for the flow of air over the sur face of its wing. If the flow is fast enough, it will fly, if not, it will stall and descend vertically. What is happening in the air only A F®w IHI@lillIr~ a few feet away is of no concern, far less what is happening at the earth's surface below. Insofar as ©~ [))©lyllii!lffitt the glider is concerned, it is al ways descending at a constant rate J. S. Brennan for any given airspeed, and that airspeed is measured only by the rate of flow of the air over its wing. But what if a wind is blowing? Wind is assume<;l here to be a Articles on the sport of soar "gliding" bears a connotation of horizontal flow of air with respect ing, or motorless flight, are of descending, and "soaring" of as to the fixed earth. The glider, iso many kinds, ranging from the cending. Common usage also dis lated in its immediately surround highly technical to the highly tinguishes between a "glider" as ing air, is not concerned with the aesthetic, from low-speed aero being a motorless aircraft of low wind. The fact that the mass of dynamics to Jonathan Living performance, and a "sailplane" as air, through which the glider is stone Seagull. This article ad being one of high performance. flying at its constant airspeed and dresses the basic mechanics of We speak more of "performance" rate of descent, is moving with soaring, the weather conditions later. respect to the ground has abso and phenomena which permit Influence of Wind lutely no effect on the flight con soaring flight, but not the tech ditions of the glider. The pilot nique of flying a sailplane. It It is not difficult to accept the may be concerned that his path attempts to supply sufficient in fact that a motorless aircraft, be over the ground is modified by formation for the reader to gain it glider or sailplane, in stilI air wind-induced drift, or that his a reasonable comprehension not will be constantly descending. So speed over the ground is increased only of the sources of energy long as it is unaffected by out or decreased by wind components, which permit soaring, but, by way side influences, the glider will be but this is a matter of navigation, of fallout, an appreciation of converting the potential energy and has nothing to do with flight what the sport is all about. Hope of altitude into the kinetic energy performance. fully it will convey to the reader of forward motion, through which awareness of the fallacy con aerodynamic lift is generated to Vertical Flow of Air tained in the often-heard ques sustain the glider in flight, while tion, "Why did you land, did the some portion of the energy is Instead of the horizontal mo wind quit?" dissipated to the surrounding air tion of the atmosphere which we Throughout this article the through aerodynamic drag. Un call wind, let us stipulate the ex terms "gliding" and "soaring" will less energy is added to the sys istence of vertical motion. Vertical be used without precise distinc tem, the glider will eventually motion necessarily entails both up tion, although in common usage exp~nd all of its altitude and must ward and downward flow, so that land. In the case of a powered the general mass distribution of the J . S. Brennan, author of "A Few Hours aircraft, energy is continually atmosphere is maintained. Ignor of Daylight," was born in Utica, N.Y. He being fed into the system by the ing for the moment what might be received a B.S. degree in Optics from the the source of such vertical cur University of Rochester in 1943, and a engine. The glider must extract Juris Doctor degree from Georgetown Uni its energy from its natural sur rents of air, we can accept the versity in 1951. Since joining APL in 1965, roundings. The rate of this energy fact that a glider, flying in a mass Mr. Brennan served for several years as Acting Head of the Budget Office and is extraction is a function of the of air which is rising at a speed now the Administrator for Grants and Con existing meteorological conditions greater than the natural descend tracts. His interest in aviation was evident and of the skill of the pilot. ing speed of the glider, will gain at an early age, and he learn"ed to fly powered .aircraft in 1944. He received his The glider is extremely self altitude. These rising currents of private license in gliders in 1960, and has centered. It will fly straight or air are generically called "lift," been an active member of the Mid-Atlantic Soaring Association based in Frederick, turn, fly fast or slowly at the be while the accompanying down Maryland, since 1962. hest of the pilot, but it cares only ward currents are called "sink."
