Monaco: What Happened to Buttons McLaren on the Grid

Fans blow through tubing into a duct, with an optional dry ice tray, which is secured into the sidepod with a foam block

At the start of the Monaco Race, McLaren had a rare engine failure. This was not a problem with the engine itself, but caused by a procedural problem on the grid.
Before setting off for the grid the car is warmed up in the garage and the driver often completes several laps, cutting through the pit lane before finally parking on the grid. By this time the car is fully up to temperature and needs fans to keep the car cool. In the case of the engines radiators and oil coolers, this takes the form of fans inserted into the sidepod inlets. Fans pass cooling air through the radiator cores to cool the engines fluids.
For McLaren their sidepod fans comprise several parts, an external fan which feeds into convoluted tubing to a carbon fibre duct, this has the option of a tray of frozen nitrogen being inserted into it to further reduce temperatures. This then is inserted into a rigid foam block that is squeezed tightly into the sidepod inlet itself. Other teams have electrical fans fitted into similar carbon mouldings, these are all in one piece and when removed nothing can be left behind.
What happened to McLaren in Monaco, and this was partly shown by the FIA TV feed, that the mechanics withdrew the ducts and tubing, but on one side the foam black was left stuffed in the sidepod inlet. This was obviously missed by the mechanics, but was brought to their attention by the BBC TV pit lane reporter Ted Kravitz. By then it was too late and the car had to complete the formation lap and start the race with the block still in. The team were obviously anxious, but the block does have a hole through it, so some cooling airflow was getting through. With the safety car deployed on the opening lap and the pit lane closed, Button had no choice but to circulate a low speed, with the engines temperature slowly rising until steam could be seen spewing from the sidepod.
Although this was a rare error, as the car has these fans fitted when it pits during testing and free practice. One still wonders if McLaren will revert to a one piece design or tighten up the grid procedure to prevent another similar situation arising at future races.

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Monaco Set up: the misconception of wheelbase

Monaco’s layout presents unique demands to the teams. As we are all aware, it’s all about slow and tight turns, thus devoid of any long straight or fast turns. Other tracks have low speed turns (Hungary) and there are other tight turns (La source at Spa). Monaco combines all of these and adds the issue of public roads. Complete with; camber, bumps and kerbs, plus the ever present Armco barriers lining the trackside.
 
Thus Monaco requires an exclusive set up to cope with these demands. It’s well known that teams run maximum downforce here; the drag that this inefficient aero set up brings bears no penalty as there are no straights to speak of.  With the addition of aero devices limited now with the 2009 rules, teams cannot add the plethora of add on winglets and flaps to add downforce.  This year a few teams will run add-on winglets in the 15cm free zone in the middle of the rear wing, but little else aside from maxed out wings and gurney tabs will be used.  Ferrari have added a small winglet to the tail of their shark fin engine cover this weekend for a little extra downforce. Additionally a floor and diffuser that work well at higher ride heights will be beneficial, although teams do not run Monaco specific floors. Obviously to cope with crowned road and bumps, teams run their cars at higher ride heights around the principality. Added to this softer springs and roll bars will induce more wheel travel and see the aero move through a greater range of attitudes than normal. For Monaco the resulting aero penalty is offset by the greater mechanical grip. 
 
Due to the low average speed, Monaco is much more about mechanical grip than aero; this is an area where misconceptions exist.  Wheelbase, although its a fundamental fact that shorter vehicles have tighter turning circles, in F1 terms wheelbase account for very little at Monaco.  With wheelbases over three metres, the difference in team’s wheelbases is just a few percent and not enough to have a primary advantage over the other factors differentiating the cars.  Long wheelbase cars have won at Monaco and in testing teams and drivers have never found wheelbase a key factor through tight turns.
 
Frank Dernie quoted me a couple of perfect examples; “when Brabham were concerned about their 1983 long wheelbase car around Monaco because it was around 12″ longer than the previous car, Nelson said he did not notice it at all” and pulling directly from his experience when at the start of the Eighties Williams were testing the FW07 six wheeler (a standard FW07 with an extra rear axle).  “The Williams 6-wheeler obviously had an effective long wheelbase and one of the first things we tried, before committing to the project, was a tight circuit test at Croix-en-Ternois to make sure it was not a disaster. Jacques Lafitte said he forgot he was driving the six wheeler after a few laps.” 
Mercedes GP are bringing their previous front suspension to Monaco.  This results in the car resorting to its previous short wheelbase set up.  This is not aimed at creating a shorter more nimble car, but simply not being enough long wheelbase wishbones available to the team.  Unfortunately for Mercedes this will push weight forwards in the car, which is counter productive at a track where rear tyre traction is critical.
 

 

So while wheelbase is not a primary factor in rounding tight turns, then what is?  Steering lock accounts for most of the solution, only Loews at Monaco (the tightest turn in F1) and La Source are turns where the driver has to turn the wheel beyond half a lock.  Drivers sometimes having to remove one hand from the wheel, to get enough clearance for their crossed arms.  If the front wheels can turn enough then the car will get around a tight turn, of course a longer wheelbase car will need slightly more lock for the same turn a short wheelbase car.  To allow the front wheels to steer enough a few mechanical alterations are required.  Firstly the steering racks can be altered with a different ratio to the rack and pinion.  But more commonly the outboard end of the track rod is brought closer to the uprights kingpin (steering) axis, resulting in more ‘steer’ for the same rack displacement.  This can bring an extra 5-degrees of steering angle.  To allow a power steering system to have a longer stroke, the teams need to alter the pistons that assist the rack in moving, by also making them longer.  Then at the outboard end of the wishbone, the pivot bearing should have enough freedom to steer the wheel through the required angle, but clearance between the wheel and the wishbone often requires the wishbones to be altered.  This is normally just a notch moulded in the rear leg of the upper wishbone.  Teams do also fit more robust wishbones for brushing the Armco, as well as tougher drive shafts.  Although the latter is as much about accelerating over bumpy surfaces, than the side thrust from a wheel touching the barrier. 

So who ever goes well at this weekends GP, will be as a result of a mechanical set up and downforce that are matched to the tyres. How long their wheelbase is not going to be the deciding factor. Although who actually wins may be as much down to luck as any set up parameter!

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