ORIGINAL: garywi
. I saw the guy that owned the black twin engine warbird (that crashed last year in a race) who had bought a battery mount to use two RC car packs. Can't find it on the internet.
Gary that would be Tony P. who owns the Valley Hobbie shop in Chino Valley near Prescott.
There Is a 14.4 volt geared unit on the commercial market but I prefer 16.8. Thats probably the one you saw. Most of us now just use a cheap starter and the thin plywood legs are easy to whack out with almost any kind of tool. Its a big advantage to use just about any kind of pack whenever you want. Boxs are unnessasary weight and complexity.
Sorry I answered earlier but the morning server at this site always times me out without time to think and type.