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47065

Automobil Sport Issue #10

Ferrari´s Mid-Engined Sports Prototypes by Automobil Sport Code: 47065 Format: Paperback / 160 pages Publication date: 01/11/2016 Availability: Sold Out Price: AU $29.99

Ferrari took longer than their British rivals to recognise the advantages of putting the engine behind the driver. But after their 1961 Formula 1 success with the rear-mounted V6, chief engineer Carlo Chiti set out to introduce the concept in the sportscar sector as well. He did so with the mid-engined 246 SP.

After decades of the great Italian tradition of glorious front-engined racing cars, it was extremely difficult for Enzo Ferrari to accept the necessity to go rear-engined. He was the last of the Formula 1 brigade to make the change in 1960 and ’61. Ferrari did it with V6 engines, compact units that were ideally suited to being placed between the driver and the rear wheels. Traumatic though the change was for the Commendatore, it was ultimately a successful turnabout.

Then it was logical to build sports-racing cars with the same V6 engines in the rear, which Ferrari hastened to do. The first of these was the mid-engined 246 SP sports-prototype, designed under Ferrari chief racing engineer Carlo Chiti. Powering it was the same 2.4-litre V-6 that Ferrari used in its 1960 season Formula 1 cars, slightly detuned for endurance. The first 246 SP was tested at Monza in mid-March of 1961 before its first race, the Sebring 12-hour contest. 

“We thought that the car would turn pretty much the same lap times as the [2½-litre] F1,” Chiti recalled, “losing something on curves because of its extra 120 kilograms, but recovering on the straights thanks to its body design. Instead, we realised that it lost much more on curves than expected and recovered less on the straights despite its speed advantage of 15 to 20 km/h.”

Chiti, test driver Richie Ginther and another engineer present at Monza, the veteran Vittorio Jano, conferred on this peculiar problem. “We felt this was the fault of lift effect,” Chiti continued. “In the past, when I was at Alfa Romeo, I had sensed something of the kind because both Sanesi and Zanardi had seemingly mysterious accidents at Monza on the Ascari Bend.”

Another factor could have been instability caused by the more forward centre of pressure of the fully enclosed body. The 246 SP was equipped with a single small fin to counter this. The car was tested with additional fins, but these offered little help. With its tail completely removed, the 246 SP was slower on the straights, but much faster through Monza’s bends. What was the answer?

Aerodynamic aids

Success, as we know, has many fathers. Chiti, Ginther and Jano all contributed to the solution. “I thought of applying some spoiling devices,” said Chiti, “which in this particular case were pieces of sheet metal in appropriate positions. The improvement, which was enormous, became even greater when the spoiler was placed at the rear.” 

Working as their name suggested, the devices were intended to “spoil” or break up the airflow that seemed to be generating lift over the rear panels of the body. Although perfectly well understood today, this was a revolutionary idea in 1961.

The provisional spoilers made and tested at Monza had the desired effect. After some refinement of its design, the tail spoiler was adopted for the new, more aerodynamic bodies fitted to all sports-racing Ferraris starting in 1961. In fact, the final design was less a “spoiler” than an air dam that reduced lift at the rear of the body and—in spite of its appearance—brought a reduction in drag as well…

More in the current issue!

 

by Karl Ludvigsen

Photographs: Ludvigsen Library, McKlein, LAT, Cahier

Format: Paperback
Pages: 160
Availability: Sold Out
Publisher: AUTOMOBIL SPORT
Publication date: 01/11/2016
Country of publication: AUSTRALIA
Weight: 450 g
Dimensions: 297mm X 210mm
Code: 47065