Over the past three races Mercedes have produced a near “B” spec car, with a new gearboxrear suspension, new sidepods and a new nose. The cars specification was also altered to suit the low drag demands of Montreal with a shallower rear wing and modified front wing.
Every year High Power Media, who publish ‘Race Engine Technology’ (RET) Magazine, produce a number of magazine format Race Technology Reports. Covering F1, Moto-GP, Nascar, Drag racing and 24-hour racing.
Just out is the current F1 Race Technology issue, covering Technical subjects from 2011 and 2012.
Every year at low Drag circuits some teams will try a more radical way to reduce downforce and drag from their rear wing. It’s rare these solutions get to race, as teams invariable end up running more downforce than the barest minimum these special wings provide. This year Williams bucked that trend and have an all new low drag rear wing. Williams have gone for an opposite strategy to last years (http://scarbsf1.wordpress.com/2011/06/11/renault-wiliams-complex-low-drag-wings-for-canada/) and have created the wings downforce towards the tips of the wing and not the centre.
Having revised their exhaust position throughout the opening races, Ferrari had found some stability with their Mugello package. However, for the Canadian GP the team brought what will probably be their definitive set up for the year. Like most teams Ferrari have followed McLaren’s practice of a exiting the exhaust pipe out of the side and housing it within a duct to help the flow to be redirected inwards and downwards towards the diffuser footplate. This solution diffusers from McLaren’s in several areas, but like other teams who have followed the McLaren exhaust set up, the differences are a pragmatic approach to save having to redesign the entire sidepod package. The team have also brought revised brake ducts, turning vanes and a Canada specific wing package to Montreal.
Its been announced today that the FIA have issued a Technical Directive clarifying the issue that emerged over the Monaco weekend around the Red Bull floor hole. This TD-13 outlines that the area 650mm outboard of the cars centreline cannot now exploit fully enclosed holes. As a result Red Bull will have to change the floor design before the next race, the Canadian GP. Although their design has now been deemed to be illegal retrospectively, so they are allowed to keep their results from the three races in which the design has been raced, including the win in Monaco.
Having introduced a “tyre squirt” slot into the floor ahead of the rear tyres at the Bahrain GP, Red Bull had completed two complete GPs before rival teams raised questions about its legality. On the morning of the Monaco GP, several teams started a discussion regarding the slots legality, as it did not follow the practice of Sauber or Ferrari in linking the hole to the edge of the floor. No formal protest was made, but the Technical Working Group (TWG) wanted the rules around holes in the floor clarified.
With the switch to Pirelli tyres, their rear tyre construction has needed a lot of care in managing degradation. This drop in tyre performance happens when the tyres drop out of their operating temperature window, and this can come from the tyres running too hot or too cold. As the preceding RenaultSport article explains managing rear temperature takes a lot of effort and understanding. McLaren have been active in understanding this problem and over the past year have developed an innovative method of controlling tyre temperature via its relationship with Brake temperatures. It’s come to light in the past two races McLaren have an adjustable brake duct set up and this can have an impact on tyre temperature.
F1 carbon brake disk temperatures can peak at over 1000-degrees centigrade. The discs being 278mm diameter inside a 305mm wheel means that there is little space between the two and heat inevitably passes from the disc into the magnesium alloy wheel. In previously years this was avoided to try to reduce heat conducting into the tyre, but McLaren have found a way to harness this.
By altering the flow of heated air coming from the periphery of the brake disc, the amount of heat passed into the wheel and tyre and can be altered. Already teams tune brake cooling with different inlets scoops, but these tend to stay fixed from qualifying onwards (wet races excepted). If the team want to alter brake and thus tyre temperatures during the race then normally there’s no path open to them. However McLaren have fitted an adjustable window in the rear brake ducts. A mechanic can adjust this in the pits to tune the brake and tyre temperature to suit conditions. Depending on the wording of the Parc Fermé rule, this could also be altered on the grid as one of the areas allowed to be changed is brake cooling blankings.
