A Glossary of Gliding

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

Every sport has its own language and technical terms, and gliding is no exception. Some of those you are likely to meet when gliding are listed below. Use the letter list above to navigate through the Glossary.

 

 

'A' Badge

Awarded to those who have completed their first solo flight in a glider and displayed a basic knowledge of the rules of the air. Top

 

Aerotow

The most expensive launch method. The glider is towed into the air behind a powerful single-engined plane (known as the tug) and released at altitude. Some clubs always take the glider up to 2000' unless requested otherwise; at other Clubs you stay on tow until you get as high as you wish (or can afford). Top

 

Aileron

Control surfaces on the trailing edge of the wing. They control the glider's movement in roll. Movement of the stick (the control column) left or right controls the ailerons. Top

 

Air Brakes

Large vertical plates which can be extended from inside of the wing. They mainly increase drag on the glider, but also reduce lift a little bit. They control the rate of descent of the aircraft, and this in turn is how the approach to land is controlled. Top

 

Airspeed Indicator

The 'ASI' measures the apparent speed of the air flowing past the glider. It does not measure the speed with which the glider is tracking across the ground, as this is affected by the wind. The indicated airspeed differs from the true airspeed, and is less than the true airspeed. The difference is greater the higher you are. Top

 

All Out

The final signal given before a launch once the slack has been taken out of the tow cable and it is taut, or nearly so. Usually the decision to launch is made by the launch point controller, but if he/she can't see the winch cable clearly, a verbal or visual signal may be given by the person holding wingtip. Find out how your club does things!.Top

 

 

Altimeter

Essentially a barometer which displays the height of the aircraft. It usually looks like a three handed clock. The big hand at the front indicates hundreds of feet, the medium sized hand indicates thousands, and the little hand at the back shows tens of thousands of feet. Top

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Angle of attack

The angle made by the chord of the wing with the relative air flow. It is NOT the angle the wing makes against the horizon. Lift increases as the angle of attack increases, until at about 16 degrees, the air flow can't hug the surface of the wing and flow smoothly over it, and instead breaks free of the surface as turbulent bubbles. At this point The wing then generates very little lift, and thus the wing stall. Top

 

Approach

The final part of a flight and of the circuit, where the glider comes in to land. Top

 

Attitude

The relative position of the glider against the horizon. It can be nose up or nose down, or banked to the left or right. Top

 

 

Ballast

Gliders have a minimum weight (or ballast) requirement for the person occupying the cockpit. If you weigh less than this amount you will have to carry lead ballast weights. There is also a maximum weight limit, which is often 242 lb. total. For two seaters, each seat has it's own weight limitations, and a combined total as well. Pilots always check their "flying weight" against these figures. This should include the weight of your parachute (usually about 15 lb.). The minimum weight requirement is to keep the centre of gravity within the acceptable range for ease of control of the glider. Top

 

Bank

A glider is banked over when one wing is lower than the other. Usually this means one wingtip is below the horizon and the other above it, but if it is only banked a tiny bit, one wingtip will be closer to the horizon than the other. See roll. Top

 

 

Belly Hook

See C of G hook. Top

 

 

BGA

British Gliding Association: The governing body of the sport in the United Kingdom. The Civil Aviation Authority (CAA) has handed over general control of gliding to the BGA. As long as the BGA makes sensible rules which its members obey, and controls the sport properly, the CAA will keep out of gliding. We like it that way. Don't rock the boat, because you know what happens when the government gets involved with something! Top

 

Blue

The colour of the sky. In particular, a sky with no clouds, especially no cumulus clouds. This makes soaring trickier, as the glider pilot has less clues as to where to find the next reliable bit of lift. Most pilots hate blue days. Top

 

 

Bronze 'C'

Completion of 50 solo flights, or 20 solo flights and 10 hours flight time, a general skills flying test where the pilot demonstrates to an instructor competent flying skills, with understanding of stalls and spins and accurate landing (including simulated field landings) and a pass in a written (multiple choice) examination qualifies a glider pilot for the Bronze Award. It is a UK only award, but it is similar in depth of knowledge and ability to the US glider pilot's license requirements. This is the minimum requirement for cross-country flying, but the UK Cross Country endorsement is the common standard before such flights can be made. Most sensible clubs require inexperienced cross country pilots to obtain authorisation from an instructor before flying off cross country. It is somewhat irresponsible to let a pilot with little or no experience make their own decisions on where to and when to set off on a cross country flight. Top

 

 

C of G

The centre of gravity of the glider. The aircraft's manufacturer sets a minimum and maximum position for this, and the ballast limits are calculated to keep the C of G within these limits. Top

