Fairey Rotodyne E-Book

David Gibbings

• Herausgeber: The History Press
• Kategorie: Lebensstil
• Sprache: Englisch

Veröffentlichungsjahr: 2011

Beschreibung

The Fairey Rotodyne was a large British compound helicopter designed and built by the Fairey Aviation Company and intended for commercial and military applications. It was considered to be one of the iconic aviation projects of the 1950s/60s and a bright future was planned for the aircraft. Widely accepted to be a revolutionary design, it was economically viable, fast and capable of vertical take-off and landing from city centre heliports. However, despite the proven feasibility of this bold concept, the Rotodyne project was terminated in 1962 due to escalating development costs and unresolved technical issues. This book seeks to fill a gap in aviation literature on the history of the Rotodyne, an aircraft ahead of its time. Winner of Hampshire Libraries Special Collections Award 2010.

Leseprobe

Contents

Foreword

Definitions

Introduction

one BEFORE THE ROTODYNE

two THE ROTODYNE THAT WAS BUILT AND FLOWN

three THE ROTODYNE THAT MIGHT HAVE BEEN

four THE ROTODYNE FIFTY YEARS ON

five RENAISSANCE

Appendix 1 – The Pilot’s Viewpoint

Appendix 2 – A Picture of Rotodyne

References

John Fairey 1935–2009

Foreword

Most people remember their first flight in a helicopter. I certainly do – no clockwork mouse of a helicopter for me. My first flight in a rotorcraft was in the Fairey Rotodyne, and even after a lifetime spent flight-testing helicopters and aeroplanes, it still remains one of the most adventurous and exciting of all those various aircraft with which I became involved.

This book has grown from a lecture request from the Society of Flight Test Engineers, which was delivered in Berlin in 1994, and subsequently enlarged, to be offered as the forty-fourth Cierva Lecture, presented to the Royal Aeronautical Society in London, in 2003, the year in which we celebrated ‘100 Years of Powered Flight’. Now we have just marked ‘100 Years of Aviation in Britain’, and the Rotodyne, having played a significant part in both events, deserves its place in history.

In 2007, I was asked to repeat the lecture as part of a celebration commemorating the first flight of the Rotodyne, in 1957, and it occurred to me that nobody has produced a book about this exciting aircraft in the intervening fifty years.

Here I will confess that I am very self-conscious of the fact that my personal involvement in the programme was as a very junior member of the team, joining towards the end. I have, however, been well placed in having access to what archive material is still available at Yeovil, and it is my hope that those who played a greater part in making this history will forgive my audacity.

As with all such books, there are a great number of individuals and organisations who deserve my thanks. Of these, I feel I must start with AgustaWestland, which is the current identity of my erstwhile employer, Westland Helicopters, and of the earlier Fairey Aviation. It is from this group that I was able to acquire the data, drawings and photographs necessary to compile this record, and the freely given permission to publish that has made it all possible.

My use of the Fairey logo on the cover gave me a surprise. I found it hard to establish who has ownership of this design, and my investigations led me to the General Dynamics Corporation, who may have inherited it through their involvement in Fairey Hydraulics. I was given the permission I required, although GD remains uncertain of the precise ownership. For myself, I thank them and trust that anyone else who may lay claim will appreciate that my request, which was made out of courtesy, also applies to them.

Flight International was, indeed, generous in granting permission to use their cutaway drawing, photographs and the article by Ron Gellatly, without any reservations. My negotiations with Andrew Costerton left me with a warm feeling that I was dealing with friends. It was no less the case when I sought permission to use material from Aeroplane; Michael Oakey was generous and accommodating, and both these great journals have my sincere admiration.

Producing art work to the high standards set by The History Press would have been considerably harder without the assistance of Doug Lloyd, who patiently accepted all my demands in spite of his own punishing work schedule. Doug is also responsible for the striking cover design; I know that you should not judge a book by its cover, but I can only hope that the content fulfils the promise implied by Doug’s work.

The AgustaWestland photographic group deserve a special mention for the way in which they dealt with the numerous old negatives I presented them with. It is due to their efforts that there are several photographs, hitherto unpublished, that can now be seen in this book.

