Technical F1 Unlocked
TECH TUESDAY: What’s behind Red Bull’s DRS speed gain and are their rivals showing signs of catching up?
Studies of the Red Bull RB19’s floor and suspension have provided many clues about the source of its performance superiority over the field, but one aspect of that performance – how it derives a bigger speed gain from DRS than rival cars – has not been fully explained before.
There is perhaps a vital clue in the profile of the car’s diffuser ramp and in how closely the ramp’s trailing edge meets up with the lower beam wing.
First, here are a few examples of how DRS activation tends to bring a greater increase in speed with the Red Bull than with rival cars.
Top speeds with and without DRS
|Jeddah with DRS||343km/h||333||330|
|Jeddah without DRS||317||313||311|
|Melbourne with DRS||329||323||324|
|Melbourne without DRS||308||307||306|
|Barcelona with DRS||333||332||332|
|Barcelona without DRS||308||310||304|
It’s notable that at Barcelona – the most recent race where we can make a comparison between dry qualifying and race – Mercedes actually found the greatest increase from DRS, so have possibly found a way of countering Red Bull’s strength in this area.
But accepting that the Red Bull has usually found the biggest DRS advantage, even though it is often already the fastest at the end of the straights without DRS, how might they be achieving this? One very plausible theory may be how they have configured their whole diffuser/beam wing/rear wing combination.
With any of the current cars, when the DRS flap of the main wing is closed, airflow exiting the diffuser rises up with the angle of the diffuser ramp and attaches to the beam wing, which in turn directs it to the underside of the main wing.
This increases the downforce produced by the main wing, but that whole cascading aero effect has another benefit: the various low-pressure regions behind the diffuser (created by the beam wing and wing) effectively boosts the speed of the airflow and directs it, so helping it stay attached to the roof of the diffuser. What is happening behind the diffuser influences what is happening inside it.
When the DRS flap of any of the cars is activated, stalling the downforce of the wing, that airflow connection to the beam wing is broken because the top wing is no longer puling on it. So there is a double reduction in drag – that from the top wing itself and that from the beam wing no longer working so hard.
The Red Bull not only features a very aggressively shaped beam wing to maximise the connection between the two wings, but the tip of the diffuser almost touches the lowest part of the beam wing – effectively extending the diffuser ramp to make one big ramp to help the airflow on its way to the top wing.
That in itself should help make this airflow very strong and robust. It should also mean there will be a bigger reduction in drag with DRS because there is a bigger reduction in downforce (all downforce induces some drag).
But there is what appears to be a further subtle tweak in the shaping of the diffuser ramp. Looking at Giorgio Piola’s drawings here, we can see that while the diffuser ramps of other cars feature a single upward angle, that of the Red Bull has a double sweep. It begins at certain angle, which then increases and lowers again, forming a mild concave curve in the roof, before then ramping upwards once more to meet the beam wing.
Why might this be significant? While the airflow can be robust enough to follow the contours of the diffuser roof when it is being aggressively drawn upon by the beam and top wings, it may no longer be able to follow that extra curvature in the roof once it has been denied that help.
In which case the airflow would detach from the surface and the diffuser would suddenly be nowhere near as effective – which would reduce the downforce and drag it is creating.
In essence, this double sweep combined with the close proximity of the beam wing could be more effective in stalling the downforce of the whole floor-diffuser-beam wing-wing combination as soon as DRS is activated. This is not established fact, but there has to be a reason Red Bull has chosen to shape its diffuser in such an unusual way.