Flying low
Is it a high-speed car? Or is it a very low flying aeroplane? When considering the stability and control of very high velocity cars, the answer is: neither. These vehicles have unique characteristics and their stability must be analysed from first principles.
Much has changed since the early jet cars of the 1960s. Access to computational fluid dynamics (CFD), CAD systems and low-cost instrumentation has transformed the field of Land Speed Record (LSR) attempts, and it is now feasible to design record cars that will exceed the velocity of sound.
The dynamic yaw response of Bloodhound will probably feel like that of a supersonic hovercraft or hydrofoil, if such things existed
This piece is a summary of lessons learned from Thrust SSC and the JCB Dieselmax, which are being employed in the design of Bloodhound, the project that aims to break the 1000mph barrier and is due to undergo high speed testing at Hakseen Pan, South Africa, this autumn, where 500mph is being targeted. The project has been relaunched recently after being saved by businessman Ian Warhurst.
Dieselmax is included here because at its top speed of 350mph the flow around the wheel-to-ground contact points locally exceeded the velocity of sound. Thus, Dieselmax genuinely qualifies as ‘transonic’, since this is actually defined as ‘locally experiencing both subsonic and supersonic flows’.
We’ll start this examination by looking at wheel loads. As a vehicle running by itself on a smooth surface without obstacles, there is only one object with which the LSR car can have a collision, and that is the track surface – there is nothing else to crash into. Therefore, to avoid such a collision, the primary safety of the vehicle comes down to keeping all of the wheels on the ground, all of the
