Tech Analysis: Mid-test report
Two days down in Bahrain, two to go. Although many were expecting an array of updates on the cars for the second of only three test sessions this winter, only a few teams have so far sported additional components as focus slowly turns towards performance and set-up work.
I do not know the ins and outs of set-up work but I would imagine the teams will be going through basic changes (anti-roll bars, ride heights, dampers, wing levels) and requesting feedback from the driver. A catalogue of data is recorded alongside this feedback so the engineers can begin to understand how the aerodynamic characteristics of the car they have built in the wind-tunnel/CFD interacts with the mechanical performance that they discover out on track.
Jerez is notorious for being an unreliable circuit to explore performance due to the track’s surface, low temperatures and unique layout. Therefore the Sakir circuit gives teams their first real opportunity to assess how set-up changes affect performance. Continually putting the miles on a new car is also essential as new issues are constantly revealed. Dealing with a new problem is crucial in terms of reliability and also if the fault reemerges during a race weekend. Knowing how to fix the issue quickly and efficiently could have a major impact on the Championship.
Along with set-up changes, further aerodynamic work has been carried out over the first two days in Bahrain with teams running with pitot tube arrays to see if components are behaving as desired. Pitot tubes measure air speed and the aerodynamicists will be looking for a correlation between the result they take in the wind-tunnel and those out on track. Correlation between the two sets of data are important in continuing aerodynamic development: bad correlation and you cannot make any sort of progress as the parts you development could be unreliable. This is a problem Ferrari have experienced in more recent years.
The tube arrays can be mounted at various intervals along the car although a more common area of analysis is done just behind the front tyre and ahead of the diffuser. The induced vortices and the wake that the tyre creates at speed can damage flows moving around the sidepods towards the rear of the car, hence why this area is critical area of design.
Along with pitot tubes, Flow-Visualisation (Flo-Viz) paint is applied to the bodywork to assess how airflow is moving across it. The paint is more like a dye and can easily be removed by just a wipe of a cloth once it has served its purpose. The engineers will take photographs of the patterns that the dye produces when air passes over it and send them back to the factory for analysis.
Detachment of airflow is a more common sign that things are not working aerodynamically and this can be seen visually using Flo-Viz. Areas of the dye that don’t appear to be at all influenced by the airflow passing over it are regions where the airflow has detached.
With the basic test procedures covered, let’s move onto some of the items the teams have brought with them to Bahrain…
The public debut of the E22 was a highly anticipated one and the car looks really well thought through. Having cast our initial gaze over the detail around the twin ‘tusk’ nose solution (explained when Lotus released a render of the car last month), further detail around the sidepods and particularly towards the rear of the car proved intriguing.
The front wing has received an healthy amount of change to cope with the narrower width regulations with three vertical fences making up the endplates to push airflow around the front tyre. These fences are accompanied by an assortment of vanes and cascade elements that are more aggressively profiled than last year.
The unique nose design is complimented by a pair of turning vanes beneath the chassis that aim to direct airflow towards the heavily undercut leading edge of the sidepod.
Flicks and turning vanes on the front brake ducts have been heavily revised and appear to be more refined than some of the solutions already out there at this stage.
Lining the top of each sidepod lies a horizontal blade that attaches to the vertical airflow conditioners that flank the sides of the car. These blades drag airflow passing over the sculpted ‘pods towards towards the top of the diffuser in an attempt to regain some of the lost downforce the teams are experiencing this year.
Unlike any other team, Lotus have opted to offset the exhaust slightly. The regulations allow the exhaust to be offset by 100mm either side of the car’s centreline and this makes way for a central rear wing pylon to be attached directly to the rear crash structure without any deviation in its profile. Other teams have overcome the issue of having the exhaust as an obstruction to the crash structure by either using two pylons, attaching the endplates to the floor or adopting the ‘Y-lon’ (Marussia and McLaren).
Lotus have also managed to retain its extreme diffuser design (outwash as well as upwash) despite the lack of a blown diffuser.
The Hinwil-based squad had always planned to bring further parts to the second test and we have already seen these incorporated over the first two days.
A new front wing was introduced from the get-go, featuring a slightly modified profile and upper flap as well as modifications to the endplates. This was accompanied by new sidepod airflow conditioners and a horizontal blade (right). Although we have already seen the pair of them in the launch images ahead of Jerez, the team finally debuted them in Bahrain this week. The toe angle of the ‘pod conditioner in particular is quite aggressive as it aims to deflect front tyre wake away from the sensitive undercut area beneath the air intake.
The team also placed a Y100 (Monkey Seat) winglet above the exhaust between the two rear wing pylons this week, its aim being to induce an upwash effect at the rear of the car and extract further performance from the rear wing and the diffuser.
Minor updates for the Woking outfit as the team start to realise the potential of its MP4-29. Although Kevin Magnussen grabbed the headlines on Day 2, times are still irrelevant at this stage (particularly as Magnussen was the only man to run the super-soft tyre).
Small fins attached to the front wing endplates neatly cover rear-facing infrared cameras to monitor front tyre temperatures. Although some teams are already doing this, McLaren have installed them in a much more aerodynamically efficient manner.
The team have also lined the base of the ‘Y-lon’ and surrounding area with gurney tabs to aid the upwash effect at the rear of the car. However the team had some overheating issues along the top of the rear crash structure on Day 1 as the thermal reflective tape was visibly scorched directly ahead of the exhaust’s jet.
William Tyson - a Mechanical Engineering student at Swansea University - has been writing about the technical side of Formula 1 since February 2013. After joining the Richland F1 team for 2014 he has continued to establish himself as a more rounded technical analyst whilst maintaining a healthy following on his blog.