LOW & SLOW 6
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6,2
A message
to the President
Letter to the President of the United States of America from Low & Slow: Low & Slow 59 Dudley Ave. Venice, CA 90291
July 20, 1971
Dear President Nixon, Your personal award in 1960 to me at the California Pre-Olympic Meet in your home town has been treasured. You signed the "Athlete of the Meet" award for my manpowered flight high jump of 6' 1 H 11 • From those efforts and in combination with my desire to lift the hearts of families, I am publishing Low & Slow. Mr. President, Low & Slow informally promotes low-cost, fuel-less flight systems ranging from master kiting to hang-gliding. Done with judgement,as in sailing and surfing, safe and beneficial enjoyments and lessons can be had by those of light heart and soundi!:lg mind. Wishing you good airs, ~
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Joe Faust Editor, Low & Slow Sir, if you wish, you may continue to receive issues of Low & Slow without subscription. Please tell me if you so wish. Your interested friends are welcome to subscribe to Low & Slow at $6 for 12 issues.
Enclosures: Our first five issues of Low & Slow
********* Please read L&S 5.2 for key points of organizational policy. Thank you, Copyright~ 1971, Joe Faust eovers by George Congdon of California **«*~*********************************
All rights reserved
LIFE AND HARD TIMES IN THE AERIAL UNDERGROUND by Aasvogel'" Those who attended the triumphant Otto Lilienthal Geburtstag on May 23, courageously mounted in the depths of Orange County, were treated to a rare spectacle of masochism and ingenuity. The initial response of Orange Countyi tes to the invasion of the hairy birdmen ( undoubtedly ,·,inL, to boot) was on the inhospitable side. The gendarmerie was summoned, ancJ arrived with despatch, both by land and air. Happily after calming wor(b from fearless leader Lambie, the forces of law and order assessed the swelling multitude as palpably insane, and as impotent a threat to privato property and godliness as they were to the kingdom of the air. The great Otto Lilienthal low and slow debacle was permitted to follJw its own course of self-destruction. And destruct they surely did.
Before the sun set over the gleaming Pacific,
many a noble structure had bit the dust and many an aspiring aeronaut was regretting his excess avoirdupois. "Oh, that t!iis all too solid flesh would melt." Many dreamships faced the hard facts of terra firma and many an ins1,ir-ed desi1;ner learnt t!Jat although (as accused by their unwilling hosts) one might flaunt the laws of God and man, the laws of Physics are mcide of sterner stuff. To (fate they have resolutely resitit.ed all attempts at repeal This is not to state that there were not bold and daring flj.ghts - in particular the gentleman manning the Black Rogallo gave an outstanding exhibition of skill and elan. Much there wa.s to reflect upon. Let us trust that it js learnt, marked and inwardly digested. Meanwhile, in the crowd of houlevardiers, femmes-du-monde, jongleurs and voyeurs, there was a nucleus of professional aerotypes; viewing the scene with hard eyed reason, learning by our mistakes, planninc; ,rnd plotting a.gainst the inexorable laws of Newton Bernoulli and J oukowski. Vie lwpe that we may hear from them. Meanwhile, in a spirit of cheerful amateurism, your scribe pens a few of his own feeble views on another aspect of the RAF mot to, Per Ardua ad Astra ( oy labor to the heavens) or why it's hard for men to fly. There are really two basic problems - people are fat and brittle and air is thin and lumpy. Let us consider these unfortunate frailties of humanity first, If you can do the 100 meters in 10 seconds you should not be lumbering up and down California. hillsides, you should be doing your flying co,1 ,... tesy of the Boeing Airplane Company enroute to the Munich Olympics. Anyl,-iw. you can't make it on foot at more than 20 mph - and if you' re a four mj n1., ,.. e miler your average running speed is only 15 mph. Again, try jumping off successively higher ridges with a 40 lb. backpack, you'll find that at about 6 ft. the fun starts to wear a little thin. Finally, keep the pa.ck on and project yourself from the tailgate of a station wagon travelling a.t 10 mph. When you've got the hang of this, you're ready for hang glidine;. Most See 6.17 * Aasvogel (carrion vulture) is the nom-de-plume of a well known aerodynamicist and sex researcher who will be an irregular columni.st.
6.4
Confidential Preliminary Information
The cape that makes you feel superhuman or 'tis wise to listen to the summary of the ages. We welcome Vic Saudek 1 s letter to the editor of Soaring, the journal of Soaring Society_ of .America. See reprint below:
The Nader Principle in Hang Gliding Dear Sir: Otto Lilienthal made more than a thousand flights, hanging from his calloused armpits. He used a number of winged contraptions, the ribs of which might better have afforded many shady hours of fishing to a number of people -simultaneously. In effect, he lived eons before CAB Accident Boards ( though people who saw him alive are living still). Now, as Jack Lambie so nicely put it ( Soaring, July), "Everything has been done in gliding . . ." But it's exciting to "start again," and walking on air with curly beards and locks flowing in the breeze is the most "in" sport since 1891. Nostalgia lives and breathes ... I quote from the good Otto ( from memory, of course): "I was saved from further hurt by the structure forward of my body/' This was caught by the Wrights, so they located the elevators ahead of them. To further emphasize the 20th century's start, thev coordinated their wing warping and att rudders. And with that, deliberate aerodynamic controls were proved to be the critical advance on heavier-than-air flight. This need was made._.obvious by Lilienthal's death from a gust-induced staII and fall which cannot be countered by any amount of frantic leg waving. Three lessons of 75 years ago are clear: I. Crunchy energy absorbers ahead of one's vital organs, carefully designed to prevent stress upon the ribcage and to deflect puncture-prone pieces of structure, are essential safety features in design. 2. An escape route to the rear, so that the pilot can avoid whiplash and other impacts from abaft. 3. A bow to the control system of Orville & Wilbur, who provided at least some mastery of unpredictable i,nsts.
