Glide ratio is an aviation term that refers to the distance an aircraft will move forward for any given amount of lost altitude (the cotangent of the downward angle). Alternatively it is also the forward speed divided by sink speed (unpowered aircraft): It has been suggested that Modern Aviation be merged into this article or section. ... Airbus A380 An aircraft is any machine capable of atmospheric flight. ... Trigonometry In trigonometry, the cotangent is a function (see trigonometric function) defined as: or An interpretation of the cotangent of an angle x is as follows. ...

The terms glide ratio and lift-to-drag ratio are interchangeable. This is true because the force vectors also determine the direction of travel with the engine off. Glide ratio is the preferred term for unpowered aircraft, and lift-to-drag ratio the preferred term for aerodynamics literature and powered flight. This parameter effectively describes the efficiency of the airframe. In aerodynamics, the lift-to-drag ratio, or L/D ratio (ell-over-dee, as opposed to ell-dee), is the amount of lift generated by a wing, compared to the drag it creates by moving through the air. ... In aerodynamics, the lift-to-drag ratio, or L/D ratio (ell-over-dee, as opposed to ell-dee), is the amount of lift generated by a wing, compared to the drag it creates by moving through the air. ...

For instance, general aviation aircraft like the Cessna 150 will move forward 7 feet for every foot of altitude lost, resulting in a glide ratio of 7:1. A modern sailplane may have a glide ratio as high as 60:1, with fabric hang gliders averaging about 12:1, paraglider (Slowest aircraft) 7:1 and airliners about 17:1. General aviation (abbr. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Gliders are un-powered heavier-than-air aircraft. ... Hang gliding is one of the windsports. ... Paragliding (known in some countries as parapenting) is a recreational and competitive sport that is best described as a hybrid of hang gliding and parachuting. ... An Airbus A340 airliner operated by Air Jamaica An airliner is a large fixed-wing aircraft whose primary function is the transportation of paying passengers. ...

Importance of the glide ratio in gliding

Although the best glide ratio is important when measuring the performance of a glider, its ability to achieve a good glide ratio at high speed determines its success when racing (see article on gliding). However all soaring aircraft need to be able to climb effectively in the available thermals. This normally limits the maximum tolerable sink rate. A sink rate of 1.0 m/s is the most that a practical hang glider or paraglider could have; sailplanes have an even better performance. At higher sink rates soaring would be difficult because air rising at higher rates is less common. Consequently an airliner may have a better glide ratio than a hang glider, but it will not be able to thermal because of its much higher stall speed and so its much higher sink rate. (Note that the Boeing 767 in the Gimli Glider incident achieved a glide ratio of only 12:1.) Gliders are heavier-than-air aircraft primarily intended for unpowered flight. ... Gliding (or soaring) is a recreational activity and competitive sport where individuals fly un-powered aeroplanes known as gliders or sailplanes. ... Air Canada Boeing 767-300 British Airways Boeing 767-300 The Boeing 767 is a commercial passenger airplane manufactured by Boeing Commercial Airplanes. ... The Gimli Glider is the name given to an infamous incident in aviation history. ...

The loss of height can be measured at several speeds and plotted on a "polar curve" to calculate the best speed to fly in various conditions, such as when flying into wind or when in sinking air. Other polar curves can be measured by loading the glider with water ballast. When ballast is carried, the best glide ratio is achieved at higher speeds (the glide ratio is not increased). Gliders are heavier-than-air aircraft primarily intended for unpowered flight. ...

See also

• Approach slope
• Gliding
• Gimli Glider