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RE: Scarbs blog - maripi - 02-02-2013
http://scarbsf1.com/blog1/2013/01/30/analysis-2013-f1-rules-and-trends/
With far reaching regulation changes coming onto the sport in 2014, the 2013 season is likely to be a year of consolidation, as few changes have been are written into this year’s rule book. So teams will be expected to optimise their designs from last year, correcting mistakes and adopting some of the better ideas of their rivals.
Some rules will have a small effect of car design and some trends from last year will be more common place. Unusually there have been few leaks or well-founded rumours circulating in the off season. This is probably as teams are expending a huge amount of resources in finding big gains for just one year’s competition, instead focussing on plans for 2014.
Rule changes
I have already covered the key rule changes from the first draft of the 2013 rules in a previous blog post . I so will just cover the other changes written in the final set of published rules for 2013
Tyres
Pirelli have worked with the FIA and the teams to change the tyres for 2013. This will result in a more balanced set of tyres and similar high rates of degradation as we saw at the start of last year. To achieve this Pirelli have completely redesigned the tyre range. They have softened the stiffness of the sidewalls of the tyres, but stiffened the shoulders of the tyres. The softer sidewall will induce more heat in the tyre and generally softer compounds will heat up more quickly, produce more grip, and ultimately degrade quicker than before. The stronger tyre shoulder will help keep the more flexible tyre together during a stint. Teams will be forced by this degradation into more than stop per race, also the pair of compounds at each race will ensure one set of tyres will produce far different lap times to the other (at least 0.5s per lap).
Teams and drivers will have to adapt quickly to the new balance, grip and wear levels, meaning flexibility in the cars set up will be important so some mechanical part of the car will need to have scope for greater adjustability.
SECU
Having run the McLaren Electronics Systems TAG-310B ECU since 2006, teams will have an upgraded ECU to run in 2013. The TAG-320 is the same physical size, but has far greater performance and more interfaces. Although useful, for 2013 this has no real impact on the teams, as the ECU is aimed at supporting the complex powertrains to be introduced in 2014.
Front wing deflection test
It was quite clear several teams were again deflecting the front wing at speed during 2012. Rather than the beam bending we’ve seen in recent years were the wing bows down at the tips when viewed from the front. The flex we saw in 2012 was a twist about the lateral “Y” axis, this was evident when at speed the front wing endplate viewed from side could be seen rotating, such that its trailing edge was closer to the ground than the front. This would reduce downforce and drag produced by the front wing and also reduces drag created by the vortices spilling from the endplate finding a different route around the front tyre. Both these effects would improve straight-line speed and make the car less pointy at high speed.
The new test now allows the FIA to place the 1000n (approx. 100kg) load at any point along a 300mm section of the endplate (at points 675mm and 975mm forward from the front wheel centreline). The endplate must not deflect more than 10mm from this test load. Although this test will reduce the twist seen in 2012, it will not eradicate teams still wanting to deflect the wing for aerodynamic benefit, as the load is still quite far forward on the endplate.
DRS use
Aside from the bans on DRS airflow being use to stall the front and rear wings (as explained in the previous blog post), DRS use is also being controlled during practice and qualifying. No longer will drivers be free to use DRS at any point on the circuit, instead DRS can only be used on the nominated DRS straight\s. Thus Rear wings designed for a smaller DRS effect to allow the wing to be used in fast turns will not be useful anymore. Instead teams will need to focus on a greater DRS effect on top speed.
Front roll structure
One final small change to the rules is the relationship between the front roll structure (the small fin ahead of the cockpit) and the cockpit. Previously the roll hoop had to be 250mm forward of the steering wheel, this made issues for teams will drivers with differing steering wheel positions. Now the rules demand the roll structure is 1050mm in front of the rear of the cockpit making the position the same for all teams and drivers.