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Saudek's "Hang It" The price of sensible design features is no small thing. Probably Otto· would gladly have given up his wild and inept gyrations for something like stability and control, if only to have avoided the broken back that killed him. He lacked knowledge, for he was an explorer of unknowns. We do not have that handy excuse, consequently, we expose ourselves needlessly "to experience how it was in Victorian flying circles."
See 6.6 bottom
WALKING THE PLANK
: FLIGHT TO NEVER LAND
Pictur·ed abo·.;e is the wing-rib jig and rib work station in Dr. Bruce Carmictael's garage. His w!ng-r·i0s weigh 2 oz.each! The parallel hangbar,, are shown to the left. The 63 (10)-12 airfoil lines can be estirr.ated from the picture while reviewing the wing and rib data Bruce gave u,; on L&S 2. 12. Combine this with the incomplete drawings soon to show i11 L&S, add your 011n ingenuity and delights, and come up with possibly a good 'skimmer', maybe 'soarer.' Who will know until such is tested? With highest regards for the competence of aerodynamicist Dr. Bruce Carmichael, L&S extends to him an invitation to use L&S for his vehicle of recreative mind soaring. However, we feel that recreative involvement is the garden of inspiration that is most likely to produce scientific and practical breakthroughs."(see end for US index on Bruce) We bave Bruce to thank for nurturing the beginninr,s of Low & Slow. His corr.panionship with Richard Miller has founded many airways. Bruce's soaring, man-powered flight, and hang-gliding interests remind us of why he is chairman of the SSA aerodynamic committee. His skill does not end with the theoretical, for on May 23, 1971, for Otto,he had one of the three best foot-launched flights of the day. Bruce's hands and mind delicately feel the flow of air; his peaceful home appreciates the Spirit. His wood bird,wing,and sailplane carvings please touch and sight.Computers whine at sensing the airfoil sketchings that come naturally to him. * Trying to muse parallel with Bruce: What is left in air to do fuellessly? Ans.:L&S: Man-powered sport and practical systems; everyperson's near-home low cost mobile soarer;and a full appreciation of the artistic mind-soaring play that promises to give an outlet for undreamed breakthroughs. But tl,ere are rumors that 'all in gliding lras been done before.' Even some top leaders in the soaring society believe this.Not all.Lambie has voiced this also,even if he did not mean it. Had the Wright Brothers believed such, aviation would not be where it is today. Had Einstein believed classical physics expressed the universe well enough, we would be without his relativity.Much has been done with a couple of wings and •••• variations of a theme, but NOT ALL HAS BEEN DONE. WE ARE NOT MERELY STARTING OVER AGAIN. Those who rest comfortably as though all has been done will eventually be left behind - maybe not this year but in years to come. They will form the old school of thought while a new modern school advances the frontiers of fuel-less flight in the low and slow regions. Morphologically the history of model and practical aviation 'II·
v,v
development has shown that such was distorted for having to meet the needs of war industry city ways and transportation. L&S intenrts to be an organ for the de~elopment of fuel-less·flight,not for war or speed or escape or even for necessary recreation,but for reverence of the good of undiscovered possibilities useable b~ many interest groups and enjoyed by the peaceful little guy in all the nooks and corners of the world. Bruce reported in past issues on his building of a finely designed controllable high performance 'hang-glider.' See past L&S, Bruce has provided us with three view incomplete drawings to be published soon. In April,1971, Bruce was working diligently on his ship. In June he had to "get back to work on my 45-lb. 'sailplane'". Quotes on 'sailplane' added by ED. By such evolution from "hang-glider" to "sailplane", we may end hearing that Bruce has been advancing on his ideas so rapidly that finishing his fjrst ship might seem a waste of his garage time. We only hope that Bruce continues to enjoy the challenges of ultra-light flight. (***Flash: From Bruce: "I am building a 1/10th scale model of my Rube Goldberg idea for a cloth plank. I don't expect it to work but will take the Miller approach to prove to myself why not. It has a deep triangular c.enter truss the bottom bars of which support the aeronaut and also anchor the brace wires for two spanwj_se lobes. There are reflexed ribs every so often but no spanwise stiffeners. I expect the lobes will collapse to semicircles and run the span loading to hell and gone, but it will be fun trying it out." ......... When and if Bruce decides his course, we would be very much intere3ted in knowing reasons. From Dr. Carmichael in our next L&S booklet we will have a simole-to use estimating chart for cl.eterminingDying speed when one's wing's lift coefficient is known along with gross weight and wing area. Knowing the expected flying speed one can quickly estimate gronnd speed for feetle operations during take-offs and landings occurring at flying speed, We can use the chart to estimate the lift coefficient of an experiment~l wing if we have a reliable estimate of the wind speeds at which variou~ things happen,like stall. Feetle speed will be flying speed minus the wind speed facing. THANK YOU, BRUCE.
