Low & Slow Issue 2 1971 by US Hang Gliding & Paragliding Association

LOW & SLOW 2.1

2.2 Photographic policy of Low & Slow: Preference order: 1. Send in a black and white negative and I will return to you a positive print as I automatically return your negative(unless you tell me to keep the negative for the l&S archives). 2, Send in a velox at ·85 line screen preferably. 65 to 133 line positives are acc•ptable. Newspaper clippings are accer,table. J. Send in a black and white photograph not larger than 4' x 5" and preferably in the smaller range of sizes. Larger photographs are acc•ptable. 4. Send in color transparencies or prints. NOTE:Negative1 will always be returned at my expense.Other items will ~~ be returned if the sender contributes a self-addressed stamped return envelope. AdYertiser 1 s photographic policy for l&S: The cost of screening will be carried by the advertiser. Send in any kind of material~but your lowest coat method will be by following the priorities listea above. The charge for printing area of your photographic materials is S2 per square inch. If you send in a velox there will be no further charge. *************************ADDRESS FOR ALL CORRESPONDENCE TO LOW&SLOW: 59 Dudley Ave. $6/12 issues NOTICE!! ! ! ! ! ! I ! ! Venice, CA 90291 Cover photo by Gail Osherenko. File No. 71-03320 File No. 71-03321 Subject: Joe Faust Age 6 with CERTIFICATE OF BUSINESS, father and a sled type hangFICTITIOUS NAME glider: Area of flat pattern: The undersigned does certify he is conducting a business at 59 Dud75 sq.ft.; Leading edge not in~ ley. Avenue, Venice 9029-1, Califoreluding side panels is 5 feet; nia, under the fictitious firm name chord of wing is 10 feet; thus of LOW & SLOW (or) K.I.T.E. aspect ratio is 5/10 = 0.5;the SOCIETY OF AMERICA and that said firm Is composed of the foleffective wing loading was 1.0 lowing person, .whose name In full lb/ 1.0 sq.ft. Gross wt.:50 lb. and place ot residence is as fol~ Ship material coat: $3.00. Ship lows: · Joseph Patrick Faust, 59 Dud·!!!ake hour cost: 1 hr.or less; ley Avenue, Venice California Ship wt.:~ 4 lbs. Material cost 90291 •. is paying high retail prices & Dated February 24, 1971. could drop to about S1.00 if JOSEPH PTRICK FAUST. qne bought well for many ships. STATE OF CALIFORNIA,

UP.!sf2~~,,r up&down

~ by Joe Faust, 1971

LOS ANGELES COUNTY: On February 24, 1971, before me, a Notary Public in and for said State,· personally appeared Joseph Patrick Faust known to me to be the person whose name Is subscribed to the within· instrument an(i acknowledged he executed the same. (SEAL) LEONA BAYNE. Notary Public, Pub. March HI-18-25-1971.

Photos by George Uveges of Miller's early Rogallo

.·

The First Leap

2.3

Richard Miller --i:-ere are few sports that offer so great a variety of challenge as the design, construction and flying of a hang-glider, and none that brings us so close to man's age-old desire to fly like the birds. Its challenges and its charm assure that when ita day comes, and that day now seems close at hand, the popularity of the hang-glider will be great. In the meantime, there are many mistakes to be made and much to be learned. A lot has bean learned already, of course, and it .would be easy to fill a number of issues of Low&Slow with experience, observation, caution, exhortation and historical example. What seems needed immediately, however, is a brief outline which will provide a few rough-and-ready rules for the designer. What follows is intended to fill that need, but can only hope to do so in a limited manner. In time we shall have much better, but until that time we offer the following: FIRST CHOICE: There is a greater variety of types available to the hang-glider builder than might at first be supposed. A number of these are considered below, in roughly ascending order of performance and with an approximate L/D figure appended to each. The L/D figure - our first leap into the void - is the best estimate we feel able to give at present, and should by no means be taken too seriously. *ROGALLO WING (4) This type is ideally suited as a hang-glider in · many respects. It is easy and inexpensive to build and can be transported and assembled with ease. Making it turn is the problem. Being essentially a flat plate, it will need about twice the area of a ship with an airfoil to do as well. It is loads of fun and a good step up. *PLATZ SAILWING (5) So far as we know, Platz (Fokker's great designer) is the only one to have built and tested this type.Its not strictly a hang-glider as envisaged by Platz, but adaptable to the purpose and certainly worth further investigation. *LILIENTHAL MONOPLANE (6) This is probably one of the least desirable types for contemporary use owing to its complexity (umpteen wires) and low efficiency. It would be a shame if no more were ever built, however. *TANDEM MONOPLANE (7-8) This has much to offer as regards construction, control system and stable position for the pilot. Strut bracing and dihedral (just a bit) would probably be preferable to Montgomery's adaptation. These are probably a lot of fun, _especially on a balloon launch!

2.4

Lilienthal

*CHANUTE BIPLANE (8-9) This is one of the world's perfect airplanes and a justly perennial favorite. It probably offers the lowest airframe weight/area of all types reviewed here. The biggest problem is assembly, but some sort of slip-in-socket wing strut or overcenter wire tightener might solve that problem, as might the use of struts in place of wires.

