EV Chassis

Chuck a car out of the back of a Hercules and gravity will accelerate it to 60mph in under 3 seconds. Back on the ground it is no coincidence that a few supercars also accelerate this fast. They have enough power to give a push on the ground equal to their own weight; a similar scenario to the car falling out of the sky. Friction limitations of normal road tyres level the playing field for all these powerful cars but in the next 5 years there will be cheaper sports cars and hatchbacks that can perform better, and they will be electric. The 2016 Pikes Peak race was won convincingly by an electric car powered by six Yasa electric motors. Four of the motors used in the racer will do fine for an example of how our future car should perform. Allocating one to each wheel of a 3,000lb car means that it has to transmit 750lbs of shove on the road to push 750lbs weight to match the supercars. With a reduction gear of 2.8 the Yasa 400 motor has enough torque to do this and yet still not run out of revs before 190mph. For brief periods the maximum combined power of the motors is 880bhp so that should be erm, adequate if twice the power of a Porsche Turbo can be called adequate. In practice the acceleration should be better than anything on the road today because with each wheel finely controlled to prevent wheelspin the grip will be as good as it gets.
Individual wheel control will also transform road holding and handling. Imagine cornering with the outside wheels getting extra power and revs to augment the steering; worries about oversteer and understeer will be things of the past. In the same way that your satnav spookily shows the road ahead the on board computer can calculate the best power allocation to all the wheels to enable a safe trajectory through the bends and at speeds not really experienced in any car yet.

Pretty exciting stuff, but there’s more to come.

Of course if we could add enough downforce to effectively double the weight of the car (but not the mass) then it could go twice as well. 0-60 in 3 seconds becomes 0-120 in 3 seconds and back to a stop a neck wrenching 3 seconds after that. Cornering speed would depend more on courage and neck muscles than mechanical limitations. Sounds like fantasy land but actually it would be pretty easy to do this. Under the car a fan powered sucker pad, like an inside out hovercraft skirt, can easily develop sufficient downforce. The pad doesn’t actually touch the ground as small rubber wheels keep it a few thou clear. Obviously one wouldn’t drive around with the pad deployed all the time. It would be for track days or for seeing off the odd supercar at the lights.

Time for some maths.

A 60″ diameter pad has 2,827 square inches.  If the inside was a perfect vacuum the pad would hug the ground with over 18 tons (atmospheric pressure 14.7 psi). There would be heaps of torn up tarmac behind the car along with the odd flicked up manhole cover. Fortunately we just need a vacuum of a smidge over 1 psi to equal the weight of the car.  As I say – easy.

Regenerative electric braking relieves the mechanical brakes somewhat so with reduced cooling requirements the discs and calipers can be mounted inboard on the motor plates which in turn can also double as suspension mounts. The reduced unsprung weight will give superlative handling.

These power and suspension units can be deployed over a wide range of vehicles so, as I said, there is nothing particularly expensive here, in fact, quite the reverse. Anyone about to buy a £2m hypercar might like to pause for thought; the new era regular sports cars will soon leave it for dust.

For a more technical look at the suction pad look here

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