~L&s index on Dr. Bruce Carmichael:1.11, 1,19. 2,10, 2.1z, 2.15, 3.5, 3,7, ••*********3.15, 4,5, 4.6, 4,10, 5.3, 5,13, 5.14, 5,16, 5,17, and here. *************************************************************** cont'd by Vic Saudek from page 6,4: each hand) pitch, roll, and yaw conThe law of survival of the fittest is still trol ( with help by pilot shifting his enforced by the implacable order of weight); to provide pitch and ya"· natural events. The men who crossed the stabilizers. poles and walked on the moon did so onlv c) Reasonably cambered airfoil with two by using every advantage available. Thu;. to three-degree washout on both sets, if one must take a long, running, gliding and some lower-wing dihedral. jump down a grassy slope, let it be in d ) Reasonably simple low-drag strucsomething thoughtfully considered, so ture, taking into account low Reynolds that surviv ,l is less than accidental. number and ease of construction. Many varying concepts will no doubt Wings must be made unusually rigid emerge, but-for a starter-here is one in torsion and extremely light. that attempts to embody at least the three It is not recommended that one flv above 75-year old lessons, and some of ahove ground effect altitude ( i.e., n;t Mr. Ralph Nader's philosophies: a hove six feet) for reasons of reduced a) Swept lower wing: to put loaded e.g. aspect ratio effectiveness and kinetic in proper location; to put spar, rib~, energy. The two-surface .tails will provide and deep coaming ahead of pilot; to three-axt•s t·ontrol, hut are not sized to keep wingtips from digging in; and to do away entirely with the need for the permit the ship to be stable resting pilot to squeak fore-and-aft for better on the ground. pitch control and thus permit more body English for roll and yaw. b) Spaced, inverted vee-tail: to reduce A steady breeze of 10 mph will make number of surfaces; to remove struca delightful challenge for youngsters ( 15 ture from behind the pilot entirely; to mph if above 40 years old). Windier provide ( by using a control stick in days may encourage the pilot to add s~e 6.18
INNOVATION
6.7
Soaring pilots who had just paid a good sum of money to have a big fueled device tow them to the skies viewed a modern Icarus. ·foot launch his way to long duration flights in our insubstantial air. The cloud cover prevented these new wings from melting. See 6.10-11 photos. Meet Dave Kilbourne as he takes an afternoon respite from the toils of earning a living and supporting his own frame. ".And we're very curious to know more about the Mission Peak pilots, male and female, and their long flights," -Richard Miller. Had each of us been following the professional car and boat kiting exhibition scene we 1 d know Dave and his friend Donnita Holland. However, since Dave seems to be tackling self-launch fuel-les8 flight systems problems, we concurrently find him willing to share a good deal more thoughts with us. Let Dave tell us: "Here's some pictures of the San Jose area where I fly sometimes. The wing is 16 feet on the keel, 400 on the wing angle with 440 on the sail cloth which is 4 oz. dacron. The harness is a plastic toy swing seat with auto seat belt to hold it in place while running. All control is with weight movement which i s ~ sensitive. Slow flight is about 10 mph with a stall coming on very gently; fast flight is approximately 35 mph. Glide ratio is 5 to 1; sink rate 500 f.p.m • . SEE PJ..Rtu-DRAWtNG- ATTIKHMENT I've made approximately 1,000 safe flights, the highest at 2,500 'AGL, the longest 25 minutes ridge soaring on Mission Ridge, Fremont, CA." " ~ The Bamboo Butterfly,renamed the Bat Glider (23' keel, 16 ft.aquare,
JV"~e wing angle as Kilbourne wing) (See L&S 3.19; 4.11;4.13;4.19;5.1;5.20; 2.3;2.2;1.10), does not have the simple control bar and swing seat that is used on Dave's wing. The hold bar has two ends. From each end are three wires: One wire is attached to nose, one to intersection of cross-spar with leading edge spar, and one to the back part of the keel boom. When such is done to both ends of the control bar, the bar is held rigidly in space relative to the wing. The pilot can push himself or herself away from or to either side of the bar as needed for obtaining control. The swing seat permits the pilot to operate on the ground even though being strapped in with a safety belt; there is no armpit discomfort. The $10 cost of a workable Rogallo using a piece of 16 1 x 16 1 polyethelene plastic is a far cry from the cost of 2 or 4 oz. dacron. Airspeeds for the larger Bat Dave further tells us: Glider are less than Dave's wing. "I'm sorry I missed the championships, although my roggolo might have had a hard time taking off due to the shallow angle of the hill. I have mixed feelings about helping anyone duplicate my wing or my exploits!" We missed you, Dave. At the meet we had a Scott Strom with a wing that was just your size but a bit lighter. Breeze, wing loading, and slope were against him. However, the larger and slower ships did make some foot launch flights. L&S would not recommend your altitude experiences to anyone not having his ship and training checked out by experienced and knowledgeable Dave continues: pilot-engineers. "You see, I learned very throughly my machines and my piloting technique by being towed by a speedboat, so my crashes had the advantage of soft water to cushion my impact and ~ impacts I've had too! I flew hundred~ Jf times for almost a full year 'h"-P ........... o .... ++om'l"l+iYlD" f1vil1JJ' nvP.r l::i.nd .. "
