$9 AIRFARES

Glider Flying Handbook

For certified glider pilots and students preparing for certification in the glider category, this book—prepared by the Federal Aviation Administration—is a resource without equal. Covering components and systems, flight instruments, performance limitations, preflight and ground operations, launch and recovery procedures, flight maneuvers, traffic patterns, soaring weather, radio navigation, and much more, it lays out in authoritative detail the science, mechanics, and regulations that every pilot needs to know. Plus, it contains a glossary of essential terms and crystal-clear color illustrations. No one should learn to fly, or fly a glider, without this information close at hand.

Gliding and soaring gained popularity in the United States from the early 1930s through the postwar years but the difficulties of getting a glider airborne put off many potential enthusiasts. Glider pilots had a variety of options available but all were relatively cumbersome and sometimes dangerous, and required other pilots, drivers, or ground personnel. The most convenient method was to take off in tow behind either an automobile or a powered aircraft. When gliding and soaring began in Germany shortly after World War I, groups of healthy people ran down hills and towed the motor-less aircraft into the air attached to elastic 'bungee' chords. Bungee launches were very popular in Europe but the wider availability of auto and airplane tows, and the hot and humid weather in North America, prevented this labor-intensive alternative from migrating to the New World. Powered winches also pulled gliders aloft but this technique could be risky and required a certain degree of pilot skill. It also demanded a skilled winch operator.

Once aloft, a pilot might elect to boldly depart the vicinity of the airport and proceed cross-country. The result was usually an offsite landing in a meadow or farm field. To return the aircraft to the home base required another considerable expenditure of group labor. A ground crew first disassembled the glider into manageable sections, then loaded the pieces aboard a special glider trailer and hauled them back by road. Glider enthusiasts spent more time preparing to fly, rather than actually flying, than any other group in aviation. The solution to this imbalance between fun and work was to motorize the glider and allow the pilot to self-launch. This idea appeared simple in theory but it proved more complicated in practice.

A prospective designer of a practical motor glider had to overcome three obstacles. He first had to select a proper power plant. It must be strong enough to propel pilot and aircraft off the ground to altitudes high enough for safe soaring, yet not so powerful that the weight and size of the engine substantially subtracted from the glide-ratio. The second problem lay in streamlining the propeller and motor to reduce drag once the pilot silenced the engine and began to glide.

Glider enthusiasts in Germany first experimented with powered gliders during the early 1920s. Karl Plauth designed the two-seat D 8 "Karl der Grosse" in 1923. In the United States, William H. Bowlus and Ted Nelson built one of the first self-launching motorgliders in the United States. Bowlus had established himself as a master-craftsman in glider design and construction during the 1930s with two designs, the Bowlus BA-100 Baby Albatross and Senior Albatross (see NASM collection for both aircraft). Nelson had developed several of his own designs during the same period. In 1945, Bowlus and Nelson formed the Nelson Aircraft Corporation to build a two-seat, motor glider version of the popular Bowlus BA-100 Baby Albatross. The designers nicknamed this design the Bumblebee but they sold the powered glider under the official moniker, Dragonfly.

The men retained the basic Baby Albatross design but significantly widened the cockpit and added side-by-side seating and flight controls for each occupant. Other improvements included tricycle landing gear and a steerable nose landing gear, additional vertical fins mounted on the ends of the horizontal stabilizer, and a hinged canopy. A handle to pull-start the engine was also available inside the cockpit. The aft section of the fuselage pod on the Baby Albatross was an ideal place to install a pusher engine and propeller. Bowlus and Nelson first selected a Ryder four-cylinder, two-cycle power plant but this engine only managed to produce about 16 horsepower. This was not enough power for flight so Nelson decided to build a suitable engine from scratch. His new motor generated 25 horsepower, barely enough to takeoff and slowly climb.

