Power Corrupts
Text by Jake Venter
Source: This article was taken from the April 2011 issue of Car Magazine
If its latest rulebook is anything to go by, Formula One is straying further from the cutting edge – and relying on gimmicks to spice up the competition
Has Formula One racing become a mere TV spectacular on par with WWE Smackdown and so-called reality shows? Some might argue it has because the sport no longer represents the pinnacle of automotive engineering. There are now so many restrictions on what can be done that engineers are forced to spend most of their time circumventing rules designed to limit the performance of cars. One could say the teams are in a perpetual technological cat and mouse game with the FIA (F1’s governing body)! As soon as one team gains a technological advantage it has to be penalised. The official viewpoint comes over clearly in the new rule concerning weight distribution. To coincide with the 2011 change to Pirelli tyres, this is fixed within the range 45,5 to 46,7 per cent front and 53,3 to 54,4 per cent rear to ensure that one team alone doesn’t strike it lucky and stumble on the perfect set-up. The phrase in italics is taken from the official F1 website and shows an attitude that can only result in diminishing the technical relevance of F1 racing.
Lotus Renault is one of the teams that have come up with a unique approach to 2011. It will run forward-exit exhausts.
Worst of all is the restriction on engine development, which means new materials and problems inherent to pushing up rev limits can only be tackled in the artificial environment of a dynamometer cell.
Be that as it may, just for the record, the new season starts with a number of rule changes. The more important ones are:
Banned:
- The moveable front wing that was used in 2010.
- The F-ducts that allowed a driver to cover a hole in the cockpit to alter the airflow over the rear wing. Any system or device that uses driver movement as a means of altering the aerodynamic characteristics of the car is prohibited.
- Double diffusers. The tightened regulations on stepped floors mean that double diffusers are now more difficult to arrange.
Allowed:
Adjustable rear wings
A driver may now adjust the rear wing of his car from the cockpit, altering its angle of incidence to one of two set values. It is hoped that this will boost overtaking.
The adjustment must be electronically controlled so that it can be used at any time during practice and qualifying, but during a race it may only be activated when a driver is less than one second behind another car and then only at pre-determined sections of the track. Once the driver brakes for a corner, the (non compulsory) system must be deactivated.
KERS
The kinetic energy recovery system (KERS) has been reintroduced after a year’s absence, but it is also not compulsory. Last year the system was not used by mutual agreement, resulting in an increase in fuel tank size. Now that KERS is back, some redesign will have to take place to accommodate the battery packs.
The most popular KERS is similar to the system used on production car hybrids. A generator driven by the rear wheels absorbs some of the energy wasted during braking to charge a battery pack. The generator changes into an electric motor the instant the driver presses a power button, making the energy in the battery available at the driven wheels.
The regulations allow a maximum of 60 kW and limit the storage capacity to 400 kilojoules. This means the power button can be used for up to 6,67 seconds per lap, all at once or at different points. It is estimated that lap times may benefit by as much as 0,4 of a second. This system weighs about 35 kg, complete with batteries, and Formula One cars must weigh at least 640 kg, including the driver. Cars are usually designed to weigh considerably less, so that ballast can be added where necessary to improve handling. With a KERS system on board, there is less scope for ballast placement and less freedom to change weight distribution.
Using a flywheel to capture the kinetic energy from the wheels has been tried, but it is expected that most teams will use the electric system.
J-dampers
These items are not new, but are worth considering because their workings are still a mystery to most people. They were introduced amid a great deal of secrecy by McLaren in early-2005. Renault became aware of the system when Phil Mackereth joined them from McLaren and the design featured in the subsequent Formula One spying scandal. At present most teams are using the device.
The J-damper was invented by Professor Malcolm Smith of Cambridge University in 2003, and he called it an “inerter” because it uses inertia rather than friction to dampen movement. Smith cooperated with McLaren in 2004 to develop a system for Fl. The design chosen uses a small flywheel mounted on bearings inside a housing. A rod attached to a left suspension member is threaded through the flywheel and the housing is attached to the right suspension member in such a way that suspension movement causes the flywheel to rotate and absorb or give out kinetic energy, depending on whether the wheels are moving up (bounce) or down (jounce).