*MONOPLANE TYPES (10-15) Neither the low nor mid-wing monoplane seems to stand the best chance of becoming-fue standard configuration. Most everything falls in the right place;it is wide open for development. *FLYING WING (10-15)-swept type, not plank. This has advantages of simplicity, low airframe weight, plus low drag. A solution to the problem of lateral control may be more complicated than with other types. The sailwing version, of which I've built a prototype, appears to offer the greatest performance return on work/money investment. It needs thoughtful development •••••••••••••• a dark horse. (See bottom photo of p.2.10) WING CONSTRUCTION: Just as there are a variety of aircraft types to choose from, so there are several variations in wing styles. These fall into two main divisions,the sailwing and the built-up wing of either single or double surface. When the trailing edge of the sailwing is left untether~ ed, as is generally the case with the Rogallo, a flat plate of relatively efficiency results. A sail suspended between proper leading and trailing edges and giving a proper airfoil,on the other hand, has been shown to provide as much lift as a conventional built-up ·wing. and for far less work and trouble. THE problem with sailwings is luffing, and it is quite dangerous. Ribs onto which the sail can fall, or battens, appear to be the best solutions. The simplest suitable built-up wing consists of two spars with formed ribs and a top covering. A single-surface wing of much higher efficiency might be possible by using a layer of glass with honeycomb reinforcement. The ·double-surface wing can either be built using fore

iow

2.6 and aft spars and fabric covering -a la primary glider- or with a D-tube. The D-tube type would seem to offer the best solution for a Some day we'll have wing of light weight and long span at present. filament reinforced fiberglass wings with large cantile~er spans, but don't hold your breath. SIZE AND WING LOADING: The primary factor governing all considerations of size, weight and wing loading of the hang-glider is the necessity to take off and land running. This is further qualified by the range of wind speeds in which it is pleasant and safe to fly such light machines. We might assume that practical running speeds are on the order of 10 to 15 mph (a mile run in four minutes gives an average of 15 mph and a 100 yd. dash in 10 seconds a bit over 20 mph) and practical wind speeds for flying between 5 and 20 mph. If we join these two sets of figures, and use the basic equation of lift to express wing loading in terms of airspeed, then we arrive at wing loadings which tally closely both with the historical types on which we have data and with our own experience in a variety of machines: Taking three sample points for w Weight of loaded ship deriving wing loading from a form of the basic equation of lift: s Wing area ! : ( cL R ) v2 V Airspeed s 2 Half the standard sea VI R Flying speed, V Wing Load, "S" 2 level air density lbs/ft2 mi/hr (or) ft/sec C1 Coefficient of lift of our wing (Here assume to 20 1.0 29 be 1.0) 24 1.5 35 28 41 2.0 Whereas at first glance the lighter loading seems the most attractive, there are some contrasting considerations to be taken into account. To illustrate these, let us put down some rough specificationa for two ships,one with a loading of 10 lbs./sq.ft,, the other twice that. We will assume a pilot weight of 150 lbs, and a standard airframe weight of 1/J lb./sq.ft. of area. Wing Pilot Airframe Gross .Area Loading 150 lba. 75 lbs. 225 lbs. 225 ft~ 5ft.x 45ft. 1.0 lb/rt 2 Jft.x 30ft. 2.0 lb/ft 2 150 lba. JO lba. 180 lbs. 90 ft~ From this comparison we can see that the larger glider is going to be about 2.5 times heavier (75 lbs./JO .lbs.) (and presumably more expensive) than the smaller one. It is going to require greater space to build and to store;it's probably going to require a trailer rather than a car-top rack for transport. It will be difficult, and perhaps even dangerous to handle in all but the lightest winds. Against this, of courae,we have the higher take-off and landing speeds of the heavier machine. What we aim at then, is to strike a balance between one set of requirements,centered mostly around the aerial performance we desire, (Please find First Leap continued on page 2,15

