Despite the fact that it was the new radiator intakes that caught the attention of the McLaren upgrade in Singapore, this was probably not the most significant aerodynamic change in the MCL36. Formula One technical expert Mark Hughes takes a closer look at McLaren’s changes in Singapore, with illustrations by Giorgio Piola.
McLaren is striving to give the car more consistent aerodynamic performance at all the different rear-riding heights the car will see, to give a more consistent balance across the cornering speed range.
The rear ride height of a car lowers the faster the cornering gets, as aerodynamic forces compress the car’s suspension. In slow-speed turns, as the rear ride height increases, this can cause the airflow to separate because that air is no longer moving so fast and is therefore less powerful in flow patterns.
Teams strive to maintain as consistent a vehicle’s balance between high and low speed as possible to create the largest operating window possible. The wider this balance window between the front and rear of the vehicle across the speed range, the more overall downforce can usually be created. Maintaining good airflow across the bottom of the rear chassis at low speeds is critical to this.
When designing the different surfaces of a vehicle that define this airflow, it may be worth losing some high-speed downforce if that allows for a more consistent flow pattern and is less likely to stall through the undercarriage at lower speeds.
That’s something James Key, McLaren’s chief technical officer in Singapore, hinted at. “You can’t see it, but there’s a lot of detail that’s starting to develop in the basement now. A lot of surfaces and things that don’t make sense when you just think about the real basics of Earth Effect, but actually make the differences. The parts you can’t actually see are Some of the most effective parts.”
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Regarding the basics of ground-effect references cited in the main references, the greater the air pressure difference between the lower floor (low pressure) and the upper surface of the vehicle (high pressure) generated by the venturi tunnels into the floor, the more downforce is created. But the larger and more powerful these tunnels are at creating low pressure, the more likely they are to stop at low speeds.
This is where the lower floor needs the most help from the upper body surfaces to keep the pressure difference strong at greater riding heights encountered at lower speeds. So it’s possible that what Key describes as changes that “don’t seem to make sense” actually increased performance.
The eye-catching changes to the radiator intakes — along with changes to the front floor flange, inlet intake vanes and floor edges — are just part of feeding the powerful upper body that helps the underfloor in the rear corners of the car.
“This bundle has had a lot of mechanical changes under the skin to allow some shapes to develop,” says Key. This may be a reference to the angle of the radiators behind their new inlets. The structure that forms the top of the entrance has been scaled back (forming the “shelf” at the bottom of the entrance, which remains in place).
This rear scrubbing allows for a deeper angle than the downward slope of the entire sideboard and this slope is a powerful part of the accelerating airflow that feeds the rear corners of the car to form the pressure difference between the lower and upper surfaces there. Tilting the radiators more sharply will allow the upper intake to be reduced backwards.
Changes to the front edge of the floor, tunnel vanes and floor edges are consistent with the enhanced force of this airflow to the rear corners of the car, possibly even at the expense of the amount of air used to feed under the body. Only a large volume of air is available, and aerodynamics are constantly looking for the most effective split between feeding the lower and upper body surfaces.
The pressure difference created by these two flows is what creates the downforce, but that difference varies with vehicle speed and rear ride height.
Lap time trumps everything in deciding where that compromise lies and McLaren is polishing that compromise. It offers clues to F1’s future design direction as other teams begin to understand why Red Bull and Ferrari are so effective.
“This upgrade is a logical step,” Key continues. “It follows what we did in modernizing France but there are some conceptual changes to it as well, which are very different. This is the first step towards a new concept.”
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