Concept: Creating a multicopter for a gimbaled GH4 below 5 kG AUW
Reading Time: 2 minutesI developed this hexacopter in Y6 configuration at a time when a special permit was required in Germany to fly drones weighing more than 5 kg. Since I wanted more flexibility with regard to my customers’ shooting schedules, I came up with the idea of developing my own system for a Lumix GH4. After doing some basic calculations, I believed I would be able to get it just below the limit of 5 kG. Most commercially available multicopters were either well above this limit or too expensive for someone who could build their own system.
Available products in 2015
DJI S900 – too heavy
DJI, for example, produced the S900 with the Zenmuse gimbal, it had an all-up weight in the range of 6.8 – 8.2 kg. In my opinion, the price for this system was not attractive – at that time, the hexacopter with flight control and camera gimbal alone cost around 3000 €. A remote, the video downlink and the necessary batteries + charger were not included.
Yuneec H920 – too expensive
One product that met the required weight specifications was the Yuneec H920 with the GB603 gimbal for the GH4. Ready to fly it had an AUW of 4990 g. Although it came with all the necessary components for flight operation, it had a recommended retail price of roughly 6000 € in 2015. For this amount of money I could build two camera drones back than.
Design considerations
While pondering the lightest possible construction for the gimbal-carrying copter, I realized that it was important to decide on certain priorities and derive criteria for the basic design from them, which would then lead to clear design decisions:
Criteria:
- A high-efficiency propulsion system is essential to keep the takeoff weight within limits
- The failure of a single motor or esc must not lead to a total loss of the whole system
- A retractable landing gear is required for dual operator mode (pilot/gimbal)
- A flight time of at least 10 minutes is necessary, preferably more
- The copter must be compact or have a foldable design
- Less is more
Derived design decisions:
- High-quality batteries combined with motors and propellers from T-Motor should deliver a good performance
- A Y6 layout instead of a hexacopter layout reduces the frame weight while maintaining redundancy
- A carbon fiber part will accommodate both the gimbal mounts and the retractable landing gear
- Simulations on eCalc.ch show that an average flight time of around 12 minutes can be expected
- Removable propellers and the Y6 layout result in a small footprint
to be finished…
