Formula One glossary

Damper

A friction device sometimes called a "shock absorber". Used for controlling and damping spring oscillations. The springs actually absorb road shocks; the dampers convert the energy imparted to the springs into thermal energy (by friction), which is dissipated to the atmosphere or the vehicle's chassis. Dampers are distinguishable by the type of friction involved, mechanical or hydraulic, but most modern cars used tubular-shaped hydraulic shock absorbers. Because they affect up and down wheel motions, dampers are an important link in tuning a vehicle's ride and handling. Also see pulsation damper, vibration damper, and harmonic balancer.

Damping

Damping is a highly variable part of car tuning. It's affected by the strength of the shock spring (length and thickness of the wire, plus the number of coils), the size and number of holes in the shock piston, and the viscosity, or weight, of the oil in the shocks. The spring controls how hard the shock compresses, and both the piston and the oil control how quickly the spring pushes the shock to its full length (which can be limited by shock spacers), and so affect the quickness of the shock's return.
Stiffer springs need heavier oil and/or smaller-hole pistons to control the speed of the rebound, and bumpy tracks need lighter oil so the shocks, or dampers, can compress and rebound quickly. Softer damping gives more "stick" on a particular wheel, but makes the car less responsive because the chassis takes longer to reset after a turn, and is also more forgiving to drive. Softer damping also reduces weight transfer at that wheel. Stiffer damping makes handling more responsive, but reduces traction to a particular wheel which can make the car slippery as the chassis snaps back into place after a turn. Stiffer damping also increases weight transfer at that wheel.

Date communications bus

The communications network in a vehicle that allows multiple control modules to communicate with each other. Various protocols determine the speed or baud rate at which information flows over the bus network

DDD

Acronym of double-deck diffuser, a particular design of diffuser introduced in Formula One in 2009 by {Brawn GP}, {Toyota} and {Williams}. The design initially added 15% of downforce over the traditional single level diffuser and consequently led to a court appeal by some other teams who claimed the design was not according to "the spirit of the rules". However, ahead of the Chinese GP, the design was approved and quickly adapted by all competitors.

Delta

Depiction of relative positions of a race car to another car (such as a safety car) on a current lap, or the performance of a single race car on two or more different laps, as displayed on the steering console.

Diesel engine

An internal combustion engine that uses diesel oil for fuel. The true diesel does not use a carburetor or an ignition system (i.e., spark plugs) but injects diesel oil into the cylinders when the piston has compressed the air so tightly that it is hot enough to ignite the diesel fuel without a spark. Because a cold engine cannot ignite the diesel fuel, glow plugs are used to heat the mixture, but they do not provide a spark. Named after Rudolf Diesel (1858-1913), the inventor.

Differential

A set of mechanical gears that eqaulises the power between the left and right drive wheels, particularly when cornering, when the outside wheel travels further than the inside wheel.

Diffuser

An aerodynamic elements close to the floor and in between the rear wheels of a Formula One car. Based on the principle of a venturi channel, a diffuser is designed to speed up airflow under the car by extracting it. As higher flow speeds equals reduced pressure, downforce is generated by the car's floor as a result of the diffuser.

Diffuser gang

Common denominator for the three teams that introduced the double-deck diffuser design (DDD) into Formula One in the 2009 season. The teams are {Brawn GP}, {Williams} and {Toyota}.

Digital fuel injection

(DFI) a GM system, similar to earlier electronic fuel injection system, but with digital microprocessors. Analog inputs from various engine sensors are converted to digital signals before processing. The system is self-monitoring and self-diagnosing. It also has the capabilities of compensating for failed components and remembering intermittent failures

Direct injection

A fuel injection system which is generally used in diesel engines and forces fuel directly into the combustion chamber. It requires very high injection system pressure to overcome the pressure within the combustion chamber

Directional tire

Directional designs are recognized by the grooves in the tread that swipe away in a backward angle from the center of the tread face and rotate in only one direction. A direction of rotation arrow is located on both sidewalls of the tire. Directional tires enhance straight-line acceleration, provide maximum dry traction, and better wet performance which helps to reduce rolling resistance as well as providing shorter stopping distances.

Disc brake

A type of brake that has two basic components: a flat rotor (disc) that turns with the wheel and a caliper that is stationary. When the brake pedal is depressed, linkage (mechanical or hydraulic) causes the caliper to force its heat-resistant brake pads against both sides of the rotating disc thus slowing or stopping the wheel.

Displacement

This is a general automotive term describing the sum of the volume of the cylinders of the engine. The displacement of a Formula One engine is limited to 2.4l , equally divided between the 8 cylinders.

Downforce

Force generated by air passing over the wings, plus the interaction of the flat bottom of the car and the track surface.

Drag

All cars experience drag. It is the resistance a car encounters from the air as it moves forward.

Drive-through penalty

This is one of the two penalties that can be given to drivers during a race. When imposed, the offending drive must drive into the pit lane and continue through without stopping at his pit box. The penalty lies in the limited speed that is permitted in the pitlane, resulting in a considerable loss of time compared to 300 km/h on the main straight.

Dry sump

A lubrication system in which the engine's supply of oil is not contained in the crankcase (sump) but is pumped to the engine from an external container. This system allows the crankcase to be reduced in size and the engine to be installed lower in the chassis, and eliminates the oil starvation most conventional oiling systems suffer when subjected to the accelerative, braking, and cornering forces generated by a racing car.

Dyno

A contraction of 'Dynamometer', an engine-testing device used in the shop that measures power and simulates the loads and environment of a racing engine. A dyno is an expensive piece of computerized equipment that measures the efficiency of a motor.