Low & Slow Issue 3 1971 by US Hang Gliding & Paragliding Association

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Archaeopteryx was one of the first birds. It had a large brain case, Indicating the sort of complex nervous system necessary to a flying vertebrate.

LOW & SLOW is open to the light o heart who deeire to fly near home with a seat of joy. Low & Slow members share facts and fancies freely without the constraints of too much of anything, especially gravity. Members are entitled to all pri-· vileges, rights, freedoms, and recognition without chargesbeyond the $6 that pay for all including 12 consecutive issues of Low & Slow (Min. 20 pages, once a month or faster). Join us: 59 Dudley Ave., Venice, CA 90291. But more importantly: DO participate ••• send in your dreams! baked or not ••• we 1 ll eat it and discover brand new worlds of ow and slow flight I Correspondence is our means, perseverance is our habit, hope ie our tow, Infinite Free Flight is a goal and End ••.•••• Practically and playfully we humbly a:(Jproach that End; indeed, in a most humanly beautiful way we climb the ropes of snakecharmers, slide down kite lines, develop transcontinental zeroco~t flight systems, say brother to birds, and then train our children and friends to praise the breeze as it gives us a ground skimming respite from our daily labors. Policies: Any photogra~hic materials accepted. Will return at your request. All articles and materials contributed gratis. Plan B people please send in $4.50 for L&S 4-12. Plan C: $5 for L&S 3-12. See 2.20 for ad rates, see 3.20 for samples. Warning: Do not jump off shear cliffs; don't fly higher than you are prepared to fall. Learn before you leap. Fly joyfully. L&S 4 will have fine doings. L&S is in need of a lar~er ga~gle. Do your friends the service of telling them that I.&S is flying. GOVER BY CONGDON: George 1iCondor" c.f. J.20 which see: Brett ~rul!lhardt Congdon of CA,rendition sketch of T. V. Czakowski ~-N • 1!~/??sPrivett 1930 "All American Glider" hanger. Rod Chima Cg~gk Slusarczyk Commercial production model. Thanks Raymond s •. Buchanan Dick L. Hinkley Robert Nadich David Rimmer Copyright by Joe Faust, 1971 ~e1ry RSttmii Ni chi Steinbrecher All rights are re~erved Contri- w=1 1•. a Eenvuryd. John L. Knox • i iam • an iver Fred Millard buted_articles are not paid for Jordan Tanz Rod Crandall f~d L~!v1nsi~t: Lo;o!t~i~:tf~gr ~~~ ~~~ai!cM~~~e Alfred J: DeRenzis Bob Mor•·1son • retain all rights beyond use by George Oflesby E J To;.er Low & Slaw. ThaP.k you. Hugh M. lack ". • • 't'edge~ Rooert Hoffmeyer .:.: · · '"

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LILIENTHAL 1 S 123 rd BIRTHDAY P.ARTY Sunday, May 23rd, 1971

still subject to last-minute change, are as follows: We will meet in Capistrano Beach, at the Camino de Estrella off-ramp of the San Diego Freeway. Matters will be quite informal and we will count on your enthusiasm and good humor to help smooth the rough spots. At the very least we will be able to erect the hang-gliders, kites, hanging man-powered machines on the spot, get acquainted, and exchange ideas in the time-honored and somewhat slippery fashion of air pioneers - that is, with a great deal of exaggeration. Flying accommodations are our weakest point, and there still remains a chance of a site change or an alternative meeting place. As it is, there are two areas within easy walking distance where flying is possible. A prize is offered for the best model hang-glider, which must fly, so if you can't finish a big one, bring a littl.e one. We suggest one inch/foot scale, as several already exist in this proportion. A prize is offered for the longe.st duration flight of the day of a free flight self-launched, piloted, non-fuel using hang-glider (except food fuel for the pilot). Wing-tip guiding assistance may be giv~n by helpers for a moment at launch, but flight should not be impossible without their assistance; they may not provide thrust to the pilot or to his wing. A separate prize for the same event will be given to a mailed result for any pilot performing the flight on the same day in someplace not in Southern California. All pilots are 100% responsible for their own doings; Low & Slow takes no responsibility for any flight actions. Anyone who sustains herself or himself in the air by any Low & Slow means shall be awarded a Low & Slow application for flight recognition to be filled out and submitted for acceptance for permanent recording in Low & Slow. See issues of L&S for the hundreds of .ways and means! This recognition offer is good always. Your name and address will be published in L&S along with nature of your L&S flight. Upwards of 1000 people have bought plans for "Hang Loose" and about 200 of these are Californians. This will give some idea of the degree of interest. If only a small percent of these complete machines, we should assemble more hang gliders at one place on the 23rd than have ever been brought together before. In addition to projects in the possibility or planning stage, there are a fair number of machines complete. We hope to see a squadron of biplanes, several high-wing monoplanes, a flying sailwing, a few Rogallos, a giant Para-foil, a sky kite train, an Allison Sled, and at least one tandem monoplane adaptation of "Hang Loose." Among the items you might care to try to remember to bring are: Food and water Material samples Crotch protectors Light deck chairs Knee pads Helmet ~ L & S flying system Kites g1oves to~ watch Tape Dwyer wind gauge String and rope Plana & photographs Drawings & sketches Sweat arrestors Camera (help L&S) Fragments of work Wind streamers Model hang-gliders Model kites ~~ ~ ~~. ~~~ . To know alternate plans , if such arise, check with one of the following: Joe Faust, Venice (213) 396-3423; Mark Lambie,Irvine (714) 833-3718;or Bruce Carmichael, Capistrano Beach (714) 496-,191

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DANIEL F. POYNTER "Slope Gliding" really got off the ground in Lake Placi~, New York when more than one hundred jumpers lined the Olympic ski jump hill to watch and take part in the low level flights •. The activity consists of inflating a canopy and running down hill until one becomes airborne. It is somewhat akin to parachuting except that it is less expensive, eliminates the anticipation of exits and openings and does not require repacking. It should not be confused with para-sailing where one is part of a tethered kite and subject to its dangers of darting, catching and crashing. The Wright Brothers were running down hills in Dayton at the turn of the century testing their new flying machines and many early aircraft designers used this testing technique.Dave Barish is credited with reviving and further promoting the activity as he worked with his Sail Wing a non-rigid glider. He has made numerous successful fligh{s at several ski slopes across the country. All that is needed is:i.hill with a slope steeper than the glide angle of the parachute;the landing portion of a ski jump hill provides a suitable area as it is very steep, clear, well maintained and has steps and usually a road to the top for the return trip. It was found that it is desirable to have two assistants to aid in the launch. The critical stage is when the canopy ascends overhead and begins to lift the pilot off the ground because at this point he loses traction. The trick is to sense this point and to time it to take place past the crest of the hill and then to pull oneself up in the risers and bend the legs. Once airborne and pulling away from the hill, one may relax ~nd enjoy the flight. A launch assist may be provided the pilot by pulling on his harness or a short line and towing him to the crest of the hill. Steering is best accomplished with riser turns than steering lines as this provides slower turns with a minimum of added sink. Usually the canopy flies straight and requires only a minimum of correction but a cross wind will require quartering which reduces the glide angle relative to the slope. Landing {s no more potentially dangerous than parachuting though some "road rash" may be encountered if the pilot loses his footing, doesn't quite become airborne and slides to the bottom. Normal jump equipment such as helmet,boots, coveralls and gloves are recommended. The potential of slope gliding has yet to be fully explored. As techniques develop, it is possible that the activity might prove useful for inexpensive accuracy practice. In any case, it is an entertaining activity for days with low ceilings and it may find wider acceptance than parachuting since it does not tnvolve jumping_fro~ an ~ircraft or the anticipation of openings. Instruction is brief and most of the danger is eliminated. In fact, those incapable of learning tend to weed themselves out by being unable to get into the air. The warm weather potential for ski slopes has not been overlooked and like surfers, some slope gliding initiates are already looking for that bigger, steeper hill. It has been theorized that "dune soaring" may be possible on beaches where an on-shore breeze hits the dunes and rises creating a wave of air upon which one might "wind surf". So slope gliding and soaring might introduce more people to, and persuade them to try, parachuting while providing an alternate related activity to the parachutists. Copyright 1971, Daniel F. Poynter Further comment and inclusion on the above, see next page •••••• see J.5