Trends
Layout
The cars layout is the length of the major components (monocoque, Fuel tank, engine, gearbox) and their relationship to each other. The net total of these lengths dictates the cars wheelbase. Although oft talked about, wheel base is not a critical design factor. Shorter cars do not intrinsically have better abilities in corners. Instead wheelbase is largely a factor driven by the aerodynamicist’s desire for shape to package the sidepods and turning vanes. Layout is critical in other respects; the fuel tank length, gearbox length and engine position all have an effect of the shape and packaging of the car as well as the weight distribution. Allied to these factors KERS positioning is also critical in deciding the layout of the car.
Most teams are increasingly going for longer gearboxes, this is to allow for the slimmest of rear ends and sidepod shapes. Long gearboxes are associated with shifting the weight bias forwards. As F1 cars have a mandatory and relatively rearward weight bias, other elements in the car design are needed to place weight where it’s needed. Most teams fit their bulky KERS batteries under the fuel tank. This is good for safety and low CofG, but it does create a linger fuel tank, which shifts the engine and gearbox backwards making it hard to package a long slim gearbox. IT also works against a rearwards biased weight distribution. Red Bull has been clever to package their KERS batteries beside and inside the gearbox. This allows a shorter fuel tank; bring the engine forwards and allowing a longer gearbox. The weight of the batteries towards the rear helps meet the mandatory weight distribution. We can expect some teams to rethink their KERS positioning to improve the cars layout.
Nose shape
Although not a primary factor in car performance, a lot of the talk preseason will be about the different nose solutions, teams have opted for this year. The rule change to allow a modesty panel bonded on top of the 2012 stepped nose is of little benefit. Teams can fit this fairing and gain a small aero benefit, but already in 2012 teams were finding other benefits from the odd nose step.
—Stepped nose – as used in 2012
For 2013 many teams will simply opt for the same nose step as in 2012 and won’t waste R&D time on this area. Some teams will fit the thin skinned fairing, to gain a slightly better flow over the nose.
—Nose Fairing – stepped nose covered by the 2013 fairing
In its simplest form the nose fairing will simply fill in the step created by the 2012 rules. In crashes the specially specified carbon fibre fairing will simply disintegrate into 1000’s of pieces on impact. It will offer no safety hazard to drivers.
—Bulged nose – the chin under the nose aids airflow
In 2012 some teams were finding aero benefits from a bulged under chin on the nose cone. These appeared to work with both nose high noses (RBR, Williams and Lotus) and lower noses (Marussia). The chins have been in use since 2009, Williams launched their car with a chin and Force India spent two seasons racing with a chin under the nose until 2012. The chin fairing acts in one of two ways, either to negate the effect of the neutral central wing section or to direct airflow towards the under nose turning vanes. We are likely to see teams vary this design according the track and their own turning vane solutions.
—Slotted nose – top and\or bottom slots reduce boundary layer growth
Two teams found new ways to exploit the nose in 2012, Sauber and Red Bull both created slots in the nose to divert airflow away from the external surfaces of the car. The nose cone and monocoque form some of the longest unbroken surfaces on an F1 car. Being so long these surfaces can build up a thick boundary layer, this is a layer of airflow that sticks to the car, and it can create drag and lead to stalled airflow. The very long and flat noses dictated by the 2012 regulation only worsened this problem, so a slot that sucks the boundary layer of the surface will help general airflow over the car. In Red Bulls case there were two slots only highly visible one above the nose, which formed the driver cooling slot aided airflow over the car, while another slot under the nose fed the FIA timing transponder with cool air and also served to keep the airflow clean under the nose. Sauber ducts a slot form under the nose, to clean up the boundary layer and directed into the area behind the stepped nose to help keep airflow attached in that area. It’s possible that such boundary layer control slots could be adopted despite the 2013 rules allowing more conventional noses.
—Z625 Nose – the fairing can effectively to used to make the nose even higher
One means to circumvent the 2012\2013 nose rules is to use the fairing in a more aggressive way. The nose structure that forms the crash protection must not be higher than 550mm above the floor. However more airflow could be forced under the car for more downforce if the nose were higher. As the fairing is allowed to be as high as 625mm, this could form a new nose tip 75mm higher than the rules intended. With a shorter structure nose cone, the modesty fairing could instead be shaped to form a very high nose for better aerodynamic performance. This is likely to be viewed as marginal on the rules, but the rules do not preclude it.
