USHGA Ground Skimmer February 1975

FEBRUARY, 19

IMME

ISSL..E NO. 25 FEBRUARY, 1975

GROUND

SKIMMER

8

INSTRUCTORS' FOR UM, and T rip Mellinger

Dan Chapman. Bob Dart.

BIG SOUTHERN BUTTE MARSHMALLOW FACTORY. John Dunham

10 14 24HMA

I

THE EVOLUTION OF THE I CAR U S V, Taras K1cen1uk.

Jr .. and Taras K1cen1uk, Sr.

f

NEWS, Peter Brock

A BETTER MOUSETRAP (A new safety release system), G reg Brazier

26 30BOOK 32 34

REVIEW, Mark Langenfeld

14

BUILOING AN INHERENTLY PITCH STABLE KITE, Chris A. w ,11s

HANG GLIDING EXAM, Pacific Northwes t Hang G lider Assn DEPARTMENTS

2 U ltrahg l1t Conversta1on 22 Pho to Gallery 28 Tech T,p - Mike Skahan 43 Classified Adv ertising 44 Calen dar ol Events

MAGAZIN E STAFF Editor: Carol Boenish Price Art Director: Ric h Gngsby Production Editor: C hris Pnce USHGA OFFICERS President: Lloyd L,cher Vice-President: Kai Dellsse Secretary: Carol Velderra1n Flight Director: John Lake Office Staff: Carol Velderra1n. manager. Chon Aranda. Susan Mann. and Ronda Leggett.

THE COVER: R,c h F,n ley, Phantom Jet Pilot. pil ots his custom \Jes ign Wind Lord 1n the skies above Torrey Pines. Cahlornia .

Photo by St ephen Mccarroll

.. mi

- ........

28~

vI

wing

shape from

want to venture for prnl'it involving an orni1.hopter tlosiµ;n using lightweight motor.

pressure) on that

progranL Booth rosorvn.tions be made by March btl!. note to pilots it important for both bi!,torieaJ and that in the prog.rarn, entry blanks We can't potential benefits to be derived from tbis event with

$GOO $400 $200 $100

Competition starting on level 1-sround with no wind!

Lt interesting to note that the world record for made by glider, but it couldn't off without tow. That is the stumbling block, and il you every tirno. Just with tlrn !mug glidortl that now Jly and thotlo beautiful varia.tions t.lrn.t bound to como oJ'f t.lrn tho future, tho

exl.remely J i11;htweight motor (nrnybe Wankel type) that eapable of controlled flight, ofl, bird,li.kc hovering; gentle ea.pability. l lnwe my own but I'm just of thing a.nymorn and who might 0110,

competition.

]

!HJ.VO

oniil.hopter was tho the postlibilitie,, in

ptorodaetyl to the eolm· to comp.let.e Urn ta.ko specia.l pride in h,,.vin,r cn,1h'·ih11t.m•c, l ilrn l ,loyd Lieher. the letters and articles l~aeh reading brings awareness and understanding. I want to encourage pilots to review back itrticles and oaeh time they learn something and expecially when they foe! they have Imel close call.

Organization, self-rnguhttion, a.nd improved glider design are shaping up rapidly to bring more, mueh more, than quick glide down the hill. I am fortunate enough to have cake and eat it too. have been J'Jying tlailplu.mrn for a number of years and own a Schweizer 1-2fl. summer my wife a.nd I rode a. nmtoroyele from North Carolina to Sylnrnr, I took my first H.ogallo training.

I.hon, have been flyinr-s frequently and au Icarus Tl oecasionally th1111ks to .Joo Carswell and Milne, members tho Morganton I'tiwm·lm,s Flight Company. We have been long·er and higher flights each Wl30l&.end loarning .... 8lowly.

There itenis eonoerning would like l.o touch upon. First l

rnost conunon (Contimwci)

FEBIU.JARY,

irn press ion he ,mfe operation in

below Oil tllll

an of callin entry door. *Minimun1 airport are2000 longth, 60' width, be Joss .in length Jor STOL aircraft $100, tmnpon1r,y

Plentl interprets the oxisi,ingrmrachutc and regulatiom, to include hang· hi;, way, iL may oJfect and sproa,d to other

la.wnow of HHHl

for Co1 r1plete line of aC()essor·ies 1

now known or lloroaftor invented or designed navigation of or flight in the includin/~' parachute or otlrnr contrivance, designed for sport Jumping or manouvori ng· air at an altitude tlutn twenty-four above loveL The folowin1; tllo amendment to this law: contrivance now or of flexible without tl rn or otl!er mechanicaJ propulsive which designed to utilize the foot and leg's of the operator the sole moans or initiating forward motion l,wncl1 ,rnd of providing' during point of contact with Uw ground upon cornmonl,y led a be included within this definition, ra,rnng of this bill could The Virginia, flyers support, I ,tm asking the our friends Ohio Hang M iclwest Hang lidor Hang

m<1,1a,•,<>1 and hardware on hand if you

and build your own

regulation of hang

USA

Adclrnss your The Hcmon1blo Campbell, Chairman of Urn

Tnmsportation

P.O. 11 Aslllancl, V iq1,·inia ,John Winkler Ohio I·lan14 Glider 1u;sc,cia11on

1::1royw:s, Dal las,

and Davie! ,Jollnson, rm3trtplrn:0n,:e Llmt l !a.ng 1taLrn&ts

not achievonwnt awards. pilot to a. or minimtm1 witnessed. l n no way do Llrny indicate Urnt t.lrn pilot not

THE NA'1'10NAL the last

printocl. a should be notod anvcmiJ oxac:til v how tlioy should sbou Id bn ostahlislrnd.

make observations which responsible contest At responsibility tho the committee know that likelihood of rnall.Y µ;ood w,mttwr a.t the It

fa.ct that know ,tround the country. examiners mny ot· may not act as instructors or observers. All help in selecting exami1rnrs will be appreciated. In mnking

B N A L O V

U W A

E p

R I

A B

T

E

N

s

eBuild the world' fi tro 11 ab'I hang glider.

I

L

L

NEW

ful

·1y control l abl

control 111A 11

eCan be built in 6 weeks time.

•Material cost approximately $200.00.

meta 1 , bui gl·ider.

l'l7S

I

We feel that it shouldn't cost you an arm and into the nation's fastest Neithm sl1ould it Consider

in1,i.1"11,·,t.,Jt'.<: in

today , , t lw

m,1:uleqrrn:mos. n11d irnpl'oper proced1ires.

SAli'liJTY lJan Clmpmm1

The Hang Glider St,orc

It seeins to me that the only way to bones, Limo in tho hospital your style,whetlrnr endless Jrnssols from the

how of.hers teach and Uum

up with a lmsic 1..mid,oli1w

.for fligl1t schools t,o lo.llow.

