Lotus E20 Drag Reduction Device

There’re quite a few comprehensive analysis on Lotus E20 Drag Reduction Device, however I’m trying here to put on a simple explanation to the system so that everyone can understand.

Lotus DRD, we call it DRD instead of DDRS as this system is nothing related to DRS, although the function is the same – reducing drag. It’s completely passively controlled by car speed to achieve drag reduction. The benefit of isolating from DRS (compared to the Mercedes DDRS system) is that it’s not limited use to the specific DRS area on the circuits and does not have a delay over activation – the Mercedes DDRS needs to go all the way from the rear wing to the front wing, causing delay.

The whole structure of this device looks like this:

Source: ScarbsF1

It basically contains two inlets – the airbox and the ‘ears’ and two outlets – the periscope/L duct and the mini diffuser/monkey seat. I’m not going through the internal ducting as it’s purely speculation going into this area, for which I’m not very sure about.


Besides the normal airbox inlet, Lotus places two additional inlets along each side of it like two ears. Those ears help directing excess flow into the rear part, thus reducing turbulence from air spillage and help generating more downforce when DRD is not activated. In addition, it’s suspected that the air that goes into the ears and airbox subsequently flows into different route through internal ducting to the rear outlets. However, as I’ve mentioned, I’m not going into detail on this.

Source: Sutton Image

Airbox and ‘Ears’ On Lotus E20 Airbox


There are two ways that the air can goes out of the car, either through the mini diffuser or the L duct. The path that the air goes depends on the speed, or air pressure.In a relatively low speed, i.e. off throttle condition, air mainly goes through the mini diffuser since higher pressure is required to push air through the narrow L duct. As the critical speed reaches, air can pass into the L duct then exit through 2 slots on each side of the duct, causing stall on the main plain of rear wing.

The structure of both the mini diffuser and the L duct is quite tricky if you look into the detail.

For the mini diffuser, there’s actually a small internal part inside which aids downforce generation when device is not activated.

Lotus E20 Mini Diffuser/ Monkey Seat Detail

The L duct is very narrow to ensure that it’s only activated when a certain speed is reached, those tiny air exiting slots make huge difference to the airflow pattern  – cause flow separation to stall the wing. The FlowViz picture can clearly show this effect:


Lotus E20 Flow Viz Interpretation

Basically Flow Visualization paint is a special liquid sprayed to the car in order to study airflow on the surface. When the car runs, flow pattern is recorded as the paint redistribute due to the air goes over. So as can be seen in the Lotus Flow Viz illustration, there’s a V-shape pattern beneath the main rear plain right in the middle at the exit of the L duct, indicating flow separation, i.e. drag reduction. Also those 3-5 cm slots are shown clearly once zooming in to this area:

Lotus E20 L duct/ Periscope Slots Detail

The device need to be adjusted from race to race to modify the speed of activation, mainly by modifying the cross section of the mini diffuser and the L duct.

So as Mercedes came up with the intelligent DDRS which is activated by DRS, Lotus brought out a entirely passive system DRD. However, neither of the systems has given distinctive advantage to their cars. Regardless of that, it’s still a very clever idea that may inspire engineers for more innovation.


Monza Low Downforce Setup

There is no circuit in F1 that looks simpler than Monza, a typical circuit dominated by long straights. In response to this, downforce is not that favourable here, on the contrary, low downforce setup aiming to reduce drag is the key to win the race.

Front Wing

Front wing is not often changed significantly from race to race as it is the part that determines downstream flow, therefore affecting the design of all following parts. However, for Monza, most teams have adjust their front wing by removing cascades, lower down AoA or reducing chord length.

McLaren has removed all the outer cascades and replaced their 2-section upper flap with one single upper flap.

Source: Formula1.com

McLaren Front Wing Change from Spa to Monza

Source: Sutton Image

McLaren Front Wing in Monza

Another noticeable change on front wing is from Ferrari, who has removed all the small upper cascades and made several changes to the flaps and endplates profile.