Volume 12, Number 3 11 Depending on the nature of the knots or more at the crest of the meteorological phenomenon which ~::=~===- ridge, and increasing with alti gives rise to the currents, the tech tude; and (c) the existence of a nique of extracting its energy, that stable layer (e.g. a temperature is, the pattern of flight, will differ. inversion) in the atmosphere sep The pilot's task is to remain in arating layers of low stability the lift until he has reached some above and below. desired altitude, and then to ex Schematically the flow pattern pend the altitude in straight flight which accompanies the wave is along his intended path. shown in Fig. 2. While the wave The vertical currents can result pattern is stationary with respect from a number of naturally oc to the ridge, the air is flowing curring conditions. The principal Fig. I-Air flow against an obstruction through it. Typically the horizon sources of such lift are known as resulting in the generation of ridge lift. tal component of the flow at "ridge lift," "mountain wave," some altitude above the crest of and "thermals." In addition, there Altitude is gained, or main the ridge will be near or above are coldfronts, shear lines, oro tained, in ridge lift by flying back the stalling speed of the glider. graphic thermals, anabatic winds, and forth across the face of the By flying into the wind, the pilot thermal wave, and all varieties terrain feature which causes it. can control his position with re of combinations of some of these Generally it is necessary to fly spect to the wave by changing his effects. Almost all soaring in this quite close to the face of the airspeed, or if the wind velocity country uses one or more of the slope to find the strongest lift, so is too low, he can tack back and first three named effects, and an that as a safety precaution, all forth at a small angle to the wind understanding of them will suffice turns are made away from the direction. for all practical purposes. slope. Rules of the road have been devised to minimize interference when more than one glider is ~15r------' Ridge Lift Ql involved. ~ Ridge lift is the simplest of the '0 three to understand. It is the re Lee Wave sult of a wind of some velocity, perhaps ten knots or more, blow Mountain wave, or lee wave as ing against the face of a sharp it is frequently called, provides an w o opportunity of flying to relatively ::J rise in the terrain, such as a cliff I- or a mountain ridge. Since the high altitudes. Like ridge lift, it is i= ....J air must rise to get over the ob generated by a wind blowing « struction, there is a vertical com nearly perpendicularly to a ridge, ponent to the wind flow, and it but it is found on the lee side of is this vertical component that the ridge in the form of a stand Fig. 2-Air flow over a mountain or ridge resulting in lee wave. provides the lift. The flow is ing wave. It can be visualized by shown diagrammatically in Fig. analogy to a log lying submerged 1. The location of the maximum across a stream. The water rises While it is possible under most lift will vary somewhat with the to cross the obstruction, falls on conditions to climb in any of the shape of the rise in the ground, the downstream side, and then upward flowing parts of the wave, with the velocity of the wind, and may rise and fall several more the greatest climb rate and peak with altitude. Characteristically it times before quiescent flow is altitude is usually found in the will be located along some line, again established. In a similar primary wave, i.e., the wave such as the line x-x' in the figure, fashion, under the appropriate closest to the ridge. If a glider and always on the upwind side conditions, a wave is formed in is introduced into the wave sys of the slope. Corresponding to the the air downwind from a ridge. tem at some point A in the figure, lift on the upwind side of a ridge, While the appropriate conditions the vertical component of the air there is nearly always sink on the are not precisely defined, they flow will permit the glider to downwind side at low altitudes. consist essentially of the follow ascend not only along the stream Ridge lift is usually associated ing: (a) wind direction nearly line, but also from one streamline with a terrain feature of some perpendicular to the length of the to another until some point B is length, although it might be found ridge, and nearly constant with reached, at which point the lift near an isolated hill. altitude; (b) wind velocity 25 ing component of the wave just
12 APL Technical Digest equals the natural sinking speed In the local area, wave usually rising air mass, with considerable of the glider. accompanies a post-frontal wind support for the thesis that an iso The wave is a fixed pattern in from the northwest or west, blow lated thermal is a vortex ring, the atmosphere with a stream of ing across the ridges of the Ap similar to a smoke ring, but rising air flowing through it. If the palachians. There are a number vertically as shown in Fig. 4. stream of air is moist and the of these ridges generally parallel Since the upward velocity of the amplitude of the wave sufficient, to each other, with varying spac airflow is greater at the center of the moisture will be carried above ings. Depending on wind direc the thermal than the upward vel its dew point and will form a tion and velocity, the several wave ocity of the thermal itself, it is cloud of characteristic shape. The systems may become superim theorized that it is possible to cloud appears to remain station posed and generate an interfer climb through the thermal struc ary like the wave, although in ence pattern of extraordinary ture as it rises. fact it is constantly being dissi complexity. The glider pilot, when pated on the downwind edge and such conditions occur, has to regenerated on the upwind edge. abandon the book and exercise The flow of air brings the mois his own knowledge, ingenuity, and ture in the air to the level at which just plain luck. the dew point occurs, then the wave starts to descend after its Lapse Rate and Thermals peak and carries cloud particles to a level where the temperature The most ubiquitous source of is above the dew point and the altitude gain used by the soaring water is again evaporated. If the pilot is the thermal. In simplest wave is simple in structure, the terms a thermal is a mass of air, process will produce long parallel buoyant with respect to its sur "loaves" of cloud, called lenticu roundings, which rises from lars or lennies from their lens ground level to an altitude deter shape in cross-section. A classic mined by the existing meterologi formation of this type is shown cal conditions. There is some in Fig. 3, taken from a roof-top disagreement among the pundits in Washington, D. C. as to the exact structure of the Fig. 4-Schematic representation of flow in a vortex ring believed to be typical of that in isolated thermals.
