James Allan published a
story on outwash front wings this weekend which I find quite intriguing.
SEPANG – SPECIAL TECHNICAL UPDATE
Posted on | April 2, 2010 | by James Allen | 82 Comments
Ever wondered why F1 designers go to such extraordinary lengths to refine the design of the front wings and particularly the endplates? Top teams bring something new in this area to almost every race.
When you drill down into this area of the car’s design, you realise that it has far more effect on the aerodynamics than the much discussed double diffuser – probably five to ten times more effect!
Double Diffusers grab all the headlines, largely because of the legality issues, but they are nothing like as important to an F1 car as the barely discussed “outwash” front wing.
So this week we’re going to give the outwash wing, the spotlight it deserves.
The front wing tip vortex and the front wheel wake are the most important things to control in F1 aerodynamics. You want to stop them going in places where they do too much damage. 50-60% of the aerodynamics of an F1 car is concentrated on this vital area.
In 1998 when F1 cars were new rules narrowed in width from 2 metres to 1.8 metres the cars ended up with the front wing endplate alongside the edge of the front tyre. Designers developed very sophisticated solutions to manage the front wheel wake and wing tip vortex in order to get lots of downforce.
But then in 2009 the FIA brought in a radical change of aerodynamic rules, one of which was to make the front wing wider. Now, with the tips of the front wing sitting directly ahead of the front wheels, it was a completely different ball game.
The more experienced engineers in the pit lane, who had been around before 1997, or who had worked on IndyCars or Le Mans cars, knew that it would be desirable to produce an outwash effect from the front wing endplate, which would generate a low pressure area on the outside of the front wheel. It would also avoid the front flap being blocked by having a wheel right behind it.
Toyota were one of the first to try it, thanks to the intervention of veteran aerodynamicist Frank Dernie, and it was one of the signature items on the Brawn car. Engineers say that the outwash front wing was the single biggest step from 2008 to 2009, far more than the double diffuser.
The huge step in performance McLaren made last July was largely down to introducing an outwash front wing for the first time.
This year every car in the pit lane has one, with varying degrees of sophistication.
Red Bull has a very pronounced vortex channel underneath the end of the wing. If you look really closely there are lots of new details, sometimes tiny, sometimes very pronounced every race weekend, because the front wing, and particularly the tip of it, is an incredibly sensitive area and the tiniest change to a turning vane can make a big difference to the car’s performance. Ferrari made a good gain in Melbourne with the new wing endplate detail we featured in the Australian LG Technical Report.
Some of the new teams like Lotus and Virgin have fairly crude front wings and refining them will bring a big step forward in performance, moving them closer to the midfield teams. Lotus has an upgrade to its front wing coming for Spain.
For Virgin Racing, whose designer Nick Wirth insists on using only CFD (computational fluid dynamics) in the design and development of his car, this will be a real test and the whole pit lane is watching to see how well he does it.
This is because the main weakness of CFD in F1 design is in the area of modelling front wheel wake. It is so complex and changes with every tiny movement in the attitude of the car. Rival engineers, who also have big CFD capability in their factories, say it’s not possible to accurately measure front wheel wake using F1 standard CFD alone. This is because the air flow in the wheel wake is unsteady and the only CFD programme capable of modelling unsteady flow is owned by NASA and costs $1 million a month to run!
If the rivals are right then this will hold Virgin racing back. But if Wirth comes up with a major step in this area, then the others may begin to concede that he has found an affordable way to do away with wind tunnels.
But Virgin’s development may be held back in any case by the urgent need to build a larger fuel tank and Wirth’s attention will be focussed on that. It is a huge job, not just lengthening the chassis and redesigning the floor and bodywork, but the wiring harness will not be long enough. There are two options there; build a new one which is a huge task, or lengthen the old one, which is sub optimal and could introduce reliability problems.
Renault introduced a sophisticated new outwash front wing solution in Australia and it contributed a significant amount to the car’s improvement.
This front wing development could explain why all the sudden Renault in the hands of Kubica can give problems to Hamilton or Force India can consistently get into the top ten in qualifying.