These units are mounted front and rear to dampen vertical movement but are inoperative when the body rolls. They’re supposed to be worth about 0,2 seconds per lap.
The power button can be used for up to 6,67 seconds per lap
Changed:
Reduced tyre allocation
Bridgestone has withdrawn from Formula One after 13 years and Pirelli now takes over as sole supplier. Drivers will only get 11 sets of dry-weather tyres instead of 14 per race weekend. They will receive two prime sets and one optional set for the first and second practice sessions, but must return one set after each session. They will then get eight sets for the rest of the weekend but one set of each specification must be returned after the third practice session.
Both specifications of dry-weather tyres must be used during a dry race and if a driver fails to do so he will be excluded from the results. If a driver cannot use both types because the race has been suspended, 30 seconds will be added to his race time.
Unchanged:
Engines
Engine specifications were frozen for the 2007 season to keep development costs to a minimum, with engines used in the 2006 Japanese GP as benchmarks. These specification engines were used for the 2007 and 2008 seasons, with revs limited to 19 000. For 2009 and 2010, the maximum revs were reduced to 18 000.
Each driver was allowed only eight engines per season. Design changes to improve reliability were allowed, but Mercedes-Benz and Renault (perhaps others as well) effected changes that also increased power output. Cosworth re-entered the Formula One engine scene in 2010. Engines for the 2011 season are unchanged, and are being supplied to the various teams by Renault, Mercedes, Ferrari and Cosworth.
These engines have to be naturally-aspirated 90-degree 2,4-litre V8s, with a bore of 98 mm and a stroke of 37,9 mm.
They must have two circular inlet and two circular outlet valves per cylinder. Variable-geometry manifolds and variable valve timing are banned. Each cylinder may have only one spark plug and one fuel injector. Engine components must be made from materials similar to those being used in production engines.
Information regarding the power output is kept secret, but engines are likely to produce over 500 kW , at 18 000 r/min and about 275 N.m of torque at around 16 000 r/min. This means the kilowatts per litre figure would be just over 200 and the torque per litre about 115. This equates to a mean effective pressure (BMEP) on the pistons of 14,5 bar. The average piston speed – which depends on the stroke length as well as the maximum revs, and is an indicator for the stress in the engine – is 24 m/s at 18 000 r/min.
Production engines from most of the top sportscar manufacturers can just about equal the above average piston speed, although at far lower maximum revs, as well as the torque per litre. However, the power per litre of Formula One engines is far higher than production engines because of the very high revs.
Forced-induction passenger car engines exceed the racing engine’s torque per litre and average piston pressures quite easily, showing just how much stress modern turbocharged engines have to cope with.
The stress at 18 000 r/min can be gauged from the fact that at a fraction past top-dead-centre on the intake stroke, the crankshaft pulls the piston and connecting rods down with an acceleration of almost 8 500 g. This means the 0,250 kg piston feels like it weighs 0,250 x 8 500 = 2 125 kg or 2,125 tons as far as the crankshaft is concerned. This is equivalent to hanging eight Range Rovers onto the crankshaft of a V8 Formula One engine! At these loads, the connecting rod stretches enough to make a significant difference to the compression ratio when compared with the static compression ratio.
Historically, the most striking feature of Formula One engines is their inability to improve on the 14 bar BMEP values generated by the famous 1967 Cosworth DFV V8. Since the BMEP depends to a large extent on the breathing ability of an engine, this is equivalent to saying that the breathing ability of racing engines has reached an upper limit.
The future:
For 2013, the FIA intends to change the engine formula to 1,6-litre straight fours with the maximum revs limited to 12 000. Energy recovery systems will be compulsory, of course – and I will, undoubtedly, be suitably underwhelmed.
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