011e of' tlw main purposes or Uw

wns tlw of idoas, No ono knows all n./1011/, lcmclli11g, a.11d nil hn.ve good Sevoral instructors pr0s01Jlm/ what they i'elt was most 111ot110d to parU011 lar concept studcmls, Wo discm,sml

As

gliding.

Thero are throe c.) aUitudc. a.) The equipment must be with care and a.ttontiou 1,o detail, materials. For example, aluminum am! constructed to plan. The sail, however, had 11 rostr.iotion band 8own tra.iling edge. Tho cupping effect w<Ls analogous to down elevator, making the kHe pitell (partieularly nose heavy). Unfortunately, cannot alwa,;ys count on rmmuracturcrs to provide well.proven equipment.

The sail described in the previous paragraph was purchased fro111 a wel I-known nrnnufaeturor. Today, oompanles are selling safe equipment.

The necessity of helmet student may ehoose not no longer under my instruction for the proteetivo headgear. lJ.) The seeond aspect of safety from gaining personal flight oxmn'ic11,ee about the sport. There available to the :,;m·,,,us . lrnto\vl,,cti{m1.bJ.e

They are encouraged to join tl!e and local Included printed sheet deseribing the assoeiations and their addrosse:,, 8

also gained and pi lots (mJV!Cc.1s meet orton "Why should listening to of eonvenmtion gerH1r,1,ted 11t irntiet,s,much to be rn1..u·1w11. Ono complaint l ha.ve tond to group and slnm students heitn1 tha.t other out8idors. While there truth in this, feel that most. pilots will respond to sincere questions and comments. c.) final point on perhaps tho most important,,. attJtude. sa.le a.ttituclo is a fl'anrn of mind in ,tccorda.nco with which procodure8 a.re followod a.nd arrived at. This the two. l f point

in coming- in for a landing at a.

I then

tlw

" in

excellent to print /,wo three suc/1 in overy issue of G HOUND SKIM ME/R. All pilots and pcospeoti ve will benefit from this ini'orumtion, t1oi, otlwr instnwtors.

pro/JJo.m Hang Urn Photo Rich OrigslJy

for

the

flight.

This

SA'l'URATlON whieh

"not for la.st long in approach flight with help develop th.is safety their students, then they have done justice to those our sport.

properly control tho craft, lc1Lalrn11ore,n1e11t1berwha,t the flig;ht Pi lot Sa,turalLion his first few flights until answered, his ,,,,,r,,,,u,,,, the job at hand, and ho At this point, the student eoncentrat ing on norfr,el.i no· tho sitf'ot,y factor of o,wll [lj gb t.

Tho number ol' flights required point and develop proper student be sig·11ificantly simulator in our pre-flight instruction nrocedures. using this device. we c,m the individual's first Hip;ht d111na,ged trainer. introducing hy using a F'irst, the student feels the sm1s1•n1on the glider and attached prone. He may determine onto the control har and position While the i n"t.1·111,trn' the glider, the student feeling hOW !nllCh 11l'PS:,ml'P where he is to move in rela:tio,n

SIMULATOR Melli11gor SoutlieI'n c:a111c,n1·1a School of

glider flight, thi.nk bitek to few momonts before started running the glider down the hill and into the air for the first time. There prob11b1Jy

to which way lfl··.ITiffht corrections. first flight, runnin ..i: through mind--so many, that it hard for him to a,ttention to the procedure he has remember

a certain profici:erw.,, l,Dvo l

to having not used a simulator in buHd one for your school, lam sure '"'""v uc, improvement in tlrn loarninr4 capahilHios of your s1,111ucrn1Ls you will be rewarded many buLlding such an important device.

Be snrc that the simulator build flyi.ng hang glider much shock absorbers attached from suspension frame work well for

'l'ell11ride, Co.lorado, .MouIJtain Hnng one of those plaees you in July, 1974.

hate

because you're this must be

promptly !'el.I

wondering

in hell

the

ly

in my hanpnock slung between two

Aspen trees, some before our last morning in the Rockies.

Jom;s and I were tentatively pfa,nning to leave the m;xt day to scope out some new flying spots in Arizona's White Mountains before headh1g home to Diego. my dreams to in f,convers1ttion witti Short, winner of that da,y's con1,est. Bob was talking: "Come with us to the 'Butte,' ,fohn. paradis~il The most outn,geous pla.ce you'll ever fly! It'll be great place to take your "Wind Lord" for some country flying! 'rl1e only d.irection the itir goes out there up! lllvc;rywlrnro you fly there's lift. Thermals! lift!

It's unreal[ There's so much lift you cou Id drive to the base of the mountain and fly upl Witllout your k'ite!"

"Sure, Bob," sa,:id I. "What w:as it you imd the gang were at t1wern tonight'? a drinking contest"???"

Well, half: or not, I wasn't to let all thi.s exc i. ting· talk ma.k.ing a rational th.is seem like

along behind ctmnt,ing, Butte" in harmony.

Arriving· .in Idaho 1"£,lls on Wed1rnsday met with the kHe from

generating luiat into average afternoon ,you can dust devils large as white tornados being sucked up seemingly into fluffy white marshmallow clouds lined in far the can Out. of this ocean of nothingness jutts three volmtno· like mountt.ins out fifteen mileic; the desert. The west of these hills, South<irn Butte," to base. This hill ha.s a pitssable dirt which wHl any face, bowl

Throwing; to go ... but who's, bmm wind dummy tho last proceded to end of tho watehed the

1,ntt hovering a,nd After a.bout fifteen Miko and I had 1200 feet

an eirni ting

crabbing out mountain to the north and lHHtdded landing four miles away,

the mountain, my altimeter now read 3200 above the desert floor. Everyone headed for the cabin, .more or in stntight line, playing around for long Urne until they landed on the airstrip.

Meanwhilo, with my on a sunny patch of ground and doveloping cumulus, l headed downwind of everyone else and to the needle on my altimeter np to 3500 feet I headed out ovor the flat cle,;ert.

There l was, arJOO feet. up and wondering· where to go next. There wa.s no need for a. variometer boeause the lift seemed to bo everywhere. Aftor flying around sort of pointlessly, I turned a.round and headed ba.ck to the landing area and found the head winds too strong to penetrn.te. Then and there ma.de up my mine! not to fight it. Turning downwind, l hen.ded for the cumulus cloud which wits looking darker and l a.rger all the time.

was looking at the base of the cloud and getting· a hove perhaps f500 face. Due the fact that heavy rain in on and that I was getting I had no faster and faster rate, I sucked up pointed my "point-nosed para.chute" clear sky.

Brea.king out from under the cloud, my sail inverted violently and l was thrown a.round a hit, bnt things smoothed out quickly. There was a surprising temperature change now and the warm air felt good for while.

Seeing tha.t my altitude was dropping at sickening and because the cloud was now between me and the highway to to the north, 1 decided to go for another swirn. Wham! Through the turhulence. under tlrn cloud and it was elevator time again. Getting cold and wet didn't seem to matter anymore. You never saw a ha,ppier, more free-spirited

upwind and settled down gimtly next to the camper of an older couple who were headed west on their summer vacation.

