RE: help attaching props to astroflight firefly motor shaft
The AF Firefly uses a 4:1 gearbox that has a 2mm shaft. There are several places that sell a 2mm prop adaptor.
One example is the MJ4700 Collet Prop Adapter for 2mm shaft for M5 prop holes at [link=http://www.hobby-lobby.com/propadap.htm]Hobby Lobby[/link].
Another place is [link=http://www.bmcproducts.com/]BMC Model Products[/link].
I have adaptors from both places and they keep the prop on perfectly.
The 3x1 U80 prop is too small for proper current draw on the AF Firefly. Use a 5x4 prop like the Gunther plastic "spoon" prop commonly used on Speed 400 Zagi wings. Expect an 800mAh draw at full throttle. I use a 2-cell Kokam 145mAh pack on my setups.
Good luck!