# Formula One glossary

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A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Racing line
This is the optimum line around a race circuit, therefore in theory it is the fastest way around a circuit. For a lone corner this is usually a wide entrance, followed by a defined ‘apex’ which is near the middle of the corner on the inside, and a wide exit to allow all the power to be used. It is the straightest line through a corner.
Rack
A gear with teeth spaced along a straight line and suitable for producing straight-line motion (instead of in a circle).
It is used to convert a rotary motion (the pinion) to a linear motion (the rack).
A type of tire construction which has the main carcass plies or cords which run at right angles to the bead and parallel to the radius. By itself, this construction is very weak because when the bias angle is smaller, the structure is stiff. However, the radial tire has a very large bias angle. In order to strengthen the tire, a belt surrounds the circumference. This belt is made of low-angle plies (usually about 15 degrees). In this way, the tread area is stiff and the sidewall are flexible. In this way they can act independently of each other.
A device that cools the liquid in the cooling system by allowing it to circulate through a series of water channels, which are exposed to air ducts. F1 radiators are located in the sidepods just after the air intake holes.
A fan to provide cooling air toward the radiator. Such a fan can be electrically driven or coupled directly to the engine. Formula One cars lack a radiator fan an rely solely on driving air on the radiators to cool the engine down.
Rain tire
Treaded tire used in wet or damp conditions, otherwise susceptible to abnormal wear. Tread pattern designed disperse water at 26 litres per second at 185mph
Rake
Describes the ride height of a racecar where the front end is lower than the rear. A raked underbody can create downforce as it forms a venturi with the ground surface.
Rebound
In shock absorbers, a rebound adjustment is a change to the dampening of the shock on the expansion stroke. Without rebound dampening, the car would tend to bounce as it passes over bumps on the track. Rebound adjustments can also affect how the weight of the car shifts around during braking, acceleration and cornering.
Reconnaissance lap
A lap completed when drivers leave the pits to assemble on the grid for the start. If a driver decides to do several, they must divert through the pit lane as the grid will be crowded with team personnel.
Red flag
A solid red flag is used to stop the race immediately. Generally races are stopped for bad accidents or weather. Occasionally, a multiple car pileup will halt a race. Wreckers and fire marshals clear the track of cars, debris and fluids. Alternatively, rain makes the surface of the race track dangerous. Once NASCAR officials authorize the race to start again, a green flag resumes the race.
Renault
Car menufacturer that ran their own f1 team from 1977 to 1985 achieving great successen thanks to its turbo engines. Renault returned to the series as an engine supplier to Williams in 1989 and went on to dominate with the team until 1994. Renault purchased the Benetton team for \$120 million in 2000 and return as a works team in 2002.
Retirement
Retirement is usually the result of an accident or mechanical failure on the car, either way it means the car and driver are out of the race and will not be scoring any points for the team.
Reynolds number (Re)
In fluid mechanics, the Reynolds number (Re) is a dimensionless number that gives a measure of the ratio of inertial forces to viscous forces and consequently quantifies the relative importance of these two types of forces for given flow conditions[2].

${Re} = \frac{inertial forces}{viscous forces}$

Typically different Reynolds numbers characterize different flow regimes. Laminar flow for instance occurs at low Reynolds numbers; turbulent flow occurs at high Reynolds numbers and is dominated by inertial forces, which tend to produce chaotic eddies, vortices and other flow instabilities.
Rhodium
A silver-white noble metal in the platinum family; atomic number 45, atomic weight 102.905; used in thermocouples and, together with other platinum metals, as a catalyst in catalytic converters.
Ride height
The distance between the bottom of the car and the ground is called the ride height, this is controlled in the regulations by the use of the ‘plank’.
Rising rate suspension
A suspension system where the spring rate increases when the wheels move further into jounce. This action can be accomplished by configuring the geometric shape of the suspension, by using springs which change tension as they are compressed, or by using two or more springs with rubber stops. The purpose of a rising-rate suspension is to maintain consistent ride and handling characteristics under a variety of situations: loaded or unloaded, straight roads or curves, and smooth roads or bumpy.
Roll rate
The roll rate in racing is the speed that a vehicle changes its roll attitude. As roll is the rotation around the longitudinal axis of a car, agressive drivers that make sharp turn-ins into corners will experience slightly higher roll rates than fluid drivers that gently rotate the steering wheel.
Rotary engine
An internal combustion engine which is not of a reciprocating (piston) engine design. There is no true crankshaft, although the power-take-off shaft is sometimes called the crankshaft. It is stationary or fixed in that it simply spins in place. The central rotor turns in one direction only and yet produces the required intake, compression, firing and exhaust strokes. Because it uses rotary motion instead of reciprocating motion, the rotary engine has better balance and less vibration than piston engines. Two common rotary engines are the gas turbine and the Wankel engine.
Run-flat tire
A tire which can run for a certain length of time without air in it. In the inflated state, conventional tubeless tires perform the task of containing air and rolling. Once deflation occurs, the tire bead becomes dislodged from the rim bead seat and slides into the rim well. As a result of friction, the tire will become distorted and the rim may plough into the road, leading to loss of control and potentially resulting in an accident. Run-flat tires are designed to operate effectively with or without air, providing acceptable handling qualities when deflated, and good handling qualities when inflated. Run-flat tires have not been used so far in F1 and seem unlikely because of the weight disadvantages that come with it.