To do this McLaren have altered their brake cooling design from most other teams. More typically the round brake drum cooling ducts exit the brake flow through the rounded outer face of the duct; this passes out through the wheel spokes. McLaren’s brake discs vent their through openings in the outside of the brake drum, with its outer face closed off from the disc. So all the heated brake flow passes between the duct and the wheel before exiting through the wheel. To accommodate this flow, McLaren’s wheel spoke arrangement has been altered. The Enkei wheel features 29 drillings around the face of the rim, with the more conventional spokes positioned inside these drillings. Brake flow is directed through these drillings and relatively little passes through ten holes between the main spokes. With this set up the heated brake flow has far more contact with the wheel, both as it passes to wards the spokes and even the spokes themselves have more surface area to absorb heat from the brake flow.
Normally teams tune the brake cooling via the inlet, taping it over or changing to a different sized inlet scoop. With the McLaren system the inlet scoop remains largely the same, but brake cooling is tuned via a threaded adjuster (Yellow in the following diagrams) moving a flap to either open or close the openings in the brake drum. This is analogous to the cars engine cooling, the inlet tends to remain the same and the outlet area is tuned for optimum cooling. A larger than required duct will create extra drag, but I suspect the operating window the adjustable duct is within quite a small range. Probably smaller range than switching to the next size brake duct inlet.
When the flap closes the opening, more heat is retained within the duct for hotter brakes, but cooler tyres.
Conversely opening the flap to expose more duct exit area, brakes run cooler and more heat is passed into the tyre.
Also, see these images comparing the adjustable brake ducts of Hamiltons car (right) and the unadjustable ones on Buttons (left). via Russell Batchelor XPB.cc. The silver coated section inside the brake duct on the right, is the adjustable part. This semi cylindrical panel winds in to open up more cooling outlet area.
We have seen the adjusters fitted to the rear brakes in Bahrain, but they’ve reportedly been on the car since China and F1 insiders tell me they were used even last year. I’m also told the front brakes are adjustable too, but I’ve seen no evidence for this. One thing is clear, these are quoted as secret devices, but most rival F1 engineers know about them!
I understand the brake ducts can be adjusted from a single point near the fuel filler flap, so I presume cables (Grey in the preceding diagrams) run from the threaded adjuster back to the middle of the car. At a pitstop the mechanic can adjust the brakes with a tool accordingly.
See this picture from the Spanish GP (via F1talks.pl) shows the adjustment in operation. Cables from each of the adjusters meet at the fuel flller flap and the mechanic, who is usually there to hold the car steady and clear out the airbox, can adjust the ducts with a pre-agreed number of turns on the hand tool in the adjuster. As the adjustment is done via a mechanic it is a legal change to set up, allowed once the race starts, but not during qualifying or whilst the car is in Parc Fermé. When the car is stationery at a pitstop, the system is not considered moveable aero.
Changing the brake ducting will alter the amount of brake cooling, opening the duct will allow more heat to escape and reduce brake disc temperatures and vice versa with closing the ducts. Adjusting the rear brake temperature may be the sole reason for this season. With changing tyre balance and KERS usage the rear brakes have been prone to overheating. But the more likely benefit is the effect of the brake heat altering tyre temperature. As the brake heat passes through the smaller set of drillings in the wheel, this has a greater surface area than the more usual 8-10 spoke wheel; this allows more heat to transfer into the wheel. Heating the wheel will transfer heat into the tyre; this will be useful when the driver is struggling for tyre temperature. The contrary is reducing the heat transfer into the wheel to reduce tyre temperature when the driver is struggling with heat related degradation.
Of other teams are able with their current wheel and duct arrangement to alter tyre temperatures via heat radiated from the brakes, then this will be an easy modification to make to the car. However many other F1 Engineers suggest that they find little effect of brake temperatures altering tyre temperature, making the solution unattractive to them. So it’s not clear if this is a must have solution or other teams are able to tune tyre temperatures with more conventional means. As yet I have not seen any other team run these types of brake ducts.
Sauber have proven to be one of the more progressive teams with aero development this year. The team’s have played with several different approaches to aero and exhaust positioning over the opening months of the year.
Now Sauber have produced their fourth sidepod iteration and surprisingly it is a McLaren style exhaust outlet. This goes away from the path they forged with the ramped downwash sidepod. Aiding the new exhaust position is a revised vane over the top of the sidepod.
