A glider or sailplane is a type of glider aircraft used in the leisure activity and sport of gliding. The unpowered aircraft use naturally occurring currents of rising air in the atmosphere to remain airborne. Gliders are aerodynamically streamlined and are capable of gaining altitude and remaining airborne, and maintaining forward motion.
1 Types of gliders 2 History 3 Glider design 4 Launch and flight 5 Glide slope control 6 Landing 7 Instrumentation and other technical aids 8 Markings 9 Comparison of gliders with hang gliders and paragliders 10 Competition classes of glider 11 Major manufacturers of gliders 12 See also 13 References 14 External links
Types of gliders
ASH25M—a self-launching two-seater glider
Gliders benefit from producing the least drag for any given amount of
lift, and this is best achieved with long, thin wings, a fully faired
narrow cockpit and a slender fuselage.
HAWA Vampyr 1921
For early attempts to fly, see Early flying machines.
Sir George Cayley's gliders achieved brief wing-borne hops from around
1849. In the 1890s,
Instrument panel of a typical modern glider (Glaser-Dirks DG-101G ELAN). Click on the image for an explanation of the instrumentation.
The early gliders were made mainly of wood with metal fastenings,
stays and control cables. Later fuselages made of fabric-covered steel
tube were married to wood and fabric wings for lightness and strength.
New materials such as carbon-fiber, fiber glass and
The two most common methods of launching gliders are by aerotow and by winch. When aerotowed, the glider is towed behind a powered aircraft using a rope about 60 meters (about 200 ft) long. The glider pilot releases the rope after reaching the desired altitude. However, the rope can be released by the towplane also in case of emergency. Winch launching uses a powerful stationary engine located on the ground at the far end of the launch area. The glider is attached to one end of 800–1200 metres (about 2,500–4,000 ft) of cable and the winch rapidly winds it in. The glider can gain about 900–3000 feet (about 300–900 metres) of height with a winch launch, depending on the head wind. Less often, automobiles are used to pull gliders into the air, by pulling them directly or through the use of a reverse pulley in a similar manner to the winch launch. Elastic ropes (known as bungees) are occasionally used at some sites to launch gliders from slopes, if there is sufficient wind blowing up the hill. Bungee launching was the predominant method of launching early gliders. Some modern gliders can self-launch with the use of retractable engines and/or propellers, which can also be used to sustain flight once airborne (see motor glider). Once launched, gliders try to gain height using thermals, ridge lift, lee waves or convergence zones and can remain airborne for hours. This is known as "soaring". By finding lift sufficiently often, experienced pilots fly cross-country, often on pre-declared tasks of hundreds of kilometers, usually back to the original launch site. Cross-country flying and aerobatics are the two forms of competitive gliding. For information about the forces in gliding flight, see lift-to-drag ratio. Glide slope control Pilots need some form of control over the glide slope to land the glider. In powered aircraft, this is done by reducing engine thrust. In gliders, other methods are used to either reduce the lift generated by the wing, increase the drag of the entire glider, or both. Glide slope is the distance traveled for each unit of height lost. In a steady wings-level glide with no wind, glide slope is the same as the lift/drag ratio (L/D) of the glider, called "L-over-D". Reducing lift from the wings and/or increasing drag will reduce the L/D allowing the glider to descend at a steeper angle with no increase in airspeed. Simply pointing the nose downwards only converts altitude into a higher airspeed with a minimal initial reduction in total energy. Gliders, because of their long low wings, create a high ground effect which can significantly increase the glide angle and make it difficult to bring the glider to Earth in a short distance.
Sideslipping A slip is performed by crossing the controls (rudder to right with ailerons to left, for example) so that the glider is no longer flying aligned with the air flow. This will present one side of the fuselage to the air-flow significantly increasing drag. Early gliders primarily used slipping for glide slope control. Spoilers Spoilers are movable control surfaces in the top of the wing, usually located mid-chord or near the spar which are raised into the air-flow to eliminate (spoil) the lift from the wing area behind the spoiler, disrupting the spanwise distribution of lift and increasing lift-induced drag. Spoilers significantly increase drag. Air brakes Air brakes, also known as dive brakes, are devices whose primary purpose is to increase drag. On gliders, the spoilers act as air brakes. They are positioned on top of the wing and below the wing also. When slightly opened the upper brakes will spoil the lift, but when fully opened will present a large surface and so can provide significant drag. Some gliders have terminal velocity dive brakes, which provide enough drag to keep its speed below maximum permitted speed, even if the glider were pointing straight down. This capability is considered a safer way to descend without instruments through cloud than the only alternative which is an intentional spin. Flaps Flaps are movable surfaces on the trailing edge of the wing. The primary purpose of flaps is to change the camber of the wing and so change the lift-to-drag ratio of the wing. This reduces the stall speed and so allows reduced landing speeds. It was possible to lower the flaps on some older gliders by up to 90 degrees to increase drag significantly as well as increasing lift coefficient when landing. Another feature that flapped gliders possess are negative flaps that are also able to deflect the trailing edge upward. This feature is included on some competition gliders in order to reduce the pitching moment on the wing and allowing better glide ratios at higher speeds (a particularly desirable characteristic for racing gliders). Parachute Some high performance gliders from the 1960s and 1970s were designed to carry a small drogue parachute because their air brakes were not particularly effective. This was stored in the tail-cone of the glider during flight. When deployed, a parachute causes a large increase in drag, but has a significant disadvantage over the other methods of controlling the glide slope. This is because a parachute does not allow the pilot to finely adjust the glide slope. Consequently, a pilot may have to jettison the parachute entirely, if the glider is not going to reach the desired landing area.