With gTin from ear to I walked up to their mmiper and said, "Hil" When they asked where had come from, I pointed. that mountain way over there'?"

"Well, I took off from the other side of it, flew up to that cloud, and .finally ended up here!"

The couple looked at ea.ch other 1u1d broke out laughing. They as keel if I needed any help.

"No thanks," said I. My friends should be along a.n;y time to pick me up. Thanks anyway."

After they drove away, l sat down and looked at the cloud l ha.cl just passed up and the mountain from which I had come.

'I'en minutes after I sat clown, the cloud pl.eked up skirts and threw ao mph

SCAH Ii

For as far as I could see there was nothing but desert spotted here itnd there with Atomic F;nergy Commission lnsta.llH.tions and a few dirt roacls.

Ten miles to the north of the Butte, the n:rnin highway cut through the desert. I figured my best bet would be to head for the highway and follow it downwind, but for now I wanted to play a.round with that c.loud. Ma.ldng a few long passes undernea.th it, I was surprised at seeing the needle on my meter climbing at a very fast rate, and getting faster all l,he time.

Nearing the base of Urn cloud I wa.s beginning to worry.

The wind was getting interesting, to say the lea.st. At ono moment it would feel like there was a strong head wind-then cross, tail, and every which direction. There was nothing violent as far <1s turbu.lence goes.

At my highest point my meter read 5,500 feet over the desert floor. At that ti.me I 12

pi.lot tlrnn when I was under that cloucl.

There's something· a.bont being in the air more than a mile up and not worrying where or even when to land. If only there were were other clouds like this one downwind, I couid have g·one until sunset.

With confidence in my machine and in my ability to cope with the situation at hand, the sllacklcs were off. I was defying gravity. So it seemed for a. while. This had to be the most refershing, exhiiia.ra.ting experience l had ever enoountered in my life.

Aft.er regaining· my a.Ititude of MOO feet, decided to fly out of the cloud. sett.ing· up max glide to the ma.in highway. I almost turned a.round to head hn.ck to the cloud to play some more, but flying prone for almos1. an hour sometimes puts a strain on one's body, and ti was time to go for distance.

ll

/J

.10

Mil.ES

w:inds and the heaviest rain squall I'd ever at rne. With a thundi,rous voice, .it seemed to "Take that!" and headed slowly off to parts unknown. There l sitting on Urn ground wishing I was going with it. it turned out, had gained approximately a600 feet and traveled 11 miles downwind of the mountain. One of these clays, hopefully next summer, I will encounter similar conditions. l hope I'm little more prepared than I wa.s la.st .July.

It my dream to become knowlodgeable the birds we're trying to imitate in this sport, and to be free to go where they g·o. feel like a guest in their ocean of air, and I'll jump i.t any opportunity to lea.rn firsthand what, comes to them naturally. My thanks go out to the late Lloyd Short and my good friend Ilob Dart for initiating this experience in the ultimate.Ai. FEBRUARY, 197.'i

ABSTRACT

Icarus V evolved from observations of tho faults and virtues of viuious hang gHdors developed frnm 1971 on, from the !tpplicu.tion of classieaJ aerodynamic design teohniques, and from reoent developments in tdrfot! design technology. Tlw Otto Lilienthal hang glider get·· together showed that safe foot,launched flight was possible with widely confignrations, but thal, structura,l control improvements were sorely needed. The biplane, solution to problems illmninated at that event,, demonstrating the positive attributes of the flying wing. The second version, the strncturally improved Icarus II, showed thermal soaring flight was to be achievable from foot launch. The monoplane Icarus V was then built using a. speeial computm.·,derived airfoH with high lift and low pitching moment. Longitudimtl control comes from weight shift; lateral control is achieved with rudders itt the wing tips which combine with ,wroclynamic stability and closely couple bank and yaw. Stall speed mph while maximurn speed in sl,ill nir fiO mph. Best glide ratio is 1(), minirnum sink is ft/sec, and G0° banked turns ca.n be held indefinitel.y, lNTHODUCTION AND FIACKGEWUND

The course of early aviation history as regards foot .. launched fli.g·ht is well known and documented (l,2). It is the purpose of this paper to help round out the account of recent teehnological and historical developments by focusing; on the evolution of the high performance, foot·lmmched glider, Icarus V. In celebration of the 123rd birthday of Otto Lilienthal in 1971 there appeared on a hillside inCalHornht ,1 motley fleet of home builts, the likes of which had not been seen in fifty An 14

l'EBRIJAlfl',

that attHude cffoctivc for this class of eraJt. The Chanute replicas of en 1ci1en.ey point enlclrt31V ,w,"'"'"14, While abounded. Strueturn.l integrity of frequent loops and hal'd landings with the that ta,il booms semi and heard popping

by control which clearly pointed

Urn problems and

eombined performance way (or future l:rnrig glider

event.

ma.ny other mostly structuru,l, discovered for the first time. decision to a,dopt biplane configuration wns based on two primary conf;,itior·ations: { 1) Miller's "Conduit Condor" exhibited srrmll, hut noticeable longitudinal oscillations at the frequency and in phase with observed twisl.inri; of the wing This taken that torsional eomplia,nco of the prevented the w:a.shc,ut from beinµ; an effective a.id to longitudinal stability. It sug~;eE,tecl that migllt

section only on the laminated wing ribs fabricated fm· this purpose too to bo uHod without extm·ntu connpresswn this was nbandoned in

natural location outboarcl interplane sl,rut..

wing prompted n1·acl.ir,n.l on(:}8 wore: ( 1) Miller's "Conduil.

in tile event wlng·ed craft directlmml stability.

Longitudinal stability to be achieved combination of and through tlm of airfoil H should be emphasized that there at that time no firsthand infonnr,tion by which to standards 1weepta.ble "handling for type under Um of fligi1t being anticlpftted; (running) testimonial to the rapid the pilots and to the nr)l'forman.ce

horilrnnta1 distance between might hilltop, angle of attack coupled vehicle with I.hat condition. of thu

wind spccu1rm1ar fligllts, the promise c!<Jmo111,tra ted by dr,H,Vv'inie: board,

DAVE MUEHL

di1,C<Jrti,Jc1tinp; property of the biplane configuration the poor visibility

cut out

Witl1 the foregoing in mind, a c:on[lguratiou omorged,, the monoplane lcaru8 V. upper woight limit of seventy pounds with Icarus II, of Ul1Lrl'l·t'WO

problem! tlrn upper 8tr11tt<:irc! (9, to),

MIKE MITCHELi

KENT TRIIVIBLE

THE BELL SOARING HELMET IS AVAILABLE THFWUGH Your, LOCAL RELL R. Distributed world wide by Eippor·Forrnance, Inc, 90501

