The TBS GEMINI
On the GEMINI hexacopter, the motors are tilted 10° forward in order to decrease the angle of attack of the
body in forward flight. The whole arm is deformed in order to achieve the desired forward tilt. This
decreases the net aerodynamic drag in fast translational flight. In a hover the body will lean backwards but it
will level out as it moves into forward flight. Additionally, the canopies help to reduce the drag coefficient of
the copter. The effects has been measured in a wind tunnel using a two-axes force balance, and the results
show that the drag is reduced by something around 30%.
The handling of the copter is not affected as long as the IMU is aligned parallel to the propellers (you can also
rotate the IMU by software via calibration).
The flight controller is based on the TauLabs Quanton platform and TBS contributes back to the project. The
controller has two modes. In "stabilize" mode (angle control) is auto levels and stabilized itself in flight, while
in "heading hold" (angular velocity control) it will stay in a particular angle until the pilot makes corrections,
very much like “manual” mode. There are a lot of other interesting features.
The TBS GEMINI has a two part canopy with a larger volume. This allows for using large batteries, a broader
range of video transmitters and larger receivers (hence people can install the gear they want). We selected to
include some very nice and light custom T-motors, these are made to precision with high quality bearings.
The ESCs were also developed specially for the GEMINI. They are located centrally on the frame in a stacked
rib formation for cooling and easy access. There are no LEDs on the canopy as of writing, but LEDs can easily
be added to facilitate LOS flight.
Maybe one of the most important factors is the 3S to 4S capability. The ESCs are able to handle both with
ease to cater for long fight time or high speed. When using the custom TBS ESCs on 4S, expect an
exceptionally fast forward flight and a rocket in ascend.
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