Here's a very nice onboard video of the twin chassis Lotus 88 running at Silverstone that shows how the primary chassis moves in reference to the secondary chassis.
The footage was recorded during an Historic F1 race held at the Silverstone Grand Prix circuit with Katsu Kubota racing his infamous Cosworth DFV-powered Lotus 88.
Rear view footage filmed using Goldstar Onboard Racecam video system that includes the data acquisition numbers.
There are two interesting details to note in the video:
1.We can clearly see how much the tub and the bodywork start moving at different rates. The secondary chassis is softly sprung to give the driver a soft ride. Meanwhile, the primary chassis is stiffly sprung and takes on all the downforce. So the bodywork moves up and down around the driver.
2. Note that the car is going under negative acceleration when Kubota changes gears. This is common to all high-downforce race cars. The car is subjected to positive acceleration (vertical green bar on the left) when the rear wheels are pushing the car forward. However, downforce is so great the car actually decelerates, by as much as 1G, when the driver changes gears because the car is no longer being pushed forward during a fraction of a second (vertical red bar).
The footage was recorded during an Historic F1 race held at the Silverstone Grand Prix circuit with Katsu Kubota racing his infamous Cosworth DFV-powered Lotus 88.
Rear view footage filmed using Goldstar Onboard Racecam video system that includes the data acquisition numbers.
There are two interesting details to note in the video:
1.We can clearly see how much the tub and the bodywork start moving at different rates. The secondary chassis is softly sprung to give the driver a soft ride. Meanwhile, the primary chassis is stiffly sprung and takes on all the downforce. So the bodywork moves up and down around the driver.
2. Note that the car is going under negative acceleration when Kubota changes gears. This is common to all high-downforce race cars. The car is subjected to positive acceleration (vertical green bar on the left) when the rear wheels are pushing the car forward. However, downforce is so great the car actually decelerates, by as much as 1G, when the driver changes gears because the car is no longer being pushed forward during a fraction of a second (vertical red bar).