I'm interested in getting a Roadkill, and was wondering if I could use the ray-o-vac 9v with it..?

From : Don Stackhouse

Once again, too heavy. The Ray-O-Vac weighs about 1.3 ounces. The battery we recommend for the single-motor Roadkill models is a 7-cell pack of the "Double Time" 110mah NiMH cells from John Worth's "Cloud 9 R/C". It weighs only 1.0 ounces. That extra third of an ounce for the Ray-O-Vac could potentially turn your airplane into a flightless car, good only for taxiing. At 2.8 ounces flying weight the single-motor Roadkill models fly great, at 3.0 or 3.1 ounces they fly a bit sluggishly, and at 3.3 ounces they might not fly at all.

The P-38 has a bit more surplus power, but once again the Ray-O-Vac is not a good choice. It has a lot of weight for its capacity, and for about the same flying weight you would get better performance and longer flight times from the battery we recommend for the P-38, a 7 or 8 cell pack of the 170 mah NiMH cells from Batteries America (E.H.Yost).

A 7 or 8 cell 110 mah "Double Time" pack will also work with the P-38; the performance is spectacular, but you only get about 3-6 minutes from the smaller cells, depending on how good you are at throttle management. Of course, after keeping that little rocket ship within the confines of an indoor basketball court, you'll probably be ready to give your brain a rest anyway!

Don Stackhouse
DJ Aerotech