2.7

A HANG-UP ON HANGLIDERS By

George Congdon (With Mr. Congdon's permission we have reprinted this article. It was also printed in West Wind. January,1971.) At the risk of being classified as some kind of a nut,the following account of past experiences and problems involving hang-gliders is offered hoping that you will still think of me as a common everyday run of the mill glider guider. This whole thing started back in primeval time when I was a hawk watcher with an eager desire to get off the ground; this was about 1932. Most of the gliding activities were in the eastern part of the U.S.A. and in Germany. However, on rare occasions Popular Mechanics magazine would publish plans for an aircraft commonly known as a hang glider,e Tn idea of building a hang-glider appealed to me greatly; first of all it was cheap,easy to build and there was no FAA that would say that I couldn't. I was living in San Jose at the time my brother and I decided to build one. We had the idea that we knew how a hang.glider should be designed; we therefore altered the plans to suit us. We purchased spruce, wire and some cheap muslin to cover the wings. It was put together with stove bolts; and when it came time to dope the fabric we used a heavy mixture of starch and water to seal the cloth. Came the day to try it out---this had to be the greatest gliding moment of my life. It was important that we picked a windy day as we were not exceptionally fast runners. The glider was assembled at home and a small wagon type trailer was made so the glider could be towed down the road sideways behind The site we had chosen for the launch was about three two bicycles. miles away in the foot hills of San Jose now covered with tract homes. It was a gentle grassy slope about one hundred feet high. We excitedly hauled the machine about half way up, not wishing to The ship was a biplane with a hole take too many chances right off. in the bottom of the wing for the pilot and a leather strap to straddle to help carry the weight. I got in position and ·started down the hill, first running slowly to get the feel of it. The first sensation was that I found myself running on my toes as the machine gained lift. I didn't get off the ground this time, but was highly inspired with the fact that the thing really wanted to fly. The next try was more like an extended broad jump at about the same location. Finally,! decided to go to the top of the hill where the wind was stronger. After much perspiration getting it up there I was ready for the big leap. I started down the hill running as fast as I could. This time I kept a little negative incidence in order to get traction. At the moment I thought I had enough speed I threw my weight to the rear and WOW, I

2.8 was in the air at about three feet off the ground. I sailed along twisting and turning to keep the machine in a flying attitude. I must have flown over 50 feet. I really f~lt like a bird this time. !was so excited that I could hardly talk. It may have been because I was out of breath. My brother was the next one to try, with about the same results as I had. We didn't know it but we had a dragon by the tail and could have gotten hurt if we had gotten too high on these flights. In fact, we ended up with numerous skinned knees on days when the wind wasn't strong enough and we were· speeding down the hill faster than we could run and not really getting off the ground. Our misstake was that the machine was too small. We built two of the ships. My brother's ship eventually became a triplane in order to get the needed lifting surfaces. Hie glider also flew; our flight became longer and higher~-at the most about ,ten feet in the air. We didn't feel we wanted to risk a higher hill, the experiences were scary enough as it was. There are probably many persons who have tried this thing in the past and who have never mentioned it. I know Les Arnold has done it, in fact, I eav an old picture of his hang-glider. It was similar to mine but he used a rope on each wing tip and two persons to pull him into the air. His activities were in Hayward. Jack Lambie 1 s article in Soaring is probably the reason that I decided to write on the subject. His glider had a 28 foot span and mine was only 22 feet, but I had a wider wing chord than his. In the 1930s there was an actual manufacturer of a hang-glider somewhere in the east. It was an unusual one in that it was very thIt was a biplane with fabric covering on both ought!ully designed. sides of the wing. The bracing was done entirely with struts for easy assembly. I remember seeing an old brochure with pictures of two or three gliders with people in them standing on a hill top ready for take-off.I never saw any actually in flight but they certainly looked like they would fly. I still have an old clipping of that glider. With present day knowledge and technique it is possible to build a reasonably good machine, one with a little more control. I found it important to have some aileron action as it was difficult to get a wing down in case of a gust. This too would help from drifting back into the hill and prevent a possible disaster. Although the L/D is next to nothing, a strong wind up a slope could promote a couple of passes and an actual soaring experience. The real danger in these things is a headstrong pilot who wants to leap off a mountain and into headlines. Actually they are not dangerous providing one use discretion.Height and dietance is regulated by the size of the launch site. The experience can be anything from an extended broadjump to a flight of a hundred feet or more. As Lambie said in his article----it is real fun and has the possibility of becoming a popular thing. It does,however,take an agile person to do it. ******************************************

7.9

Area Men Revive

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EarIy A!.!,!!.f2..

By TODD CROWELL ._<.§ SAN CLEMENTE - Someo_ne happening to pass by the Harbor Hills 8 Golf Course on a Saturday afternoon _2I might be treated to a sight straight out of ~ the early history of avi~tion._ 5 If he came at the nght time he would see an individual lift up a wmg-hke c contraption on his shoulders, take a short r;;15 · run down the hill, and then_ glide gently through the air for a f_ew bnef moments before settling back down into the !urf. ;:: For the slopes of the Harbor HIils golf ~ course are like the dunes of Kitty Hawk .,.;- for a small group of glider enthusiasts ~ who are trying to revive interest in ~ primitive gliders. :; Dick Miller, a resident of San Clemente ::,:: and a contributor to various sports

i ~:~e~:: tr:tg:::;~li~n;~:s ~:~~~~~ ~own, is a ~port whose time has c~me.

