The DH.6 was designed for an RFC’s urgent requirement for a trainer in autumn 1916, for ease of manufacture, maintenance and repair. Instead of two cockpits, there was one communal cockpit which made it easier for the tutor to instruct his pupil. The dual controls could be disengaged by the instructor in the case of an emergency, by means of a handle alongside the cockpit position. The aircraft had a two-bay wing that had been designed for low speed and good handling, a robust fin and horn-balanced rudder and was powered by a 90 hp RAF.1a engine.

Airco DH 6 Article

Two prototypes, A5175 and A5176, were built, each with a communal tandem seat cockpit, and powered by a 90 hp RAF la air-cooled V engine. The four rectangular wing panels were interchangeable, as were the tailplane halves.

The prototype was built in October 1916, and after flight trials was immediately accepted by the War Office. An initial 200 were ordered in January 1917. But these were to be built by the Graham-White Aviation Company because the Airco Company was already heavily committed to the production of the DH.4 and DH.5. Then in April a further 500 were ordered, so other manufacturers had to be brought in to assist. Among these were: the Gloucestershire Aircraft Company, Kingsbury Aviation Co. Hraland & Wolff and Canadian Aeroplanes. This was the first British-designed aircraft to be built in Canada.

Production of 2950 by several British companies (900 of them by Airco) began in January 1917. Most of these retained the RAF (Royal Aircraft Factory) powerplant, but some utilized a cowled 90 hp Curtiss OX¬5 or an 80 hp Renault.

DH6s began to be phased out of the RFC in late 1917 with the arrival of the Avro 504 as the standard British trainer, but about 200 were put into service in early 1918 with 34 flights of the RNAS (five operated by the US Navy) on antisubmarine coastal patrol. Flown as single seaters, they could carry a 45.5 kg (100 lb) bombload.
About 70 D.H.6s were sent to RFC Home Defence units in 1918.

The RAF possessed 1050 of the type in October 1918, and more than 50 were put on to the civil register after the Armistice.

Gallery

Variation:
Blackburn Alula D.H.6

Engine: 90 hp RAF la
Wingspan: 10.95 m / 35 ft 11 in
Length: 8.32 m / 27 ft 3.5 in
Height: 3.2 m / 10 ft 9.5 in
Empty weight: 662 kg / 1460 lb
Gross weight: 919 kg / 2026 lb
Maximum speed: 106 km/h / 66 mph
Endurance: 2 hr 30 min
Armament: 1 x .303 Vickers mg (rear cockpit)

The realisation that the German aircraft performance was substantially better than the Allied models forced Geoffery de Havilland to like at an idea put forward by Constantine Constantinesco, who claimed to have perfected an interruptor mechanism. The mechanism worked, and de Havilland got to work designing a single-bay biplane with a tractor engine upon which the mechanism could be fitted.

Airco DH 5 Article

In an effort to enhance the performance of the aircraft and increase the pilot’s all-round view, de Havilland designed a 27in backward stagger on the upper wing, which brought the cockpit in front of the upper wing’s leading edge. Although under normal test conditions this was acceptable, under combat conditions the pilot had no view above or behind and this was one of the reasons why the aircraft was later relegated to low-level duties. Designed in 1916, the Airco D.H.5 was intended to replace the single seat DH2.

The wooden box-girder fuselage, roundd on top with flat sides, was strengthened with plywood. With conventional construction of wood and fabric, landing gear of fixed tailskid type, and powered by an 82-kW (110-hp) Le Rhóne 9J rotary engine, the initially unarmed prototype, A5172, was built in late 1916. It was sent to France for service trials in December 1916, armed with a forward firing Vickers gun fixed to move upwards through a 60 degree arc.

The prototype was flown by Major Mills first to No.1 Aircraft Depot, and then to No.2 Aircraft Depot before going to the No.24 Squadron, RFC, where flight evaluation was carried out.

Initial tests discovered that the DH.5s fitted with the 110 hp Le Rhone engine vibrated so badly that the pilot was unable to read his instruments. At first the blame was laid squarely on the engine, but after other engines had been tried, it was discovered that it was the engine bearer plate that was the problem. Strengthening the plate solved the problem.

After satisfactory performance, the D.H.5 was ordered into production and 549 were built by Airco; the Dar-racq Motor Engineering company; March, Jones & Cribb; and the British Caudron company. These differed from the prototype in having the fixed 0.303 in (7.7 mm) Vickers gun fitted with Constantinesco interrupter gear. The single Vickea machine gun was mounted on top of the front section and offset to the portside f the fuselage, and synchronised to fire through the propeller. It was powered by a 110 hp Le Rhone rotary engine, giving it a top speed of 109 mph.