6.8 Dave, as water· soft at 35 mph? . adding the falling vector? ••• plus having to know how to breathe under water during an emergency! And while you were beginning you also had to learn to coordinate with the fueled boat crew. Having a ground speed of 12 mph at an altitude of 10 1 over sand or grass combined with a larger canopy that is not too bad of a parachute in a stall is the pattern of first flights for thousands of Rogallo wingers. They do not have to learn the coordination of power-boat tow nor have to swim or ski. The walking on land is easier than walking on water. Dave, if you intend on competing with the fellow that will be towed to 5000' this summer behind a fueled power-tow, water is an excellent place to be. We all probably agree that water is softer than land. But Dave, we sure would like you to describe,as carefully as you can, the events leading to various kinds of impacts. But for now Dave goes on with his welcome story: ''The kites I flew first were designed by Bill Bennett and built by me. I have to thank him for getting me started right, although more for construction and design than for piloting. He sort of let me take my own crashes." Unfortunately, we hear that Bill took one of his own crashes. See this issue "Safety Service #2. Bill's wing sells for almost as many hundreds of dollars as fingers on one hand •••• enough to make 43 Bamboo Butterflies. However, a quick bamboo ship should not ever be stressed as though it were fully tested for just any kind of flying. (note: 'keel-beam' added by ED.) "The 16 foot(keel-beam)wing I fly now is my own design having proved my own theories of sailwing flight by trial & error ---Love that water for errors. Bennett was aware of my design before it was completed and told . me in no uncertain terms that it was all wrong, but proof is in the performance, and perform it didl -better than anything he had ever seen, •••.•• " The design was intended to reduce sink and extend glide compared to the water-ski version so as to make ridge soaring possible. Despite my 25 minute flight, I consider it a failure in this matter. The wind was blowing a full 30 miles per hour when this feat was accomplished. So you see, the flight was more a feat of daring than actual aerodynamic accomplishment." I have been hoping Bill has some amateur spirit for himself that might permit him to enjoy participating in Low & Slow. Having his livelihood depend on sales of kites might not leave him with the feeling that he can afford time for too many modifications of his flight systems. Bill wrote to me and said he~d "love to participate." He generously sent copies of his delta-wing products as per my request. Hope he contributes some technical and green-back notes to L&S ••••• because L&S operations will provide the world with & continued development of interesting systems utilizing advanced modifications of the Rogallo families of wings. We surely empathetically appreciate your enjoyment, Dave, in designing and building your own wing •••• and further testing and evaluating the same. History has left for low and slowers a concrete chance to obtain original practical aircraft ideas under the operations of just a couple of workers,if not one. Dave, you were daring and did achieve an aerodynamic success, although, happily you are dissatisfied and thus we vibe with you and hope for you to have an ever keener insight into the alluring mysteries of self-launch flying. WHEN IS A HANG GLIDER A SAILPLANE? Anyone? Dave continues:
"My goal is a truly portable wing (which I now have) with good sink rate and adequate penetration (which I now don't have). Hieher aspect ratio is the way to go (I know the stability problem -"crash", love that water). I have some original ideas (I think) that will solve the stability problems." Its been the parallel hope of many to widen the wing angle of the Rogallo type. Aasvogel counsels to spend time on airfoils. Dave wants to stay portable now that he has that quality. NASA spent millions to visualize the trade-off with stability for higher aspect ratio on these three-boom sailwings. Miller's XFSW-1 (L&S 5.10-19) might just be where Dave is headed, except Miller brought his wing to the meet in a trailer •••• however, such does not have to be the case .••• and Miller speaks of soarability in very clear intimations (L&S 5.19 bottom). I see Aasvogel and Carmichael getting a brainstorm effectively incorporating an excellent airfoil into the portability of Kilbourne and in the ingenuity of Miller. If that doesn't soon produce a SSA qualifier, then maybe Cahn and Privett will launch and pump their way to a modified solution of sustaining. Anyway, Dave, do not take so many crashes .••• its beginning to tire the old bones .••• Dave; "I'm looking forward to half a dozen or more sailwings chasing the gulls along the cliffs of anywhere California coming down only when the wind dies or when i~s time for dinner. Many of us know this is possible, so let's get it .2_~! Could be the greatest thing since surfing!" Dave, already others are doing minor ridge soaring with major enthusiasm and without getting higher than they would be willing to fall. But the air wave skimming is still advancing on the delights of surfing. "The gal's name is Donnita Holland who is without a doubt the wor~d's gre~tes~ roggolo wing pilot. She is my constant companion•and inspiration. She drives when we tow, she carries when we hike, she is the one who took the pictures on Mission Ridge. She has flown many times on tow to over 1,000' A.G.L. She is the one and only woman to drop from a hot air balloon lift, approx.1,500 1 AGL. -and you already know of her other great Mission Ridge flight. -Keep em' flying, - •••••••••••••••••• F .A.A. -Keep Low & Slow coming & ~Peace on earth & Let the little guy fly. 11 Dave Kilbourne
....... • .... a.Je91A.a..1:le c.on'tro
See plan talk on page 7 Use this picture plan also for aids,
6.10
Detail plan drawings are on an attachment to this booklet. Use them with the picture plan below and talk on p. 7.
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6.12
SAILING ALONG IN E~
MAJOR
or "Where did you go? nout!"
