2006 San Marino GP Technical Review

After the three flyaway races, Formula One made its traditional return to Europe and Imola.

The three-week break since Australia allowed the cars to be returned to their factories, and a chance for all the teams to do some testing. Thus, the San Marino paddock was full of revised cars with most teams arriving with at least some new parts.

The Imola circuit was revised this year with one of the chicanes being altered, but the character of the circuit remained the same. Imola is an unusual circuit, built on a hillside. The gradient changes are mixed with short straights punctuated with chicanes.

Although this suggests a stop-start nature, Imola is in fact quite a flowing track. Its hills and straights demand power, while the chicanes require good brakes and suspension that allows riding the kerbs.

This year's race was warmer than usual, too, making tyre choice more difficult. This, matched by the short pitlane, encourages shorter stints on softer tyres.

Kerbs

A lap of Imola demands the drivers to ride over the kerbs in order to 'straight line' the chicanes, so as to get a good lap. Even with the Variante Alta being made into two closely coupled corners - rather than a kink in the road to flick through - the ideal set-up remains one that allows a car to ride the kerbs without unsettling the chassis.

At first one would assume this just demands softer suspension, but this would compromise the car too much around other parts of the lap, which demand stiffer springing.

The car's suspension is managed by five elements: the tyre, the spring, damper, anti-roll bar, and third spring.

While the tyre creates most of the suspension travel, it is not tuneable beyond tyre pressures. Then, the anti-roll bar and third spring are designed to reduce suspension travel in certain attitudes, mainly to manage the car's attitude to improve aerodynamics and not to react to kerbs.

This leaves the dampers and springs. In normal use on a smooth track, the spring/damper only moves the wheel an inch or two. Any more, and the floor would hit the ground, upsetting the aerodynamics and grinding the plank along the track.

But with kerbs rising many more times than the normal wheel travel, something has to compensate. An F1 car's springs are not coil springs, as you would see in a normal road car, but torsion bars. These are simple metal tubes splined at each end, one connected to the chassis and the other rocker operated by the pushrod.

The tube resists the twisting force to provide the spring effect; the spring's rate is altered by different thicknesses of the tube's wall or the tube's length. The longer the tube, the more travel it can accommodate.

As F1 cars do not provide a lot of space for long torsion bars, the tubes are sometimes split into two - one sitting inside the other to provide twice-effective length. Renault and now Toyota appear to adopt this format for their rear suspension.

Also, some teams - such as Ferrari - simply make their torsion bars longer and stick out through the bodywork at the back of the car.

So with the springs able to travel further to give the wheel travel, the damper also needs to react. When the car corners on a normal track, the damper may only travel half an inch. When it hits a kerb, it may need three times that.

With the damper providing a stiff rate for normal use, it can't react to the larger and faster movement required over a kerb. Thus, the dampers are equipped with a "blow off valve".

This valve sits within the usual damper valves but reacts to sudden large movement of the damper. It releases the usual damper valving, making the damper very soft, which allows the longer travel.

Thus, when the wheel hits the kerb, the damper reacts to let the wheel rise easily over the ridges, and then resets itself as the wheel returns to its usual position. This "blow off" damping is adjustable, and teams set it up to suit the drivers' style over the kerbs, allowing that perfect lap.

Technical updates

Ferrari

The team arrived with many revisions to the car, the major one being a new gearbox case to accommodate revised suspension geometry.

This new rear suspension was aimed at improving tyre usage; at this early stage in the season, doing major revisions to the gearbox casting is a huge undertaking. In investing their resources into this redesign, Ferrari had to delay other related projects - the main one being the introduction of a seamless shift gearbox.

However, technical director Ross Brawn explained that the improvement in tyre usage was worth more over a race distance than seamless shift and hence tyres were the priority.

New endplates (yellow) on the shoulder wings were part of a new aero for Midland © Scarborough (Click image to enlarge)

Although the new rear-end was being kept under wraps, the longer torsion bars used for Imola's kerbs were now faired in. Also, the angled fins in front of the front suspension were flattened off to reduce their downforce effect for this track.

Midland

Although Midland are still working under a tight budget, new aero parts have been developed and were tested in the week before the race. Furthermore, straight-line testing was used at Silverstone to prove the parts matched the wind tunnel result.

One of the most noticeable changes was the endplate to the shoulder wing. The old teardrop-shaped endplate has been replaced with a larger squarer version (Yellow).

The larger endplate probably works to keep the wake off the front wheels from going over the sidepods and upsetting the rear wing in a similar manner to Honda fins in a similar position.

A raft of Honda aero updates include deflectors around the cockpit and a new mid wing to move downforce rearwards © Scarborough (Click image to enlarge)

Honda

There were three visual changes to the Honda car for Imola, and the most unusual were the deflectors added to the side of the cockpit.

These arched and curved fins pick up the wake from the front wing and pass it down and around the sidepods. This improves the quality of the flow to the rear wing and moves the aerodynamic balance backwards. It may also help balance the revised front wing - the bi-plane arrangement used in the opening races was dropped for the 2005-style, more deeply curved wing.

Behind all this was a new mid-wing: the flat, wide version was replaced with a narrower span axe-head shape (yellow), having its front edges drooping slightly.

Lastly, a small addition was the simple fairings (yellow) added to the front suspension (yellow).

BMW

Revised cascades over the front wing work with the fairing over the wishbones © LAT/XPB (Click image to enlarge)

Having suffered cooling issues requiring the removal of panels in the sidepods, BMW arrived at Imola with a new sidepod shape.

New chimneys are also matched to winglets that are much more curved, while the louvered sections over the radiators and exhausts were altered. The rearmost louver panel is now removable and left in black carbon fibre to hide the unsightly brown burn marks that are left on the other pristine white paintwork.

At the front of the car, new cascades over the front wing were matched to large fairing added over the front wishbones. These at first appeared to be structural and in place to alter the front suspension geometry, but when removed the fairings exposed the usual wishbone mounting on the chassis.

Renault

A small fin (Yellow) on the wishbone has been added inline with the bargeboard © Scarborough (Click image to enlarge)

A new engine specification was made ready early for Giancarlo Fisichella; the new unit originally planned for the Nurburgring has increased revs.

A unique aerodynamic touch on the Renault has gone unnoticed all year. A fin on the front top wishbone has been added in line with the bargeboards. Although a small detail, no team have gone as far as adding small devices like this, instead keeping the wishbone profile a simple aerofoil shape.

Super Aguri

Another race and another detail alteration to the car - this time the rear wing gained a small winglet above the crash structure.