The Team Behind Redback

Key design decisions

• Carbon-fibre airframe

  Redback's endurance requirements demanded an airframe that was both lightweight and structurally strong. Carbon fibre was selected because of its strength-to-weight performance and the team's extensive experience manufacturing composite structures.

• 3D-printed mounting components

  The comparatively low loading placed on many mounting components made additive manufacturing a practical option. It supports rapid design iteration while allowing replacement parts to be manufactured quickly during maintenance and repair.

Key design decisions

• Receding-horizon motion planning

  DNA adopted a classical, first-principles approach to generating dynamically feasible trajectories in real time. Receding-horizon planning predicts the aircraft's future motion and selects the immediate action that best supports safe obstacle avoidance.

• Companion-computer control

  The system asserts control through a companion computer while the aircraft operates in guided mode, allowing position, velocity and acceleration setpoints to be issued. Control can be revoked immediately through a flight-mode switch, preserving a direct safety override.

Key design decisions

• Overhauled telemetry pipeline

  Redback was transitioned to the Herelink telemetry system to provide a reliable, high-bandwidth connection between the aircraft and ground operators. The previous system struggled when MAVLink data, video and control traffic shared the same connection, making a more robust telemetry pipeline necessary.

• Increased mission speed

  Although 7 m/s was identified as the most energy-efficient cruise speed, flight testing showed that increasing the endurance-phase speed to 17 m/s reduced the mission's overall battery cost by significantly shortening its duration. This also provides greater competition flexibility by allowing additional endurance laps or a repeated search phase.

Key design decisions

• Passive braking

  The Lifeline system uses the kinetic energy generated during the payload's descent to regulate its speed rather than relying on an external power supply. This reduces demand on the aircraft's battery and supports greater mission endurance.

• Fail-safe release actuation

  A servo-driven mechanical release provides a simple and reliable PWM control path from the flight controller. The mechanism is designed so that the payload remains secured if logic power is lost.

Testing process

The team bench-tests the control system and release mechanism as part of its pre-flight safety checks. Payload releases are then tested from the aircraft during flight to replicate mission conditions, while digital simulation supports the selection of components that control descent speed and delivery time.

Key design decisions

• PyQt6 desktop application

  The team considered both web and desktop architectures. Because the system requires only one active client, a desktop application was selected and built with PyQt6, using technologies already familiar to the team and suited to rapid development.

• Communication broker

  An MQTT broker was selected to coordinate communication between Mission Management, DNA and Vision because it is widely used for connected systems and has extensive documentation. Protocol Buffers are used when communicating with DNA's Raspberry Pi, while Vision currently exchanges JSON messages.

Key design decisions

• Quad-rotor motor configuration

  A quad-rotor configuration with one motor per boom was selected instead of a coaxial arrangement. This reduces power consumption and supports the competition endurance requirement, while retaining the proven reliability of a conventional quad-rotor layout.

• Custom propellers

  The efficiency limitations of readily available propellers created concerns around achievable flight time. Custom propulsion components were therefore selected to improve energy efficiency and address Redback's endurance requirements.

Key design decisions

• BEC power harness

  The power harness distributes regulated power from the main battery to systems including the flight controller, communications hardware and sensors. It protects sensitive electronics from voltage instability and allows each subsystem to receive reliable power without requiring separate batteries.

• Efficient routing and placement of components

  Stratigically mapped the placement of electrical compoenets and routed the wiring harness to minimize cable length, reduce electromagnetic interferance, and improve power efficiency. The layout optimises cooling, and makes the electrical system easier to inspect, maintain and troubleshoot.