NO METAL FORMYRON

Myron Jenkins' all composite GlaStarJACK Cox

X

I yron J e n k i n s of Parker ,Arizona, is a world-classbuilder of composite

homebui l t s . In 1985 he com-pleted a 160-hp Glasair RG thatwon awards everywhere he dis-played i t , but he rea l ly hi t thejackpot with his second project, aGlasair III he completed in 1991.That fall, in its first outing, thea i r p l a n e was the a l l -ca tegoryGrand Champion at the Copper-state EAA F l y - I n at Prescott ,

24 NOVEMBER 2000

Arizona, and the Grand Cham-pion Homebuilt at the SouthwestEAA Fly-In at Kerrville, Texas, acouple of weeks later.

In March 1992 the Glasa i r IIIwas the Best Homebuilt at the AAACactus Fly-In at Casa Grande, Ari-zona, and the Grand ChampionHomebui l t and Great GrandChampion at Sun 'n Fun '92(which earned Myron the coverand a feature ar t ic le in the June1992 Sport Aviation). Completing

the grand slam, the airplane wasthe Grand Champion Homebuiltat the 1992 Northwest EAA Fly-Inat A r l i n g t o n , Washington , andGrand Champion Custom Built—Kit at EAA AirVenture Oshkosh.

Obviously, Myron is a big fanof the various Stoddard-Hamiltonhomebuilt designs. Even thoughit was virtually a 180-degree de-par ture f rom the company'sprevious low-wing models, whenthe August 1994 Sport Aviation in-

troduced the GlaStar, Myron wasimmedia te ly a t t rac ted to thehigh-wing, strut-braced Stoddard-Hamilton design.

He did have one big hang-up,however.

The Glasairs were the pioneersin molded composite construction,but the GlaStar was someth ingquite d i f f e ren t . It had a moldedfuselage shell typical of many com-posite designs, but it incorporateda welded steel-tube cage inside

the f ront half that served as theload-bearing structure for the en-gine, l and ing gear, and wings.That Myron could live wi th , buthe drew the line when it came tothe GlaStar 's riveted a l u m i n u mwings, rudder, and horizontal tail.

"I just don't like pounding riv-ets," he says. "I don't t h ink 1 couldmeet my own standards workingon a metal airplane. 1 like compos-ites. I like to work with fiberglass,and I'm used to having an aerody-

namica l ly clean, Glasair-type air-plane. 1 liked everything about theGlaStar except the m e t a l w i n g sand t a i l , so I f i g u r e d tha t if 1wanted one 1 would have to buildit entirely out of composites."

R a t h e r t h a n t r y i n g to reengi-neer new wings, Myron decidedto simply duplicate the a luminumparts using carbon fiber and fiber-glass. The project began when hehad the opportunity to examine aGlaStar wing and measure the vari-ous parts and components. Thenext step was to make molds, thenlay up parts in them. He used thesame Hercules carbon fiber cloththat went into the primary struc-ture of the globe-girdling Voyagerto build his spars and skins . Hemade his ribs out of fiberglass andused Stoddard-Hamilton's low tox-icity vinylester resin throughout.

Early on, Myron made the Stod-dard-Hamilton management teamaware of his intentions, but henever felt they were taking him se-r iously , u n t i l he showed up atOshkosh one year w i t h his con-s t ruc t ion photo a lbum and somesample parts he'd made. They weresuitably impressed with his excel-lent w o r k m a n s h i p — c e r t a i n l y nosurprise considering all the GrandC h a m p i o n t roph ies he had wonw i t h his Glasa i r s . But they weres t i l l ama/.ed that anyone would goto all the trouble of making moldstor essentially every part in theGlaStar's wings, ailerons, (laps, thehori/.ontal stabilizer, the elevator,and the rudder—not to mentionmaking the parts himself!

Myron says fe l low G l a s a i rbuilder, Roger Heisdorffer, of Tay-lor, Arizona, was a valuable mentorto him as he broke new ground insubs t i tu t ing composites for alu-m i n u m . At the t ime , Roger wasalso building a GlaStar with thestandard metal wings and tail, andhe provided a lot of technical in-sight and encouragement.

After making the wing and tailspars and ribs, all identical to theirmetal counterparts except for

Sport Aviation 25

Modeled after hisaward-winning GlasairIII, Myron againInstalled an all-leatherinterior including aleather-coveredinstrument panel.

wider flanges for bonding, Myronbegan laying out his exterior skinson a 15-foot-by-30-inch glass-topped work table he'd built yearsago for building his Glasairs. EachGlaStar skin consisted of two lay-ers of carbon fiber, with the weavesoriented 45 degrees to the other.To attain the correct shape and toavoid excessive bending of the flatskins, he made molds to form theleading edge skins.