The buoyancy of the thermal with respect to its surroundings is due to either an excess of tem perature or an excess of moisture, or perhaps both. A mixture of dry air and water vapor is less dense than dry air alone at the same temperature. Thermals cooler than their surrounding air mass have been observed on many occasions near the sea coast, but almost all inland ther mals are warmer than the sur rounding air mass. While the air in our atmos phere is light, its weight is by no means negligible. The column of air over each square foot of the earth's surface weighs about one
Official photograph, National Oceanic aAd Atmospheric Administration. ton. Since the top parts of the col umn are supported by the lower, Fig. 3-lenticular cloud formations resulting from lee waves over Washington, D.C. there must exist a pressure gra-
Volume 12, Number 3 13 dient with altitude. In the Stan dard Atmosphere the pressure at 18,000 feet is just half that at sea level. If a parcel of dry air at sea level were in some manner raised adiabatically, without gain or loss of heat, to some higher level, it would expand and cool. The rate of reduction in tempera ture with altitude is called the lapse rate. In this case the reduc tion is called the dry adiabatic lapse rate, and it has the value of about 3°C per 1,000 feet. If a parcel of saturated air is simi larly raised it will cool at a dif ferent rate, called the moist adia batic lapse rate, which varies from about 1.1°C to 2.8°C per 1,000 feet, depending on its tempera ture. The lower values for the Official photograph, National Oceanic and Atmospheric Administration. moist lapse rate result from the Fig. 6--Cumulus clouds characteristic of good soaring conditions. absorption of heat released by the condensation of the moisture as then the air is absolutely unstable, point the decreasing trend of the air is reduced in temperature. regardless of the amount of mois temperature ceases or is reversed, When the actual lapse rate is ture it might contain, and any par and for a few hundreds of feet less than the moist adiabatic lapse cel of air lifted from its initial the air temperature may increase rate, the air is stable, regardless level will continue to rise when with altitude. When the thermal of the amount of moisture it con the lifting force is removed. reaches this altitude the marginal tains. In Fig. 5 if the actual lapse When the actual lapse rate lies temperature difference between it rate lies to the right of the moist between the dry and the moist and its surroundings may disap adiabat, then a parcel of air which adiabats, then the air will be con pear and the thermal "tops out," is lifted to a higher level becomes ditionally stable. If the air is and no further gain in altitude cooler than its surroundings and saturated, it will be unstable, if is possible. falls back to its original level unsaturated it will be stable. The air at ground level is usu when the lifting force is removed. The warmth of the air which ally more moist than the air at If the actual lapse rate is comprises the thermal, from higher altitudes. As the thermal greater than the dry adiabatic which it gains its buoyancy, comes rises and cools, it frequently lapse rate, lying to the left of the initially from the absorption of reaches the dew point below the dry adiabat in the illustration, solar energy by the ground. The level of the inversion and the heated ground in turn warms the moisture condenses into cumulus layer of air lying above it. While clouds such as those shown in this air is then buoyant, surface Fig. 6. When the cloud is initially CONDITION ALL Y STABLE STABLE tension effects may hold it in formed it has a clearly-defined AIR place until additional heating or and flattened bottom surface and
UJ o a gust of wind releases it and it this persists so long as the ther ~ I- begins to rise. If, as is normal, the mal continues to add more moist f= air at higher altitudes is cooler air to it. When the thermal ....J « than at lower, the warmed air ceases, as it will when the supply UNSTABLE mass which constitutes the ther of heated air near the ground is AIR mal will find its surroundings con exhausted, the bottom of the tinually cooler as it rises, which cloud loses its flatness and takes O ~ ______~~--....l preserves its buoyancy. on a more fuzzy appearance. In o TEMPERATURE At some altitude, usually from its later stages there may be sug 3,000 to 7,000 feet in the eastern gestions of hanging tendrils of Fig. 5-The degree of stability of the air as a function of the temperature United States, a temperature in mist, by which time there may be change with altitude. version frequently occurs. At this sink instead of lift below the
