Tech blog: F1's summer progress

After Hungary's high-downforce track, the Formula 1 field take on two low-drag, but very different, races: Spa and Monza.

Where Monza is predominantly straights, Spa is largely high-speed curves, so the cars do need downforce to negotiate some of the toughest corners on the calendar. However, as they are tackling these turns at such high speeds, the cars can produce enough downforce with relatively small wings.

As a result, teams develop special wing packages just for the Belgian Grand Prix. Because it's the rear wing - and all the drag it creates - that sets the car's top speed, it gets trimmed the most. Some 5-10cm is taken out of its depth, reducing its power.

Such a small wing needs a special profile, not simply a flattening of it. Teams will also alter the wing's shape across its span to further reduce the drag produced at the wing tips.

Along with this, the endplates need modification to reduce the number of drag-reducing louvres above the wing. Some teams will also slim the beam wing's aerofoil sections and remove the Y75 winglet mounted above the tail-light.

Mercedes ran a new rear wing, with tweaked endplates © XPB

MERCEDES

Still pushing hard with development, Mercedes arrived at Spa with a new rear wing, although it didn't run its latest front wing that was raced in Hungary.

Not only were the new rear wing's elements a Spa-specific shape, but the endplates now featured the popular slot near the leading edge and the increasingly common vanes on the endplates' outer sides.

These vanes fit within the allowable width of the rear wing endplate and broadly align with the airflow sweeping up behind the car. Lotus was the first team to introduce these late last year.

RED BULL

Red Bull's new parts this year have all been about detail, rather than changes in concept. More components arrived for Spa, including the sidepod fins and new diffuser tested in Hungary, along with a new nose.

Changes to the diffuser are a rare example of Red Bull following other teams. Both Lotus and Mercedes run diffusers in a shape that curves aggressively outwards and not only upwards.

Red Bull introduced a flatter nose specifically for Spa © XPB

This increases the expansion of airflow in the diffuser, pulling more from under the floor to give better downforce. Such is the curvature of the diffuser's sidewalls that they exit on the side not simply out of the rear. Ferrari has also tested such a design.

More visible on the car last weekend was the new nose shape. Red Bull gains a little front downforce from running a slightly down-swept nose. For Spa, less front-end aero load is needed to balance the low drag/downforce rear end, so the latest nose was flatter, featuring a higher tip.

There were also detail changes around the front wing and endplates to further manage front-end downforce.

LOTUS

Although I'm told major development has now stopped on the E21, parts signed off some time ago were run last weekend, including a revised engine cover, the passive drag reduction device and some sidepod changes.

However, the biggest update was a planned extension to the wheelbase that was put off until Monza.

The long-wheelbase change isn't aimed at stability on the long straights of Monza and Spa, but rather aerodynamic benefits.

A long-wheelbase E21, aimed at improving aero, will roll out at Monza © XPB

In F1, the already very long wheelbases mean straightline stability/cornering agility is not a factor of the wheelbase. As a result, wheelbase is largely decided by the aero team placing the wheels and major components in the best arrangement to get the airflow passing around the car.

The plan, I understand, is to move the front wheels forward 10cm to gain better airflow over the sidepods. By moving the wheels forward relative to the chassis, the nose and front wing need to be repositioned because their dimensions are partly set by the front axle position.

This change requires new crash tests for the nose and the revised front suspension, and other changes need durability testing back at the factory to be 100 per cent certain of safety. As reported by AUTOSPORT, these tests were not completed ahead of the GP this weekend, hence the delay in their introduction.

What can be seen on the car is the new engine cover. This is a hybrid of the Williams-esque shrunken engine cover raced at Silverstone with the passive drag reduction device. This way, the team can get the aero benefits of both designs in one package.

Allied to the engine cover update and perhaps in expectation of the long-wheelbase car, the sidepod fronts gained new fins. Since its launch, the E21 has raced with a horizontal vane over the sidepods. Now the sidepod add-ons are made up of three twisted vertical vanes.

These produce the same effect as the flat vane, creating a downwash over the sidepods that both redirects the exhaust plume and also produces a high-pressure region over the sidepod.

SAUBER

After a slow start to the season, Sauber's upgrades are coming at every race now. There were new sidepods in Hungary, and for Spa there were new front-wing cascades and a return of the drag reduction device, although these parts weren't raced.

Sauber tested, but elected not to race, its passive DRS system © XPB

The new cascades are a simpler, flatter winglet without the outer mini winglets. Instead, there's a vane where the cascade winglet meets the endplate. It's somewhat similar to the Lotus design.

Further aiding the redirection of airflow from this vane is a further vane fitted above the cascade winglet. These changes may be aimed more at Monza, because their effect is all about reducing drag from the turbulence off the front tyres.

The team also tested its drag reduction device again at Spa. Like the Lotus system, this stalls the rear wing at high speed to give an extra performance boost. However, unlike Lotus', Sauber's set-up is far more neatly integrated into the car.

The roll hoop inlets can be completely removed and replaced by a streamlined fairing, and one of the exit ducts comes out under the beam wing and does not obstruct the airflow at the back of the car.

McLAREN

McLaren played with a low-drag set-up at the rear © LAT

In preparation for Monza, McLaren tested a low-drag set-up with a rear beam wing all but split in the middle.

The usual highly cambered aerofoil section of the beam wing above the rear crash structure was cut away by some 15cm.

Allied to this, McLaren also had Lotus-style vanes on the rear-wing endplate.

CATERHAM

As with Charles Pic's car in Hungary, Caterham raced both machines with the older stepped nose again.

TORO ROSSO

Although not known to be a team struggling with the tyres, Toro Rosso followed Mercedes' lead and fitted infrared tyre temperature sensors to the front wing during practice. These face directly rearwards and are centred on the tyre's tread.

This way, the team can get an accurate temperature reading unhindered by the normal off-set position the sensors are mounted in.