FAIREY   ROTODYNE

 Ante el resultado positivo del Jet Gyrodine, la propuesta del doctor J.A.J. Bennet y del capitán A.G. Forsyth, formulada en 1947, de construir un gran convertiplano, parecía prometedora. En diciembre de 1951 la British European Airways solicitó un aparato de 30-40 plazas para rutas cortas y medias, y Fairey presentó una propuesta que correspondía mas o menos con sus ideas. Fue aceptada, y en 1953 el Ministerio de Abastecimientos le otorgó un contrato para un prototipo experimental.

Se montaron andamiajes de prueba en White Waltham y Bescombe Down, donde el sistema de ensayos constaba de rotor principal, las dos turbinas, alas, etc., y se instalaron los controles en un compartimiento situado en la posición aproximada del morro. Se realizaron pruebas exhaustivas mientras se construía el prototipo. El Fairey Rotodyne realizó su primer vuelo como helicóptero el 6 de noviembre de 1957 y la primera transición a vuelo horizontal tuvo lugar a mediados del mes de abril del año siguiente.

El Rotodyne tenía un fuselaje de concepción ortodoxa de sección cuadrangular con alas cortas y rectangulares en las que iban montadas las turbinas Eland. El tren de aterrizaje triciclo se plegabla en el interior de las góndolas de los motores. Una doble deriva, luego completada con otra central , estaba montada en los extremos del plan o de cola, de planta rectangular implantado en posición alta. El despegue en vertical se lograba gracias a un gran rotor cuatripala, que era alimentado con aire comprimido purgado de las turbinas y mezclado con combustible. Posiblemente eran estatorreactores. Cada turbina alimentaba dos palas opuestas con el fin de evitar asimetrías en caso de falla de un motor.

El 5 de enero de 1959 el Rotodyne batía el record de velocidad para convertiplanos sobre circuito cerrado de 100 Km, dejándolo en 307,2 Km/h. Dicha marca no fue batida hasta octubre de 1961, por el helicóptero soviético Kamov Ka-22.

Las cosas parecían ir bien para el Rotodyne: en 1958 la Kaman Aircraft Corporation adquirió la concesión para USA, con opción de construirlo con licencia. Okanagan Helicopters de Vancouver, Canadá, deseaba tres y Japan Airlines estudiaba su empleo para servicios locales. Pero el mayor cliente potencial era la New York Airways, que se unió a Kaman para presentar una demanda de cinco aparatos con opción de diez, a entregar en 1964. Estos cinco últimos deberían ser una versión mejorada de 54-65 plazas y turbinas Rolls-Royce Tyne.

 The initial work accomplished by Fairey with the unloaded-rotor concept was accomplished in the early 1950s with an earlier program, the Gyrodyne, which was powered by a single reciprocating engine. The main emphasis of this development was a commercial application with the design of an intercity rotorcraft.

The emphasis behind the development was the belief that this concept could overcome a number of the inadequacies of standard helicopters, i.e. inadequate payload, insufficient range, mechanical complexity, excessive vibration, and the inability to remain aloft in case of powerplant failure.

With the Rotodyne concept, a pair of engines each drove a single propeller which provided the propulsion for horizontal flight. The engines also supplied air to a compressor that supplied air to jets that were located on the rotor tips, the power from which provided the hovering capability of the craft. This energy provided aerodynamic lift by whirling the overhead rotor, exactly the same concept as with a standard helicopter.

Once the desired altitude was acquired through this process, the total power of the engines was diverted to driving the propellers. Also, the tip jet operation was ceased and the lift for horizontal flight was obtained by the propeller and the stub wings upon which the engines were mounted. A feature of the design was that adequate single-engine performance was provided following an engine failure at any flight speed.

Transition from vertical-to-horizontal flight, with the rotor autogyrating, was accomplished on April 10, 1958.

The pair of Napier powerplants provided an impressive total of 7000 horsepower with a gross weight of 17500kg. With a payload of 4500kg, the plane was capable of a range exceeding 650km at up to 270km/h. Impressive performance indeed! It's easy to understand why Fairey was so confident that it had a real winner with the Rotodyne.

The technique, though, of the engines serving a dual purpose was the same as the Gyrodyne system, each driving a propeller and providing the compressed air for the pressure-fed wingtip jets. To provide an idea of the size of this machine, vision the fact that the rotor was 27.4m in diameter. For safety aspects, two opposing blades were powered by each engine in case of engine failure. An onboard hydraulic system provided for cyclic pitch control.

The Rotodyne was extremely large, with a cabin volume of 93m³ cubic feet. The logistical attributes of the machine were considerable with rear clam-shell doors allowing the loading of large motor vehicles. A forward-located door permitted simultaneous entry and exit of passengers, which would have allowed a quick turn-around in a commercial airline operation.

It was estimated that a passenger load of as many as 48 could have been carried by the Rotodyne. That passenger compartment was 14m long, 2.4m wide, and 1.8m in height.

Like other compound-type VTOL vehicles, had the Rotodyne been minus its trapezoidal rotor-mounting pylon, the vehicle would have looked much like a conventional aircraft. The rotor was mounted at a lofty 6.70m above the ground, providing an idea of the size of the Rotodyne.

The design sported a high wing and a twin-tail configuration. That tail design was interesting in that the lower tail surfaces were oriented straight down, while the upper surfaces were canted at about a 45 degree angle.

The speed capability of the Rotodyne of about 320km/h made it slower than traditional transports, but it could make up for that deficiency with the capability of landing on downtown heliports atop buildings and getting business people to their final destination much quicker. Another attractive aspect of the Rotodyne for this commercial application was the fact that it was projected to have a range of up to 640km at gross weight.

The Rotodyne was subjected to a vigorous flight test program of over 350 flights, more than half of them demonstrating 200 hover-to-vertical flight transitions.

The production Rotodyne was to be a somewhat larger vehicle with a rotor diameter of an amazing 27m with a gross weight of 30 tons. The propulsion systems would be changed to Rolls-Royce Tyne engines.

There was serious consideration for production of the craft, both domestically and in the United States. That possibility came to light in 1958 when a license agreement was reached between the Kaman Aircraft Corporation (USA) and Fairey. The agreement provided for the manufacture of the aircraft in the U.S. by Kaman.

Characteristics
Características

Information
Información

Characteristics
Características

Information
Información

  2 Napier
Eland NEI.7

 2 / 30-40

2800 SHP each

Kg

Ft

14900 Kg

Ft

 161 Kts

Ft

Kts

378 NM