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About Soaring
A Brief History of Soaring
The sleek high performance sailplanes of today have a heritage that dates back to man's first attempts at flight. History tends to move from simple to complex and aviation follows this premise elegantly. With no understanding of aerodynamics, few adequate materials and no available engines, avation enthusiasts had to be content with using crude gliders using the force of gravity and a slope to become airborne. These flights were short and often ended in a less than elegant arrival, but it was flying nonetheless.
In the early 1900's the famed Wright Brothers experimented with gliders and gliding flight in the hills of Kitty Hawk, North Carolina. The Wrights developed a series of gliders while experimenting with aerodynamics. This was crucial to developing a workable control system. Many historians and, most importantly, the Wrights themselves pointed out that their plan was to learn flight control and become pilots specifically by soaring, whereas other experimenters rushed to add power without refining flight control. By 1903 Orville and Wilbur Wright had achieved powered flight of just over a minute by putting an engine on their best glider design.
How Gliders Go Up
Aero tow is the most widely used method of getting a glider airborne in the U.S. today. The sailplane is pulled aloft by a 200 foot nylon or polypropylene rope secured by a special hook to the tow plane. The sailplane pilot can release the tow rope at any altitude desired. In the unlikely event of a sailplane release mechanism malfunction, the tow plane pilot can release the tow line. Once the glider has released, the tow-plane returns to the airport with the tow rope streaming behind.
Auto launches are sometimes used. A 1000 foot rope connects the sailplane to a special hook on the towing automobile. When the signal is given, the tow vehicle drives down the launch runway and the glider pilot flies the glider up to an altitude of 800 feet or so, then releases the tow line which falls gently to earth. This method is commonly used when the airstrip sits atop a large hill or mountain.[1]
Gliders are often launched using a stationary ground-based winch mounted on a heavy vehicle. This method is widely used at many European clubs, often in addition to aerotowing. The engine is usually a large diesel, though hydraulic fluid engines and electrical motors are also used. The winch pulls in a 3,000 to 5,500-foot cable, made of high-tensile steel wire or a synthetic fiber, attached to the glider. The cable is released at a height of about 1,300 to 2,200 feet after a short and steep ride.[2]
Auto and winch launches are less expensive than aerotows; however, to conduct them safely, they do require a several member crew.
How Gliders Stay Up
It's easy for the slender sailplane to stay aloft without an engine, since it is aerodynamically designed to glide efficiently through the air. Gravity slowly draws it toward the earth's surface. Generally, a 20-25 minute flight will result after the sailplane releases from a 3000 foot aero tow, when no rising air currents are found to extend the flight.
The pilot in the sailplane can achieve a longer flight if the air mass in which he is flying is rising at a faster rate than the sailplane is gliding downward. When this happens, the real thrill of flying without an engine begins! The most common sources of lift are thermal lift, ridge or slope lift, and wave lift.
Thermal lift is the most common form of lift. Thermal lift is dependent upon solar energy. The earth, when heated by the sun, warms the air next to it, causing it to expand and rise just like steam coming from a boiling kettle. Bubbles of warm, rising air form into columns called thermals. Some terrain absorbs heat from the sun more rapidly than the surrounding earth. Dark plowed fields, asphalt parking lots and rocky terrain absorb the sun's heat quickly and provide excellent sources of lift. Open countryside and desert lands are also known for their strong thermals. In some areas of the United States, sailplanes have ridden thermals up to altitudes of 25,000 feet!
Thermals are frequently topped by cumulus clouds that form as the heated air cools and the moisture it contains condenses. Sometimes, however, thermals can occur when the sky is completely blue. The first "blue" thermal was flown by Wolf Hirth during the first U.S. National Glider Meet, flying from Elmira to Appalachian, NY.
Ridge lift is dependent upon wind. When the wind blows against a mountain, hill, cliff, or ridge line, the air flow is deflected upward and, depending on the strength of the wind, can rise hundreds of feet above the top of the ridge. Sailplanes can fly back and forth for hours on the narrow band of rising air on the upwind side of the ridge. Flights of more than 1,000 miles have been made using ridge lift along mountain chains.
Mountain wave flying is especially exciting to many glider pilots. This meteorological phenomenon occurs when strong winds (more than 25 mph) blow perpendicular to a mountain or ridge. The wind flows over the top of the obstruction and down the opposite side, where it bounces off a layer of stable air near the ground and is deflected upward many thousands of feet to another layer of stable air where it bounces downward again. This wave action can occur many times in succession and is very similar to what you see when water flows over a submerged log in a stream. Sailplanes can rise at 2,000 feet per minute or more in the rising air on the upwind side of each wave. Wave flights can reach altitudes of 35,000 feet or more. At these altitudes, supplemental breathing oxygen and other precautions are necessary.
By the late 1900s aviation became common place with jet travel being critical to the world economy. Soaring has grown into a diverse and interesting sport. Modern high performance sailplanes are made from composite materials and take advantage of highly refined aerodynamics and control systems. Soaring pilots use sophisticated instrumentation including global positioning satellites (GPS) and electronic glide computers to go further, faster and higher than ever before.
Modern Soaring
Advances in technology and a better understanding of nature's atmospheric forces have made soaring a safe and enjoyable activity for an estimated 150,000 glider pilots worldwide. Although a majority of these pilots are in european countries where gliding first gained popularity, the sport has gained international attention.
There are over 180 soaring clubs in the U.S., with one located near almost every large city. Soaring clubs take many forms and some have enrollments of 200+ members. Clubs distribute the cost of equipment and instruction, offering inexpensive access to the sport. They normally own several gliders and towplanes for use by their members and many offer rides and instruction at a very reasonable cost. Clubs provide nearly 40,000 licensed glider pilots in the U.S. a relaxing way to enjoy the sport. Over 5,000 sailplanes are currently registered in the U.S.
There are over 80 commercial soaring operations in the U.S. offering rides, flight training and rental services.
While there are many ways to enjoy soaring, from a lazy summer afternoon of relaxing local flying to more energetic cross country flying, it is competitive soaring that provides the ultimate test of pilot grit and skill. Competitive soaring in the U.S. is organized by the Soaring Society of America (SSA). There are regional and national contests held each year with top pilots flying several events each season.[1]
More Information
Please visit Soaring Society of America's website for more information on soaring.