The Aircraft of J W Dunne

J W Dunne's experiences as a soldier in the Boer War, especially what he saw of reconnaissance balloons, convinced him that any successful warplane must be inherently stable and easy to fly, allowing the airman to concentrate on the task in hand. In particular, it should always recover from a stall and never fall out of the sky under any circumstances.

Many of the early aviation pioneers were very secretive about their aeroplanes. Then, suddenly, a new machine would fly and they could not get enough publicity to try and sell it. J W Dunne was no exception. His military background even created a desire for his revolutionary ideas to be British military secrets. But when the military lost interest and a civilian machine eventually flew, he became as hungry for publicity as anyone else. Bouts of military secrecy and public attention-seeking would alternate throughout his life, with much of his work never reaching the public gaze.

The vacuum of information, fed with little more than failing memories over half a century, has led to much imaginative gap-filling with successive historians leading each other further and further from reality. These include separate confusions between various monoplanes on the one hand and various biplanes on the other, a phantom Blair Atholl monoplane and identification of the D.9 with another aeroplane a hundred miles away in Birmingham.

But Dunne kept original records of almost all of his work, including a great many flying models, though sometimes skimping on the material saved. The account given here is drawn entirely from contemporary documents, primarily those in the Dunne archive. I have now investigated enough of them that I regard this list as pretty definitive.

Rotor aeroplanes

Following a first failed effort at a vortex-augmented "cross between a windmill and a parachute", between 1901 and 1904 Dunne experimented with horizontal-axis Magnus rotors, eventually settling on the use of auxiliary rotor wings to stabilise and augment the lift of a larger fixed wing. He sent a paper on them to the incumbent Lord Rayleigh, a notable aeronautical figure of the day, but no known copy survives. He also lodged a preliminary patent which gives a detailed text description, and sketched his design in a letter to Baden Baden-Powell.

Triplanes

On being advised that the rotor system would be too complex to be practical, he soon came up with a staggered triplane arrangement in which the gap between two tandem wings, fore and aft, was bridged by a central wing mounted above them. Besides the odd model, three versions of this design are known.

Maxim tethered glider
This was built in 1904 to Dunne's design and installed on Hiram Maxim's spinning fairground ride at the Crystal Palace. Hung from a long pole, it swung out and flew at over 100 mph (160 kph) as the ride turned. But it was not wholly stable until Samuel F Cody installed a boxkite-like tail on it.

D.2
Dunne later resurrected the idea when in 1907 the War Office forbade him from giving his latest secret design to A K Huntington. He designed a sub-scale manned glider to test the design, the D.2, but it was never built.

Dunne-Huntington
At the same time as the D.2, he produced the design for the intended machine for Huntington, who slowly built it between 1908 and 1910. He then flew it in a series of increasingly successful trials until 1913, progressively modifying it to improve its controllability and performance.

Biconical delta wing

Following the demonstrable unreliability of his Maxim design, Dunne sought a more efficient and foolproof solution. Towards the end of that same year he came up with the essence of his revolutionary concept, the tailless biconical wing.

His first design was a delta wing, taking the classic form seen in the later flexible "Rogallo" wing. He writes that he made models up to five feet (1.5 m) in span. He sent a small paper model to Lord Rayleigh, accompanied by a technical description. Although these have been lost, other models survive and Rayleigh's reply is also preserved, in which he acknowledged how prettily it flew.

Some years later, Dunne had cause to remind Rayleigh of the essentials and to include a small sketch, confirming the wing design for posterity.

Discarded studies

Finding the delta to be somewhat inefficient, Dunne pursued the idea further. He studied the flight of birds and fashioned his next models after the seagull. Diversions into the bat wing and canard foreplane followed, but then he returned to the seagull to try and simplify the shape for practical construction.

Tailless swept monoplanes (1905-1923)

The result was the Dunne monoplane design, a tailless swept wing with conical development over much of its upper surface, combined with turned-down or anhedral wing tips for improved stability and control. This was to appear in several incarnations.

1905/6 models
One of these was shown to John Capper, head of the Army Balloon Factory at Farnborough, and on the strength of it he took Dunne on as Britain's first military aircraft designer. On his arrival, Dunne initially continued work on his monoplane, but the War Office demanded biplanes and so the monoplane had to wait.