What did you do?" "Played Beethoven's 5th on my hang glider." 11
by Richard Miller ~ n accurate airspeed indicator for a modern sailplane is, by low and slow standards, a complex and expensive affair. Even the plumbing necessary to work one - a tail-mounted, low-velocity, total-energy venturi - costs about as much as it does to build a hang glider, at least one of the shaggier variety. Instruments designed to give reliable readings at very low airspeeds are relatively more expensive. A further disadvantage of these instruments is that they rely on the archaic method of visual presentation of data which demands a) reference, b) interpretation, and c) response, instead of the more direct method of audio presentation which gives a direct and continuous flow of information which we can monitor almost subconsciously and react to almost instantaneously. Compare, for example, your response to 14 and ~IV. In the first case you know immediately exactly what is meant; in I the secjond you are forced to pause and deliberate. Thie pilots of ·conventional gliders c:i.n, of course, afford the instruments ttey use. They've got scads of mon:y and plenty of time between turnpoints at t2,000 ft. to look around at clouds, take a drink of water or talk 1 to their crew on the radio. The hang-glider pilot, however, is much too preI occupi~d with the very immediate business of staying up to have even a second I or two Ito spare for anything as wasteful as reading an instrument dial and figuri~g out what the information on it means. He requires a more direct system,' some simple little black box that he can install in a moment and which is, moreover, durable, reliable, light, and inexpensive. c1nsider, then, the Synchrotone pitch pipe, o~ which I happen to possess an example. Mine is a number S-6, used for tuning a cello, and cost 90 cents, plus applicable state and local taxes. It consists of four small tubes, an alternate pair facing east, another alternate pair facing west, their bodies partially overlapping, and measures, overall, 7/16 11 x 1f" x 2". It weighs half an ounce, give or take a gram or two, and is the same color, with the same options, as Henry's Model T. Available from your neighborhood music store or the Wm. Kratt Co. of Union, New Jersey.
The pipes sound by means of reeds within the tubes which are activated by air passing over them. The notes on the cello pipe naturally correspond to the strings on that instrument and are consequently tuned to intervals of a perfect fifth. Thus any combination of notes sounded simultaneously will tend to have a pleasant sound.
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Furthermore, the cello (CG DA), the viola
( CG DA an octave higher) and the violin (GD A E) have most of their notes in common (see chart) so that pipes intended for different instruments can be combined with sonorous results.
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Violin Everything about S-6 suggested that Viola it would make an ideal audio airspeed inCello dicator, or an element in one, provided only that its range of operation coincided with hang-glider speeds. Some simple tests in an open car, with the pipes strapped to a short length of yardstick,,settled the m~tter. No particular care was taken to determine the exact ~hreshold and range of the various notes on the pipe because it was immedia~ely apparent that they fell exactly in the desired range. Moreover, each pilot . I will have his own requirements and will find which notes on which pipe~ best suit his needs by trial and error. Suffice it to say that the low-notJ (CG) side of the pipe sounded at about 16 mph and increased to its maximum volume, with no change in pitch, by about 25 mph. Beyond this there appeared ~o be no change in either pitch or volume,ap to freeway speeds. The two higher notes began sounding at a slightly higher speed and took relatively longer to reach maximum volume. Pitch and volume then remained constant up to the 60-70 mph range. The total range of volume of the pipes is not great. At a distance of 3 or 4 feet from the ear they can be heard distinctly from low through high, but the sound never exceeds a reasonable upper limit. The two higher notes, D and A, seemed preferable to the lower pair. Not only did they seem to be more in the hang-glider range of speeds, but they also sounded with greater clarity and it seemed easier to distinguish changes in volume with them than with the pair C and G. Having the pipe on a length of yardstick, incidentally, not only helped in lining up the instrument on the relative wind, but permitted yawing the stick through 20 or 250 of angle which showed that the pipes were not critical as regards intake direction. If you intend to skid or slip at greater angles than that, you can mount your airspeed indicator on a small weathervane, then at least some part of the glider will be lined up with the airflow during flight. ****************
Once you have the pitch pipe in hand, and realize what a neat little item it is, there is no trouble in rearing back and devising half a doz~n instrumentation systems using it as the basic element. The simplest in~ stallation, obviously, is to find a pipe that brackets the airspeed of your glider, or comes close, and to attach it to the nearest handy strut. There ! are, however, artsier and craftsier systems for the ambitious.
6.14
For example: Start with the airspeed of the glider, which we'll assume to be 20 mph. Add 10 percent to this - 22 mph - and use this as your base speed. Next, firid a reed that begins to vibrate at that speed, or as close to it as possible. This will be, to keep to musical parlance, the tonic note of the glider. When it· sounds, provided you 1 re not skidding or slipping, you have assurance of flying speed. Let us, then, mount chis first reed to the pilot's right and within easy hearing distance. On the opposite side we will put a second pipe tuned to vibrate at, say, 28 mph. We then operate as follows: On the run down the hill the pilot maintains his take-off angle-of-attack and continues to gain speed until he hears the sound of the tonic note. Only then does he rotate into a normal flying attitude. Thereafter he makes every reasonable effort to keep the note sounding by maintaining proper airspeed, and should it stop, he knows he is headed for trouble. Should airspeed build up for any reason, the volume of the tonic will increase until, at a certain velocity, it will be joined by the new note the dominant. This note can be used in a number of ways. Perhaps the most appropriate during the early stages of the sport would be as a kind of turn (permission) indicator, that is, a note to indicate the safe forward speed necessary for a normal turn with, say, 30 degrees of bank. Holding adequate airspeed in turns, not to mention in level flight, is going to continue to be perhaps the most serious problem hang-glider pilots face for a long time to come. Consequently any method used to insure the maintenance of proper flying speed is worth consideration. One could even go to the extreme, Lancaster in one hand and Helmholtz in the other, of calculating and cutting reeds designed to indicate a safe speed for the inner wing-tip in turning flight. Such a project is not difficult. It just takes a peculiar type of person to do it. Somebody like - ummn - Well, you know, old what's his name. Another problem in turning flight is proper coordination of controls. In the case of the hang glider it is complicated by (at least) three factors: 1) The pilot's position is such that he generally has no forward fuselage on which to sight in order to judge the attitude of his craft in flight. 2) There is no convenient forward structure on which to mount a yaw string and any such mounting, directly in front of the face, would be a hazard in the event of a crash.
