ORIGINAL: Yak18

Try shoving the throttle stick to the upper right corner of the transmitter. This will give you full throttle and full right rudder to counteract all the torque you just imposed on the airplane. When the plane starts heading to the right as speed builds up, move the stick back toward the center until it stops turning right. This sounds crazy but it works. I've taught many people to takeoff taildraggers using this method. After 2-3 attemps they're takeoff rolls are arrow straight.