This seasons F1 Aero tricks

Battling rule-makers as well as rivals, F1 teams are as inventive as ever; you just can’t always see it

Colin Chapman, who always sought ‘the next big thing’, would have hated today’s rule-bound racing, where every clever idea seems to be rapidly stamped on. But the biggest genie escaped from the bottle on his watch – the invisible art of aero-management. Since wings arrived in Formula 1 drag has become secondary to the great god downforce. Hub-mounted wings, suction fans, skirts and active suspension have all flowered – and been snuffed out to stifle soaring cornering speeds.

It’s cat-and-mouse. Write a new rule and by tomorrow someone will have stretched it. Take the underfloor plank, introduced to enforce a flat bottom and slash ground effect. Designers soon realised that while the plank had to be there, there didn’t have to be any car above the front of it. Cue the high-arching nose exposing the top of the plank, which can be modified by a splitter to offer significant downforce and steer air smoothly under the sidepods. Separating the nose from the wing also freed more wing area (now cancelled by a standard aero-neutral wing centre). More topically, that cut-away above the splitter could allow the plank to flex; sounds a bad thing, but to designers it’s another tempting chink in the rules.

All downforce also induces drag, but the closer you get to the track the better the deal – a lot of extra downforce for little extra resistance. That’s why the rules have lifted the car floor and the front wings. But it’s hard to measure ground clearances at 160mph; if your wing sags under load, you’re into a win-win area. Cue wing stiffness tests to prevent this. So next, teams want to drop the car nose – but the splitter gets in the way, and if you grind down the plank you’ll invoke penalties. But suppose the splitter deflects up when it impacts the track? You get a low front wing, increased suction under the plank, less wear, and the car can ride kerbs harder. This is the ‘flexi-floor’ which teams exploited notably in 2007. Some built in controlled flex; Ferrari actually hinged the splitter at the rear, with a spring strut for adjustability. The FIA brought in deflection tests; designers stiffened the vertical splitter stay so the deflection point was just above the test load. At Monza this year the test load was for the first time applied off-centre. Cat and mouse…

This year we’ve had much talk about the front wing of Red Bull’s rapid RB6. While it resisted static test loads it did seem to run very low at speed. After calls for clarification the test loads were doubled – and the RB6 again passed, as did Ferrari’s F10, accused of the same thing. One theory is that clever carbon-fibre layering lets the wing flex in a non-linear way, deflection rising rapidly after the test point. When everyone has sussed it, there will be a new rule…

As there is over the ‘F-duct’. McLaren’s ingenious speed booster breaks no written rules, but will be proscribed for 2011. However, it’s worth discussing because its core principle – the ‘blown’ wing – is not being banned. F1 rear wings have two sections, of which the upper ‘flap’ magnifies the downforce from the lower. Three-element wings are better but now banned; however the aero industry has long used the ‘blown flap’ principle, which pipes extra air out through slots in the wing, boosting its effect – a ‘virtual’ third wing section made of air.

But a stronger wing brings more drag, and even today’s smaller wings haul a vast bubble of messy air behind them. If you can disrupt the flow pattern when you don’t need all the downforce the flap will stall, losing effectiveness but crucially also cutting drag. Movable aero devices are illegal, but if you can make a flap of air, can you make a movable ‘switch’ of air too?

That’s what McLaren achieved with the so-called F-duct. Air ducted from the overhead intake normally exits below the wing, taking the easier route at an internal fork, but also feeding some forward via a cockpit duct to spill from an opening by the driver’s knee. When he closes the opening using his knee (later a hand) the blocked air diverts flow into the other arm of the fork and out through slots in the upper flap, stalling the wing and giving 4-5 extra mph on demand. McLaren’s forward snorkel inlet boosts the effect. It’s driver-controlled – but no ‘device’ exists.

This idea was rapidly emulated in various ways, though it took some teams half the season to catch up. Most relied on a hand to close the duct, but in the end the teams agreed it was not cricket. So driver control is out, but blown wings remain, some fed by small front openings in the wing, others by ducts through the shark fin (which straightens air flow and gives more consistent downforce), fed from the main air intake or extra flank openings. Now there is some talk of automatic F-ducts, which would choke an internal duct over certain speeds to divert the flow.

A similar principle has resurfaced within the diffuser, which extracts air from underneath. But there’s another source of fast-moving gas – engine exhaust. Today’s rules ban body projections such as bargeboards and exhaust ‘chimneys’, pushing designers to smooth and slim the rear bodywork and move exhaust outlets down low. It is possible to feed the exhaust directly under the diffuser to radically boost ground effect, but lifting off the throttle cuts this suddenly, unsettling the car, which is why this went out of favour in the ’90s. Williams and Mercedes have revived the idea by guiding the exhaust under an open-fronted diffuser, a less critical method, but most teams are blowing over the diffuser and through the suspension This smooths out the draggy wake of the big rear wheels and extracts more air from the diffuser - if you can defend components against the furnace heat. Some teams have had to redesign suspension mounts to keep them clear. Every change you make affects something else; an F1 team’s job is a constant trading of benefits.

Same with the rules. Safety vs spectacle; speed vs cost; designer vs law enforcer. The ‘next big things’ get smaller, but they’re no less crucial.

With thanks to the Lola Design Office for their consultation. For more information on Lola click on to www.lola-group.com