3) Ir."'"""' ~ienr So why not an audio device? 0
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Weathervane~held pitch pipe
Fin -.,. Hinge point
ir-.
Pitch pipe
The drawing shows how it might be done. and a noise-maker beneath.
The ·ane carries a fin on top
It pivots on the vertical rod attached to wing
or other structure. This rod also carries a light beam running under the vane at the end of which is fastened a curved plate. In coordinated flight the noise-maker is masked by the plate, but in a slip or skid it rotates beyond the edge of the plate and begins to sound. A visit to a music store, a toy ship or the five-and-dime will reveal the existence of all sorts of tuning devices and noise-makers that can be used in an audio system. F ,rhaps nothing else in flight is so important as the maintenance of adequate flyiag speed at all times. Consequently any device that keeps us infor~~d of our airspeed, particularly one as simple and inexpensive as a pitch pipe, deserves consideration. Matt Colver features his visit to the International Flight and Space Museum at Orange County Airport by sharing with us these photographs of replica hang-gliders. Right is a Mon~gomery Tandem Monoplane. The pilot would straddle the lower beam. Popular Mec:1ani~ has publid,ed plans for constructing this hang-glider. Matt Co.lver and Ernest Feher, featured on l.&S 3.19 are now building a Montgomery with a longer wing span than the original. (L&S 2.3-4) Below are two shots of a replica Chanute Biplane (ref. L&S 2.4). Notice the position of the parallel hang bars and compare with the same in photograph on the back cover of L&S 5, right second from bottom.
Be
(This section will be a regular L&S l'ooklet section prov::di.::c 02 wit:· ar: opportunity to investigate the me: eorology and aerodyna:n:;.cs cec·.:lia:?.' to low and slow fligl;t sy2tems. 1 "FROM DUST THOU ART and TO DiJST THOU SEALT RETURN''--------T',e:·:raL, lj.f't moisture wtile the ever ~resent dust particles pro~ide the Roo,i ea:·~;1 wit.r, an efficient means for bringing water particles b"'ck to nou:·::.si, li--ing tnings. In a household,dust is defined as :natter Jis~l~ceJ; but in our larger household -our airspace- just is more wonderfully aprre~iated as that realm of matter iH-small-size-enough to fly Rhout to Jo mRny wonderful things from amazing a child of its an<_.ics of fligr,t .in ,, ,,trea,, of sunlight to its fertilizing the gro:.:nds for c:·ops. Alt'·,ough ·:List ,;-ay be a flight vehicle of high wing loadin6 , its size ,crr,,.:.ts air rr.olecules ( oxygen or nitrogen mainly) to hit those wings :~a::-d eno;; gh to keer it sustained for quite awhile. Dust will settle wt.er, it stops s;1,;tai:;ing by virtue of the pressures exerted by rapidly :r,o·:ing ai!' :;;olecules. Heavier-than-air dust particles are s,;stai~1ed in air ·:ia several processes. Above is introduced the method of gust sor,ring: tl:e dust often just does not fall faster than it is pushed up by t!-.e ll'Ost minute gusts. While being battered around by tr,e smallest of aL· gusts ,many dust specks meet rising currents cf warmer air only to take a ride to a higl.er altitude. Some specks rise faster than ot!",er.~; some vi\nate and rotate. No speck falls wi~hout interference wit~ air molecules. Let's make a dust-ship c.nd sustain! very fine. Lay a netting where
Let's see: Take fine fiber---
fibers are separated by 10 fiber diameters
from cne another in a grid pattern.
Drop thousanas of heJ~x shroud lines
to a harness anci wait for the slighte~t of thermals to drift you away. Some plants have worked out this construction quite "ell. Tiieir seed pods have a big bundle of fine fibers sticking out away from e;,.ch other. A gust of air at the right time of year puts the seed on a low end slow journey through the air --no fuel nor lighter-than-a:i.r ga.ses involved. Some seeds will settle nearby, other far from the parent i:,lant. Some pilots in l.&S are already intent on throwing out their fiber bundles to take a ride with the wind---adjusting their bundle shapes to best take advantage of the changeable air.
Otr.ers are intent on going
against wind with penetration in order to meet gusts sooner and more frequEntly perhaps.in order to use ti,e gusts to sustaining advantage in a si"iorter period of time.
Sucb penetration is obtained by running, falling,
fuel-less towing, or by reaction to man-powered in-flight devices.
