You'll get there!! Jim

Thanks for the reply Jim. The box says it should weigh in at 3.75 to 4.5 pounds with their prototype being closer to the 3.75 mark. I can and will do some lightening but I don't want to go crazy if I don't have to. The airplane is a Great Planes Taylorcraft by the way. Thanks again, Chad.

Chad, Try to keep your weight to 38 oz (which would include your radio gear). What you'd be looking at with the following set up would come to a total of 4.5 lbs. This combo used with your geared AF 25G will give you about 335 watts @ 22 amps. This comes to about 75 watts/lb to give you mild aerobatics.
(you have a matching ESC for the motor, right??)

(14) sanyo# CP1700SCR cells
11X8 APC electric prop

Good luck and let me know how it works! Jim