Tech Analysis: Toyota TF107

Toyota were the first to unveil their 2007 car, albeit not the first to run on track, and the launch was low key with the usual Toyota corporate emphasis. But while the team tried to drive forward from their lack of success in 2006, the new car did not at first reflect the huge effort and resources Toyota have focused on the project.

Appearances, however, are deceptive and the car is actually significantly different from last years, with important lay out changes and new gearbox technology subtly hidden behind a familiar colour scheme and old wings.

Last year Toyota went through a lot of change as they tried to build on their best ever season in 2005. The car's development was complicated with a complex sequence of car upgrades which began in the final three races of 2005 and finally ended up with a new B spec car in Monaco in 2006.

The architect of this process, Mike Gascoyne departed in the middle of last season, leaving Pascal Vasselon to be promoted of the head of the chassis dept while Luca Marmorini remained as head of the engine dept, which also suffered uncharacteristic failures during races. But with diligent work from both men by the end of the year the team had regained the ground lost in both pace and race performances.

Heading into 2007 the team were already well prepared on the engine side as development had diverted from a higher revving engine for 2006 to a 19,000rpm-capped engine for the upcoming season. In this regard their end of season race performances with a engine speed deficit to the their rivals suggests the chassis was better than most imagined.

Since Gascoyne's departure, the team focused on aerodynamics and the way they were developed. With a second wind tunnel in construction the team worked to ensure the results from the wind tunnel matched those seen at the track.

The rear suspension also features steeper pushrods and mounts directly to the gearbox © Scarborough (Click image to enlarge)

To do this Toyota were able to measure the loads and pressures on the car via sensors on the bodywork and the telemetry system would provide the data to correlate to the tunnel tests, so that the aerodynamicists could be certain their predicted gain was actually being realised on track.

And so came the TF107, as with almost every team this year an evolution of its predecessor in aerodynamic terms due to the lack of rule changes that often divert the teams attention in that area. The team have been able to optimise a lot of the aero concepts already in use on the TF106 and, at the same time, the engine and gearbox teams were able to develop a new power train and further develop the suspension concepts masterminded by Vasselon for the TF106B.

The first steps in the new car regarded its basic layout. The car's front to rear dimensions have been retained, with the same overall length, but the gearbox is longer which pushes the engine forwards and correspondingly reduces the length of the monocoque.

Toyota were one of the few teams not to develop a longer gearbox back in 2006, deciding instead to lengthen the monocoque, which had a resulting effect on weight distribution and aerodynamics. Additionally the shorter fuel tank area has forced the team to widen the base of the monocoque to retain the same fuel capacity.

The new design has created more space for the coke bottle shape the rear of the sidepods, although Vasselon affirms that the new gearbox's impact on weight distribution was not as important as the amount of ballast they have can already be located to provide more forwards weight bias.

The second critical area in the car's layout was the front of the monocoque. Toyota moved to a Zero Keel with the TF105B and the design was enhanced through 2006. The dimensions of the front of the car are limited by the height of the cockpit opening and the relative positions of the bulkheads at the dash and at the front of the monocoque.

In this year's car these bulkheads have moved upward "3 cm" according to Vasselon, creating more space under the raised part of the chassis and influencing the flow under the floor and around the car.

The shaped wishbone is only an aerodynamic fairing © Scarborough (Click image to enlarge)

There are two compromises in the suspension geometry for this improved airflow, as Vasselon explains: "First, with this kind of concept you sacrifice the camber change. The second one we accept is installation stiffness." As the front suspension moves so little he points out the problems with camber change are minimal, while ever steeper pushrods maintain the suspension's ability to accurately control wheel movement.

The upper wishbone appears to be bent in front profile, this is not actually the case. The curved element is actually the aerodynamic fairing around the steering rod, which is in effect a straight element inside this cover. This shaping reflects the flow off the front wing and flattens it out over the top of the car.

