Over the last few months as I have described the history of vehicle manufacturing you will have noticed the close relationship between cars and aircraft – primarily because both industries were born around the same time and used similar components or materials. It was common for aircraft component manufacturers to re-use the technology for automotive use.
Ground Effect was one of these concepts that crossed over. In an aircraft, Ground Effect and aerodynamics are used to keep the aircraft up in the air and to provide reduced drag on the wings when they are close to a fixed surface. This is a very complex science (physics I would suggest) that cannot be described in a simple blog!
For a vehicle it is the opposite, it pushes the car down on the ground causing better grip with the outcome of faster cornering. Downforce on it’s own though is not Ground Effect – it is a combination of the vehicle and the ground on which it travels. The theory is that the smaller the gap between the vehicle and the ground will reduce the pressure underneath and increase the pressure above thus causing the vehicle to be pushed downwards on to the road causing higher grip. This grip is also dependant on the tyres doing their job properly!
So, it’s not surprising that these concepts were adopted by the motor sport manufacturers to get a competitive edge. The Chaparral car of the 1960s was the first to sprout wings and other devices although they were quite flimsy and there were several major accidents as the structures failed under pressure. The concept wasn’t well understood and the sport ultimately banned moveable devices on cars. Jim Hall who owned Chaparral used wings that moved up and down to adjust the downforce as the speed increased. It was important to keep the downforce equal at the front and back, so that grip was not compromised at either end.
Formula 1 in the late 60s saw a similar issue with flimsy wings as the materials used weren’t strong enough to provide the desired effect – carbon fibre and Kevlar were not available for use at this time. So the designers started to look firstly at smoothing out the flow of air over and around the car by using wider side pods between the wheels and strategic but lower mounted wings to push the air away from the front.
By 1977, Lotus and Brabham were trying different ideas and it was Lotus that came out on top. The Brabham-Alfa BT46B used a large fan with skirts on the underside of the side pods that extracted the air from under the car. This car raced just three times before being dropped by Brabham’s owner Bernie Ecclestone. It did win the Swedish GP and showed that the concept provided masses amount of grip, so much so it was rumoured that when the car was idling it was sucked down on to the ground!
Lotus however used the side pods with radiators in them, skirts and a flat underside. The Lotus 78 & 79 cars also had the pods styled to give better aerodynamics. Theses cars were championship winning designs and pushed the boundaries of the rules.
One side effect was that if the “Ground Effect” was lost momentarily, the huge amount of grip was lost and the car would lose all steering control thus causing a bigger accident and the flat bottoms acted as a sail if the car managed to lift the front wheels too high. Remember the Mercedes Le Mans cars flipping at high speeds down the Mulsanne Straight?
The Ground Effect designs in F1 also changed as more works teams with big budgets used specialist testing equipment to add venturi tunnels and winglets to improve the stability of the cars as they changed direction. This saw some dramatic changes in single seater design that spread throughout the different categories.
The work done by these teams can now be seen in road car designs where the designers use ideas first tested in F1 and Group C sports car racing to improve the aerodynamics and thus create a faster vehicle and/or reduced fuel consumption. The Bristol Fighter is a good example of this where the car actually increases power when driven faster and still has excellent fuel economy.
So we have discussed aircraft and land-craft, how about sea-craft using Ground Effect? Surely that’s not possible as the water is not flat?
Well several companies over the years have tried to make Ground Effect craft for water – surely Water Effect you say! In the 1990s Boeing developed a prototype called the Pelican Ultra Large Transport Aircaft and over in Russia (or Soviet Union as it was then) there was a prototype called the Ekranoplan. Two German engineers even tried to make an aquatic sports car – I’m sure that Colin Chapman at Lotus would have done this had he lived longer – he did design a super-yacht!
Well a new prototype has been seen – a South Korean corporation called Wing Ship Technology Corp has developed a craft with a delta wing (similar to Concorde and the fabulous Vulcan aircraft) and powered by two turboprop engines inside a catamaran hull. The difference between Concorde and this craft is that the wing is upside down – or a reverse delta. Top speed has been quoted as 180kph (110mph) and it can carry 50 people. One of the advisors just happens to be one of the German engineers of the aquatic sports car, sharing his experience.
The craft uses the engines to create a small amount of lift like a hovercraft until it can gain enough speed to “float” on its own at 5 metres above water. If this works and is put into production it will become a very fuel efficient form of transportation as it can use less fuel than an aircraft but travel faster than a ship because there is less drag from the water.
So Ground Effect craft are still being developed for newer forms of transportation and may well be seen in regular use in the near future. This is what I like about engineering, there is always a better way to do things!