Analysis: Lotus to use bespoke Red Bull gearbox and hydraulics from 2011

Although the rumours suggested it will be a complete Renault rear end for Lotus Racing, today the team announced it will in fact use the Red Bull gearbox and hydraulics from 2011.

Equally unexpected was the confirmation that the technology will not simply be Red Bulls 2011 RB7 design. But a part Lotus designed gearbox. Silvi Schaumloeffel from Lotus exclusively telling ScarbsF1.com “It’s a bespoke gearbox for us and we have been in contact for several weeks and have been able to progress the design”. Thus the 2011 Lotus already has the Gearbox design considered as part of its initial philosophy.

This deal underlines the determination of Lotus Racing to get a foot hold into the midfield. Their race results this year have been undermined by hydraulic failures. Lotus Racing are one of the two teams using the complete Xtrac gearbox and Geoff Willis technical director of HRT has been critical of the units packaging in comparison to current F1 standards. Clearly if Lotus want to progress then they need to resolve the reliability issues with the cars rear end. Moreover the team also need to improve their aerodynamics, at the rear of the car this is largely constrained by the gear case design. As the gear case itself forms a large obstruction to the airflow approaching the diffuser. Plus the gearcase dictates the rear suspension geometry, springdamper packaging and the hydraulics packaging.

As a route to a cheaper and quicker entry into the Formula, the FIA allowed new teams to run with an Xtrac gearbox and hydraulics, mated to the specification Cosworth Engine. Lotus have taken this approach, of the new teams only Virgin chose to make their own gearcase, the bespoke case gave Virgin a unique rear wishbone geometry.

Traditionally teams have always developed their own transmissions and hydraulics, albeit with assistance from specialist manufacturers, but the concept, design and assembly has been in the teams’ hands. While gearboxes have increasingly been reliable from both detail design work and the increased control from electronics, the F1 cars Achilles heel has recently been the hydraulics package. The hydraulics package is complex both in its operation and the number of moving components controlling the various systems around the car. A modern hydraulics system now controls: gear selection, clutch, differential, reverse gear, throttle control & power steering. Any number of components can lead to the system breaking: pump failures and leaks, plus failures of the valves or actuators.

To build up the knowledge and resources to develop a complete gearbox and hydraulics, requires time and a huge investment. Equally with restricted testing, problems with any part of the system could hinder pre-season testing and lead to yet more race retirements. As a medium term option Lotus have taken the route to sub contract these systems to another team who already have the knowledge resources and a proven product. Several teams have offered these systems to other teams, Williams are known to be marketing their rear end, while before the Red Bull announcement, Renault were believed to offering their rear end.

The option to take a team’s gearbox and hydraulics is logical; the choice of any of the current team’s solution would be equally attractive. Why Lotus chose Red Bull is not yet clear. Perhaps the fact they are able to offer a bespoke product, rather than the same specification as raced by the factory team.

Looking at Red Bulls recent history on transmission and hydraulics does not initially paint a positive picture. In the first years of Newey’s tenure at Red Bull racing their systems were unreliable, it took the recruitment of Geoff Willis to iron out the faults, since then and following his subsequent departure, RBR have been as reliable as their rivals in these areas. Red Bull were also late to the seamless and carbon fibre trends on gearbox design.

In contrast the influence of Newey on gearbox design shone in 2009 when he designed the RB5′s gearcase to accommodate the new aero regulations. With smaller diffusers mandated he took advantage of gearbox packaging to improve flow to the rear wing and around the diffuser. Only the advent of double diffusers upset this philosophy. Newey’s 09 gearbox took a low line approach, placing the differential low down and moving the springs and dampers from atop the gearcase to low down, by use of pullrods rather than pushrods. This placed the torsion bars splayed vertically aside the gearbox and the dampers running longitudinally alongside the case. While the heave damper and inerter sat inside the front of the gearcase, either side of the clutch input shaft. Having these components in this location placed them low from an aero and CofG perspective, plus they sat in the shadow of the engine, thus once faired in beneath bodywork presented no interference to airflow alongside the flanks of the gearbox. In contrast to the low line mechanicals, the wishbones were mounted unusually high, the lower wishbone was well above the floor (leading the space for the exhaust blown diffuser in 2010), then the upper wishbone sat very high up on pylons cast into the top of the gearcase, the rear legs of the upper wishbone taking a secondary aerodynamic role in directing airflow the rear wing.
It was only later in 2009 that the team switched from cast aluminium to a carbon fibre gearcase. The switch in material having no major effect on the original designs packaging.
For 2010 Newey’s gearbox needed to accommodate the double diffuser, the original concept was largely retained, only a raised differential and revised wishbone geometry (to optimise the EBD) were altered. Newey did tell me the benefit of pullrod was marginal, it being better to stick with the known concept than alter the entire case for pushrod operation. With the ban on double diffusers in 2011, Newey’s original 09 concept will see benefits once again.

Of course Newey’s gearbox layout won’t necessarily be copied, as the Lotus gearbox will be a bespoke product, Mike Gascoyne’s Cologne based design team will be able to influence its design. However it would be logical for the team to follow some of the concepts used by RBR in 2009. Although perhaps the choice of a cast metal casing would be more effective for Weight VS cost, Carbon would be expensive and 2011 cars are constrained by the demand for forward weight distribution that RBR faced in 2009. Gascoyne does have a record of innovative gear cases, with his split carbon fibreCast Ti case at Renault, then Toyota using fully cast Ti cases and latterly MidlandSpykerForce India with cost effective cast aluminium cases.

For Lotus to truly be a leading team they will need to build up their own gearbox and hydraulic departments. This deal for RBR technology will allow them to naturally evolve these resources, while racing their bought-in gearbox.

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