Sub Micro (Spy) Blimp Building with Hacked Servos

Step 6 Flying and Fitting a tail Fin

When test flying, a tail fin proved to be very valuable to make flying straight forward reasonably easy. First the up/down propeller al be it tiny, gives some spin to the balloon. Second, the tail rotor is clearly overpowered. A fin keeps the blimp on its straight path and the extra power still allows for short turning when desired.

The tail fin is made out of Depron and attached with some tape. I made it hanging down so it helps protecting the propellers from hitting floors or walls. Also it keeps the blimp some distance from any landing surface. This proved to be important as the middle propeller looses efficiency when pushing close to a surface, making lift-off difficult. So no hovercraft effect there.

Obviously the weight trimming needed to be corrected for the fin.

With a tail fin flying the blimp is not difficult, but full control will take some practice.

Moving forward does need to be compensated with more upwards propulsion. The front propeller speeds up the air under the balloon creating an upside down wing effect.

I usually start by giving up till the blimp keeps about the same height and then give it just a little more and start moving forward, adjusting the speed to keeping  more or less the same height.