How Red Bull's flexi-wing actually works

TECHNICAL REVIEW: RED BULL’S FLEXI WING

Red Bull’s Formula One Team has been regularly courting controversy throughout 2010. In addition to the questionable management practices that have created tension between the team's drivers, Red Bull has faced repeated criticism of their car's design. Earlier in the year they were forced to rebut suggestions they had been running an illegal form of ride height control that gave them an unfair advantage during qualifying. Now the World Championship leaders face fresh allegations from rival teams who are claiming the RB6 contravenes the rules due to its unique front wing design.

Photographs taken at the German Grand Prix showed Red Bull's front wing flexing at speed and dropping the endplates close to the ground. This was confirmed by carefully presented TV footage a week later in Hungary. It would appear that Red Bull’s front wing flexes by approximately 30 millimetres and the advantage of this movement is reportedly worth around one second per lap.

This has resulted in a huge controversy because flexible wings are strictly against the technical regulations. Red Bull is arguing their car is perfectly legal because it passes the FIA tests for flexibility, but all that means is that Adrian Newey has cleverly designed an elastic wing that remains firm during scrutineering.

Red Bull’s competitors are yet to work out how this transformation occurs. Ferrari has also introduced a flexible front wing but their design is not as efficient and does not deform as much as Red Bull's version.

When asked about the unusual properties of the wing McLaren’s Martin Whitmarsh said "In truth we don't understand it" but there are a number of credible theories that detail how Red Bull gained their advantage.

THE MOST LIKELY SCENARIO – CARBON FIBRE CONSTRUCTION

In the same way that a brick wall is stronger when the bricks are interlocking, carbon fibre is stronger when the layers of fibre are perpendicular to each other. There is some suggestion that Red Bull has produced their front wing with less individual fibres crossing at right angles. This would make the wing flexible enough to bend under load, but retain its stiff shape when stationery in the pitlane. The FIA would be unable to detect movement in the wing because the loads they use in scrutineering are not representative of those on the racetrack.

The FIA tests for movement in the wing by applying the equivalent of 50kg of downforce. However, at full speed a front wing can generate over 200kg of downforce. Red Bull could feasibly have built a flexible wing that's strong enough for the scrutineering test, but begins to deform when the actual loads increase.

MORE COMPLEX CONSTRUCTION METHODS

Red Bull could also have layered the fibres within the wing so they effectively ‘buckle’ once the load reaches a certain point. With enough trial-and-error testing, the team could tune their carbon fibre wing to pass the FIA test at 50kg but significantly buckle under a heavier load. Although this would be harder to engineer, it would also be harder to detect during scrutineering since the deformation would not be linear (as it would not flex in proportion to the load applied). It's difficult to see any evidence of this on television which suggests Red Bull may not be pursuing this particular idea.

FRONT WING DESIGN AND LAYOUT

The actual layout of the front wing is possibly the most significant factor that contributes to its flexibility. Red Bull’s wing has a cluster aerofoils and winglets that are integrated into the design near the endplates. These don't appear on other cars where the winglets are spread more evenly across the full width of the wing. These additional flaps near the endplates would push them closer to the ground at speed, but would have absolutely no impact at all when the car is not moving.

It’s also quite likely that the wing has been designed to twist backwards under aerodynamic loading. This means the wing moves closer to the ground because it is rotating slightly and sliding downwards at an angle. The FIA only tests for vertical movement, so they would be unable to detect the full elasticity of the wing if it's actually moving horizontally as well.

MECHANICAL ADJUSTMENT

A more interesting suggestion, although one that is not very likely, is that some sort of mechanical system is being used to alter the wing's characteristics.

Imagine a steel cable that runs from the top of the nosecone to the wing tips which prevents them from moving (a little bit like the support cables found between the wings on a biplane). Now, if that hypothetical cable was loosened, the tips would be given the freedom to flex and would naturally fall closer to the ground. If such a concept could be implemented inside the wing, even using something as simple as a cable, it would enable to wing's elasticity to be switched on and off by the driver.