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1t seems a little strange and esotenc now, ~ he says, think what surfing must have P.. looked like several ~ecades ago. . . § For years the ma~nstay of sports gl!ding rn has been the sailplane a highly .-. streamlined aircraft built along the lines -;;; of a conventional aiq>lane. Sail planes ':, are towed to high altitudes by powered :!; aircraft and then released. They often a stay in the air for hours lifted along by rising currents of air. ......... But the costs of sailplane flying are beginning to get beyond the reach of a, average flying enthusiasts. A modem 0 ""~ high performance sailplane now costs as 0 "' much as $12,000 not to mention the • -g incidental costs of towing which is much E-o .... more than most people can pay - hence 0 the renewed interest in a cheaper, § simpler era of flight. -;;: The first heavier-than-air flights in ~ history were made by the German f;; aeronaught Otto Lilienthal in a glider not °' very different from the hang gliders of Ji' today. His early experiments (one· of +> which caused his death in 1895) and the -~ simiiar efforts of other pioneers in ·flight

0. CD

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~lli,Wright Brothers in 1903 . After the success of the first powered flight, interest in gliders quickly waned - but not completely. Over the years, .amateur aviation enthusiasts would read about the efforts of the early pioneers and try to build their own copies of the primitive gliders. Very often they failed because they lacked knowledge and a common body of experience to build on. Miller is trying to correct this. He is helping to promote a hang-glider tournament in Capistrano Beach this year. Tentatively scheduled for May 23 the 123rd anniversary of the birth of Otto Lllienthal - it would be the first meeting of its kind in the country. · Miller hopes that IO or more hang glider enthusiasts_ will show up for the two day ~~f~:~;~i~~:.::~:~~e::~%!:: ~u;;hs::e;:~ longest distance covered and the longest duration of flight. · The main purpose of the meet is to provide a chance for glider builders to get together, exchange ideas, and build on eachother'sexperience .

Several years ago, enthusiasts started a newsletter called "Low, slow, and out of Control" for the same purpose. The original letter is now defunct but only last month a new newsletter was started up again to spread the word about gliders. Miller claims that with work and a lot more experience and experimenting the nang-gliders could be made to soar (stay aloft using thermal updrafts to keep 0 airborne). That, of course, would be the N ultimate thrill of the sport. It all goes back to a primitive urge of , man to fly like a bird. Hang gliding could <=I _be the closest approximation of bird flight 0 that a human could attain, he said. Not .!; even sailplanes with their boxed-in ,.g pressurized cockpits gives one the same °' feeling as a short flight in a primitive :l:

•.

glider.

In a sense, it is a new frontier, he says - one of the few left today.

2.11

2.10

FREE AS A BIRD - As Dick Miller watches from tile crest of a bill, Bruce Carmichael tries bis wings witla one of Miller's band built, aluminum frame

bang-gliders on the slopes of the Harbor HlUs Golf Coane. 'lbe kite-like cont111ction is a Rogallo type bang glider one of several ~fferent ldHI el gliders

up&d0Wn

up&down up&down up&down up&down

that cu give a man a lt8 foot ride - if the wind is right. .

JSu-PoltPMlol _ Bird insert photo by Uvege1

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Photo--at -far left bottom,2. see- 2·.'5- ,,;Flying Wing" in Miller's "First Leap". Tbat is Miller off the ground near his home,rather ·in hie own backyard heading for a cliff that drops almost straight down to the San Clemente waters. The low and slow ship promises to be one of the best te kiss the sky. Its. dive rate and angle attack criticality are topics I am anxious to hear about. Let us not rush this ship, though, for its potential is worth the pains of waiting. (P.S. Miller had no intention of going off the cliff. He controlled to stall and landed a good distance from the drop,)

2. 12 From Dr. Bruce Carmichael: Richard and I have been slope soaring balsa models each Sunday morning at the site of your first Rogallo skims. I have the aluminum extrusions and 1/32" finish birch aircraft plywood for my hang-glider but still have not got the sheet aluminum. With Richard's prodding and help we got a sample rib built.It is nice and sturdy and weighed 2 oz •••• it will take a lot of help to get the ~hip done in time for Lilienthal's birthday. We still have hopes. It ~ill be soarable in any decent slope wind -I feel confident. The span fa 32' ; chord is 50 11 ; airfoil: 63. (10)-12; leading edge is covered with plywood; wing covered with 1 mil Tedlar(1.0 lb. covers 139 ft~); £uselage: triangular truss; swing seat;and controls to spoilers which will give lateral directional control used separately and glide path control used together; weight estimate: 40 to 45 lbs.; material cost estimate: 200 bucks.Let's hope others come up with cheaper solutions! Ed.: Bruce, we urge you on. But I do .II.Qi think we will get to see you much on the 23rd. My figures give you a merit number of 0.15 which,according to your chart as referred to in Miller' s"First Leap~'is in the supersoarable range. We hope that you are keeping a problem log,cost log, and photo-account of your experience with the new bird.These will be key to the development of lower cost systems. From Bruce again: "This walking on air is exhileratingl" *********** *Attention: Bruce has a must reading article in l.&S 3 to - go along with Miller I s "First Leap"

NASA TN D-629 NaUonal AeronauUcs and Space Administration. AN EXPLORATORY STUDY OF A PARAWING AS A HIGH-LIFT DEVICE FOR AIRCRAFT. Rodger L. !~eseth. November 1960. 31p. OTS price, $1.00. \NASA TECB'NICAL NOTE D-629)

I. Naeseth, Rodger L. Il. NASA TN D-629

(Initial NASA distribution: 1, Aerodynamics, aircraft; 3, Aircraft.)

