Traditional Helicopter — Connecting and Calibrating the System

The Cube Info

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The Cube is highly recommended for helicopters. It has much better internal damping of the IMU’s for vibration, triple redundant heated IMU’s, redundant barometers and compasses. Experience has shown the tuning, handling and stability performance of your helicopter will be greatly improved over the first generation Pixhawk.

Before you begin connecting the system it is recommended to review the docs for The Cube available here

Overview of servo, and RX connection

The RC input to The Cube is either PPM SUM, which will give you 8 channels. Or S.Bus, which will give you up to 18 channels. If you have a receiver that outputs only PWM, you will need a PPM encoder to connect it to The Cube.

The default RC input and SERVO output mapping is as follows:

RC Channel SERVO output
1 Aileron
2 Elevator
3 Collective
4 Rudder
5 Flight Modes
6 Tuning
7 Aux
8 Throttle

The output pins on The Cube for SERVO’s 1 thru 8 are labled Main Out:

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Motor 1, which is normally the left front servo on your helicopter goes to pin 1 on The Cube. Motor 2, which is normally the right front servo goes to pin 2. Motor 3, which is normally the rear (elevator) servo goes to pin 3. Tail servo goes to pin 4.

If you are using a DDVP (Direct Drive Variable Pitch) tail rotor, the tail motor ESC connects to pin 7. The throttle servo or ESC for the main rotor motor connects to pin 8.

You must supply power to the servo rail to power your servos at their appropriate rated voltage. The Cube does not supply power to the servo rail.

Connect telemetry radios, GPS/compass module, power to The Cube itself, and any other peripherals as per the instructions in the owners manual for the unit.

RC Calibration

Warning

Before powering The Cube and servo rail, on all helicopters disconnect the rudder linkage from the tail servo or bellcrank on the tail gearbox. If you have a piston engine helicopter, also disconnect the throttle servo linkage.

The RC MUST be calibrated before proceeding once The Cube is powered up. RC calibration is identical to all other vehicles. With helicopters using the ArduPilot system there can be no mixes in the RC radio. All the outputs must be “pure”, i.e. use either airplane mode in your radio, or helicopter mode with H1 or “straight” swash. See this topic.

Compass Calibration

It is recommended to calibrate the compasses at this time as well. This is the same as all other vehicles. See this topic.

Accelerometer Calibration

If the accelerometers were not calibrated on the bench prior to installation it must be calibrated before proceeding. See this topic.