Nice job on the Panther Mike. Like you I went with a separate power for the receiver. I used a 3 amp Hobby Wing BEC. I would also agree with you that the retracts could be an issue. I have finally installed them on mine and dumb luck has got them working properly. There might be another issue that has come up with my Panther.

In the process of testing the retracts, the shaft on the stock motor bent. It came out of balance someway(I am still not sure how). Needless to say one of the blades on the rotor is a bit shorter than the rest. Pulling the motor out was fairly easy as the unit shook itself apart. I replaced the stock motor wit a HET 2W. I managed to balance the stock rotor, but was a little disappointed with the results. The stock rotor was replaced with a HET 6904 rotor. It fit better than the original rotor did. There is a lot less gap between the blades and the housing.

When I tested this configuration(I haven't tested for thrust), the modified readings using 2 Zippy 3s 30-40c batteries hooked in parallel were 65 Amps, 670 watts@ 12.3 volts. Stock configuration was 62 Amps @ 12 Volts (thrust was 1.3 Kg as tested at the factory). Stock the fan unit weighed 8 ounces, and the modified unit weighs 5 3/4 ounces. There seems to be even more thrust now. Some time in the future I will test for thrust.

I weighed the plane with the stock motor setup and no retracts at 43 ounces. With the modified fan, and retracts I measured 45 ounces. I haven't had a chance to test the modifications yet as it hasn't stopped raining for a couple of weeks now, but the weather is supposed to clear this weekend so we shall see what happens.