A while back I described the use of the monocoque to produce a very strong but heavy chassis that probably 90% of the world’s mass produced cars use. As a follow on, I’ll talk about the space frame chassis that really took off after World War 2, however like many technologies had it’s birth closer to the start of the industry.
A space frame is a truss – multi interconnecting tubes that provide strength and support for multi directional forces. Many early cars used a ladder chassis that was strong but could flex when forces were applied from the side for example. They were good at handling acceleration and deceleration but when a sideways force was applied in cornering, the chassis would twist slightly even with a body bolted on. The space frame removed much of the ability of the chassis to flex when subjected to different forces.
The original concept was defined by Alexander Graham Bell, the inventor of the telephone, around 1900, when he was researching new forms of aircraft – he was actually one of the pioneers of powered flight! The idea was to make the structure as strong as possible but light so that the plane could leave the ground. One of his partners in this venture was Glenn Curtiss, who not only became a leading visionary for aircraft but was also to become a big name in motorcycling where the space frame became a common chassis. Incidentally the Curtiss company was associated for a while with Studebaker and is still in existence making parts for different types of machines.
The architect Buckminster Fuller took the concept and used it to support his buildings and even designed a car, the Dymaxion, in the 1930s – the cross over from aeronautics was in full swing by this time. During the 1940s, the idea spread to Europe with Cisitalia developing the D46 racing cars with a chassis made of tubes.
However, it was another 10 years before European designers really started to use the same concepts – clearly if you can build an aircraft which is light and very strong, a car designed using the same ideas would be equally efficient. One of the first cars was the W194 Mercedes 300SL racing coupe in 1952 that evolved into the classic W198 300SL Gullwing road car (thanks to Max Hoffman). The tubular space frame design prompted the gullwing doors due to the side tubes being relatively high and the lightweight frame was then strong enough to give its underpowered engine a chance against more powerful but heavier cars – a chance it grabbed by winning many major sports car races.
Interestingly, Jaguar also used a tube frame on the C-Type that was in direct competition to the Mercedes-Benz: winning the Le Mans in 1951 and 1953 with the Mercedes taking the 1952 race. At that time, Colin Chapman at Lotus started selling the Mk6 for racing and this used a very light tubular frame for the same reason. Most of the subsequent road and race Lotus models used the space frame concept. Chapman had studied aeronautics at university and had applied aircraft concepts to cars from the late 1940s.
Maserati too had a series of racers called the Birdcage – the Tipo 60 through to the Tipo 65 were Le Mans racers that took their nickname from the chassis design. They weren’t as successful though as the Mercedes W194.
Most single seater racers soon adopted this chassis as Lotus started to dominate Formula 3, then Formula 2 and finally brought the rear mounted space frame racer to Formula 1 along with Cooper. In fact it was Lotus that caused the Indy racers to switch from front engined sprint cars to the now established rear mounted design.
Over the years this design has been seen underpinning many cars including the Ford GT, the Pontiac Fiero, many Ferraris and even the Porsche 550 Spyder that James Dean ended his short career in. Today, manufacturers such as Lamborghini still use the space frame to provide a strong light frame for their cars and Lamborghini’s stable mate Audi have developed an all-aluminium space frame for their A8 saloon. Since 1993, the A8 has had a space frame chassis and they go further by bonding the panels to the frame so that they also share the load. The TT and R8 models also have some of this design and Audi won the European Inventor of the Year award back in 2007 for their chassis despite the fact that the design was 15 years old!
If you buy a low volume specialised sports car like an Ariel or IFR, you will be using a space frame to help keep you on the road. It is a very efficient design and I’m sure as cars need to get lighter, more manufacturers will return to using this type of chassis.