What's wrong with the Williams car?
Sky F1's Mark Hughes on Williams' tough start to Formula 1 2018 and what the problem might be with their new car...
Last Updated: 22/05/18 6:46pm
"[The problems] are exactly the same as three months ago. I'm not the right person to go too much into the details. We know exactly what is our weakest part of the car. We've started a project which should help us to understand better, improve it and hopefully solve it completely. But it's not a question of one day or one month - probably it's even more.
"So we have to be patient. Miracles will not happen. Coming to Barcelona, I was expecting to be in a difficult situation and Practice One was even more difficult than expected. We will try to help our main drivers with the balance of the car, to make it easier for them to drive.
"Performance is a different story. We have to fix our many issues, in order to think about performance and trying to attract the maximum from what we have. We have to somehow understand we're in this situation, but apart from being slow, it was nearly impossible to keep the car on the track. That's something we need to change, in order to make our drivers' lives easier."
Robert Kubica's comments about the Williams FW41 aligned very well with not just the timesheets, but observation out on track.
The car looked like it wanted to spin as soon as the wheel was turned. Its front end looks stiff and wooden, with not enough compliance to absorb loads without the wheels locking, and its balance looks awful. The whole car looks to be operating at a frequency different from that which can be managed by a human being. Barcelona, with longer corners than most, meant that it spent a greater proportion of the lap in this unbalanced state than on short corner circuits.
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The programme Kubica refers to in helping the team understand the car better is a root and branch analysis comparing simulation with track reality and trying to find the source of that variance. The initial suggestion is that the car's aerodynamics change radically in yaw (ie as soon as the car is turned at an angle) - which is a pretty fundamental problem, given that turning a corner involves exactly such a situation…
The aerodynamic philosophy of the current generation of F1 car is largely based upon directing the airflow from the outboard edges of the front wing to go around the tyre and interact with the flow being directed from the transition between the front wing's main plane and the mandated neutral section in the middle (referred to as the Y250 for reasons that don't need detain us here).
As air flows over two different angles of a surface it will create a vortex of spinning air - and a particularly strong one is created by this Y250 transition, and that vortex is directed to just ahead of the sidepod. The incredibly complex shapes on the endplates create another vortex, which meets just above that created by the Y250. These two vortices spin in opposite directions - and that has the effect of drawing the air around them into the gap between them, increasing the speed of the flow all the way down the side of the car on its way to the gap between the rear wheel's inner face and the external outer shoulder of the diffuser.
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The air exiting from that gap merges with the air exiting the diffuser from the underfloor and the two flows draw upon each other, which pulls the air faster through the underbody, creating more downforce.
But the whole process is prefaced very strongly on getting those vortices coming off the front wing directed to the right place. If one or other of those vortices are somehow going somewhere other than where they're directed as soon as the steering wheel is turned, it effectively would switch off much of the whole airflow regime of the car.
If that indeed is what is happening, understanding and correcting it might be a very long project. On the other hand, it may all reside in one innocuous detail.
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