Source: Formula1.com

Ferrari Front Wing Comparison from Spa to Monza

Rear Wing

The rear wing design is closely related to exhaust/cooling, sidepod and rear diffuser. Teams have different adjustments based on their cars. Major methods to reduce downforce/drag in Monza includes slimming rear wings, introducing V-shape profile and use gurney flap on diffusers.

With Massa hitting 3rd in qualifying and Alonso finishing on podium from 10th start, Ferrari proved their speed in Monza. They modified the beam wing with a V-cut profile and slimmed outer span, fit gurneys along the trailing edge of the diffuser, and quite uniquely, added flaps above and below the diffuser. The V-cut supplies the car with enough downforce at corners with low downforce setup for straights. Use of gurneys and additional flaps help regulating the flow, correspondingly reducing drag.

farrari monza rear design
Source: ScarbsF1

Ferrari Rear Design for Monza

Similar to Ferrari, Red Bull also used a V-shaped beam wing, in combination with a rear wing of very small AoA. They’re among the teams that suffer the most from the ban of exhaust blown diffuser this year and quite obviously still haven’t found a ideal design for their underbody rear part. In Monza, they’ve also added an additional tier to the diffuser gurneys, though that didn’t seem to give them clear benefit.

Red Bull V-shaped Beam Wing

Source: Sutton Image

Additional Tier on RB8 Diffuser Gurney

As the low downforce rear wing has clearly given Button huge advantage in Spa, McLaren is quite happy using this setup for both cars in Monza with a few modifications to further reduce drag. Instead of slimming the wing as other teams, McLaren cleverly introduced a curved profile at the tip of their beam wing to smooth air flow.

Source: ScarbsF1

McLaren Rear Design for Monza – Note Curved Tips on Beam Wing

Lotus has drawn wide attention because of their so-called DDRS system – It’s still quite confusing how people call this device though. Anyway we’re not seeing it until Singapore since Monza is not a preferable circuit for this system. In Monza, Lotus runs on the shortest chord rear wing, which makes it look quite tiny from behind.

Source: F1 Technical

Lotus Rear Design for Monza

Check this post from ScrabsF1 for more detailed analysis of rear end design based on each car relating exhaust/cooling/sidepod to rear wing assembly.

McLaren Spa Updates

With a dominant win from Jenson Button in Spa, McLaren has demonstrated their aerodynamic excellence after two successional win. It’s shame that Lewis was crashed out at the beginning of race, leaving us curious about how those two differently set-up cars would actually do in the race. Instead of seeing huge impact from DDRS, what drew attention is actually McLaren’s rear wing adjustment and sidepod airflow conditioner, while their DDRS remains a mystery.

High Downforce vs Low Downforce – Hamilton’s Deleted Tweets

The hottest topic outside the track is definitely Hamilton’s tweets during the weekend. Three of them get delated in two days, among those ghost tweets, the most famous one is the telemetry chart of the two McLaren cars.

Source: F1Technical

McLaren Overlaid Telemetry Chart

It looks a bit completed as there are lots of information merged into one single chart. However, telemetry chart is simple to read when you know which property each line represents. As a common approach of F1 data collection and analysis, a telemetry chart in fact can’t leak out too much serious information. Here is an example of a telemetry chart from 2010, which as an coincidence, is from Lewis Hamilton again. From the top to the bottom, properties plotted on the y-axis are speed, engine revolutions/gear, throttle/brake usage, lateral/longitudinal G force.

Telemetry chart in Bahrain 2010

As we can guess in Lewis’ leaking out chart, the most fluctuated lines represent his speed and Jenson’s. It’s obvious that on straights, Lewis’ car accelerates slower and has lower top speed compared to Jenson’s. Basically Jenson’s car has a low downforce configuration while Lewis get a high downforce one. The picture below combines Lewis’ and Jenson’s car during qualifying – with lower angle of attack, Jenson’s car has reduced downforce and drag, which gives him huge advantage on straights.

Source: Sutton Image

Comparison between Jenson’s and Lewis’ Car During Qualifying

However, this doesn’t mean lower downforce is always better on high speed circuits like Spa – downforce at severe corners should always be considered; weather condition has vast impact as well. Nevertheless, McLaren has clearly found the best compromise this weekend for Jenson.

