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From: Miloch <Miloch_member@newsguy.com>
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Subject: Airco De Havilland DH-4
Date: 22 Nov 2016 16:29:22 -0800
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https://en.wikipedia.org/wiki/Airco_DH.4
The Airco DH.4 was a British two-seat biplane day bomber of World War I. It was
designed by Geoffrey de Havilland (hence "DH") for Airco, and was the first
British two-seat light day-bomber to have an effective defensive armament. It
first flew in August 1916 and entered service with the Royal Flying Corps (RFC)
in March 1917. The majority of DH.4s were actually built as general purpose
two-seaters in the United States, for service with the American forces in
France.
The DH.4 was tried with several engines, of which the best was the 375 hp (280
kW) Rolls-Royce Eagle engine. Armament and ordnance for the aircraft consisted
of one 0.303 in (7.7 mm) Vickers machine gun for the pilot and one 0.303 in (7.7
mm) Lewis gun on a Scarff ring mounting for the observer. Two 230 lb (100 kg)
bombs or four 112 lb (51 kg) bombs could be carried. The DH.4 entered service on
6 March 1917 with No. 55 Squadron in France.
The DH.4 was designed by Geoffrey de Havilland as a light two-seat day bomber
powered by the new Beardmore Halford Pullinger (BHP) engine. The prototype first
flew in August 1916, powered by a prototype BHP engine rated at 230 hp (170 kW).
While the DH.4 trials were promising, the BHP engine required major redesign
before entering production, and the Rolls-Royce Eagle engine was selected as the
DH.4's powerplant. The first order for 50 DH.4s, powered by 250 hp (186 kW)
Eagle III engines was placed at the end of 1916.[3]
The aircraft was a conventional tractor two bay biplane of all-wooden
construction. The crew of two were accommodated in widely spaced cockpits,
separated by the fuel tank. It was armed with a single forward-firing
synchronised Vickers machine gun and one or two .303 in (7.7 mm) Lewis guns
fitted on a Scarff ring fired by the observer. A bomb load of 460 lb (210 kg)
could be fitted to external racks. While the crew arrangement gave good fields
of view for the pilot and observer, it caused communication problems between the
two crew members, particularly in combat, where the speaking tube linking the
cockpits was of limited use.
Role
Light bomber / General purpose
Manufacturer
Airco
First flight
August 1916
Introduction
March 1917
Retired
1932 (United States Army)
Primary users
United Kingdom
United States
Number built
6295, of which 4846 were built in the United States.
Unit cost
$11,250
Variants
DH9, DH9A, Dayton-Wright Cabin Cruiser
The DH.4 entered service with the RFC in January 1917, first being used by No.
55 Squadron. More squadrons were equipped with the type to increase the bombing
capacity of the RFC, with two squadrons re-equipping in May, and a total of six
squadrons by the end of the year.
The DH.4 proved a huge success and was often considered the best single-engined
bomber of World War I. Even when fully loaded with bombs, with its reliability
and impressive performance, the type proved highly popular with its crews. The
Airco DH.4 was easy to fly, and especially when fitted with the Rolls-Royce
Eagle engine, its speed and altitude performance gave it a good deal of
invulnerability to German fighter interception, so that the DH.4 often did not
require a fighter escort on missions, a concept furthered by de Havilland in the
later Mosquito in World War II.
A drawback of the design was the distance between pilot and observer, as they
were separated by the large main fuel tank. This made communication between the
crew members difficult, especially in combat with enemy fighters. There was also
some controversy (especially in American service) that this placement of the
fuel tank was inherently unsafe.
Specifications (DH.4 - Eagle VIII engine)
General characteristics
Crew: two
Length: 30 ft 8 in (9.35 m)
Wingspan: 43 feet 4 in (13.21 m)
Height: 11 ft (3.35 m)
Empty weight: 2,387 lb (1,085 kg)
Loaded weight: 3,472 lb (1,578 kg)
kW)
Performance
Maximum speed: 143 mph (230 km/h) at sea level
Range: 470 mi (770 km)
Service ceiling: 22,000 ft (6,700 m)
Rate of climb: 1,000 ft/min (305 m/min)
Power/mass: 0.108 hp/lb (0.266 kW/kg)
Climb to 10,000 ft: 9 min
Armament
Guns: Forward-firing .303 in (7.7 mm) Vickers machine gun, Lewis gun on Scarff
ring at rear
Bombs: 460 lb (210 kg) of bombs
*
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