rear motor support

[GriffinRU]

The idea behind rear support is to keep motor in proper alignment with gears. Failure to do that means:
- losses (wear) in gears
- unnecessary stress on motor shaft. motor housing, mounting bracket, chassis...

Now, do you need it? I'll say yes. At the end decision is yours, some gears and motors lasts longer some not :) and you always flex you chassis during jumps and landing.