The team also ran a revised front wing. I will cover this development in a separate post.
Sauber launched their car with a simple sidepod (above); this almost looked like a Red Bull RB5 set up, with the top exit exhaust aimed generally over the rear bodywork. This simple initial attempt was probably just for the launch pictures.
As soon after, the definitive Melbourne spec exhaust was tested. This sported a distinctive ramped section, which created a downwash that drove the top exit exiting exhaust flow downwards, then the ramped tail of the diffuser encouraged the flow to follow the sidepods line down towards the rear tyrediffuser. This mix of downwash and coanda effect all but reproduced the EBD effect used in 2011. As the exhaust flow was directed along the bodywork, it appears to be more accurate way of directing exhaust flow towards the diffuser. However the effect lacks a path for the sidepods undercut airflow to pass through. Red Bulls Melbourne spec (V2.0) exhaust attempted to cure this with the cross over tunnel.
To aid the downwash flow over the sidepod Sauber added a horizontal vane over the front section of sidepod. This front 15cm of sidepod is free of the bodywork restrictions of the main sidepod volume. The vane points the airflow downwards, to drive greater flow over the exhaust exit. In isolation this vane actually creates lift, as is common with F1 aero this counter intuitive solution creates more global downforce because of its downstream effect, than the small loss in downforce its creates on its own.
In practice for subsequent races Sauber tried a third iteration of the exhaust, still with a top exit, but the exhaust faired-in and blow out through scalloped slot, presumably to better direct the airflow. Using similar interpretations of the exhaustbodywork rules as McLaren exploited with their side exiting exhaust. This V3 set up wasn’t raced and will probably never race, with this fourth version now seen in testing.
The V4 sidepod discards the philosophy of the firth three completely, instead the sidepod is shorter and the coke bottle area forms a much tighter waist. Protruding from the flank of the sidepod the exhaust sits inside a small bulged fairing. This fairing mimics the McLaren with the open topped channel cut in to it, to allow the downwash to redirect the exhaust flow. The channel probably also provides a small degree of coanda effect in bending the exhaust flow downwards, but far less than with the earlier sidepod designs.
Exhaust flow exiting the duct now passes openly towards the tyrediffuser intersection. With the coke bottle area now free of the ramped section, the undercut sidepod flow can pass towards the centre of the diffuser to use the energy in the flow to drive some downforce from the trailing edge gurney and starter motor slot.
With the change in sidepod profile and the exhaust exiting more sideways the through the top, the downwash vane has also been altered. Rather than a horizontal vane, the vanes curved around the frontal of the sidepod, to create the depression over the revised exhaust outlet position.
Sahara Force India ran a new front end in testing, with some of the distinctive features from the launch car dropped. The new set up is aimed redirecting the flow along the edges of the nose towards the floors lower leading edge. The new package consists of; a revised nose tip, front wing pylons and different turning vanes.
The team also ran a revised sidepod package with McLaren style exhaust outlets. I will cover this development in a separate post.
From the cars launch and through the first four races, the nose tip sported a hammer-head style twin camera set up. Now the cameras have relocated to further back along the nose and the nose tip now forms a more aesthetically pleasing rounded shape. Although neutral in aero section, the camera pods are placed in a position where their shape will interact with the airflow to create some aero benefit downstream on the car.
Below this the pylons mounting the front wing have been extended and form a linger vane like shape. This was something FIF1 have worked with a lot over the past few seasons. Using this shape as part of the cars aero set up for different speeddownforce circuits. Typically longer pylons for higher downforce tracks and smaller pylons for places like Monza. Although the vanes may well create some low pressure behind the neutral front wing centre section to create load at the front axle, I expect they are more for directing the airflow along the y250 axis. This is a longitudinal line along the edge of the chassis, 250mm from the cars centre line. This is effectively as far outboard aero devices are allowed and hence where teams tend to focus on vane development. Creating different flow structures along this axis, helps creates the airflow distribution at the floors lower leading edge which is critical to diffuser efficiency.
Along similar line are the new turning vanes, on the launch car these were the popular “L” shaped hanging vanes (pictured above), mounted beneath the nose cone. Now they are a pair of curved vanes under the front suspension, a similar solution to SauberRenault and adopted by Red Bull last year. Again similar to these teams there is a small split in the vane to induce a stronger vortex effect along the y250 axis.