] wind-tunnel investigation wu made of the high-lift ~apabilities of two supersonic airplane configurations equipped with parawings, which are lightweight, ~towable, fabric wings of parachute-like construction that may be used for take-off and landing. The use of a parawing which had an area twice the wing area of the airplane model to which it was attached (canard tlomber model) resulted in a threefold increase in lift cbefficient at an airplane attitude of 120. The static lateral stability characteristics of the canard airplane model were improved by adding the parawing. This card our 1..&S G was contributed by eorge Uveges. Coples obtainable from NASA, Washington

NASA

2.13 From Patrick Page: 1. Patrick has been supplying the tid-bits o~ a Rogallo series of fl~ that are taking place on Mission Peak, CA. See I..&S J. 2. "The hang-glider,to be appealing to the over thirty type pilot has to be soarable. I feel that this is the main deterrent to its growth among the nnt so athletic types. Full control at all times is the next most important item;afterall,the older set has by th~t time learned the value of life and health.Fighter pilots thus hafe to be the younger set. As you know, there are bold pilots and alfo there are old pilots, but there are no old and bold pilots!! Ed: Thank you, Patrick. For sure, the I..&S gamut of activities covers control and soarability!Some of our goals cannot be with- 1 out soarability, but others must not be so. At least one of our fellow birdmen is dwelling for a while on my suggestion of the sport of Running:--Jumping-Gliding where the object of the type is not unlike the ostrich run. Such is definitely non-soaring but is up-lifting. Such flight can be part of a program of rejuvenating our body -a birdman's jog program, perhaps. Patrick, we have definite sights on one-man low-cost soaring ships that will have full controls. There ARE old and bold pilots, please permit, but I do not recommend that anyone do more than is really good for himself. On this point let me give support by a quick book review: Book Review: Jonathan Livingston Seagull by Richard Bach: This story of a seagull parallels the I..&S movement: Flying is life: wisdom places one on a path of knowledge-seeking that ends in the ultimate expression of flight:being everywhere and in all times for the purpose of sharing the good of life with others. The boldness of the elders brings life to the younger gulls. I'

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Page gives us this bit of enjoyment: He heared that Perry Whincup of England tried to win $12 worth of groceries-a-week-for-life by flying his homemade canvas wings from the roof of a local supermarket a~d across the River Nene. We do not know whether he did or not win? The San Jose Mercury titled the report "Kan Cannot Fly on Groceries Alone!! I suggest that someone try to contact Perry Whincup in Peterborough, England, or thereabouts. If Perry fell in, maybe he can be reached, ************** downriver. An Equation of LIFE: L • K C1 S V 2

Ed.

Dear Editor: Many thanks for Low&Slow, I enclose copy of a shot of a ski-equipped Hang Loose for edification and possible market(every skier at Aspen) for Lambie whom I have never met but looms large in my mental filelof favorite kooks. One Hang Loose under construction in Independence Mo,, basement, no Rogallos, sorry about that Kr. Miller.I like therlow a~a slo~ life style out it dio not really do a whole lot for brothjrs . Lilienthal. Pilcher and Montgomery except in a sort of a permanent way. Signed: Thanks. Arnold B. Crank, Picture editor and Doc Savage fan. Ed.note: Pilot hang-glider flight waR 150 yds. at Powder Ridge ski: area near Kimball, Minn. on 3/22/71. Ship cost:125:Pine and bamboo strips. Pilot: Ron Greeley~ Associated press photo. I..&S photo use cos_t: .Sc?5! I I

Photo only by George Uveges

BIRDMAN'S DRE.AM Through the ages since time unknown In legend and myth man has flown On carpets and chariots and even a horse Of a sleigh and reindeer - you've heard of course Icarus and Daedalus were first to try it The great wish: To build a machine and fly it Leonardo discussed the birds as tho' they swim As water is to fieh, so air is to them Nowhere in all nature is a shaft revolving Yet witr. time eternal, a wonderoue evolving Hae inhabited the earth and the sky With insects, and multitudes of birds that fly A step a jump and a flapping of wings Born on a breeze above all things As a bird from the nest- The conquest of flight it laet man is free of his earthly plight Feel of his freedom--Know of hie worth Break the tradition that binds man to earth Sail in the sky as a bird on a lark To ride on a breeze o'er folks in the park What a thrill 'twould be to fly as a bird To catch on a wave. and soar with a cloud To survey the earth below, as an eagle hie prey A sweep of the landecape--Then on your way Alight and gaze, from a dizzying perch The glorious panorama of nature to search To soar on a lift, ae thermals blow Then drift to the crest of the earth below 'Twas man such as we who dared to conceive Wonderoue things you wouldn't believe The movies the cars, and joys untold Of luxury before your eyes unfold With a thought to contrive, a heart to perceive Let us prove to all -what we believeTo build a machine and conquer flight The time is now, the place is right Flight in space. but a wish in the past With patience and diligence, has come to pasa No impossible dream the urge to fly A proper machine will soar in the sky To ski or sail, or to ride on a horse Such sports are for the agile of course To fly o'er the rainbow at will Will surely be man's greatest thrill From cupid with arrows to witches and brooms Do their work on earth ••• Then gone with a zoom No-w that I have had my say Let's be on with it-~Up and away Herb Aldridge

