Early practical flying machines

Early flying machines include all forms of aircraft studied or constructed before the development of the modern aeroplane. Once powered, controlled flight had been achieved, progress was still needed to create a practical flying machine for general use. This period leading up to World War I is sometimes called the pioneer era of aviation.

The Wright brothers
The Wrights solved both the control and power problems that confronted aeronautical pioneers. They invented roll control using wing warping and combined roll with simultaneous yaw control using a steerable rear rudder. Although wing-warping as a means of roll control was used only briefly during the early history of aviation, the innovation of combining roll and yaw control was a fundamental advance in flight control. For pitch control, the Wrights used a forward elevator (canard), another design element that later became outmoded.

The Wrights made rigorous wind-tunnel tests of airfoils and flight tests of full-size gliders. They not only built a working powered aircraft, the Wright Flyer, but also significantly advanced the science of aeronautical engineering.

They concentrated on the controllability of unpowered aircraft before attempting to fly a powered design. From 1900 to 1902, they built and flew a series of three gliders. The first two were much less efficient than the Wrights expected, based on experiments and writings of their 19th-century predecessors. Their 1900 glider had only about half the lift they anticipated, and the 1901 glider performed even more poorly, until makeshift modifications made it serviceable.

Seeking answers, the Wrights constructed their own wind tunnel and equipped it with a sophisticated measuring device to calculate lift and drag of 200 different model-size wing designs they created. As a result, the Wrights corrected earlier mistakes in calculations of lift and drag and used this knowledge to construct their 1902 glider, third in the series. It became the first manned, heavier-than-air flying machine that was mechanically controllable in all three axes: pitch, roll and yaw. Its pioneering design also included wings with a higher aspect ratio than the previous gliders. The brothers successfully flew the 1902 glider hundreds of times, and it performed far better than their earlier two versions.

To obtain adequate power for their engine-driven Flyer, the Wrights designed and built a low-powered internal combustion engine. Using their wind tunnel data, they designed and carved wooden propellers that were more efficient than any before, enabling them to gain adequate performance from their low engine power. The Flyer’s design was also influenced by the desire of the Wrights to teach themselves to fly safely without unreasonable risk to life and limb, and to make crashes survivable. The limited engine power resulted in low flying speeds and the need to take off into a headwind.

According to the Smithsonian Institution and Fédération Aéronautique Internationale (FAI), the Wrights made the first sustained, controlled, powered heavier-than-air manned flight at Kill Devil Hills, North Carolina, 4 miles (6.4 km) south of Kitty Hawk, North Carolina on 17 December 1903. The first flight by Orville Wright, of 120 feet (37 m) in 12 seconds, was recorded in a famous photograph. In the fourth flight of the same day, Wilbur Wright flew 852 feet (260 m) in 59 seconds. Modern analysis by Professor Fred E. C. Culick and Henry R. Rex (1985) has demonstrated that the 1903 Wright Flyer was so unstable as to be almost unmanageable by anyone but the Wrights, who had trained themselves in the 1902 glider.

The Wrights continued developing their flying machines and flying at Huffman Prairie near Dayton, Ohio in 1904–05. After a crash in 1905, they rebuilt the Flyer III and made important design changes. They almost doubled the size of the elevator and rudder and moved them about twice the distance from the wings. They added two fixed vertical vanes (called “blinkers”) between the elevators, and gave the wings a very slight dihedral. They disconnected the rudder from the wing-warping control, and as in all future aircraft, placed it on a separate control handle. The Flyer III became the first practical aircraft (though without wheels and using a launching device), flying consistently under full control and bringing its pilot back to the starting point safely and landing without damage. On 5 October 1905, Wilbur flew 24 miles (39 km) in 39 minutes 23 seconds”.

Eventually the Wrights would abandon the foreplane altogether, with the Model B of 1910 instead having a tail plane in the manner which was by then becoming conventional.

According to the April 1907 issue of the Scientific American magazine, the Wright brothers seemed to have the most advanced knowledge of heavier-than-air navigation at the time. However, the same magazine issue also claimed that no public flight had been made in the United States before its April 1907 issue. Hence, they devised the Scientific American Aeronautic Trophy in order to encourage the development of a heavier-than-air flying machine.

The first practical aircraft
Once powered, controlled flight had been achieved, progress was still needed to create a practical flying machine for general use. This period leading up to World War I is sometimes called the pioneer era of aviation.

