Langley Aerodrome No.5
Throughout the winter and spring months of 1894, work proceeded to complete No. 5 and retrofit No. 4 with a bigger set of wings. No. 5 was a large machine, with a wingspan of 13 feet 8 inches, length of 13 feet 2 inches and height of 4 feet 1 inch. Weighing 30 pounds, it was fitted with a new and more powerful single-cylinder steam engine. Trials resumed once again on October 7, 1894, after the summer layoff. The crew practiced using a new launching system. After a few throws with nonpowered “dummy” Aerodromes and some minor adjustments, the launcher seemed to be working perfectly. The rebuilt No. 4 was prepared for flight at once. Unlike previous attempts, the model launched perfectly, but then the wings twisted, plunging it into the water. Although it was late in the day, Aerodrorne No. 5 was readied for a trial. Again, the launching system worked perfectly, but as the Aerodrome left the rail, it nosed up steeply, slowed and then slid backward into the Potomac. To everyone’s surprise, Langley was ecstatic. He thought he saw signs of progress for the first time.
Over the next two months, Aerodromes No. 4 and 5 were launched numerous times. The launcher continued to work well, but the models just would not fly. By late November, the team had again retreated to the warmth of the Smithsonian’s shops, where serious static experiments were conducted to determine the strength of the wings. As Langley ordered, No.4 and No. 5 “were inverted, and sand was spread uniformly over the wings until its weight represented that of the machine.” Langley was shocked by the lack of stability and general weakness of the structure when loaded in that manner. More modifications were in order, including a new system of guy wiring for No.5. The changes to No.4 were so extensive that everyone felt jus-tified in renaming it No. 6.
The No.5 had a metal tube-fuselage structure that housed the engine, the boiler, and other components of the propulsion system. The wings and tail were wood-frame, covered with fine silk. The power plant was a single-cylinder, one-horsepower steam engine equipped with a double-action piston with a slide valve, and a flashtube boiler fired by a pressure burner that vaporized gasoline. The engine drove twin propellers, centrally mounted between the front and rear sets of wings, through a system of shafts and bevel gears. The aircraft weighed approximately 11kg (24.3 lb) ready for flight.
Quantico flight testing began again in early May 1895. Three attempts using No. 5 and No. 6 were considered failures. The longest time aloft was only six seconds.
After more than three years of intensive work, Langley was feeling pressure from many sources to show better results. His critics were becoming more vocal. Having exhausted all the available brainpower within the Smithsonian, Langley decided to conduct an outside search for technical help. He found Augustus Moore Herring.
Then came the watery failure of Aerodrome No. 6 on May 6, 1896. Soon afterward, having instructed his staff to ready No. 5 for a trial, Langley moved to a better vantage point on the shore of tiny Chopawamsic Island. This time, Edward Chalmers Huffaker was responsible for launching the machine. Forty-year-old Huffaker had earned a master’s degree in physics from the University of Virginia before becoming an aeronautical protégé of Octave Chanute. Impressed by Huffaker’s credentials, Langley had hired Edward to assist with the Aerodrome project. Later, because of Chanute’s influence, Huffaker was an invited guest of the Wright brothers for their 1901 gliding trials near Kitty Hawk, N.C.
Alexander Bell, the official observer, was on the port deck with a nervous Smithsonian photographer who had earlier missed taking a photograph of No. 6 splashing into the Potomac. Langley had angrily told him not to let it happen again. When the steam pressure reached a predetermined 150 pounds, the signal was given to go. At 3:05 p.m., Aerodrome No. 5 catapulted from the launch rail. Unlike earlier attempts, the throw was perfect - slightly nose high with its wings level. At first, the machine dropped three or four feet but then began to climb as it headed into a slight breeze from the north. The workmen, accustomed to hauling soaked and broken Aerodromes out of the water after a failure, were astounded to see the big dragonfly actually remain aloft.
The machine started a gentle right turn, passing almost directly over Langley’s head. It continued flying this pattern until it reached a maximum estimated altitude of 80 feet. After about one minute and 20 seconds, the propellers suddenly stopped turning, probably from lack of steam to the engine. To everyone’s surprise, the model glided beautifully for another 10 seconds before landing lightly on the surface of the bay, 425 feet from the houseboat. The Aerodrome had made three complete circles, each with an estimated diameter of 300 feet, as it drifted to the northwest. Calculations revealed that it had traveled about 3,300 feet in 90 seconds, generating a speed of between 20 and 25 mph.
The workmen retrieved the machine, then dried and carefully re-guyed the wings, one of which had sustained a kink. Langley believed that the shock of launching or the air pressures of flight might have caused the problem. He also sug-gested that the right-hand turn may have been caused by the wing’s misalignment. No.5 was ready to fly again within two hours. At exactly 5:10 p.m., the model was off on another successful flight. As before, the Aerodrome made three ascending circles to the right, reaching a maximum altitude of 60 feet. When the propellers finally stilled, the model pitched slightly nose down and glided maestically to a perfect water touchdown. Calculations showed it had flown about 2,300 feet.
On both occasions, the Aerodrome No.5 landed in the water, as planned, because, in order to save weight, it was not equipped with landing gear. 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).
The Aerodrome No.5 was transferred in 1905 from the research component of the Smithsonian to the United States National Museum, the entity of the Institution which at that time housed and cared for historical materials. The No.5 was first restored in 1975. When the aircraft was in need of restoration a second time in 1993, the wing structures were considered to be too fragile to support the new silk covering. The originals were placed in storage to preserve them and accurate reproduction wings were made for exhibition purposes. The rest of the aircraft is original.
Wingspan: 4.2 m (13 ft 9 in)
Length: 4.0 m (13 ft 2 in)
Height: 1.3 m (4 ft 3 in)
Weight: 11.4 kg (25 lb)