The Wright Brothers

It is now a well-known fact the Wright brothers are credited with being the first to achieve sustained, powered flight in an airplane using their Wright Flyer I, on 17 December 1903. The flight took place at Kittyhawk, North Carolina, USA, with Orville Wright (1871-1948) at the controls. Several other pilots from different parts of the world also claim to be the first to fly, before the Wright brother’s famous first flight. However, the Wright’s first flight has long been recognized as the first successful ‘controlled and sustained flight’ in heavier than air aircraft, which the other pilots failed to achieve The Wright’s success was achieved through having a suitable engine and propeller combination. Both were of course, designed and made by them with the assistance of their mechanic Charles Edward Taylor (1868-1956. Their propeller design calculations were remarkably accurate, with the prop twist being correct for the speed ratio of their props. When they designed their props, they had to rely on their own calculations because not many (if any at all) calculations were available on aircraft propellers back in those days of early flight. As we shall see shortly, various theories were available for ship’s propellers which have since been applied to aircraft propellers. Each prop at 350 RPM produced sixty – seven pounds of thrust. The propellers were hand carved from three laminations of spruce wood and painted with aluminium to prevent their work from being copied by any competitors. It is not known which of the two Wright brothers carved the props; the design was never patented. Because the props were contra-rotating, it was not a simple matter of making the second prop a copy of the first one; it had to be a mirror image due to rotating in the opposite direction. Their mechanic Charles Taylor built the 12 horsepower (9 kW) four – cylinder engine, which turned by train drive the two 8.5 feet (2.59 m) propellers. One chain was twisted into a figure of eight loop to drive the second prop in the opposite direction to the first. Tests conducted at the NASA Langley Full Scale Wind Tunnel, revealed an efficiency of 81.5% on the Wrights’ 1911 propellers, a remarkable achievement for that era. Their efforts were a great contribution to the development of aircraft and propellers that have since followed.

Normal stress forces acting on the propeller are to be expected and are allowed for in the modern propeller’s design but undue stress can lead to disaster. In fact, the first person to be killed in an aircraft accident was due to propeller failure. Lt Thomas Selfridge was killed while flying with Orville Wright in 17 September 1908. Orville was severely injured but survived.