Reliable power
The history of early powered flight is very much the history of early engine construction. The Wrights designed their own engines. They used a single flight engine, a 12 horsepower (8.9 kW) water-cooled four-cylinder inline type with five main bearings and fuel injection. Whitehead’s craft was powered by two engines of his design: a ground engine of 10 horsepower (7.5 kW) which drove the front wheels in an effort to reach takeoff speed and a 20 horsepower (15 kW) acetylene engine powering the propellers. Whitehead was an experienced machinist, and he is reported to have raised funds for his aircraft by making and selling engines to other aviators. Most early engines were neither powerful nor reliable enough for practical use, and the development of improved engines went hand-in-hand with improvements in the airframes themselves.

In Europe, Léon Levavasseur’s Antoinette 8V pioneering example of the V-8 engine format, first patented in 1902, dominated flight for several years after it was introduced in 1906, powering many notable craft of that era. Incorporating direct fuel injection, evaporative water cooling and other advanced features, it generated around 50 horsepower (37 kW).

The British Green C.4 of 1908 followed the Wright’s pattern of a four-cylinder inline water-cooled design but produced 52 horsepower (39 kW). It powered many successful pioneer aircraft including those of A.V. Roe.

Horizontally opposed designs were also produced. The four-cylinder water-cooled de Havilland Iris achieved 45 horsepower (34 kW) but was little used, while the successful two-cylinder Nieuport design achieved 28 hp (21 kW) in 1910.

1909 saw radial engine forms rise to significance. The Anzani 3-cylinder semi-radial or fan engine of 1909 (also built in a true, 120° cylinder angle radial form) developed only 25 horsepower (19 kW) but was much lighter than the Antoinette, and was chosen by Louis Blériot for his cross-Channel flight. More radical was the Seguin brothers’ series of Gnôme rotary radial engines, starring with the Gnome Omega 50 horsepower (37 kW) air-cooled seven-cylinder rotary engine in 1906. In a rotary engine, the crankshaft is fixed to the airframe and the whole engine casing and cylinders rotate with the propeller. Although this type had been introduced as long ago as 1887 by Lawrence Hargrave, improvements made to the Gnome created a robust, relatively reliable and lightweight design which revolutionised aviation and would see continuous development over the next ten years. Fuel was introduced into each cylinder direct from the crankcase meaning that only an exhaust valve was required. The larger and more powerful nine-cylinder, 80 horsepower Le Rhône 9C rotary was introduced in 1913 and was widely adopted for military use.

Inline and vee types remained popular, with the German company Mercedes producing a series of water-cooled six-cylinder models. In 1913, they introduced the highly successful 75 kilowatts (101 hp) D.I series.

Lift and efficiency
The lightness and strength of the biplane is offset by the inefficiency inherent in placing two wings so close together. Biplane and monoplane designs vied with each other, with both still in production by the outbreak of war in 1914.

A notable development, although a failure, was the first cantilever monoplane ever built. The Antoinette Monobloc of 1911 had a fully enclosed cockpit and faired undercarriage but its V-8 engine’s 50 horsepower (37 kW) output was not enough for it to fly for more than a few feet at most. More successful was the Deperdussin braced monoplane, which won the inaugural 1913 Schneider Trophy race flown by Maurice Prévost, completing 28 circuits of the 10 km (6.2 mi) course with an average speed of 73.63 kilometres per hour (45.75 mph).

Triplanes too were experimented with, notably a series built between 1909 and 1910 by the British pioneer A.V. Roe. Going one better with four wings the quadruplane too made rare appearances. The Multiplane, having large numbers of very thin wings, was also experimented with, most successfully by Horatio Phillips. His final prototype confirmed the inefficiency and poor performance of the idea.

Other radical approaches to wing design were also being tried. The Scottish-born inventor Alexander Graham Bell devised a cellular octahedral wing form which, like the multiplane, proved disappointingly inefficient. Other lacklustre performers included the Edwards Rhomboidal, the Lee-Richards annular wing and varying numbers of wings one after the other in tandem.

Many of these early experimental forms were in principle quite practical and have since reappeared.

