Lateral Control: The Saga of the Curtiss Goupil Duck

DALLAS — The Curtiss Goupil Duck story is an intriguing account of four aviation pioneers competing during the early stages of the industry. Contrary to popular belief, the Duck’s ability to fly heavier than air was not merely experimental or for commercial purposes.

The achievement of power-controlled flight on December 17, 1903, is often attributed to the Wright brothers. Additionally, in 1906, they were awarded a patent for their method of lateral control, which involved wing warping. However, it is worth noting that they acknowledged the feasibility of alternative methods at that time.

Goupil Duck with wheel undercarriage. Photo: Public Domain

Lateral Control

Lateral control, which governs the side-to-side roll of an airplane, is an essential element in maintaining flight. The ability of an aircraft to execute controlled turns serves as a visible and unmistakable indication of the successful implementation of any form of lateral control.

Even before the Wright brothers’ iconic inaugural flight, early aviation pioneers delved into the exploration and experimentation of lateral control techniques.

Through their patent application in 1906, the Wright brothers aimed to establish a monopoly on manned flight, requiring anyone constructing aircraft to pay a royalty for utilizing their patented system.

Wilbur Wright held a firm standpoint on this matter, expressing in a letter to Octave Chanute, a friend and collaborator of the Wrights, on January 20, 1910, that “it is our belief that both morally and legally, the world owes its nearly universal adoption of our lateral control system entirely to us.”

One approach to achieving lateral control is wing warping, which involves modifying the shape of the wings to create desired aerodynamic effects. While it had its advantages and disadvantages, wing warping played a significant role in early aircraft for a relatively brief period, remaining a viable option until approximately 1915.


Wing Warping vs Ailerons

Anton Herman Gerard “Anthony” Fokker, a renowned Dutch aircraft designer, emerged as a prominent advocate of wing warping, a technique he continued to champion even during World War I, despite its outdated nature.

In 1908, Glenn Curtiss, an aviation pioneer, sought to bypass the Wright brothers’ patent by implementing ailerons.

While Curtiss was not the first to employ ailerons in manned flight, that distinction belongs to Robert Esnault-Pelterie and his glider in 1904. Interestingly, British scientist Matthew Pierce Watt Bolton patented ailerons in 1868.

Ailerons, which utilize movable flaps in the wings to achieve similar outcomes as wing warping, present a significantly more efficient and straightforward solution for lateral control. Some speculate that if Bolton’s patent had been more widely known, the Wright brothers’ 1906 patent might never have been granted.

Nevertheless, the Wright brothers filed a lawsuit against Curtiss for patent infringement, marking the beginning of the historic Wright brothers’ patent wars, which endured for several years.

However, that’s a tail for another occasion.

Souvenir postcard of the Grande Semaine d’Aviation, 1909. Photo: By Unknown Author, French postcard 1909, Public Domain

Glenn Curtiss

Glenn Hammond Curtiss, a contemporary of the Wright brothers and a key figure in the early days of the United States aircraft manufacturing industry, made significant contributions as an aviation pioneer. His journey began as a bicycle courier and racer, eventually leading to his owning a bicycle shop.

As the popularity of motorbikes and their accompanying internal combustion engines grew, Curtiss developed a keen interest in them. In 1902, he started manufacturing motorcycles equipped with his own single-cylinder engines. Notably, he achieved a motorcycle land speed record of 64 mph in 1903, followed by an unofficial record of 136.36 mph in 1907. It’s important to note that during this time, Curtiss was already involved in aviation.

In 1904, Curtiss became an engine supplier to Tom Baldwin, an innovator in ballooning who successfully created the first powered dirigible in the United States. Subsequently, in 1907, Curtiss joined the Aerial Experiment Association, a group dedicated to designing aircraft. Utilizing his engines, he made significant contributions to the project as one of the designers and test pilots involved.

Glenn H. Curtiss’s pilot license. Photo: Евгения Тихонова – National Air and Space Museum, Public Domain,

The Curtiss-Wright Competition

On June 8, 1911, the Aero Club of America awarded Glenn Curtiss with the US pilot license number one, surpassing Wilbur Wright, who received license number five. Furthermore, Curtiss outperformed the Wright brothers in public aircraft demonstrations, achieving this feat on July 4, 1908. His flight of 5,080 feet earned him the Scientific American trophy and a prize of US$2,500.

