Caudron G.4
The Caudron G.4 was a French biplane with twin engines, widely used during World War I as a bomber. It was designed by René and Gaston Caudron as an improvement over their single-engined Caudron G.3. The aircraft employed wing warping for banking. The first G.4 was built in 1915, and it was manufactured in France, England and Italy. It was the world's first twin-engine aircraft to be widely used, starting in March 1915. The Caudron G.4 was used as a reconnaissance bomber against the German Empire. Later, when Germany developed a fighter force, the aircraft  was used for night bombing. The G.4 was in use in Belgium, France, Finland, Italy, Portugal, the United Kingdom, and the United States. Development. While the Caudron G.3 was a reliable reconnaissance aircraft, it could not carry a useful bombload, and owing to its design, was difficult to fit with useful defensive armament. In order to solve these problems, the Caudron G4 was designed as a twin-engined development of the G.3, first flying in March 1915. While the G.4 had a similar pod and boom layout to the G.3, it had two Le Rhône rotary or Anzani 10 radial  engines mounted on struts between the wings instead of a single similar engine at the front of the crew nacelle, while wingspan was increased and the tailplane had four rudders instead of two. This allowed an observer/gunner position to be fitted in the nose of the nacelle, while the additional power allowed it to carry a bombload of 100 kg. The G.4 was one of the few twin-engine aircraft to be able to fly with one engine stopped. With two engines and a large wing area, the G.4 had enough power to break altitude records. In May 1915 , the French aviator Etienne Poulet broke the altitude record with 3 passengers, reaching a height of 5.850 m (19.226 ft). In Italy, on the 9th November 1916, the Italian aviator Guido Guidi set a world absolute altitude record, reaching a height of 26.083 ft (7.950m). A total of 1358 G.4s were produced in France, while a further 51 examples were produced by the A.E.R. company in Italy and 12 were built in Britain by the British Caudron company. Operational history. World War I. The G.4 entered service with the French Aéronautique Militaire in November 1915. It was the first  twin-engine aircraft in service in any numbers with the French. The Caudron G.4 was used to carry out bombing raids deep behind the front line, being used to attack targets as far away as the Rhineland. Increasing losses led to its withdrawal from day bombing missions by the French in the autumn of 1916. The British Royal Naval Air Service (RNAS) also used the G.4 as a bomber, receiving 55, of which twelve were licence-built by the British Caudron company and the remainder supplied from France. Number 4 and 5 Wing RNAS used the G.4 for attacks against  German seaplane and airship bases in Belgium. It was finally replaced in RNAS service by Handley Page O/100 aircraft in the autumn of 1917. Italian G.4s proved successful in operating in the mountainous Alpine fronts, where its good altitude capabilities proved useful. The G.4 was also used by the Imperial Russian Air Force for reconnaissance purposes. Use in Finland. The Finnish Air Force purchased one G.4 as well as two G.3s aircraft with spares, from Flyg Aktiebolaget on 26 April 1923 for 100,000 Finnish markka. The G.4 was used by the FAF as an ambulance aircraft in 1923. Variants. The  first G.4 prototype flew in March 1915. The G.4 was manufactured in three main versions, A.2 for reconnaissance, B.2 for bombing and E.2 for training. The A.2 was equipped with a radio for fire spotting, B.2 could carry of bombs and the E.2 was equipped with dual controls. G.4IB (French: "Blindage") was an armored version. There were also other bomber and escort aircraft versions. The Japanese Army received an unknown number of Caudron G.4s, which it designated 戊 1 (Bo 1). The Caudron G.6 was a further developed G.4, with a conventional fuselage and tail replacing the pod and boom  arrangement of the G.3. Survivors. Two Caudron G.4s are displayed in national museums. C.4263 is preserved at the Steven F. Udvar-Hazy Center in Virginia, US. C.1720 is displayed at the "Musée de l'Air et de l'Espace", Paris. A third Caudron G.4 is known to be under restoration in France in a private collection.