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search for better stall. Figure shows the out;lino and pressure distribution of one of the many tried. AL this stage the design process the not .vet free of pressure peaks the loading the section a,s fina,lly employed on

I RFD! L

Figure Tho geometric twist to produce an ideal spanwise lift distribution for the constant chord wing was calculated to be using standard teclmiqnes for swept wings. The ohserved fligt1t performanee suggests that this choice good ,tt as the resulting longit.udinal stability and stail concerned. Icarus V has been flown by at high altitudes with very "forgiving" handling qualities. The craft will not stall even if Urn pilot ,issumes the full rearward position, nor will it "tuck under" with the pilot full forward; in fa.ct, with the pilot in this forward position airspeeds in of BO mph have been

Perhaps it in Um ii.mas of handling and control that Icarus V has most to reveal. rt wetJ .. Jrnown fact that the Wright Brothers "unlenshcd" the development of lleavicr-l;lum·11ir flight when l,hey substituted proper aorod,ynarnie controls for the earlier weight-shifti.ng technique. Volmer .Jensen demonstrated thirty that these same aerodynamic controls coul cl be used on a foot-launched glider.

By ta.king fresh look at the question of optimum control s:vstEm1s to meet the ultralight footlauncll requirements, ,whieved which may, in turn, look at the problem of low speed spiral flight. '.f'o pla.oc the control of Icarus Vin proper perspective should back to the first Lilienthal hang gliding meet (197l) and examine some of the results. Although 11.11 of the pilots prob11,bly nurtured secret hopes of sustained soaring flight, the immediate goal skim down grassy slopes with sufficient longitudinal and directiorn1l control to avoid crashing into automobiles belonging to the nmny speetatnrs. Many of the would"be pilots had no flying expericm<)C whatever, and one the app,H1ls of the sport was the promise of self-taught well self-sufficient flight.

FEBRUARY, 1975

For more information and free literat1Jre, c,:mtoct/oSw'lDeoler nearest you.

mentioned before, .longitudinal stability presonts no problems, longitudinal control. The limits of the weight,,shifl; method should be recognized, however, in sov1~ral situations, During tho take off run, the craft tends to assume nose-up ntti.tude because the mmter of gravity of the em.pty craft far behind the position of tho center of gravity of the pilot-plane oombim1tion, When standing, the pilot supports the weight of the craft in the smitll of h.is back airspeed increases, the pilot maintains longitudirrnl trim by puslling down on Urn twist grips, which he holds wHh his hands, Once airborne the intrinsic longitudinal stabilit,y and the pilot's weight shifting ability combine to provide excellent control, even in unusual attitudes, Oneofthc towinglms frownedupon ameans of launching gliders is that angle of atta.ck control by weight shift is vcr.v Jimit.ed iit steep pitch angles at low speed.

In the event of tow line failure or wind gust it is almost impossible respond quickly and effoeti vcly enough to avoid sti.lling and crashing, Perhaps experiments with auxiliary towing surfaces towline attaehment points m111 solvo this problem. F'or the present, this class of fll11;ht would seem to be denied to flat land dwclJers, Similarly, intrinsic aerodynamic stability is important. The stability and control wl1ich can be achieved normal flight a.ttitudes by using low center of positions vanishes when those attitudes become ext;rcmc, as dive or a sl.ip following i.n ,,brupt stalL How,iver, one bonml! of the weight shift method of longitucinal control which shouliJ be pointed out that il cures the flying wing of one of i.ts most serious drawbacks, Normally aerodynamic controls such elevons tricky to use cl uring ta.keoff a.nd landing beca.use the immediate effect of control movement is to eause a response opposite to that being sought Up elevon causes a decambcring effect the a.irfoil, reducing· its lift at the same time as it rotates the in pitch to secure more lift by micnia.e:ing its of a1,taelc Pilots who ha.ve flown tailless sailplanes complain of difficulties 1it those critical times and

of the "porpo.ising" that commonly ocom·s, Spiral or low speed flight also suffers because of this s11,me effect which is necessu.ry to secure high angles of attack. ln case of lcaru s V the high cffi eiency airfoil i.s used in its exact design configura,tion, Also, spanwisB Jift distribution is not aHBrcd by changes in control surface deflection along p,1rt of the span, Although no flight test d11t.a are yet 1iv11ila.blc, Figure prc1sents the estimated performance figures and speeifications which may provide some goals 1md guidelines for future dev!llopments in foot-launched gliders, ,ACKNOWl,EDGEME7NT

The authors wish to aeknowledge Urn encouragement and ass.istanee of Panl MaeCready and PctHr Lissaman and their offer to make available the cxotJllent facilities AHroVironment, Inc, HEFEHEJNCES (1) Poynter, Dan, Hang Gliding, N. Quincy, MA 02171,

Dan Poynter, 48 Walker

(2) MiUer, Ftielrnrd, Without. Visible Menns of Support, 1967, Parker a.nd Son, Los Ang1,les, (3) Millor, Richard, ot al, Low, Slow, and Out of' Control, Volume l, Nos, 1 through Ei, 1967, 1968, (4) F'aust, ,Joe, et al, Low and Slow, Volume 1, No, l, March 19'71.

(5) Lambie, Jack, "Downhill Racer," Soaring, Volume :34, No. 12, December 1970, (6) Eiffel,

NouveJ/es Heehere.lws

la Resistance do L'air

L'aviatior, HJJ,L (7) Weber, ,L, "The Calcnla.tion of the

Distribution over the Surface of Two-Dimensional and Swept Wings and Design of Wings with Given Pressure Distributions," H & M 8206, ,June 1955, (7) Weber, ,L, "The Calculation of the Pressure Distribution over the Surface of Two-Dimensional and Swept Wings with Symmetrica.l Aerofoil Sections," R & M 2918, ,July t953, (8) Weber, ,J ,, "The Calculation of the Pressure Distribution on the Surface of Thi.ck Cambered Wings and Design of Wings with Givon Pressure Distributions," H & M ,'.1206, June 195fi,

(9) Stmtford, "The Prediction of Separation of the Turbulent Boundary Layer, Journal of F'luid Mechanics, Volume 5, 1959.

