Airco DH.10

The Airco DH.10 Amiens was a British twin-engined medium bomber designed and built towards the end of the First World War. It served briefly with the RAF postwar.

Design and development
The DH.10 was designed by Geoffrey de Havilland to meet the requirements of Air Board Specification A.2.b for a single- or twin-engined day bomber.[1] It was a development of the earlier Airco DH.3 bomber, which had flown in 1916, but had been rejected by the War Office because of a belief that strategic bombing would be ineffective and that twin engines were impracticable.[2]

The first prototype flew on 4 March 1918, powered by two 230 hp (186 kW) Siddeley Puma engines mounted as pushers.[3] When evaluated by the RAF, the performance of this prototype was well below expectation, reaching only 90 mph (145 km/h) at 15,000 ft (4,572 m) with the required bomb load,[1] compared with the specified 110 miles per hour (180 km/h).[4] Owing to this poor performance, the DH.10 was redesigned with more powerful engines in a tractor installation.

The second prototype, known as the Amiens Mark II was powered by two 360 hp (268 kW) Rolls-Royce Eagle VIII engines and first flew in April 1918, showing greatly superior performance and proving to be faster than the DH.9A while carrying twice the bomb load.[3] While shortages of the Eagle meant that the Amiens Mark II could not be put into production, it proved the design for the definitive aircraft, the Amiens Mark III, which was powered by the more readily available 395 hp (295 kW) Liberty 12 from America, as was the DH.9A.[1] Following successful evaluation, large orders were placed, with a total of 1,291 ordered.[5]

Operational history
First deliveries of DH.10s were to No. 104 Squadron RAF in November 1918, flying a single bombing mission on 10 November 1918 before the Armistice ended the First World War.[5] Postwar, DH.10s equipped 120 Squadron, which used them to operate an air mail service to the British Army of Occupation on the Rhine.[6] Amiens were also used by 97 Squadron (later re-numbered as 60 Squadron) which deployed to India. It provided support to the Army on the North-West Frontier, being used for bombing operations in the Third Anglo-Afghan war.[5] DH.10s were also used by 216 Squadron in Egypt, where they provided an air mail service between Cairo and Bagdhad, starting on 23 June 1921.[3]

Manufacturers
Daimler were producing 80 a month by the end of 1918. They were part of the BSA group which purchased Airco after the war and began a charter and scheduled service known as Daimler Air Hire and Daimler Airway.

Apart from the Aircraft Manufacturing Companies order for 420 aircraft the following companies had sub-contracts to build the DH.10, although due to the end of the war not all were built:
 * The Birmingham Carriage Company - 100
 * Daimler Limited - 150
 * National Aircraft Factory No.2 (Heaton Chapel) - 200
 * The Siddeley-Deasy Car Company - 150
 * The Alliance Aero Company - 200
 * Mann, Egerton & Company - 75

Variants

 * Amiens I
 * Prototype powered by two pusher Puma engines.


 * Amiens II
 * Prototype powered by two tractor Rolls-Royce Eagle engines.


 * Amiens III
 * Main production variant, powered by Liberty 12 engines mounted midway between wings, 221 built.


 * Amiens IIIA
 * Modified Mark III with engines directly attached to lower wings, 32 built, also known as the DH.10A


 * Amiens IIIC
 * Version powered by Rolls-Royce Eagle engines in case of shortages of Liberty engines, 5 built, also known as the DH.10C.

Military operators

 * United Kingdom
 * Royal Air Force [7]


 * No. 24 Squadron RAF  - used a single DH.10 for communications duties in 1920.
 * No. 27 Squadron RAF  - operated two DH.10s for operations over the North-West Frontier in December 1922.
 * No. 51 Squadron RAF  - evaluated a single DH.10 as a home defence fighter in 1918.
 * No. 60 Squadron RAF  - April 1920 to April 1923.
 * No. 97 Squadron RAF  - March 1919 to April 1920.
 * No. 104 Squadron RAF  - November 1918 to June 1919.
 * No. 120 Squadron RAF  - used a single DH.10 for night air mail trials in May 1919.
 * No. 216 Squadron RAF  - August 1920 to June 1922.

Civil operators

 * United Kingdom
 * Aircraft Transport and Travel Ltd operated the only DH.10 placed on the British Civil Register. This aircraft, G-EAJO, was used for regular airmail flights betweenHendon and Renfrew during the railway strike in October 1919. It was destroyed in a crash in April 1920.[8]
 * United States
 * At least one DH.10 was used for US Post Office air mail services on the New York - Cleveland - Omaha route in 1920.[9]

Specifications (Amiens IIIA)
Data from The British Bomber since 1914[5]

General characteristics Performance
 * Crew: Three
 * Length: 39 ft 7⅓ in (12.08 m)
 * Wingspan: 65 ft 6 in (19.97 m)
 * Height: 14 ft 6 in (4.42 m)
 * Wing area: 837 ft² (77.8 m²)
 * Empty weight: 5,750 lb (2,614 kg)
 * Loaded weight: 8,500 lb [10] (3,863 kg)
 * Max. takeoff weight: 9,060 lb (4,118 kg)
 * Powerplant: 2 × Liberty 12A  V-12 piston, 400 hp (298 kW) each
 * Maximum speed: 114 kn (131 mph, 211 km/h) at sea level
 * Service ceiling: 19,000 ft (5,800 m)
 * Wing loading: 10.2 lb/ft² (49.7 kg/m²)
 * Power/mass: 0.094 hp/lb (0.15 kW/kg)

Armament
 * Climb to 10,000 ft: 11 min
 * Endurance: 6 hours
 * 1 or 2 × .303 in  (7.7 mm) Lewis guns  on Scarff rings  at both nose and midships gunners cockpits
 * Up to 920 lb (417 kg) bombs carried internally