This notable accomplishment marked the first public flight of a heavier-than-air aircraft in the United States, propelling both Curtiss and aviation itself into the forefront of public awareness.

Some argue that Curtiss had a more significant impact on popularizing aviation in the United States than the Wright brothers, although it is important to recognize that innovation and entrepreneurship should not be reduced to a race to be the first in every aspect. It is understandable why Curtiss sought to challenge the Wright brothers’ patent.

During the ongoing patent dispute between Curtiss and the Wright brothers in 1916, Curtiss sought to demonstrate that the Wright brothers were not the inventors of lateral control, which would potentially invalidate their 1906 patent. To achieve this, he needed to find an aircraft that predates the first powered flight in 1903, one that could not only fly but also showcase controlled turning through lateral control.

Even with the advantages of hindsight, the internet, and relatively easy access to patent information, this proved to be a daunting task. The search led Curtiss to the work of French engineer Alexandre Goupil.

A flying aircraft designed by Alexandre Goupil. The craft is a sesquiplane, which means it has two wings, one of which is significantly smaller than the other. Inside the bulbous body, Goupil imagined a steam engine driving a single propeller at the front. Image: Public Domain

Alexandre Goupil’s Monoplane

In 1883, Goupil designed a monoplane glider that resembled a bird and demonstrated apparent stability while restrained. His enthusiasm was primarily centered around his new steam engine, which weighed approximately 1,000 pounds and generated 15 horsepower. However, utilizing the engine to fly the monoplane proved to be an impractical endeavor.

Nevertheless, Goupil did achieve successful unpowered test flights. In one instance, with a 14 mph wind, the flight generated enough lift to elevate the machine and two pilots into the sky. This remarkable accomplishment, achieved without a power source, validated Goupil’s initial beliefs. Regrettably, he did not continue conducting further flight tests for reasons that remain unclear.

The final design for Goupil’s sesquiplane. The general concept remained the same, but the design was simplified, as was the wing geometry. Image: Public Domain

The aircraft featured a sleek fuselage shaped like a bird, equipped with a forward-facing propeller, a horizontal tail, and a rudder aft. The flying machine relied on skids for support. The pilots had the ability to move along a hinged seat, operating two compact horizontal surfaces located at the front. These surfaces could function together as elevators or independently as ailerons, but their primary purpose was to maintain natural balance rather than to initiate banking or turning maneuvers.

Goupil dubbed his machine an airplane, one of the first to use the term.

Glenn Curtiss, or one of his colleagues, astutely recognized the aircraft’s potential and the feasibility of installing an engine. If a steam engine could be accommodated, it was certainly plausible to incorporate a modern aircraft engine that would be lighter and deliver superior power.

The Curtiss-Goupil Duck takes to the skies. Photo: Public Domain

The Curtiss-Goupil Duck Takes to the Skies

Rephrased: Curtiss constructed a dock at his Buffalo, New York plant based on Goupil’s original patent drawings and a description found in Le Local Museum Ariens. He initially tested the aircraft on wheels instead of skids, then on floats, and eventually returned to using wheels. To power the aircraft, Curtiss opted for the Curtiss OXX-6 engine, which was selected due to its weight reduction of 600 pounds compared to the steam engine proposed by Goofy, while providing a significantly more powerful output of 100 horsepower.

On January 19, 1917, the contraption took its inaugural flight, first maintaining a straight and level path and then successfully completing a circular flight. Although Curtiss implemented several important enhancements to the original design, including control linkages, engines, and longer wings, the fundamental core design remained unchanged. This demonstrated that lateral control had existed prior to the Wright brothers’ patent, substantiating Curtiss’ claim.

Nevertheless, Curtiss was unable to utilize this evidence to challenge the Wright brothers’ status as the inventors of lateral control. The Curtiss-Wright patent dispute was resolved through arbitration in 1917, coinciding with the escalating involvement of the United States in World War I. The US government successfully persuaded Orville Wright to release the patent, citing the urgent need for combat aircraft.

Featured image: “Curtiss Goupil Duck – 1917.” [Plate also dated May 5, 1916] Public Domain. Article source: Jerry Cantlow via YouTube.


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