SLOPE GLI DI NG by

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cf J.4 ED: Included in Dan's article were six photos with which were the following captions: 1) The pilot is assisted in setting up at the top of the landing hill at the Lake Placid ski jump. 2 ) As the pilot strains against the risers, the wing climbs overhead. 3) When he reaches the crest of the hill and the wing is overhead, lle lifts off by chining himself on the risers. 4) And he's airborne. This is Ted Strong's wing: Aeolus III. 5) To launch the Rogallo Para Wing, the pilot must pull on the front risers during launch. Here is an excellent flight. 6) The Para-Commander's glide angle was too close to the angle of the hill and though the pilots became light-footed, they usually ran in very long steps to the bottom. Dan Poynter added for L&S readers: "The problem is that the gliding requires a wing with more square footage than one for jumping; Para-Planes are too fast for slopes." ED: Thank you, Dan. Fellows, let's find some wind, use a parafoil made with just tape and polyethelene and slope soar! Try big wings of inexpensive materials. Who will be the first to make such a L&S item? Paul Block, a L&S member, might just be the man. ii~*4*.****~*****~***~*****************~*~****'4**~**-***·**·~4**••**************~

Below is a sequence of one type of man-powered flight system converting into a gravity powered system. One shot shows a woman powered action; If you 1 ve never been kit.ed by a womant well ••••

3.6 THE RUNNING, FLYING, LEAPING, JUMPING. GLIDING MACHINE -orThe Irreducible Minimum

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by Richard Miller

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n Volume. 1, Number 1, our editor has provided us with a rich list of low-and-slow aerial methods and machinery on which to exercise our imagination. Out of this cornucopia, where there is certainly material enough to last us all for a long time, I have plucked one of the most attractive items, the running, flying, leaping, gliding and crashing broad jump. A large part of the appeal of this version of the hang glider is that it appears to bring flight, be it ever so hasty, to its irreducible minimum in the form of the least expensive and most compact glider of all. Besides conceding that such flight is going to be quite short as a rule, we are also going to allow that it will take a great deal of physical energy and skill to complete successfully, that we are dealing more with a potentially glamorous track event than a fullfledged aeronautical adventure. It shouldn't be any the less fun for that, however. Whereaa·the hang glider, as we traditionally think of it, does demand certain physical resources, these are definitely secondary to judgement and skill in pilotage. In the case of the running, flying, leaping, jumping, gliding machine, the order is reversed.The physical demands come first;and the-importance of judgement and piloting skill is greatly reduced by the much smaller penalty exacted for errors._ As a consequence, such an event should provide a sort of half-way house on the way to flight proper, a halting place for those with a keen interest in flying, but a keener one still in athletic prowess. Moreover, gliders of the sort we have in mind, and we are considering wings with 30 to 50 sq.ft. of area,are going to be the least troublesome to build and transport of all flying machines. As a consequence, they will be ideally suited to youngsters with limited resources and skill. In this respect also they will make good training ships. There is one critical building problem, however, and that is the accuracy of wing profiles. In order to achieve flight with such small surfaces,these ground-skimming gliders are going to have to have a high degree of aerodynamic efficiency. A look at Table 1 will show that we have used coefficients of lift ranging from 1.1 to 1.4, quite high values.To achieve such values will require carefully shaped airfoils and smooth surfaces. This, plus the very critical problem of weight and knockaboutability would appear to make foam-and-fiberglass construction by far the most preferable choice. There is a considerable tradition in building surfboards along these lines, so this problem should be a relatively easy one to solve. see 3.7

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cf 3.6 TABLE 1 TABLE :2 Pilot Weight and Wing Area Potential Flying Speeds in MPH At Four LBS./ SQ.FT. At Four Values of CL Total· Area CL Pilot 10% lbs. lbs. 1.4 Wing Loading 1 • 1 1.2 1.3 3.5 lbs/sq.ft. 35+ 34 32.5 31 34.4 125 12.5 137.5 33 4.0 lbs/sq.ft. 37.5 36 35143 35.8 130 13 38 31,.5 35+ 4.5 lbs/sq.ft. 40 37 .1 13.5 148.5 135 Another positive factor is that a 14 140 154 38.5 145 39.8 14.5 159.5 locale should be much easier to 41.2 1b5 150 15 find and maintain than one for 42.6 15.5 170.5 155 44 160 16 176 hang gliders proper. The sport 45.3 16,5 181.5 165 should not be unduly dangerous 46.7 187 170 17 either, insomuch as the jumper-pilot is not going to go very fast nor get very high. The Nature of the Problem With all self-launching vehicles, our central problem comes down to striking a compromise between the conflicting demands ofthe ground mode and the air mode of operation.In the instance ofthe conventional hang glider,the degree of overlap between these demands is sufficiently large to permit some slopping around: you can get airborne in even quite a crude machine. At the point of the irreducible minimum, however, there is no overlap, but a squeeze, and the only way out of it is by striving for the very highest possible aerodynamic efficiency compatible with the li·mitations imposed by weight. To illustrate the problem, let's get down to the case ofThe ground mode of operation, which dictates a machine that is both light and small. It must cause the very least possible hindrance to the pilot during a short, but very rapid run, and pose the least threat to him inthe event matters get out of hand and a spill results. What's more, the relative airspeed of the runner with this glider is going to have to be perhaps twice his ground speed, so on the ground as in the air, minimum drag is going to be at a premium.It is obvious that size, weight and drag are going to have to be kept to the lowest possible values. But if we 1 re going to fly, or make a running, jumping, flying leap at it, we've got to have ~ wing area. As a matter of fact, we're going t~ want all the lift and bouyancy we can get with the meagre material available to us. And the only way to make a small area yield a lot of work is to make it the best small area we can. Table 1 is an attempt (by means of calculations and counsel furnished

by co-spirator "Crash" Carmichael)to illustrate the kind of airspeeds necessary for flight at three wing loadings: 3.5, 4.0and 4.5 lbs/sq.ft. and how they relate to c1 values. Note how markedly the miles/hour drop as c1 values rise! The range given, 3.5 to 4.5 lbs./sq.ft. or less would result in gliders too large and too heavy to permit runs at the required ground and airspeeds, and that loadings higher than 5 lbs./sq.ft. would require flying speeds greater than it seems reasonable to expect from see 3.12