Other problems appeared with the Constantinesco interrupter gear. Both No.24 and No.25 Squadron were out of action. Other squadrons that had the DH.5 on their strength also suffered from this problem, rendering their aircraft non-operational.

Over 550 of the aircraft were built: 200 by Airco, and 350 by three sub-contractors: the Darracq Motor Engineering Co Ltd of London; Messers March, Jones & Cribb of Leeds and the British Caudron Co Ltd, London.

Deliveries to Nos 24 and 32 Squadrons in France began in May 1917.
Easily outflown by contemporary fighters at altitudes above 3050m and after suffering fairly heavy losses in November 1917, the D.H.5 was used for ground-attack sorties with four 11 kg (25 lb) Cooper bombs. D.H.5s were put to such use in the battle of Cambrai in autumn 1917. By this time S.E.5as had begun to replace D.H.5s and their first line service life of eight months had ended by January 1918, after which they were used for training in Britain.

The DH.5 was the original equipment of the Australian 2 AFC which proved too slow for effective air fighting, but acquitted itself quite well as a ground-attack aircraft during the Battle of Cambrai.

One D.H.5 was experimentally fitted with a 45 degrees upward angled Vickers, though no D.H.5s were used for Home Defence.

Production of D.H.5s totalled about 550, built by Airco (200), and sub-contracted to the British Caudron Company (50), The Darracq Motor Engineering Company (200), and March, Jones and Cribb (about 100). For experimental purposes a single example was powered by an 82-kW (110-hp) Clerget rotary engine.

Gallery

DH 5
Engine: Le Rhone 9J, 110 hp or Clerget 9Z, 100 hp, or Gnome Monosoupape, 100 hp
Wingspan: 25 ft 8 in / 7.8 m
Length: 22 ft 0 in / 6.7 m
Height: 9 ft 1.5 in / 2.7 m
Empty weight: 1010 lb / 458 kg
Loaded weight: 1492 lb / 676 kg
Max speed: 102 mph / 164 kph
Ceiling: 16,000 ft / 4876 m
Endurance: 2 hr 3 min
Armament: 1 x .303 Vickers mg
Bombload: 4 x 250 lb

Airco DH.5
Engine: one 82-kW (110-hp) Le Rhóne rotary piston
Wingspan: 7.82 m / 25 ft 8 in
Length: 6.71 m / 22 ft 0 in
Height: 2.78 m / 9 ft 1 in
Wing area: 19.70 sq.m / 212.05 sq ft
Max take-off weight: 677 kg / 1493 lb
Empty weight: 458 kg / 1010 lb
Fuel capacity: 26 Imp.Gal.
Maximum level speed at 3050m (10,000 ft): 164 km/h / 102 mph / 89kt
Climb to 1980m (6,500ft): 6 minutes 55 seconds
Service ceiling: 4875m / 16,000ft
Endurance: 2 hours 45 minutes
Armament: one fixed forward-firing 7.7-mm (0.303-in) Vickers machine gun
Bombload: four 11.3-kg (25-lb) bombs on underwing racks
Accommodation: 1

The two seat D.H.4 was designed as a fast day bomber, with a conventional two-bay biplane fuselage of wood and fabric structure.

The fuselage was constructed from spruce and ash with its forward fuselage having a plywood covering. There were two cockpits; the rear observer’s cockpit had a scarff ring fitted, on which was mounted either a single or twin Lewis machine guns. In front of the pilot was mounted a single, synchronised forward-firing Vickers machine gun.. Two 230 lb bombs or four 112 lb bombs were mounted in racks under both the fuselage and wings. The fin and rudder were the standard shape, and the undercarriage consisted of two 6 ft 9 in (2.0 m) rubber cords wound into nine turns for each of the wheels. The braced tail unit had an adjustable tailplane, to enable the pilot to trim the aircraft in flight, and landing gear was of fixed tailwheel type.

During the period when design of the D.H.4 was being finalised, a new engine was designed and constructed. Designated B.H.P. and rated at 172kW (230 hp), the prototype engine was installed in the prototype D.H.4, and early flight testing began in August 1916. Fifty were ordered in the summer of 1916, before the prototype had flown.

Airco DH 4 Article

In August 1916 the DH.4 first flew, piloted by Geoffery de Havilland.

A 230 hp B.H.P. 6-cylinder, water cooled engine powered the prototype, producing a speed of 106 mph. The aircraft was sent to the Central Flying School Testing Flght for evaluation, and the report that came back was nothing less than ‘highly commended’.

Considerable delays occurred in getting the B.H.P. into production but an alternative powerplant, rated at 186 kW (250 hp), became available from Rolls-Royce. This engine was to become known as the Eagle In the meantime, de Havilland was building the second prototype with a number of modifications. The B.H.P. engine had been larger than anticipated and had extended and raised the nose or the aircraft, reducing the pilot’s forward visibility. By installing the new 250 hp Rolls-Royce engine, the nose was lowered by 3in which improved visibility considerably.

