The Heli-Liner

While Fairey was proving the feasibility of the Gyrodyne and Jet Gyrodyne, futurists in America, Europe, and the UK were imagining airliner flight with helicopters. Short-range city-to-city passenger transports that could land downtown without need for an airport were recognized as potential money-makers by airlines including British European Airways (BEA), which solicited proposals for a short haul heli-liner in 1951.

Fairey submitted its own heli-liner proposal to BEA and to the UK Ministry of Supply, which planned to award a contract for a prototype aircraft combining the VTOL capabilities of a helicopter, the speed of a gyrocopter, and the passenger capacity (40 seats) of an airliner. Though Fairey proposed several designs over the years, its Rotodyne proposal won the contract (which called for a cruise speed of 150mph and a range of 250 nautical miles) in 1953.

The "Rotodyne Y" looked like a twin-turboprop airliner with short wings and a huge four-blade tip-jet rotor on top. Like the Jet Gyrodyne, its rotor would be powered-up for landing and takeoff; in cruise flight the jets were switched off and the blades autorotated, producing lift along with the wings. Two 2,800hp (2,089kW) Napier Eland N.E.L.3 turboprops provided thrust in cruise. The transition between helicopter and autogyro flight took place at about 60mph.

In helicopter mode the engines supplied power to two compressors, which fed air (and fuel) to the combustion chambers of the tip jets through each of the 90-foot (27.4m) rotor blades. Each engine supplied air for a pair of opposite rotors. If one turboprop failed, the pair of tip jets supplied by the remaining engine could still spin the rotor. In low speed flight yaw was controlled by varying the turboprops' propeller pitch via rudder pedals.

Reg Birkett/Keystone/Hulton Archive/Getty Images

SSPL/Getty Images

The Rotodyne's boxy 59-foot (18m) fuselage could accommodate passengers or cargo that could be loaded through clamshell doors in the tail. Triple vertical tails gave the Rotodyne directional stability in cruise but folded after landing to accommodate the droop of the halted rotor blades. On November 6, 1957, the Rotodyne made its maiden flight, piloted by Fairey test pilots, Squadron Leader W. Ron Gellatly and Lieutenant Commander John G.P. Morton. In April 1958, it made its first successful transition from vertical to horizontal and then back into vertical flight. As flight testing continued, the prototype demonstrated what it could do.

The Rotodyne was publicly displayed at the renowned Farnborough Air Show in 1958 and '59, impressing both commercial and military observers. Fairey emphasized its safety—it could hover with one engine shut down, and the prototype demonstrated several airplane-like landings as an autogyro.

On January 5, 1959, it blew away its speed requirement, setting a world speed record in the "convertiplane" category, at 190.9mph (307.2km/h), over a 60-mile (100km) course. In June of that year, the Rotodyne flew a load of passengers from Heathrow Airport to the 23rd Aeronautical Salon in Paris with stops in Brussels and Issy Heliport in Paris. It cruised at 180mph (289km/h).

Fairey flight test engineer (later chief engineer for Westland) David Gibbings recalled in a BBC documentary called The Golden Age of Flying how effortlessly the Rotodyne flew: "It leaped off the ground and into transition as if it had done so a thousand times. You didn't feel it was a faltering, ‘Let's see how it goes this time chaps' affair. It was confident in the extreme."

In Paris, it was met with interest by American firm, Kaman Helicopters and Japan Airlines. BEA had already announced that it was interested in purchasing six aircraft, with a possibility of up to 20. The RAF placed an order for 12 military transport versions. After calculating that a larger Rotodyne could operate at half the seat-mile cost of helicopters, New York Airways signed a letter of intent to purchase five with an option of 15 more, though it wanted a 60 passenger version that Fairey would seek to develop as the Rotodyne Z.

It seemed the Rotodyne was on its way.