The Carter Aircraft Corporation and Groen Brothers Aviation of America are two companies who have picked up the challenge, and are currently working on projects that incorporate some of the technology that distinguished the Rotodyne. Both groups were extremely helpful, and I wish them the success that was so carelessly abandoned by faint-hearted officialdom so long ago. Remember: ‘Fortune favours the brave!’

I have carefully avoided naming individuals within the book, on the grounds that the success of any venture relies upon the collective effort of all concerned.

For my own venture in the form of this book, I must acknowledge the help and support of friends and colleagues, many of whom are unaware that they have done anything: Fred Ballam, David Balmford, Tony Bamford, Mike Breward, Peter Bunniss, Bruce Charnov, Andrew Costerton, ‘Sonny’ Darlington, Jack de Coninck, Pat Douneen, John Elver, John Fairey, John Firmin, David Groen, Mike Hirschberg, Dr G.S. Hislop, Anita Infante, Derek James, Alan Jeffrey, Doug Lloyd, Michael Oakey, Tony Pike, Norman Parker, Simon Prior, Ted Roadnight, Vic Rogers, Geoff Russell, Jim Schofield and John White. I am sure there are others, who have my apologies, but then, I am of an age now that I can claim ‘a senior moment’, so I am sure they will forgive me.

I feel that I must pay tribute to the memory of Dipl Ing August Stepan, for whom I worked during my time with Rotodyne. Working for ‘Steppie’ gave me a link with the past (he flew the Doblhoff jet helicopter on its first flight in 1944), and what I learned from him and his team steered the rest of my career in aviation.

The Rotodyne story is a tale of vision, ingenuity, achievement, unfulfilled promise and lost opportunity. What was achieved has stood the test of time; what was carelessly lost has given us cause to regret, and to wonder, it couldn’t happen again, could it?

Definitions

HELICOPTER

A rotorcraft, which throughout its flight derives substantially the whole of its lift, control and translational thrust from a power-driven rotor system, whose axis (axes) is (are) fixed and approximately perpendicular to the longitudinal axis of the rotorcraft.

GYROPLANE (Autogiro)

A rotorcraft which, throughout its flight, derives the whole, or a substantial part, of its lift from a freely rotating rotor. The gyroplane provides propulsive power through its propeller, pushing or pulling (configuration dependent) the rotor through the air to sustain level flight or climb.

Note: Throughout this book the term ‘autogiro’ has been presented with the spelling used and originally patented as a Trade name by Cierva. It would be quite correct to use the term ‘autogyro’ but the alternative usage has been deliberately adopted as a tribute to Juan de Cierva, to recognise his status as a rotorcraft pioneer.

COMPOUND HELICOPTER

A rotorcraft which, in vertical or hovering and low speed horizontal flight, derives substantially the whole of its lift and control from a power-driven rotor system, whose axis (axes) is (are) approximately perpendicular to the longitudinal axis of the rotorcraft during such vertical or hovering flight, and in translational flight may derive a proportion of its lift, forward thrust or control from the embodiment of wings and/or propulsion systems.

CONVERTIPLANE

A rotorcraft which is capable of conversion during flight, so that lift is substantially or totally transferred from the rotors to other lifting devices such as fixed wings. A convertiplane will either incorporate a propulsive system to provide forward thrust, or may, as in the case of a tilt-rotor machine, re-configure the rotor to accept the role of a propeller.

AUTOROTATION

Autorotation may be defined as the condition of flight where the lifting rotor is driven in rotation by air forces, with no power being applied through the rotor shaft. Without power applied to the rotor, a conventional helicopter can be configured to operate in an autorotative descent, producing a power-off, manageable glide slope.

COLLECTIVE PITCH

Collective pitch is a process whereby incidence change is applied to all blades simultaneously, thereby providing a change in lift for the helicopter. This is achieved by movement of the collective lever.

CYCLIC PITCH

Cyclic pitch is the process whereby incidence changes can be applied to individual blades, in a cyclical manner, as they rotate around the azimuth. By this means the blade pitch can be made to vary around the rotor disc, effectively tilting the blade tip path plane, and thus the thrust vector. Control is achieved by movement of the cyclic control column, which allows the pilot to fly the helicopter in any chosen direction.

Introduction

The concept of the rotorcraft as a flying machine is as old as aviation itself. Indeed, the well-publicised studies by Leonardo da Vinci (1452–1519) are still regarded as the first serious attempt to consider the rotor as a practical means of achieving flight, and his drawings are frequently reproduced to symbolise the historical concept of the helicopter.

