Formula 1 Keels
From no keel to single keel, twin and V keels and finally back to no Keels.
© Craig Scarborough
If aerodynamics were not a concern, the nose\footwell section of the monocoque would be as low as possible in order to keep the centre gravity height as low as possible. But ever since teams started to raise the noses and then the footwells of the cars in the early nineties, the design of this area has been compromised heavily in favour of aerodynamics.
This is because the Front wing needs to be more efficient, and hence teams want to make full use of the width of the wing and not have it interrupted by the nose. More recently it is where the front wing sends it flow that is important. For the wing to be effective it needs to send its trail into a clear space. Previously the footwell was in the way and the noses were raised ever higher to clear any obstructions.
The front of an F1 car is strictly regulated by the FIA, the cockpit opening and the size of the front\dash bulkheads is mandated. It is these rules that have lead to the middle part of the car being so uniform around the grid. What has been left to the designers is where to place these bulkheads in respect to the cockpit opening and a minimum length restriction. By raising the front bulkhead (A-A) more space is provided under the footwell, if the dash bulkhead (B-B) is also raised then even more space is provided. Some teams have raised the both the bulkheads above the 550mm high cockpit, necessitating a step in front of the cockpit opening. While for 2006 some teams have lowered both bulkheads to make the underside of the chassis more parallel to the ground. The Centre of Gravity penalty for all these designs is made up for in ballast placed low down in the car.
But raising the footwell creates problems for the front suspension; the two wishbones are set at a specific angle (geometry) in order to improve the cars mechanical grip and handling. As the nose was raised the mounting of the lower wishbone to the chassis was no longer possible. Teams started to make the underside of the chassis into a V shape meet the wishbones inboard pivots. As the nose rose higher still the inboard mounts joined at the centre line and the slight “V” shaping became more pronounced and became known as a single keel.
In 2005 Renault introduced a revised keel arrangement, dubbed the V keel, this was effectively a single keel layout but the usual solid shape of the keel was altered for a hollow “bracket” this freed up some airflow and also the keels shape was more structurally efficient, making it lighter.
In 2001 the FIA mandated that the front wings ride height was raised to reduce downforce, the rules did allow for a lower section of the wing across the middle 50cm span. This made the middle of the front much more critical and the position of the single keel placed directly behind was an obstruction that the aerodynamicists sought to avoid. It was at first Sauber that raced Twin keels, based on an idea from the Harvey Postlethwaite designed Honda test car. This set up split the single keel into two (twin) keels, which now moved to the outside edge of the monocoque, leaving the middle of the noses underside free from obstruction. How ever this was only one solution and many teams made cars just as effective with a single keel during this period. One of the problems with twin keels was their structural efficiency. That is to say their stiffness for a given weight, it is often quoted that twin keels were less effective because they flex, this is an intuitive but naive observations. F1 teams know the level of stiffness they required from the monocoque and as a result twin keel cars were simply made with more metal or carbon reinforcement, this gave the required stiffness but added weight. Through out 2001-2004 the argument between single and twin keels was about even. Arrows, Jordan, Williams, McLaren, Sauber all ran twin keel set ups, but slowly each stepped away from the concept, weight and simplicity were the reasons and aerodynamic developments also made the wing more efficient at its outer tips to make up for the downforce initially lost from the higher ride height. Some teams ran vertical twin keels (Sauber, Arrows, Jordan) while McLaren used splayed keels to widen the area under the nose, Jordan and Williams also adopted this format for their twin keel set ups
Also in 2005 the FIA once again raised the front wings outer tips and again the emphasis on the obstruction behind the wing was a higher priority. McLaren were quick to pick up on this requirement and having already run very drooped front wishbones they were able to devise a better layout for the front of the car. As keels were only ever required to match the needs of the front suspension geometry and the raised footwell. As the footwell height was an aerodynamic necessity it has only been the altering of the suspension geometry that has allowed the keel to be dispensed with. By making the two (upper and lower) closer together and making them point more steeply upwards from the wheel towards the chassis they have been able once again to mate the wishbones directly to the chassis. This is a stiffer lighter set up and also creates the free space under the nose. Dubbed the “Zero keel” layout, although I prefer to call it “Keel-less” as should this be adopted by all teams the term keel will be redundant.
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