Web Exclusive Articles
« back to listing
Cranfield MSc Motorsport Group design day
Cranfield University invited PMW to attend the presentation day for its 2013 students, who were tasked with improving on track performance of an existing race car through active aerodynamics
by John O'Brien
‘Throw away the rule book, and indulge yourself’ must be the single sentence that every race engineer secretly longs to hear at work. For the 2013 graduating students of Cranfield University’s Motorsport Engineering degree, that was exactly their brief.
More specifically, it entailed designing and developing active aerodynamics for the Reynard Inverter race car. A former student of Cranfield, and now guest lecturer, Adrian Reynard’s involvement in the course has been very much hands-on, with the ex-racer actively involved in the module as well as helping fund the more intensive parts of the course.
The overall aim of the project was to design and evaluate active aerodynamic devices and concepts to improve the performance of the Inverter by reducing drag characteristics, whilst improving downforce levels.
Work focused on revisions to two cars. Students were split into four groups, with two teams per car. One team would focus on the frontal section, whilst the second would work on revisions to the rear of the car, before coming together to quantify there performance benefits on the overall car.
Group work took in computational fluid dynamics (CFD), before wind tunnel work on a 50% scale model and then ultimately track time on the Silverstone National circuit to correlate the findings.
Team one’s proposals took an extreme approach, with enclosed front wheels, vortex generators located on the extreme edges of the front wing, an active tea tray beneath the car, side skirts that verged on ground effects, and an extensive fascia plate that joined the wheel arch covers with the central tunnel of the car. Significant gains in downforce were achieved through the addition of the sideskirts (10.6%), the ‘blown floor’ (12.2%) and by simply removing the existing tea tray beneath the car (9.7%). Counter productive to this was the inclusion of winglets which saw a reduction in vehicle performance, and a 3.9% increase in overall drag.
Proposals such as the diverters located on the front wing achieved better results, with drag reduced by as much as 17.5%. The chosen configuration of revisions, when using CFD, resulted in a 25.6% reduction in drag over the base model when travelling at 45m/s.
Team two worked on the rear of the first car, and proposed a ‘dynamic downforce control’ system that centered around a split rear wing, the two sides of which operated independently to allow differential control in corners, of the rear wing. The complex system was accompanied by a revised wing profile, new taller endplates to prevent pressure bleeding, and a LMP style shark-fin.
For a full size version of team two's poster, above, click here.
The active aero built in to the complex rear wing structure, is controlled by a single actuator that operates to an actuation time of 0.14s. This, is in line with a professional racing driver pressing the brake pedal and achieving full brake pressure – thus not disturbing or unbalancing the car whilst the changes in aero occur. The revisions proposed by team two reduce drag on the Inverter by 26%.
Team three’s work focused around active and re-active dive planes, using an actuated canard to increase downforce in cornering that can be retracted in to the wheel arch to reduce drag on longer straights. This was combined with an under-floor stalling device, which is controlled by a forth pedal mounted alongside the conventional pedalbox. Additional revisions to the Inverter fell under the umbrella of passive changes, and included smoothing the frontal area of the car, avoiding pronounced edges, an extended front splitter and a side diffuser which mimicked the performance profile of a Formula 1 double diffuser. The findings for team three showed a reduction in drag of around 10%, equating to a 2.10% reduction in lap times, around Silverstone.
The final team created a variety of concepts, the most visually impressive being the heavily louvered rear overhang, to induce a low-pressure region at the back of the car. This was combined with a DRS type device and an active diffuser beneath the car capable of changing the levels of drag and downforce created. Powered by a pneumatic actuator, the entire system added a total weight of 6.8kg to the car, but this was offset by a significantly improved lap time around Silverstone circuit, some 1.25 seconds quicker than the time set by the baseline car.
The voting audience selected team two – pictured left and made up of Kevin Boutsen, Edouard Carton, Monica Cuadrado, Tom Kempynck, Michael Rhodes, and Morgan Trolle – as winners, giving them the MSA award.