Myron used the space betweenhis main and rear spars to createfuel tanks, sealing the voids inmuch the same manner as in hisearlier Glasair wings. Ultimately,he would f ind he had room for atotal of 65 gallons, all very nearthe airplane's center of gravity.

The standard GlaStar has Friseailerons, but choosing to avoidthe wide gaps common to thattype, Myron employed the samepiano hinge at tachment used inthe Glasairs. This change presentedthe problem of how much differ-ential (up/down) action to use toreduce adverse yaw. After consult-ing with Roger Heisdorffer, Myronbuilt up his own bell crank actua-tor mounting plate with a series ofholes that allowed him to change

the aileron differential. Roger's ad-vice was to start with a 2-to-l ratioand then make changes as needed.

Closing the wings was a "tick-l ish" process, Myron recalls. Itinvolved applying seemingly end-less smears of resin on the ribf langes and then wres t l ing thelarge, floppy skins in place. Heclamped the trailing edges betweenlong bars of a l u m i n u m to keepthem straight and used weights tokeep the sk ins t i g h t l y pressedagainst the ribs and spar caps untilthe resin cured.

After completing the wings, My-ron built a mounting fixture and,using data from Stoddard-Hamil-ton, proceeded to load test them.Both easily withstood the load, butwith the same load Myron's com-posite wings deflected 8 incheswhile the factory prototype's metalwing deflected 6 inches. To My-ron's great satisfaction, his wingpanels came out weighing about18 pounds less than the standardaluminum wings, even with thesuper smooth, ripple-free finish hecan't stand to be without on hisairplanes. He buil t the GlaStar'shorizontal tai l and rudder in es-sentially the same manner as the

wings, with piano hinges to attachthe elevators.

With his wings and tail surfaceswell under way, Myron ordered atri-gear GlaStar fuselage from Stod-dard-Hamilton. Built in standardform, it readily accepted his com-posite wings and tail because allthe attach points were identical tothose in the metal versions.

Myron ventured out on his ownagain when he selected an engine.A 125-hp Continental IO-240 pow-ered the prototype GlaStar, whichlater received a 150-hp Lycoming.Myron moved even farther up thepower scale, ins ta l l ing a 200-hpLycoming IO-360 in his airplane.An experienced engine bui lderlong before get t ing into home-builts, he'd rebuilt the engines inboth his Glasairs—and did so againfor his GlaStar. He bought a 160-hour engine f rom a wreckedairplane, tore it completely down,and rebuilt it using higher com-pression pistons and "chromingeverything I could."

The engine had a front-mountedfuel injector unit, and Myron madehis own intake for it in an effort toget some additional ram air boost.To better cope with Arizona's sum-

26 NOVEMBER 2000

Myron duplicated thealuminum parts of theQlaStar using carbonfiber and fiberglass.Each wing skin was

built up from two layersof carbon fiber with the

weaves oriented 45degrees to the other.

mer temperatures, he installed anoversize oil cooler and ran twoduct hoses to it. ioward the end ofthe project, he had Margie Warnkebuild a wood prop for the airplane,s i m i l a r to the Almos t ConstantSpeed prop her late lather built forMyron's Cilasair KG in the 1980s.

With the major airframe andengine work behind him, Myronwas able to begin what is for himthe fun part of a homebui l t proj-e c t — t u r n i n g h i s c r e a t i v e sideloose on all the fancy stuff . Stuffl ike a lu l l - lea ther interior, under-seat tool boxes, a custom,leather-covered instrument panelmodeled a f t e r the one in hisaward-winning Glasair 111, and anengine cowl with no visiblescrews, hinges, or fasteners. Healso ins ta l led his own spr ing-loaded rudder and aileron t r imsystems, as well as an electricalflap actuator.

Myron has always had a self-confessed need for speed, and hisgoal from the start of his GlaStarproject was to end up wi th thefastest example of the type in ex-istence. That was one of thep r i m a r y reasons he decided tobuild aerodynamically clean com-

posite wings, and it led to someintensive fa i r ing work. This wasespecially tricky at the ends of thewing struts because the fa i r ingshad to be capable of sliding awayfrom the intersections to allowthe wings to fold.

