Why adjustable wings needn’t affect gear ratios
January 16, 2011
It’s a frequent sight in modern Formula 1 – a driver gets close enough to the car infront to slipstream him down the straight, but just before he’s built enough speed to pass, he hears the all-too-familiar sound of a V8 engine bouncing off its rev limiter at 18,000rpm.
It’s one of the reasons overtaking in the pinnacle of motorsport is such a rarity. To squeeze every last tenth out of the car, mechanics pick gear ratios so that cars hit the rev limit in top gear at the fastest point on the track. The result is that, while slipstreaming reduces a car’s drag, theoretically increasing its top speed to allow overtaking, in practice the cars’ speeds are limited by gear ratios chosen for different circumstances. If longer gear ratios were used, giving the cars enough headroom to slipstream, it would impair their performance in clean air.
The FIA’s latest solution to the overtaking issue is to introduce an adjustable rear wing, capable of shedding drag while in the tow of another car to make passing easier. Already, people are voicing concern that, because a car’s top speed is decided when its gear ratios are chosen, the loss of drag from the adjustable rear wing will have a negligible impact on overtaking. A closer look at how the FIA have chosen to impliment the adjustable wing reveals this needn’t be a problem.
In brief, the cars of 2011 will be equipped with adjustable rear wings which, when activated, will shed a considerable amount of drag. In races, these can be deployed when a driver is within a second of the car in front, at a point on the circuit designated by the FIA. Concerns over how the rear wing will impact on gear ratios seem to stem from the assumption that the FIA will choose the straight where the cars reach their highest speeds as the deployment zone.
The FIA has an inglorious history of shooting itself in the foot, but choosing the longest straights for the rear wing would be quixotic even by its standards. Consider this: at a particular circuit, cars reach their top speed of 300kph at the end of straight A. With the rear wing activated, the theoretical drag-limited top speed rises to 315kph, but because of the gear ratios picked before the race, the car starts bouncing off the limiter at 300kph.
At straight B on the same circuit, the cars reach 280kph before they hit the brakes. If the rear wing were activated on straight B, the cars would now reach 295kph at the end of the straight; more than enough to pass cars without the wing activated, without threatening the rev limiter. If the FIA wishes to avoid an almight headache for teams, and a potential embarrassment for itself, it will place the deployment zone away from the fastest point on the track, be that on the second-longest straight or otherwise.
Of course, these concerns could well turn out to be academic, as unrestricted use of the wing in qualifying means teams may well choose gear ratios which allow them to hit top speed with the rear-wing activated on the longest straight (315kph, to use the example above). But if teams compromise their Saturday performance by choosing shorter gear ratios, it could pay dividends on race day, when activation of the rear-wing is restricted.
Formula 1 teams are no strangers to striking a balance between compromises and, come Bahrain, the adjustable rear wings will be one more variable in an ever-growing list. The key question is whether commentators will be able to make sense of it to the fans.