The way but not the will

Money was always tight for Rotodyne development, with Fairey's own resources limited by fewer defense contracts and diminished government financial support in the mid-1950s. Noise was considered a problem, too. With the tip jets in action in VTOL flight, the Rotodyne was loud, reportedly 113dB at 600ft (180m) away. Gibbings told the BBC that working at Fairey's White Waltham ground-test facility located on one corner of the airfield there: "It was quite a fun place to work because [the Rotodyne] made so much damn noise they kept you miles away from anybody."

BEA was concerned that the public would not accept the noise. Fairey, and later Westland, worked on dozens of tip-jet silencer designs, reducing the volume to 96dB with a projected further reduction to 95dB at 200 feet (61m). Fairey even conducted test flights over central London with several landings and departures at Battersea Heliport without noise complaints. Like present day UAM developers, Fairey claimed average city noise canceled out maximum Rotodyne noise, which lasted only during takeoff and landing.

But the Rotodyne had a bigger problem—politics.

The drive to control Britain's economy by nationalizing industries from mining and utilities to healthcare, which began with Labour Prime Minister Clement Attlee in 1946, continued through the 1960s. At the beginning of 1960, there were more than 20 aircraft manufacturers in the UK. By 1961, the government had forced them to consolidate into just three. Fairey was absorbed by Westland which became Britain's only helicopter maker. Westland planned to continue the Rotodyne project, but government defense and civil support was largely withheld. Potential airline and foreign buyers lost confidence in the yet-to-be-built Rotodyne Z, and in February 1962 the program was ended.

Classified as government property, the Rotodyne Y prototype was mostly destroyed. A portion of the fuselage, rotors, and rotorhead mast remain on display at a museum in Weston-super-Mare.

The Rotodyne lives?

If not for social policy, could the Rotodyne have succeeded on a technical and cost-per-seat basis? "Definitely," says Mike Hirschberg, Director of the Northern Virginia-based Vertical Flight Society (VFS). He acknowledges that the larger Rotodyne Z would have required more engineering and investment but adds that it was decidedly achievable.

Today, VFS is active in highlighting the merits of the approximately 215 known eVTOL (electric VTOL) concepts being studied around the world. More than a dozen are in flight testing including Uber's all-electric unmanned air taxi being developed by five manufacturer partners for "regular urban eVTOL transport by 2023." The desire for pure electric power by Uber and others has driven the mass air taxi strategy. As Hirschberg told Ars, the energy density limits of batteries constrain the possibility of large eVTOL aircraft. And yet, the promise of Rotodyne was its cost-per-seat basis, estimated as low as $0.04/seat-mile in 1960.

Skyworks



Skyworks

Even leaving infrastructure costs aside, small eVTOL air taxis will struggle to match the Rotodyne's cost efficiency—unless they can stretch their energy further. "There are companies today who are proposing similar aircraft to the Rotodyne," Hirschberg observes. Uber partner Jaunt Air Mobility is building a gyrocopter-like concept called Reduced rotor Operating Speed Aircraft (ROSA). Another firm, Skyworks Global, has a rotodyne-type design called Vertijet, a combination bizjet/gyrodyne aimed at the UAM and military markets.

The project grew out of DARPA's frequently forgotten early-2000s Heliplane program which sought a long-range, light jet-sized compound VTOL aircraft intended to be faster than helicopters. The program was aborted in 2008 but former DARPA program manager Don Woodbury tells Ars the Rotodyne inspired its development. "If [the Rotodyne] had made it into commercial use, our whole notion of inter-city transport would be far different than it is today. The Rotodyne would've been a formidable competitor in terms of cost and performance."

Woodbury is now chief technology adviser at Skyworks Global where he works on the Vertijet and a potential new Gyroliner. He remains an admitted Rotodyne enthusiast. "I thought it was this forgotten branch of aviation and that it never really had its chance," he says. But nearly 60 years after the Rotodyne program ended, the idea remains very much on the mind of today's transportation engineers.