Quick question for you experts, Im taking a $15 guillows balsa plane kit (24 in wingspan) that was designed for rubber freeflight and converting it to rc for fun. Anywho, its a fairly small plane and I noticed other people who make planes around this size use 7.2 volt 6 cell batteries around 270mah. My question is, would their be any problem using the 6 cell 7.2 volt 900mah batteries that I used for my aerobird challenger? The only difference is increased mah which Im guessing should give about an hour of flight time on this little puppy! Is there any obvious problems with doing this?

the only issue I can see is weight. My guess is that the 900mah battery will be quite heavier than the 270mah.

What motor/gear box/prop combination are you thinking about using? I have my eye on one of their laser cut 24" span models, but I have not yet begun the research into a power system. Ideally I would like to use a brushless set up with a lipo battery pack; any suggestion?


Regards
Jaime.

I have an MPS-1A motor system from DJ Aerotech in a Guillows' "Arrow" rubber band contest free flight kit, with a 2 cell 250 mah Li-Poly pack. Just added a small rudder and elevator on the tail section, with some small carbon rod pushrods (because I just happened to have carbon rod---small music wire would work great. too). A pair of Pico servos and GWS R4P receiver, Pixie 7P ESC. Flies around at less than 1/2 throttle cute as can be!! Can be trimmed to fly in a beautiful slow climbing turn hands-off. 45 minutes flying time!!!
Their MPS-2A (twin motors driving a common prop shaft, wired in parallel) would be a great choice for such a conversion for models a bit heavier, such as the Guillows scale kits in the size you mention. Combined with a 3 cell Li-poly 250 pack, it would definetely do the job at much less cost than any brushless system.
If at all possible, go with Li-Poly power. The weight savings on small models like this has a HUGE effect on performance. Weight is extremely important on this size plane.

That plane was designed to fly at less than 2.5 oz as a free flight plane. The succesful conversions fly well at about 4-6 oz. The aerobird batteries weigh more than that. Even if it could fly, the wings would fold under stress. If you want to build a plane for the aerobird batteries that is not a lead sled, then you have to build a plane that is as big as an aerobird challenger. Your only hope in using those batteries is to take the kit plans to Kinkos, scale them up 50% and build the plane from the plans. If you want to build small, then you need to look into two cell lithium polymer batteries in the 145-340 mah range.

The Arrow comes out at 2 3/4 ounces RTF. GOT to keep 'em light.