Langley Quarter-scale Aerodrome

Samuel Langley's aeronautical experiments appeared to have concluded with the successful flights of his Aerodromes Number 5 and Number 6 in 1896, but privately he intended to build a full-sized, human-carrying airplane. Langley's simple approach was merely to scale up the unpiloted Aerodromes of 1896 to human-carrying proportions. The construction details and distribution of stresses on the Aerodrome A, as the full-sized version was called, were based on the successful performance of a gasoline-powered model, one-fourth the size. This exact scale miniature, known as the Quarter-scale Aerodrome, made two flights of 46 m (150 ft) and 108 m (350 ft) on June 18, 1901, powered by a five-cylinder radial internal combustion gasoline engine of about 3.2 horsepower. Between 1901 and 1903, the engine was rebuilt to produce slightly more than three horsepower, after which a final flight of 308 m (1,000 ft) was made on August 8, 1903. Because the structural and control requirements for a full-sized, piloted airplane were very different, the satisfactory flights of the Quarter-scale Aerodrome masked its flaws as a design prototype for the Aerodrome A. When twice attempted to fly in 1903, the Aerodrome A met with disastrous results, ending Langley's aeronautical experiments entirely.

Professor Samuel Pierpont Langley (1834-1906) was a leading scientific figure in the United States in the latter nineteenth century, well known especially for his astronomical research. He became the third Secretary of the Smithsonian Institution in 1887. Langley had begun serious investigation into heavier-than-air flight several years earlier while at the then Western University of Pennsylvania in Pittsburgh (now the University of Pittsburgh). He had erected a huge, 18.3 m (60 ft) diameter whirling arm at the university's Allegheny Observatory to perform aerodynamic research. At full speed, the tips of the whirling arm approached seventy miles per hour. Langley mostly ran tests with flat plates, but he also mounted small model airplanes he called aerostats, and even stuffed birds, on the arm. He also conducted an extensive series of experiments with rubber band-powered models.

Langley described these investigations and provided a summary of his results in Experiments in Aerodynamics, published in 1891. He then moved away from purely theoretical aerodynamic research, and began work aimed at engineering an actual flying machine. In 1891, he started to experiment with large, tandem-winged models, approximately 4 m (13 ft) in wingspan, powered by small steam and gasoline engines. Another large whirling arm, 9 m (29.5 ft) in diameter, was set up at the Smithsonian to test curved wing shapes and propellers, probably in connection with the design of these large powered models that Langley called aerodromes.

After several failures with designs that were too fragile and under-powered to sustain themselves, Langley had his first genuine success. On May 6, 1896, Langley's Aerodrome No. 5 made the first successful flight of an unpiloted, engine-driven, heavier-than-air craft of substantial size. It was launched from a spring-actuated catapult mounted on top of a houseboat on the Potomac River near Quantico, Virginia. Two flights were made that afternoon, one of 1,005 m (3,300 ft) and a second of 700 m (2,300 ft), at a speed of approximately 25 miles per hour. On November 28, another successful flight was made with a similar model, the Aerodrome No.6. It flew a distance of approximately 1,460 m (4,790 ft).

Langley's aeronautical experiments appeared to have concluded with the successful flights of Aerodromes No. 5 and 6, but privately he intended to raise funds to begin work on a full-scale, human-carrying aircraft. He believed his only real hope of securing the kind of funding necessary was from the federal government. The breakthrough came when Langley's friend and colleague, Charles D. Walcott, of the U.S. Geological Survey, offered to present the proposal to President McKinley. A panel was created to review Langley's work up to that time. The panel, which included Assistant Secretary of the Navy, Theodore Roosevelt, met at the Smithsonian in April 1898. After a week of deliberations, they approved a grant of $50,000 from the Board of Ordnance and Fortification for Langley to construct a full-sized aircraft. The outbreak of the Spanish-American War only five days earlier contributed to the panel's favorable and speedy decision.

Serious work on the airplane, referred to as the Great Aerodrome, or Aerodrome A, began in October 1898. Langley's simple approach was merely to scale up the unpiloted Aerodromes of 1896 to human-carrying proportions. This would prove to be a grave error, as the aerodynamics, structural design, and control system of the smaller aircraft were not adaptable to a full-sized version.

The construction details and distribution of stresses on the Aerodrome A were based on the successful performance of a gasoline-powered model, one-fourth the size. This exact scale miniature, known as the Quarter-scale Aerodrome, made two flights of 46 m (150 ft) and 108 m (350 ft) on June 18, 1901, powered by a five-cylinder radial internal combustion gasoline engine of about 1.5 horsepower designed and built by a New York inventor named Stephen M. Balzer. A native of Hungary, Balzer had constructed the first automobile in New York City in 1894. Between 1901 and 1903, the engine was rebuilt to produce slightly more than three horsepower, after which a final flight of 308 m (1,000 ft) was made on August 8, 1903. Because the structural and control requirements for a full-sized, piloted airplane were very different, the satisfactory flights of the Quarter-scale Aerodrome masked its flaws as a design prototype for the Aerodrome A. When in 1903 Langley twice attempted to fly the scaled-up, full-sized, piloted version of the Quarter-scale Aerodrome, i.e., the Aerodrome A, he met with disastrous results, thus ending his aeronautical experiments entirely.

The entire structure of the Quarter-scale Aerodrome is original, but the fabric covering has been replaced.