Back when the Firebat was new, there was lots and lots of complaining going on about how it wouldn't fly, but nobody was trying to do anything about it. People were content to simply drag Great Planes through the mud and condemn their entire product line. Nobody ever bothered to check if the motor was a 6V or 7.2V Speed 400.

It sounds like it's the 7.2V Speed 400. On Great Planes's recommended 7-cell pack, it's no wonder the plane won't fly. To get decent power out of a 7.2V Speed 400, you need a 10-cell pack.