14 APL Technical Digest cloud. If the atmosphere is gener heat from the surface of the scribed in terms that permit visu ally dry, the cloud will gradually ground into space. alization of neat symmetrical col disappear with a life-cycle time After sunrise the absorption of umns of upward-flowing air, in real of about half an hour. solar radiation warms the ground life they, like so many things in Since the lapse rate determines and the overlying stratum of air, nature, are of infinite variety. whether thermals of the height and some hours after sunrise a Radar observations made by APL and velocity of interest to the sounding would show the situa staff members, under the direc soaring pilot will occur, it is an tion of Fig. 7 (b). The nocturnal tion of T. G. Konrad and Isadore essential ingredient in a soaring inversion has been eliminated by Katz, have made it possible to forecast. The graph of tempera insolation and has been replaced observe both the structure of in ture against altitude is termed a by a superadiabatic layer some dividual thermals and the struc "sounding." While the data are tens of feet in depth. The super ture of fields of convection, and available from the Weather Ser adiabatic layer is absolutely un so to investigate their spatial and vice from early morning radio stable and hence forms a breed temporal characteristics. The ther sonde transmissions, it is not a ing ground for thermals. Whether mals are made visible to the radar difficult do-it-yourself project the thermals which are born with through backscattering from ir using a powered airplane. in this layer grow to proportions regular, small-scale fluctuations in The typical fair-weather early of interest to the soaring pilot the radar refractive index caused morning sounding in summer has depends on the lapse rate above by turbulent mixing. The fluctua the appearance of Fig. 7 (a). The the layer. tions are in turn caused by varia temperature increases with alti Thermals are the most fre tions in the physical properties tude for the first few hundred quently used source of lift both of the air, chiefly moisture con feet and then assumes the more for local soaring and for cross tent, and to a lesser extent, tem familiar decreasing trend until at country flights. They are some perature. Since the mixing occurs some altitude the persistent tem times of very limited diameter, at the interface between the rising perature inversion is encountered. and to extract the greatest amount air mass and the ambient sur The low level inversion results of energy in such cases it is neces roundings, the backscatter radar from the nocturnal radiation of sary to fly the glider in small signal outlines the outer shell of steeply banked circles. There is a the thermal, and only seldom trade-off situation between the gives indication of its internal sinking speed of the glider, which structuring. Limitations in the re increases with bank angle, and solving power of the radar tend the vertical velocity of the air to broaden the delineation of the w in the thermal, which decreases echoes on the radar screen, so o :::> with distance from the center. To that the rather thin shell of the I- i= fly in a circle of small radius the thermal is presented more in the ...J ~ bank must be steep, and the proportions of a doughnut, as small circle is usually needed to shown in the Plan Position Indi fly in the strongest lift. When cator (PPI) presentation of Fig. a sufficient altitude has been gained, S (a) as well as in the Range the pilot flies the glider in a Height Indicator (RHI) presen straight line in the direction of tation of Fig. S (b). These figures his intended flight, deviating, per show horizontal and vertical sec haps, in response to a promising tions respectively through the con w o cloud formation, circling again to vective field on the landward :::> I- regain height at intervals dictated side of Wallops Station, Virginia, i= ...J by his judgment. His path, then, using an S-band radar. It might ~ resembles a sawtooth, with verti be mentioned in passing that a cal climbs of from two to four glider pilot, seeing the thermal b thousand feet, and intervals be frequency depicted by these sam TEMPERATURE tween climbs of from three to ten ples, might be somewhat incredu miles, depending on the capabili lous, thinki_ng in terms of his own ties of the glider and the strength experience. Fig. 7-Schematic representations of of the thermals. soundings. (a) A typical early morning Figure 9 shows a variant of sounding in summer; (b) The sounding Convection as Seen by Radar modified by several hours of solar thermal development-"thermal heating. While thermals have been de- streeting." This preferential aJign-
Volume 12, Number 3 15 maximum advantage from the ordered arrangement of thermals. Conditions which encourage the formation of streets are the com bination of a lapse rate close to the dry adiabat, a significant tem perature inversion, and a wind of modest velocity, constant in direc tion with altitude, and increasing with height to some maximum, then decreasing with height while still within the convective layer. The existence of streeting is usu ally revealed by a corresponding organization of cumulus clouds.
