Frequently Asked Questions about Gliding
What is gliding?
For some, it is a casual hobby, and a way to meet new people. For others, it is an inexpensive way to get airborne. For many, it is the cutting edge sport of racing or aerobatics. For all, it is a silent and graceful way of flying without an engine.
What are gliders made from?
Also known as sailplanes, gliders come in many shapes and sizes and are made from a variety of materials. Modern gliders are typically fibreglass and other fibres such as carbon fibre and Kevlar. Older gliders are made from wood, fabric and/or metal.
Is flying a glider difficult?
No. You need to be able to use your hands and feet simultaneously to do different things and to interpret your surroundings and react accordingly. The basic skills that we use to drive a car or ride a motorbike demonstrate these skills.
What weather can you glide in?
Any weather except low cloud, rain and very strong wind.
What happens when the wind stops?
Nothing – gliders don’t need any wind to fly; they simply glide back to earth.
How many can fit in a glider?
Each club will have a two seat glider for training and a range of single seaters to progress into.
For a glider to fly it must first be ‘launched’ to a starting height. In order to launch, you generally need assistance – there are also self-launching gliders.
The aerotow launch involves being pulled up by a light-aircraft with a strong rope in between. When the glider gets to the required height, the glider pilot releases the rope, and the glider is free.
Winch launching is more exhilarating, but not as common as it used to be. This involves being attached to a powerful winch with a long reel of wire or rope. When the wire is reeled in, the glider gets the speed to fly into the air like a kite. When you are almost overhead the winch, you release the cable.
How do gliders keep flying without an engine?
Have you ever seen a flock of pelicans circling high in the sky or a seagull hovering motionless over a headland? The pelicans are flying in a column of rising air (a thermal) and the seagull is flying in the rising air deflected upwards by the cliff face (ridge lift). In both cases, the birds are in an air mass that is rising faster than they are descending through it. Gliders exploit the same natural phenomena.
How does a glider fly?
Just like a paper aeroplane once it is given some initial height, the glider flies by converting height into forward speed – it glides towards the ground.
Modern gliders have such good aerodynamics that it takes quite some time to glide down. Typical sink rates may be as low as 0.5 metre per second or less, so the descent from 1,000 metres could take 2,000 seconds. That’s over half an hour from a little over 3,000 feet. During that half hour, you may have travelled 50 km – all with no engine.
Whilst the glider slowly descends, an experienced pilot may be able to find air that is rising and carefully manoeuvre the glider so that it can regain height, ready for another glide. This is ‘soaring’.
Once you are airborne, how do you stay up? This depends on finding air that is rising. There are three forms of ‘lift’ – thermals, ridge (or hill) lift and wave. All are caused, one way or another, by the action of the sun shining on the earth.
How long can you stay up?
This depends on weather. On some days there is no rising air to be found, so your flight can only be a gentle glide back to earth – this will take around 10 – 20 minutes. When there is rising air to be found, flights of 5 hours or more are commonplace.
How high can you go?
On a typical flight you will release from the launch at around 2,000 feet. After that you may rise to 10,000 feet. The current world height record is around the 50,000 foot mark – that’s higher than a jet airliner’s cruise altitude. Heights above 10,000′ require supplemental oxygen.
How far can you go?
On poor soaring days you will be restricted to within glide range of the airfield. On good days, once you are competent, you can attempt recognised flights of 50km, 300km, 500km or 1,000km. The straight glide performance of gliders varies immensely. A modern high performance competition glider may glide 60km for every kilometre of height. A typical lower performance club glider will easily glide 10km for each 1,000′ without assistance from any rising air.
Once you know you can stay up (given the right conditions), you can use this to go places or ‘cross-country. Normally, this involves using one or all three forms of lift to get height, and then using this height to go forward to the next point on task (or to the next area of lift). A typical task may be a 300km triangle, with the aim to get back to where you started. On most weekends in the warmer months, glider pilots soar for many hours, touring over some beautiful countryside for many kilometres.
How fast can you fly?
Typically gliders fly at 50 – 70 knots (around 90 – 135 kph) between thermals. When circling in lift, the speed may be as little as 40 knots (70 kph). The highest speed that gliders typically can fly is 135 knots (250 kph).
What is ‘soaring’?
Soaring and gliding are used to describe the same thing. To soar means that the aircraft (or bird) is able to use naturally occurring air currents to maintain or gain height. All gliders gently descend through the air – if a glider is ‘falling’ through the air at a rate of 0.5 metres per second, then it only has to encounter an air mass rising at the same rate in order to maintain height. A strong thermal may be rising at 5 metres per second or more, so the net result will be a gain in height.
Once sufficient height has been gained, this potential energy can be traded for kinetic energy in the form of speed. So the aircraft glides in a relatively straight line to the next patch of rising air.
Where does rising air come from?
There are essentially 3 forms of ‘lift’: thermal, ridge and wave.
