Members of the BLOODHOUND supersonic car project and Renishaw have collaborated to produce a prototype for a critical component of the Supersonic Car. BLOODHOUND’s aim is not only to break the sound barrier but also to be the first land vehicle to exceed 1 000 miles per hour (1609 km/hr) — at this speed it will be travelling the length of 4.5 football fields every second.
The majority of the cockpit and nose is made from carbon fiber reinforced epoxy. During the record attempt the car will experience more than 20 000 kg of skin drag. However as the nose tip is on the ‘leading edge’ it will experience a greater proportion of this load, up to 12 000 kg/m².
“We believe that the key benefit of using an additive manufacturing process to produce the nose tip is to create a hollow tip to minimize weight. To machine this component conventionally would be extremely challenging, result in design compromises, and waste as much as 95% of the expensive raw material,” said Dan Johns, BLOODHOUND SSC.
Renishaw engineers and Bloodhound designers modeled weight-reducing features in the nose tip. The resultant prototypes were printed on Renishaw’s laser melting additive manufacturing system.
Although the outer surfaces of the nose tip polyhedron appear flat, there are in fact subtle curves, which contribute to the aerodynamics. The Renishaw additive manufacturing (AM) machine makes the part to an accuracy of ± 50 μm over the 250 mm bed so it is able to accurately reproduce the geometry of the CAD model.
The hexagonal honeycomb of the nose tip is an intrinsically strong design. But the honeycomb internal structure is more complex than a uniform wall and uses less material so is cheaper to manufacture. To manufacture it on internal surfaces would be very difficult using traditional machining technology. The hollow pocket depth is 130 mm, and tapers. To be machined the nose tip would require a thicker cutter to maintain stiffness, and this would affect the shape that can be made. With additive manufacturing there is much more scope to manufacture novel shapes with ease.
Currently, physical manufacturing capabilities outstrip digital design capabilities. But software is rapidly improving to capitalize on the design potential.
Part of the benefit of AM is how it reduces the development and prototyping cycle from months to days, freeing engineers and allowing prototypes to be made without part-specific investment. The prototype can be tested and refined to establish further improvements.