Stability and control
Early work had focused primary on making a craft stable enough to fly but failed to offer full controllability, while the Wrights had sacrificed stability in order to make their Flyer fully controllable. A practical aircraft requires both. Although stability had been achieved by several designs, the principles were not fully understood and progress was erratic. The aileron slowly replaced wing warping for lateral control although designers sometimes, as with the Blériot XI, returned briefly to wing warping. Similarly, all-flying tail surfaces gave way to fixed stabilizers with hinged control surfaces attached. The canard pusher configuration of the early Wright Flyers was supplanted by tractor propeller aircraft designs.

In France, progress was relatively rapid.
In 1906, the Brazilian Alberto Santos-Dumont made public flights in France with his 14-bis. A canard pusher biplane with pronounced wing dihedral, it had a Hargrave-style box-cell wing with a forward-mounted “boxkite” assembly which was movable to act as both elevator and rudder. He later added auxiliary surfaces between the wings as primitive ailerons to provide lateral control. His flight was the first made by a powered heavier-than-air machine to be verified by the Aéro-Club de France, and won the Deutsch-Archdeacon Prize for the first officially observed flight of more than 25 metres (82 ft). It later set the first world record recognized by the Federation Aeronautique Internationale by flying 220 metres (720 ft) in 21.5 seconds.

The next year Louis Blériot flew the Blériot VII, a tractor monoplane with full three-axis control using the horizontal tail surfaces as combined elevators and ailerons. Its immediate descendant, the Blériot VIII, was the very first airframe to bring together the recognizable elements of the modern aircraft flight control system in April 1908. Where Horatio Phillips and Traian Vuia had failed, Blériot’s was the first practical tractor monoplane and marked the start of a trend in French aviation. By 1909, he had developed this configuration to the point where the Blériot XI was able to cross the English Channel, among other refinements using the tail surfaces only as elevators and using wing warping for lateral control. Another design that appeared in 1907 was the Voisin biplane. This lacked any provision for lateral control, and could only make shallow turns using only rudder control, but was flown with increasing success during the year by Henri Farman, and on 13 January 1908 he won the 50,000 francs Deutsch de la Meurthe-Archdeacon Grand Prix de l’Aviation for being the first aviator to complete an officially observed 1 kilometre closed circuit flight, including taking off and landing under the aircraft’s own power.

The designs of the French pioneer Léon Levavasseur are better known by the name of the Antoinette company which he founded. His Antoinette IV of 1908 was a monoplane of what is now the conventional configuration, with tailplane and fin each bearing movable control surfaces, and ailerons on the wings. The ailerons were not sufficiently effective and on later models were replaced by wing warping.

At the end of 1908, the Voisin brothers sold an aircraft ordered by Henri Farman to J. T. C. Moore-Brabazon. Angered, Farman built his own aircraft, adapting the Voisin design by adding ailerons. Following further modifications to the tail surfaces and ailerons, the Farman III became the most popular aeroplane sold between 1909 and 1911, and was widely imitated. In Britain the American expatriate Samuel Cody flew an aircraft similar in layout to the Wright flyer in 1908, incorporating a tailplane as well as a large front elevator. In 1910 an improved model fitted with between-wing ailerons won the Michelin Cup competition, while Geoffrey de Havilland’s second Farman-style aircraft had ailerons on the upper wing and became the Royal Aircraft Factory F.E.1. The Bristol Boxkite, a copy of the Farman III, was manufactured in quantity. In the USA Glenn Curtiss had flown first the AEA June Bug and then his Golden Flyer, which in 1910 achieved the first naval deck landing and takeoff. Meanwhile, the Wrights themselves had also been wrestling with the problem of achieving both stability and control, experimenting further with the foreplane before first adding a second small plane at the tail and then finally removing the foreplane altogether. They announced their two-seat Model B in 1910 and licensed it for production in 1911 as the Burgess Model F.

Many other more radical layouts were tried, with only a few showing any promise. In the United Kingdom, J. W. Dunne developed a series of tailless pusher designs having swept wings with a conical upper surface. His D.5 biplane flew in 1910 and proved fully stable. Dunne deliberately avoided full three-axis control, devising instead a system which was easier to operate and which he regarded as far safer in practice. Dunne’s system would not be widely adopted. His tailless design reached its peak with the D.8 which was manufactured under license in France by Nieuport and in the USA as the Burgess-Dunne, however it was rejected as a practical warplane by the British Army, in which Dunne was an officer, because it was too stable and hence not manoeuvrable enough in battle.

Seaplanes
1901 in Austria, Wilhelm Kress fails to take off in his underpowered Drachenflieger, a floatplane featuring twin pontoons made of aluminium and three wings in tandem.