(10) Stratford, BR, "An Experimental Flow with Zero Skin Friction Throughout its Ilcg·ion of Pressure Hise," Journal of Fluid Meclnmics, Volume 1959, (1 l) Lfobeok, RfL and AL Ormsbee, "Optimization of Airfoils for Maximum LHt,'' AlAA Journal of Ail'omft, Volume 7, No, September-Oetobcr 1970, (12) Lieb(lck, RR, "A Airfoils for High Lift in Inoompressible F'low," AIAA Preprint 7:3-86 Aerospace Soicnces Meeting, Wa.shington, ,January 1973, anyone interested in obti.ining plans for the Icarus V, write t0Tan1.s l<ieeniuk, Box GS, Pi.lomarMountain, CA 902HO, The cost is $21 if sent by 3rd class mail; $22 for 1st c.lass; nnd $23 sent ovBrnea.s by airmail.A

20

FEBRUARY, 1975

(714)

(714)

11,IJ

22

The final Ha,ng· Glider Manufa.ctnrers meeting of the season was hold on Doecmber ln conjunction wi1.h the National Clutmpionship,J. The main topie of discussion was tho revision of Category Spocifioations, tlrn first point being tlmL Spoeification ii1 control b,us needed clarifieal.iou. A commitl.ce of Albatross Sails and Trimble of Manta Products nppointed to rewrite j1,,

A seeond point brought up tha.t rnost HMA members fol t, tlrnt the night maneuvers for HMA cortifi cation of C11tegory One r;liders wore not string·cnt onoug;h. Dave Muehl of I<]ipperFormanco, Ine., suggested that a of Specification I tho Flight Control Hoquirements be made to ineludo a pilotinitiated full brea,k stall a,nd Tho 1tddition now

"Demonstrate full break sta.ll nnd by diving /:\'lider to build up speed, brin[,l' g·lidor up to a,t lea.st from horizontal with of speed. Allow nose to fu.l l through an of approxinmtely BU 0 and then dive to reeover speed and flight eontroL" A third revision concerned aerobatics in ilang gliders, Mike Higgs of Se,tgull A irernrt and Wi Us of Sport Kites sugg·est.ecl that a "no stunting" notation a,clded to tho HMA fli.ght disclaimer. However, the definition of stun ting would be left up to the ma,rrnfaet.urer. The diseiai.mer now roads:

WAHN ING AlHCHAFT IS 'NOT FOH AElWBATIC is 11. dangerous ,wUvity and ean result in serious injury or deat!1 even when in under irlea.l circm1u,ta.11ccs.

Tllis equipment manufoctured in ftceordance with the safety, material, construction 1u1.d flight standards established by the Hang Glider Manufacturers Association, lnc, Tbis equipment sl10u ld be,usecl only tmdel' proper conditions after proper supervised instruction and practice from hang gliding instructor. The rn anufocturer has no control tho and maintenance of equipment and all persons using this equipment all for t1a.1nag·e or injury. The manufaetu rnr itnd the HMA, hle., disclaim any liability or responsibility for da.magos or .injury resulting from tho of this equipment."

Kent Trimble of Manta Products noted that there had boon a typographical error in Specification #11 concerning tho eoding on a.luminum tubing so this was clrnngecl to read "T8:32" instead of " Kent itlso pointed out that tho spec should more clearly do f ino tho tubing for glider contructim1 and spccifieally tubing, election held for two opou positions on tl!o HM/\ Board of Directors. Bob h.ee.lor Aircraft, ,Jon Mc Vey of l<'Ught Hoalitios, and Bill Bonnett of lli 11 Bennett's Delta Wing· Kites G lidors worn nominated. one of tho most unusual electious the three proceeded to tie oaeh othel' for thnm rounds or Jt. l'inall,y that t.lw Board be expmided by hm,rti.ly approved by tho the Board to mmnbors which Ultndite Products, Will oISr>o1't }(it.es.

Wilson of gippor·l"ormance.

THE BASIC HANDBOOK

FEBRUARY,

anodized 6067 ·

*Patent in proqre_,s

6044 • CONCORD, CAL/FOHN/A

h

y This article written to familiarize himg glider pilots with a new quick rele,um sysl;cm that a,t the least mights1we pilot from broken leading edge and hopefully nmy save a 1Jfo or prevent injury to a pilot.

Hiwing a few water and treo landings causoc! by Jnexperience or ttw fickle winds oJ Mother Natnre, and ft few more broken leading edges (a few my own) due to ground handling in J1igh winds, I folt the need for quick rolettsc system I.hat would enable me to release instantly from my wing in an emergency, but Urn.t would still have a secondary safety system to proven t imtdvertant release.None of the quick release systems in use met tlrn HMA requirements; na,mely, "secondar,y safety system", l t bad always been my worry, a.nd probably the HMA's also, tlmt t,he lanyard in the older svstc,ms would aecidently get caught on a lte I met or harness during take off or while flying and cause an aecideutal ,u,,m,,.,, While this would be R remote chance, fo,lling free twice from your wing would also be a remote possibility: there just wouldn't be a second chance. However, there a definite for a quick release system since many pilots 11re flying wa,ter or trees and in high winds, After the .HMA published theil' ruling on quick release meclrnnisms (and I wholeheartedly endorse their recommendations), pilots had two alternatives: return to tl!e old standby "D" ring (carabiner) continue to use the than,lOO'Y<·sa.fe systems or old. As we a.11 knew that the "D" gTeatly hindered release from the wing in any condition other tlrn,n totally slack tension, and use of the old style releases wa,sn 't approved, the search for a, better "mouse trap" bega,n.

At first the interpretation for the HM A's ruling was vague i.n our minds. Did they mean Urnt r, secondary safety device should be something Ulat would attach the pilot to tho wing at soeoml point and thereby prevent Urn pilot from falling free from his wing if t110re were ,111 inadvertant rnleaso? We sailed tlrnt taek for some time but kept coming up witb de11,d ends or exorbitant prices for systems that might or might not luwe towed the line. We began to fool that the problem was really a,n inadvertant pilot release more tlum a double hook,up Hvs,.e1•n1. so we a.imod in 1,hat, direetion. We tried various lanyard placements, velcro tapes and ohter assorted nifty gadgets, but none seemed to be foolproof or inexpensive enough for the average flyer.

We had almost given up when one night, deep in despair' OVfJr our lack of suecess, we were quaffing fow root,-beors and EURE!KA!, H came to us.,perhi1ps saJety system similar to that used in ,1 military hand gremu:le might do the triok, We experimont,ed and elaborated on that idea, ending up with stainless stool b«ll lock pin inserted 90 degrees to the direction of support in the requick re.lease meehan ism. This pin would

26

r

prevent the from opening no maUer how mueh tension put on the lanyard, By attaelling the lanyard to the safety pin and rel(;lase Jover, the system oould be actuated with one hand and must first bo pulled perpendicular to tho angle of support. This pull releases the safoty clevieo and allows the pilot to pull tho l[1nyard down, relm,,sing himself from the glider. The pilot can pull oither left or right depending on which side he insorts the pin. The tota.J release t.ime a fnwtion of a second. Our entire weighing Jess than pound and adjustable in length, attached t,o the glider through the triimgle bar or around the tube by a 2-,inchwide nylon webbing. Total strength rated a.t 4,000 pounds. triangle \ilock attaehes webbed or lrnrnesses wider than inches. This produced from military panichute parts, stainless stoel and nylon webbing, and is put into shape by an experienced pa,rachute Jt, wi lJ fit ciny glider or lrnrness, The safety elev ice insures that the cannot be nctua.ted irrndvortantly in any attitude, yet providos the pilot with an instantanlous from his wing in an emergency condition or upon normal landing. No more agonizing seoonds underwater fumbling for ring hanging in tree waiting for to come iwd extricate you. No more broken wing tips side with you hanging in the sea,t,orha.rness. more flying with a release Urnt nrny launoh you into fall at an unsuspeeting rnoment. W.lth this new system you have the security of a "D" ring with the versatility of a quiek relciase nrnchanism. This new release system is a.vailablo for $l3,H5 plns 50¢ handling and postage from Wings For Man Hang Glider J<;mporium, Box Islip, NY H'7cl0,

