I think you are focusing on the wrong thing.

You need to check the specs on the ESC... which states....

"Compatible with 7-14 cell NiCd/NiMH, and up to 4 LiPo cells. Works with Outrunner and Inrunner Brushless motors"


The voltage to the motor is varied as needed, so it has to be able to handle voltages at LEAST as great as what the ESC puts out, with a large margin for safety. Usually the windings are heavier on these RC motors so that they can tolerate the higher burst currents without burning out the wire.

So you should be able just to plug in a 3S or 4S Lipo into this plane w/o problems.

I remember reading that this was one of it's salient points.

Check the review here at RCU where the reviewer did just this.