3.8 Mr. John Baker April. 1, 1971 FAA Deputy Administrator for General Aviation 800 Independence Ave. SW. Washington, D.C. 20590 Re: AIRCRAFT DEFINITION FOR LICENSING PURPOSES Dear Mr. Baker: In view of a current patent application and its subsequent business possibilities, I would like to obtain from your office a formal answer giving me the criteria that your office uses to decide when a man made machine occupying airspace, at anr level above the ground, is required to be registered as an aircraft l "N" number assigned), needing a Certificate of Airworthiness and its operator a pilot's license. The obvious question that first comes to mind is this one: Why a parachute jumper does not need a pilot's license or his chute an "N" number even if both use airspace? The chutes now available have glide angles of about 3 to 1 and their operators can affect positive control of their glide path by_means of turns, changes of their forward speed, rate of sink, etc., and under the proper soaring conditions can be made to gain altitude. To clarify my point I would like to list some of the reasons that I think your office has used as criteria to determine when a flying machine is not an aircraft subject to registration as such: A) The conventional aircraft (fixed and rotary wings, balloons, etc.) while at rest in the ground, remain still in flyable condition as opposed to parachutes where upon their lifting surfaces lose the normal flying configuration when reaching the ground. B) In a parachutist's landing no mechanical devices serve as landing gear but instead the operator's legs and feet serve this pu~pose. C) The parachute, to be able to be airborne, needs to be reefed. This means that the main lifting surfaces are not· ready to lift the pilot and can only be made operational by special techniques, like tying the parachute to a tow line or by jumping from a flying aircraft and opening the chute in mid-air. Reefing of a high L/D and fully controllable parachute, on a steep hill slope could get it flying taking off from the slope while a fair breeze is blowing and remain aloft using the strong ridge lift. Is· this a parachute or an aircraft? Still, if this flying machine reached a horizontal terrain it would land via the pilot's legs or some other part of his body and its main liftin~ surfaces would, nevertheless, lose their normal flying configuration. Sullllling up, it is my belief that the human landing gear and loss of noraal flight configuration while resting on the surface, are the the criteria used by your office. Some of the factors that may have not counted when FAA defined an aircraft are listed below: 1) Airspace useage could not apply because sport parachutists, before and after opening of their chute, certainly use airspace in a very exclusive manner indeed (drag zones) and ~o do man carrying kites, tethered conventional Iixed wiAg gliders and gyrogliders. 2) Weight, size or rigidity cannot be a criteria either. Ground effect machines rule this out. We realize that close proximity to the terrain is a must for the ground effect to take place. 3) Gliders, gyro-gliders, parachutes and man carrying kites, when attached to lines reaching the ground (with some altitude limitations in the order of 700 ft. AGL} are also exempted from 11 N11 number or pilot's license requirements. So altitude is not a criteria. 4) Duration of flight or capability to soar, that can be achieved by any of the above examples, may not be a criteria either. I would greatly appreciate your clarification on the matter.

3.9 So summing up, airspace, weight and size, flight duration or soarability may not be the criteria used by FAA to determine what is an aircraft and thus subject to registration as such. I have taken the liberty to send copies of this letter to other organizations using airspace for sporting p~rposes and that have shown a keen interest in obtaining means of flying for the man with a restricted size pocketbook. Sincerely, iiterimental Aircraft Association Patrick E. Page c/o Mr. Paul Poherez~y 393 Cronin Dr. Santa Clara, Calif. 95051 Soaring Society of America c/o Mr. Miles Coverdale u.s. Parachute Association of America Low and Slow Association c/o Mr. Joe Faust Balloon Club of America c/o NAA. Washington, D•• +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++·

Did you know that there is a K.I.T.E. Society of America and another organization called American Kitefliers Association? They complement

•••••••• ,~~~.~~~~r.~~~.;;;.~~!~*~;;~;~;.*~;!!;*!~*te:*i*¥tw:*f2r.~sr2*!frf~,*********·~ !Joes any .kind of BALLOONING belong in l.&S ? Not in the traditional sense. But L&S is going to promote some very special kinds of manned or unmanned free and tethered ballooning. Let us just quickly pass over some of the ideas and let all of us chew over some choice possibilities before we spend too much time on the matter. Some L&S BALLOON TYPES: Buy no gases and use no fuel. 1. Pniuma1i~ hang-gliders, These balloons ~re.struct~rally he pfu ror regular ana uncommon hang-gliding. I.&~ would fill theseand all types without use of fuel-using motors. 2. Pneumatic traditional toy and giant kites that are air filled without use of fuel-using motors, but by wind, breath, or? 3. Lighter-than-air balloons that are obtained lighter than air by means that have no recurring fuel costs. l.&S won't buy gases. a) When a thermal passes, grab it, bag it, and then wait for a cooler or more dense air mass to become the bag's environment. Go free L&S ballooning! This might work well with a super-giant Para-foil: close the front valves as a thermal is being rammed; ride the thermal lift; glide out of it in due time, hut be in a cooler environment with the lighter machine! b) Kite yourself to the very high regions(you do not have to go yourself) and fetch a proper pail of the light gases, jump with your new L&S envelope and find equil~brium at a lower altitude .• you hope! c) Or grab some air near home. Let your parabolic solar rerlecting mirrors cook the air inside your bag. How? Suspend a heatable element inside center. Direct the light to the element, Soon you will be off •• l.&S! d) Grab some of this hot air and be off ••••• Dan Poynter of I.&S p.3.4 reports of his balloon making: "One was black on the outside and aluminum on the inside and almost goes up by itself." Dan, keep trying •••• we are. It has been done unmanned. 'nn1111nnnnn111111n11u11 n nn11n1111111111 n11nn111111111r11nnn 11111111111111 n1111 " " !'"" 11n1111111111" "'1"" ,, 11111111 "" 1111 " " " on 1111 nn

Being out in the fresh air with my aerial systems recently I was inspired to create the following ••• let me share with you: Winter Daringly you approach living twilights of darkened woods ••• While rest is i~~r gift, not death. My beloved quikens to ways of warmth, our fire is lit anew. Your freezing tands permit Spring life to join her freshened embrace ••• ***

Glad am I for you, Winter.

Your courage is rewarded.

JpF 1971

3.10

The above ehou•s the author's grandfather (Tight) in flight ia a homemade kite (/,eft) in 1910.

THE KITES CAM~ FIRST by Malcolm M. Ferguwn • KITES hal'e been a familiar part of our country scene for more than : a <'onple of centuries. Around :!\ew England, the8c were apt to he : diamond-shaped. or perhaps with the head rounded oft'. They are : sprung or bowed slightly to catch the wind, and are sometimes called ' !,ow-kites for ..thi.B. reason. This diamond kite is of andent origin, and is the kind you'll see under .. K" in the old S[)elling books, or to gh-e action to the 1790-l'intage vignettes by that remarkable British countryman Thomas Bewiek, who set the style for American woodeni;ra,·ers and almanac-illustratorsKites caught my Imagination .for an added reason: my grandfather u·ent up In one, and a photo of him thus sm,pended made the eoml,i. ·nation of toy and experiment a[)pealing to me. This element of adventure was present. too. when Ben Franklin and son sent their kite 11[) a thundercloud in a Promethean experiment to see whether the 1 Into l\·t.·i: }:iring w-ould carry that mysterious force, electricity. It <lid. hut In an obligingly small dose, so that the Franklins, helo,·ed of the god8, lived to stir the hearts of their countrymen. The kite's slender string was a most necessary lifeline to earth for tlylng man, or homo volans, jnst as the umbilical link still is neceRsary for astronauts. "'l\·hen there's a string attached, It's a kite, not a i:-llder: and that ls what Alexander Graham Bell sent Lt. Tl10111as :-;elfrldge up in - a gilder-shaped kite - in 1907. So It Is quite clear that through kites the thoughts· and daydreams ot kids and their elders go back in years beyond the free-soaring gliders, the ,vrlght llrothers, the magnificent men lo their flying machines, the aeronauts, and the astronauts. Clearly, a motionless, hovering gull weighs more than the air It displaces - yet It is held up. The t<ignlflcance of what has come to he called streamlining was recognized a century ago-_by an Englishhorn l'nitarian minister, Samuel Hobert Calthrop, who introduced the rrew-racing •hells -America'H first intercollegiate sport - for Harvard lu 1852. In the late l&;os he patented a streamlined train. In racing Rhell3 the slip stream is critically important, but In the locomoti,·es or the period It was inconsequential. Such random efforts, m ..asured In term" of the history of tlig-ht, were definitely cumulative. It wasn't until the 1920s and "30s that the complex nature of the air-toil \VII.II understood; previous efforts had been on a trial and <>rror basis. This Is the way It l• explained by architect-designer Norman JJel Geddes, In hi• oook, Horizons: "An ol.Jject Is airfollt-d wh<-n Its exterior surface Is so designed that upon being projected fhroni;-h the air, a uaefnl dynamic reaction is Imparted to the object 1,v the actir,n of the 11tr. The lift of nn airplane wing Is an excellent

