If things had turned out a little differently, the Rotodyne could have been a more convenient option for short-haul flights than the regional jets that we now use.
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The Fairey Rotodyne is demonstrated in June 1958 at White Waltham near Maidenhead, United Kingdom.
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The Land Rover was a valuable export from Britain. Unfortunately, the Rotodyne couldn't.
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The term "Urban Air Mobility" (UAM) seems to have been around for a while, but actually it has only been widely used for two or three years. NASA officially recognized UAM in 2017 and requested a market study for remote or unmanned passenger and freight transportation in an urban area. Most people would probably call this the "air taxi" idea – a vision of hundreds of small, unmanned electric multicopters that take two or three passengers from nearby suburbs or urban areas to turnstiles at a speed of approximately 161 km / h.
But if things had been different in the late 1950s and early 1960s, we might have a completely different understanding of UAM – more like local transportation. We may have had a vertical take-off and landing aircraft (VTOL) with 55 passengers from city center to city center, which oscillated between urban heliports at 289 km / h.
We actually had that, there are very few people who remember. It was called the Fairey Rotodyne.
Born by grounding
Fairey Aviation was born in 1915 in a suburb in west London. While World War I was in full swing, Charles Richard Fairey, a talented young engineer at Short Brothers Aircraft, was prevented from joining the Royal Naval Air Service (RNAS) because the British Admiralty Department believed that he was an aircraft designer / – would be more useful than a (probably short-lived) pilot.
Annoyed at not being able to be among his colleagues, the 26-year-old Fairey agreed not to be upset when he received a sub-contract for aircraft production that allowed him to start his own business. Aircraft were in high demand as the newest weapon, so the admiralty agreed and in mid-1915 he was commissioned to build 12 short 827 seaplanes for the RNAS.
Fairey Aviation grew from there and produced its first internal design in 1917, the Campania seaplane carried by ships. The company continued to design and produce seaplanes, fighters, and bombers during World War II and the 1950s, including Firefly, Swordfish, and Gannett.
With peace on the horizon in the final months of World War II, the manufacturers who were building military aircraft at the time realized that there would soon be much less demand for their production. Commercial aviation was an obvious new line of business. In the meantime, the development of rotary wing flight had accelerated dramatically during the war. The Fairey competitor Westland Aircraft had started construction of the S-51 in 1947, a helicopter that was developed by the American company Sikorsky.
Like other British aircraft manufacturers, Fairey wanted a piece of this new helicopter market.
Tip Drive, Autogyros and Jets
Most of the early "helicopters" were multi-rotor machines, not the single main rotor helicopters we are thinking of now. One of the few early single rotor designs, the Brennan helicopter, began development in England during the First World War. It deviates from the complexity of most helicopters that turned their rotors by coupling them directly to an engine via chain or gear drives. Instead, its Irish inventor, Louis Philip Brennan, came up with the idea of rotating the blades with the thrust of a small four-blade propeller attached to the tip of each rotor blade.
The top propellers were driven by drive shafts that ran through a hollow tube (spar) that supported the rotor blade. These are connected to a motor below the rotor head via shafts and right-angled gears. Brennan's "Tip-Drive" helicopter was able to lift a pilot, four men and one hour of fuel, but control problems meant that he never flew higher than 3 meters. A crash in 1925 shook trust in the project, and the creation of another machine, the Autogyro, distracted Brennan's tip-drive concept.
Enlarge /. Spanish pilot Juan de la Cierva (1895 – 1936) in Hendon before flying his gyroplane or autogyro from London to Paris after the King’s Cup Air Race on September 17, 1928.
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The autogyro was designed by Spanish engineer Juan de la Cierva in the early 1920s and looked like a helicopter and an airplane together. This is because Cierva didn't design a helicopter. He tried to design an airplane that could fly at low speed without stalling.
An autogyro supports the flight by combining small wings with a freely rotating rotor that only rotates in forward flight due to the passage of air. A separate motor and propeller (in tractor or pusher configuration) provide forward thrust, and the airflow over the angled rotor blades causes them to spin and generate additional lift. Autogyros generally cannot start vertically. Because of their "autorotating" blades, however, they can make short take-offs and vertical landings.
Cierva later founded the Cierva Autogiro Company in England with the Scottish industrialist James G. Weir. Though they never really made it through the years, improvements to Autogryos by Cierva and American aircraft manufacturer Pitcarin made them popular novelties in the 1930s.
At the same time, the Englishman Frank Whittle and the German Hans van Ohain worked separately on the turbojet engine. The world's first jet plane, the Heinkel 178, first flew in Germany in 1939. Three years later, the Austrian engineer Friedrich von Doblhoff decided to combine Brennan's appealingly simple tip-drive concept with the jet engine.
The Doblhoff WNF 342 was a three-wing helicopter that used a piston engine that powered a compressor to provide compressed air. When mixed with fuel, it was led out through the rotor hub and through the three hollow rotor blades to be burned in tip-mounted nozzles, creating a rotor thrust. The rotor jets were only used for takeoff, hovering and landing.
The war stopped the development of the WNF 342, but in the following 15 years, the Fairey engineers would eventually pull together the threads of Brennans, Ciervas, and Doblhoff's work.
While the modern helicopter configuration was well established until 1946, the desire to minimize torque, vibration and load on the drive train was also known. Helicopters were amazing, but they weren't particularly reliable. Fairey recognized this as a real commercial limitation. So they set about designing something else – a compound helicopter.
Fairey was recruiting Dr. J.A.J. Bennett, who previously worked with Cierva and Weir. Dr. Bennett, using a proponent of designs that combined helicopter and autogyro features, proposed a "gyrodyne" concept. The aircraft would have a powered rotor like a helicopter, but also wing stubs and a thrust-producing propeller like an autogyro.
Driven by the same engine that powered the rotor, the starboard prop counteracted the rotor torque and provided thrust. Most of the engine power was transferred to the rotor for take-off, hovering and landing. In the forward flight it went to the propeller. The rotor then turned automatically, reducing the stress on the rotor head and gearbox while still generating lift along with the wing stubs.
Reduced rotor speed enables higher cruising speeds. Seven months after its first flight in 1947, the first of two Gyrodyne prototypes set a world speed record for helicopters flying at 108 knots (200 km / h). The aircraft made progress in testing, but a fatal crash in 1949 paused the program.
German engineers from Doblhoff were among the Fairey employees who wanted to develop further. With their encouragement, the company decided to retrofit the second Gyrodyne as a test bench for a tip-jet drive system. The rotor and the gearbox were removed and replaced by a two-bladed rotor with tip jet drive. The tip jet rotor worked by taking air from two motor-driven compressors that flowed through the rotor blades alongside kerosene, which was then mixed and burned by the jet.
Like the Gyrodyne, the rotor was driven to take off and land. In the forward flight the jets were switched off and the plane flew as a gyrocopter. The forward thrust and yaw control was carried out via motor-driven thrust propellers on the wing stubs. The Jet Gyrodyne, as a gyrocopter, was only able to maintain a level flight for a short time, but his promise convinced Fairey to do two more tip-jet designs. The first was a small helicopter with a pure tip-jet drive called the Fairey Ultralight Helicopter. The second was the ambitious Rotodyne.
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