Captain R.H.Mayo, who had demonstrated the aircraft to a number of squadron commanders who also flew the aircraft, had flown the prototype to France. An immediate order for 50 of the aircraft was made, followed three months later by a second order for a further 690 of the aircraft. The production lines at Airco went into top gear immediately. The 250 hp Rolls Royce IIIs or IVs (later known as Eagles) were fitted to production aircraft.

Production aircraft included improvements introduced by the second prototype, including a ring mounting for the observer’s Lewis gun in the rear cockpit; a forward firing Vickers gun, with a Constantinesco synchronizing gear, was fitted in front for the pilot. Some RNAS D.H.4s had twin Vickers and an elevated Scariff ring for the Lewis. The maximum bombload was two 104 kg (230 lb), four 51 kg (112 lb) or an equivalent weight of smaller bombs.

The first production DH.4s were delivered to No.55 Squadron, RFC on 6 March 1917 and had their first operational flight one month later at Valenciennes. They were used on a number of bombing missions and high-altitude photo-reconnaissance flights. There were several problems that caused some concerns among the crews that flew them. Communication between the two cockpits was impossible with the wind, engine noise and heat of battle, the Gosport Tube was useless. The 60 gallon fuel tank mounted between the cockpits would expode if hit.

The RNAS took a strong interest in the DH.4 after it had been lent one fitted with the 375 hp Eagle VIII, and subsequently ordered fifty of the aircraft. The one aircraft they had been lent was assigned to No.2 Squadron, RNAS in Dunkerque, where it operated until the end of the war. When the 280-kW (375-hp) Eagle VIII became available, D.H.4s with this engine were superior in performance to most of the contemporary fighter aircraft.

The D.H.4 was operating 11 squadrons of the RFC or RNAS and 13 American squadrons by the late spring of 1918. The type also served with the Royal Naval Air Service (combined with the RFC to form the RAF on 1 April 1918) for coastal patrol, and was used to equip home defence squadrons.

Improvements to engine manufacture were ongoing, and Rolls-Royce was no exception. Their only problem was that they could not keep up with demand, and their cause was not helped by the government’s intransigence in denying them permission to extend their factory and build a special repair shop. The development of the Eagle series of engines by Rolls-Royce produced the 375 hp Eagle VIII. This powerful engine drove a much larger propeller that required a taller under carriage and sturdier frame.

Two were fitted out experimentally with extra fuel tanks, enough to give 14 hours’ flying, and were intended to carry out a special photographic reconnaissance of shipping in the Kiel Canal. This mission never took place, but the two D.H.4s were later fitted instead with twin over wing Lewis guns and used for night fighting.

The DH4 was withdrawn from RAF service soon after the Armistice, and in the early postwar years many were supplied to the air forces of Belgium (where SABCA also built 15 in 1926), Canada, Chile, Greece, Persia, New Zealand, South Africa and Spain. Some remained in service until the early 1930s, and others were converted for civil use in the 1920s.

Production in Britain totalled 1450, built by by Airco and under sub-contract by F.W. Berwick and Company, Glendower Aircraft Company, Palladium Autocars Ltd, The Vulcan Motor and Engineering Company, Waring & Gillow Ltd, and the Westland Aircraft Works. At the end of the First World War 548 were still in service.

Almost all of the delays were the result of engine manufacturers not being able to deliver their engines on time, and when they did, Airco discovered that some of the engines had had modifications made which resulted in them having to alter the aircraft’s airframes to accommodate them. Even with all the delays, the government decided to supply the Russian Government with fifty DH.4s. These models were to be fitted with the Fiat A.12 engine. The Russian winter had set in and the Bolshevik revolution was about to break out, so it was impossible to deliver the aircraft. Immediately, the RFC used them to supplement their bomber force. The British government agreed with the Russians to replace the aircraft with an additional twenty-five in the spring of 1918, but because of the outcome of the revolution in Russia this never happened.

Rolls Royce engine production could not keep pace with this, resulting in several batches of D.H.4s being fitted with such alternative powerplants. Other than the Rolls-Royce III, IV or Eagle, these included the 149-kW (200-hp) R.A.F.3a, 172-kW (230-hp) Siddeley Puma, Adriatic (200 hp), and 194-kW (260-hp) Fiat A 12.

Experimental engine installations included a 224-kW (300-hp) Renault l2Fe, 239-kW (320-hp) Armstrong Siddeley Jaguar I, 263-kW (353-hp) Rolls-Royce ‘G’, 298-kW (400-hp; Sunbeam Matabele, and a Ricardo-Halford supercharged engine. lncreasing engine powers required larger diameter propellers, steadily reducing clearance between the propeller tip and the ground, and resulted in the main landing gear units being extended sufficiently to cater for future growth.