 

C of G Hook

Centre of Gravity hook. Used in the winch launch of gliders, sited under the belly of the glider close to the main wheel or skid. Top

 

C of A

Certificate of Airworthiness; effectively an MOT for gliders. Top

 

Cable Release

The yellow knob in the cockpit which releases the cable from the nose or belly hook at the top of the launch. Top

 

Canopy

The perspex lid of the cockpit. Handle with care and hold it open. Do not pull the aircraft using the canopy. These are very expensive pieces of plastic, usually with very few optical imperfections when new. Keep your sticky hands off the surface! Top

 

 

CB-SIFT-CEB

Mnemonic for the checks made prior to every launch, used everywhere in the UK, listed below. Other countries use their own variation on this set of checks.

• Controls,
• Ballast,
• Straps,
• Instruments,
• Flaps,
• Trim,
• Brakes,
• Eventualities.
• Canopy, Top

CFI

In the UK, the Chief Flying Instructor at a club. God listens when the CFI speaks. In the USA however, it means Commercial Flying Instructor, where a CFI-G is a commercial pilot with a glider rating. Note that in the US to add this extra gliding rating may only involve about 20 flights in a glider! Top

 

 

Chord

The line joining the leading edge of a wing to the trailing edge. Also the width of the wing. Top

 

 

Circuit

A planned flight path undertaken prior to landing, designed to ensure that the aircraft arrives at the correct height at the correct place to make the final approach to landing. Top

 

Cockpit (front)

When flying with an instructor in a two-seater aircraft, the pupil sits in the front cockpit. When you first go solo, you fly from here. Therefore if a student tried to learn from the rear cockpit, a) it would be harder for them, and b) they would then have to learn how to fly from the front cockpit as the view is very different. Top

 

Cockpit (rear)

This is where your instructor sits when s/he is teaching you how to fly the glider. The instructor's controls are mechanically linked to the pupil's, allowing him/her to feel exactly what is being done, where any mistakes are being made and allowing any necessary corrections to be promptly made. Top

Control column

The stick in front of the pilot which is used to move the controls around. Don't hold it tightly as this makes it tricky to move it by small amounts and hides any small movements caused by the outside air. Don't hold it with two hands, for the same reason. Hold it with your right hand, whether or not you are right or left handed - there are other controls for your left hand to use, and swapping hands confuses things. It is NOT a joystick - that's a thing you use to play games with on a computer.

 

Control surface

The ailerons, elevator and rudder are the control surfaces, which control the glider in pitch, roll and yaw respectively. Also known as "The waggley bits". Top

 

 

Cross Country

Sometimes abbreviated to XC. A flight that takes you away from the airfield. Good pilots define cross country flying as being out of gliding range of the airfield for most of the flight. Novices usually settle for being a little bit further away than normal. A flying day is often classified according to how far it would be possible for a good pilot to fly cross country that day. Hence you frequently hear "it was a 300 K day" or "a good 500 K day" or "just a 100 K day", where K means kilometers. Most responsible clubs only permit novice cross country pilots to attempt a task one level down from the actual day's rating, to give them a chance of completing the task safely. Most responsible clubs also control where and when less experienced pilots go cross country, as letting a beginner decided this is a recipe for disaster. For many pilots, but not all, cross country flying is the main reason for gliding, the ultimate challenge to their skills. Top

 

Crosswind

Wind at an angle to the direction of travel of the aircraft, especially important during take-off and landing. It causes the glider to drift at an angle over the ground.
The glider is not flying sideways through the air, it is flying straight through the air but the box of air it is inside is moving relative to the ground.Top

 

Cumulus

Clouds marking the top of a rising column of warm air and, therefore, a very reliable marker for thermals. The clouds seen on a summer day with cauliflower tops. Glider pilots love them. If about 3/8 of the sky has well formed cumulus with some vertical development, conditions are usually good. Top

 

 

DI

Daily Inspection: a term for the safety inspection of all equipment from the tractors used to tow gliders and cables around, including the winches and tug planes and all the components of the gliders themselves prior to every day's gliding. At most clubs, only trained pilots carry out the glider DI, and it is usually signed for in an inspection book. Top

 

 

Diamonds

The ultimate badge awarded to glider pilots, taken in three parts; a gain of height of more than 5,000 m, measured from a low point after the release at the top of the launch to a following high point, completion of a cross country flight of more than 300 km using up to three TPs, and a flight of more than 500 km. Top

 

