Building a 1/2 Scale Prototype


The idea is to build a 1:2 scale prototype before starting with the real thing to gain some experience with the flight controller, the Ardupilot software and all the required technology. Since the real FlyRider will become 2 meters wide and 2 meters long, the prototype will become 1 by 1 meter. The frame is built from 15 mm aluminum square tubes.


Motors for the prototype are EMAX MT-2216, according to the supplier they shall provide 0,95 kg of thrust with a 10 x 4.5 prop at 14,8 V (4S) and 14.6 A. The real FlyRider aircraft is planned to have a 1,5 / 1 thrust to weight ratio. With a total peak thrust of 5,7 kg the weight limit for the prototype is 3,8 kg to achieve the same thrust to weight ratio.

Speed Controller (ESC)

As motor speed controller (or ESC = Electronic Speed Controller) I use a Hobbywing X-Rotor 20A ESC. Since the EMAX MT 2216 consumes 14.6A at full power, a 20 Amp ESC should be sufficient, especially since no long duration flights are planned with the prototype.


As batteries I need a set of 4S Lipos (14.8 V) which can at least provide 45 A to be able to use one Lipo for 3 motors. A 5000 mA battery is able to provide 45 A for more than 6 minutes, enough time for the planned test flights. Make sure that the batteries have the C rating to be able to provide the current needed to get full thrust out of the engines. The C rating, quite simply, refers to the capacity of energy the battery can safely discharge, represented as a multiple of its overall capacity. Thus a 5000 mAh 20 C battery should be able to provide 100 Amp peak current (5A * 20C = 100A) - at least in theory. It is best to have a discharge rate overhead of 30%. For a 5000 mAh 20C battery a discharge with 45 Amps should be no problem.

Pixhawk Flight Controller

Initially “Pixhawk” was a student project at ETH Zurich. Little did the team know that it would end up having such a large influence on the drone industry. Today pixhawk is one of the leading flight controllers for UAVs and drones.

Some technical data:
    32 Bit Arm Cortex, 216MHz, 2MB memory, 512KB RAM
On-board sensors:
    L3GD20 3-axis 16-bit digital gyroscope
    LSM303D 14/3 Axis Accelerometer Magnetometer
    MPU6000 6-axis accelerometer / magnetometer
    MS5611 high precision barometer

    8-16 PWM outputs (8 from IO, 8 from FMU)
    5 general purpose serial ports
    3 I2C ports
    4 SPI buses
    Up to 2 CANBuses for dual CAN with serial ESC


Pixhawk is a sophisticated flight controller, but only the hardware. Without suitable software it just can't work! Fortunately, there is a variety of software that can run on Pixhawk, my choice is "ArduPilot". ArduPilot is one of the most advanced and reliable open source autopilot software available, it has been under development since 2010. The software is capable of controlling almost any vehicle system imaginable, from conventional airplanes, multi-copters and helicopters to rovers, boats and even submarines.

Parts Required for Prototype

6 x EMAX MT 2216 motor (or similar)
6 x Hobbywing X-Rotor 20A ESC (or similar)
2 x 5000 mAh LIPO with min. 20 C  (or similar)
1 x Pixhawk Flight Controller

Calculation of estimated Weight

1 x frame alu 15x15x2 mm with fittings  1.5
6 x EMAX MT 2216 motor with prop        0.6
2 x 5000 mAh LIPO                       0.8
6 x ESC 20A +  1 x flight controller    0.2
1 x flight controller battery + BEC     0.2
Total in kg                             3.3

Weight limit                            3.8
Margin                                  0.5

Prototype hardware is complete and ready for flight...