Glider Performance On any given day with its ther mal strengths and frequencies, the distance or speed achieved by a soaring pilot will depend on the performance of his sailplane. Per formance is a somewhat nebulous term, but certainly includes the handling qualities of the ship in flight, which are reflected in pilot fatigue, and the maximum rate Fig. 8{a)-Thermals as seen on the PPI of an S-band radar. of roll, which affects his ability to rapidly center a thermal, but most of all it is flight capabilities shown by its "polar." The polar is a plot of the sink ing speed of the glider in still air as a function of its airspeed. A polar typical of a modern high performance glider is shown in Fig. 10. At the low-speed end the rapid increase in sinking speed results from flow separation at low speeds and high angles of at tack, culminating in a stall. At the other extreme the increase in airspeed causes a build-up in drag 5 10 15 RANGE (nmi) demonstrated as an increase in sinking speed in addition to that Fig. 8(b)-A convective field as seen on the RHI of an S-band radar. which would result merely from flying the glider in a nose-down ment along the wind direction course. Heavy sink is usually ex attitude to achieve the higher air permits soaring at relatively high perienced between the streets, so speed. The speed of minimum speeds in the down-wind direc that the technique includes flying sink is usually the optimum speed tion, since the increased frequency along a street, and then turning to fly when circling in a thermal of thermal encounter eliminates at right angles to cross to the next or when flying in any sort of weak the need to circle in lift. Airspeed street in the shortest possible time. lift, since this permits the maxi is decreased while in rising air By this means a course at some mum gain in altitude, and the and is increased between ther angle to the wind direction can tightest circle. mals, while maintaining a straight be achieved, while gaining the In aerodynamic terms "lift" is
16 APL Technical Digest day is limited. Since the air be tween thermals is not still, more efficient cruise can be maintained by increasing speed in strong sink and decreasing it where the air is still or the sink is mild. Both in the technique of getting the most out of each thermal and in the method of flying between thermals, the differences in soar ing skills among pilots of varying ability become apparent. High performance sailplanes, because of the laws of aerodynamics, bear a substantial similarity in appear ance to one another. Two classes of sailplanes are recognized in ternationally-the "open" class, with no restrictions, and the "standard" class, with wingspan limited to 15 meters and camber changing devices limited to fixed Fig. 9-Alignment of convective cells in the direction of the wind, known as hinge flaps. While separate world "thermal streeting," as seen on the PPI of an S·band radar. records are not maintained for the two classes, they are sepa rately scored in world competi o~------~ STANDARD LlBELLE tion and separate class champions are recognized. In the United Z 200 ~ States the Standard Class Na f::: u. tionals and the Open Class Na ~400 z tionals are two entirely different en events. A standard class sailplane ~ 600 w can be flown in open competition, I- but not vice versa. ~ 800 POLAR (CALCULATED FOR WING LOADING OF 5.9 LBS/SO FT) The main differences between the two classes lie in the ease 10000~-----2~0----~40~----~60------~----~------~----~1~ of assembly and disassembly, AI R SPEED (MPH) which is strongly weighted in fa vor of the standard ships, and Fig. 100The polar of a modern standard class glider. in the maximum attainable LI D, which is limited to about 38 in the standard class, while manufac the upward force, generated by the origin. The airspeed corre turers of open class ships, with the flow of air over the surface sponding to the point of tangency their wingspans as great as 23 of the wing, which sustains the will produce the best LI D in still meters, claim glide ratios as high weight of the glider and its pilot. air. as 54: 1. Skill and good fortune "Drag" is the horizontal force However, the best L/ D is not can, however, make up for this which opposes the forward move necessarily the best speed to fly. difference. In the 1972 Open Class ment of the glider through the If the thermals are strong, a Nationals, first place was won by resisting air. The ratio of lift to higher average speed can be a pilot flying a standard class sail drag (LI D) measures the for achieved by flying well above the plane. ward distance the glider can best L/ D speed, sacrificing some travel for each unit loss in alti altitude as a result, but gaining FAI Badge Program tude. The airspeed at which the time by the ability to climb To encourage achievement in maximum LI D will be achieved rapidly in the thermals. A higher soaring, the Federation Aero can be determined by construct speed equates to greater distances nautique Internationale, the Paris ing the tangent to the polar from since the length of the flyable based world body charged with