In fact, being an artist myself, I like to imagine that Leonardo was in his studio, explaining his idea to his model, Mona Lisa, as he worked, and that maybe this is the reason for her smile – she had just been told about the helicopter!

With the Industrial Revolution came the realisation that sustained flight was achievable. Most of the activity centred around wings and propellers, and the use of rotors as a primary means of achieving lift featured in many of the ideas, but, in general, the concept of the helicopter, capable of hovering and landing on a fixed point, was not fully appreciated.

Once steam power became available, inventors began to realise that the power to fly was within their grasp. But it was the invention of the internal combustion engine that really made it all possible.

The ‘Miracle at Kitty hawk’, as the Wright brothers’ series of short flights in 1903 can rightfully be described, gave the world powered flight. But flight was still only achievable after a take-off run, or by means of some launching device to achieve flying speed; vertical take-off and landing proved to be illusive. Within four years of those first faltering steps into the air, several attempts were made to build rotorcraft. They were yet to be called helicopters.

Cierva’s autogiros brought things a little closer, and unlocked the technology that made it possible for a rotorcraft to sustain flight and control through its rotor.

By the end of the Second World War helicopters were a definite reality. Not only was vertical take-off and controlled hovering achievable, but machines with this unique capability could be produced in quantity at an acceptable price.

Igor Sikorsky summed up the importance of the ability to hover when he stated that, ‘If you are in trouble anywhere in the world, an airplane can fly over and drop flowers. A helicopter can land and save your life.’

With the war over, all thoughts turned to peaceful applications for the large aviation industry, which had been built up for wartime production. The helicopters of the day were neither large enough nor fast enough to be commercially viable for airline use. Only by applying a combination of available helicopter and aircraft technology did it seem possible to produce a vertical take-off airliner which might hold its own in the competitive airline market. The stage was set for the Rotodyne.

Rotodyne was a large compound helicopter, designed and built by the Fairey Aviation Company in the late 1950s. It was a bold concept, intended for production in the form of a 60,800lb, 27,579kg fifty-seven-seat VTOL airliner; and an even heavier version for military use, both of which combined helicopter and gyroplane technology to achieve forward speeds in excess of 200mph/321.87kph.

The most significant innovation in its design was the use of tip-jets. This book traces the origins of Fairey interest in tip-jet drive and the development of the successful 33.000lb/14,969kg, forty-seat demonstrator, which flew in 1957, and which, in the course of a four-year flight programme, proved the feasibility of the concept, and achieved all its experimental objectives.

When the Rotodyne project was terminated, in 1962, work was well underway on the design of the production aircraft; metal had been cut, a full-sized mock-up fuselage was built and development tests with the enlarged tip-jet system were in hand.

Because government finance and technical support had been involved throughout the programme, the prototype, hardware and data, were all deemed to be ‘government property’, and the disposal of such assets rested with ‘officialdom’.

The end result was that the prototype was cut up and sold as scrap, and the design and development data was allowed to be carelessly dispersed, thus depriving the nation of valuable intellectual property.

A few years later, a similar fate befell the TSR-2 supersonic strike aircraft, and such activity has subsequently been held to be typical of British official thinking.

one

BEFORE THE ROTODYNE

The process whereby a helicopter rotor is driven by means of power units attached to the blade tips has always attracted rotorcraft designers. The advantages are obvious; by driving the rotor from the blade tips there is no resultant torque generated by a driven shaft, dispensing with the need for a gearbox between engine and rotor or any Yaw control system, such as a tail rotor.

Dispensing with the need for a mechanical drive system incorporating gearboxes offers the opportunity for substantial weight saving, and elimination of the tail rotor removes one of the helicopters most vulnerable features.

W.H. Phillips (1842)

As early as 1842, W.H. Phillips is reported to have flown a 2lb/1kg model helicopter, driven by steam effluxes from the blade tips, achieving limited success. Power was generated by burning a mixture of charcoal, gypsum and nitre (which, in the appropriate proportions, would produce gunpowder!).

Philips was a gentleman inventor who lived in Nunhead, in the Southwark area of south-east London, and is believed to have carried out this experiment on Primrose Hill.