The paint job and tr im schemeduplicates the one on Myron's GlasairTil, and i ts u n d e r s t a t e d eleganceworks just as wel l on the CilaStar.However, Myron says he likes thewild trim schemes the new multi-glitter paints now make possible,and if he had it to do over, he'dhire a professional to make the air-plane a real mind bender.

It took Myron about two-and-a-ha l f years to complete hisGlaStar, dividing his constructiontime between the family cabanathat overlooks the Colorado Riverin what passes for w in t e r thereand their Arizona mountain cabind u r i n g t he summer months .Other bu i lde r s con t inue to beamazed t h a t Myron pa in t s h ishomebuilts in the open (on hiscabana) in the no rma l ly dus tydesert air. There's no mystery toit, however. The desert dust is ex-tremely f i n e in texture , and hesimply sands and buf f s it out of

the surface layer of paint.When f i n a l l y ready to fly in No-

vember 1999, the (i laStar tippedthe scales with a 1,261-poundempty weight. That, Myron feels,compares quite favorably with theweights of other ( i laStars he's fa-m i l i a r w i t h t h a t have s m a l l e r ,l ighter engines.

At Sun 'n l;un 2000, the airplane'sfirst major public appearance, theGlaStar cruised at 175 mph at 2550rpm and 9.5 to 10 gph. That wasw i t h a prop tha t needed a l i t t l emore p i t c h , so he's h o p i n g formore speed when the 2000 fly-inseason is over and he has a littlemore bite carved into it. L igh t l yloaded, the airplane's init ial rate ofclimb is around 2,000 fpm, and itcan sustain 1,000 fpm for quite awhile at maximum gross weight.Fortunately, the 2-to-l aileron dif-ferential Myron in i t i a l ly dialed inturned out to be right on the mark.

Just one s igni f icant problemsurfaced when Myron began fly-ing his GlaStar . The enginealways fired right up, but it "did-n't sound right" at cruise andwouldn' t idle at less than 1100rpm—which made landings quitean adventure in so clean an air-

Sport Aviation 27

•

plane. Myron tried all sorts ofadjustments, all to no avail, andf i n a l l y called Lycoming for ad-vice. A mechanic there listenedlo his tale of woe and immedi-ately diagnosed the problem as aleaky intake manifold.

Following the mechanic's in-structions, Myron plugged f n e

host1 from the out le t side of hisvacuum cleaner i n t o the injectori n l e t to pressuri/.e the mani fo ld ,and then he began pouring soapywater around all the O-ringcdconnections. Sure enough, one ofthem started b lowing bubbles ,which led to the discovery thathe'd crimped and cut through anO-r ing when assembling the en-gine after its overhaul. When hereplaced the O-ring, the engineidled perfect ly at 650 rpm andran smoothly throughout its rpmrange. Myron adv i ses f e l l o whomebuilders to check those O-rings if they're having a similarproblem and to be very carefulwhen installing new ones.

A quest ion t h a t had to beasked was how Myron was cop-ing w i t h s t epp ing out of a f i r e -b r e a t h i n g hot rod l ike a GlasairIII and into a docile little all-pur-pose Spor tp l ane like a GlaStar—even with 200 hp in the nose.Quite well, it turns out. Myronsays he finds it to be more stablet h a n the G la sa i r s , and at 175mph it's still a very capable cross-country Mi rp lane , especially wi thits generous f u e l capacity. All oft ha t , however, pa les i n t o i n -significance when we learn themain reason he is pleased wi ththe airplane.

"My wife, Marie, loves it, andthat's a big plus. She's never beencomfortable with the high land-ing speed of our Glasair III, so shethinks the GlaStar is great. That'swhy she flew with me to Sun 'nFun this year. She wouldn't havecome with me in the III."

Slow(er) can be beautiful, guys,

Myron JenkinsMyron Jenkins Is a trans-

planted lowan. He grew up inthe Hawkeye State in the1920s and 1930s, but he lefthome in the early 1940s toserve his country duringWorld War II. Afterward, hesettled in Los Angeles andstarted a business that man-ufactured and installedmarine electrical equipment.It was so successful he wasable to retire at 45. He andhis wife, Marie, moved toParker, Arizona, and havebeen living there ever since—except for the summermonths when they opt for thecooler temperatures at theirmountain cabin.

Always interested in flying,Myron finally got around totaking flying lessons in theearly 1980s and soloed inboth a Cessna 152 and 172.He stopped flying when he be-gan building his Glasair RG,but he obtained his privatecertificate in the airplane af-ter it was completed. Aninnovator and a true crafts-man, all three of Myron'shomebuilts have been multi-ple trophy winners.

Sport Aviation 29