Landing Early glider designs used skids for landing, but modern types generally land on wheels. Some of the earliest gliders used a dolly with wheels for taking off and the dolly was jettisoned as the glider left the ground, leaving just the skid for landing. A glider may be designed so the center of gravity (CG) is behind the main wheel so the glider sits nose high on the ground. Other designs may have the CG forward of the main wheel so the nose rests on a nose-wheel or skid when stopped. Skids are now mainly used only on training gliders such as the Schweizer SGS 2–33. Skids are around 100mm (3 inches) wide by 900mm (3 feet) long and run from the nose to the main wheel. Skids help with braking after landing by allowing the pilot to put forward pressure on the control stick, thus creating friction between the skid and the ground. The wing tips also have small skids or wheels to protect the wing tips from ground contact. In most high performance gliders the undercarriage can be raised to reduce drag in flight and lowered for landing. Wheel brakes are provided to allow stopping once on the ground. These may be engaged by fully extending the spoilers/air-brakes or by using a separate control. Although there is only a single main wheel, the glider's wing can be kept level by using the flight controls until it is almost stationary. Pilots usually land back at the airfield from which they took off, but a landing is possible in any flat field about 250 metres long. Ideally, should circumstances permit, a glider would fly a standard pattern, or circuit, in preparation for landing, typically starting at a height of 300 metres (1,000 feet). Glide slope control devices are then used to adjust the height to assure landing at the desired point. The ideal landing pattern positions the glider on final approach so that a deployment of 30–60% of the spoilers/dive brakes/flaps brings it to the desired touchdown point. In this way the pilot has the option of opening or closing the spoilers/air-brakes to extend or steepen the descent to reach the touchdown point. This gives the pilot wide safety margins should unexpected events occur. Instrumentation and other technical aids
Schempp-Hirth Janus-C in flight, showing instrument panel configured in the basic-T, with airspeed, turn and bank and altitude displays across the top row; below a GPS-driven computer, with wind and glide information, drives two electronic variometer displays to the right. The yaw string and compass are above the glare shield
In addition to an altimeter, compass, and an airspeed indicator,
gliders are often equipped with a variometer, turn and bank indicator
and an airband radio (transceiver), each of which may be required in
some countries. An
Emergency Position-Indicating Radio Beacon
Provide the glider's position in 3 dimensions by a moving map display
Alert the pilot to nearby airspace restrictions
Indicate position along track and remaining distance and course
Show airports within theoretical gliding distance
Determine wind direction and speed at current altitude
Show historical lift information
After the flight the
So that ground-based observers may identify gliders in flight or in
gliding competition, registration marks ("insignias" or "competition
numbers" or "contest ID") are displayed in large characters on the
underside of a single wing, and also on the fin and rudder.