Volume 12, Number 3 17 overseeing all forms of sport avi and in pilot skills over the recent 1970 it was 717 miles, and in ation, including model aircraft past throughout the world. This 1972 Hans Werner Grosse, a records, issues a series of badges, has been reflected in a continual vastly respected German pilot, on for which the requirements are improvement in world records in an exceptional day flew from Lue the same throughout the world. various categories, with the beck, West Germany, on the Bal The A, B, and C badges are asso notable exception of the altitude tic coast, to Biarritz on the Bay ciated with the early stages of gain and absolute altitude marks. of Biscay near the Spanish flight training. They are followed These figures have remained un French border, for a new record by the Silver C, the Gold C, and changed since February of 1961 of 907.7 miles. the Diamond C. The requirements when Paul Bickle, then head of On the same day and in the for each of the three highest NASA's flight test group at Ed same geographic area, Klaus badges are as follows: wards Air Force Base, in a flight Tesch flew 652.2 miles to a pre For the Silver C, a flight of 50 lasting less than 2Y2 hours announced goal to set a new kilometers distance, a gain in achieved an altitude gain of mark for that record category. altitude, after any low point, 42,303 feet after a low point of Over a period of nine years this of 1000 meters, and a flight of less than 4000 feet, reaching a record had been steadily im 5 hours duration. maximum altitude of 46,267 feet. proved from the 1963 mark of For the Gold C, a flight of H is not likely that these marks 487 miles. 300 kilometers distance, and a will be exceeded by the necessary gain in altitude of 3000 meters. 3 percent unless a pressure suit The Goal and Return Caper A diamond is added to the or pressurized sailplane is used. One of the more exciting ex Gold Badge for the achieve The most glamorous record amples of one-upmanship in the ment of each of the following: category is that of free distance. record-making field has occurred An altitude gain of 5000 In this you are not bound by any over the past five years in the meters, preflight declaration of goals, and category of flight to a pre-de A flight of 300 kilometers can take advantage of whatever clared goal and return to point over either a triangular opportunities are offered. For this of departure. At the opening of course or to a preannounced reason one might expect the rec this story, the record was held goal and return to point of ord to advance by significant by Dick Georgeson of New Zea origin, steps, whereas flights to prean land, who had utilized the lee A flight of 500 kilometers nounced goals might be expected wave from the long mountainous distance. to creep up gradually, as meas spine of South Island. Then, in The progress that has occurred ured by the confidence, or brash the middle of winter, early March over the past decades in the ness, of the pilot. 1968, along the eastern seaboard, United States can be appreciated The first flight over 400 miles where no soaring record had from the following statistics: was made by Dick Johnson in been set for 30 years, Karl Strie Silver C, Serial Number 10 1951, when he flew a startling dieck* of Port Matilda, Pennsyl was issued in 1937, and Num 535 miles over the deserts of vania (near State College), in a ber 100 in 1948. Texas. This flight generated ex low-performance club glider of By August 1968 there were tensive discussion in published steel tube and fabric, launched by 1453 outstanding, and by June articles on the subject of how that a tow from a Jeep driven by his 1973,2458. record could ever be broken. One wife from their own field on top Gold C, Serial Number 10 was proposal which was advanced at of Bald Eagle Mountain, flew to issued in 1947, and Number that time suggested that a flight Mountain Grove, Virginia, and 100 in 1960. could be made in thermals over back in turbulent ridge lift, for By August 1968 there were the California deserts reaching a total distance of 476 miles. 402, and by June 1973, 804. Pikes Peak at the end of the day, One year later Bobby Clifford Diamond Badge (all three then utilizing ridge lift at Pikes raised the mark to 488 miles, fly diamonds) Number 10 was Peak to remain aloft overnight, ing in thermals in South Africa. issued in 1957, and Number 100 resuming the flight to the east A year and a half later Wally in 1968. By June 1973, 253 when thermals developed the fol Scott, a well-known Texas com had been awarded. lowing day. petitor, pushed the record to 534 Johnson's record remained in World Records tact for 12 years. Finally in 1963 • Karl is the son-in-law of Capt. Louis There has been a rather dra it was advanced to 544 miles, Stecher, USN, well-known to many on the matic improvement in equipment and in 1964 to 647 miles. By APL staff.
