Dunne-Huntington triplane

Dunne-Huntington triplane
With original Wolesley engine and twin propellers.
Role	Experimental prototype
Manufacturer	A. K. Huntington
Designer	J. W. Dunne
First flight	1910
Retired	1914
Primary user	A. K. Huntington
Number built	1

The Dunne-Huntington triplane, sometimes referred to as a biplane, was a pioneer aircraft designed by J.W. Dunne and built by A. K. Huntington. It was of unusual staggered triple-tandem configuration and an early example of an inherently stable aeroplane.

History

While working for the Army at Farnborough in 1907, J. W. Dunne agreed to design a stable aeroplane for the civilian enthusiast and metallurgy professor A. K. Huntington. Forbidden to use his secret Army design, he based it on a previous idea for a heavily-staggered tandem triplane that had been trialled by Hiram Maxim for a fairground attraction. In the winter of 1907-08 he drew up two designs. One was for a small-scale glider to test the idea, which he called the D.2. The other was for the full-sized powered aeroplane. In the event the glider was never built and Huntington began directly on the full-sized craft. He finished building it in 1910.^[1]

Short Brothers accepted the order to build the aircraft on 9 April 1909 and delivered it on 23 December 1909.

Huntington flew it successfully at the Royal Aero Club grounds at Eastchurch, progressively modifying it between 1910 and 1914 until it flew well.

Description

The main feature of the design was a set of three wings, each of 10 ft (3.0 m) chord, placed immediately fore and aft of each other. The fore-wing was of reduced span and the middle wing raised to give the appearance of a heavily staggered canard biplane. The angle of incidence of each plane was adjusted to provide longitudinal stability.

The outer sections of the rear wing were given a sharp downward angle or anhedral. Triangular outboard control surfaces were hinged on the diagonal to these sections and provided all the functions normally produced by separate elevator, aileron and rudder controls. When operated together they acted as elevators, while when operating differentially they acted as combined ailerons and rudders to bank the aircraft into a controlled turn.

Side curtains between the two full-span wings were initially fitted but later removed.^[2][3]

Power was provided by a single Wolesley water-cooled engine chain-driving twin propellers. These were mounted in the space beneath the upper wing and their axles doubled as twin cylindrical booms connecting the fore and aft structures.

When operating at Eastchurch in early 1910, the open fuselage structure was originally mounted on a three-wheeled chassis and skid plus a tailwheel; later the nosewheel was removed and replaced by two semicircular skids at the front. The front wing was mounted at the nose and had considerable sweep back. On the same level, at the rear end, was a wing of parallel chord, with anhedral on the outboard section. This was also split diagonally to form triangular flaps for control in roll and pitch. The top wing was mounted above the central fuselage and braced to it by struts, and to the rear wing by vertical struts at the leading edge; also by raked struts to the front where the anhedral began. The pilot was seated well forward of the biplane wings in the inner apex of the vee-shaped front wing.

In 1912 a more powerful 70 hp (52 kW) Gnome air-cooled rotary engine with single engine-mounted propeller was fitted, enabling the craft to reach 43 mph (69 km/h).^[4]

Specifications (Re-engined)

Data from Goodall & Tagg (2012)^[5]

General characteristics

• Crew: One
• Length: 50 ft (15 m)
• Wingspan: 59 ft (18 m)
• Powerplant: 1 × Gnome Rotary, 70 hp (52 kW)
• Propellers: Two-bladed

Performance

• Maximum speed: 43 mph (69 km/h; 37 kn)

Notes