(·Xnmple of a HR'?'f11l dynami<!' rPactlon." Cnrt,,usly, th<' an•w<·r waH availalile in the l!lth C<entury. Ask a few nirm<•n to,]sy arul tlu~y wJll P.Xplaiu it all with ,lrawings and '1iHtlnc-

~:·.·,: lmnd '-"'·stun·ri. ThP. l,:1:-:ic tht!Ory. they will tell you, waH

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83 ponn<l"'l Ii~· a mrmher of a family of S,dss mathemati<·lans, )lanl!'I · Hernunili, in a 17;:s hook. Hydrodynaml..a. It boils down to this: arch the top of a plane "'i111,:, hut make the bottom flat. The air flows more qui<·kly he1w:ith the wing, more slowly ahove. It Is a,;surlng to know that a~gnment nntl ail·plnne alike are now sustained by mathematics ancl wrnd tnnn<>l ,,,·hJpm·c. With inno,,.·n<'e of such mattns In the 18.'lOs. the question aro~<'. what size and sl1a1>e of kite would have a good enoui;h lift-to-<lrni; ratio to :.:Pt a man up In the air? Rememb<>r, these werr bn<,k~·ar,l experiments. These people-In the United States, Germany, Pran,·e, Australia - were won,krlng, just as Leonardo da Yincl did aronnd the year 1;;00, If the flying man should flap the mi>chanlcal wini;s of this hircl-maC'hini>, or ornithopter. As a result, experimenters from that perio,l on were bedeviled with the alternatives of remaining- <Juiet dnrini th«'ir hrirf tli!!h.t, or eng-n1,!'ing in some jumping-jack <"Xrrei~P whi<·h wonl<l S<•mehow translate Into a fllght-su,tnining: fur<'c. It i$ not dear whl'n the first man went np in a kite. It was not my i:rran,Ifatll(·r in WIil, c<•rtainly. P<>rhaps it was an Oriental a ('011pl<• of thonsand y<'ars a)'.!o, for they haYc been flying: them that loni;. Kit<' PXpPrimC'nts \\"("re ne,·<'r confined to ;.::etting- a 111an aloft. hut simply in :O:.t..•(~in;.:- what "·ould

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under various conclition~. Thus. thP hox-kitP

"·as i1?,·entNl h~· an An~tralian nn1ned La:wrence Ilar;.!ravc in l~!l;t This is th(' s('<·orHI most popular kite <"Onfiguratlon. It is reC'lan;.:-ular "'ith 01>en sqnar<> ends, the 1>ap<'r or cloth going around thC' si,l<•s of th<' l'l'<"ta11;.:-le. but lea\'lng a middle for the air to flow In. Tl1is kit" d11<·s not nped a tail like the diamond kite, sin<'e thl're·s an uxial nli;;-11nwnt to n•strain it from yawing and losin)'.! its wind. Kite paper is smooth, tough, and light. Silk is used, too. sinl'e it is lil!ht. flexiblr, and doesn't let the wind through. l\l~· daui:rhter B,•tsy and I tried n store-boughten rubbery plastic kite last summ,•r 0111 at the Isles of Shoals. '!'his kite was hat-shaped, and Its surfa<'e rippled with the hn<'k edge of the hatwing flappmg slight!,·, whi<'h is !'ll!l1><ise,l to be good, aerodynamically. '!'his kite bas a k<>el inst,•a,l of a tail, and the string is bltcb<>d to it. ,vhat with the Islt>s of ::-;hoals nin<> miles out in the ocean off Portsmouth, New Hampshir<', onc> <'llll count on a good breeze and few obstacles. The first trial W<' pnt out half a mile of string as the kite rose o,·er Star Island and then n,·ro~s the co,·e to Appledore. The second try took the kite up and ofI to "'bite !~Janel. It was Interesting to watch as it went strali:rht 1111 in the air that was to an extent helcl to the Island, and then brok<' ont o,·er the oC'e:m, and finally up again o..-er the other Island with its lig-hthouse. Before we were done we had let out llterall)· a mil<> of kite-string, and the line was running almost parallel with the snrfn<'•' of the water. ,ve <"Onl<l .see the kite; which was well a,,·ny from wh<>rc we lost sight of the string. We were not particularly disappointed to learn thnt we had Sl't no record, but were interested to learn that experiments nsln1,: piano wire and a string of kites had run out to a distance of 10 miles. Our kite twine was Inexpensive, strong, and ofl'ered le"s aerodynami<' clrag than thicker piano wire. 'l'here is currerrtly a ,i;ood deal ot kite a<'tll'ity, though It tak<'s open ~paces, nnd Is not a city game. Ahout one out of eYery four or fi,·c> issues of the Patent Oflice Gazette lists I\ new kite cl<'l'lce. some hP!'ng hardly better _than a kid's day-dream of, say, lnexpensh·<>h· C'asting n fishline where you could not otherwise, or g<>tting l<>ad-Mrings across bottomless gorges to start brldge-hulidlng. NeYerthl'il'ss, ,·alhl metl'orological experiments go back to .a decade before Franklin·, ad,~enture. . . . . Notable among <"Urrent act!ritles Ill development of a '.'par~foll" which combines kite, parachute,. and airfoil, which· means: it ,•an be controlled from the ground like a kite; it can be used as a fall-bn•nking device Just as paraclmtea have. been since early ballooning clays - In. turn, two centuries after da. Vinci's sketch; It has manlpulnhle devices which by remote radio control can alter the wlng-sha1f<>d structure's characteristics. lta · Inventor Is Domina Jalbert of Boca Raton, Florida; '.rhe ·possibilities Include positioning cargo.<'S in airdrops of up to 500 pounds, and eaectlng airplane pickups from ship Installations. . If these are too sclvance<l applications, perhaps you <'an elthn find the store in N'ew York City (where else"/) which specinllzl's In kite supplies, or mnybe you might wish to join the Intl'rnatlonnl E:lt<'fli<'rS Association 181 Sea,·iew A,·cnue, Premium .l'o!nt, N. Y.). But th,'n. It i:;.n·t nec.-<·s:o:;ary to jotu anything or seek sophistirnh"d ~ear. Po:,:;sihly :n,11 may wii-.h to g-et yourself apo1ui:ored, howe,·l•r. by one or 111orc kith•. It':s niore fnn thnt way!