Highest performance was achieved with the Rolls Royce Eagle VIII (375 hp), which gave the D.H.4 a top speed of 230 km/h (143 mph).

Armament of the standard D.H.4s consisted of a fixed forward-firing Vickers machine-gun that was synchronised by a Constantinesco interrupter gear; the observer/gunner had one or two Lewis guns mounted on a Scarff ring. Underfuselage and underwing bomb racks had a maximum capacity of 209 kg (4601b). Aircraft built by Westland Aircraft for the RNAS had twin Vickers machine-guns for the pilot, and the rear Lewis guns were on a pillar mounting. Two examples of the D.H.4 were modified to mount a Coventry Ordnance works (C.O.W.) quick-firing gun, which fired a 0.68-kg (1.5-lb) shell. Mounted to fire almost vertically upward, this gun as intended for attacks on German Zeppelins; but by the time they were ready for service, Zeppelin raids on Britain had ended.

The United States possessed no combat-worthy aircraft upon entry into World War I in 1917 and selected the DH-4 because of its comparatively simple construction and it was well-suited to the 400-horsepower Liberty V-12 engine.

In the summer of 1917, a pattern aircraft had been fitted with a 400 hp Liberty 12 engine and the US government ordered more than 12,000 ‘Liberty Planes’, although 7502 were cancelled after the Armistice. A total of 4846 were completed by Dayton Wright (3106), Fisher Body Division of General Motors (1600) and Standard Aircraft Corporation (140) and the Atlantic Aircraft Corp, New Jersey, and Boeing Airplane Corp, Seattle, before production ceased at the war’s end in 1918.

By war’s end, 13 Army Air Service squadrons, five of them bomber squadrons, were equipped with them (from August 1918). In addition, four combined Navy-Marine squadrons of the US Naval Northern Bombing Group were flying DH-4s along the Belgian coast. Of the 4,346 DH-4s built in the United States, 1,213 were delivered to France, but of those only 696 reached the Zone of Advance. In the postwar period, the DH-4 was the principal aircraft used by the U.S. Government when airmail service began in 1918.

The Americans designated the initial version the DH4A, but it was obsolescent by the time it entered US service, having had to be reworked to suit it to US production techniques, and the improved DH 4B was ready too late (October 1918) to take its place on the Western Front. American built DH 4As were armed with two Marlin or Browning machine-guns in the front and two Lewis guns in the rear cockpit, and could carry up to 150 kg (332 lb) of bombs. After the war, 283 of the Army’s DH 4As were transferred to the US Navy or Marine Corps as observation or transport planes until 1932.

After the war a building and conversion programme (of more than 1500 DH4As) kept the DH4B, DH 4M (for Modernized) and other later variants in US service until 1932.

The DH4B rectified a fault of the original D.H.4 by relocating the main fuel tank (previously between the two cockpits) in front of the pilot’s cockpit. Boeing built 150 DH4Ms for the US Army and 30 O2B-1s for the Marines; Fokker Atlantic Aircraft built 135 DH 4Ms.

Aeromarine converted 125 DH-4B under contract for de Havilland, first flown in 1917.

One Aeromarine DH-4B conversion example was specially tested at Wright Field. Possibly same as Whitbeck Special.

The NASM collection has the prototype American-built DH-4, manufactured by the Dayton-Wright Airplane Company. This airplane was used in more than 2,600 experiments until its retirement in April 1919. It was also the airplane in which Orville Wright made his last flight as a pilot in 1918.

The career of the D.H.4 was to continue long After the Armistice of 1918, war surplus examples went to the Belgian, Greek, Japanese, and Spanish air forces, with American-built machines continuing to serve with the United States Army Air Corps and with many Latin American countries. In 1924 the Mexican government procured a number of US built D.H.4B bombers. Large numbers of variants appeared in the USA during the early post-war years, these being conversions of ex-military aircraft, and many pioneering flights were made with them. Two USAAC DH-4Bs were used in the first successfu experiments of inflight refuelling.

After Lts. Macready and Kelly set the record, the crew at San Diego’s Rockwell Field immediately set about creating a system to solve the problem. On June 27, 1923, Lts. Virgil Hine and Frank W. Seifert completed the first successful aircraft-to-aircraft in-flight refueling when they transferred gasoline via gravity feed through a fifty-foot hose connected to the bottom of their DH-4B that stretched to a DH-4B flown beneath them by Lts. Lowell H. Smith and John P. Richter.

