Roll moment is a moment, which is a product of a force and a distance, that tends to cause a vehicle to roll, that is to rotate about its longitudinal axis.

Landcraft

vehicle dynamics For motorized vehicles, such as automobiles, aircraft, and watercraft, vehicle dynamics is the study of vehicle motion, e.g., how a vehicle's forward movement changes in response to driver inputs, propulsion system outputs, ambient conditions, air ...

, the roll moment can be calculated as the product of three quantities: #the vehicle's

sprung mass Sprung mass (or sprung weight), in a vehicle with a suspension, such as an automobile, motorcycle, or a tank, is the portion of the vehicle's total mass that is supported by the suspension, including in most applications approximately half of the ...

, the portion of its mass supported by the

suspension Suspension or suspended may refer to: Science and engineering * Suspension (topology), in mathematics * Suspension (dynamical systems), in mathematics * Suspension of a ring, in mathematics * Suspension (chemistry), small solid particles suspende ...

, #whatever lateral acceleration that the vehicle is experiencing, usually

centripetal acceleration In mechanics, acceleration is the rate of change of the velocity of an object with respect to time. Accelerations are vector quantities (in that they have magnitude and direction). The orientation of an object's acceleration is given by th ...

from a turn, and #the vertical distance between the vehicle's roll axis and its center of mass. In two-axle vehicles, such as cars and some trucks, the roll axis may be found by connecting the roll center of each axle by a straight line. In single-track vehicles, such as bicycles and motorcycles, the roll axis may be found by connecting the contact patches of each tire by a straight line.

Aircraft

In aeronautics, the roll moment is the product of an aerodynamic force and the distance between where it is applied and the aircraft's center of mass that tends to cause the aircraft to rotate about its roll axis. The roll axis is usually defined as the longitudinal axis, which runs from the nose to the tail of the aircraft. A roll moment can be the result of wind gusts, control surfaces such as

ailerons An aileron (French for "little wing" or "fin") is a hinged flight control surface usually forming part of the trailing edge of each wing of a fixed-wing aircraft. Ailerons are used in pairs to control the aircraft in roll (or movement around ...

, or simply by flying at an angle of sideslip. See

flight dynamics Flight dynamics in aviation and spacecraft, is the study of the performance, stability, and control of vehicles flying through the air or in outer space. It is concerned with how forces acting on the vehicle determine its velocity and attit ...

Watercraft

watercraft Any vehicle used in or on water as well as underwater, including boats, ships, hovercraft and submarines, is a watercraft, also known as a water vessel or waterborne vessel. A watercraft usually has a propulsive capability (whether by sail, ...

, roll is the rotation around the ships longitudinal (front-back or bow-stern) axis. ''Heel'' refers to an offset from normal on this axis that is intentional or expected, as caused by wind pressure on sails, turning, or other crew actions. ''List'' refers to an unintentional or unexpected offset, as caused by flooding, battle damage, shifting cargo, etc.

References

External links

Suspension Geometry Calculator
Classical mechanics Vehicle technology {{Automotive-tech-stub