Beautifully engraved Certificate from the Helicopteracion Pescara issued in 1919. This historic document has an ornate border around it with images of helicopters, birds, and an winged man. In Barcelona, at the end of the first world war, an Argentinian engineer, Marquis PESCARA, developed a helicopter with two coaxial rotors rotating in opposite direction; each rotor was formed by four biplane rotary wings. PESCARA had invented the incidence cyclic variation achieved by twisting the blade. The pilot disposed of a cyclic variation stick and of a collective pitch lever. At the top of the cyclic variation pitch was a horizontal flywheel, which controlled the yaw by differential variation of the two wings collective pitch The first aircraft was equipped with a 45 HP engine insufficient to lift the 700 to 800 kg aircraft. It was merely used to establish lift measurements given by the rotors, and controls' actuation. These tests took place at the end of 1920. Marquis Pescara de Pateras is one the pioneers in the history of helicotper. This engineer created in 1919 his own Company in Spain, he built a first aeroplane equiped with a "Rhône" engine of 170 CV (HP), which was able to rise of one meter over the ground, but it was too heavy and crashed when it landed. In 1922, he established in France, improved his prototype and equiped it with a Hispano-Suiza engine of 180 CV(HP). This model only stayed 6 mm in the air during a competition in 1923. A 3rd model was able to fly 10 mn in 1924. He went back to Spain in 1925 and worked in the automobile industry. In Barcelona, at the end of the first world war, an Argentinian engineer, Marquis PESCARA, developed a helicopter with two coaxial rotors rotating in opposite direction; each rotor was formed by four biplane rotary wings. PESCARA had invented the incidence cyclic variation achieved by twisting the blade. The pilot disposed of a cyclic variation stick and of a collective pitch lever. At the top of the cyclic variation pitch was a horizontal flywheel, which controlled the yaw by differential variation of the two wings collective pitch The first aircraft was equipped with a 45 HP engine insufficient to lift the 700 to 800 kg aircraft. It was merely used to establish lift measurements given by the rotors, and controls' actuation. These tests took place at the end of 1920. The certificate was designed by Benjamin Rabier (1869-1939) famous humoristic animal illustrator, who was a good friend of Pescara. The development of the helicopter, perhaps one of man's most complex flying machines, has been, to say the least, somewhat protracted. The elementary growth of this remarkable aircraft is quite difficult to establish, and as a result it is difficult to pin the history of the helicopter to a single date and event. Unlike the fixed-wing flight historical `Mecca' of the Wright Brother's flight in 1903, rotary wing aviation has no single event. In its place the helicopter has a trail of advances that produced several key developments within in a short period. The following passage illustrates just some of rotary wing aviation's origins. The basic principles of helicopter flight have been in existence since almost the beginning of time. A brief glance at the fall of a sycamore seed case reveals the roots of rotary wing aviation. Accordingly, with such a timeless basis, the word helicopter comes to us from ancient sources: The helicopter's name deriving from the Greek words helix, meaning spiral, and pterion, meaning wing. John Fay suggests in The Helicopter that the Chinese were among the first to develop the idea of rotary-wing flight in the fourth Century AD. He quotes from "Pao Phu Tau": Someone asked the master about the principles (tao) of mounting to dangerous heights and travelling into the vast inane. The Master said, "Some have made flying cars (fei chhe) with wood from the inner part of the jujube tree, using ox-leather (straps) fastened to returning blades so as to set the machine in motion (huan chien i yin chhi chi)."[sic] (2) Fay goes on to quote Joseph Needham, author of Science and Civilisation in China, who suggests that although this is no more than a design for a toy, it is indeed the first recorded pattern of what we might understand as a helicopter. This toy is therefore one of the first tangible ancestors of the modern helicopter, even though it bears little resemblance to the aircraft of today. Designers since that time have sought throughout the centuries to produce rotary lift, perhaps for its ultimate convenience of being able to take off and land almost anywhere, much as did the birds that designers sought to emulate. The first recorded and most noted of designers that became interested in the idea was Leonardo Da Vinci in the Fifteenth Century, whose much-vaunted "spiral" design in 1490, (3) or "around 1483" according to a vague account in Milne's Flashing Blades, (4) has often been cited as the first serious attempt to produce a working helicopter. This too was only a design study, however, and was never put into practical use. The truly incredible Da Vinci was in this instance no more than an experimental engineer, putting onto paper age-old principles. (5) Between what is now easily recognisable as a helicopter and the Fourth Century alchemist Ko Hung's `spinning top' toy, there lies a wide plethora of minor inventions and advancements that have each no doubt added a small amount to the ultimate development of the aircraft. While much of the significant work was undertaken on the European Continent, the British aeronautical engineer Sir George Cayley produced a converti-plane in 1843, having built many `helicopter-like' aircraft beforehand (6) , while a man called Bourne flew a "model of Cayley's Chinese top powered by watch springs" that same year. (7) The ideas were most definitely simmering, but all lacked a suitable power source to achieve flight; primitive combustion engines lacked output and were both bulky and heavy. A more comprehensive list of the helicopter's slow, even incremental, development process is provided in John Fay's history section of The Helicopter, (Pp.125-145), while Everett-Heath's British Military Helicopters has an extensive section on the British developments of the aircraft. (8) For practical purposes, however, the real history of the helicopter began with the first rotary-wing