Wheel Design
BLOODHOUND Design Engine Intake Design Wheel Design Nose Design Base Drag Winglet Design Vehicle Sensitivity Analysis
Aerodynamic design of the wheels took place early in the project and was essentially independent of the design process being followed for the rest of the vehicle. The overall dimensions of the wheel had been fixed at the outset, by structural integrity specifications. The dominant importance of these specifications becomes apparent when it is realised that a 1m diameter wheel will spin at 10,000rpm at a vehicle speed of 1000mph. This results in a massive acceleration of 50,000g at points on the circumference of the wheel. Aerodynamic considerations were applied to design the finer detail of the wheel profile, attempting to take account of the likely interaction between the wheel and the desert surface.
Initially a single-keel and a triple-keel wheel design option were considered. Keels are employed in an attempt to improve the ability of the wheel to generate significant lateral traction with the desert surface. The CFD results showed that the single keel option provided the best performance, in terms of its lift and drag characteristics, while the triple keel option seemed to do a better job of confining the pressure field disturbance locally in the region of contact. Minimising the extent of the disturbance of the desert surface is important, particularly at the front, as this will ensure that the the remainder of the vehicle travels over an undisturbed desert surface.
The data accumulated in this analysis, combined with concerns about the dynamic mechanical response of running with a set of four single-keel wheels, led to the development of a third compromise solution, involving a double keel design. Additional CFD simulations supported the view that this option would offer a compromise between the optimum lift/drag profile of the single-keel wheel and the minimum disturbance characteristic of the triple-keel option, while theoretically being able to deliver a satisfactory dynamic response. Ironically, this design is the closest of all the considered options to the wheels of Thrust SSC, which were adopted without anything like the level of research that has gone into the wheel design for BLOODHOUND SSC.
This CFD analysis was conducted under the assumption that the wheels would be freely rotating, while fully exposed to the airstream. However, it was clear that significant benefits, in terms of aerodynamic behaviour, could be gained by providing fairings for the wide rear wheels. These fairings would also enclose the suspension and wheel brake system. The task of generating potential rear wheel fairing designs began from a blank sheet and three potential solutions were generated. The lift, drag, friction torque and heating of each option was considered and an initial selection has been made, but the design work on wheel fairings continues.