Formula One glossary

G force

The apparent increase in weight of an object due to gravitational forces. That way, drivers are pushed backwards when accellerating and pushed to the left of the car when turning right and the other way around.

G load

Gravitational loads, expressed in multiples of the force of gravity acting on an object. In a car, these can be felt in acceleration, braking or cornering. Formula One drivers can experience loads of up to 4G.

Gas chromatography

The method used to analyse a fuel’s composition. It breaks down the fuel into its individual components - of which there are over 200 in a Formula One fuel. The results are displayed on a graph known as a ‘fingerprint’ (owing to its individuality) which must be identical to the ‘fingerprint’ of the pre-approved fuel held by the FIA.

Gas turbine

An internal-combustion rotating engine with one main moving part: the rotor with pinwheel-like blades attached. Air is compressed by the first rows of blades and delivered to the combustion chambers, from which the exhaust is directed to pass the remaining blades and to generate the power. Power is extremely smooth due to the absence of explosions and reciprocating parts.

Gasoline

Also known as petrol, gasoline is petroleum based liquid that mostly consists of aliphatic hydrocarbons. Gasoline contains on average 34.8 MJ/l or 9.67 kWh/l and is therefore mostly used as a fuel for combustion engines.

Gear

Wheel-like part with teeth cut into the rim. When one gear meshes with another gear, it causes the second gear to drive the other and in this way transmits power. When the gears are different sizes (different number of teeth on each gear) the mechanical average is changed.

Gear ratio

Ratio of the numbers of teeth on mating gears. Ordinarily the ratio is found by dividing the number of teeth on the larger gear by the number of teeth on the smaller gear or pinion. For example, if the ratio is 2 or “2 to 1”, this usually means that the smaller gear or pinion makes two revolutions to one revolution of the larger mating gear.

Graining

Graining is a phenomenon that happens in relation to tyres when run at their limits. Because of the high stress, tiny bits of rubber can get loose of the tyre thread and lift the tyre slightly off the track surface. As a result, grip is greatly reduced. Graining can be easily solved by careful driving within a few laps, but will obviously have an effect on the driver's pace.
Driving style, track conditions, car set-up, fuel load and the tyre itself all play a role in graining. In essence, the more the tyre moves about on the track surface (ie slides), the more likely graining is.

Gravel trap

A bed of gravel located on the outside of corners, designed for bringing cars that veer of the track to a safe stop.

Grip

The amount of traction a car has at any given point, affecting how easy it is for the driver to keep control through corners.

Ground effect

Type of downforce that is generated by a special formed underside of a race car. Is the most effective like an upside-down aircraft wing, but due to the FIA rules only allowing flat stepped bottoms, current ground effect is generated by the diffuser. This increases the speed of air flowing under the car, and thereby generating a suction effect.
Ground effect cars were introduced by Lotus designed by Colin Chapman. They were equipped with skirt as the sides of the car to lower the air pressure under the car. The problem was that when driving up a kurb, most of that downforce is lost and the car gets very unstable. These care were however forbidden by the FIA as they were deemed unsafe. A flat floor bottom is now obliged.

Gurney flap

The Gurney flap (also known as wickerbill) is a small flat tab which is attached to the trailing edge of a wing. The device is named after the American racing driver, Dan Gurney and it was introduced in the early 70's. The tab's main aim is to further increase the downforce generated by a wing versus relatively small added drag value. Typical applications are sized at about 1-2% of the wing's chord.