For simplicity, the aircraft replaces the gas turbine used on Phase-I with a 120mm EDF (Electric Ducted Fan). An emphasis was placed on minimising the mass of the 3D-printed parts, so a unique lattice structure was designed, using a series of internal ribs placed at 45-degree angles to provide the necessary structural support while allowing the vehicle to be printed without a support structure. This technique allowed us to achieve a thickness of 1.2mm on all walls, reducing the total aircraft mass to 7.6 kg.

Drag the cursor around to see the Phase-I aircraft for yourself…

Selecting a recovery system meant balancing several conflicting requirements. The test range lacks a runway so retractable landing gear was not an option, meanwhile, a net was discarded over; size requirements, concerns surrounding the accuracy required to land on it and the risk of missing. Belly landings are not possible due to the bottom-mounted inlet, which improves engine performance, so a parachute was chosen. This uses a piston-fed ejection charge system to release a 2.4m parachute and lower the vehicle to the ground slowly. This also acts as an insurance policy, should there be a loss of control, with redundant systems providing the required reliability.

The shape of the airframe was the craftsmanship of the aerodynamics team, which analysed several airfoils and bodies to meet our lift and stall speed requirements while minimising drag at Mach 0.7. Constant collaboration with the CFD (Computational Fluid Dynamics) team allowed us to analyse flow conditions and optimise the aero-body in an iterative process, utilising the full capabilities of the CFD package, Star-CCM+, provided by our sponsor, Siemens. As we move to higher speeds in Phase-II the importance of minimising wave-making drag will ever-increase, so the design will be optimised using the area rule. 

(Infographic Coming Soon)

The Phase-I fuselage uses a monocoque design comprised of two main halves separated at the horizontal midplane, along with a fibreglass nose cone and 3D-printed control surfaces. The fuselage halves are made from carbon fibre and heat shaped Divinycell core, with a joggle type connection between them, and a split mould technique is used to create the geometry into the shells. The nose cone is made of fibreglass due to its RF transparency, while the 3D-printed components use carbon fibre infused polycarbonate. The operating temperature of the aircraft can reach up to 85°C, hence the shell is cured in a DIY oven and materials with suitable glass transition temperatures were chosen for 3D printing. The critical load on the aircraft is from the parachute deployment estimated to be around 15g during an abort procedure. This will be transmitted to the aircraft through two bulkheads, chemically bonded to the fuselage shells with the core to provide bending resistance. The Integration and Recovery Team have designed a test plan for ensuring this criterion is met. The avionics mount to an I-beam which is ideal for transferring pitching moments from the canards, while offering accessible space for mounting the avionics. The fuel tank is comprised of fibreglass and kevlar for impact resistance, meanwhile, the inlet is a two-part sub-assembly, allowing the external portion to be 3D printed for easy replacement after a rough landing. Finally, the engine cradle is 3D printed to provide a minimal restriction on the bypass airflow for better cooling while maintaining a robust connection. Prototypes made of PC-CF will be tested to evaluate performance at peak engine temperatures, along with further insulation at the interface.

(Infographic Coming Soon)