The inventor described the event as follows:

All being arranged, the steam was up in a few seconds, when the whole apparatus spun around like a top, and mounted into the air faster than a bird. To what height it ascended I had no means of ascertaining; the distance travelled was across two fields, where, after a long search, I found the machine minus its wings, which had been torn off in contact with the ground.

Reports of this flight vary as regards size and distance flown. There are no technical records of his work, and no record of a patent application, leaving it almost to the level of folklore, bereft of any formal recognition. If authenticated it would have been the first recorded powered flight, some six years before Stringfellow (1848). It would also have been the first recorded use of tip-jet drive, and the first successful steam-driven helicopter model.

It was reported that a replica of the Phillips model was placed on show at the exhibition held by the Royal Aeronautical Society at the Crystal Palace in 1868.

Louis Brennan (1924)

Brennan was, in fact, an Australian by birth, who established his reputation as an armaments engineer, with considerable success in torpedo design, and also by designing a gyro-stabilised monorail with military applications. As early as 1915 he had approached the War Office with proposals to produce a helicopter, and, to this end, a secret patent was taken out in his name.

The Brennan helicopter was achieving some success when it was discontinued by the Air Ministry in favour of Cierva’s autogiros in 1926.

It was 1919 before any work commenced on the helicopter project. The Air Ministry established Brennan at Farnborough with all the facilities of the Royal Aircraft Factory at his disposal.

The Brennan helicopter was based around a rotary frame carrying two blades, driven by four-bladed propellers at the rotor tips. Power was provided by a single, horizontally mounted, Bentley BR 2 rotary engine of 230hp driving the two propellers through a gearbox, via shafts running the length of the blades.

The rotor diameter was 61ft/18.5m, and the blades had a chord of 6ft/2m. The structure rotated at 50/60rpm, and the all-up weight was 2764lb/1256kg. Brennan also designed an engine starting system for the aircraft.

The first flight took place in May 1924, piloted by R. Graham, who, like many of the early rotorcraft pilots, was not a professional aviator but an engineer who had ‘greatness thrust upon him’. Subsequent flights consisted of brief hovers and limited transitions into low-speed forward flight. In the course of the two years that followed, over seventy flights, averaging three minutes each, were carried out, and significant progress was made in achieving stability and control.

The project was discontinued in 1926, upon the recommendation of the Air Ministry Aeronautical Research Committee, who saw no future in helicopters of the Brennan type, and advised that future rotary wing activities should be concentrated upon gyroplanes, such as Cierva’s ‘autogiro’, which by this time was demonstrating spectacular success.

Brennan tried in vain to get the decision reversed. In his letter to the Air Ministry he said ‘That the helicopter must and will come, I am now more convinced than when I started, and it is irresponsible for anyone to impede it’.

There were other attempts to use tip-drive:

Victor Isacco (Italy, 1926)

Isacco received support from the Air Ministry Directorate of Scientific Research, and accordingly placed a contract with Saunders-Roe to build a prototype of his machine ‘Helicogyre No.3’.

The four-blade rotor was driven by four Bristol Cherub engines mounted at the blade tips, and a fifth engine was mounted in the nose of the aircraft to provide forward thrust. The finished aircraft was delivered to the Royal Aircraft Factory at Farnborough, but was found to be mechanically complex and unreliable, and never progressed beyond attempts to ground run.

Maitland Bleeker (USA, 1930)

In 1930, Maitland Bleeker, working with the Curtiss Company, built a tip-drive helicopter, where the rotor was driven by four propellers mounted at the blade tips, powered by a single engine mounted in the fuselage. The drive and control systems were complex, and although some ‘uncertain’ hovers were achieved, the project was abandoned at an early stage.

In the event, the main stream of helicopter development progressed along entirely different paths, the most familiar being the single main rotor, with torque offset by a smaller tail rotor that also provides yaw control, but the concept of tip-drive had been demonstrated and would be re-visited as technology progressed.

Juan de la Cierva (1926)

Before considering the Rotodyne, which was a compound helicopter capable of conversion to a gyroplane mode of operation, it is necessary understand some of the technology it utilised. Fundamental to its success was the ability to shut down the power to the tip-jets, allowing the rotor to autorotate, so that all the power from the engines was available to drive it through the air, the aircraft thus becoming a large gyroplane or ‘autogiro’.

