The development of aircraft dope in 1911 was a major technical development, and its use was quickly adopted by all manufacturers. This performed a number of functions, proofing the fabric against oil and petrol contamination, and also tightening the fabric. Configuration At the 1909 Grand Semaine d'Aviation the competing aircraft were of two different basic configurations: tractor configuration monoplanes such as the two types flown by Blériot and the Antoinette; and pusher configuration biplanes with a forward-mounted elevator, represented by the Voisin, licence-built copies of the Wright Brother's aircraft, Glenn Curtiss' No. 2 biplane and the Farman III. All the competing aircraft with the exception of the Voisin biplanes had roll control, using either ailerons or wing-warping The Wright design differed from the others in having no rear-mounted horizontal stabilising surface. Constructors of pusher biplanes almost universally adopted the use of a rear-mounted horizontal stabiliser and designs began to appear in which the front elevator was removed: the Wright Brothers adopted this configuration for their Model B of 1910. The tractor monoplane and the pusher biplane were the dominant configurations for the next couple of years, although designers experimented with various other configurations. One of the most successful pusher biplanes was the Farman III, developed by Henri Farman following a falling-out with Gabriel Voisin: he retained the basic layout of the Voisin, but incorporated ailerons (as added to his Voisin), modified the undercarriage by adding skids to prevent the aircraft nosing-over on landing and modified the structure, eliminating the nacelle in which the pilot sat and mounting the forward elevator on outrigger booms. This design was copied by many constructors, and was so influential that when Mervyn O'Gorman created a scheme for classifying the products of the Royal Aircraft Factory according to their configuration such aircraft were classified as "F.E" for "Farman Experimental. All tractor aircraft were designated "B.E" for "Blériot Experimental", although all the B.E. designs produced were biplanes, unlike the designs for which Blériot was known. The tractor biplane, which would become the dominant aircraft configuration until the 1930s, was a later development. The first aircraft of this type was the De Pischoff biplane which was built in 1907 but was not successful. The first aircraft of this type to fly was the Goupy No.2, flown in March 1909: the design was described by flight as "somewhat unusual", and Breguet described his Type III tractor biplane as a