The bug-eye Optica winning acclaim

Press, 4 June 1982, Page 14

The bug-eye Optica winning acclaim

By

R. A. J. ARTHUR

London Press Service

A quiet revolution started in the aircraft industry when John Edgley, a young structural engineer, set out to build an aircraft at an improvised workshop in the heart of London.

When it was finished, he packed the bits up and sent them 75 km north to Cranfield, noted for its air show and aeronautical college, where strange new flying machines cause a minimum of surprise. Optica was a new kind of aircraft, with its great in-sect-eye cabin thrust out in front to enable the threeabreast pilot and passengers to see everything on the ground below. Designed for observation roles, it looked, and was, something different — a fixed wing aircraft to compete with the helicopter: slow flying, all-seeing, but, unlike the helicopter, quiet and virtually free from vibration. It was also cheaper to ; build and fly. At Cranfield, early in 1980 and six years after the start of the project, Optica was test flown. Almost inconspicuously, it registered itself as the only single-engined modern aircraft designed specifically for its visibility, the first single-engined aircraft with a ducted fan engine and the quietest production aircraft in the world. This was an achievement not only for its boldly enterprising designer but for London’s Imperial College , which helped with the aerodynamics research.

"I looked for a gap in the market,” says John Edgley, at his country home near. Cambridge, explaining how it all began. He tried to identify some kind of aeroplane that did not exist, but for which the world was crying out.

At the 1981 Paris Air Show, where Optica had quietly replaced the helicopter as the best flying platform for photographing the show itself, John Edgley met the French chief of an oil pipeline company, who said that for 10 years he had been sketching the ideal aeroplane for pipeline inspection. Carrying the notion around with him, he was surprised to see it appear before his

eyes in the shape of Optica. The Paris showing led to an order for 25 machines from Sleigh Aviation of Australia, where shark-spotting and cattle herding were among the specialised uses proposed for Optica. The need for such an aircraft is as old as the dawn of the conservation era, when the helicopter with its big fuel demand became a strain on resources in spite of its enormous usefulness.

The slow flying, fixed-wing machine, with all-round vision, lacking the. noise and vibration that are the very symptoms of waste, is a dream-child of the conservationist.

Many people probably had that dream, but its realisation was left to John Edgley. The curious fact is that he did not set out to be an aircraft designer. A graduate in structural engineering of Bristol University, who had spent some

years in the Seychelles and in Australia on civil engineering projects, his thoughts only gradually turned to the air. His professor at Bristol had once been head of structures at Farnborough, Britain’s leading aviation development centre. In casual reminiscences about the research work the seed of interest was sown, and in 1974 John Edgley decided to study the prospects in aviation.

A small country like Britain, he reasoned, could hardly compete with lowpriced, mass-produced aircraft. It would be advisable to try for something new. Edgley and his associates considered designing a fiveseater aircraft, but for a first shot it seemed too ambitious. Then they tried a two-seater, but the popularity of the three-seat helicopter with canopy cabin gave a first significant pointer to the gap in the market.

The objective for all-round observation, pursued with complete functional logic, led to a cabin design that astoundingly mimics the insect kingdom — with its dragonfly’s eye configuration. The practical result is that the observer, photographing in any direction, finds his lens approximately at a right angle to the Perspex windows with a minimum of distortion.

This Perspex cabin tapers backwards into the centre of the fan itself. The fan therefore sucks in air unperturbed by any obtrusive wing section or by engine exhaust, for the engine lies behind the fan.

These are the factors that get rid of noise and vibration, though most telling of all is the substitution of the ducted fan itself for a propeller since most turbulence 'is at the propeller tips. The blade tips of the smaller

diameter fan have less distance to travel, hence cause less turbulence and, unlike the propeller tips, are enclosed.

The twin boom and high tail design makes for easy maintenance. Engine and fan can be lifted out from behind in a single pod which has only four attachments. Central to the design concept is the wish to combine advanced functional design with a basic simplicity. This allows a machine to operate in the lesser-developed countries.

Generally speaking, in the aircraft industry an aircraft with a cabin as wide as Optica’s 1.6 metres cannot be purchased for under $2.2 million. Yet Optica’s $113,850 price buys other advantages too.

Whereas the helicopter carries fuel for little more than three hours flying, Optica can stay aloft for 10 hours.

In the developing countries, where fuelling facilities are scarce, Optica can take off from home base, fly a few hours to some remote

frontier area, land, pick up observers, take off, carry out its patrol, touch down,'then take off again and return to base, all without refuelling. With a loiter-observation speed down to 92 km/h and a top speed of 203 km/h in level flight, it can take on many of the helicopter’s roles.

In the ease of maintenance, Optica makes only light demands. Its landing gear is mounted on rubber blocks, and the same sort of simple, robust construction throughout makes it ideal for countries where maintenance facilities are not plentiful. For instance, the design avoids a flexible coupling between the engine and fan, and there are no complicated drive shafts. The result is an aircraft that in every way satisfies the conservation era’s demand for truly economical design. So far as advanced countries like the United States are concerned, its vi-bration-free characteristics could make it the standard television flying platform for electronic news gathering, which uses helicopters now at some cost in picture quality-

By comparison with the helicopter, Optica cannot take off and land vertically but its initial cost is much lower, and fuel and maintenance costs are about 30 per cent those of comparable helicopters. The test pilot summed up its qualities in this way: “The key words are simplicity, stability, view, and quietness. The aircraft has proved easy to handle and control, being very stable and yet having good control authority.” Other pilots show a similar enthusiasm for a machine that highlights the ducted fan approach as a breakthrough in aviation.

Among roles proposed for the versatile Optica are: aerial photography, television, press reporting, security patrols, traffic watch, inspection duties over oil and gas pipelines, forestry and power lines; geological surveying, mineral ore prospecting, archaeological exploration, police duties, frontier and coast guard patrols, tourist sightseeing, game spotting, and agricultural observation.

Full-scale production is due to begin shortly at Old Sarum airfield, near Salisbury, in southern England.