With these fundamental elements in place the balance of the car's aerodynamics falls into place. The launch car did not display the final bodywork planed for the season opener in Melbourne - indeed Vasselon was not at all proud of the 2006-spec front wing on the launch car, despite it gaining cascade elements added to the endplates. The new front wing, developed specifically for the high nose, is expected to appear in mid February.

One aerodynamic feature that Toyota do not appear to have capitalised on is the undercut sidepods. Many observers pointed out that the car appears boxy because of this, but Toyota run a very different aerodynamic strategy around the front of the sidepods as the smaller sets of turning vanes mean they are not as dependant on undercut shape of the intersection of the chassis and sidepod.

The car does feature a new cooling system within the sidepod as the lower revving engine has slightly less heat rejection requirements than the 2006 version.

At the rear the sidepods are very closely mounted to the engine and gearbox, the gearbox itself is not faired as with many other teams, and the titanium casing is actually visible from the sides. This allows he new rear wishbone mountings to be seen. Last year the back of the engine was used to mount the fronts of the wishbones, this year they mount only on the gearbox but this is purely a packaging issue, as a result of the longer gearbox.

The front of the monocoque (yellow) is higher creating more space under the car © Scarborough (Click image to enlarge)

Curiously Toyota have moved away from mounting the rear wing on a strut, a design they used last year. Instead the wing feeds its loads through the endplates and lower beam wing once more. In the resulting space left by the wing support a small pyramid fairing has appeared, leading to suggestions that this was hiding something important.

But Vasselon explains: "It's just a fairing, it's not structural. It's something which is quite logical when you see the flow in CFD".

As the fairing is at the junction of the beam wing and the crash structure, a point which sees the flow sent aggressively upwards by the wing and diffuser, the device probably acts to keep the different flows from interfering with each other and producing unwanted turbulence.

At the rear of the car the important addition to any car for 2007 is the seamless shift mechanism in the gearbox. The Toyota system has been developed in partnership with Williams, who debuted their system last year. This development, and the regulatory loss of engine development opportunity, has seen the engine side of the team working much closer with the chassis side.

Luca Marmorini adds: "Engine and gearbox are more and more a connected group. The (gearbox) concept is coming from Williams and we been able involve chassis side, to develop it jointly."

Despite the gearbox being a Williams concept the actual parts in the Toyota car are unique to them and no components are shared, only the software development spans the two teams. The seamless system reduces shift times and also the requirement for the engine to come off the throttle as much during shifts.

Marmorini claims the amount of time off power is "much less" and adds that this improves the performance of the engine as the flow through the ports is not slowed as much, adding yet more gains to the system claimed to be around 0.3s around a lap.

But Marmorini's main focus is the engine and by diverting development to the rev-limited engine - something he prefers not to call 'detuning' - early last year he has been able to deliver a more developed specification to the FIA.

The pyramid fairing (yellow) is there to tidy the flows around the rear of the car © Scarborough (Click image to enlarge)

A bonus of the engine rev limit is that heat output and fuel consumption are improved but because the engines will be less stressed than the near-20,000 rpm units of 2006, and because the teams do not have to run the race engines on Friday, Marmorini warns that the engines will be used harder. "Because we are changing the way we use the engine, being more aggressive, I am sure we will see engine failures," he warns.

With only the inlets, exhausts and electronics to focus on due to the homologation of the engine, the usual gain in power will not be seen this year. But Marmorini is still determined to increase performance and notes: "We have a clear target to increase performance. We already have benefit in performance compared to last year".

Toyota have made great steps in their processes and basic design of the TF107 - although in some respects this is the car that should have been presented last year. The team have had to wait for this new car to make the major lay out changes everyone else had tackled last year, but the new gearbox and improved aerodynamics are step forward.

It is not immediately clear if this will be enough to take Toyota to their aim of their first win this year, but the direction appears to be clear for the cars development and they should not suffer the problems that afflicted them in 2006.