In the last few races on the straights, Mercedes managed to make up ground against Red Bull – but is it because of the increase in performance or because of complex technology? Mark Hughes delves into the subject, with technical illustration by Giorgio Piola.
At the French Grand Prix in June, Red Bull was able to drive a lower wing than Mercedes in order to be faster on the straights and still be faster over the lap. “If we had driven such a low-wing aircraft,” said Toto Wolff at the time, “we would have lost more lap time on the corners than on the straights.” The RB16B looked like a better all-round aerodynamic package.
WATCH: Hamilton and Mercedes’ pit stop dilemma at the 2021 Turkish Grand Prix dismantled
In Istanbul two weekends ago, the Mercs were significantly faster on the straight than the Red Bull – and a few tenths faster over the lap. That has been the case several times since the Mercedes made a leap in performance at the British Grand Prix in July.
Most obviously, this could be explained by an increase in performance – and that is also in the opinion of Christian Horner and Dr. Helmut Marko happen. “Mercedes are extremely fast on the straights for the downforce that they use,” said Horner in Turkey. “We have been observing that since Silverstone. Something is strange there. “
Graph showing Mercedes’ pace on the straights in Turkey compared to its rivals, based on data from Friday practice
Mercedes insists that there has been no increase in performance. The bottom line is that the difference is the major aerodynamic upgrade Mercedes made for Silverstone, the last major development that went on the W12. But is it possible that an aero upgrade was responsible for such a dramatic increase in straight-ahead performance?
Possibly yes. If Mercedes managed to take full advantage of their lower rake concept by getting a more dramatic diffuser stall.
TECH TUESDAY: Mercedes’ last major upgrade in 2021 that helped Hamilton win at Silverstone
Teams have deliberately instituted a diffuser stall for 15 years or more to increase speed on the straight line. The underbody with the diffuser in the rear creates a lower pressure under the car than the ambient air above and thus exerts downforce on the body. With a high-rake car, more likely than with a low-rake car.
But as the speed of the car increases and the downforce of the underbody and rear wing increases by the square of the speed, the rear of the car is pressed onto its suspension and the angle of inclination of the floor decreases. It’s still building up downforce as the speed increases, but the lower ground angle means it won’t increase as dramatically as if the ground was still at its maximum rake angle.
As the speed of the car increases, the rear end is pushed down
If the rear of the car can be made to sit low enough, the diffuser will eventually stop and no longer induce that low pressure area from the ground. That means an enormous reduction in the car’s downforce, but also a corresponding reduction in air resistance. This increases the car’s speed on the straights that don’t require downforce.
READ MORE: Honda Reveals “Latest Big Development” for Powerplant as They Go All Out to Beat Mercedes in F1 last year
The development is extremely complicated and requires many very powerful simulation tools. The stall point must be tunable from track to track to ensure that it is not close to the stall position in the fastest corners. No downforce is required on the straights, but it is needed in the corners.
Although the static ramp angle of the diffuser – and therefore its performance – is limited by regulation, the higher rake cart effectively increases this angle by driving the entire floor at a greater angle. A large angle diffuser usually works best at relatively high rear ride heights.
The lower angle at which the diffuser runs at a lower incline on the Mercedes means that it performs better at lower ride heights. But it will also be easier to stall at these low ride heights.
A comparison of the Austrian GP bargeboard from Mercedes (above) and its Silverstone model (below)
Mercedes’ Silverstone upgrade included major changes to the front corner of the floor. The bargeboards have been redesigned to match a newly profiled floor edge and newly angled deflectors, suggesting that an attempt was made to suck air out of that front floor corner.
There is only a limited volume of air that hits the car and some will go around the car and some under it. These changes would potentially change the proportion of this division.
READ MORE: Binotto Reveals A Hybrid System With New Specs Was Key To A Strong Ferrari Performance In Istanbul
Could these changes cause the diffuser to stall at a lower speed? When they reach the same stall point at a slower speed, drag is reduced. In this case it could either be done with a bigger wing to get the same straight line, or the same wing for a bigger straight line.
This would possibly give the diffuser stall far more adaptability from lane to lane, which can manifest itself as spectacular increases in speed on the straights on the most sensitive routes.
But it’s just a theory – it can only be more power …
The post TECH TUESDAY: Is Mercedes’ improved straight-ahead speed due to an increase in performance – or something else? first appeared on monter-une-startup.
