Hockenheim represents a demanding blend of both high top speed and good cornering grip. Unless you’re in a Mercedes it is very difficult to balance the car for this type of circuit. Red Bull had phenomenal pace in the final, tight sector but where half a second down in the middle relative the main competition. Williams by contrast – who have a slippery car in a straight line – had a solid first and middle sector, as proved during the latter stages of the race when Valtteri Bottas held off Lewis Hamilton.
As far as upgrades go there were a few finer details across all teams, but it was McLaren who stood out the most this weekend.
To date, McLaren introduced one of the biggest technical revolutions of the season in Germany as they fast-tracked a rear wing that was actually due to run in Hungary.
Along with changes to the endplates (which I will come onto later), you will notice the serrated profile along the leading edge of the top flap and the trailing edge of the main plane, forming a ‘zip’ effect. My interpretation is that the two edges do not interact with eachother directly as their jobs are quite different. Let me explain…
Let’s start with what these sinuous edges are. They are called tubercles and their background is quite interesting.
Whilst this is not a new aerodynamic development in an overall context, tubercles are – as far as I’m aware – new to F1. There have been previous iterations of the concept used in LMP racing and some gurney tab designs with the unique serrated effect in the past, but nothing to this new level that McLaren have produced.
Research has been conducted over the past few decades on the effects of humpback whale tubercles on their large fins. Conclusions were made about their extraordinary maneuverability in water considering their size, with the tubercles on the leading edge of their fins allowing them to turn in a tighter circle. This was because the tubercles created less drag through the water.
When DRS is activated, the top flap is opened by about -10 degrees to the horizontal – pretty flat. This means that the oncoming airflow is hitting the leading edge of the flap almost square in the face. Whilst the reduction in drag from the system mainly comes from the stalling of the main plane and air rushing through the large gap left by the open flap, the flap itself can still cause some drag. McLaren have addressed this issue.
You can see that on the leading edge of the above aerofoil that the high pressure on the leading edge (represented as red in this CFD image) is disbanded across the tubercles, whereas on a normal straight edge the line would be quite a solid colour. This alone is proof that there is a reduction in drag. According to appliedfluids.com, an aerofoil with tubercles at +10 degrees has 10.9% less drag than one without tubercles.
However the tubercles also function well when the top flap is closed, when DRS is inactive. Studies have shown that an aerofoil shape with tubercles on the leading edge can decrease the sensitivity of the wing, allowing an increase in Angle of Attack (AoA) by as much as 40% without risk of stall. McLaren will be running with pretty high AoA anyway, but they have a little more freedom in terms of setup now.
The sensitivity of the wing is decrease because the air is funneled along the wing’s profile, generating lower pressures at (what I’d like to call) ‘hotspots’. The hotspots have such low pressure that it remains attached for a longer period of time, thus increasing downforce. Whilst there are still some stagnant points on the tops of each tubercle, the pressure difference sets up vortices which further improve airflow attachment.
So that’s a decrease in drag with DRS open, a greater setup choice for the driver and more enhanced downforce: win-win-win!
The trailing edge tubercles on the main plane, however, behave slightly differently. They still set up vortices, but they are projected along the backside of the top flap. I think they amplify the ones shedded off the top flap to keep airflow firmly attached across a range of speeds, hence why the tubercles on the flap and main plane appear to line up with eachother.
Other than the tubercles, the endplates also received some treatment. Two sets of arced, staggered fins aligned the both the upwashing area of the wing and the slatted section along the base of the endplate. These arced fins create small vortices and a low pressure area behind. In the case of the fins arcing the slatted region, the low pressure will help pull more airflow through the slats to increase the outwash effect at the rear of the car. Likewise with the upper set, although they enhance the upwash effect of the rear wing. The more air being pulled through at a faster rate, the higher level of downforce you can induce.
The front wing endplate also received a small tweak, with an extra lip on the endplate fence’s trailing edge to push airflow further around the front tyre.
Interestingly, McLaren also opted to nominate new gear ratios for the remainder of the season. Teams only get one opportunity to do this during the season and the changes could compliment the new low-drag rear wing.
Williams had another impressive weekend, as they continue to capitalise on arguably the second quickest car this year.
Earlier this year we saw a slotted shark fin engine cover, and this returned for Germany. The fin features about 15 louvres along each side and they bleed off high temperature air built up beneath the bodywork. This is more efficient than opening up the rear bodywork, as it provides extra cooling whilst maintaining a slim rear end.
The Renault power unit is quite sensitive to charge air temperature – the temperature of the air drawn in by the turbo’s compressor and back into the engine. For this reason, Renault have put an emphasis on getting maximum radiator area for the intercoolers to lower the charge air temperature as much as possible, gaining as much power as possible as a result.
Lotus have attempted to tackle the problem by repackaging some of the internal cooling elements – such as the ERS radiators – to make space for larger radiators that cool the water in the intercoolers. As a result, the team have had to look at other cooling options for other components on the car.
A pair of inlets were added just beneath the roll hoop behind the driver’s head. It is unclear as to what they are specifically cooling but I would imagine that it is a small radiator for the battery, that sits directly beneath this area of the car along the floor.
Pastor Maldonado also ran a modified front wing endplate, which featured a singular and rather sculpted vane rather than the previously split layout.
Sebastian Vettel and Daniel Ricciardo diverged on setup options for qualifying (and therefore the race), as each driver chose a different rear aero configuration.
Vettel went for a higher downforce setup which included a deeper rear wing with a higher AoA and additional Monkey Seat above the exhaust. This setup also included the swan-neck central pylon introduced at Silverstone.
Ricciardo on the other hand went for a shallower rear wing and no Monkey Seat, plus the older style central pylon that attaches at the base of the wing’s main plane. This probably shows that Ricciardo is happier with a more unstable rear end on his RB10, with the added benefit of a bit extra top speed over his teammate.
As seen in testing two weeks ago, Red Bull brought this tweaked front wing. The inner cascade winglet’s miniature endplate has been removed in favour of extending each of the two element’s tips upwards. The vane further back has had its own endplate added to it, curving aggressively outwards of the front tyre. These small changes are designed to manage airflow around the front tyre rather than produce more downforce.
Thanks for reading this piece. Unfortunately I won’t be covering the Hungarain GP because I am on holiday over this weekend, although I should be able to get something up once I’m back. Apologies for the inevitable delay. If you would like to find out about the causes of Lewis Hamilton’s brake failure during qualifying, visit this piece I did for Richland F1 here.