Front Wing
Front wing design is now near a converged format across the grid. The wings all feature 3-4 profiles with the main working area of the wing in the outboard sections. The flow over the wing diverges and the wing sends a lot of the wake around the front tyres. It’s largely the endplate design that differs. Most teams will form the lower part of the endplate by curving the wing tips down to form the foot plate, then adding vanes to curve the airflow outwards and meet the minimum endplate surface area rules. Both Red Bull and Ferrari adopted this format, but chose to make the vertical endplate more conventional, having one surface stretching across the entire wing length and curving it outwards nearer the tyre. This appears to create a strong more aggressive outwash than the multi vanes endplate seen on all the other cars.
Cascade elements were far smaller in 2012, as the team strived to find more rear downforce from the exhaust blown diffuser area. The trend was towards a simpler winglet attached to the endplate and the inner cascade winglet being replaced with a simpler vane. It will be testament to the team’s ability to claw more downforce from the exhaust\diffuser if we see a return of larger cascade winglets.
Despite the new Deflection test, teams will still employ methods of flexing the wing for some aerodynamic benefit. As already mentioned the test is not placing its load at the rearmost end of the wing so careful structural design can still create a wing that meets the 1000n test, but flexes with the real loads the wing sees at higher speeds. As long as the FIA allow these flexible wing to race and never punish a team for their use, their method of static load tests will continue to fail to prevent this ‘bending’ of the rules. Teams will still use the IMTT excuse ‘It Meets The Test’, even when relatively simple observations from on-board cameras or track side photography prove the wing to be deflecting at speed.
Pullrod Front Suspension
Ferrari opted for a pull rod front suspension in 2012; this was the first iteration of front pullrod since Minardi in 2001. Such is the complex geometry of a modern F1 cars front wishbones, the pullrod installation works from a kinematic point of view. The pullrod moves the rocker\spring\damper as much as a pushrod. The main benefit Ferrari sought was to place the near horizontal pullrod in an ideal aerodynamic path to divert the airflow over the car. Pull rod also offers a tiny CofG benefit, but the top wishbone is more highly stressed over bumps and has to be a slightly stronger construction.
Many teams are rumoured to be running front pull rod this year. This rumour is largely likely to be driven by the mainstream media, which initially criticised Ferrari for the design. Teams could find a benefit in front pull rod, but the 2014 low nose regulations are unlikely to pullrod, so any gain would be for just one year. So it’s likely only well-funded teams have invested the resources for this design for 2013.
As Pull Rod places the inboard suspension lower, Ferrari did have access issues to the torsion bars, dampers, anti roll bar and heave elements. This was made worse when the team switch from nose mounted turning vanes to curved vanes under the chassis. These vanes had to be removed whenever the mechanincs needed access to the suspension. Its possible to switch the spring\damper layout around, by placing the torsion bars upright, as on rear suspension. This would give access to the torsion bars, through the top of the chassis and the dampers would be laid out in a more accessible position. The CofG penalty would be tiny and the car would retain the same aero efficient pull rod position.
Front Brake Ducts
Several teams were already innovating with their front brake ducts in 2011, for 2012 Williams launched with a scoopless brake duct. The usual snorkel projecting out in the airflow to direct cooling air to the brakes was deleted replaced with an aerodynamically more efficient inlet in between the tyre and the brake duct vane. During the season most teams followed this route and we can expect most teams to go with the scoopless brake duct, leaving more room for aerodynamic enhancing vanes and flicks fitted in its place.
Rear Brake Ducts
Ferrari not only went for a scoopless front brake duct in 2012, they are also developed a scoopless rear brake duct. Just as with the front set up, the cooling inlets gets placed in between the projecting brake duct vane and the tyre. This leaves more space for airflow to reach the increasingly complex stack of winglets added inside the rear brake ducts. Not only to these aid the general upwash of airflow behind the car, but also create downforce directly at the wheel.