(continued from 2.6: First Leap) 2.15 and an opposing set including most of the non-flying requirements. On the basis of the experience available to date, and assuming that the gliders are designed and constructed with some care, we would recommend a figure of about 1 .5 lbs./sq.ft. as a starting point. (0 u r 150 lb. man would now have a 42 to 43 lb. glider with a wing area of some 127 to 128 sq. ft. giving a 4 ft.x 32 ft. planform.) Gliding kites such a11 the Rogallo will do better at about half this figu~e, that is, 0.75 lbs./sq.ft., while the more carefully designed ships will be able to edge above 1.5 lbs./sq.ft. In time, as ships increase in efficiency and pilots in ability, the figure of 1.5 lbs./sq.ft.,or even 2 lbs./sq.ft., may come to seem I quite tame. For the time being, however, these modest weights wlll probably be all we can handle. I· SINKING SPEED .AND SOARABILITY: I The ability of a glider to soar is dependent, above all else• ion its rate of sink and this sink rate can be judged roughly by a me~it number equal to the weight divided by the square of the span. A chart :based on this calculation (among others) appeared in Vol.1, No. 3 lof ·"Low, Slow and Out of Control". It was prepared by Bruce Carmich9-el who divided the chart into areas applicable to ships rated las I "Klunker", "Marginal", "Soarable", and 11 Super(soarable)". In the ~r. Carmichael chart, "Marginal" ends and 11 Soarable 11 begins at 0.35 ind extends down to 0.19 (the lower number having the higher merit) lat which point the "Super{soarable)" range begins. Some representative figures, all which fall within the "Soaral:ile'' range, are given below: Merit number taken Ship Weight/Span squared non-dimensionally Schweizer 1-26 560/. 40x40 0.35 Schweizer 1-23 640/ 44x44 o.J4 Skylark I 665/ 45x45 0.32 BG-12 750/ 5ox50 0.30 Morelli M-100 577/ 46x46 0.28 Libelle 666/ 49x49 0.26 AS-W-12 912/ 6ox60 0.25 These figures can readily be bettered,and by appreciable margins, with the light-weight gliders.The hypothetical 1.5 lbs/sq.ft. machine (192.lbs./.32 ft.-span x 32 ft.span) mentioned earlier, ,for example, gives a merit figure of 0.19 -right on ihe borderline between"Soarable" and "Super(soarable)". Thus we can immediately see that there is little cause to have doubts about the potential soarability of hang-gliders. Nonetheless, some qualifications and warnings are. in order as follows: 1. So long as the hang-glider pilot produces just about all +e drag by virtue of his presenting the maximum area of his bo dy to the airstream, figures of merit like 0.19 must be treatied with a bit of skepticism. 2. Long wings, for all the pleasant things they do to our sinkspeed, require greater skill to design and to build, and ul"fii.1

2.16 mately present ground-handling and flight problems such as, J. The VERY CRITICAL one of the safe minimum speed of the inner wing-tip of a slow flying glider in a tight turn.Consultation with the handy turn-radius nomograph of Ha1ckinen indicates that a lightly loaded glider with a span of 40 ft. will be able to turn within a 60 ft. radius. To the extent that such tight turns permit staying close to the hill while slope soar>ing, they are greatly to be desired; but to the extent that they result in a differential of 2 to 1 or more in wing-tip speeds and the possibility of a snap-roll at very low altitudes, they are to be approached with the greatest possible caution and withthe most careful attention to wing-tip design and the effectiveness of the lateral control mechanism. From the foregoing considerations we can begin to see the main outlines of hang-glider design emerge. The most critical dimension, wing span, will probably need to be at least 26 to 28 feet, even with a light machine,if we hope to achieve a good rate of sink,and perhaps w~ll not want to go much higher than 34 to 36 feet until we are more c~rtain of our solutions to the turning problem. This will result in a'spect ratios on the order of six or seven. I I Other aspects of our design will be governed by the type of glider w,e have chosen to build, but stabil.ity requirements will be pretty much I 1h11 same in all cases.Because response to fore-and-aft balance changes tind to be quick and precise,and that to lateral changes on the slug©ish side, we will want good stability in pitch (adequate horizontal t~il surface and generous decalage)and marginal directional stability (little dihedral and not too much rudder). The choice of a good airfoil is always a problem, and will probably always be one, but for a start one might consider the low-drag sections of the NACA 44 and 63 s1eries. : A11 for building materials,there doesn't seem to be much to choose ietween wood or metal in a glider weighing 45 to 60 lbs., so one will Jrobably do well working with the material he knows best.But what oportunities for new construction techniques employing paper, honeyomb and fiberglass II The use of filament-reinforced fiberglass is articularly attractive in light of the very small quantities of such materials that will be required in these ultra-light-weight.airframes.

PROOF LOADING: The hang-glider is essentially a one-speed machine, and that speed is slow. r.onRequently,it need not be stressed for those ranges, say two to three times cruise speed, at which high proof-loading figures quickly degenerate.It will take a lot more experience than we've had to date to establish a safe and reasonable figure, but it's hard to imagine the need for a proof-load that is over 2.5 to 3.0 times the working load. In the meantime, try sand bags and common sense.