1910 in France, Henri Fabre makes the first seaplane flight in his Hydravion. It was a monoplane with a biplane foreplane and three short floats in tricycle layout.

1912 The world’s first seaplane carrier, the French Navy’s Foudre, embarks her first floatplane, a Voisin Canard.

A problem with early seaplanes was the tendency for suction between the water and the aircraft as speed increased, holding the aircraft down and hindering takeoff. The British designer John Cyril Porte invented the technique of placing a step in the bottom of the aircraft to break the suction, and this was incorporated in the 1914 Curtiss Model H.

Military use
In 1909 aeroplanes remained frail and of little practical use. The limited engine power available meant that the effective payload was extremely limited. The basic structural and materials technology of the airframes mostly consisted of hardwood materials or steel tubing, braced with steel wires and covered in linen fabric doped with a flammable stiffener and sealant. The need to save weight meant that most aircraft were structurally fragile, and not infrequently broke up in flight especially when performing violent manoeuvres, such as pulling out of a steep dive, which would be required in combat.

However these evolving flying machines were recognised to be not just toys, but weapons in the making. In 1909 the Italian staff officer Giulio Douhet remarked:

The sky is about to become another battlefield no less important than the battlefields on land and sea….In order to conquer the air, it is necessary to deprive the enemy of all means of flying, by striking at him in the air, at his bases of operation, or at his production centers. We had better get accustomed to this idea, and prepare ourselves.

— Giulio Douhet (Italian staff officer), 1909
In 1911 Captain Bertram Dickson, the first British military officer to fly and the first British military officer to perform an aerial reconnaissance mission in a fixed-wing aircraft during army manoeuvres in 1910, predicted the military use of aircraft and the ensuing development and escalation of aerial combat in a submission to the UK Technical Sub-Committee for Imperial Defence.

Missiles were dropped from an aeroplane for the first time when United States Army Lieutenant Paul W. Beck dropped sandbags simulating bombs over Los Angeles, California.

Aeroplanes were first used in warfare during the Italo-Turkish War of 1911–1912. The first operational use took place on 23 October 1911, when Captain Carlo Piazza made a flight near Benghazi in a Blériot XI. The first aerial bombardment followed shortly afterwards on 1 November, when Second Lieutenant Giulio Gavotti dropped four bombs on two oases held by the Turks. The first photographic reconnaissance flight took place in March 1912, also flown by Captain Piazza.

Some types developed during this period would see military service into, or even throughout, World War I. These include the Etrich Taube of 1910, Fokker Spin of 1911, Royal Aircraft Factory BE.2, Sopwith Tabloid/Schneider and a variety of obsolescent types that would be used for pilot training. The Sikorsky Ilya Muromets was the first four-engined aircraft to ever enter production and the largest of its day, the prototype first flying in 1914 just before the outbreak of war. The type would go on to see service in both bomber and transport roles.

Helicopters
The early work on powered rotor lift was followed up by later investigators, independently from the development of fixed-wing aircraft.

In 19th century France an association was set up to collaborate on helicopter designs, of which there were many. In 1863 Gustave de Ponton d’Amécourt constructed a model using the established counter-rotating rotors. Initially powered by steam it failed, but a clockwork version did fly. Other designs, covering a wide variety of forms, included Pomés and De la Pauze (1871), Pénaud, Achenbach (1874), Dieuaide (1887), Melikoff (1877), Forlanini (1877), Castel (1878), and Dandrieux (1878–79). Of these, Forlanini’s steam-powered contra-rotating model flew for 20 seconds, reaching a height of 13 metres (43 ft), and Dandrieux’ rubber-powered model also flew.

Hiram Maxim’s father conceived of a helicopter powered by two counter-rotating rotors, but was unable to find a powerful enough engine to build it. Hiram himself sketched out plans for a helicopter in 1872 before turning his attention to fixed-wing flight.

In 1907, the French Breguet-Richet Gyroplane No. 1 lifted off in a “tethered” test flight, becoming the first manned helicopter to rise from the ground. It rose about 60 centimetres (24 in) and hovered for a minute. However, the flight proved to be extremely unsteady.

Two months later at Lisenux, France, Paul Cornu made the first free flight in a manned rotary-winged craft in his Cornu helicopter, lifting to 30 centimetres (12 in) and remaining aloft for 20 seconds.

Source from Wikipedia