Racing cars on walls possible: study

Driving a racing car at an angle of 90 degrees to the ground could be possible with the right track design, according to a new research.
While many stunt racing enthusiasts must have wondered whether it would be possible to drive their car along vertical walls, University of Leicester physics students have found that it is indeed a possibility.
However, it would only work with a very specific racing track and a very well-designed car so it is "unlikely to ever become a reality."
A group of four researchers have worked out that a racing car travelling at over 241 km per hour would be able to stick to the walls of a completely circular speedway track with 90 degree banks.

This would happen because at those speeds, the force of gravity acting on a racing car would be less than the frictional force holding the car on the wall.
The researchers decided to investigate this because it has been previously shown that speedway cars actually travel at their fastest around the steep bends of speedway tracks.

The group chose to look at two different vehicles - an open wheeled Penske-Reynard-Honda racing car and an Audi TT road car - to compare how different car shapes and characteristics would affect their gravity-defying capabilities.
They then analysed the forces acting on each car if it was travelling around a completely circular speedway track at 90 degrees.

It is important for the track to be circular, so as ensure a constant centripetal force - the inward force of an object travelling in a circular path.
To work out whether the force of gravity on the car was less than or equal to the static friction force holding it on the wall, they needed to include a range of factors including the mass of the vehicle, the car's speed and its centripetal force.
Another key factor was the downforce - the force sucking the car into the wall on due to its aerodynamic properties. This was obviously a lot greater for the sleek, efficient sports car than the comparatively everyday-looking Audi.

They found that for an open wheeled racing car weighing around 700 kg, the force of gravity would be 8571N less than the frictional force, meaning the car would easily be able to stay on the vertical banking.
But for the 1,390 kg Audi, the force of gravity was around 6400N larger than the frictional force, meaning the car would tumble off the wall - presumably with grim consequences for both car and driver.
The researchers pointed out that vertical racing is unlikely to ever become a reality as "such a track would likely be both hugely expensive and very dangerous in the event of a crash."

The researchers published their findings in a final year paper for the Journal of Physics Special Topics, a peer-reviewed student journal run by the University's Department of Physics and Astronomy.