Wheel retention
With more pit stops required for the new Pirelli tyres teams will seeking further ways to reduce pit stop times. Already 2s has been achieved privately in practice, with the race pit stop time averaging 2.5. Teams are now short of methods to reduce pit stop times further. The longest activity in the stop being the; unbolting, removal and refastening of the wheels. The rules do not mandate wheel nuts, the rules re vague only stating “The wheel must be attached to the car with a single fastener” Thus the means by which the wheel fastener grips the wheel to the axle is free. I can expect some efforts to create a collet type fastener, which undoes without thread. Perhaps its release aided by hydraulics in the axle to eject the collet-fastener and perhaps even eject the wheel when the car stops for a tyre change.
Coanda effect ‘Exhaust blown diffusers’ (EBDs)
—Coanda ramp: A ramp directs the exhaust flow (red), but blocks the coke bottle flow (yellow)
With the tightening of the rules in 2012 to restrict the exhaust effect on the diffuser, teams found several ways to deflect the exhaust towards the diffuser. Unbeknown to us at the time, there was a solution developed by Red Bull. This set up blew the exhaust into the rear brake duct area; the exhaust was then ducted down to the diffusers edge to seal the diffuser as in 2011. This approach was banned before the season started and lead Red Bull to rethink its EBD development. Thus the team launched with an interim conventional periscope exhaust layout, while the tunnel\ramp set up was developed. It was perhaps no surprise that the team on its back foot, struggled to develop their eventual EBD solution.
Meanwhile Sauber found a simple solution, with a ramped sidepod that the exhaust followed down towards the diffuser. This set up employed two aerodynamic effects, Downwash and coanda. Downwash was the effect of the air flowing over the sidepod bending the exhaust plume downwards. Coanda is the effect of the exhaust plume wanting to stick to and follow the ramped sidepod section. Eventually the coanda term has been applied to all blown diffuser solutions, albeit all the solutions use the coanda effect to some extent, the Sauber and latterly Red Bull solutions were the only I’d apply the term coanda to.
—McLaren: Semi Coanda solution
McLaren however had found another solution; they did not want the means of directing the exhaust flow to impact on the flow through the coke bottle section of sidepod. So they had a more open exhaust redirection method. The exhaust exited in a sidepod bulge, the channel inside the bulge ramped down, like the Sauber solution, but is truncated and the exhaust plume was left unguided towards diffusers edge. This allowed the bodywork to be slimmer but the exhaust plume was not directed as accurately as with full coanda ramp. It was the McLaren solution that found favour with other teams and nearly every other team followed this design in 2012.
—Red Bull: Coanda ramp and tunnel solution
Red Bull had a slightly different approach, more akin to Saubers Coanda ramp, but the cross flow problem that McLaren’s design sought to resolve, was answered with a tunnel under the ramp to allow the coke bottle flow to pass under the exhaust flow. Red Bull struggled with the development of the ramp\tunnel set up; at different points the tunnel was closed off, ducted toward the starter motor hole and eventually allowed to exit more freely. In theory the ramp\tunnel set up offer some benefits, but the rules limit the tunnel size to 50mm high, this restrict the flow through the tunnels and perhaps may not present at much benefit as McLaren’s side exit design.
For 2013 teams may well switch between designs, there being no major gain for either design.
—Concept 1: A small ramp catches the exhaust flow and points it towards the diffuser
There is perhaps a halfway house, the ramp idea is appealing but the cross flow issue difficult to solve with the rules as they are. Perhaps the ramp might be split, to allow the exhaust to reattach to be directed toward the diffuser and still allow some crossover flow. Something akin to an open tunnel.
—Concept 2: A ramp sends the exhaust flow under the coke bottle flow
The other idea is the inverse which to pass the exhaust in an open channel, the channel ramped either side to send the cross over flow over the exhausts plumes path. This would still be legal in the eyes of the regulations.
