Builder:Ivan Shaw (Aviation Composites Ltd.)
Type: twin-engined two-seat canard pusher sportsplane
Powerplants: 2 x 75-77 hp 3-cylinder
Significant date: 1988 (first flight tests), 29 June 1989 (first flight in definitive configuration)
The Twin-EZ was developed and built by Mr. Ivan Shaw, a British science school teacher who basically dreamed of modifying his Rutan pusher in the image of the futuristic Beech Starship. The Twin-EZ started life as a homebuilt Rutan VariEze built in 1980-81. "After 350 happy hours flying", Shaw explained, "I decided to convert it to a Long-EZ then, inspired by Starship, got carried away with twin engines and retractable gear." Thus was born the project initially referred to as the Twin Speed.
For his new twin-pusher, Shaw initially planned on using two 50 hp Lotus rotary engines engines. According to him, twin pusher engines and a retractable undercarriage should boost the Long-EZ's cruise speed to 200 m.p.h. and increase range to 2,000 n.m., offering 50 m.p.g. fuel economy. "No other light aircraft will be able to touch it," claimed Shaw, a self-confessed "eyeball engineer" who aimed to fly his home-built late in 1985 when a pair of Lotus microlight engines would become available.
Shaw complained that the standard Long-EZ was a "high technology airframe powered by a low technology engine". The recommended engine was a 100 h.p. unit made by Rolls-Royce, Continental, or Lycoming, while Shaw claimed a pair of 50 h.p. Lotus engines weighed 701 lb. less than either of the other units and burned 20 per cent less fuel. He built a bracket which allowed the pair to be attached to the standard engine mount on the rear fuselage, each engine sitting just 31 in. from the fuselage centre line. Electrical systems could be run from either engine, offering "complete redundancy". "I can't see why anyone would fit a Lycoming when the Lotus engines become available, offering twin engine reliability," he added.
However, for Shaw, who had worked with Lotus and Rutan on the Microlight aircraft, Colin Chapman's untimely death also signified the end of all aviation activity for Lotus, engines included. Development of the Lotus engine type was stopped, and therefore none was ever installed on the Twin-EZ. As a result Shaw decided to modify the aircraft with larger Long-EZ wings to accommodate two 77 hp Hewland HAE75 three-cylinder two-stroke reciprocating engines (initially developed by Mike Hewland for the ARV Super Two aircraft), installed in a pusher configuration.
Shaw's other modification was to fit a fully retractable undercarriage. The main gear was a retractable unit of Shaw's own design that tucked into the wheels aft through 115° to where the engine used to be, and was powered by hand hydraulic. This carried a 301 lb. weight penalty over the fixed undercarriage, but reduced drag and so offered the prospect of the major speed increase Shaw was predicting. Empty weight was predicted to be 800 lb. and the first flight was to be made within six weeks of engine delivery.
In its definitive configuration, the Twin-EZ was first flown on June 29, 1989, and was demonstrated days later at the UK Popular Flying Association's annual rally at Cranfield Airport. Shaw commented that the new aircraft flew "superbly, just like the Long-EZ", with even less vibration and easy control on even one engine only.
The Twin-EZ was soon used as test-bed for the Norton-Wankle NR642 rotary engines, each unit being mounted pusher-style at the wing trailing edge and using two pusher props of 53 in diameter. The Norton rotary engine had already been tested in 1987 in an Aviation Composites Mercury, a local derivative of the Microlight developed at Scaled Composites. The advantages of the rotary Norton over the Hewland engine were said to be a lengthy overhaul interval and increased power. The latter would improve performance and allow a higher gross weight. The Norton engine developed 90 h.p. compared with the Hewland's 75 h.p., and was claimed to be extremely light for its power output owing to constructional simplicity. Thus powered, the Twin-EZ attained a cruising speed of 175 knots.
The history of the Twin-EZ after that is not quite clear, but the aircraft is still on the British register to this day, and now belongs to Anthony Malcolm. Chances are it has long been reverted to a more or less standard Long-EZ configuration.
Population: 1 (c/n 39; s/n PFA 074-10502) [G-IVAN]
Many thanks to Walter van Tilborg for providing the basis for this article.
More about Ivan Shaw
Ivan Shaw was the general manager of Aviation Composites Ltd, a former branch of the Lotus car company. After Shaw set up his own business in July 1985, Inav (Innovative Aviation, Ltd) — a new wholly owned subsidiary of Britain's Aviation Composites — established to purchase the assets of Monnett Experimental Aircraft, Inc (MEA), he eventually met with success when he launched the Europa light aircraft in the late 1990s, arguably the most successful kit aircraft manufacturer in the world, which itself became the basis for the Liberty XL-2, testifying to his long-term work relationship with Scaled.