Drag

Stick your hand out of the window of a moving carm facing forward, to experience drag. It's a force trying to slow down the glider due to air friction, turbulence and viscosity. Drag increases with lift, and is also dependent on the shape of the object/aircraft. Glider pilots and designers will try anything to reduce drag, because the lift to drag ratio of a glider is one of the main things defining it performance. Top

 

Elevator

Part of the tailplane. The elevator is controlled by the control column, and it controls the glider in pitch, which is the nose down / nose up attitude of the glider. Top

 

FAI

Federation Aeronautique International: The international supervising body for the sport. The Silver badge is recognised by all FAI federated gliding associations. The FAI sets the rules for qualifications and international competitions. Top

 

Field landing

You do not always make it back to an airfield when flying cross-country therefore, inevitably, you will end up landing in some farmer's field. Also known as an out-landing, or aux vache in France, or a paddock landing in Australia. If you land out, the adventure has just begun. Top

 

 

 

Final Turn

The phase of a circuit between the base leg and the approach. Contrary to what some students and solo pilots seem to think, the final turn is just an ordinary turn, it's nothing special at all. It should be like all other turns, and finish with the glider at the same attitude and air speed that it started with. It does NOT mean you lower the nose and increase speed during this turn. Top

 

Flaps

Camber changing devices on the trailing edge of a wing. They make small adjustments to the stalling speed of a glider, and make the wing more suitably shaped for flight at different speed ranges. A curved wing is more suitable for slow speed flight, a "flat" wing is more suitable for high speed flight. Flaps make gliders more expensive. As with any multi-position object, the more flap settings there are, the more likely you are to be using the wrong setting. ;-) Top

 

Getting away

Soaring successfully enough to be able to chose where to go next. It usually means getting high. Once you are free to choose where to move on to next, the flight becomes very much more enjoyable. Getting away is the aim of all solo pilots, even if they then choose to stay local to the airfield. See sledge ride. Top

 

Gold badge, Gold C

Awarded after completing the following tasks, not necessarily on a single flight. Five hours endurance flight, a height gain of 3,000 m above a previous low point, recorded after the launch, and a flight of more than 300 km. Top

 

GPS

Global Positioning System: Satellite-based navigation system capable of reporting your position anywhere on Earth to within 10 metres, and also your height. More usefully, it can tell you the distance and direction to wherever you are flying. Top

 

Ground Handling

Pushing a glider about on the ground, towing it behind tractors and parking it safely. Don't push on any part of a glider before you know which parts are strong enough to withstand pressure. Basically, if the part can move or be opened, don't push or pull it. Top

 

Harness

The seatbelt, the straps. 4 or 5 belts lock into a central clasp - quickly released in an emergency. You will ALWAYS fly with the harness properly fitted, for the duration of the entire flight, it is not an optional extra. Top

 

 

 

 

K21

A two seat glass fibre training glider which can also be used for aerobatics, cross country and competition flight. A very user friendly glider. Some people think it is TOO easy to fly. Top

 

Leading edge

The front edge of the wing. The opposite of the trailing edge. Top

 

Lift

Upward force generated by a wing when air flows over it. The amount of lift generated depends on the shape and curvature of the wing

 

Log Book

Completed after each flight, the log book provides a record of the experience of each pilot. You should get one when you start flying. Top

 

Loop

An aerobatic manoeuvre. A vertical circle in the sky. Aerobatics have to be taught by a qualified instructors. Only idiots try to teach themselves aerobatics. Top

 

 

 

Nose Hook

Used for the aerotow cable attachment and sited in the nose of the aircraft. In some gliders, no nose hook is fitted, and the belly hook is used instead. These gliders require a little bit more finesse from the pilot when being launched. Top

 

Pitch

A change of the glider's attitude, where the nose moves down or up is called a change of pitch. Pitch changes are usually much smaller than the student thinks - glancing to the side usually shows that the glider is often no more than 10 - 20 degrees nose up or down. Forward and backward movement of the stick moves the elevator which produces a force which causes the glider to tilt nose-up or nose-down, controls the slope of the glide and, therefore, the speed. Top

 

Retrieve

Winch cables need to be brought back to the launch point after a launch. This is done by towing them back with a car or tractor. Some training is needed to do this, being able to drive does not mean you can do a cable retrieve.
Much more interesting and fun is a retrieve from a field landing. Outrageous stories about retrieves are legendary, and usually true! Top

 

Ridge soaring

Wind blowing up the side of a hill gets deflected upwards. It can be used as a source of lift as the air now has a vertical component to its motion. The higher and longer the ridge, the better. Top

 

