The Innovation on the W11 Better Than DAS
Why Mercedes' Dual Axis Steering is their 2nd most impressive feature
DAS is probably the most eye catching innovation to enter F1 for some time, maybe even since the blown and double diffuser saga. But despite it taking centre stage this year, Mercedes' most powerful performance boost has actually come from the opposite end of the car.
It's a lot less visually impressive or as obvious but the serial winners of F1 have pulled a(nother) masterstroke.
What Mercedes essentially did was sweep the lower wishbone as far back as possible to create much more working area for the airflow to enhance the performance of the diffuser. Because if you think about it, like a longer wheelbase, the further back you can package these bulky elements the more free working space you have to manipulate and clean the airflow to create downforce and find lap time.
In addition to this, in creating a low pressure area at the rear of the underfloor the diffuser effectively speeds up the airflow over the whole area of the underfloor - and the faster that air flows the more downforce is created. But what does that have to do with the suspension?
The more powerful that flow, the greater the air pressure differential between the over-body and the underbody – and the harder the air will be pulled through the floor by that diffuser (higher discrepancies between pressures create more suction - a bit like having two oppositely charged magnets). In sweeping the lower wishbone so radically far back, it cleared valuable space in what is a tightly packed, but aerodynamically powerful area.
They achieved such a structure by reducing the angle between the rearward and forward legs and making it much narrower than you'd want. The front leg mounts far behind the gearbox, while the rear one integrates in with the crash structure.
This narrow angle is however quite problematic. To make the wishbone's bracing against the gearbox so strong over such a small angle it's got to be heavier - a problem which explains itself. Not only this, but their arrangement also feeds those loads over a smaller area, putting much more strain on the gearbox
This explains why they had the gearbox sensor issues at the first race in Austria, although largely rectified by rearranging the wiring looms (not the components themselves). It's worth noting too the high suspension spike loads through the rear suspension to the gearbox over the kerbs will have probably played a part in the problem.
The picture (from Giorgio Piola - obviously) shows the rear leg feeding into the rear crash structure; and you can also get a sense of the narrowness of the aforementioned angle.
Last year’s arrangement, shown below, had a much wider angle between the two. Racing Point currently use last year’s arrangement on their RP20 (from the W10) but for next year are set to switch to the more aerodynamically powerful current Mercedes system. I guess they're waiting for next year to copy this year's car ;).
So the W11's DAS system may have grabbed all the headlines in pre-season testing, but this much less obvious innovation could actually be worth more in lap time for Lewis Hamilton and Valtteri Bottas as Mercedes chase yet another World Championship double in 2020.
Credit - Piola (again)