The centenary of the 24 Hours of Le Mans was a celebration of endurance racing. The parade of historic cars honored the past, which was then followed by the challenge between the Hypercars to bring attention back to the present. There was not even a glimpse into the future, with the presentation of the A424_β, the prototype with which Alpine is preparing to compete in the premier class. From the engine to the aerodynamics, the French car displays some solutions that will make it easily recognizable in the midst of the Hypercar platoon.
Power Units
The A424_β is designed according to the LMDh regulations, which impose greater restrictions than the Hypercar regulations from which Toyota, Glickenhaus, Peugeot, Ferrari and Vanwall were born. First, LMDhs can only be built around a frame supplied by one of the four homologated companies. Alpine has chosen to rely on Oreca, the same company that gave birth to the chassis of the competitive Acura that won the 24 Hours of Daytona on its debut. The A424_β also relies on hybrid rear-wheel drive, with just 50 kW of support from the electric motor, in contrast to the 200 kW of hybrid Hypercars, which also benefit from all-wheel drive. Finally, the power unit of the LMDh sees the presence of various standard components: the battery of WAE, the ex-Williams Advanced Engineering; electric motor from Bosch; six-speed transmission by Xtrac.
Nonetheless, Alpine can still express a certain design identity in its creature, starting with the combustion engine. The thermal is developed in synergy between Mecachrome and the Viry-Chatillon experts, the same ones who take care of the Formula 1 V6s. Taking advantage of the limitation of bench testing for the Formula 1 power unit, the endurance program was able to develop the A424_β engine on the same dynamometers. Again from Formula 1, various solutions converge to improve the level of reliability, helping to reduce engine wear and keep it as close as possible to the maximum power limit, even as mileage and temperature increase.
Password: simplicity
Bruno Famin, general manager of Alpine Racing, explains how in a regulation that limits maximum power, engine design is guided by simplicity and reliability. So for the thermal we chose a 3.4 liter V6, without pursuing smaller displacements and dimensions chosen instead by the competition to reduce weight and improve responsiveness when changing direction. By comparison, Peugeot runs a 2.6-litre, Ferrari runs a 3-litre V6, and Acura even runs a 2.4-litre. The displacement of the Alpine is instead very close to the 3.5 liters of Toyota, an engine however initially designed to release 1000 horsepower, as required by the first Hypercar regulations.
Always with a view to simplicity, the A424_β mounts a single turbocharger, against the biturbos of most of the competition. The exceptions are Cadillac’s naturally aspirated V8 and Isotta Fraschini’s monoturbo V6, the latter engine however remaining more compact in displacement, stopping at 3 litres. Alpine’s 3.4-liter V6 monoturbo also mirrors the same characteristics as the Mecachrome engine introduced in 2018 for the LMP1 program. It will be interesting to find out if other aspects have also been maintained, such as the bank angle of 180° and the positioning of the turbo between the two banks, solutions both useful for lowering the center of gravity, to the advantage of tire exploitation and constancy of the aerodynamic load.
Transfer from Formula 1
On the occasion of the launch of Le Mans, Alpine declared that they converge on the A424_β the hybrid technologies developed in Formula 1. Such statements could be confusing, given that batteries and motor are subject to standard supply among the LMDh. However, the synergy with the Formula 1 team does not lie so much in the hardware as in the hybrid system management software, the development of which is the responsibility of the manufacturers. Several engineers involved in the Hypercar and LMDh programs have made no secret of how careful management of the electric motor can influence the car’s behavior when cornering, stability under braking and driveability under acceleration.
The refinement of the software also makes it possible to optimize battery charging during the race. With the same amount of energy usable for each stint, a parameter set by the BoP, improving the energy efficiency of the power unit helps to take on a smaller quantity of petrol, reducing the weight in running conditions. Acura has repeatedly spoken about its collaboration with the Honda Formula 1 department and there’s no doubt that Alpine will also benefit from a similar relationship.
Aerodynamics
The Hypercar-LMDh regulations impose limit values for the maximum load and minimum aerodynamic resistance that can be achieved. The designers’ goal therefore does not focus on finding maximum aerodynamic efficiency, but on keeping it as close as possible to the regulatory limit in all conditions of use, reducing its sensitivity to balance changes, to the various heights from the ground and to rotations in curve.
From the exhibition model present at Le Mans, no multi-profile front wing hidden in the nose transpires, as instead done by Ferrari to rely to a lesser extent on the bottom, a component that is more sensitive to variations in height. In its place, however, on the sides of the front end, however, they make their appearance two sets of diveplanes. Very interesting is the solution studied for the rear-view mirrors, hidden behind the front wheel arches to reduce their contribution to aerodynamic resistance.
Like Ferrari, BMW and Cadillac, Alpine rejects the classic layout of the sides, in which the radiator intakes open to the sides of the passenger compartment. In contrast, A424_β exhibits a body entirely closed at the sides, drawing the cooling air through two internal ducts that extend right into the muzzle. Lastly, cooling grilles open above the sides, limiting the evacuation of hot air from the rear vent of the bonnet which, on the other hand, affects the overall aerodynamic performance.
Overall, Alpine focuses on simplicity, while adopting various solutions that distinguish it from most of the competition, such as the closed sides and the monoturbo V6. What makes the difference from an aerodynamic point of view, however, is above all what is not seen, namely the bottom and its stabilization through the suspensions. Lastly, great curiosity revolves around the hybrid system management software, with logics similar to those of Formula 1 and probably also those of Formula Ewhere the Renault group is present with Nissan.
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