hi there:

Although I have not done the conversion on a butterfly, most 100" std class sailplanes (and the butterfly is not too different from a sailplane) will respond nicely to the following:

one of the axi 28xxyy series of outrunners, a CC phoenix 35 ESC with Castle link, and a 3s lipo or 10 cell nimh pack (or several packs) for power at 2000 mah or so, a Cam folder prop 12x8 or so from HL, and a Triton Charger will round out the equipment list very nicely.

I have been flying Epower for about 18 years, and the above list is a great way to go for success. For a plane at 3.1 lbs figure that you will add about 12 to 16 oz to the plane.

For reasonable leisurely climb you need 50 watts per pound of plane. So figure 175 to 200 watts minimum. Bump that to 100 watts per lb and the phrase "climbs like a homesick angel" applies quite well. Even more.... oh,dear me!

The folks at HL can get you hooked up very nicely. IMHO, dont let them sell you a jeti ESC, buy american, buy Castel Creations.

ciao -rjf