Smith and Richter tried breaking Macready and Kelly’s record the very next day, but a gas valve malfunctioned, forcing Smith to land the plane prematurely. In August 1923, they flew 37 hours and 15 minutes on their way to setting 16 new world records for distance, speed, and duration. In October, they flew 1,250 miles nonstop from Canada’s border to Mexico’s, refueling midair three times and finally proving the system was a reliable option to extend an aircraft’s flight range.

The D.H.4 was not limited to military applications in these early years of peace, and in the UK it was the earliest type to be used as a civil transport by Holt Thomas’ Aircraft Transport & Travel Ltd for the first cross-Channel service between London and Paris. For peace celebrations in Paris, special flights were made between London and Paris during Jul. In August the regular service opened when Lt. E.H.Lawford left Hounslow carrying one passenger, a package of newspapers, a supply of leather, several brace of grouse, and some jars of Devonshire cream.

Lt. Lawford landed at Le Bourget, Paris, and set out for the return flight to Hounslow one hour later. The 216 miles between London and Paris were covered by the DH.4a in two hours 30 minutes on the outward journey and two hours five minutes on the return. The fare for a single journey was twenty guineas. A.T.&T. advertised one flight in each direction each day. In the first month, only two of the fifty-six flights were cancelled.

It was also used by Handley Page Transport Ltd and the Belgian airline SNETA. In the USA, a number, acquired by the US Post Office Department in 1919 and converted as mailplanes, remained in use until 1927. Canada, which received 12 of the aircraft as an ‘Imperial Gift’ from Britain, used them for spotting forest fires.

Variants:
Airco D.H.4A
Designation of British post-war civil conversions with an enclosed two-seat passenger cabin formed from the aft cockpit

DH-4A
Designation of US-built version with revised and increased capacity fuel system.

DH-4B/-4C/-4L/-4M/-4Amb/-4Ard
Blanket designation covering a large number of US post-war variants; for example, DH-4B variants included DH-4B, DH 4B-1, DH-4BD etc., to the extent of some 60 versions, many of them experimental.

Airco D.H.4R
Designation of a singe racing version converted by clipping the lower wings and installing a 336 kW (450-hp) Napier Lion inline piston engine

Gallery

Specifications:

Airco D.H.4
Engine: BHP, 200 hp
Wingspan: 42 ft 4.5 in / 12.9 m
Length: 30 ft 8 in / 9.3 m
Height: 10 ft 1 in / 3.0 m
Empty weight: 2197 lb / 996 kg
Loaded weight: 3386 lb / 1535 kg
Max speed: 108 mph / 173 kph
Ceiling: 17,500 ft / 5334 m
Endurance: 3 – 4.5 hr
Armament: 2 x .303 Lewis mg
Bombload: 2 x 230 lb or 4 x 112 lb

Airco D.H.4
Engine: Siddeley Puma, 230 hp
Wingspan: 42 ft 4.5 in / 12.9 m
Length: 30 ft 8 in / 9.3 m
Height: 10 ft 1 in / 3.0 m
Empty weight: 2230 lb / 1011 kg
Loaded weight: 3344 lb / 1516 kg
Max speed: 106 mph / 171 kph
Ceiling: 17,400 ft / 5324m
Endurance: 3 – 4.5 hr
Armament: 2 x .303 Lewis mg
Bombload: 2 x 230 lb or 4 x 112 lb

Airco D.H.4
Engine: Galloway Adriatic, 230 hp
Wingspan: 42 ft 4.5 in / 12.9 m
Length: 30 ft 8 in / 9.3 m
Height: 10 ft 1 in / 3.0 m
Empty weight: 2209 lb / 1002 kg
Loaded weight: 3641 lb / 1651 kg
Endurance: 3 – 4.5 hr
Armament: 2 x .303 Lewis mg
Bombload: 2 x 230 lb or 4 x 112 lb

Airco D.H.4
Engine: RAF 3A, 200 hp
Wingspan: 42 ft 4.5 in / 12.9 m
Length: 30 ft 8 in / 9.3 m
Height: 10 ft 1 in / 3.0 m
Empty weight: 2304 lb / 1044 kg
Loaded weight: 3340 lb / 1515 kg
Max speed: 122 mph / 196 kph
Ceiling: 18,500 ft / 5638 m
Endurance: 3 – 4.5 hr
Armament: 2 x .303 Lewis mg
Bombload: 2 x 230 lb or 4 x 112 lb

Airco D.H.4
Engine: Fiat A.12, 260 hp
Wingspan: 42 ft 4.5 in / 12.9 m
Length: 30 ft 8 in / 9.3 m
Height: 10 ft 1 in / 3.0 m
Empty weight: 2306 lb / 1045 kg
Loaded weight: 3360 lb / 1524 kg
Max speed: 114 mph / 183 kph
Ceiling: 17, 000 ft / 5181 m
Endurance: 3 – 4.5 hr
Armament: 2 x .303 Lewis mg
Bombload: 2 x 230 lb or 4 x 112 lb

