Battery Cage Mod
Author Email: MMCGinnis at RCGroups
I had a problem in which I had to apply a lot of rudder trim to keep the thing straight. A quick inspection of the bottom of the heli revealed the culprit. When the battery is slid into its holder, the upper side of the battery cage that presses against the top of the battery is deflected upwards. If your battery is just thick enough (as mine was) it deflects the cage high enough to press against the bottom of the center prop shaft.
This causes excess drag on the shaft, causing extra rudder trim. Iím sure it also caused a decrease in flight time, but I have not timed the difference. I noticed that when I removed my battery, it had a nasty crease right down the middle of it after the very first flight. I simply used my Dremel tool to grind off a bit of the battery cage protrusion (see included pics).
You can see how there is a good sized gap between the battery frame and the prop shaft without the battery installed. When it is installed, the gap is gone. After filing the area and inserting the battery again, the gap is now there, though not as wide as it once was. Hopefully this will not crease the battery any further. The battery cageís grip on the battery is still more than sufficient to keep the battery from sliding out on its own.