2.17 WING BRACING: The biggest aid in making a structure both light and strong will be wing bracing. In round figures, a braced wing need be only about half the weight of an unbraced one. The small drag lossea at very low airspeeds make this an excellent trade-off.Wires can probably do more for the amount of weight and drag involved,but can be a bother to rig. L,si_ngle strut, or a pair in the case of a two-apar wing, seems ~he best compromise.

CONTROL: No one who has felt the delicate response of a hang-glider to the slightest fore-and-aft movement of the feet -that's flying, aanl-.is going to consider the addition of an elevator as anything but superfluous. Lateral control, which of course is necessary for sustai~ed soaring, is another matter entirely. On ships with somewhat longish spans,the sideways movement of the lower body is not going to be adequate to assure turning with precision. It might be possible,however, to devise a system of rails or slides which would permit shifting the pilot's entire weight from side to side to a sufficient e:d.ent to obtain the required control. The alternative is some system of wing-warping, or the use of lateral-control devices such as spoilers or ailerons. While this sounds simple, it ain'tl There are wires, hinges, pulleys and turnbuckles, of course, but a bigger problem is freeing the hands sufficiently to permit precise manipulations of the control handles. One should also be cautious about any kind of handles, hinges, bolts or fittings and the like in the area of the head or forward of the b~dy which might be encountered as one flys forward out of the ship -&nd I someone will! Remember Montgomery! There is no problem which will require greater imagination and ingenuity to solve than that of lateral control.

SEVEN SAMPLE "What to do's: 11 1. What to do when you get tired of hanging by your armpits (and it doesn't take long!): S 1 id e into a .small swing seat suspended just where it should be by four lines;but watch that C.G. shift! 2. What to do if you get tired of being dumped face first onto the ground when you misjudge landings, or if you're afraid of falling out of the bars while soaring at 83 feet: Figure out a way to strap yourself in, but also figure out what's going to happen when you trip during a hot landing and the machine runs_over you. , 3. What to do when you've had a good flight and are coming in too high: If you have individually operated spoilers or aileroJs, use them in unison. If you have a drogue chute, deploy i~. Try harder ne~t time.

2.18 4. What to do if your sink rate is good, but· not good enough: Experiment with partial body shields and in-flight changes of position -prone, supine, squat, frog, hunch- to reduce drag. 5. What to do when you find need for a bit more wing loading on a windy day: Install water ballast, of course. 6. What to do when you get lonely up there all by yourself:Build the world's first two-place hang-glider. 7. What to do when you've solved all those problems:Don't worry! Another one will be along in less than a minut~. The end. Thank you, Richard Miller, for your contribution.

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HR1116- i NGAll .Low & Slow readers: We need your subscription and your friend's subscription. $6 per 12 issues or trial at L&S 2 together!!!

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· 2 19 "DYNAMIC SOARING" continued from L&S 1 • 7 by Richard Miller: • Klemperer's third glider, the Aachen "Ente" of 1922, was built specifically to experiment with gust flying. It was a canard type, that ie, with the horizontal tail forward of the wing. Thie configuration was adopted in the hope that frontal gusts ,acting on the forward surface and momentarily increasing the angle of attack of the wing, would tend automatically to utilize variations in the relative wind. The tail-first design was considerably lase satisfact_or~ in practice than in theory, however,and moreover,suffered from lqngitµdinal instability. Klemperer's canard configuration was only one of a number of methods used to try to trap the elusive guet gradient. The method Fhich seemed to have the most in its favor, and the one most commo~ly employed,was to mount the wing so that it pivoted about ite longithdinal axis on a line near the center of preeeure. · The Darmetrdt "Geheimrat", also of 1922, featured such a system. In flight,the jlevator of the "Geheimrat" wae to be left locked in position and fhe longitudinal control, as well as response to favorable gusts, managed by manipulation of the wing. Only in the event of the pilot find~ng himself in an attitude from which he could not recover by use of the willl; "-lone would the elevator be brought into play. i I The wing-controlled gliders, although probably superior to other variants, presented structural problems that were not easily maste1ed. I The forward tail of the "Ente" was one way around the problem.Another was the aileron linkage used on' monoplane glider designed by Finsterwalder and Von Lossl and built by the Bavarian Aero Club in 1921. 'In this ship,changes in the angle of attack of the wing were effected by rotating both ailerons in the same direction, while lateral contfol was maintained in the usual manner, by aileron rotation in opposite directions. (TO BE continued in L&S J) *********************************************************************

PAPER GLIDER by George Uveges: The following paper glider was given to your editor for testing. My average "L/D for the ship was 4.2. To inake: Use 8!" x 11" paper of 16 or 20 sub-bond. Let the 11" be the spanwise direction. Fold a 5/8" elevator along the back edge. For the airfoil leading structure begin with a first fold that is 9/16 11 and then keep folding over until 6 bends have been made with the l~st making a 3/4" wide camber. The distance from the leading edge to the trailing edge should be J!". Then fold longitudinal folds as shown: ~ ,

"FLYING WING"

TJ/4"

+- 5/e" !