D.H.4
Engine: Liberty 12
Wingspan: 42 ft 4.5 in / 12.9 m
Length: 30 ft 8 in / 9.3 m
Height: 10 ft 1 in / 3.0 m
Empty weight: 2391 lb / 1084 kg
Loaded weight: 3297 lb / 1949 kg
Max speed: 124 mph / 199 kph
Ceiling: 17,500 ft / 5334 m
Endurance: 3 – 4.5 hr
Armament: 2 x .303 Lewis mg
Bombload: 2 x 230 lb or 4 x 112 lb

Airco D.H.4
Engine: Rolls-Royce Mk. I, II, II, 250 hp
Wingspan: 42 ft 4.5 in / 12.9 m
Length: 30 ft 8 in / 9.3 m
Height: 10 ft 1 in / 3.0 m
Endurance: 3 – 4.5 hr
Armament: 2 x .303 Lewis mg
Bombload: 2 x 230 lb or 4 x 112 lb

Airco D.H.4
Engine: Rolls-Royce Mk. I, II, 275 hp
Wingspan: 42 ft 4.5 in / 12.9 m
Length: 30 ft 8 in / 9.3 m
Height: 10 ft 1 in / 3.0 m
Empty weight: 2303 lb / 1044 kg
Loaded weight: 3313 lb / 1502 kg
Max speed: 119 mph / 191 kph
Endurance: 3 – 4.5 hr
Armament: 2 x .303 Lewis mg
Bombload: 2 x 230 lb or 4 x 112 lb

DH.4
Engine: Rolls Royce Eagle III, 250 hp
Length: 30.7 ft / 9.23 m
Wing span: 42.3ft / 12.9m
Weight empty: 2,303 lb / 1,044 kg
Gross weight: 1503 kg / 3313 lb
Max speed: 119 mph / 190 kph
Ceiling: 16,000 ft / 4,900 m
Seats: 2
Armament (Standard version): One fixed machine gun firing forward
One or two free guns in the rear cockpit.
Armament (R.N.A.S. aircraft): Two fixed machine guns firing forward
One or two free guns in the rear cockpit
Max. bomb; load 460 lb / 210 kg

DH.4
Engine: 1 x 250hp Rolls-Royce Eagle VI inline engine
Wingspan: 12.92 m / 42 ft 5 in
Length: 9.35 m / 30 ft 8 in
Height: 3.35 m / 10 ft 11 in
Empty Weight: 2,392lbs (1,085kg)
Max take-off weight: 1575 kg / 3472 lb
Max. speed: 230 km/h / 143 mph / 124kt
Maximum Range: 478miles / 770km
Rate-of-Climb: 1,000ft/min (305m/min)
Ceiling: 6705 m / 22000 ft
Crew: 2
Armament: 2 x 7.62mm Vickers machine-guns, 209kg of bombs
Maximum External Bomb Load: 460 lbs.

Airco D.H.4
Engine: Rolls-Royce Eagle VIII, 280 kW / 375 hp
Wingspan: 42 ft 4.5 in / 12.9 m
Wing area: 40.32 m / 434 sq.ft
Length: 30 ft 8 in / 9.3 m
Height: 10 ft 1 in / 3.0 m
Empty weight: 2387 lb / 1082 kg
Loaded weight: 3472 lb / 1574 kg
Max speed: 143 mph / 230 kph
Service ceiling: 6705 m / 22,000 ft
Climb to 1830m / 6,000 ft: 4 minutes 50 sec
Endurance: 3 hours 45 min
Armament: one (RFC) or two (RNAS) fixed forward-firing 7.7 mm (0.303-in) Vickers machine-guns and one or two 7.7-mm 1(.303-in) Lewis gone in aft cockpit.
Bombload: 2 x 230 lb or 4 x 112 lb

Airco D.H.4R
Engine: Naper Lion 336 kW / 450-hp
Maximum level speed: 241 km/h / 150 mph
Empty weight: 1129 kg / 2490 lb
Maximum take off weight: 1447 kg / 3,191 lb
Length: 8.36 m / 27 ft 5in

De Havilland DH-4B
Manufacturer: Dayton-Wright Airplane Co.
Engine: Liberty V-12 water-cooled, 400-hp
Wingspan: 13.0 m / 42 ft 8 in
Length: 9.3 m / 30 ft 5 in
Height: 3.2 m / 10 ft 6 in
Empty weight: 1,087 kg / 2,391 lb
Gross weight: 1,953 kg / 4,297 lb
Seats: 2
Armament: two 7.62 mm (0.3 in) Marlin forward firing machine-guns
Airframe: Wood
Covering: Fabric