aircraft to lift a man from the ground. At Douai in France, on either August 24th, 1907, or September 29th according to Fay (9) and Wragg (10) - it is unclear as to which is the case - brothers Louis and Jacques Breguet rose some two inches off the ground. (11) Fay also claimed that another Frenchman, Paul Cornu, achieved the "first free flight in his helicopter," (12) reporting an altitude reached of about six feet and endurance of only a few seconds at a time. This is also mentioned in Military Helicopters by Harrison and his associates, although they suggest it was only a twenty second flight to an altitude of thirty centimetres. (13) The truth has unfortunately been almost irrevocably lost along the way and it is propitious that the precise details are not especially relevant. Whatever the reality, however, British engineers were not far behind and in 1909 an aircraft made a tethered flight at the William Denny Brothers shipyard in Scotland, followed by a short free flight in 1914. (14) The first recorded example of serious military interest in rotary-wing projects was during the First World War, when the Germans Von Karman and Petrosczy, together with the Hungarian Asboth, "produced a lifting device intended to replace kite balloons for observation. It consisted of two superimposed lifting propellers." (15) (Although Prouty, in his introduction to Military Helicopter Design Technology, claims it was three Hungarians who produced the PKZ-2, making some thirty test flights before "accident and the Armistice ended the project." (16) ) The difficulties encountered with secondary sources are only too apparent here. After all the various minor improvements that had been made to the basic concept over the years, it was not until the late inter-War period that major advances began to be made. The quality and quantity of production materials available increased, coinciding with most important of all, great improvements in the field of engine technology. A small amount of experimentation was undertaken in Britain between the Wars, mainly in the field of the autogyro under the influence of the ex-patriate Spaniard Juan de la Cierva, until his accidental death in 1936. (17) Despite the use of two Cierva C.40 autogiros (the patented name for Cierva's autogyros) for Air Observation Post (artillery spotting) work with the British Expeditionary Force in France in the summer of 1940, (18) subsequent radar calibration work around the British coast throughout the War, (19) and the evident interest of the famous writer HG Wells after a visit to the United States in 1941, (20) this type of rotary wing flight was never to find widespread favour. The idea of the autogyro did not catch on, due to the better qualities of the helicopter; the autogyro could neither hover nor ascend vertically as it relied on forward motion to produce lift. The helicopter's superiority was made readily apparent by the planned replacement of the RAF's No.529(Rota) Squadron's autogiros with the Sikorsky R.6 aircraft in 1944. (21) The failure of the autogyro to become as ubiquitous as the helicopter was due almost entirely to one man's success in the field of rotary wing aviation. In the West, developments were led by a man whose name has became almost synonymous with the helicopter. A Russian who had fled from the Bolshevik revolution in 1917 to France, Igor Sikorsky had first been employed by the French Government to build a large fixed-wing bomber for the Allies, until the project was deemed obsolete by the peace. He then moved to the United States in 1919, (22) where after years of private development his work helped encourage the US Congress to agree a considerable budget of $2 million for rotary-wing research in 1938. (23) The US Army was, however, reluctant to have a single option available, and thus backed a rival program to the Congress-sponsored XR-1. A joint Sikorsky-Vought effort was chosen to be funded, and the project began life as the VS-300. (24) This aircraft, later modified to become the VS-316, was designed and built to a US Army Air Force contract that designated the machine as the XR-4 (25) and forms the most tangible link between the somewhat whimsical early design concept and practical aircraft capable of military operation. This machine was quite different from other developments to that date, and was in some ways light years ahead of aircraft built only a few years before, with a fully-enclosed plexi-glass cockpit, a fabric-covered tubular steel airframe and dual controls. (26) Powered only by a single 165hp Warner R5003 piston-engine, the XR-4, later the R-4 in production, was the first of many machines to suffer from insufficient power. This XR-4 first flew untethered on January 14th 1942, making six test flights on the day, the longest being 7 minutes 20 seconds. (27) Later that year, the US Army held a demonstration and in the process began Britain's involvement with the modern military helicopter. In the crowd at that demonstration were Wing Commander Brie, RAF and Commander Miller of the Royal Navy who, as part of the British Aircraft Delegation in Washington DC, were somewhat ironically trying to sell British-backed Cierva autogiros to the US Navy for anti-submarine operations. (28) Both English officers became convinced of the helicopter's future. The British delegation was not alone in being impressed with the demonstration, and the US Army took formal delivery of the prototype on 18th May that same year for further testing at Wright Field near Dayton, Ohio, some 761 miles from Sikorsky's Bridgeport plant in Connecticut. Instead of dismantling the aircraft for road transportation, the decision was made to fly the distance, carefully skirting the intervening Appalachian Mountains. The un-named aircrew left Bridgeport on May 13th, 1942 and, followed by a car-load of engineers, took five days, with a total flight time of just over sixteen hours and an average cruising speed of sixty miles an hour, to complete the journey. (29) "It is said that during this five day delivery flight, the helicopter emerged from being an experimental development, to become a fully-fledged aircraft." (30) This somewhat heady quote from Carey seems to perfectly summarise this first, and historic, practical flight. From this point onwards, the evolution of the helicopter simply accelerated in the United States.