Juan de la Cierva started building aircraft as early as 1912, and in 1919 he turned his attention to the use of windmills, or rotors, as a means of sustaining lift at low speed. All aeroplanes are at risk of stalling, whereby they lose lift altogether. Indeed, it has always remained a primary cause of accidents, ‘Watch your airspeed!’ being the most common command given, with varying levels of urgency, by flying instructors since flying began. Cierva set out to produce a flying machine capable of flying at very low speeds, possibly eliminating the risk of stalling altogether.

In order to achieve this, he utilised the ability of the rotor to autorotate, whereby, at a suitable pitch setting, a rotor will continue to rotate without power, sustained by the torque equilibrium of the lift and drag forces acting on the blades. This phenomenon was already known, and in most modern helicopters it is available as a safety feature to allow controlled descent in the event of engine failure. With Cierva’s gyroplane, the rotor was drawn through the air by means of a conventional propeller, with the result that the rotor generated sufficient lift to sustain level flight, climb and descent.

Before this could be satisfactorily achieved, Cierva experienced several failures, primarily associated with the unbalanced rolling movement generated when attempting take-off, due to asymmetry of lift between the advancing and retreating blades. This major difficulty was resolved by the introduction of the flapping hinge, whereby the blades, when subjected to such forces, could rise and fall accordingly, reducing the rolling force.

In January 1923, Lt Gomez Spencer flew Cierva’s first successful autogiro at Getafe military airfield, near Madrid.

All Cierva’s pioneering work was carried out in his native Spain. In 1925 he brought his C.6 to England and demonstrated it to the Air Ministry at Farnborough. This machine had a four-bladed rotor with flapping hinges, but relied upon conventional aircraft controls for pitch, roll and yaw. It was based upon the fuselage of an Avro 504K aeroplane; initial rotation of the rotor was achieved by the manual tension of a rope passed around stops on the undersides of the blades.

The Farnborough demonstration was a great success, and resulted in an invitation to continue work in the UK. As a direct result, the Cierva Autogiro Company was formed the following year. From the outset Cierva concentrated upon the design and the manufacture of rotor systems, relying on other established aircraft manufacturers to produce the airframes, predominately the A.V. Roe Company.

The Avro-built C.8 was basically a refinement of the C.6, with the more powerful 180hp Lynx radial engine, and several C.8s were built. The C.8R incorporated drag hinges, as it was found that the presence of flapping hinges caused blade oscillation in azimuth, giving rise to high stresses with the risk of blade failure. This brought on other problems, such as ground resonance, for which friction type drag dampers were fitted.

As the resolution of these fundamental rotor problems opened the way to progress, confidence built up rapidly, and, after several impressive cross-country flights, a C.8L was entered for the 1928 King Cup air race, and although it was forced to retire, it subsequently completed a 3,000-mile/4,800km tour of the British Isles. Later that year it flew from London to Paris, extending the tour to include Berlin, Brussels and Amsterdam, thus becoming the first rotating wing aircraft to cross the English Channel.

A predominant problem with the gyroplane was concerned with achieving initial rotor rotation. Several methods were attempted, in addition to the rope and drum system, which could take the rotor speed to 50 per cent of that required, at which point movement along the ground to reach flying speed was necessary, while tilting the rotor to establish autorotation.

Cierva’s autogiros were the wonder of the 1930s. In solving the problems of rotor dynamics and control, Cierva paved the way to a practical helicopter.

Another approach was to tilt the tail stabiliser to deflect engine slipstream up through the rotor. The most acceptable solution was finally achieved with the C.19, which was produced in some quantities, with a direct drive from the engine to the rotor fitted, through which the rotor could be accelerated up to speed. The system was then declutched for the commencement of a very short take-off run.

As Cierva’s autogiros achieved success and acceptance others began to follow, and with them came further innovation. Most important was the development of direct rotor control, which was achieved initially by tilting the rotor hub, and subsequently by the application of cyclic pitch, causing the blades to rise or fall at appropriate points in their rotation, thereby effectively tilting the rotor in the required direction.

The introduction of jump take-off was another major improvement in capability. The rotor was accelerated in fine pitch until the rotor speed required for flight was achieved. It was then declutched. The loss of torque caused the blades to swing forward on angled drag hinges, with a resultant increase in collective pitch causing the aircraft to leap into the air. With all the engine power applied to the forward-thrusting propeller, it was now possible to continue in forward flight with the rotor in autorotation.