McLaren New Sidepod Airflow Conditioner

The most evident change on MP4-27 in Spa is these airflow conditioners added on top of the sidepods.

McLaren Sidepod Airflow Conditioner

Now the airflow conditioner is connected to the cockpit and runs all the way over the sidepod. It’s expected to further regulating flow around the sidepod and towards the exhaust channel. In Hungry before the summer break, McLaren was using 3 fins on top of the sidepod as vortex generator to improve airflow.

McLaren Sidepod in Hungry

These fins would help smoothing the air by generating controlled vortex flow:

Effect of Vortex Generator

Although vortex generator is a good idea, McLaren seems to find those L-shaped covers over the sidepod working better in controlling the air.

Curiosities – Flexible Front Wing? DDRS?

An interesting picture of McLaren front wing in Spa indicates that it’s flattened during the race:

McLaren Flattened Front Wing

There was suspicion from ScarbsF1 that McLaren use flexible front wing to achieve better aero balance last year in Valencia – McLaren European GP Wing Movement. However although the suspicion was broadly argued, this picture still arise doubts on McLaren tricking on their front wing. Theoretically flexible front wing uses a joint rather than a rigid structure that allows the wing to tilt slightly backwards at high speed. The reduction of angle of attack would reduce front downforce/drag so that it corresponds to the reduction of rear downforce when DRS is activated. Because of the increasing limitation on rear part design, McLaren has actually focused a lot on the front part this season, as reflected in their lifted nosecone earlier this season.

Source: F1Technical

McLaren Nosecone Update

Although the so-called McLaren DDRS was buzzing before the race, there was no clear technical sources leaking out regarding this part. Some says there’re strange bumps on the rear endplates, which could mount in tubes like the Mercedes DDRS. However we still need to wait for more information to make judgement.

Bumps in McLaren Endplate

Besides McLaren, most teams have noticeable updates in Spa. There were more information of Lotus DDRS leaking out though it was not used in this race and is expected to be used in Japan Grand Prix. Also closed cockpit looks favourable in the future considering the huge crash in this race. These topics are hopefully covered in my future posts.

DRS? DDRS?? – Pre Spa Excitement

F1 is finally back this weekend to Spa, a favourite circuit to many F1 fans and drivers. Lots of curiosity and excitement arised over the cars’ upgrades after the summer break. It is expected that McLaren would use their new DDRS design in Spa, together with Lotus further exploring their DDRS after the last two races before summer break. So huge focus is on DDRS again, which was introduced by Mercedes at the beginning of the season…


Let’s have a look at DRS first. DRS stands for Drag Reduction System. It was introduced to F1 in 2011 season, basically referring to adjustable flap on the rear wing. It’s a fairly simple system, as clearly illustrated in this 2011 video from Red Bull on both KERS and DRS. Jump to 1:24 for the DRS part.

KERS and DRS explanation

So when DRS is activated, the flap on the rear wing get flattened and therefore opens a slot at the rear wing, which produces a better streamlined shape of the car and consequently reduces both the downforce and the drag. Note that with the reduction of drag always comes along the sacrifice of downforce although the degree of reduction can be different. However, at long straights, less downforce is needed. By activating DRS, the car can boost 10 to 15 km/h extra top speed. DRS is allowed all the way in qualifying, but in races, only through overtaking zone when the a car is within 1 second to the front car after 2 laps is finished.


As the words suggests, DDRS = DRS+DRS, a double drag reduction system. It was primarily developed by Mercedes, as one of the biggest innovations of 2012 season. In addition to the DRS system, Mercedes introduced a passive system which activates when DRS is open. It basically feeds the air from the rear wing and guide it through the cockpit to the front wing, therefore forms another DRS at the front part of the car.

Construction of Mercedes DDRS

The video below shows clearly how the air flows through the car:

Mercedes DDRS System

DDRS is very good for further reduction of drag on the straights, it more importantly gives the car good aero balance. In F1, aero balance is very important to guarantee stability – the ratio of downforce produced on the front and rear wing should be roughly the same as the car front and rear weight distribution. DRS is normally used on straights as it would be dangerous to use at corners with an unbalanced car, whereas DDRS has a potential to be used in less curved corners, also allowing the driver to activate it earlier after corners before going onto straights.