Repr,~ Tt:D

W, TH

P[Rtnl55/0/t/ op

fll..mJJN Ile) PU.BJ.IN., /II,, 11. JI ·

Tfft: OJ.. D

PfiRm.t:12 15

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3.12

anybody. Our goal is a glider with the highest possible wing loading that will permit equilibrium flight over at least the majority of the flight-leap trajectory. Only by going to the extreme, and by using high-efficiency apparatus, can we hope to get the size down to a point th~t will permit running speeds high enough to launch a glider with so heavy a loading. Four lbs./sg,ft. On the off-chance that our calculations are within 20 to 30% of the situation as it will come to exist, let us use 4 lbs./sq.ft. as our jumping-off spot in this ground skim of fancy. Let us further, in an arbitrary manner, allow 1oi of the pilot's weight for that of his machine and the sum of these two figures (see Table 2) as the basis for our wing-loading calculations. This 1~ brings our problem home to us, for we see on the one hand the difficulties of trying to run full tilt with a contraption equal to a tenth of our bodyweight, an~ on the other of attempting to build anything flyable using so little material. It is perhaps optimistic to imagine that we can hit the 1~ figure, but it would be one to aim at, and all would suffer equally the handicaps,on the ground and in the air,of the extra pounds. Once we have the finest glider we can design and build, we are st~ll faced with the not inconsiderable problem of reaching a relative airspeed, while running, on the order of 35 mph. There is little do~bt that such speeds are well beyond what even the strongest runner is,capable of, and that some help is g~ing to be required to get up st~am. Of the numerous possibilities the simplest and most satisfac, tory would appear to be to use gravity in the form of a short slope leading down to the take-off area. The starter would then back up the hill,much as a pole vaulter backs off from the bar, until he felt he was in the exact spot necessary to give him precisely the speed needed for the best possible launch. This method has the further advantage of being self-regulating. If he uses too short a run, the ju,per fails to get adequate speed. If his run is too long, he tires hiiself unduly. If he's too slow, he's not in the running. If he's to6 fast and fails to rotate in time, he cuts his flight short. 1f heis too fast and finds he must rotate too soon, he will fail to hit the take-off board and be disqualified. ! (The take-off' platform itself might be a small portable affair consisting of two parallel boards held apart by light springs so that the pressure of the runner's foot on the top board closes a batterypowered ((ED:could L&S groups use wind generators, Richard?)) circuit and activates a buzzer. Thus not only the judges, but the contestant would know when a start was good.) Given a short downhill run e~bodying enough of a drop, a runner should be able to reach his maximum running speed of 20 or more mph even in the face of a 15 to 20 mph wind and so have a certain margin of airspeed by the time he rotates into flight. Everything would seem What's going to proto depend on the speed at the moment of launch. duce long flights and win competitions is the number of miles per hour airspeed in excess of the stalling speed that the runner can accumulat,e at the moment of take-off. This, and flying skill. see J.13

Elements of Design cf 3.12 The factor which is going to rule all others in the matter design of the ground-skimming glider is that of weight.Fortunately such . i machines are simple - a set of parallel bars hung beneath a wing, a I. boom and a simple tail, and no controls. Also, the strengt h requirements are not going to be critical. A structural failure mighi result in a bad fall, but on the average this should be no worse than a similar experience on the high bar, or running hurdles. These! two considerations are greatly in our favor when we attack the probl~m of airframe weight, but we still face some tough sledding. i The wing is the biggest single unit we must deal with, as it ;will probably account for something like 75 to 80% of the total air~rame weight. If our primary consideration in the design of the wing lwere to achieve the lowest possible weight,we would be inclined to us1 low aspect ratio and marked taper. For a glider in which we desire the I • highest possible performance, the idea of a low aspect ratio Fing does not at first seem too attractive an alternative. There are !some special circumstances that apply here, however. To illustrate, let us take the example of a wing with 36 sq1rft. of area, just about the size necessary to accommodate a 130 lb. ran, and slice it two ways, first as a high aspect ratio (9) wing wifh a chord of 2 ft. and a span of 18 ft., then as a low aspect ratio! (4) wing with a chord of 3 ft. and a span of 12 ft. If we now assure a flying speed of 35 mph_, or 50 ft./ sec., we find that by using the larger chord we move from a Reynolds number range of somewhat over half a million to almost a million (.6 to .9 million). This is a particularly productive increase, as it chances~ and the conseq~ent gains will in some degree offset the loss in span efficiency, :but some calculations and experience will be necessary in order to se~ how best this compromise can be worked out. The weight savings possible with the low aspeot ratio wing alternative proposed above will not be restricted to the structure of the wing alone, but will extend to other areas. A wing of 18-ft.~pan, particularly a very light one, would certainly need something in .the way of struts in addition to the vertical members connecting the ~ang bars and attach at points 2 ft. out from the center, thus giving a wing of three bays of 4 ft. each • .l third strut,attached to the un~erside of the wing just behind the pilot could then be used to tie t ogether the parallel bars and tail boom. I Stability Just as in the case of performance, so there is a trade-off ~etween stability and weight, and the structural element most affecfed in this case is the tail boom. A boom a bit on the long side, plus generous surfaces, would seem to be what we need. This would be heI sirable first to trim out the high-lift sections we contemplate using to obtain large CL values, and second,to provide as stable a platffrm as possible for the pilot-jumper during his all-out effort to attrin maximum speed. To what degree this stability could be compromised and the boom and tail cut down to save weight, experience alone w 11

- ........

j. 14

cf 3.13 tell. Insomuch as we are concerned with a glider designed to fly in only two dimensions, those of a vertical plane, and insomuch as we face the po:ssibility of dropping into the stall range during a leaping,flying, gLiding crash, our requirements in directional stability art: going to be: unique. Perhaps they might best be met by a bit of dihedral and a i generous vertical surface intended to keep the ship on its flight t~ack while airborne, and dead into the wind during the ground run. , Light aluminum tubing would seem a good choice of material for I t~e handful of fuselage pieces and the tail boom. If the boom is to be; very light it might be worth while to incorporate a spring-loaded axjticulat.ion to relieve excessive loads. The fixed surfaces at the en;d of the boom could be constructed of light styrofoam frames covered with silkspan and doped. These might plug into the boom or somehow be arranged for quick replacement in the event of damage. Finally. Skill Even with the best equipment, a properly graded hill, and just th e right wind velocity, a great deal of skill is going to be require~ to hit the take-off line at maximum speed, launch oneself in just thie proper manner and complete an I extended skim under full control. It: is easy to imagine a dozen or two ways to fail in such attempts• I but the successful flights would seem to fall into three categories: I *1) A take-off at high enough relative airspeed to assure equilibri~m flight over the entire course, followed by an arching trajectory during which the pilot first converts some of his kinetic energy into potential energy by gaining as much altitude as he feels suitable, then uses this altitude to extend his flight as far· as possible, rotating the glider to higher and higher angles of attack as airspeed diminishes,and landing under firm control. This alternative would seem to offer the best opportunity for long flights. *2) A situation in which the wing loading is too high, the speed too slow, or the efficiency of the machine inadequate to permit true flight. Whereas in the first instance stability comes in the main from the flying machine, in this case it comes from the inertial force of the jumper's body while he's off the ground. In short, he becomes a winged projectile, and although the wings contribute something to the length of the jump, they add very little to stability. ~t first glance, this would not seem to be as much fun as number one. *3) This alternative would be a hybrid of numbers one and two. The pilot-jumper would leave the take-off board with airspeed, but stall somewhere in mid-flight,ending in a loosely controlled crash. This would perhaps be the common, or garden variety 1

of flight. Owing to the small working margin of speed, success in such flights witl be separated from failure in moat cases by self-assurance and as~ertiveness on the part of the jumper. It does not appear to be the soJit of thing one can launch into half-heartedly. The first moment