18 APL Technical Digest miles in the strong thermals of cities before 7 o'clock in the six times a year-and he still had his native state. In November of morning." From the experience two hours of daylight remaining. 1971 Striedieck again took the he learned all kinds of do's and record over the same mountain don't's for this type of activity, This is what 19th century aro ous route generally defined by and sat down to prepare a com naut Louis Mouillard was talking State College, Altoona, Bedford, plete plan for his next attempt, in about when he addressed himself Cumberland, Monterey, Coving cluding obtaining official Weather to those pioneers groping toward ton, and Bluefield. His distance Service support in the person of what was to become Kitty Hawk. was 569 miles. And then the com one of the world's leading soar "I hold that in the flight of the petition began to warm up. Dick ing forecasters, Chuck Lindsay of soaring birds," Mouillard wrote, Georgeson, on a none-too-good Washington. "ascension is produced by the day, flew from Hanmer, New Zea skillful use of the force of the land, to Mossburn and return for Promising conditions again oc wind, and the steering, in any direction, is the result of skillful a distance of 623 miles, having curred on the fifth of May. Bill's maneuvers, so that by a moderate used up almost all the land dis flight plan called for take-off at 6: 00 a.m. and a flight of 11 hours wind a man can, with an air tance available to him on his and 50 minutes at an average plane, unprovided with any mo Pacific island. Exactly one month speed of 70 miles an hour, for a tor, rise up into the air and direct later, on 7 October 1972, Strie himself at will, even against the distance of 816 miles along the dieck scored again with a 637 wind itself." slightly curving mountain ridges, mile flight from his Eagle Field Mouillard would have been and a straight-line distance, which to North Tazewell, Virginia, and dazzled by the modern sport of is the record measure, of 783 back. On 9 October, only two soaring. For it represents the ulti miles-just 100 miles more than days later, Jim Smiley, an airline mate distillation of what he had Karl's record of the previous in mind, a sport that combines pilot living in Clover, Virginia, October. The turn-point, the goal, incredible beauty with the sort after telephoning Karl to find out was the intersection of V.S. Route of excitement that seizes a man's what he had to beat, flew from enthusiasm to the extent he tends Bluefield, West Virginia, north 19 and Alternate V .S. 58 at Han sonville, Virginia. to become a bore about it. Soar to Lock Haven, Pennsylvania, and ing is an all-encompassing sport, back for a distance of 657 miles. Take-off was two minutes later and one who suffers an addiction Eight days later, on 15 October, than the planned 6:00. The turn to it need take no more than one Striedieck declared a goal of point was reached at 12:07 p.m., flight to realize he's become in Rosedale, Virginia, and made it four minutes behind the flight credibly and helplessly entwined for 683 miles. On this flight he plan. Landing back at Lock in this romance of the sky. flew in company with Bill Hol Haven was at 6:03 p.m., still Reprinted with permission from the July brook, corporate pilot for Kelly four minutes behind schedule, and 1973 issue of Relax magazine. Springfield in Cumberland, Mary there were still two hours of day land, who, in many years of light remaining! soaring, had never earned his Dia It is hard to predict what ac mond for distance. V nder Karl's complishments man will wrest tutelage he managed to eke out from Nature in the soaring arena 657 miles, landing in Altoona, in the years to come. While sail while Karl continued on to Eagle plane design appears to have at Field. tained the ultimate, it probably In February 1973 Bill made his has not. While man's knowledge own assault on the record, using of the atmosphere and ability to Lock Haven as his starting point. extract the most from it seems to The attempt ended in ice and have reached the peak of per snow at Altoona one hour later fection, it probably has not. Con in what Bill termed "the fastest ditions such as made Bill Hol Author in cockpit of a typical high-per glider flight ever between two brook's flight possible occur about formance standard class ship.
Volume 12, Number 3 19