Roll

Movement around the axis running from the front to the rear of the aircraft along the fuselage is called roll. It is controlled by sideways movement of the stick which, in turn, moves the ailerons. To turn a glider, it must be rolled to a banked position using the ailerons. The rudder is used to prevent adverse yaw caused by the upgoing wing (the one on the outside of the turn). Top

 

Round Out

The part of the approach during which the descent is curtailed by gentle, smooth backward movement on the stick causing the glider to perform a held-off landing (one where it floats gently down onto the ground). The glider is not stalled in this process, it just settles down gently onto the ground. In the US they seem to fly the glider onto the ground to land it, unlike the rest of the world. There is no benefit to doing this, and several disadvantages. Top

 

Rudder

Vertical control surface at the rear of the aircraft controls movement around the yaw axis which runs vertically down through the centre of gravity of the glider. Controlled by the foot pedals. By itself yaw swings the nose left or right. Yaw is required to balance roll in a turn, to bring the nose round the way the glider is turning. (The rudder is NOT used by itself to turn a glider.) Top

 

Sailplane

Another word for a glider, used mainly by Americans. Many, many years ago, it was used to differentiate between those gliders with very poor performance and those capable of soaring. (Soaring is now dependent on the weather and pilot ability.) Top

 

Silver 'C'

Requires a 5 hour flight, 1,000 m height gain from a low point recorded after the launch, and a minimum of a 50 km distance. These can be achieved in separate flights, and sensible clubs often require that the height gain and the five hour endurance flight (or a reasonably good attempt at it) are completed before the cross country part is attempted. In other words, if you can't fly successfully near the local airfield, you really don't want to be 25 kms away with no idea what to do next! An internationally recognised award, it is the real minimum at which you can call yourself "a pilot". Top

 

Sink

Air traveling downwards, increasing your rate of descent, usually when you don't want it to. Avoid sink, fly faster to get through it sooner! What goes up must come down, so where there is lift, there is sink nearby. Strangely the reverse isn't usually true. Top

 

Sledge ride

A flight where you were launched, then simply descended continuously without finding any lift. The opposite of getting away. Top

 

Sniffer

At a gliding competition, a good pilot who is not actually competing is launched early in the day, or just before the organisers think the weather is getting good enough to race. This pilot has to "sniff out the thermals" and assess how good the weather really is, relaying the information back to the organisers on the ground who then make the decisions as to whether or not they will launch the competitors, and which of the possible tasks they will be racing over. It isn't very nice to be launched in a competition to discover the weather is not as advertised and that the result of the competition now depends more on luck than judgement, or that 30 or 50 gliders will struggling in the one thermal near the airfield, all at the same height. Sniffers have to be good pilots, as the organisers and competitors are relying on them to accurately report the actual conditions. It's not unusual to have a local Regional, National, or even World competitor acting as the sniffer. Top

 

Soaring

Remaining airborne through intelligent use of rising air sources (thermals, ridge lift and wave), and a bit of pilot skill. The aim of glider pilots is to soar, to stay up longer. When high, the pilot is free to chose where s/he wishes to go next. The invisible string tying you to the airfield can be broken. Top

 

Spin

A condition of rapid descent accompanied by rotation caused by yaw occurring close to the stall. This stalls the inner wing, but leaves the outer wing unstalled and the glider autorotates. Recovery is achieved by applying opposite rudder to oppose the spin and just enough forward stick movement to reduce the angle of attack, and unstall the glider. Then you centralise the controls and gently raise the nose back to the normal glider attitude. Don't slam the control column forwards or backwards. Learning how to spin isn't important. Learning how to stop a spin, or prevent it starting, IS important. Spins are under control, you can start and stop when you chose to. ALL gliders have been designed to recover from a spin by using the standard technique. Some are reluctant to spin, but none are unspinable, whatever your friends may tell you. Top

 

Stall

A condition where a glider's wing cannot produce enough lift, due to the angle of attack being too high. The stalling speed depends on the load (weight, or g force) on the glider. Most wings stall when the angle of attack is about 16 degrees to the relative air flow. However you can't measure this angle in flight. Stalling is accompanied with a high rate of descent, and a buffeting from the turbulent air flowing over the wings and control surfaces. It is also much quieter than normal flight, and moving the stick backwards doesn't raise the nose. The controls seem ineffective. To recover from a stall, smoothly and gently move the stick forwards to reduce the angle of attack, then recover smoothly to the normal attidute.Don't slam the stick forwards or backwards. Top

 

 

Stick

One of the main controls of the glider. In gliders it takes the form of a control column between the legs of the pilot which then replaces the familiar driving wheel style yolk seen in many powered aircraft. It controls the glider in pitch and roll. Note that computer games use a joystick, but gliders have a control column. Top