ROPE HARNESS

l'EBRlJARY, 1975

NANG GLIDING

Flight Simulator

fut r1 f!JN

WintPr··PVf'llfng's project

Reali,,ti, l/6 "al<' model Rog,dlo hang gli,kr with rolorlul polyvi11YI !Lhive weight llO\dlr,,11111,1 ..,ystPir1 dnd ddju'.:ltable *I 1d!Px p<'11nit, mod,,! lo duplicdt<' the flighl

chtitdl IPric,tic s ,ltld

k1H'. l<it < ontains dll p.irh di HJ

Your instructor will be with you at all during your first

above sand. It's

DEALER INQUIRIES INVITED

All you need for indicator s a thn}e 11-6 model

L Disassem.ble odometer Reassemble.

bracket

and re1nove to reduce shaft friction.

Cut small

props as shown. Sand. of :y,1" dowelL off the head of al and file shank square to fit

included

with

hole in center of dowel and screw. Put dab of epoxy on square end and insert into After

to

b

d 0

1

Draw a cardboard

as a rotor.

m carve away

flower" on when

After use covered dowel to smooth a fit.

make

213

HBIUJARY,

All supplil's 011 stock cc1t-1log '.l,1.00 rdundablc II rock c;ll.ilog $2.00 rd Ui1(lc1ble

ION 44141 860 Jpffe>rsor1 Ave. CIPvel.111d, Ohio 44lll (216) 861 b72B

by Wilson B,lker

Detailed m,qv; of each

IOCdlion.

Con1p!cte flying in<il! 11ctlon~.

"lhc hook for expvtt ,md novicL' pilot ,dike.

Original artwork by Jt~,tncttc Bo~tick.

CIILCI< OR

SEND

ro·

ORDlR

II SOIIRINl, ASSOCIATION llOX 261

SONOII II, ARI/ONA

period! Unfortunately, instruction will contribute undorsta,nd i ng ... oeoasi on al

1111

I FLY: rrnE COMPLHJTB BOOK OF'

Carrier. McGraw

SAILING, by

Hill Boo!, Company.

After many delays, Hic)k Carrier's book Tl1e Complote .Book of S'l<y Sailing has finally hit the bookstores. Actually, the fault for the long wait lies neither with Carrier nor book's publisher, McGraw,Hill. Jt, that the originally sub.contracted printer blew it, the whole thing had to reprinted.

Those that Llw book would be dated hy the time relea,sed at least, partially in his appendix, for instance, that interested parties contact the 800 member Southern California, Hnng; Glider Association.

Dated deta,ils don't generaHy destro,y usefulnoss ... and they don't in the of f?Jy, either. The ca,sual reader will much that current and useful. Tllo book's major failing, rather, is in army of misinformation.

Readers wlll be surprised to find, instance, tlmt spoilcrs ... "concentrate the flow of over prevent stalls when nrnking· turns." Equally surpri£ilng "fact'' that the Quick1,ilver',, rudder ... yawing during turning maneuvers." Quite Carrier's ch,im that standard rogrd.lo's best "ls to Hl mph and wi 11 stall about 9 mph." Do pending on yonr point of view, you may either ngree with, or violently object to calling hybrids "Bttstard Sky " Carrier asserts tlrnt "Urn mos I; common cause of sky i,cciclents hwk of understanding oI Urn belrnvlor of the Perlutps it would lrnve been better wordod, "the most cmnmon cause oJ sky sailing accidents of understa,nding"

]O

little

of the tho contribut,ing

treatment oJ sketelly; his offhand Photos used one point handling inciisting;ulshablc from those show la,unch." day where safety such an inoreclibly importanL part nnr sport. it is vita.I tlrn.t the equipmellt, but also the tl:rnt

unfortm1,Lely, sLill '"'"'·'·,11111,, popular With broader availability, format,

by Poynter and instn1ctiomtl ma1uml.

For this sock out one of today's out1:Jta,nding lrn,trLwtors The there for a tremendous tx;aining photos are reminiscent Richard W1"1Her:,i" Art 11,11d Teelmiqtw ai1;ra,ettvr3; the basic format

truly eomplete hook which, lHlOW for

sailing. ".t,.

M,uk Lang;,9nJctd

INSTRUCTION

11)74 Bulldlng

Chris A. wm1 The

lJigller the perlon1m1we tlw lmtt.er. Higllt? Not necessarily. Chris Wi /ls brings up some import.ant points you slum ld consider /Jeloro modifying

your kit.e.

Inherent pitch stability in any c1ircral't design is one of the most important aud safety.determining of that design. In rigid wing· a.ircraft there a.n abundance of infornrnUon avai !able to anyone who wishes to read up on the subject. In flexible wing· aircraft such Rogallo kites, this is simply not the case.

Inherent pitch stability in 1,ny ontirely 'new' type of aircraft may bo predicted to a eertain extent, but only actual testing will determine if tho predictions aro correct.

In most casos, inhonm1, stability will actually reduce performance to some extent, but it of pf.ramount importance if a design is to prove safe. ln fixed wing aircraft, piLch sta.bility is accomplished by pla,c:ing Lim center of gravity ahead of tho center of lift ,md eompensating for this by giving an upward tilt in the lwrizont,Ll stabilizer.

lift

This gives the airplane a tondency to straight and level in 1.lw foll owing way: Since gravity is constn,nt force, it will always aot the same regardless of airspeed. Tho np a.rd tilt of tho horhmntal stabilizer, on tho other hand, such that the force it exerts will increase witlt airspeed. At the predetermined inherent stability airspeed, these forces will eounterbalance ea.eh other so that the speed is maintained. If the a.irspeed is

32

slowed, however, I.he elevator force of the tail will decrease while the gravity force will remuin the This will cause ttw nose to drop and the ai.rplmm wi II gain speed until theformis again balance. If the airspood incroased. the e lovator foree will inerease while the gravity force will ag·ain ronrnin constant. This will en.use the nose to until Urn in balance. In this way tho airplane will always want to return to the stable equilibrium (tcclrniea.lly called 11 convergent equilibrium). lt is inherently pitch stable.