A conventional two ¬bay biplane of pusher configuration, the fuselage was curved along the front and top surfaces with slab sides and a flat underside – and held the armament, pilot, controls, fuel and engine. The pilot sat in an open-air cockpit “tub”. A single machine gun was fitted to the front of the fuselage. Fuel was held directly aft of the pilot in one tank, and ahead of the engine, the latter mounted to the extreme end of the fuselage rear with a two-blade wooden propeller. Wings were in a two-bay with parallel struts additionally held by cabling. Both upper and lower wings sported slight dihedral. The empennage tapered off to become a single vertical tail fin with a high-mounted horizontal plane affixed. The undercarriage was fixed in place and featured two large main landing gear wheels attached to the fuselage underside. The rear of the aircraft was supported by a simple tail skid.

Armament consisted of a single semi-trainable .303 Lewis type machine gun fed by a 47-round drum magazine. The machine gun could be mounted within three pre-set positions, allowing the pilot to fix the weapon at advantageous angles of fire. This proved highly impractical once in action. These three pre-set positions became largely ignored as most pilots soon learned to fix the machine gun in place and aim the entire aircraft at the intended target instead. Major Lance Hawker produced a fixed clip and even revised the gunsight for improved accuracy by allowing for leading of the target. Once enacted, the new clip and gunsight – along with the fixed machine gun – lessened the pilot’s workload substantially.

The prototype first flying in 1915, it began powered by a 100 hp Gnome Monosoupape engine. After trials in Britain, the prototype was issued to No 5 squadron RFC in France for further testing by July of 1915, but was destroyed following enemy action on August 9, 1915.

The D.H.2 was considered worthy of series production and initial deliveries began in late 1915 to No 24 Squadron, which was sent to France in February 1916 with 12 D.H.2s as the first ever British squadron to be equipped with single seat fighters.

With its small speed range and sensitive controls the D.H.2 caused some handling problems for pilots initially, but it was accepted as a highly manoeuvrable little fighter.

Modifications were made to the nose of the nacelle; the ammunition was carried in drums on external racks on each side of the cockpit; and the revised fuel system comprised a gravity tank fitted either under or on top of the upper mainplane on the port side. Production models retained the Gnome engine, as comparative trials with a 110 hp Le Rhone 9J powerplant revealed that this gave an inferior performance.

At least one DH.2 fell to German guns, but within time, she formed the ranks of No. 24 Squadron who first netted an aerial victory with a DH.2 on April 2nd, 1916. The DH.2 essentially became the Royal Flying Corps (RFC) first “true” dedicated fighter platform.

The first Imperial German Monoplane was downed by a DH.2 on April 25th, 1916. In June alone, DH.2 pilots racked up a further 17 enemy aircraft. A further 15 were counted in August and another 15 were netted in September. Ten more enemy aircraft were tallied in November.

Along the Western Front, the DH.2 had met her match by the new breed of German and Austro-Hungarian fighter by December 1916. On December 20th, 1916, five out of six DH.2s were lost in one aerial fight against just five Albatros D.III series fighters. Phasing out of the D.H.2 began in France in March 1917, though D.H.2s serving in Palestine with No 11 Squadron, and with No 47 Squadron and a joint RFC/RNAS squadron in Macedonia, had a slightly longer service life. Two were evaluated at Home Defence stations in Britain in 1917 but were unable to cope with the Zeppelin raiders.

No fewer than 100 DH.2s were retained on the British mainland to help train a new generation of fighter pilot, where they served until 1918. By the fall of 1918, the DH.2 was officially retired from any active service with the RFC.

The RFC remained the sole operator of the DH.2. She served within squadrons No.5, No.11, No.17, No.18, No.24, No.29, No.32, No.41, No.47 and No.111.

In total 453 D.H.2 were built.

Replica:
Mason DH 2

Airco DH.2
Engine: 1 x Gnome Monosoupape, 100hp
Wing span: 8.61 m / 28 ft 3 in
Length: 7.68m / 25 ft 2½ in
Height: 2.91 m / 9 ft 6½ in
Wing area: 23.13 sq.m / 249 sq.ft
Empty weight: 423 kg / 943 1b
Loaded weight: 654 kg / 1,441 lb
Fuel capacity: 26.3 gallon
Maximum level speed at sea level: 150 km/h / 93 mph / 81 kt
Maximum Range: 249 miles / 400km
Endurance: 2 hours 45 minutes
Rate-of-Climb: 545ft/min / 166m/min
Climb to 1830m /6,000ft: 11 minutes
Service Ceiling: 14,000 ft / 4270 m
Armament: 1 x 7.62mm forward-firing Lewis machine gun on flexible mount.
Crew: 1