Thermal or convective lift
Natural sunshine is unable to heat air very effectively – the sun’s rays simply pass through it. When the sun shines on a patch of ground however, the ground very quickly warms up. This hot patch of ground then reflects its energy in a form that is able to heat the air above. Before long, a large pool of warm air is built up that eventually becomes buoyant enough to start to rise. This is the birth of a thermal and this mass of air may continue to rise for many thousands of feet until it cools to the same temperature as the surrounding air. This mass of air may also be many hundreds of metres across, easily big enough for a glider to circle in.
Ridge lift – Ridge lift is caused by a steady wind blowing against an obstacle such as a cliff face. The obstacle forces the wind to deflect upwards and once positioned in the midst of this rising air, then you can remain airborne for as long as the wind blows. In the early days of gliding, it was commonplace to attempt to set ever-increasing endurance records; these are no longer recognised because the pilots were literally falling asleep after many days without rest.
Wave lift – Perhaps the most revered form of lift is the magic of wave. Wave lift is a little difficult to imagine, but if you have seen a fast flowing creek with a boulder beneath the surface then you may have noticed that the water bulges up without cresting or breaking, forming a standing wave above the obstruction. There may also be trailing waves downstream that are positioned relative to the speed of the water flow and the position of the obstruction.
A similar thing occurs in the atmosphere when a steady wind blows against a mountain range. In this case though, the air may be forced to rise tens of thousands of feet into the atmosphere. At some point far downwind the rising air will start to descend until it ‘bounces’ back up again off the ground. If this point coincides with another mountain, then the subsequent peak of the second wave may be much higher that the first. This may go on to generate a number of tertiary waves hundreds of kilometres downwind of the original mountain.
Gliders can also execute a wide range of aerobatic figures. The obvious difference from aerobatics in a powered aircraft is that the glider pilot must use speed gained by diving to perform the chosen manoeuvre. When viewed from the ground, a glider gracefully performing silent aerobatics is always impressive.
Just having fun
If you take up gliding, you may be content to just fly yourself or your friends in lazy circles above the airfield; you don’t have to become a competition pilot or an aerobatic ace. You may want to contribute to the club by learning how to maintain the fleet by gaining some airworthiness qualifications, or you may enjoy the challenge of teaching others to fly by becoming an instructor, a rewarding volunteer role. Some say gliding is a bit like golf. There is always some aspect of your game that can be improved, whether it is getting the most efficient climb from each thermal or just performing consistently smooth landings.
How much does a glider cost?
Glider costs vary greatly. Technology has brought huge gains over the last few decades, but this comes at a price. For the latest two seat self-launching high-performance glider from Europe you could pay upwards of $300,000. At the other end of the scale is a well used or even vintage glider for a few thousand dollars. A typical second-hand glider with modest performance costs $20,000 – $50,000. Syndicating is a popular method of reducing the individual costs.
You don’t need to buy your own glider – clubs and commercial organisations have gliders for hire at very low rates. Most also have two-seaters for instructional purposes, or for sharing the excitement with friends, and most also have single-seaters which you move into once you are sent solo. If you do buy your own glider, you can keep the cost down by joining a syndicate.
Can you take gliders apart?
Gliders are designed specifically to be disassembled so that they can be stored in weatherproof trailers and towed by road between airfields. This also allows you to land in a paddock far from home and contact your retrieve crew to pick you up – called an outlanding, and considered a normal part of gliding.
How safe is gliding?
Gliding is not without risks; however these risks are reduced to a large degree by good training. Australia’s gliding safety record is amongst the best in the world.
What are the differences in glider classes?
Club class gliders are generally lower performance and operate under a handicap system to allow all types of gliders to compete together and be scored fairly.
Open class is just that – no restrictions on performance-increasing devices; open class generally involves longer wing spans.
Standard class gliders do not have flaps.
18m is limited to a maximum of 18m wing span – no other limitations apply.
15m is limited to 15m wing span – no other limitations apply.
How much does gliding cost?
Costs vary from club to club. Some offer a full commercial service and are priced accordingly, whilst others operate under a very strong club atmosphere to keep costs down. One of the major variables in the cost of learning is your own aptitude. Some people learn faster than others, though this does not mean that they will necessarily be ‘better’ pilots. Here are some rough guides:
A trial lesson with a typical club costs from around $75 – $100.
A 5 day ‘go for solo’ course will cost from $1,400.
Annual club membership including compulsory membership of the Gliding Federation of Australia (GFA) is $300 – $400.
Once a club member, you pay as you go. Glider time is charged by the minute; cost per minute varies from 30 to 60 cents. Some clubs offer a reducing rate for each subsequent hour of flight to encourage cross country flights.
Do I have to join a club?
Yes. If you choose to take a trial lesson then you automatically take out a 3 day membership of the GFA included in the price. If you choose to continue, then you need to become a financial member of the GFA and an affiliated gliding club.
Where is my nearest club?
There are over 80 gliding clubs throughout Australia. The largest clubs are typically close to capital cities, but even some remote areas have gliding clubs nearby.
Can I buy a flight as a gift?
Yes. Most clubs offer an option to purchase a gift voucher for a trial flight.
For further information: http://www.gfa.org.au