If you’re reading this, chances are you’ve heard of Waco aircraft. The name derives from the last initial of its one of founders, George Weaver, and an abbreviated form of Aircraft Company, hence Waco.
Weaver and his partners set up business in Ohio in 1920 under the Waco name. The company became Advance Aircraft for awhile, but the biplanes are called Wacos, pronounced Wah-co, not Way-co.
Aviation entrepreneurs of the era were full of enthusiasm and optimism, even as they struggled against a post-World War I glut of surplus Curtiss Jenny biplane trainers and ubiquitous Curtiss OX-5 V-8 engines.
Early Waco biplanes made use of some Jenny structure, but all-new designs from the company made their mark with the Waco Model 9 (Approved Type Certificate 11) of 1925 and the evolved Model 10 (Approved Type Certificate 13) of 1927.

These two biplanes put Waco Aircraft on the map, and helped give the company the bona fides to carry on design and production of a wide array of successful biplanes for the next two decades.
The Model 9 was a trim design that used a pleasing cowling to semi-enclose the utilitarian 90-horsepower OX-5 motor. With all the attention spent on designing the cowling, the OX-5’s necessary radiator hung below the top wing, looking almost like an afterthought.
The first Waco 9s had upper wing ailerons that were flush with the wing planform. By 1926, large elephant-ear ailerons gave the Model 9 its roll authority.

To the delight of barnstormers and anyone who wanted to share the thrill of open-cockpit flight, the Waco 9 was designed with a front seat wide enough for two, with the pilot ensconced in his own cockpit just to the rear. Elwood Junkin, known as Sam, is generally credited for the design of the successful Waco 9.
The mainwheels of the Waco 9 were attached to a conservative straight axle landing gear. Waco designers found the sweet spot for innovation that did not overrun tried-and-true construction of the era.
The fuselage was welded steel tubing, taking advantage of this improvement over earlier wire-braced wood fuselage members in aircraft like the Curtiss Jenny.
The result was a biplane that gained early commercial success. A pair of Model 9s flew in the Ford Air Tour of 1925, an event intended to promote aviation in the post-World War I era. Three Model 9s participated in the 1926 iteration of the Ford event.
Engines in two of these three Model 9s were uprated six-cylinder inline Curtiss C-6 engines of 160 horsepower, while the third flew behind a Hispano-Suiza A-model engine producing 150 horsepower. While the OX-5 was the norm for Waco 9s, other powerplants included the Curtiss OXX-6, a 100-horsepower eight-cylinder engine.
The Model 9 proved capable as a floatplane with a pair of Edo pontoons, one of the first OX-5-powered aircraft to do this with success. Nonetheless, historian Joseph Juptner recounted a story of a floatplane Model 9 that could be overtaxed if two large front seat passengers climbed aboard for the same flight.
The Waco 9 had a production run of about three years before the improved Model 10 took over shop capacity. Model 9s initially sold for $2,500, gradually lowering to $2,025.

The Waco Model 10 improved on the already popular Model 9, and further burnished the company’s reputation.
Dimensionally within inches of its predecessor, the Waco 10 shunned the elephant ear ailerons on the top wing, using instead four narrow chord ailerons on the top and bottom wings.
In its introductory year of 1927, it is said the company built the equivalent of one Model 10 each day of the week — at least 365 Model 10s were tallied that year.
Most used the OX-5 motor, some the OXX-6, and a few tried air-cooled radials.
One quick recognition feature for the Model 10 is its use of a streamlined fairing behind the pilot’s head, a feature the Waco 9 lacked. The Model 10 also ventured into wide track split-leg main landing gear that used oleos for shock absorption. The tailskid was a leaf spring device. Design of the Model 10 is generally credited to Charles Meyers.

A full-page magazine advertisement in 1927 touted the virtues of the Waco 10. Including years of collaboration before they formed a company, the Waco/Advanced Aircraft advertisement said the Ten “stands for the years the WACO organization, intact, has been improving airplane performance and utility for peace-time use.”
While many texts print Waco in upper and lower case, the company’s 1927 advertisement adhered to the tenets of an acronym by capitalizing all of WACO.

A year later, the company didn’t even reference the Model 10 when selling it as simply the WACO in a 1928 advertisement: “There is nothing untried, unproved, or in any way experimental about the WACO. It embodies the engineering principles gained in the ten years of airplane construction. Take the stick of this acknowledged leader and feel for yourself the almost arrow-like takeoff and quick climbing ability. Give her the gun and feel the thrill of its speed. Set her stabilizer and fly with hands off. Bring her down and land on the cushion-like hydraulic shock absorbers without the slightest jolt or jar. When you have done this you will realize why every one that has seen the WACO is acclaiming it as the outstanding leader.”
By 1929, the Advanced Aircraft name was replaced by Waco Aircraft as the company name.
Cross-country races of the 1920s afforded general aviation aircraft a chance to show their capabilities and garner media coverage. The 1927 Air Derby launched from New York and had Spokane, Washington’s Felts Field as its destination. Charlie Meyers flew his Waco 10 to a first place finish in the derby’s Class B division. He traversed 2,352 miles in a total flying time of 30 hours and 23 minutes, with a 28-minute lead over his nearest rival.

Flying with another Approved Type Certificate (number 41), the Whirlwind Waco was essentially a Model 10 modified to incorporate a Wright J-5 radial engine instead of the faithful, but aging, OX-5. With 220 horsepower, the J-5 more than doubled the power of an OX-5, and made the Model 10 a high performance aircraft of its day.
All that power came at a price, though. The Waco Sport, as this variant was sometimes called, had an initial price tag of $7,215 in 1928.
Further testament to the Waco 10 airframe’s usefulness came with Approved Type Certificate number 42, recognizing the mating of Hispano-Suiza liquid-cooled V-8s typically of 150 and 180 horsepower. Prices ranged from a bit over $3,900 to more than $4,000 depending on the engine. Other radial engines, even a diesel, powered some of the Model 10s.

The well-received Waco 10 propelled Waco into the 1930s boom in biplane developments, coinciding with a company nomenclature change that used every letter of the alphabet to describe variations in Waco aircraft in three-letter combinations. Probably the most recognized alphabet-soup Waco is the later UPF-7 open cockpit biplane, a contemporary of the Stearman PT-13 and the Naval Aircraft Factory N3N trainers — a topic for another time.
Photos used with this article came from the collection graciously shared by historian Gerald Balzer.
SUPERB ARTICLE!!! The photo of “Miss Waterloo” looks like it was taken somewhere in the Los Angeles area (hence the oil derrick in the distance). Is that correct?