Peter Brock on the birth of the spoiler

Story by Peter Brock • Photograph Courtesy the Author



It seems difficult to understand why people are still so interested in the origins and concept of a 50-year-old racing car, but fascination in the aerodynamic details of my design for the Daytona Cobra Coupe continues unabated. There are books on the subject where I explain how its unique shape was derived from an obscure pre-WWII paper written by some very bright Germans.

But what’s most ironic is that the car’s most advanced component, a driver-controlled wing for downforce, was never utilized. The inspiration for that rear wing came long after that paper was published.

In 1963, my good friend Richie Ginther returned briefly from Italy and related a discovery he’d been involved with that changed racing forever.

He’d been hired on as a test driver for Ferrari, and his goal was to eventually drive in Formula 1, following in the footsteps of his friend Dan Gurney. One of Ginther’s first responsibilities was to develop a new mid-engined sports racer that was being prepped for Le Mans.

Testing took place on the tiny local circuit within walking distance of the center of Modena. Locals would often come out to watch when they heard the distinctive V12s fire up.

In France, the Auto Club d’Ouest officials in charge of establishing special rules for the famed circuit were more than slightly concerned about the ever-increasing speeds being reached on the 3.7-mile ligne droite des Hunaudières, a two-lane country highway better known to us Americans as the Mulsanne Straight. A horrendous crash on the circuit’s front straight in 1955 had almost turned world opinion against all racing, so the ACO’s main focus was on somehow reducing top speeds to increase spectator safety.

One strategy was to disallow the low racing windscreens of previous years. A new rule mandated an increase in frontal area, requiring high windscreens like those used on production cars in an attempt to increase drag and reduce velocity.

In testing, the Ferrari’s new windscreen reduced speed as expected, but it was also causing Ginther some discomfort behind the wheel. Air flowing over the higher screen created a low-pressure area in the cockpit, which tended to suck exhaust fumes from the rear of the car back into the driver’s area.

Ginther had been a helicopter mechanic in Vietnam, so he had some understanding of basic aerodynamics. To counter the reverse flow of fumes, he suggested that his mechanics fashion a small, 4-inch-high aluminum “fence” across the rear of his car. This was done in a matter of minutes, and Ginther again ventured out to see if the problem had been solved.

It had, but the added “fence” also had an unexpected result: It allowed him to lap almost 2 seconds quicker!

At the time, no one realized the significance of attaching this simple strip of aluminum. But it actually marked the beginning use of downforce as opposed to just minimizing aero drag, which had been the goal of designers since the discovery of wind resistance.

The addition of this rear “spoiler” was at first simply a curiosity questioned by the French officials and members of other teams. Ferrari mechanics answered their inquiries with casual off-hand comments that it was merely a device to prevent exhaust fumes from getting drawn back into the cockpit.

Speed secrets don’t last long in racing. Others suffering flow reversals from the higher windscreens soon copied Ginther’s exhaust fume spoiler and discovered the additional speed, traction and stability gained by attaching the simple device.

Naturally, this additional rear downforce created a reactive loss of traction at the front, so it wasn’t long before Ginther had fashioned a compensating front air dam to regain lost steering sensitivity.

Not surprisingly, adding front and rear spoilers soon became a simple, generally accepted way to balance a race car’s adhesion at speed. So the ACO’s original intention to limit speed was negated by chance—and by Ginther’s clever innovation!

 

IBINTHERBEFOR New Reader
3/26/22 11:35 a.m.Aero drag is usually considered as consisting of three elements; lift, shape and surface with frontal area a big deal multiplier. The spoiler destroys lift drag at the expense of a minor increase to shape drag. Peter's original concept of a ring spoiler would have done the same thing BUT the shape drag would not have been increase as much, and the device was tunable for different tracks. Because the device was movable it could be used to radically increase shape drag to aid braking and then repositioned for

straight speed. The use of down force devices actuall increases shape drag to the point that top speed is reduced but cornering capability is radically increased, thereby reducing lap times. Look at or read the history of the Chaparrel. A couple of more things, the Daytona had a small forntal area, Look at pics of it along side the Cobra roadster. Lastly there's the whole subject of internal aiflow and the flow of air under the car.

There's a good SAE paper on how Ford used under car airflow on the 2005 GT. Another interesting place to look is at Gordom Murry's T50 "fan" aided aero car for the street.