The curious case of the Drag Reduction Device

The curious case of the Drag Reduction Device

If you follow the Lotus F1 Team on Twitter, you will know that they have been releasing teaser shots over the past week of their 2014 challenger, the E22. Today they released an image with the focus being on the side of the chassis and, in the background, a blurry-looking airbox. Interestingly, it revealed that the new chassis will not feature the “ears” either side of the airbox that are used to function the Drag Reduction Device (DRD).

The DRD is a complex system that alters the amount drag created by the rear wing main plane. When active, the device reduces drag and increases top speed, although when inactive the rear wing behaves as normal in producing downforce. It is a totally passive system but one that requires a lot of attention to detail and long hours to set up correctly. This is proven by the fact that it has only been raced once since its inception in 2012.

Kimi Raikkonen raced DRD at Silverstone 2013

Kimi Raikkonen raced DRD at Silverstone 2013

If working correctly, DRD is an excellent aerodynamic solution to the issue regarding moveable aerodynamic devices. Following on from the ban of the ‘F-Duct’ used by the majority teams in 2010, the regulations were changed such that the driver could not have a major impact on the aerodynamics of the car. As DRD is passive it fits within the regulations and the FIA are yet to question it over the “spirit of the regulations” argument, so development has continued over the past two years.

Lotus have been running the device in Free Practice since early 2012, Mercedes since Spa 2012, Red Bull brought theirs to the 2012 Young Driver Test in Abu Dhabi and Sauber recently joined the bandwagon last year… So why have we only seen the device race once throughout its entire development process?

Let’s start with the basics of the system to understand what the complications are. The “ears” allow airflow to pass into a passage which descends towards the base of the engine cover. These inlets can vary in shape and size depending on the individual airflow characteristics of each car.

The airflow then reaches a junction: upwards lies a periscope arrangement that exits beneath the rear wing, and ahead is an exit that passes horizontally beneath the Y75 (Monkey Seat) winglet. The junction is separated by a fluid switch: a section of pipework that can change the course of the airflow without any moveable parts.

When the car is travelling at low speed, the airflow passes through the ears, down the passage and straight out of the exit beneath the winglet. As the car’s speed increases the pressure within the system changes as a higher, faster volume of airflow guides its way through the system. Once a desired speed is reached the fluid switch is activated, diverting airflow up the periscope and onto the rear wing above.

When this occurs the normal airflow passing beneath the rear wing is disrupted by the air that is projected by the periscope at right angles, causing the airflow to separate and therefore reducing drag.

This is all very well and good, but the devil is in the detail. You don’t want to be cutting drag in the middle of Blanchimont or you would just fall off the road. Yet you want the device to be active at as low a speed as possible to maximise its effect.

Tuning the activation of the fluid switch for one track is relatively straight forward, but different circuit layouts require different activation speeds. This is the real stumbling block for this device as teams spend painful hours in practice setting it up when they could be doing more valuable evaluations on other updates, tyres, engine mapping etc. Representing DRD in the simulator also has its complications as it does not take into account wind speed/direction and general circuit conditions.

You therefore have to wonder if Lotus just struck a bit of luck at Silverstone last year, got it all set up with relative ease and went from there. This begs the question as to whether all the months of hard work fine-tuning this piece of aerodynamic trickery has been worth it.

After speaking recently to a fellow tech analyst, he suggested that Mercedes used DRD as a calibration device to set the wing angles for each circuit, hence why they were using it throughout the year in practice only. Having said this, Ross Brawn told journalists at the back end of last season that they would pursue DRD into 2014 as they believe it is worth the investment. Lotus and Sauber subsequently reduced the amount of time they spent on the device after the summer break and have yet to confirm any future plans.

DRD has become one of the strangest technical developments in Formula 1 history. Teams continue to dabble with the device, so there must be a lot of potential locked up within it. This can only be justified by Sauber putting resource into it – they can’t afford to simply have a play with it, unlike the top teams.

Coming back in full circle, the image Lotus released today suggests that DRD has not been fully integrated with its 2014 chassis. It is still possible to use the device, as the inlets can be built into the engine cover. There is a high chance we will see it appear once more this season. However, I can’t help but feel that this could be a sign of the conclusion of millions of pounds worth of research and development and with it one of the most innovative design prospects that did not quite succeed.

Images courtesy of Octane Photography

William Tyson

William Tyson

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.

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