On Day3 of today’s Mugello test, Ferrari appeared with a major update to their sidepodexhaust configuration. Although at this stage it’s not clear if this set up is Ferraris definitive exhaust solution going forwards, or merely another interim set up.
What’s clear is Ferrari continue to follow their own path for exhaust and cooling flow. With the main cooling outlets being via chimneys exiting from the flank of the sidepod, a solution popularly termed the “Acer ducts”, due to the presence of the sponsor’s logo on the launch spec bodywork. With the launch car the exhaust exited through the rear exit of the ducts, and latterly the exhaust was moved to prevent overheating rear tyres and the duct cut away to allow more inboard location of the exhausts tailpipe.
Now the “Acer” ducts are brought more inwards and the exhaust exits over the top of the duct, periscope style. This suggests the exhaust is not being aimed at the floor at all, simply along the centre of the top bodywork towards the beam wing and the winglet mounted atop it. This would be less effective at creating downforce, but would be less sensitive to throttle position and have less of an effect on the rear tyre temperatures.
The floor and top body mouldings appear to new and quite large sections. This also suggests that the bodywork is going to change. Often with interim bodywork the panels are smaller to allow different shaped sections to be added. However the black heat shield panel around the exhaust is removable and may allow a switch to a McLaren style open-topped duct exit.
The continued presence of the vortex generator near the mirrors suggests some downwash effect is still being created, although the current spec is not really making use of it.
I will update this post as the test develops
McLaren have long since followed their own path in aero development. Certainly since 2009 the car has increasingly diverged from other team’s aero concepts and the 2012 MP4-27 is no different. However the current car has a clear lineage in some of the design solutions and the whole front end is an evolution of recent cars.
Their first car to the current aero regulations in 2009 sported a conventional nose, front wing and cascades.
The car that was launched in 2010 had a very different front end. The drooped nosed of the MP4-24 was gone replaced by a more horizontal and shallower nose cone. Beneath this was fitted large aero device, I term a “snow plough”, Williams had run a similar solution in 2009.
From a horizontal leading edge positioned between the front wing mounting pylons, the snow ploughs surface splits into left and right sections and eventually forms a pair vertical vanes protruding below the nose. This creates a “V” section mid way along its length and the twist of the airflow along with the pressure differential between the upperlower surfaces creates vortices trailing from the rear of the vanes. This is an aggressive solution compared to the simpler turning vanes other teams use. This device probably creates some downforce in its own right, but I suspect the primary purpose is to direct the strong vortices along the Y250 axis, to drive a better airflow towards the floors lower leading edge.
Later in 2010 after a series of different iterations of endplate and cascade design, the wing substantially changed for Singapore GP. The main plane was effectively split into two; a section ahead of the front tyres and a section inboard of that. The intersection between the sections formed an upright for the main cascade winglet. While the less aggressive inboard wing span gains a simple “r” shaped vane.
McLaren continued the 2010 design of snowplough nosecone and split front wing into 2011 with the MP4-26. Again later in the year, the wing was simplified for the Indian GP with similar endplates and cascades, but the complex split shape wing profile was changed to be straight across its width.
Again this format was brought forward to the launch and initial test version of the 2012 MP4-27. Only in the last days of Barcelona testing did the revised front end appear. Gone was the snowplough and the straight wing profile. In their place was a simpler nose cone and a pair of vanes dropping vertically from the nose. While the more complex split wing profile was reintroduced. With EBDs less powerful this year, teams are finding downforce levels are lower. We could conclude that the snowplough and straighter wing arrangement were better for downforce, so the new simpler arrangement may be a more efficient way of producing less downforce.
The other change in China was the deletion of the slots in the small cascade winglet. The slots would have reduced the strength of the vortex produced by the winglet, removing the slots will have increased them. This change will be made in order to direct a stronger airflow around the inside face of the front wheel.
As the team get to grips with the new exhaust regulations and start to develop more downforce, potentially some of these solutions could return. So any reappearance will tell us a story of development and aero load figures in 2012.