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SOME AIRCRAFT INNOVATIONS, such as ailerons and joystick, proved lasting. Others may have been based on sound engineering principles, but this wasn’t enough.
An example is the patented Gallaudet Drive, as devised by Edson Fessenden Gallaudet, late of the Yale faculty (which is also part of the tale).
At quick glance, the Gallaudet floatplane looks orthodox enough for 1916: open cockpits for its pilot and observer, a multitude of rigging for its biplane wings—but where’s the propulsion?
Indeed, the Gallaudet Drive employed a pair of engines, together with its propeller, mounted amidships.
This unorthodoxy gave an advantage over a conventional propeller, be the latter a tractor type at the front of the aircraft or pusher at the rear: The portion of any prop closer to its hub generates thrust less efficiently than do its extremities; its hub produces no thrust whatsoever. Gallaudet claimed his Drive was almost 10-percent more efficient than a conventional design.
What’s more, a mid-fuselage prop locates an aircraft’s center of thrust coincident with its center of gravity; this, enhancing propulsion dynamics. Another benefit was its unobstructed view for observer and pilot.
Gallaudet had been experimenting with aeronautics since 1896. Several years before the Wrights perfected wing warping, he designed, built and flew a glider model featuring this control concept.
The surname may be familiar: Gallaudet’s father and grandfather were pivotal in education for the deaf. From 1897 to 1900, Edson taught physics at Yale. Having had Yale colleagues complain that his aeronautical efforts lowered the tone of their lofty institution, he gave up such activities until 1909. It was then that his Gallaudet Engineering Company built its first airplane. He received Aero Club of America License No. 32 in 1911.
In 1915, the U.S. Navy had a design competition for a light floatplane capable of shipboard use. It would be launched by catapult and hoisted back aboard after setting down on the sea. The D-1, with its Gallaudet Drive, was the most expensive of 14 entries, losing with a bid of $18,000 (more than $428,000 in today’s money). However, the Navy thought the design had sufficient technical merit to contract for a single aircraft, often identified as U.S. Navy 59A. A price of $15,000 was agreed upon, payable on official acceptance.
With its Gallaudet Drive, forward and aft portions of the D-1 fuselage were connected by a central boom of steel around which rotated its prop blades affixed to a ring gear.
Twin Duesenberg four-cylinder aero engines, each producing 150 hp, had clutch drive of the ring gear, thus giving single- or two-engine propulsion. The engines, likely derived from Duesenberg car racing, featured four valves per cylinder.
Development of the D-1—and payment of its $15,000—was hampered initially by a delay in receiving the engines and then by problems with their operation. In June 1916, taxi tests were performed on the Thames River near Gallaudet’s Norwich, Connecticut, headquarters. Based on these tests, large vertical radiators were added to augment the cooling provided by the pair embedded amidships in the fuselage.
Unorthodox aileron controls proved acceptable: As shown on the GMax model, the ailerons on each side are actuated only in the upward direction, rather than functioning both upward and downward. Later evolutions of the D resorted to dual-action ailerons with lower control horns.
Further testing was delayed by the death of the Gallaudet test pilot flying a Curtiss a few weeks earlier. The only other pilot available was unfamiliar with seaplanes and unable to get the D-1 off the water.
The D-1’s first flight was made on July 17, 1916. That day, a small hole punched in the bottom of the pontoon caused its internal pressure to rise and blow off part of its upper decking.
Other delays were caused by this pontoon repair, finding another capable pilot, and repairing damage incurred when the pontoon’s front struts failed, crushing part of the aircraft’s nose onto the pontoon.
Once this was repaired, Gallaudet’s first choice of pilot couldn’t break free from his regular job….
In the fall of 1916, Gallaudet hired Filip A. Bjorklund, a pilot with extensive experience in Sweden, England and the U.S. Among other roles, Bjorklund had instructed at the Gallaudet Flying School as well as one operated by the New York National Guard.
Bjorklund made many flights of the D-1 in October – November 1916. Drama occurred on November 23 when his rudder bar broke. Fortunately, Bjorklund’s foot nudged his passenger, who recognized the problem and centered the rudder with the forward rudder bar. Subsequent testing was precluded by worsening rain, fog and high winds along Connecticut’s Thames River.
For further testing, the D-1 was shipped to the Naval Aeronautic Station in Pensacola, Florida. It had yet to gain its Navy acceptance, and thus all costs were still Gallaudet’s.
Acceptance trials were held on January 24, 1917. Bjorklund being unavailable, the pilot was a fellow unfamiliar with the D-1. However, the craft’s recorded average top speed of 90.97 mph surpassed the contract requirement of 88 mph. Other tests, including capability of riding adrift in open sea in a 30-mph wind, were not attempted.
The Gallaudet Drive performed without a flaw. Also the steel boom connecting fore and aft fuselage sections proved sturdy. In his modern research for the Connecticut Aeronautical Historical Association published online at earlyaviators.com, Robert A. Gordon notes, “The Board of Inspection recommended that no duplicate D-1s be ordered, although they did not preclude further consideration of other designs of the Gallaudet Drive type…. It is recommended that the seaplane be accepted and paid for at once.”
© Dennis Simanaitis, SimanaitisSays.com, 2016