D.6
When in 1909 the military stopped aircraft work and Dunne's designs were declassified, work on the monoplane could at last be resumed. While Dunne pursued the biplane, Capper built for himself the monoplane design that Dunne drew up for him, the D.6. But the A-frame main structure proved hopelessly overweight and, despite some modifications by Dunne, it refused to fly. The D.6 has been referred to by some puzzled historians as the Dunne-Capper monoplane.

D.7
Dunne's Blair Atholl Aeroplane Syndicate rebuilt the D.6 as the D.7, and it was exhibited in a partly rebuilt state with a more conventional frame and bracing at Olympia. When finished it flew successfully but, in an extensive period of test flying, several examples were written off and new ones built, progressing from the original Green engine to a much more powerful Gnome.

D.7bis
From the outset a two-seater machine with a more powerful engine, the D.7bis was built in France by a partnership between the Syndicate and the Astra company. Once its Renault engine had been replaced by a Gnome, it flew well. But Dunne was unhappy about the weakness of its construction and had it broken up.

1923 monoplane
When G T R Hill contacted him about reviving and updating his unstallable safety aeroplane, Dunne drew up a new monoplane and sent it, with a model, to Hill. Those items are not known to have survived, but Dunne kept a drawing dated 1923. It shows his old monoplane with downturned and washed-out wing tips but with a very modern-looking tapered main plane of moderate aspect ratio. Hill went on to develop the Pterodactyl series of successful tailless prototypes.

Tailless swept biplanes

Following the War Office instruction to work on biplanes, Dunne adapted his monoplane design accordingly. Still retaining the tailless swept wing with its conical development and consequent washout at the tips, he doubled it up and discarded the droop at the tips.

Biplane models
Dunne resumed his model research, flying many small paper models in his usual way, before turning to larger ones:

D.1
At last a real, manned aeroplane could be designed. The D.1 was built in two parts, a glider with landing skids and a wheeled power module onto which the glider could be fixed, and test-flown in 1907:

D.3
1908 brought two new craft. The first was a glider, which flew well on many occasions. It was an outstanding machine for its day, although Army secrecy long hid its capabilities from the history books.

D.4
A more integrated version of the D.1B, built in a single unit and with a marginally more powerful engine, the D.4 behaved well but turned out still grossly underpowered and the progenitor of that favoured quote, "more of a hopper than a flier",

D.5
Built overweight by Short Bros. and subsequently lightened by Dunne, The D.5 incorporated a more powerful 35 hp Green engine and became the first stable aeroplane to fly.

D.8
Abandoning the twin propellers at last for a single unit mounted directly onto the engine, Dunne designated this new variant the D.8. It was to prove his most successful design:

Burgess-Dunne
When the American W Starling Burgess licensed the D.8, Dunne drew up a floatplane version for him, which he called the Burgess-Dunne. Burgess went on to build it and to derive some eighteen more machines from it. One of the early examples, possibly the original prototype itself, eventually found its way via Canada and back to England where it was, as was by now becoming traditional, forgotten.

Nieuport-Dunne
Having taken delivery of the "Nieuport-Dunne" flown over by Félix, Nieuport built their own prototype, also known as the Nieuport-Dunne. Exhibited at the Paris Salon, it differed from the D.8 in having modified aerofoils, much simplified undercarriage and overall a lightened structure. It seems not to have flown well, if at all, and soon disappeared from sight.

D.9
The first aircraft that Dick (later Sir Richard) Fairey really got his teeth into, the D.9 was an unequal-span biplane (sesquiplane) begun in 1913. For whatever reason the design turned sour and the drawings were never finished.

D.10
Dunne wanted to try out a revised wing design. calling it the D.10, he built a set of wings and grafted them onto a D.8 fuselage. I have found no record of flight testing, though trim tests were carried out. Dunne later said that it was another failure.

Armstrong Whitworth D.11
Shortly before the outbreak of war, Dunne's Syndicate sold its assets to Armstrong Whitworth. Dunne updated the D.8 to produce a new D.11 design. Work on a prototype at Armstrong's was just gearing up when war broke out and the design was never progressed.

Tailless swept monoplanes (1939-44)

D.12
In 1939 Dunne dusted off his old ideas to update them for modern warfare. Various ideas appeared, including single-engined fighters and twin-engined reconnaissance/bombers, all under the banner of the D.12. The inevitable models explored variations on a swept and gently tapered wing, of relatively conventional appearance but generally cleaner and more slender than the pterodactyls. Among them they threw up an especially promising design:

Updated 12 Dec 2018