Such a system may sound fanciful but could possibly be integrated into the existing mechanism that adjusts front wing. Drivers are allowed to alter their front wing's angle of attack by six degrees from their cockpit with a small motor, and Red Bull could be using this system to stiffen or loosen their design. The small motor could potentially tighten a cable, or adjust a device similar to an anti-roll bar, that allows the driver to switch the wing's flexibility on and off as required.

It’s very easy to bend a plastic ruler when it's lying flat, but if you rotate it by 90 degrees it is impossible to bend it across the narrow edge. Something similar inside Red Bull’s wing that rotates could help change the characteristics of its movement.

THE NOSECONE

Another more sinister suggestion is that Red Bull has devised a way to make the entire front end of their car flexible to help bring the wing closer to the ground.

Television footage suggests this isn't the case because the endplates appear to bend away from the centre of the front wing which remains stable. However, Ferrari has introduced the same concept and has been unable to get as much movement as Red Bull so perhaps there is something else at play.

If Red Bull has introduced a nosecone that is flexible at high speed, it's possible this wouldn't be picked up by the FIA who are simply measuring wing deformation.

In theory, the front of the car could be also brought closer to the ground by introducing a flexible splitter, or 'tea-tray'. The splitter runs beneath the front of the car as a forward extension of the floor. If this could be made to flex upwards, the car would have more aggressive rake and this would lower the entire front end of the chassis. In 2007 Ferrari made their splitter flexible so that it would disturb the air running into the diffuser at speed, thereby reducing drag in a straight line. The FIA subsequently clamped down on moveable floors but if Red Bull has somehow got around the restriction it would help them bring the front of their car to the ground.

WEIGHTS AND SPRINGS

In 2006 Renault developed the controversial mass damper which was banned partway through the season. This was essentially a sprung weight in the front of the car that countered the movement of the chassis over bumps. It made the front of the car more aerodynamically efficient by keeping the bodywork stable at a constant height. Although it didn't lower the front wing specifically through corners, Red Bull might be using a similar concept of weights and springs to flex the front of their car. Although it’s highly unlikely that Red Bull has such a system, there is some loose evidence to suggest that something along those lines may exist.

VETTEL'S CURIOUS FAILURE

At Silverstone, Sebastian Vettel’s RB6 suffered a rather odd front wing failure during Saturday morning practice. Usually when a front wing suffers some sort of structural failure it breaks away from the car at the supports. Interestingly, Vettel’s wing took the whole nosecone with it, and did so without any direct impact or nasty ride over the kerbs.

It was a very unusual component failure. Either there was an extra force on this part of the car to induce the breakage, or the nosecone was particularly susceptible to aerodynamic loading. There are some suggestions this is the result of the nose flexing, or some sort of weight inside, to move the front of the car closer to the ground. It’s very difficult to spot any evidence of this on television but looks can be deceiving.

FIA SCRUTIEERING

Before the next race at Spa Francorchamps the FIA will increase the intensity of their flexibility tests. They will place a load equivalent to 100kg on the front wing and will only allow linear flexibility in proportion to this load. That should satisfy the teams who believe Red Bull and Ferrari are up to no good, although some may argue that it doesn’t go far enough.

Even if the new scrutineering test doesn’t force Red Bull to alter their design, it may offer a few clues as to how their wing actually works.

UNDERSTANDING THE FLEXI WING

Other teams will copy the design as soon as they understand the concept. The most likely scenario is that Red Bull’s front wing is made from a special construction of elastic carbon fibre, and also bends backwards slightly to convert horizontal force into vertical movement when the air hits it at speed.

Innovation is far from dead in Formula One.

Posted by Martin Porter. - Follow him on twitter @mpondaweb.

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• Thanks for your comment Nick, and I agree that the technical side of F1 is very intriguing!

  I don't think your suggestion is crazy at all. In...
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