see 3.15

3.15

cf J.14

off the starting board would appear to be a particularly critical \ime, with the possibility of stalling on the one hand, and on the ot)her running headlong into the ground. Consequently, a start over water, say at the edge of a lake or pool, might be worth considering. It' is also obvious how ideally such a sport would be suited to the oceanside l.d e where the slope of the beach and the on-s h ore breezes wou ld prov:1 the best imaginable conditions. And those who got as far as the s~rf line could temporarily disconnect the fuselage and use the wing to; surf back to the beach I *'"" Variations on the Theme The irreducible minimum glider need not be restricted only to use as a broad-jumping machine, of course. It might just as easily bei em, ployed .in high jumping, or in a kind of vertical slalom in which the pilot goes over and under subsequent lines. One might also envisfge a long, extended skim made possible by installing the take-off course just far enough back from the edge of a gradual slope so that the longest flights could be extended by taking advantage of the lowered ground and gain significant additional distance. ! In sum, the possibilities are very great and it only remains make a start. END ED: Thank you, Richard. I started *** practicing this type of flight n-

i J

ly 17 years ago with a pair of wings each 2~ feet long and with a chord of 3 inches. Because my wings are.of poor airfoil design the I best performances have been the following: Distance: 21' 1"; Height over a bar without hitting the bar: 7' 2". The world record for this size and shape of wing is now 7' 611 • The distance record is over JO feet by a fellow that used some weights while he was leaping - he let go of the weights during his flight to obtain an inertial reaction :to his distance advantage. Track rules would not accept it, but l.&S will. I am anxious to get a better set of wings and use a two-foot take-dff for achievinl? new horizons. See l.&S 4 for Minimum minimum fli,,.ht ********************************************•*~******~1~•. i ~t********** has be~n di!ficult getting Miller o~ photograp~ic paper, but be~ow left we find him off the ground on a mild slope. lThat aluminum "ib ~ail Rogallo is being !epaired_f!Om ~ind storm damage) Note the arch in the back-a paradoxical position if one were landing. A back relst prevents shifting C.G. at the top of the body so the legs must do all th 7 shifting. I would lik! to s:'e ships ~hat do not have a back resf !h1ch can become a head-hitter 1n some kinda of landings, especially if feet are bacl( as shown on bottom left. Bottom right shows an unknown learner making a safe landing. ( ( Share your photos I)) i

lynamicSoarlng'

by Richard· Millor trc,_a_ his 'tit.bout Vidble Means of Support

moet :

LONG AGO as 1883, in what was certainly one of the oteilabout its longitudinal l!lds a lirie near the center of presinspired-comlnents--ever- made on-the-subject, LorcLRs.y!eigh_ ~•um...The1lannstdt Geh_~imra_t, also of 1922, featured such a sysed that soaring flight required either a wind tbat WM not tern. In flight the elevator of the Geheimrat was to be left locked izontal, or one that ·was not of unilorm velocity. Today, the in J)09ition and the longitudinal control, as well as response to ;er part of a century later, we 8""Jil to have no ~ g e favorable gusts, managed by manipulation of the wing, Only in t could be used to argue against this brilliant hypothesis. , ,the_l!Vent of. \l,e pil_ot finding himself in an. attitude from whi~ WINDS NOT HORlZONTAL-slope winds, thermal upcurrwta, 11iacould oot reci:m,r by use oft!iewiniJalone would the elevator .,ergence zones and evening valley circulation chief'' amonB : be brought Into.play. . m - are by far the more easily exploited of the two typee ·and i 'Ibe w!ni-oontrolled -gliders, although probably superior .to ·e been extensively explored and analyzed -by - glJdc ,pi!ot1 ~ · ~presentsd muctural problems that were not easily :e Rayleigh's day. WINDS NOT OF UNDOIDl'VKLOCZn_ ~ ~- imutered, The forward tall of the Ent• was one way around the recondite matter of dynamic soaring and have· proven 'problem. Another ~ Iha Blleron linkage usec1 l!!l • ~noplane be considerably lesa accessbl to · d bis chines than 1 glider designed by Fins«arwalder and Von Loss! and built by the ,a;e of the non-horizontal v~e~y, N:"eri:iess d ~ c soaring i »avarian Aero C!ub in 1921. In this ah!~ changes .in the .angle 1 long been one of the more romantic concema of gliding of attack of .the wm.g were effected by rotatin~ bo;h ail_erons in the rimenters. In the earlier days of the sport; when many theoriee _ same c1Jrect10~ while lat<;ral _control ":'as ~t_amed m the usual d yet to bo tested, and before the ability of the albatross was as ~ e r , by aileron rotat10." m oppo~1te directwns. . Jy appreciated as it is today, the teclmique of dynamic BOSiing For about a decade pnor to the hme the Ente and Gehe,mrat ,upied many an astute theoretician and many tew Orthy - were built two very remarkable men, one a German, the other 1tributio11J1 to the art were made no French, had been devoting considerable attention to the matter The Germans, whooe early ,;.,ntributloM to gliding were 80 ; of d ~ c soaring. Both of them produced ~ginati~e soari.ng , in advance of other nations, did the majority of the ploneel'Ul1l · machines and one. some remarkable results. L!-l'e theu- prem':" irk and made the gr t=t . d .. . W lf contemporary, WeJ.SS, they have been largely ignored by their es = progress m ynam,c soaring. o •: , ibl beca h f . ah d f h . t' ng Klemperer, who we have met elsewhere in this work, hsd a j posterity, poes y use t ey w_ere so ar ea o t eir rme 1g-tirne concern with both the theory and practice of dynamic that we have not yet caught up with them, ~ht. It wae his contention that rhythmic oscillation of the eleIt ~.ms q~te pro~able that Dr. Ma~n, the Fre~chman, tor, made while flying. through vertically pulsating air, could! was fanuhar Wl~ the ideas of Lord J;ayle1.gh concerrung the eld "an optimum power gain a little in excess of that natural: nature of. the wmds n ~ r y for soaring fl1gh! and also conin which would be derived from inertia aloneu-p 1'din th 1 versant wtth the. work of his own coui:itryman, Pierre ldrac, who lot could anticipate the incipient gusts and react a;: 0 !tel el. _investigated the ?'echa~cs of the soaring flight of vultures an~ them! . · p pr y of the albatross in Africa at about the tum of the century. In · Klemperer's third glider, the Aachen Ente of 1922, was built, 1914 Magnan produced two gliders, one patterned after the. vul•ecifically to experiment with gust flying, It wae a canard type, i lure, the other ~ter the ~lbatross. The fust of these two ghders .at is with the horizontal tail forward of. the wing. ·This- con•: ev~n featured hp slots, six to .a panel; second had. an aspect :uration was adopted in the hope that frontal gusts, acting oni ratio of 15. !30th h?d cantilevered wings,. streamhned fuse1e forward surface and momentarily increasing the. angle of at-[ lag~, convent10nal tad surfaces and were, withal, very modem .ck of the wing, would tend automatically to utilize variations in looking. _ . . ,e relative wind. The tail-first design was considerably lees I . , As proved t~e case with his German counterpa~t, Harth, Magttisfactory in practice than in theory, however, and moveoveri nan s wo.rk was mterru~ted by the Great W?r. But ~n 1921 he pr~lffered from longitudinal instabilit . duced his type M-2. Like ~he pre-war des1fll;", this was a cantilever monoplane., Perhaps its most outstandmg feature was the KI emperer ,s canar d co nJl gura 1ton was onl y one of a number · -· T · · r methods used to try to trap the elusive gust gradient. The method Ma~n devised. to uh 1ze ~onzontal gusts. The wmg lethod which seemed to have the most in its favor, and the one . ,halves wer~, m effect, shd over a pall' of r~ngular box-~eam 1ost com.mo ]y I cd t t u, , that , . spars to which they were attached by sets of springs that penn1tted n emp oy • was O moun "wing 80 --~t PIV• each pan.el to respond to chan~es in the relative wind and to

