The Aircraft of J W Dunne

Early: Rotor aeroplanesMaxim tethered gliderDunne-HuntingtonBiconical deltaDiscardedMonoplane modelsBiplane models
Main: D.1D.2D.3D.4D.5D.6 "Dunne-Capper"D.7D.7bisD.8 (Carden and Felix)D.8bisD.9D.10D.11 (Armstrong Whitworth)D.12
Derivatives: Burgess-DunneNieuport-Dunne (Nieuport)1923 monoplane (Hill Pterodactyl)

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 secretive about their aeroplanes. Then, suddenly, a new machine would fly and they could not get enough publicity for 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 militaristic 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. Some muddles of subsequent historians, notably the phantom monoplane of Blair Atholl and the "James" monoplane, are conspicuous by their absence.

Blue highlight shows manned craft which actually flew.

Brown highlight shows manned craft which were built but failed.

Rotor aeroplanes

Following a first failed effort at a vortex-augmented "marriage of the kite and the windmill" in 1901 or 1902, 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, President of the Aeronautical Society of Great Britain.

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. It was essentially Langley's "Aerodrome" with a third wing inserted above and between the others. Besides the odd model, three versions of this design are known.

Maxim tethered glider
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 sufficiently stable until Samuel F Cody installed a boxkite-like tail on it. Dunne and a few other hardy souls later took rides on it, "clinging to it like a monkey".

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 of the main powered machine for Huntington, who slowly built it between 1908 and 1910, eventually turning to Short Bros. to take on the job. He then flew it in a series of increasingly successful trials until 1914, progressively modifying it to improve its controllability and performance.

Biconical delta

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 "Rogallo" hang gliders although Dunne's wing was probably rigid rather than flexible. 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 acknowledges how prettily it flew.

Some years later, Dunne would include it in his main patent and presently had cause to remind Rayleigh of the essentials, including a small sketch of the 1905 model and confirming its provenance for posterity.

Discarded studies

Before discovering his delta, he had studied the "zanonia" or "crow" wing popularised by several of his colleages. He rejected it firmly because it was not directionally stable but needed a tail, which by its nature introduced dangerous discontinuities in aerodynamic characteristics during the stall. It also added to the complexity of any control arrangement.

Finding the delta to be somewhat inefficient, Dunne pursued the biconical idea further. He studied the flight of different birds more closely 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 its conical development subtly repositioned to create turned-down or anhedral wing tips for improved stability and control. This was to appear in several incarnations.

1905/6 models
A model monoplane was shown to Col. John Capper, head of the Army Balloon Factory at Farnborough, and on the strength of it he took on Dunne as Britain's first official 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 "Dunne-Capper monoplane"
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 publicly pursued the D.5 biplane, Capper secretly built for himself the monoplane wing that Dunne drew up for him next, the D.6. But the A-frame main structure which someone added to it proved hopelessly overweight and, despite some modifications by Dunne, it refused to fly. The sudden public appearance of the finished D.6 for its flight trials has caused some puzzled historians to refer to it as the Dunne-Capper monoplane.

D.7
Dunne's Blair Atholl Aeroplane Syndicate rebuilt Capper's 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 original 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 Dunne about reviving and updating his unstallable safety aeroplane, he 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, the first of which bore a strong resemblance to some aspects of the drawing.

Tailless swept biplanes

Following the War Office instruction to work on biplanes, Dunne adapted his monoplane design accordingly. Still retaining the tailless swept wing planform, he realigned the cone yet again to avoid any droop at the tips and merged a second, smaller cone into the wing surface.

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

D.1
A real, manned aeroplane could now 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 flyer for its day, although Army secrecy long hid its capabilities from the history books.

D.4
A more integrated rebuild of the D.1B as a single unit and with a marginally more powerful engine and other modifications, the D.4 behaved well but turned out still grossly underpowered and the progenitor of that popular quote, "more of a hopper than a flier".

D.5
Built overweight by Short Bros. and subsequently lightened by Dunne, The D.5 was his civilian syndicate's first machine. It incorporated a more powerful 35 hp Green engine and in 1910 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 his next biplane 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 built it and went on to derive some eighteen more machines from it. On the outbreak of war one of the early examples, possibly the original prototype itself, found its way back via Canada to England where it was, as was by now becoming traditional, forgotten by the War Office.

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 also disappeared from sight when war broke out.

D.9
The D.9 was an unequal-span biplane (sesquiplane) begun in 1913, apparently as a successor to the rather slow and antiquated D.8. For whatever reason the design turned sour and the drawings were never finished.

D.10
Dunne went back to the drawing-board and developed another revised wing design, calling it the D.10. Rather than build a whole new prototype he built a set of wings and grafted them onto a D.8 fuselage. Trim tests were carried out and his test pilot N S Percival probably took it out for flight testing. 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 yet again to produce a new D.11 design. Work on a prototype at Armstrong's was under way when war broke out and the project was shelved.

Tailless swept monoplanes (1939-44)

D.12
In 1939 Dunne dusted off his old ideas to update them for modern warfare. Various applications were considered, including single-engined fighters and twin-engined reconnaissance/bombers, all under the banner of the D.12. The inevitable models explored variations on a graceful long, swept and gently tapered wing attached to a streamlined fuselage, being overall more clean and slender than the Pterodactyls. Among them they threw up an especially promising design with quite radical aerodynamics:

Updated 19 August 2019