In a Hogallo flexible wing aircraft similar type of pitch stabilit,y ma,y be aehh'lved in an anal ago us nrn.nnor. In this ease the center of gavity pliwed by the pilot's weight. 'I'his somewlrnt more difficult, however, since wind resistance by the pilot's body tends to move the weight backwards, but oxeept for fine tuning, this effect can be Jniti11lly ignored.

Since there no tail surfaces on a Roga.llo kite, may at first seem impossible to an upward force to counter the down ward of gravity.

Keel rel'lex it turns out the key factor that iwts a.s this balancing force although it works in a much different manner.

The way keel reflex works is very complex and is related to the shn,pe of the floxible fabric 11.t normal angles of attack, and to the Jack of shape of the fa.brio at extremel,y low angles of attack. Basioal ly, keel reflex cu.uses the rear oi' the s,dl to produce lmrn lift than the froni, of the sail (that's right,it destrnys lift!). Since ii.ft a function of speed, this more pronouneed at hig·h speeds thus eamiing a net force at higher speeds. At very speeds, the onset of flapping at the rear of Um sail will dei,troy the lift

entirely, Urns the effect will be more pronounced. dogleg or camher .into the sai I wi.J I counl,m· it mnst be taken into a.ceount when figuring reflex.

F'or kite nrny be thought of slightly upward bond Uw nrn,y be follows: pictured

By pl acing tho center of gravity front of the center lift mid Jrnving proper amount counterbalaneing reflex, pitch stability be which works exactly llko the case of the airplane.

Thero one other force acting on Rogallo kites that not present to an appreciable extent in fixed wing stabil.ity design. This the pondul um··likc foree acting between the weigl1t (the pilot) and Urn lifting surfaee (tile kite). Since gnwity acts to pull the person down wbile lift acts to pull kite up, an equilibrium achieved which to lrnep the kite righted and flying level. Dra,g on Uw kite also than it on the person, thus, if the dropped, the resulting torque will act to sta,bilizc the kite as tho speed innr,roa:~01~.

Ff:BIUJARY, '197.5

will

the speed

increased:

Throughout this discu by tlrn pilot, inhenmt stn.bi Iit.y should control of

Urn

up. The noga.ti Uw lift. at. the rea.r of I.hat of t.Jrn front of the up. Both of force which is relatively if slowed below tllis stable speed, Ltll three Urn kite up to that spood.

CfUI

horizontal stabilizer at tilted up, or by mcclrnnic,dly the pilot's control.

Jn working· with

tho increa.sod 11 large amount of unstable equi ii bri um Uw

that the negative

Uw roar to be tighter Umn the front,.

the flapping will occur in front it. will in lmck.

1i rt destroyed in front, divo will be greatly th is point Uw nega,tive

produces a. ti12;lltor the front show

override 1.lrn negative reflex complete dive not show any Londeney to steep dive, then, n.nd only th.en sltould be ftown without such a

from the Where applicable, aissume that a "standard" Hogallo has rm apex angle of 80° to 86° and a wing-loading factor of J .0.

Northwest

Glider

generally be slow, normal. or irn~nrn~md t:3. Should air for initiating turn'?

A. increa:seti.

1. State the formnla for determining wing,lmtding.

Wing-loading

What is the best winri;.loading factor of a st<rndasd Hor~allo in: (a) Light winds (0·10 mph) (b) Medium winds (10·15 mph) (c) Heiwy winds (15 mph plus)

How docs tomporature The w,1rmer the air, the lower of sink and higher air spoed.

rate

hence

16. How does elevation affect hang; D"hidino·'I A. The higher the altitude, the thinner tile air. which results in an increased rate of and higher a.ir speed.

A:

rn. In relation to the horizon, in wlrnt position should your cross bn.r bo during normal ta.lrn-offs and landings?

Level.

(a) .8

(b) l.O (c) L2

State the approximate air speeds of a standard Hogallo under the following· conditions: (a) Take off (b) Stall (c) Maximum safe speed (a) .15 to 20 mph

(b) O to 14 mph to 65 mph

(c)

4. State the approximate glide ratio of A. 4 to 1

standard Hogallo.

Should air speed be fast m· slow wllen approaching for landing'!

A. Generally, air speed should be fa.st enough to allow for complete control.

6. In winds, what should one do with tlrn nose of the kite immediately upon landing'?

A. Put nose on the ground facing· direetly into the wind.

7. In a northwest wind, what direction should one be facing during takeoffs ,md landings?

Northwest.

State the first prerequisite for flying on private property.

A. Obtain permission from t.hc land owner.

Wbat might a "loud" flap 1 flight indicate?

High airspeed (a. potenLially dan12;emus condition maintained), or misfitting 18. State the result of the contrnl har touching the ground at flying speeds.

A. Usually the kite will nose in abruptly causing the pilot's body to swing forward and hit Hitlrnr the control bar or the kHel bar with Hnough force to cause injury, broken shouldHrs, ciollar bones, and heads. KEIDP TBJ~ CONTROL BAR OFF THE GROUND TIMJ;JS WHILE YOU AHJiJ MOVING FOHWAHD!

What wind conditions dangerous to hang· glider flying?

Gusts of more than 1.0 mph, or winds greater than those in which aeeustomed to NEVJDH IN WINDS Tl-JAN THE FLYING SPimD FOH YOUH HANG GLIDER

20. Whitt a stall'? laek, or a loss, of airspeed which results in a dang·orous rate of sink. .. you fall!

What is an accelerated stall'?

A. stall at higher than normal air an abrupt flair attcrnpt.

such

10. List checkpoints immediately prior to takeoff.

Chee!{ harness or seat, wind direction, clear flight rmth, cleiu landing a,rea. i 1. State the chief cause of lrnng glider accidents.

A. Pi.lot error.

12. State smne of the hazards of a downwind la.nding.

A. Greatly increased ground speed, increased sink rate, dang·er of stumbling and being flipped qver upon touchdown.

34

turn or

How do you recover from

A. Nose the kite DOWN until sufficient air 9. List checkpoints of Rogallo prior to buckling in.

A. Cheek all nuts for tightness, cables should all be tight, unfrayed and in order, sail should be tied down eorrecUy, and harness or swing se,tt should be securely attached. Looi{ everything over and g;ive it a good shake .. .it's your life.

in

gained to

resume normal flight somo indications of 2:3. Wlrnt Very little wind against.your sail.

Who the experienced world?

Birds ... watch them closely, they can teach you a great deal.

What specifications of aluminum tubing are recommended for ultra-light frames? (two f{rados) 2024-T3, 6061-TH 26. Explain the properties of T3 and TO specifieations.

T·3 , highyiHld point (bending point) high maximum load (breakage point) (Continued)

I

IN

I

AND

L

in.

in

with

UL

LY NG MACHIN California 95014 Phone: (408)

ID

T-6 less high yield point (more and easier to bend than ·rs) high maximum 101,d (will hrea,k than T3).

No.