How does Mercedes DDRS work? – History and Analysis

We might need to go through some history here. It’s widely acknowledged that the design of DDRS is inspired by the F duct of McLaren in 2010, which is a great application of passive ducting system fighting against those rules set by FIA.

A bit off topic.. if you look through the innovations in f1 technology history, what engineers have been doing can be summarised as ‘finding the flaws of F1 rules’! 2009, double diffuser; 2010, F duct; 2011, exhaust blown diffuser – all banned after one season of usage. However, the idea of passive ducting system has been inspiring engineers since 2008, being modified every year based on the rules.

For your information on F duct, as a genesis of DDRS:

How does F duct work

So the experience from F ducts tells us:

    • Slots on the wing can be used to disturb air flow, therefore stall the wing to reduce drag (Note: stall of F1 wings means a reduction of downforce and drag rather than lose of all lift force on airplane wings)
    • It’s beneficial ducting the air
    • Passive system is a clever choice to gain downforce/ reduce drag without violating the rule

These are taken into Mercedes DDRS design, in which the air is guided from the rear wing through the channel along the car, exit at the front and cause front wing stall – A clever passive system which only operates when DRS is activated.

Question still exists on how the air flows exactly out of the slots. Generally speaking, engineers add slots to the wing either to generate more downforce or to reduce drag depending on the direction of the slot. In this case, we’re focusing on reducing drag, in which the direction of air flow should disturb natural flow, causing flow separation in order to stall the wing.

It’s suspected that besides the F duct idea, Mercedes DDRS is also related to their W duct design in 2011 on their front wing, which guide the air into the nose and feed it into different parts of the front wing

W duct of Mercedes W02 in 2011

The point here is that by blowing air underneath the front wing, you’d be able to increase the maximum angle of attack allowed for the car to run. Basically engineers increase the angle of attack to increase downforce until a critical angle of attack is reached, in which case the wing stalls and no more downforce can be generated. The blown air has a positive effect on increasing this angle, therefore allow higher downforce to be generated. So the slot here in W duct aims to increase downforce. It’s uncertain whether this now works along with Mercedes DDRS system so that more downforce is generated when DRS is inactive while stall occurs when DRS is active – considering aero balance, there is actually not too much downforce required on the front wing. Nevertheless, opening slots on the front wing could be an inspiration for Mercedes when developing their DDRS this year.

However, the use of DDRS system didn’t make Mercedes the fastest car in F1. It seems to work well in qualifying while not showing any benefit in Sunday races. The effect of stalling the front wing is quite controversial, even though the advantage of aero balance, top speed increase and passive activation still looks really appealing.

Lotus Passive Pylon Duct

After Mercedes, Lotus brought out a completely different DDRS design that instead of reducing drag at the front wing, it further reduces drag at the rear. Since FIA has clearly banned F duct design that uses slots at rear wing, Lotus places the slot at the connection between the rear wing and the engine. This would also cause wing stall and is passively activated by DRS beyond a certain air speed. As this system is only tested in the last two races, no consensus is reached yet on how it works exactly. However I’ll keep updates on this system.

Speculation from SomersF1: http://somersf1.blogspot.co.uk/2012/08/lotus-e20-passive-f-duct-system.html

Source: Sutton Images (www.suttonimages.com)

FloViz Interpretation of Lotus Passive Pylon Duct

Future of DDRS?

I’m very curious on what kind of DDRS system McLaren is going to use. It’s expected and should be completely different from the Mercedes and Lotus systems. DDRS system, especially Mercedes one, is actually very difficult to copy since it requires the change of whole monocoque. Like all the previous innovations, DDRS is likely to be banned in 2013 F1 season although the official announcement has not come out yet. Let’s see what can happen to DDRS in the rest of 2012.

Spa is in fact one of the most ideal circuit for DRS application – capable of reducing lap time by 1.2s! So get excited for the race this weekend!