One method to aid the airflow over the sidepod towards the exhaust are vortex generating vanes. Last year most teams adopted a pair of vertical fins, which shed vortices aligned with the exhaust exit. However Sauber and latterly McLaren fitted larger horizontal vanes over the top of the sidepod. These diverted airflow down over the exhaust outlet to increase the downwash effect that bends the exhaust plume downwards. Already we have seen Lotus adopt these vanes and many teams will exploit them regardless of their final exhaust\sidepod solution.
Floor Slots
One feature much argued about last year were the floor slots ahead of the rear tyres. Before EBDs these were to induce a vortex under the diffuser edges to aid sealing t eh diffuser. With EBDs these were redundant, but Ferrari and Sauber revised this idea despite blowing the same area with the exhausts. Red bull also reintroduced their slot, but were force to remove it when they failed to meet the exact wording of the rules. I understand the slot is to return in 2013, as any misdirection of the exhaust plume would be caught by the slot and legally directed under the floor to create the floor sealing vortex all teams are seeking to create with their EBDs.
Gearbox
Gearbox design has been fairly static in recent years, the seamless gear selection mechanisms are common through the pit lane and teams make their gearbox from Cast aluminium, Cast Titanium, or carbon fibre according to the R&D budget. Gearbox weight is not such a critical factor with the mandatory weight distribution. Gearbox length is dictated by the designer preferred car layout and super short gear clusters outlawed by the minimum gear width rules. It’s left largely down to aerodynamics to differentiate between case designs for the teams. Williams found an aero advantage by lowering the gearbox to an extreme level in 2011 (posted here and here) and in 2012 several teams followed a similar but not as aggressive path, by lowering the top of the gearcase, as evidenced by the wishbones mounting on vertical extensions designed in the top of the gearcase. We can expect to see more low line gearcase for 2013, as teams seek to improve flow to the rear beam wing.
Some flexibility in mounting the suspension will be useful with the new tyre constructions, this will be useful both the wishbone to alter geometry and for the inboard suspension (rockers\springs\dampers), so that the team can alter set up to react to testing with the new tyres.
Linked suspension is commonplace, where the front and rear axles are passively hydraulically linked. Mercedes are known to link their suspension diagonally to also manage roll and therefore warp stiffness, independently. This system has been criticized by Mercedes chairman Niki Lauda and may be simplified for 2013.
A trick Red Bull used in 2012 was to combine the rear track rod and wishbone into one component. With the oversized rear leg also fairing in the driveshaft to prevent the rotating shaft upsetting the aerodynamics. Covering the driveshaft with non-structural fairings is not allowed, and this is a practice likely to be adopted by those teams who can get the slightly compromised geometry working for them.
Rear Wing Drag Reduction Devices
As Mercedes and Red Bulls DRS activated Double DRS is effectively banned, tams are now faced with the option of developing passive systems as tested by Lotus and Mercedes in the latter part of the year. Known within lotus as the Device, these have been termed Drag Reduction Devices (DRD) to differentiate them from double DRS (DDRS). These systems do not use the DRS to switch the stalling effect on\off, instead a passive fluid switch is used, with no moving parts, other than the airflow through it, these remain legal. Making the switch from neutral to stalling is difficult, the switch is a gradual changeover, which needs tuning to ensure the stall only occurs above a specific speed in order to retain the rear wing downforce in fast turns. It’s possible that the spillage from the airbox inlet helps change the airflow conditions inside the duct, to switch over. One other issue is that the staling duct under the rear wing will always blow a small amount of air, this will reduce downforce. As will the duct itself which sits below the critical underside of the wing. In 2012 Lotus and Mercedes found the Passive Device to cost as much performance from these problems as it gained in top speed. It’s by no means certain any team will have a really effective DRD. I have no doubt a single duct blowing under the rear wing will create enough of an effect to stall the rear wing for a top speed boost, but Toro Rosso tested with eh double duct arrangement that used two stalling ducts apace 15cm apart. These effectively formed the endplates of the Y75 wing (monkey seat) and would have a greater effect in stalling the flow under the rear wing surface, albeit at an even greater cost in lost downforce from their obstruction to the normal airflow approaching the wing.
RE: Scarbs blog - maripi - 03-02-2013
http://scarbsf1.com/blog1/
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