How F1 cars achieved constant ride height

By Bertie Scott Brown: 

DH (0984cu)LrDave Hamer, the architect of the highly successful hydraulic system now in widespread use on Formula One cars, was one of dozens of racing personalities attracted to this year’s Goodwood Revival.

In 2009 Hamer, a senior R&D engineer at the Renault F1 team, formerly Benetton and now rebadged as Lotus F1, devised a hydraulic system called PPS (Pro Pitch System) that strived to maintain constant ride height. As a consequence it brought much treasured proficiency to the car’s aero systems.

As most racing followers know, ride height particularly front ride height is a critical part of any successful F1 car—they all require a stiff, stable platform. As the car travels faster, the closer it gets to ground level—an effect caused by powerful aerodynamic forces pushing down on the tires.

“Since the banning of active suspension in 1993, explains Hamer, “we had strived to control the car’s ride height without conceding mechanical grip. So for the 1994 season, we tried using some of the car’s damping forces to pump the suspension up, similar to the technology used in Boge dampers. At that time Boge supplied dampers to BMW for use on their touring motorcycles. Their chief objective was to achieve consistent ride height regardless of whether the bike was carrying a passenger or luggage.

“Later we fitted a 10kg tuned mass damper in the nose of the car. This was quickly copied by all the other teams, before being banned. Nonetheless, the tuned damper gave us a decisive advantage, helping us win that year’s F1 Championship with Fernando Alonso.”

Before the introduction of the PPS, front ride heights had been set higher than desirable. But the problem was resolved by placing a hydraulic cylinder at the rear of the car. As the car squats it transfers fluid from the rear suspension to the front, which causes the front suspension to extend and compensate for tire squish. As a result the front ride height remains constant.

“Although Fernando Alonso tested it before the 2009 season started and declared he liked it,” said Hamer, “it couldn’t be modeled easily and therefore wasn’t used until later in the year, at Nurburgring in fact. Then Bob Bell, our Technical Director at the time, knowing I’d been testing it on a 7-post rig for a year, took the initiative and had it installed.”

Predictably, its admirable qualities were quickly realized. But in 2010, the Renault F1 team lost their star driver, Alonso, to Ferrari and the Italian team acquired the new system as did virtually every other team in the paddock!

Hamer, a warm congenial man, is typically unassuming about the significance of the Pro Pitch System. “It was based upon something I remembered from my youth. In the mid-1960s Dr. Alex Moulton pioneered Hydrolastic suspension for the Mini and other small BMC cars. He, too, had been seeking a system that would remain level and resist pitch. So I really didn’t invent it I just borrowed it for a different application. What surprised me, though, was by juggling with it in *heave and pitch stiffness, I succeeded in recovering the entire mechanical grip I’d lost in the stiffening process. So I suppose we got something for nothing.”

* In F1 jargon the vehicle is considered as having 6 degrees of freedom; that is, 6 axes in which the car can move. They comprise 3 translational movements and 3 rotational movements. The translational movements are vertical (heave), lateral (sideways) and fore and aft (forward/backward). The rotational movements are known as roll, pitch, and yaw. Heave is defined as amount of up and down body movement—the same amount front and rear.

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