·I

Adjust the side vertical stabilizers for circling flight. Modific~tions include taping closed the fuselage, cutting ailerons, slitting ha~ing fuselage. £:or. a rudd_er, attaching a C.G. adjusting paper clip, or g1·ving a neat paint Job to it. Thank you, George!!!!

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Phis space can be yours for $12·, Readers will look forward to ·seeing your ad in this E1pacial place. You will have five close lines ir 3 double spaced lines or whatever. You may mix photos and drawings, Have drawings in black lines on white faper. Send 85 line relox or negttiyel See P, 12. Low &.Slow riaders will te on thB,iQokout for t~·me and materi~i costtaavingst hey will watch for ,stemswell of m~ ou eriawill s that save.weight an et , T8evf novel ani eas. heyfw~n low & lo but nave wio 1ortunit to sel our main oo ain s to reliabi a eo it e rou o 1tle.good e1r ctes1res ho e ul or h e ofru &S Ad rates:One space is define But at full 1 columnJwhich is ov JOE HAS A KITE FOR YOU FOR. want to hear from someone as the area one character uses er 8 Bau~., incqes,. he ch~rge! use as a gust detector when We ne line is equal to 32 spaces will bQ ~1 , Thie wi 1 hold y ~bo~t the performa~ca charactern 'f marks are n t placed in for one ~o umn, ~ 1, and fu you are gliding down slopes: istics of the machine shown in .Yi of the spaces. 8ne column is page gricee.run.,~~ a~ or MGM 1 s Brewster McCloud . vertical st~ck of 51 close lin 18er:aP{0 f{t~! 8 • 1, j~, 148, Good weather for l.&S flights: s 3 lines will be sold as one ~epends •••• Tornado to dry night ect1on. 15 sections stacked mak Subscribers paid up for one year in Death Valley air. Send ideas. one column 24,1971: · ~nimum order u~1ng 1s j ±~parators, 1nes for, 1 or more as of March We need go~d pho~os & pog; ?nee 'rders are taken on y in mult1f 1 Louis R, Faust, jr, ,s of 3 linesi3~6,9~12~1~~1B J2 • Richard Miller Agd:!eri~ acti~~t r~:p~~ailt I '4 27 30~31,%,>914,,4:;,tl. , 5 I or B . 1 ;rders QI full co umns ! ruce Carm1chae l'r1ce1;1: ~ . ) ~ Patrick Page line~ ••n41 Paul Mac Greatly , Jr , cosect10~ umn l5 3close).,, th~t tht e,T adh£olicias co!umns •.••••••.•••• ~ Donald A, Seligman oPre'tJ~Jota t o 1;1o~e ease recolumns·••·••··•·•·· Eugene Chappee 8, are ec 2 o 1c1as ank ii1 columns .• , ..•.•.• ,,, 8 . Emil Kissel 'he top p~rt of this ad page ish Klaus Hill ; close l~ne$ 132 spacaa eac ,r a total of 60~spac&A, lhis Herbert Aldridge George Uveges .s available for 012. Michael F. Flannigan Victor M, Saudek THE WHOLE PAGE I - ' ...,0 Louis Sopata '.s available to one customer for 0 L price of t50 •. George Congdon .i:: 11. Frank Zaic Stephen Baldwin wi not emphasize s.ny chem'h to ra hie advertisers will a Those not lis~ed are those who . ~, 1 or power nuclear Poverplanta Thie kite shown will b1 sent to li~ht ~ystems, out we fol w 11 1 12 ~erpsquare inch used. Widph misplaced their letter to L&S ou Jith bridle and line Sliv11 acclpt advertisements that sel 1 ht are lass than cQlumo ~of, or thought they were going to nct n a reidy-to fly conct1t1on 1ngine1 that can be used in L& w· 11 be char ed l'or i ins. . . i¥· tidtfi Leo~th wfll b, ~,aeur- keep their spending low and slow o taditl ntee ,a, Naede vour 18 co~v, ted ~,stems, Such sy•t•me poun es ine, ~a11 ar,a 1s will hen b ref,rrect to the new )d exac~1 . ~!ngth multiplied by *****The best way to keep your 12 square feet; chord 4 ft; the magaz n• Mo orgl1d1ng. 1 1 Ridth ;~p&j pir~t~~· hs.1 no assembly nor dias.aaembly ~~~~~~~~~~~~~~~~ 2 expenditures low ia to eoak up ~ j~ngth Char e@ 2i the vibrations from Low & Slowl I and simply rolls up for storing Reverently: 1" The sail is blue polyethelene, Easter has a message for L&S: 2" i" SEND $6 or more for 12 or more 211 1 11 issues @ 50¢ Find that letter The three rib~ full_-length &_?'e __ Dhcipline I fa.eting and perofor optimum liTe, Sinc1 $4 veranc1 brings the ~ise and the We are waiting to hear from ~ taped 59 Dudley Ave, Vanice,C! 90291 longed-for Ascension, .

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