Sustain-
ing can be achieved with the wind or against the wind. Traveling the same speed and direction of the general wind requires a flight system that is akin to the dust ship if one hopes to sustain. When penetration and highly effective ship snape are combined in one flight system, man has found that he can travel fairly fast and far without using fuel. When penetration is not so much desired, effective ship shapes ~~"' o+; 11 hP. ilP.vi sP.d for enduring sustaining.
Let's find those shapes.~
6 .17
(cont'd from page six point thre~) _ aficionados of our noble.sport, t~e sport of kinks, could not be described as in the peak of training. In their Sybaritic lives, given over to wine, women and song (and all of the rough or garden variety) they are obliged perforce to confine their training to the mental side of hang gliding. Ah, the spirit is willing but the flesh is weak. So much for that -·not to say that we shouldn't hang-glide - but that the human being is better and more functional as a reasoning machine than a ballistic missile. We have to learn to control the landing mode to accommodate the frailties of the flesh. Now to the next problem of the thinness of 'the insubstantial air'. Assuming the usual California Zephyr of about 5 mph and that we can handle (or feetle since that's where the problem lies) a ground speed of 15 mph! we have an airspeed of about 20 mph to fool around with. Dr. Bernoulli,, . I that ineluctable Swiss Italian, tells us that this gives us a d ynamic prfssure, q, of about 1 lb. per square foot, not the most sustaining calculations. Now airfoils is airfoils, boundary layers behave in their immutable, intractable and generally cussed way, and one thing leads to another. In shortl most I conventional airfoils at Reynolds numbers less than a million cannot achieve a lift coefficient of more than 1.2, and this usually at the price of a tery vicious stall. For example, the N60R, so lovingly described by Doktor !I . Schmitz in Aerodynamik Des Flugmodels, goes from a lift coefficient of 1.1 at 13° to .55 at 150. That's rough sledding, matey. Assuming one can get an airfoil to work at a lift coefficient of unity without the drag of a : locomotive, that means we are forced to consider a wing loading of about! I 1 psf. Now for a 200 lb. all up weight we've got to get 200 square feet of lifting surface into the breeze. 40' x 5' ? That's a big canvas, Leonardo. Rough calculations for a ship with this wing indicate that with very careful streamlining one might achieve an L/D of about 8 - a very respectable performance, if only one could keep the ship pointing the right way. This leads into the general lumpiness of air. This lumpiness is all too well known, although- not much solid data is available. Some authorities of reasonable repute state that a mean sharp edged gust of about one tenth wind speed can be expected with a scale length of about 30 feet. If we continue our analysis then, this means one might expect a change in angle due to a relative up gust of about 1 1/2 degrees. Now consider a 40 ft. span ship subject to this one wing only. We find this produces a rolling moment of about 150 ft.lbs. Assuming the agile pilote can extend both his legs to the full side position to counteract this. he might produce a barefoot restoring moment of about 30 ft.-lbs. or even in the heaviest army clodhoppers 40 ft.-lbs. (or 2.0 leg boots). When one considers the time lags involved in the development of the new wing flow, and in the vehicle, and in the rather slow moving cortex cerebelli of the type of person who would, of his own free will , project himself into space, one sees that controlling the lumpiness of air, at least in the lateral modes, is a pretty forlorn situation. Wot to do? Aileron control seems rather hopeless because of the time scale involved in developing the new counteracting wing flow. What we really need i:1 a. wing section where the lift is not responsive to angle of attack. This is not a new idea, it rejoices in the name of the aeroisoclinic wing.
G. 18
The basic system is that the outer wing panel is pivoted slightly ahead of
its aerodynamic center and the airfoil given reflex camber either by an upward deflected flap or by an auxiliary surface (like a little stabilizer), then, as the wind angle varies the whole wing panel rotates so that it always is at one angle of attack. This angle can be varied by setting the flap deflection, (this means aileron control is still possible.) A very appealing idea theoretically, unfortunately some severe practical problems occur with highly ca,ntered sections. Apparently part of the success of the Rogallo systems is due to the aeroisoclinic effect of the flexible lifting surface coupled with the rather lower characteristic span of this type compared with the straight wing.
As always there see~s to be a gene~al ]_aw
of the Conversation of Discombobulations. In the Rogallo one pays for the lateral docility ty the prohleos of a large chord, meaning that you have to scurry forward and backwards along the hang bars to exert sufficient longi-
tudinal control.
This seems to he a fact of life in our game - you need so
much vling area - if yot~. cet it ·-1:i th spa.n you Get late~al COlli.1i1--1tions, if you
do it with chord you get 10:1:;itudinal inflexibility, to say nothi.ng of a very depressing induced dr·ag scene. ally described in :1_is o~.'.1 n writiEt;s,
plane. This deserves considcr~ation.
11
:::
ir: his own writings,
for -the Dcvelorment cf Hu;:;1c.1J1 F'lif:L.· 1_. n direct]y ::.'.tate2.:
It was these consi6crations, specific1·i caused Lilie:-;thal tc, adopt the Ci-
:.1} 1 :
1
( A.c::.;:·onau t.ical
11
Fr2ctic3]_ F:Yi)erifllen't.s
lmnu::il of "1 E/J(.) Otto
The ide2, occ-;_;rre,.::'. to oe to appl:,:r tv.ro s:naller surf2_ces,
both l1~ve s liftj the airn .... this ·,i.'oulG have tl1c :-:arr:e effect ds "a si:'lgle st;_rface of tv6ce the bearing capacit.y
but on ~ccount of its small dimEnsioLs, this apparatus
obeys ouch bettei~ tlle changes of r~:entl'C of gravit:,r. 0
Le Jic'. net use t!1e bipl3,ne cellule for str1.1ct1.J::.~2,l reasons, .?_s V-.'C' s the oot.ive in tht: \1r.r1 fit....:~:.ter _ In fact, pl1otos of his Qac~:i~e 2how ve!y clearly that ther·e w~s mi~irral
.interplar1e 1:-rac in[, '.:lrtcl 1:.