, more

<Jfiapt itself to atmospheric variations. The pilot's seai"of the M-2 was so included in the elevator linkage that a forward stick movement not only depressed the control surface, but -also moved the pilot forward in the cockpit as well! Like so much of the rest of his work, Dr. Mngnan's nppronch to testing the M-2 was p,eeminently practical. The glider was suspended on a wire hung between two poles in a manner that kept it tethered and facing the wind. Horizontal and vertical gusts in the immediate vicinity of the glider were monitored by dynamemeters and the readings, presumably, compared to the recorded weight of the glider from moment to moment. Some manner of flight tests were made, but these appear to have been inconclusive!.

ex-:

ti:•

FREDERICK HARTH, if we are to judge by the results he obtained. in the art of dynamic soaring, was not only several strides

ahead of Magnan, but was one of the most original ond pertinacious of all aviation pioneers. Harth wns a Bavarian, a native of Bamberg, who achieved more significant results, it seems, than anyone else who has thus far attempted dynamic soaring. He was an architect who appears to have been attrncted lo Aying primarily on account of the mechanical problems it presented. He began his career in aviation in 1910, at the nge or 44, on the gentJe slopes of the Heidelstein in the RhOn Mountains near his home. Assisting him in his experiments was a younger man who was to achieve a certain measure of success in the world of avia· tion in the years to came. His name was Willi Messcrschmidtt. Harth and Messerschmidt! were active until the bcginnin~ flf the first World War, did some work during the war and. like Magnan, returned to their pursuits when the slaughter ended. Although toward the end or his career Harth built a glider with an enclosed fuselage, the majority o[ his machines were of the primary type, with open trusswork between the wing and tail surfaces. _It seems fair to guess that it was Harth who originated the wing pivoting arrangement used by others later. Control of the wing was effected by two sizeable levers through which gust loads were transmitted to the pilot and by means of which the pilot altered the angle of incidence or the wing as he saw fit. Not only could the required incidence changes be made by moving

boili

levers in the same direction simultaneously, b~t the glider could be turned by using the levers in opposition. As early as January-of 1914, and again in 1916, Harth made successful flights in gliders of his own design, in one instance staying in the air for 3 112 minutes! In 1920 he made a number of

aee

3,17

w :..

°'

of 3,16 tions that mwit have been necessary by the pilot, were a potentially dangerous combination that resulted, in 1921, in a serious crash. Harth was badly hurt, particularly about the head, and although he recovered adequately to resume flying he never again matched his achievements of earlier years. Harth's retirement from activity at just the moment when Klemperer, Martens, Hentzen and the other practitioners of slope soaring were having such spectacular successes on the Wasser• kuppe, and with a form of gliding which ultimately demanded a great deal less from the pilot, put his efforts into eclipse in somewhat the same manner that gliding itself had suffered when the infernal combustion engine helped turn the attention of the world from the glorje;; of motorless flight to that cruder adapta· · lion of U,e airplane that was inaugurated on December 17th, · 1903. Taken all in all, Frederic Harth seems to have been one of . those individuals who, in his accomplishments, not only out-. stripped his· contemporaries, but the just desserts such acconi1 plishments merit.

· W~lf;Hirth at 1he ~ontrol1 of one of F·redaric Hcirth's g\lden

of the s.ort that established a world duration record In 1921,

the Tibetans or the Aztecs or the Arabs or some other heathens didn't beat him to it, may have been the first man in history to do so. It is not improbable to assume that Wolfmuller, who was, incidentally, a pupil of Lilienthal, realized that dynamic soaring could be achieved by one of three methods. Outwardly the simplest of theee, yet really the most refined, is to devise an aerodynamic form that modifies itself constantly in order to uti~ lize gradient energy. The second is to commute between two layers of the wind, alternately storing and expending energy in the passages back and forth, as the wandering albatross doea. The third is to build a flying machine of such dimensions that it effectively spans two layers of the atmosphere and utilizes the velocity gradient between them in much the same fashion that a sailboat, with its keel in the water and its sail in the air, works between two elements. This is what Ing. Wolfmuller did. Although on first hearing this idea sounds a bit outlandish it is really so eirnple that anyone can do it with material costing only a dollar or two. The magic ingredients are two kites and, some string or wire. Provided that there is a sufficient gradient between two layers of wind, or wind from two di~eclions, the kitee can be made to sail off as a set simply by tethering them to opposite ends of a suitable length of line. Once released they will· , rise through the gradient until their weight-plus-drag is equal to : the force generated by the stratum in which they operate, muc)l ; as a balloon finds its point of stability in the atmosphere. Such' kites, by properly rigging them, can be made to sail across the wind. The idea of tethering two gliders together, nose to nose, and flying them in a similar manner, has occurred to a number of people. The problem of an adequate gradient would seem to have been solved by the discovery of the jet stream and someone may yet manage a cross-continental soaring flight by this intriguing means, provided a few minor problems can be solved.

flights of up to 6 minuies duration over a •_lope with an incline of only 2 to 3 degreea, hardly enough to fu;11ish a elope w~ No REVIEW OF DYNAMIC SOARING would be complete without ·adequate even to keep the ultra-light machmea of Harth au• reference to a' still earlier experimenter, also a Bavarian, Ing. borne. In September of the following year-Harth'•. 55thl-he Wolf muller of Munich. In 1909, a year of inestimable consequence wae back on the Heidleetein.- At 8:30 on the morrung of the. for aviation, Wolfmuller built a glider which, it is not difficult to !3th of that month he flew for 21 minutes and 30 secon~. Dur-! believe, inapired both Magnen and Harth in somewhat the same ing this flight, which constituted a world record _for duration, ~e, manner as Harth's successes seem to have inspired Klemperer attained an altitude of nearly 600 feet above his take-off po~t and the buHders of the Geheimrat. Like the machines of Magnan, and ranged as far as a mile from the spot he began, and !emu-. it was a streamlined mono])l'!_ll_e v.:ith a cantilever wing. It was nated, his flight, • I : evidently meant tO be adaptable to either of Lord Rayleigh's The German aviation magazine Flugsport called attention to :·winds, but it is to those not of uniform velocity to which we turn the fact that Harth's flight had been made over a plain, a fact I -: our interest. that would eliminate the hypothesis that the pilot had uiEd The wing of the Wolf muller machine, which had a span of slope winds for his feat. There ~as s"':m°';1 to ':"' _very little d_esire some 32 feet, wae patterned after that of a soaring bird, having to give Harth credit for dynamic soar,ng m ~lS 1~tan"'.'. It ~· of U,e six slots per panel common to U,e vulture. The wing seems course, quite possible that he contributed with his marupula~!one_, to have been rotated at the leading edge, not near U,e center of -;:;nly a fraction of the energy for such flight- and got ! pressure as wiU, the Magnan and Harth gliders. -This was un- · the remainder from some then-uruecognized form of lit in the questionably a serious weakness. The fuselage was squat and THE AUTHOR, who alternately finds himself either a century area. Be that 88 it may, Harth demonstrated dynamic ooaring on birdlike. The pointed nose was covered with a transparent ahead of the times, or a centiiry behind, has listed among his UiiB and other occasions in 8 most dramatic way: he launched material, poBBibly mica, which givea. rise to Uie auspicion that Future Projects Number 719 (W), or GRANDIOSE SCHEME FOR THE himself completely independently by waiting on an upolope, the pilot was to have aBSumed a prone position during flight. The CASUAL CIRCUMNAVIGATION OF THE GREAT TERRFSTIAL SPHERE facing the wind, and using an opportune gust to literally; tail was a flat, splayed V similar to that of birds such as the WITHOUT MECHANICAL MEANS AND AvomrNc CusroMs -an obvihike himself into the air by his bootstraps. · pigeon. The control• were completely enclosed in the fuselage, a ous extrapolation of the work or Wolf muller. However in this Harth,_ 88 n..y reaeonably be expected, had sacrificed much very unusual refinement for the day. hot-paced age, when speed and expediency are valued above all to the lightness of his gliders. His Heidelstein machine had just , It is hardly surprising that a machine so far ahead of its other qualities, 719/Wl seems doomed to failure; so the author, to , ---over sq.f[ofwing ltlie equivalent- of' the 'Schweizer-·:-time ·and incorporating SO many radical inhovati01,s-was-n-oi-suc~--save-himself-undue-/rustration;shiflinhe whole matrer-itito-1an- · _1-26 and the Vampyr) and weighed in at just a bit over 100 I cessfully flown. Ing. Wollmuller, however, did fly some heaviertaey and turns the clock back ... )bs. tpe resulting fragility, coupled with the extraordinary exer-. 'than-air dynamic soai-ing craft and, providin_!l the Chinese or It is fin de siecle, the tail end of the age that brought the I'

