Will my 1 ounce kokam 560 mAh li-poly pack work well?

It seems to be the same weight as the NiMHs you recommend. Now that I have lighter batteries, using my pico stik gear on a RK model looks more feasible....

From : Don Stackhouse

Depends on the model. We haven't tested these ourselves (yet, but we plan to soon), so I'm reluctant to make a recommendation. However, I have received a report from customers with Li-poly batteries in RK models who had successful results. Is that 1 ounce for a 2-cell pack? If so, that's about halfway between the weight of a 7-cell 110 pack and a 7 cell 170 pack. Provided that you can get at least 5000 to 5100 rpm at full throttle, that should work. The current should be in the neighborhood of 1 amp at that rpm.

The voltage of a Li-poly 2 cell pack is less than a 7 cell NiMH pack, which reduces the rpm and the available power. However, if you can get enough rpm, then the power being delivered should be enough to fly the plane.

The same is true of the twins, except your cells need to deliver twice the current. 2.0 amps at full throttle may be adequate, and 2.5 to 3.0 is better. From what I'm hearing, the new Li-poly cells may be able to handle that.

In the past our objections to lithium cells were that they were simply too big and heavy, and that they couldn't deliver the necessary current. The new cells seem to be much better on both of those issues. The other problem was the lack of economically priced chargers for them (I have reservations about recommending a $300 charger for a $50 model!), which also seems to be improving. We're in the process of acquiring some cells to test ourselves.

In the meantime, my answer is "maybe". I'd recommend starting with one of the more efficient RK models for your first try, such as (in order of preference) the Cub or the Junior, the long-wing Zero, or maybe the Corsair or the Jenny. In twins I'd recommend the Electra. All of these do reasonably well at reduced throttle settings and seem to be fairly tolerant of weight.

Don Stackhouse
DJ Aerotech