~he u~per ~ing w~s p1'incipally loaded as
cantilever .. It is witti these ru~ir12tior12 tl1at
y0Ll1·
scril,0 c:1(~ t:is di2t.rite.
~n~ards~
upwards 1:.ri genLly.
Wh8t we need a~e:
• Soft landing devices
• ke2lly good low Re airfoils • So~e means of cornbatir1g lateral disturbances With the above fat·i.Jous recom:112ndations, Aasvogel retires to l1i2, eyrie 2nG Lo his other research ventures. More trivia will surely follow. From 6_6 landing skids or wheels which could allow the operator to retract his rnnninQ ge;rr during Hi_ght. The skids/wheels should lw far forward, alas, which may ft'.,ult in some torn trousers ancl skinned knees hut reduce .glider clamaQr,. On landing if it becomes necessary for the pilot to make a hun:iecl rear P.xit, he must beware of the half loop th<:' machine will perform on its own, A football uniform might be
,1ppropriatc dress.
In conclusion, we do 110/ have a to,hcre. Ccrtainh- Otto wasn't toYinu; ~1ronrnL know tha-\ he was dead]~- serious. It should be noted the \I/rights- ( who knew
,n-
disaster) both died in becl. Those who run and leap into Aeolus' arn1' need lnck more than most. If one flies hi:.d1cr tkrn he can jump, then it should he in a cLhsical moclern design, which, all things considered, is by no mean:; foolproof, but still more so than hanging from a shoulder-mounted curtain stretcher_ Vic S,n.:n£:: Inglewood, Calif.
Safety Service lThis section for our protection will be a permanent fixture in the l.&S booklets. Each booklet will provide something that will assure us of continued existence. L&S will not hide potentially interesting airways just because unwise acts might be dangerous, b~t will always strive to make interesting airways safe, even when, at first, danger seems to be the prudent object of concern.) 1. Add fueled devices to your flight systems and run the risk of that device failing you at the wrong time or in an explosive manner, A system of fewer moving parts has less parts to fall apart. The most simple systembas fewer parts to maintain. Angels don't fail to fly; although they seem to have had the ability to fly too close to the forbidden tHErmaLL •...• this being because they had at least one partthat is, their angelic spirit. However, their God seems not to be able to fail to fly everywhere at all times at the same time .•.• most probably because He is the the only Being that has no parts to fall apart. We might let this be a lesson for all of us, for we are made up of trillions of parts that can fall apart for billions of reasons. 2. We wish Bill Bennett a speedy recovery. Most unfortunately Bill's fueled motor-boat towed launch on July 4, 19'/1, ended in a body clash with some rocks. He told me he will be all right. Bill was not flying his reeular kite. L&S recommends flying over terrain at speeds within one's running speed ability, especially when flying low. Try no fuel. 3. Chuck holes while hiking for flight trips cause more damage than one would at first give credit. Snakes in the grass can be a problem. 4. Have you ever hea:rd cf Eagle Kill i'.nee Will or We Nil ? Anyway, he is some powered cat that thinks he I s a bat, but he must always contend torques, sparks, octanes, and getwampers. He still has a bone left. 5. Don't be willing to fall in such manner that it hurts.
6 .. POWER TO THE PEOPLE-----put fuel aside.
Look: People can flyl
7. Good safety potential: A Heflinger wing recently provided 9 beginner glider pilots with 3 solo take-offs and landings without even one emergency alert. Comparatively, many minor sport first lessons bring inJuries. However, let it be known to all of us that a solo flight in unproven systems under poor conditions can bring disaster •••• not unlike the fatalities caused by baseballs hitting unaware players. 8. Fly low enough to be saved in case of emergency or high enough to permit your safety emergency system to become effective reliably, If no reliably effective emergency procedure is at hand, then fly low. Ridge scaring in a ship that is wing-loaded enough and controlled well and is well tested for expected stresses can be an inexpensive low and slow ship home made; but an inexpensive low and slow ship home made does not automatic~lly qualify for ridge soaring dependability. You and your ship can qualify •••• but if you don't, and try, then you won't. Ridge soaring as in the centerfold of this booklet can wait until many skills and factors of reliability are learned and carefully attended to. The delights of near-ground low-speed activity in a picnic style holds hundreds of chances for the creative person.
9. Fixed-anchor tethered flights have their peculiarities distinguishing them from free-flying-anchor flights. Ground speed on the first is usually zero whereas only rarely is g.s. zero on the second. When hitting the ground from the first one has only a vertical force. On the second, one has a vertical and horizontal force vector. 10.Since a body moves fa:steir air.d faster as it falls, that same body:will hit the ground. harder and harder ~ e.epenolir.g on ,ilta fall distance. 11.Fly systems in a manner safe for spectators as well as for yourself. 12.Drilling spars weakens your structure •••• especially wood spars.
I
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