Published on March 11, 2013
“One of the most important items recently chronicled in Flight was that recording the achievement of Lieut. J. W. Dunne, who, at Eastchurch in the Isle of Sheppey, few a distance of 2 1/4 miles on a machine of his own design, which displayed so much natural stability as to render the use of the control levers totally unnecessary except so far as they were required for the purpose of directing the course.”
So wrote the editors of Flight in its June 18, 1910, issue, referring to John William Dunne’s D.5 flying wing — what they didn’t mention was that it was the world’s first true flying wing aeroplane. Nonetheless, the editors continued:
“There is no doubt that this flight marks an important period in the development of the aeroplane, and although the outcome of it can only be vaguely surmised, this in no way detracts from its present importance, and should increase, rather than otherwise, the amount of interest in the machine itself.”
The First True Flying Wing
The Dunne D.5 was the fifth in a series of unique designs within Great Britain that explored unconventional configurations for flight. The first four such designs were officially funded, but not the fifth. With that design, the D.5, Lieut. Dunne had truly achieved something historic making successful test flights on this date in aviation history, March 11, 1910. Despite the advantages of Dunne’s flying wing, the basic concepts would not be picked up and duplicated, nor become popular. As the D.5 took to the air day in the hands of its designer, who served also as its test pilot, nobody could yet know that. The observers that day were instead rightfully in awe of the stability and performance of the plane and the scientific process that had led Dunne to the design.
The editors of Flight reviewed the evolution of the design:
Lieutenant Dunne pursued his investigations of the problem of natural stability in the true spirit of science. He did not start with an idea and try to prove it; in fact, he has had very little time in which to evolve abstract theories that will fit in with the why and wherefore of every part of his machine. His is the sort of practice on which theory is founded. He set himself to observe. He made models and he watched them fly. He studied the works of others and he compared notes. As a result, he would tentatively adopt some general idea, such as, for instance, that in any stable flying machine, of which the main supporting surfaces are cambered aerofoils, the correct overall fore and aft length is largely dependent upon that of the span. It is for this reason, among others, that the wings of the Dunne aeroplane slope [sweep] backwards from the body to the extremities. The machine has no tail, as ordinarily understood, but it has a very considerable fore and aft length beyond that represented by the mere chord of the supporting surface.
Another general principle that he was forced to adopt, as a result of his own experiments and those of others, was that the tail plane and the main planes of a naturally stable aeroplane should make a dihedral angle with one another. Now, there is no tail plane on the Dunne machine, but the wings themselves are twisted so that the angle of incidence at the tips is less than at the centre, wherefore the principle of the dihedral angle is, as will be seen, adhered to, although the form of it is so extraordinary as to suggest, at first sight, that there is no such comparison. As for the why and wherefore of innumerable other points of interest it would be almost impossible for anyone, even the inventor himself, to say; they have just been arrived at by a long and painstaking series of trials.
Construction Quality and the Innovative Wing
The editors of Flight took great pains to point out the quality of the construction of the Dunne D.5 biplane, taking special care to congratulate and salute the company with whom Lieut. Dunne had invested the manufacturing:
The Dunne aeroplane is a biplane, and was constructed by Short Brothers at Shellbeach to the designs of Lieut. J. W. Dunne, who is responsible for all the calculations concerned therewith, while Short Bros. themselves were given a free hand in the choice of material and fittings. As far as the actual construction itself is concerned, therefore, it is not necessary to say much in detail, for the machine is a typical example of the substantial and high-class workmanship with which that firm have already made a name, and with which our readers are already familiar.
The outstanding feature of the Dunne biplane is the arrangement of the main planes, V fashion, as viewed from above. In plan the machine is like an arrow head, the main planes sloping sharply backwards from the centre where they join the body. Their extremities lie a little behind the rear end of the body, and thus the wings themselves constitute the greatest fore and aft dimension as well as the greatest span….
The D.5 had a 46 foot wingspan whose sweep defined a total length of 20 feet, 5 inches. The rudders were located quite ingenuously at the wingtips, forming a box structure that enhanced the strength of the airframe. Empty, it weighed 1,550 lbs — Flight thought a bit heavy, but certainly acceptable as an overbuilt prototype for testing purposes. Equipped with a 60 hp Green engine that drove two propellers, the aircraft proved to have a maximum speed of 45 mph. In a word, it was revolutionary.
Final Notes and Further Developments
By 1911, the next Dunne flying wing featured even more sweep back and the engine was a Green 50 hp connected directly to a single propeller. Dunne also developed monoplanes and innovated a drooping wing tip for better stability and improved flight characteristics. He pioneered a new understanding of washout and its effects on stalling. In addition, he combined the concept of ailerons with elevators into his wingtip elevons, again pioneering new engineering to meet his flying wing’s needs. As a control system, his unorthodox design was revolutionary and intuitive at the same time — it involved two levers, one to each side of the pilot for each of the two elevons. These were manipulated separately by the pilot, rather than a single interconnected aileron configuration where the surfaces work in perfect, coordinated opposition. The control system offered natural advantages that are beyond the reach of interconnected aileron and elevon systems, allowing more intuitive, rudderless control and the ability to differentially create yaw through unopposed or uncoordinated control movements.
Further development of the Dunne biplane continued unabated for some time, even if it was without British government funding. Tailless, it was the world’s first practical and stable flying wing. Why the developments and innovations that Lieut. Dunne pioneered were not continued is beyond understanding. Had they been, the history of aviation design would have been markedly different. Indeed, it wasn’t until World War II (and again after a long break in more recent years) that a fuller appreciation of the advantages of flying wings has emerged. We can thank Lieut. Dunne for his scientific work, even if from across more than a century of time. He was a true pioneer, far ahead of his time.
One More Bit of Aviation History
The Burgess-Dunne D.8 of 1914 carried forward the design of the D.5 into a successfully marketed hydro-aeroplane (seaplane). The D.8 was licensed for manufacture to Canada where it served the Canadian government for many years. At FiddlersGreen, they offer a wonderful card stock model of the Burgess-Dunne D.8. Click here to visit their page and download your own model — add an engine and it flies too! In fact, I suspect that the design would make the perfect ultralight radio-controlled, electric model airplane!
Today’s Aviation Trivia Question
Which entity within the British government secretly funded Lieutenant J. W. Dunne’s D.1 through D.4?
2 thoughts on “The Dunne Flying Wing”
The War Office, I think.
The Dunne Collection in the Science Museum archive reveals two linked reasons why the Dunne type failed to catch on. First, even back then the development of a new conception had gone beyond the means of a single experimenter. Dunne had not enough resources to carry out the necessary development programme. Second, then WWI got in the way. The great armaments firm, Armstrong Whitworth, took over Dunne’s syndicate and began building a new D.11 prototype but, with the outbreak of war, all resources were diverted to immediate war work and the Dunne project abandoned.
May I also note a couple of corrections. The end curtains of the biplanes were originally added to improve tip efficiency by limiting sideways flow, the same function provided by modern winglets. The stabilising action was helpful but not strictly needed. Contrary to one caption they had no movable rudders.
The control system did not allow for independent yaw control. The elevons acted to induce carefully balanced roll and yaw together, making turning very easy for the novice pilot. However, crosswind landings were extremely dangerous and several accidents happened that way. You had to fly well downwind of the landing area and then turn into the wind to land. Postwar attempts to resurrect the Dunne formula, whether in the UK (Westland-Hill, Granger), US (Smith, Waterman) or Germany (Lippisch), all added a conventional rudder, pedals and joystick.