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Williams BMW FW26 Technical Review by Craig Scarborough Image Credit:Scarborough Even though McLaren had run their new car in December testing, their decision not to formally launch the car gave the privilege to Williams BMW to put on their new suits (and boots) and be the first to present their car to the world's media. For several years Williams have produced evolutionary cars and with engine rule changes and car that by the seasons end in 2003 was as fast as any, little was expected to surprise on the new car. But this was wide of the mark as the cover was drawn from the car the sharp intake of breath from the audience reflected striking nose of the new car. Clearly Williams conventional, if independent school of aerodynamics has found a completely new solution. If the nose rightly takes the spotlight, other areas of the car remain conservative with some areas revised and not receiving the attention they perhaps deserve. 2004 Rules Aside from the timetable changes to the practice and qualifying sessions, there have been few technical changes for 2004. Of these the most far reaching has been the move to a single engine per weekend format. Under previous rules precautionary engine changes were over night or following a failure, resulting in up to a handful of engine being used per car over a race weekend. With most of the teams support the FIA suggested a single engine could be used to reduce costs, applying a "10 grid place" penalty to any car requiring an engine change over the weekend. This doubling of engine life (now up to 800Kms) has put a great strain on the engine designers. For the chassis engineers a few aerodynamic changes have been made, the rear wing has been regulated to have only two upper elements over the previous three (excluding the lower beam) and the endplate has been enlarged. Following Ferraris lead engine covers have been shrunken no longer meeting the dimension maximum, to deter this engine cover now "have to" meet this imaginary line drawn up from the rear axle line. Away from aerodynamics the chassis impact tests have been incremented forcing the structures departments to work harder to get the structure both safe and light. I am the Walrus Image Credit: Scarborough At first glance the nose is at the same time dramatic and ugly, brutal perhaps. Williams have gone away from convention so far, that the solution will need more time to fully understand its effect. Technical director Patrick Head was adamant there were gains from the set up despite Frank Williams admitting "its not very pretty" and that it did lose some valuable advertising space on the nose. But in order to gain a greater step in aerodynamic performance the team researched this approach soon dubbed the "Walrus" by journalists at the launch. The aim to maximise downforce, minimise drag and satisfy cooling demands lead the team to run aerodynamic studies starting with computer based CFD studies before moving onto the windtunnel for the more promising solutions. Aerodynamics are dominated by the flow coming from the front of the car. By the way the flow passes over the front wing, between the front wheels and around the centre of the car and the way this is all affected by the attitude of the car to the road is critical. New wing shapes, high noses, bargeboards and twin keels are all well developed solutions to manage this flow. Antonia Terzi the teams' head of aerodynamics sought to eliminate the part of the nose above the front wing, allowing more freedom for the flow both over and below the car. This in contrast to the Ferrari\McLaren approaches to actively use the underside of the nose cone to interact with the wing. In shortening the nose cone the need to still mount the front wing remained, the dagger shaped pylons lead forward from the truncated nose to meet the front wing, which is largely the same the "W" concept adopted in 2003, yet now the wing is in almost free air. Williams retained a derivative of their forward mounted turning vanes and the front wing mounting pylons match their curve, appearing to guide the flow from the front wings dipped sections in between the wheels and out through the turning vanes. Thus keeping the flow under and over the wide nose to clear to efficiently feed the sidepods and rear wing, the pylons extend up the nose to form a fence keeping this flow from spilling along the sides of the car too early. While twin keel could be considered a design concept best matched to the dipped wings of 2001-2003 and not so relevant with the "W" format wings increasingly adopted on the late 2003 cars. With the noses' square cross section now placing more importance on the upper and lower surfaces, twin keels have been adopted to move the suspension mounts away from the wide flat under nose shape. Curiously the keels are not in line with the pylons, as perhaps Jordan have adopted. Yet the Williams solution matches the slim-ness of Jordan's' layout to the length and angle of McLarens. Patrick Head further commented that the set up subtly improves the "aerodynamic map" where the cars downforce changes little with changes in pitch roll or yaw. Indeed the side profile of the nose is considerably smaller in surface area to a conventional nose, probably aiding turn-in or yaw resistance yet further. Structures Image Credit: Suttons While the research to get the odd-looking aerodynamic concept proven and accepted by the management, the work started to get the nose and keels structurally sound. Head admitted that Twin keels were investigated by Williams before with some aero gains, but were offset by the structural penalties. With a "Walrus" concept the aero gains in twin keels were much greater and countered the weight penalty of the structure to support what Head described as "an off axis load from the very highly loaded forward leg of the front wishbone" Equally the nose has proven to be a structural nightmare, as it is required to meet impact tests and decelerate the impact load in a controlled manner, never exceeding certain "G" levels. This is usually achieved over the much longer length of a conventional nose cone. Head explained shorter nose was made to work "by the way it collapses and the length of that collapse" in order to meet the test requirements. Credit goes to Brian O'Rourke, Williams head of composites, who has use of a secret impact test facility with the Williams factory to get the nose to accept the 3/4 ton load in a controlled crumple. One issue raised with the new nose was the potential for the pylons to penetrate a competitors a car in a side impact, simulations and physical tests were carried out to ensure they broke away safely. Image Credit: suttons Clearly visible from the mould lines on the front bulkhead, the monocoque has been moulded from three majors pieces, a lower tub, then two left and right mouldings to form the upper two thirds of the car. Internal bulkheads are visible through the footwell, but this does not rule out the lighter option of a largely bulkhead-less design. Elsewhere the chassis is considerably stronger, especially along the cockpit sides while being lighter than last years. The other crash structures at the side and rear of the vehicle have been improved. Mechanical layout Image Credit: Suttons Williams went against their previous practice of long wheelbases last year and adopted a short layout, largely through a smaller gearbox and fuel cell. This year the fuel has had a small decrease in capacity, Williams appearing to place the smaller volume lower, rather than shorter or narrower fuel tank. Also potentially affecting wheelbase is the engine and gearbox, Mario Theissen of BMW said the engine was slightly smaller and Patrick head said the gearbox has gone up from six to seven speeds, yet the extra ratio has been packaged within the same length. Overall the car retains a very similar wheelbase to the FW25. Seven speeds were adopted this year not so much due to the powerband of the BMW P84 engine, but in order to give the range of ratios through out the weekend, the team using lower revs Friday and Saturday morning to preserve the single engines life. Additionally head said of the new aluminium cased gearbox was " Lighter than last year, smaller and much cleaner aerodynamically down the sides" and Sand cast in the same BMW plant in Landshut (Germany) as the engine. The partnership between BMWs engineering and production teams with Williams also extends to the initial "rapid prototyping" of the casings and manufacture of Gears, Cranks and camshafts. Along with a revised gearbox, the rear suspension uses a McLaren-like layout. Placing the rear leg of the upper wishbone very high and the forward very low plunging through the bodywork just behind the flip up, the damper and torsion bar layout have been further refined form 2003 with little shaping required on the slim engine cover to hide the innards. Up front the wishbone layout further progresses on William's previously horizontal upper wishbone, which now appears to droop, creating an unusual geometry leaving the experts to discuss the merit of its camber control and roll centre location. Torsion bars on the front have been mounted incrementally lower than the FW25 and extending longer, to allow for more wheel travel. Probably for impact protection the steering rack has moved inside the footwell of the monocoque, rather than being bolted to its front.

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