I don't know what to say more, just try some nicad cells. Sometimes the Nimh cell will not put out more than 20 amp or the voltage will dump to nothing. Put a voltmeter on the pack when you run it up and see what is the voltage of the pack.

Try two packs of 7 x 1700's or 7 x 2400 nicad and see. If that does not work, send me the plane and I will try to make it fly!!