2024

Yield (psi)

0

'I'--:.l 6061

7075

()

10,000 :37,000 (j(),000 U,000 50,000 47,000 8,000 21,000 40,000 15,000 73,000

25,000 61,000 68,000 27,000 70,000 fi8,000 18,000

~m.ooo ()

'f .. fl

Explain the properties of (a) alloy designations.

45,000 33,000 8:J,000

and (h) ()0131 aluminum

(a) Copper based alloy; hi.gh strength, excellent fatigue resistance, easily machined, difficult to weld, poor corrosion

(b.) Magnesium and silicon based alloy; least expensive 1.md most versatile ol' the beat treatable alloys. Good strength, worked and weldable.

What rnin.imum grade bolt recommended for ultra-light a.ireraft?

Grade grade AN (aircraft bolts).

FLIGHT REALITIES Avenue

CA 92116

298,1962

Why should tubing bolt points'?

F'or additional strength. the stresses are transmitted the kite at such points. :30. Approximately how muell tube, inch O.D., 130131.-T6, weakened by drilling a inch hole through the tube?

By approximately 50'!1,.

How often should an be completely disassembled for inspection of possible worn damaged components?

Twice per year; more frequent inspcetion recommended if the kite used two times per week or more; or following any

COLVER SOARING INSTRUM NTS 3076 ROANOKE LAN

COSTA

CALI

Quantity Discounts Availabl Calif. r<Uidc,nU add 6°/o u,lu la

What is "pendulum stability" and what effect does lowering the pilot weight (lowering; the ecntHr of gravity) have on stability of the kite?

A. Pendulum stability the of an object to stabilize itself in a ceri.11,in oriental.ion because of the pendulum force exerted by having the of gravity of the object below its fuicrum point (roughly the levol of the crossbar). Lowering pilot weight (CG) increases pendulum stability and the tendency hang glider to right itself (stabilize itself in nornrnl flying oricnta.tlon) Thus, lowor CG might be advisable whon flying in turbulent oonc!itions.

As:suming that the what effoct does lowering the pilot ,Lt.t,whmcnt point on the /\-frame have control resp,m:1sE,'!

A. Lessens effoctivc weight elumge control; a.nd slower response of hang glider and more effort genorally needed for Lhe rosponse obtainod.

the trailing CREATIVE SCULPTURE$ c/o Hal.l, Madisonville, Te:nncrns13e 37354

of ,1 srdl which

What leoch'!

Thtl amount of conical billow in !.he trailing ,i.xpressed in inchos.

What camhor'?

The curve line over the top of

of a sail

sail from fore to aft.

(Continued)

buy.

Wi11gs1

with When would you hang gHdor'?

A. Direotly behind at same

downward

probahlo effeot

what position by tho other sllghtly highor lffvoL

flight of ti Hogallo with negative pitohing moment

:rn. Wbat

tip stall, and how it be avoided'? of lift of one wing tip while turning, n1a.intaining adequate when turning, Why is flying a mountain beach Mountain air usually generaJl,V more hazardous.

The amount of in cut on tlw trailing edge of one wing of a lying fla,t.

40. Why a king post recommended on Rogallo'i' To the hang glider for neg,ttive preserve the struetural integrity of the hang glider in event of crashes while on the ground in high winds. standard Rogallo in no-wind condition, approximately how many feet of aUitude needed to stall'?

40 feet for a normal sta.11, up to 200 feet plus fot· a radical stall.

1nore ha,zardous than flying stable,

4f3. In what proportion does force

turbulent,

with

with the of the velocity. Thus, the in a 20 mph wi.nd 4 times that exerted 10 wind, 9 tilnos greater ::io mph wind than in 10 mph wind, and 16 times greater in 40 mph wind than in .10 mph

calm air, what When flying frorn a 2,000 foot-high hill in conditions would likely be found: (a) dry, dark patches of earth? (h) Over small (e) Over (d) Directly under cumulus clouds? (o) Somewhat the aroadirectly under cumulus clouds'?

Thermal (b) Norornl (c) (d) Thenmtl J

possibly quite strong. (e) Thermal downdrans.

1321 Calle Valle (unit Fl,

Clemente· California

(114) 492,0670

Mernber

114J N.

I

R Admission

-- ---

I I I I I Narne I

Num

--------------------------1I

Qualification Mail Check or Mon

o Id, 3901.

cu ston color (21:3) 943 10'74. Call a.Her 4:00.

postpaid. Vinyl··Coated itc(l foot)and SI ip 011 or Button control bar Long Island Bethpage Hoad, . (fiHJ) G81-87:.l8.

IN TJ-rnru,:, $fl/yr. oao1 Hichficld, MN

ing

to with

9006G.

, Freelnnd, Mich.

Calif. HOG:!L (21:3) visit, and our 1,: i pper ·l"ormance and other equipment. th rough Friday, 10-fl

1Jang Gliding, of Urn sport by Dan Poynter, (Add .fiO for airmail.) Man l'owernd F.ligllt Keith $6.50. Hang Flight., instructional manual, Simplified Performance Testing /'orllHng by ,la.ck $g.oo. ALL

postpaid

Box G6:30fl, CaliL DOOfm.

Urn

i struction.

Marlboro, me.

Dan Pea.rco

1975 HANG GL[I)JNG CAU;NDAH, full-page black-&-white photographs, easy-to-read ealenditr format must for every ultralight flight enthusiast! $1 postpaid. M11kes good gifts. Order from USHGA, Box mi306, fJ0066,

UNIVERSAL HANG! ,IDfNG ,,,, , '""'""· Jiang.lider Shoppe, rn[i4 Fifth l8(l0-GS, Sa,nta Monica, CaJiL 395-4991,

C,mada.

Seminar" held in ,Jammry, Northrop Institute or Teelrnology, complete Ma.ko payable to tho A!AA Student Branch, c/o NJT, 1lb5 W. Arbor Vit,10 St., Inglewood, C,tliL 9030G.

SOARING sailplane with eovorage. Ava.iln.ble with membership, (Me1nber, $1:5; Associate member, $9/yr.)

Info kit with rmmple copy, $1. Sc:1,uinir, Society of 66071-G, Angeles, CaliL 9000G.

USIIGA emblems, diameter, full-color-$L Decals, dia., inside outside application, l nclude l 0¢ for postage and handling with each order.

Box 66306, Ca.lit 9000H.

Ma.in Winter Hang u11cting Championships Fly,In at Mt. Abrams. Competition for pilots. Hele!. Held in conjunction Bethel's Winter ivaL l<'or informa,tion, contaet Jot; Hobiller, ML Loclnnills, Maine.

March Ultralight Fltg'l1t Northrop Jnstitul.o of Teolrnology. Attn: Prof. Paul Lord, 1155 W. Arbor Vitae Inglewood, Cn.lif. 9030G. March

World Championships in Kite li'lying. F'or information, WOK·Offiee, Austria. Te.le phone: rn,:376/ ~176,

OR STANDARDS