The low-horsepower engines could only turn small, lightweight propellers, but this was acceptable because larger propellers added weight and drag. On the downside, the smaller propellers had to rotate at very high revolutions-per-minute (rpm) to generate sufficient thrust. Nelson's engine had to turn 3,900 rpm to get the Dragonfly off the ground. The small diameter propeller that turned at a high rpm level was considerably less efficient than larger propellers turning at lower rpm.

This combination of power plant and propeller allowed the Dragonfly to climb 235 feet per minute at sea level. The extra weight of the engine, plus the drag from the widened fuselage, gave the Dragonfly a mediocre lift-to-drag ratio. The self-launch capability cost too much performance to appeal to most prospective motorglider owners and Bowlus and Nelson only sold seven Dragonflys. Nelson attempted to design another self-launching glider in 1949 but this time, he teamed with Harry Perl. Don Mitchell also helped on the new airplane. Nels

Test pilots at Grob-Werke GmbH & Company KG in Germany first flew the Grob 102 Standard Astir III late in 1980. The Standard Astir III is one of several models that Grob has designed specifically to conform to the international Standard Class category of competitive sailplanes adopted in 1958. The community of European glider pilots devised this category to encourage sailplane manufacturers and sport pilots to build and fly relatively inexpensive sailplanes. The glider had also to appeal to glider flying clubs and handle easily in the air. Those who created the class also hoped to give pilots from smaller countries a venue in which they could compete fairly with pilots from larger, wealthier countries. A Standard Class sailplane must have a 15-m (49.2-foot) wingspan, fixed landing gear, and no flaps. For years, many pilots and competition officials disputed the Standard Class definition and the United States did not recognize it until 1969.

Pilots liked the large roomy cockpit on the Standard Astir III. They could fly the sailplane at its best glide ratio, 38:1, at a speed of 105 km/h (65 mph), and then accelerate to the maximum speed, 250 km/h (155 mph), or slow to the stall speed, 60 km/h (38 mph).

In 1978, Robert Harris first rode a sailplane into the sky and the experience enthralled him. Harris set about breaking the world glider altitude record after he discovered that no one had bested the mark that Paul Bickle had set on February 21, 1961, when he reached 14,065 m (46,267 ft).

To prepare for an attempt at the record, Harris spent five years working his way ever higher. First, he soared to 6,080 m (20,000 ft) and then 10,640 m (35,000 ft). Twice he topped 11,552 m (38,000 ft) and during the spring of 1985, he reached 12,160 m (40,000 ft). Harris made all of these flights after taking off from an airport near the town of Independence in the Owens Valley region of central California and soaring above the mighty Sierra Nevada Mountains. Shortly before 1 p.m. on February 17, 1986, a tow plane hauled Harris and the Grob 102 Standard Astir III aloft. He unhooked the towline and soon found weak lift that he worked to an altitude of 10,640 m (35,000 ft). Strong lift then pushed the glider up at 182-243 m (600-800 ft) per minute. By the time he had reached 11,552 m (38,000 ft), frost completely covered the canopy and Harris began to fly solely by reference to his instruments. At 12,768 m (42,000 ft), his eyes began to water but the teardrops froze and immediately formed ice cobwebs. Even five layers of clothing could not insulate him from temperatures that dropped to minus 65-70 degrees F (-50 degrees Centigrade) inside the cockpit. A failing oxygen system forced him to stop his record climb at 14,899 m (49,009 ft) and he returned triumphantly to earth using backup oxygen.

Many applauded Harris's achievement but the Federal Aviation Administration criticized the pilot for flying in controlled airspace without permission. On June 4, 1997, Robert Harris and his wife, Susan Rothermund, donated their Standard Astir III to the National Air and Space Museum.

The Soaring Pilot's Manual advances the reader from elementary flying to confident soaring by clearly and precisely explaining the basic soaring mechanisms and techniques. Explanatory diagrams illustrate the text throughout, making a complicated subject simple to understand. Having covered the first steps, the book progresses to cross-country flying and the final section contains exercises that will be found useful for any glider pilot wishing to improve his ability and qualifications. The latest technology, such as GPS navigation and instrument systems is covered.