This week we’re going to take a look at the detail around a Formula 1 driver’s head and the location of his helmet, which is critical to the efficiency of the airbox.
Starting with the airbox intake, the area required needs to be able to pass enough mass airflow to allow the engine to produce maximum torque when the driver is applying full throttle. This would normally be around 75-80mph, when the chance of wheelspin is minimised.
If the inlet is too small, the car will not accelerate as fast as it should. If sized correctly to achieve this initial aim, the engine will not be able to use all the airflow that’s presented to it at the other end of the speed range, say 200mph.
If it’s working as it should at this speed, the airbox will create a positive pressure of around 25-30 millibars, which will help the engine performance.
Any excess airflow that the engine can’t use spills around the sides of the airbox. Consequently, this makes the detail design of this area very complicated – if this spillage does not stay attached to the engine cover sides, the turbulence created by this wayward flow will hurt the performance of the rear wing.
So, the two criteria for the design of an efficient airbox intake are making it big enough to get maximum acceleration, and small enough to minimise the spillage at high speed.
The area underneath McLaren’s intake is a big undercut © sutton-images.com
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Taking this requirement a step further, in the past when the driver closed the throttle to slow for a corner, the airbox spillage became a lot worse. If the airflow attachment on the sides of the engine cover was not good, the performance of the rear wing would be compromised – not something the driver wants under braking or on corner entry.
Step forward the blown diffuser. Hot or cold blowing allows the engine to work like an air pump, moving this airflow through and out of the exhausts. This reduces the potential turbulent airflow creating negative performance on the rear wing.
Hot blowing only means that the exhaust gasses leave the exhaust exit with more energy, but in reality does not increase the mass airflow.
So How do the different teams detail this area?
Let’s start with McLaren. The MP4-26 has a heavily undercut area below the airbox intake. This allows the airflow coming off the driver’s helmet to run along the top of the headrest area and into a small cooling duct that’s underneath the airbox intake.
The limpet-style cooling duct on the engine cover will also pick up the airflow that spills out of the airbox intake at high speed. The effect of this cooling will be increased at high speed and the airflow to the rear wing will not be compromised quite as much.
Flow-vis paint shows how the air is travelling at speed © sutton-images.com
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Having this style of undercut makes the rollover design a bit more complicated, as the vertical loads required to pass the FIA tests are in excess of 12 tons.
Getting the sizing correct for this style of intake is quite difficult and circuit testing is really the only way to try to understand how the airflow is reacting when the driver is on and off the throttle.
Here McLaren is using an airflow visualisation paint. This is applied as a liquid just prior to the car leaving the pits, and will then move along the surface at speed, showing the direction of airflow.
When the car comes back into the pits the paint will have dried and the engineers can try to make some sense out of it all. They might not be able to do anything immediately, but information gathered will influence future designs.
Most cars have very similar intake designs, with the undercut to allow for the airflow coming off the driver’s helmet. The sides of the headrest are defined in the technical regulations, so there’s not much room for manoeuvre in this area.Keeping it as small as the regulations allow and with a tidy leading edge blending into the chassis profile is just about as much as can be done.
Virgin airbox 2011 © sutton-images.com
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As can be seen, Virgin doesn’t have the limpet-style cooling duct. It doesn’t require as much cooling as McLaren as it’s not running KERS; however, a cooling duct like the one on the McLaren uses can be beneficial to manage the airflow at high speed.
Lotus and Force India have gone a slightly different route in that they have a central spike-style rollover barb, with the airbox intake split into two inlets.
The rollover bar design for this type of concept is easier and as such should be lighter, but good quality airflow on internal surfaces of the twin intakes will create a few more headaches.
If the flow attachment is not good in the inner airbox surfaces, this will lead to internal airflow separation which can lose engine performance very quickly.
Lotus splits its air intake into two with a spike-like structure © sutton-images.com
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With the engine cover removed (below) we can see the snorkel-style airbox. The design detail for this component has changed over the last few years: it used to be a fairly quickly expanding throat going from the intake and developing into a large plenum chamber, but now it’s longer with much less expansion going to the centre of a smaller plenum chamber.
This gives better and more equal airflow to all of the eight trumpets within this area, improving overall engine performance and especially fuel consumption as it reduces fuel transfer between cylinders.
As I have said many times, a Formula 1 car is one complete aerodynamic surface; to get maximum circuit performance, every part of the car has to work together as one. Unfortunately, there is always something that gets compromised.
As can be seen below , with the driver neatly cocooned in the headrest area and his head as low as possible to help with the airflow to the airbox, and rear wing and the chassis as high as possible at the front to allow for better airflow coming off the front wing to the underfloor, his vision of what’s close to him is compromised.
This is fine if he only has to look 20-25 metres down the road, which in reality, if things are going to plan, is where the driver will be looking.
But get into a close, heated battle as we have seen so many times this year – like Hamilton and Massa in Singapore – and is it any wonder we’ve seen so many drivers losing their front wings against the rear tyre of another car.
A major part of the wing is in front of the front tyre and this combined with the low seating position means they just can’t see any part of their own front wing.
Also, if you looked closely at Kamui Kobayashi when he had his kerb-hopping escapade during qualifying in Singapore, he was suffering the same fate.
Yes, he went in too quickly, but he couldn’t see the kerbs from his seating position. You could see him straining against his seatbelts to try to get a better view.
F1 chassis are high at the front, restricting vision © sutton-images.com
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I am sure this situation even led to Schumacher going over the back of Perez. Surely this is a safety concern. For next year the FIA could instigate a regulation that requires the seated driver to read a number placed on the track at a sensible distance in front of the car – say five metres. This could also be placed anywhere across the width of the car.
If that test was put in place, and that stupid front wing was to be shortened, we would have a lot closer racing and a lot fewer incidents – or am I just making things too simple?
Wouldn’t it be great if we could only turn the clock back? The problem is that most of the drivers of today wouldn’t know what to do with a gear stick.