Airco DH.2
Engine: 1 x Le Rhone 9J, 110 hp
Wing span: 8.61 m / 28 ft 3 in
Length: 7.68m / 25 ft 2½ in
Height: 2.91 m / 9 ft 6½ in
Wing area: 23.13 sq.m / 249 sq.ft
Empty weight: 455 kg / 1004 1b
Loaded weight: 702 kg / 1547 lb
Maximum level speed at sea level: 143 km/h / 92 mph
Maximum Range: 249 miles / 400km
Endurance: 2 hours 45 minutes
Rate-of-Climb: 545ft/min / 166m/min
Climb to 1830m /6,000ft: 11 minutes
Service Ceiling: 14,000 ft / 4270 m
Armament: 1 x 7.62mm forward-firing Lewis machine gun on flexible mount.
Crew: 1

Airco DH.2
Engine: 1 x Clerget 9Z, 110 hp
Wing span: 8.61 m / 28 ft 3 in
Length: 7.68m / 25 ft 2½ in
Height: 2.91 m / 9 ft 6½ in
Wing area: 23.13 sq.m / 249 sq.ft
Empty weight: 428 kg / 943 1b
Maximum take-off weight: 654 kg / 1,441lb
Maximum level speed at sea level: 150 km/h / 93 mph / 81 kt
Maximum Range: 249 miles / 400km
Endurance: 2 hours 45 minutes
Rate-of-Climb: 545ft/min / 166m/min
Climb to 1830m /6,000ft: 11 minutes
Service Ceiling: 14,000 ft / 4270 m
Armament: 1 x 7.62mm forward-firing Lewis machine gun on flexible mount.
Crew: 1

Geoffrey de Havilland was hired by the Airco firm in June of 1914 as lead designer and began developing the Airco “DH.1”. The DH.1 was a two-seat reconnaissance scout biplane fitted with a water-cooled inline engine in a “pusher” arrangement.

Geoffrey de Havilland piloted the prototype DH 1 fighter and reconnaissance aircraft on its first flight in early 1915. A two seat pusher biplane with the observer in the front cockpit, which also housed a forward firing machine gun, the DH 1 was powered by a 70 hp Renault engine, instead of the originally specified 120 hp Beardmore powerplant and the War Office ordered 49 examples. Appearing at the beginning of 1915, it was tested by Geoffrey de Havilland. Airco was fully committed to building Farman aircraft and employed a sub-contractor, Savages Ltd of Kings Lynn, but because of their inexperience, production of the DH.1 was delayed. An order for 100 was placed with Savages of Kings Lynn and production models differed from the prototype in having dual controls, a modified nacelle, reinforced brac¬ing wires and a simplified undercarriage.

Beardmore engines eventually became more plentiful and with this engine the type was designated DH.1A. With an all up weight increase of nearly 136 kg (300 lb), including a 10% additional fuel load, it was 13 km/h (8 mph) faster than the DH 1 and had a more rapid rate of climb.

At the end of 1915, the first five DH.1s off the production line had been alloated to training units. The remainder of the first batch were fitted with the 120 hp Beardmore and re-designated DH.1a.

Six DH.1a from the first batch saw service in the Middle East, and a further 44 were assigned to Home Defence units. No 14 Squadron had six DH1As which were operational in Palestine from the summer of 1916 on escort duty. The second batch of 49 was again built by Savages Ltd, but only 73 of the total number saw service with RFC units. Some survived in Britain until 1918, but all had been withdrawn from service before the Armis¬tice.

DH 1
Engine: Renault, 70hp
Span: 12.50 m / 41 ft 0 in
Length: 8.82 m / 28 ft 11.25 in
Height: 3.4 m / 11 ft 2 in
Empty weight: 615 kg / 1354 lb
Loaded weight: 927 kg / 2044 lb
Maximum speed: 132 km/h / 80 mph
Ceiling: 4114 m / 13,500 ft
Endurance: 4 hr

DH 1A
Engine: Beardmore, 120hp
Span: 12.50 m / 41 ft 0 in
Length: 8.82 m / 28 ft 11.25 in
Height: 3.4 m / 11 ft 2 in
Empty weight: 1610 lb / 730 kg
Loaded weight: 2340 lb / 1061 kg
Maximum speed: 144 km/h / 90 mph
Ceiling: 4114 m / 13,500 ft
Endurance: 4 hr

DH 1A
Engine: Austro-Daimler, 120hp
Span: 12.50 m / 41 ft 0 in
Length: 8.82 m / 28 ft 11.25 in
Height: 3.4 m / 11 ft 2 in
Empty weight: 1610 lb / 730 kg
Loaded weight: 2340 lb / 1061 kg
Maximum speed: 144 km/h / 90 mph
Ceiling: 4114 m / 13,500 ft
Endurance: 4 hr