Many of us, I am sure, would love to press a button and have an extra 80 horsepower kick in. I know I would in my Honda Civic. However, an F1 car is a different animal, so will this power boost mean an unassailable advantage to those who have it?
How KERS Works
An electric generator is attached to the crankshaft. This generator doubles as an electric motor later. Under braking and while the wheels turn the crankshaft, this device harvests some of the kinetic energy, turning it into electricity, up to a 400 Kilojoules limit. This electricity passes through a control unit and into a battery pack.
There it waits like a caged animal until it is unleashed at the press of a button. The reverse process now takes place. Electricity surges from the battery through the control unit to give a jolt of 80 horsepower (60 kilowatts) to the motor/generator and back to the crankshaft (as described in this BBC interview of the McLaren team in 2009).
Quantifying the Advantage
F1 regulations set limits on a KERS system. Article 5.2.3 states “The maximum power, in or out, of any KERS must not exceed 60 kW. Energy released from the KERS may not exceed 400 kJ in any one lap. Measurements will be taken at the connection to the rear wheel drivetrain.” (See the official F1 website).
In addition Article 5.2.4 states “The amount of stored energy in any KERS may not be increased whilst the car is stationary during a race pit stop. Release of power from any such system must remain under the complete control of the driver at all times the car is on the track.”
Crunching those numbers means a maximum 6.67 second burst of 80 horsepower to release all that energy. The driver can also choose to release it in shorter bursts. It all shakes down to an overall lap-time reduction of about 0.3 seconds. That amount of time can be crucial in F1 and can cover quite a few cars in qualifying.
If there is enough grip with the track surface, the extra power is useful. KERS will have a greater effect on acceleration at low speeds than at high speeds. Of course traction is dependent on the tyres and on the amount of downforce available, which will depend on the aerodynamic capability of the car, and on the properties of the particular race circuit.
The Disadvantages
KERS won't make any difference to the top speed, because the crankshaft rotational speed is limited to 18,000 rpm. As most of the teams will be using it, the advantages in most cases will come down to the quality and reliability of the individual systems.
There are also issues under braking where KERS alters the balance of the car. The electrodynamic braking effect of the system is greater at higher crankshaft speeds. This means that the braking force on the rear wheels will lessen as the speed decreases, and the friction braking system will have to compensate. We may see a lot of twitchy braking as the balance moves towards the front wheels.
Critics and Spectators
As this BBC discussion shows, there are criticisms of the reintroduction of KERS, on the grounds of cost and unfairness to the smaller teams among other reasons. Whatever our view is of KERS, it is likely to produce some exciting moments, maybe even race-changing moments, and for most F1 teams it will remain the must-have accessory for 2011 at least.
Sources
Bruce Bowden - Bruce Bowden writes about science and other topics. His book Strange Harbinger is a science fiction mixture of comedy and drama.
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