I_ ·1

necessary

rso·

area

see J.18

3, 17

THE END{of a non-dynamic soaring world) WE thank Richard Miller once again for letting us be sure of recording his rusts m our--fantasy:-Jules-Verne,------Tom-Swift and- Horatio--Al-•- - mor!":J1g,_~~ne three--im~ible--th.ings.-_before-~-:~~st~-classic article on "Dynamic Soaring" in gerstein-are an amalgam of the most fortuitous talents of the I age and a trinity whose individual contributions of imagination, im-i its proper place:l.&S, TO FOLLOW is.an appropriate expression from our new members plementation and impertinence culminate in an undertaking of I Steve and Marilyn Riskin who operate a moat successful "peripatetic" school in Los such enormityi one so daring, yet devoid of reaJ risk, one so Angeles, I..&S in every way wants to encourage its members to really be free in their presumptuous, yet plausible, that it strikes the common end un. common mind alike with its stunning, galvanic force. intellectual and practical investigations in the realms of free flight, Miller's From the English industrial heartland coine powerful wind-, article led us to seek a solution through excitement, belief, play, and enjoyment lasses and miles of fine steel cable; from the Zeppelin factories of possibilities, Let us listen for a moment to our peripatetic friends: "OUR EXworld the steam engine, the electric light, the engine-powered

dir-1 adventurers converse on irrational numbers and imcomrneri.sur..;

i~ible,. wireless and railroads that span continents. The protago-

on the Continent, great girders and trusses; from Japan immense bol~.!!f_ buff silk; from America ,the l_~~t ill lj_gh_ting eguipment. '. The inventors, at work in huge sheds on the Atlantic seacoast, · labor through the winter in shrouded secrecy. In the first warm days of spring mighty sections of framework are transported to a near-by beach where they are bolted together. As the silk cover- I ing is applied the shapes of two incredibly• large airfoils, each 1 with a chord of several hundred feet and a span of hall a mile, emerge.

· By autwnn the aerial giant is complete and preparation., for : launcrung are made. The first of the two airfoils is kited to an altitude of several thousand feet using ponderous concrete blocks as anchors. Next the lower airfoil, all properly rigged, is made ready. As the day designated for the launching arrives great crowds gather to watch those who are to make the trip mount the motorized bosun's chair that climbs, time and again, the slender

wire that_ disappears, through occasional puffs of cloud, in the

direction of the wing waiting high overhead. Finally the last preparations are made. A green flare, the signal to begin, arcs down . through the sky. Stout men, on command, raise their axes and , with concerted cuts sever the hausers that hold the great engine : tied to Earth ... Effortlessly the unfettered machine slips into the air, falters ' just a moment, then takes its hmding down the· wind. Miles aboYt! the earth, isolate in the spacious glass cabin ·at the center of ,the upper wing, the passengers watch the coast re,:ec!e and feel themselves borne ever higher on the buoyant breezes. From the control room. with its banks of switches and levers, its rows of dimly lit dials, its compasses and charts, go the commands that cause the windlasses to churn that steer the behemoth along the vastest ocean of the world. As daylight fades the red and blue navigation lights flicker ncros.s the gray expanses oC fabric. The stars tremble into exist-

ence, and on the win~s meander through the cx,eanic twilight. Snug within lheir cabins, hearts rounded with hope, the aerial

able quantities and, providing they get up early enough in the

perience has led us to expect that once the" chiidren can.grasp certain pheno: mena as problematic alJnost nothing can stop them from searching out various solutions, We have also found that those 'solutions' are often absurd, spectacular, highly creative, innovative and indicative of a sort of 'logic' that is often very surprising, Thus we want first of all to get our students to be unafraid to express their unorthodox and untaught solutions; we want to validate and praise as many attempts at solutions as possible; we want to try to understand what it is the child is trying to do, We feel that children alJnost never make mistakes; that they are alJnost always trying to do something; and that they need, more than to be set right and corrected, to be shown how to do what it is that they want to do, We want to use praise and validation as a primary instrument of teaching. We want to be flexible enough to follow out their attempts at solutions, showing how those solutions solve the problem, solve part of the problem, raise other unexpected consequences, can be modified to include more of the problem, are similar to solutions offered in the history of science and sketch out something of their conceptual and intellectual ramifications, show some of the conceptual costs of such solutions - in short, praise, validate, and educate by a flexible sort of conceptual dialogue, experimental where possible, that can serve to give the child the sense that, however absurd his solutions might seem in 'normal' frameworks, they are pel"fectly reasonable and reasonably connected to a whole panoply of other considerations, We want our teaching to be an extension of the child's own reasoning process. We hope that this will build a confidence that is usually lost in situations where the child is educated by constant correction. We hope that it will provide the child with a sense of the flexibility possible in forms of analysis, Above all, that it will eerve to keep his interest in what is after 11 all an enormously interesting world.

\.Al

u•.,~

Matt Colver and Ernest are two teenagers that meeting resistance in Mesa. Your ED sees these two as leaders in the on-coming I.&S type sports and hqbbies that will be found happening in parks one day. Balls and kites fly now, one jumps, skips, and runs like a bat .out of Hadea;very dangerous sports like football, soccer, hardball, pole-vaulting and such are more 11:ely · to be limb breakers than a little ground skimming. Matt and Ernest built a fine Rogallo and had some short hops They used bamboo and polyeth elene. Presently Feher is putting the final touches on an aileron system for the ah ip pictured. See l.&S 4. They are beginning a biplane H-G. 1.Q:Q.:"Nearing completion of putting it together for the first time (in Twinkle Park) which took about an hour and a half." Mid&Bot: "Test running it on level ground and getting tha feeling of getting your feet off the ground. On BOT, you can see the beginning of.the hill we flew on later and next few days until we got kicked out." Ernest: "Later in the year I might write an article about our flying in the park and the City Park and Recreation people making a law against our flying on park property." ED: Hold a kite contest a· the park and let your kite lift you a little bit more than the other kites lift others. And if anyone does not believe that the kite is a kite, then simply wear a long shoe lace that hangs to the ground while your kite lifts you along the slope breeze! ********WE encourage mature dialogue with all authorities, but the unfounded fear of some flying machines might be hard to move aside in some communities. Birds should not be the only occupants of a park's air. Man is coming ••••• prepare.

3.19