Registration marks are assigned by gliding associations such as the US
Soaring Society of America, and are unrelated to national
registrations issued by entities such as the US Federal Aviation
Administration. This need for visual ID has somewhat been
Paragliders Hang gliders Gliders/Sailplanes
Undercarriage pilot's legs used for take-off and landing pilot's legs used for take-off and landing aircraft takes off and lands using a wheeled undercarriage or skids
Wing structure entirely flexible, with shape maintained purely by the pressure of air flowing into and over the wing in flight and the tension of the lines generally flexible but supported on a rigid frame which determines its shape (note that rigid-wing hang gliders also exist) rigid wing surface which totally encases wing structure
Pilot position sitting supine in a seated harness usually lying prone in a cocoon-like harness suspended from the wing; seated and supine are also possible sitting in a seat with a harness, surrounded by a crash-resistant structure
Speed range (stall speed – max speed) slower – typically 25 to 60km/h for recreational gliders (over 50km/h requires use of speed bar), hence easier to launch and fly in light winds; least wind penetration; pitch variation can be achieved with the controls faster - stall speed about 30km/h. Never exceed speed up to 90km/h maximum speed up to about 280 km/h (170 mph); stall speed typically 65 km/h (40mph); able to fly in windier turbulent conditions and can outrun bad weather; exceptional penetration into the wind
Maximum glide ratio about 10, relatively poor glide performance makes long distance flights more difficult; current (as of May 2017[update]) world record is 564 kilometres (350 mi) 10 (beginners hang glider), 15 (competition flex wing hang glider), 19 (rigid wing hang glider) open class sailplanes – typically around 60:1, but in more common 15–18 meter span aircraft, glide ratios are between 38:1 and 52:1; high glide performance enabling long distance flight, with 3,000 kilometres (1,900 mi) being current (as of November 2010[update]) record
Turn radius tighter turn radius somewhat larger turn radius even greater turn radius but still able to circle tightly in thermals
Landing smaller space needed to land, offering more landing options from cross-country flights; also easier to carry to the nearest road longer approach and landing area required, but can reach more landing areas due to superior glide range when flying cross-country, glide performance can allow glider to reach 'landable' areas, possibly even a landing strip and an aerial retrieve may be possible but if not, specialized trailer needed to retrieve by road. Note some sailplanes have engines that remove the need for an out-landing
Learning simplest and quickest to learn teaching is done in single and two-seat hang gliders teaching is done in a two-seat glider with dual controls
Convenience packs smaller (easier to transport and store) more awkward to transport and store; longer to rig and de-rig; often transported on the roof of a car trailers are typically 10 m (30 ft) long; if it has not been stored in a hangar, rigging & de-rigging takes about 20 minutes
Cost cost of new is €1500 and up, cheapest but shortest lasting (around 500 hours flying time, depending on treatment), active second-hand market €3000 (beginners hang glider) up to €17000 (rigid wing hang glider), life time is more than one decade cost of new glider very high but it is long lasting (up to several decades), so active second-hand market; typical cost is from €2,000 to €145,000
Competition classes of glider
DG Flugzeugbau DG-1000
Eight competition classes of glider have been defined by the FAI. They are:
Standard Class (No flaps, 15 m wing-span, water ballast allowed)
15 metre Class (Flaps allowed, 15 m wing-span, water ballast
18 metre Class (Flaps allowed, 18 m wing-span, water ballast
Open Class (No restrictions except a limit of 850 kg for the
maximum all-up weight)
Two Seater Class (maximum wing-span of 20 m), also known by the
German name "Doppelsitzer"
Club Class (This class allows a wide range of older small gliders with
different performance and so the scores have to be adjusted by
handicapping. Water ballast is not allowed).
World Class (The FAI
Major manufacturers of gliders Main article: list of gliders A large proportion of gliders have been and are still made in Germany, the birthplace of the sport. In Germany there are several manufacturers but the three principal companies are:
DG Flugzeugbau GmbH Schempp-Hirth GmbH Alexander Schleicher GmbH & Co
Germany also has
Stemme and Lange Aviation. Elsewhere in the world,
there are other manufacturers such as Jonker Sailplanes in South
Africa, Sportinė Aviacija in Lithuania,
Glider types List of gliders Military glider
Rhön-Rossitten Gesellschaft Schweizer brothers
Other unpowered aircraft
Rotor kite Unpowered aircraft
Unpowered flying toys and models
Paper plane Radio-controlled glider
^ FAA Glider handbook
^ a b Definition of gliders used for sporting purposes in FAI Sporting
^ Civil Aviation Authority: Personnel Licensing Department
(2005-12-02). LASORS 2006: The Guide for Pilots. The Stationery
Office. ISBN 978-0-11-790501-6.
^ Flight magazine 1954
^ "History of
Wikimedia Commons has media related to Gliders.
Look up sailplane in Wiktionary, the free dictionary.
Information about all types of glider
Sailplane Directory – An enthusiast's web-site that lists manufacturers and models of gliders, past and present.
FAI records – sporting aviation page with international world soaring records in distances, speeds, routes, and altitude Links to all national gliding federations
v t e
Types of aircraft by methods of thrust and lift
Lift: Lighter than air gas Lift: Fixed wing Lift: Unpowered rotor Lift: Powered rotor
Unpowered free flight (Free) balloon Glider Helicopter, etc. in autorotation (None – see note 2)
Tethered (static or towed) Tethered balloon Kite Rotor kite (None – see note 2)
Powered Airship Airplane, ornithopter, etc. Autogyro Helicopter, gyrodyne
Note 1: A tiltwing or tiltrotor aircraft functions as an aeroplane during normal (horizontal) flight and as a helicopter during low-speed flight.
Note 2: For full-size aircraft with powered rotors the rotor is normally tilted to achieve thrust (e.g. in a helicopter). Some toys (e.g. balloon helicopter) do have a powered rotor with no means to tilt the rotor to produce horizontal thrust.
Note 3: Ground effect vehicles and hovercraft are not included in the table, nor are experimental aircraft with novel thrust / lift solutions (e.g. coleopter, Flying Bedstead, Avrocar and flettner airplane) or balloon-wing hybrids (e.g. kytoon and hybrid airship).