Brush motors are hard on Lipo batteries, you need a brushless setup. You need one anyway, the old fashioned brush motors wear fast, and in a few summer months, cost more than a BLDC. Just use it as is until you learn some, but on the second motor, get a brushless dc motor. It will not fly very high with the nimh battery, don't climb up and risk running out of power if it will, just hover low with it and practice.

Look for the setting up a stock Walkera 36 thread here somewhere in this forum, and trust it.

SB