OX-5 Pow­ered WACO 9


It could be ar­gued that a ma­jor fac­tor in the birth of civil­ian avi­a­tion was the Cur­tiss OX-5, 90hp, liq­uid-cooled V-8 en­gine. That wasn’t be­cause it was such a won­der­ful en­gine. In fact, it was heavy for its power and crude in ev­ery de­sign de­tail, and it took some tin­ker­ing to keep it run­ning. Re­li­a­bil­ity wasn’t its strong suit. Pi­lots of the day, many of whom were barn­storm­ing from farm fields, said that they flew OX-5s from emer­gency land­ing to emer­gency land­ing. It was the seed of 1920s’ avi­a­tion sim­ply be­cause thou­sands were avail­able on the mil­i­tary-sur­plus mar­ket for next to noth­ing at a time when air­craft man­u­fac­tur­ing was in its in­fancy.

How avail­able was the en­gine? It was de­signed and built by Glenn Cur­tiss and com­pany for the orig­i­nal JN se­ries, cul­mi­nat­ing in the JN-4 “Jenny” in 1915. By 1919, Cur­tiss had built more than 6,800 Jen­nys, with ap­prox­i­mately two en­gines for ev­ery air­plane. The Jenny and the sur­plus en­gines were the back­bone of 1920s’ barn­storm­ing, and the OX-5 en­gine pow­ered many new de­signs. Iconic avi­a­tion com­pa­nies, such as WACO (Weaver Air­craft Com­pany), Travel Air, and many oth­ers, all of which were work­ing on shoe­string bud­gets, got their start build­ing af­ford­able air­planes around that en­gine.

WACO, which be­gan busi­ness un­der the ban­ner of Ad­vance Air­craft Com­pany and was re­named in 1929, fielded its first mass-pro­duc­tion air­plane as the OX-pow­ered WACO 9 in 1925. In the best WW I Fokker D.VII fash­ion, it had a welded tube and fab­ric fuse­lage, with the wing struc­ture be­ing rag-cov­ered wood. The slow­turn­ing (1,400rpm) OX-5 swung a big 8-foot-plus prop, which, only hav­ing 90hp to work with, pro­duced enough thrust—barely! Com­bined with the nearly 30-foot wing pan­els and light wing load­ing (1,320 pounds empty;

2,100 pounds gross), the WACO 9 could haul a pi­lot and two pas­sen­gers out of a wheat field—barely!

By the mid-1920s, the OX-5’s days were se­verely

num­bered. It had es­tab­lished the avi­a­tion mar­ket as be­ing a vi­able source of rev­enue, so a num­ber of com­pa­nies, in­clud­ing Pratt & Whit­ney and Wright, were formed to man­u­fac­ture ra­dial en­gines that pro­duced two and three times the horse­power for the same weight. Equally as im­por­tant, the new en­gines didn’t have the ir­ri­tat­ing habit of de­posit­ing pi­lots in re­mote fields or in the trees when they quit. Still, ap­prox­i­mately 270 OX-pow­ered WACO 9s were built be­fore the WACO 10 su­per­seded it, of which an in­cred­i­ble 1,600 were built. Only the first WACO 10s were pow­ered by OX-5s. Pro­duc­tion had barely be­gun be­fore they were re­placed by Wright J-5s and sim­i­lar, now-leg­endary, ra­di­als. Gen­eral avi­a­tion now had re­li­a­bil­ity on its side.

Only a small num­ber of OX-5 pow­ered air­craft of any kind still ply the air­ways. Most are Jen­nys, but a few WACOs still sport the won­der­fully stream­lined nose that cleaves the air aside, let­ting the usu­ally blunt OX-5 through. One is WACO 9, NC1536, owned by Scott Glover as part of his pri­vate col­lec­tion, Mid Amer­ica Flight Mu­seum in Mt. Pleas­ant, Texas. As se­rial num­ber 9, it is one of the very first air­craft to be built by Ad­vance Air­craft/WACO. It is also flown reg­u­larly, of­ten with Kelly Ma­hon at the con­trols.

Kelly says, “This air­plane was orig­i­nally re­stored by Frank Pavliga. He started with a fuse­lage and three wings that were good only for pat­terns. It is es­sen­tially a new air­plane. But it is a true antique in ev­ery way. It has no nor­mal air­speed in­di­ca­tor, no brakes, a tail­skid, no carb heat, only one mag, a rud­der bar rather than ped­als, and on and on. The way it han­dles in the air is pretty well summed up by a line in the hand­writ­ten pi­lot’s hand­book that says, ‘The ailerons are only a sug­ges­tion to the air­plane.’ It is leisurely in the ex­treme.

“Me­chan­i­cally,” he con­tin­ues, “it is, shall we say, ‘unique.’ Rig­ging the wings, for in­stance has more to do with the phases of the moon than an­gles and mea­sure­ments. The en­gine has to be con­stantly mon­i­tored and pam­pered. The valve train has no in­ter­nal lu­bri­ca­tion, so we grease it ev­ery day or ev­ery 45 min­utes of flight time. You can see the rocker arms jig­gling around out there while they are throw­ing grease back over the air­plane. It cruises at 65mph while turn­ing 1200rpm.”

NC1536 keeps com­pany in Glover’s mu­seum by air­craft that show how quickly air­frame de­sign pro­gressed in the ’20s and ’30s. They in­clude the first DC-3 taken into the U.S. Army Air Corps (a heav­ily doc­u­mented C-41), a Mus­tang, a Cor­sair, an A-26, a Grum­man Duck that sur­vived Pearl Har­bor, and a wide va­ri­ety of other his­toric air­craft.

The WACO 9, how­ever, shouldn’t be den­i­grated for its short­com­ings. It was a pi­o­neer in the birth of civil avi­a­tion and was in pro­duc­tion only seven years af­ter the end of WW I, a time when civil­ian aero de­sign and man­u­fac­tur­ing were just get­ting on their feet. Given its his­tor­i­cal im­por­tance, it’s a won­der­ful thing to see one of the breed still in its ele­ment.

Above: The WACO 9 used an abun­dance of wing area to make up for a lack of horse­power. Left: Cruis­ing at a leisurely 65mph, the “9” could barely get the rudi­men­tary air­speed in­di­ca­tor off the peg.

Be­low: The life span of an OX-5 was of­ten as short as 50 hours. Gil­more was an early oil com­pany that spon­sored many rac­ing and airshow air­planes in the 1920s and ’30s.

Above: The WACO 9 pic­tured was one of the very first air­craft man­u­fac­tured by the leg­endary com­pany.

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