For the first running of the 24 Hours in 1923, it was mandatory for cars to complete at least five laps with a windscreen erected. It was then left up to competitors to leave their windscreen raised or lowered. As luck would have it, rain and even hail damaged a part of the track that year, freeing pepples from the underlay, resulting in the systematic destruction of headlights, windscreens and radiators. Lesson learned at Chenard & Walcker who substituted a simple wire mesh for the windscreen of its famous "tank" in 1925.

Many windscreens were then split horizontally with the bottom part remaining fixed and the upper part lowered or removed entirely. But these half windshields increasingly failed to protect drivers who opted for their own individual “windscreens” in the form of aviator-style glasses

Gradually, the half-windscreens evolved into ones aimed solely at protecting the driver. Naturally, glasses remained essential to protect against some of the wind due to speed, as well as rain, oil and rubber splashes, and the fragile nature of those small glass plates.

At the 1938 24 Hours, Alfa Romeo long held the lead with a closed body car, the 8C 2900B coupé, which that same year had won the transalpine Mille Miglia road marathon thanks to Clemente Biondetti. He shared the car at Le Mans with French two-time 24 Hours winner Raymond Sommer who clocked the fastest in-race lap before being forced to retire. The car's windscreen had been inserted into a joint to fix it to the bodywork, but the cars of that era were not very sturdy and the simple glass windscreen was still just as fragile. It was then cut in half vertically to resist the stress more effectively.

Shockingly, during the night at the 1950 24 Hours, a crow shattered the windscreen of future winner Louis Rosier's Talbot T26GS. Research into aerodynamics was in its infancy, but it was nonetheless understood the less a car resisted air penetration, the more performance improved. Open bodies became preferred by manufacturers, causing less wind resistance with a small windscreen in front of the driver. In fact, other than Mercedes' win in 1952 with a coupé, only open cars triumphed in the 1950s.

Beginning in 1956, the ACO ensured driver safety by requiring manufacturers design their cars with a cockpit 120 cm wide and a windscreen 100 cm wide and at least 20 cm high.

An Italian revolution

In 1961, Saint-Gobain Italia began installing triplex parts in the factory Ferrari 150 TRI, at the location of the driver and windscreen wiper, embedded in a wide aerodynamic Plexiglas windscreen. Triplex, made up of three layers of glass enclosing two sheets of transparent plastic, became standard in windscreens in the following years. If gravel made contact with the first layer of glass, it did not shatter the second or third layer, providing improved safety for drivers.

Regulations once again increased the height of windscreens in 1963, causing hesitation in choosing a closed or open body car. The Ferrari 250 and 275 P remained open, and their rivals, the Ford GT40s, were closed. Leading up to the 1967 24 Hours, the windscreens on the GT40s were known to crack, so Ford shipped by special plane from Dearborn (U.S.) to the Arnage airport five spare windshields in first class seats.

The evolution of triplex glass techniques has rounded the shape of windscreens and gradually made them more aerodynamic. The curved windscreen trend started in 1966 (Ferrari 330 P3, Chaparral and Porsche Carrera 6) and continued until 1971 (Porsche 908 and 917, Ferrari 512 M).

In 1972, with the reduction in engine capacity to 3 litres, small and lightweight cars made a comeback, outfitted with a simple windscreen. The aerodynamics were not yet up to par, so the Renault-Alpine A442 B, winner in 1978, was equipped with a Plexiglas bubble instead of a windscreen.

The 1980s and 1990s saw a mix of closed and open cars, with the regulations requiring all Group C entrants to be closed. In the early 2000s, after conducting a comparative test at the 1999 24 Hours, Audi decided to enter only open body cars.

The battle between Audi and Peugeot launched the return of closed cars as seen in the LMP1 prototype class. All cars are now closed, with driver protection greatly improved thanks to an arch located above the windscreen. It no longer plays a role in terms of sturdiness, but has become a major element in the aerodynamic lines of the cars and is typically made of lexan or polycarbonate similar to the cockpits in fighter jets. Like on helmet visors, windscreens are now fitted with "tear-offs" (sheets of thin plastic film removed when soiled), sometimes as many as seven for the 24 Hours of Le Mans.

PHOTOS (Copyright - ACO Archives): LE MANS (SARTHE, FRANCE), CIRCUIT DES 24 HEURES, 24 HOURS OF LE MANS. From top to bottom (the evolution of windscreens throughout the race's 100-year history): closed cockpit on the 2022 Toyota Hypercar; lowered windscreen and driver windshield on the 1933 Aston Martin Ulster; the Alfa Romeo fastest in-race lap record holder in 1938; only the windscreen bracket of the winning Talbot-Lago survived the night in 1950 after an impromptu encounter with a crow; the Italian subsidiary of Saint-Gobain greatly contributed to improving the resistance of Ferrari windscreens, namely that of 1961 winners Phil Hill/Olivier Gendebien; of the Renault-Alpines entered in 1978, only Didier Pironi/Jean-Pierre Jaussaud's used this aerodynamic bubble; in 1999, for its rookie participation, Audi conducted a study comparing a closed prototype (R8C, pictured here) with an open one (R8R).