 

Take up slack

The first command given at launch. The cable is only attached and then the slack remove by slowly winding inthe cable or moving the tug aircraft after the pilot has completed the pre-flight checks (CBSIFTCEB) and has ascertained that there are no other gliders in the way of the launch. Usually the decision to take up slack is made by the launch point controller, but if he/she can't see the winch cable clearly, a verbal or visual signal may be given by the wingtip holder. Find out how your club does things! Top

 

Thermal

A column or bubble of rising air caused by a warming of the ground. Rising air can be used to gain height, carrying the glider along with it. Gliding is a truly solar-powered sport! Dust devils and whirlwinds are extreme forms of thermals. Thermals can cause crop circles. (Crop circles are also formed by guys with ropes and boards, after a few drinks, usually after students pass their exams.) Top

 

Trailing edge

The back edge of the wing. The opposite of the leading edge. Do not push the glider around using the trailing edge. Top

 

Trim

A control which changes the neutral resting position of the stick in the forward/backward direction (controlling pitch), rather like a cruise control in a car. It allows a constant speed to be set without constant intervention by the pilot. This makes speed control very much easier. Depending on the glider, it either uses a system of springs connected to the control column, or a moveable tab on the elevator, effectively a little elevator on the elevator. Top

 

Undercarriage

The wheel the glider lands on. Modern racing gliders have a retractable undercarriage to make them more streamlined i.e. to reduce drag. Hang glider pilots use their own legs as the undercarriage, with the obvious unfortunate problems resulting from a poor landing. Top

 

Variometer (also known as the vario)

An instrument which tells you if you are gaining or losing height. It is VERY sensitive, and usually the most expensive instrument in the glider. Some have an audio output so that the pilot doesn't have to keep looking down at it to detect rising air. In a mechanical vario the air flowing into or out or a flask pushes the needle up or down. In an electric vario, the flow is detected electronically. In the vary latest varios, a pressure transducer calculates the heigth change and hence the rate of climb or sink. Electonic varios often have many other features built in to the microprocessor which calculates the rate of climb or sink, provides a gps powered moving map and directions on where your pre-programmed destination is located. These are the ones that cost the most. Top

 

Water

H₂O. Gliders carry water ballast in the wings (in tanks or rubber bags) to make them heavier. A heavy glider has to fly faster to generate enough lift to fly. It surprises some people that this can improve the glider's performance. Imagine a table tennis ball, a wooden ball and a steel ball, all the same size. Place them on a slope and watch them roll down it. They have moved the same distance forward for the same loss of height, but the densest one got there first. It's the same with gliders. Top

 

Weak Link

A piece of deliberately weaken metal which forms part of the winch cable or tow rope attachment. This will break if too much stress is applied during the launch. It saves the cable and the airframe of the glider from stress. Usually a steel strip with a precisely sized hole drilled in it. Top

 

Winch Launch

A 6 litre engine with 1500 m of steel or Dyneema cable is all that's needed to make your dream of flight come true. The cable is attached to the C of G hook of the glider which is then wound in at approximately 55-60 mph towards the winch, sited at the other end of the airfield. You climb like a kite at an angle of approximately 45 degrees. Winch launcing is very much cheaper than aerotowing, but you don't usually get as high initially, typically 900-1400', depending on the wind strength and runway length. But if you can find a thermal and soar, you can get away. And if there aren't any thermals, why would you pay good money for an aerotow? Top

 

WULF

Pre-circuit checks made just before entering the circuit pattern: -

• Water gone: (water is carried by some gliders),
• Undercarriage down and locked,
• Loose articles check (includes straps). Also check the Landing area, and Look out,
• Flaps correctly set for normal flight. During the later stages of the circuit, they will be adjusted again.
  
  There are several variations on the pre-circuit checks, the BGA doesn't enforce any one standard set at present. Top

Yaw

Movement, controlled by the rudder, around the vertical axis down through the centre of gravity. Basically the nose swings from side to side. Yes, a glider can be flown sideways, but it produces lots of drag which, as we all know, is inefficient and a bad thing. Top

NOTE: The compiler of this glossary accepts no responsibility for the accuracy of the information contained herein. All of this information should be discussed with your own instructors, who can help straighten out any mis-interpretations you may make. Reading this is NO SUBSTITUE for proper instruction, just an aid. Some of these definitions have been gathered from other web sites and then altered and improved at intervals.
Note also that this page was first created in the early days of the internet and is not built using modern design techniques. But one day it will be. Top