F1: The Mercedes W09 in detail, making the best even better
Thursday saw Mercedes unveil the car that could keep their incredible run of world championships going, the W09.
Once you look past the Halo and the lack of shark fin, the car will be immediately recognisable as the bodywork details are all based on the 2017 W08. But that’s not to say the car isn’t heavily updated, the key changes are inside and largely aimed at rectifying the maladies of the old car’s handling.
Even before the end of the 2017 season, rumours abounded about the design direction of Mercedes 2018 with regards to wheelbase and rake angle. With the W08 being the longest F1 car of the year by some 60mm and running much flatter to the ground, than the tail up stance of the Red Bull for example.
A fan myth has evolved that a long wheelbase affects the car’s ability to race on tight street circuits, whereas the reality is that the ability to turn around tighter corners is a factor of a great many things and not just wheelbase.
Most teams stretch the wheelbase to create more space for aero bodywork like bargeboards or a longer floor for more downforce from the underbody. Mercedes prowess on faster more open tracks is more to do with their levels of downforce and less to do with the car being a long lazy handler.
It has been confirmed that the W09 is the same length as the W08 and from my observation it isn’t greatly different in rake angle either. Although it's conceivable that higher rake set up could be experimented with, any change in wheelbase would be a massive engineering task for the team mid season.
Part of the difficult handling of the 2017 car was the loss of the complex hydraulic suspension systems over the winter. Without these systems to closely control the ride height of the car’s underfloor, the car became sensitive to the less controlled changes in the car’s attitude around the lap, as the downforce levels fluctuated with changes in ride height.
The car either needed different suspension or less sensitive aero, which could have come with a loss in total downforce. Development for the W09 was aimed at these two areas without the loss in downforce.
Suspension development is not so visible at the front, but when even the drivers are mentioning it, it has to be a key factor for the car’s handling. The front suspension retained the basic 2017 layout, with the wishbones mounted as high on the chassis as possible. This clears up airflow under the suspension for better airflow towards the sidepods.
Also, the angle of the wishbones relative to each other is slightly more angled. This is known as anti-dive and affects how the suspension compresses under braking, helping keep the ride height stable on the approach to turns.
While at the rear the upper wishbone is mounted in a very different attitude. This can have several effects. James Alison, the team’s chassis technical director, suggested this was for aero reasons, but the change in the angle also affects how the suspension compresses under braking and acceleration, this could also be a factor in taming the handling.
We could look closely at the bodywork, but it's clear this car, like most of Mercedes launched since their return to F1 in 2010, is bound to change on the outside. Over the years Mercedes has chosen to make bodywork just for the first few days of testing before a big idea gets revealed thereafter.
Increasingly in the past two years Mercedes have chosen to go for intricate bodywork, surfaces broken up with serrations, slots and added vanes from nose to tail. This level of complexity isn’t likely to go away with the updates to the W09, so from already highly detailed aero parts, it's only going to get even more exotic.
From the front wing, the cape vane added under the slimline nose (unique to Mercedes this year), bargeboards and slotted floor edges, the Mercedes echoes last year's car. In terms of external surfaces there’s little genuinely new to pick out. One small detail is the winglet over the exhaust, this replaces the larger ‘monkey seat’ wings used in recent years and sits within the much smaller space allowed for such winglets this year.
In contrast to a lot of other teams, Mercedes are keeping the middle inlet sidepod front design. It’s clear they haven’t repositioned the inner crash structures to follow Ferrari’s high-top design, so even if they change the sidepod bodywork it won’t look like the Ferrari.
An area pointed to by many observers is the rear bodywork being very slim, and while the coke bottle shape at the rear is slim, this is partly an optical illusion. Mercedes make the front of their sidepods much wider than other teams, as this then slims towards the rear, the inswept shape looks much more aggressive.
POWER UNIT PACKAGING
The remaining width at the back of the coke bottle shape is largely to duct hot air from the radiators. Wider versions of the bodywork will be run at hotter races, but the near 2°C temperature at Silverstone for the shakedown obviously wouldn’t demand them! However, Williams Technical Director Paddy Lowe mentioned at their ‘season’ launch that Mercedes have some innovation in the packaging of the Power Unit. Mercedes technical director for their power units, Andy Cowell was coy about what this was, but did affirm that steps had been taken to reduce the Power Unit’s impact on the bodywork wrapping around the back of the car.
Some of the cooling for the hybrid systems is achieved with air fed down from the roll hoop, and these units and the associated ducting really benefit from downsizing this year. Both as the airflow into the roll hoop is affected by the Halo, but also as the lower this ducting routed over the top of the engine can be, the sharper and more effective the shark fin can be.
We can see the roll hoop inlet itself is wider and split in greater number of separate inlets, by the roll hoop inside. There now being a distinct “A” shape to the split inside the inside, this formed by the metal inner roll structure, covered by carbon fibre bodywork.
More directly the power unit has had a major redesign over the winter, aimed at improving efficiency. Mercedes again wouldn’t be drawn but the convenient numbers of 1000hp and 50 per cent thermal efficiency are being bandied about by the press, if not confirmed by Mercedes, who merely state “over 950hp” from the power unit. Even in 2017 Mercedes' excellent reliability didn’t require the full set of four power unit’s elements allowed per driver, so this year’s even more stringent 3/2 elements per driver should be less of a risk for Mercedes, unless there's been an unexpected hitch with their winter development.
During the winter break Mercedes released a number of YouTube videos about the car’s development. One of these featuring the car’s first “fire up” shows a number of details, including the exhaust tailpipes. From these clips it’s clear the exhaust that featured a smooth (possibly 3D printed) step section back in 2017, has required an even more pronounced step in the exhaust to rise up over the rear wishbone mounting and then back to the regulatory height for the tail pipe exits.
We will have to wait to see the full 2018 W09 aero package. Some of this could be as late as the first GP in Melbourne, but from the other changes made to the car in light of the lessons learnt in 2017, Mercedes may have cured the car of its ill handling.