The Airco DH.6 was a British military trainer biplane used by the Royal Flying Corps during the First World War. Known by various nicknames, including the "Skyhook", the trainer became a widely used light civil aircraft in the postwar era.
The DH.6 was specifically designed as a military trainer, at a time when it was usual for obsolete service types to be used in this role. Geoffrey de Havilland seems to have had two design criteria in mind. The first was that it should be cheap and easy to build, and above all, simple to repair after the mishaps common in ab-initio training. The top and bottom wings were "brutally" square cut, and were interchangeable. (Hence the roundels in unconventional positions on many wartime photographs of the type.) They were heavily cambered, and braced with cables rather than streamlined wires. On the original version of the type there was no stagger. Even the rudder, on the prototype of the usual curved de Havilland outline, was on production machines cut square. The fuselage structure was a straight box with no attempt at refinement of outline – instructor and pupil sat in tandem on basketwork seats in a single cockpit that was Spartan even by the standards of the time.
The standard engine was the ubiquitous and readily available 90 hp (67 kW) RAF 1a. Because of its use in the B.E.2 the engine had the advantage of being very familiar indeed to RFC mechanics. It was stuck onto the front of the DH.6 in the most straightforward way possible, without any type of cowling, and the usual crudely upswept exhaust pipes of this type of engine were fitted. Eventually even stocks of the RAF 1a ran short, and various other engines were fitted to DH.6s, including the 90 hp (67 kW) Curtiss OX-5 and the 80 hp (60 kW) Renault.
This was an era when instructors in the RFC referred to their pupils as "Huns" (the term used for enemy airmen) and casualties at training schools were high. The second design criterion was that the new trainer should be "safe" to fly, both for a new pupil and his instructor. One way to obtain this safety was a "decouple" on the dual controls so that the instructor could take control at any time without having to wrestle with a panicking pupil.Another route to the desired safety was through the new trainer's flying characteristics. De Havilland's work at the Royal Aircraft Factory, where much basic research had been carried out into the nature of stability and control in aircraft, left him well qualified to design a "safe" aircraft. In the event, the DH.6 had very gentle flying characteristics; it was probably the most "forgiving" aircraft of its time, allowing itself to be flown "crab wise" in improperly banked turns, and being almost impossible to stall or spin, as it was able to maintain sustained flight at speeds as low as 30 miles per hour (48 km/h).
In fact, the DH.6 has been frequently described as "too safe" to make a good trainer; this referred to its gentle reaction to inexpert piloting rather than to excessive stability however, as it was designed with a degree of inherent instability about all three axes.
With the "Skyhook's" low power, strong but rather heavy construction and lack of streamlining, its maximum speed was naturally very low, even by the standards of the time.
At least 2,282 DH.6s were built in the UK during the war, out of orders totalling about 3,000. Besides Airco, batches were built by Grahame-White, Kingsbury, Harland and Wolff, Morgan, Savages, Ransomes, Sims & Jefferies, and Gloucestershire. A single DH.6 was constructed in July 1917 by Canadian Aeroplanes Ltd. as a prototype for projected production should availability of the Curtiss JN-4 prove inadequate; it was the first British-designed aircraft built in Canada. In in the event, there was no shortage of "Jennies", and it remained a one-off.
In 1917, training of RFC pilots began to receive a long overdue overhaul. The School of Special Flying at Gosport in Hampshire was established by Maj. Robert R. Smith-Barry with the aim of making flight instructors into specially trained experts - rather than entrusting the role to novices who had barely completed their own training, and operational pilots being "rested" to recover from combat fatigue. The Avro 504K was adopted as the standard trainer by the end of 1917, with the DH.6 becoming "surplus" as far as the training role was concerned.
At the end of 1917, about 300 DH.6s were transferred to the RNAS for anti-submarine patrols. While far from ideal for this work, the type proved surprisingly "seaworthy", being known to float for as long as ten hours after ditching. On operations, the underpowered trainer had to be flown solo, to allow a token bomb load to be carried. The "built in" instability designed to keep a student pilot alert proved tiring for pilots on long patrols over water, and experimental changes were made in mid-1918 to improve stability. These included the introduction of 10 in (25 cm) of back-stagger to wings of reduced chord and camber, with narrower elevators and rudder. DH.6s modified to this standard were unofficially dubbed "DH 6As".
Over 1,000 DH.6s were still in service in second line roles with the RAF at the end of the war.
Many RFC/RAF aircraft of this period received nicknames (some of which, like the "zoo" names of Sopwith types, reached semi-official status) but the DH.6 must hold the record for the number and variety of humorous but highly disrespectful epithets. The "skyhook", a favourite appellation of Australian airmen, probably referred to its lack of speed, although the shape of the exhaust pipes has also been mentioned. Other nicknames for the type included "crab," "clockwork mouse," "flying coffin" and "dung hunter" (these last two on account of the shape of the plywood cockpit, thought to resemble either a coffin or an outside toilet). The type's over-forgiving nature was probably behind yet another nickname, the "clutching hand," although this may also have been associated with its notorious lack of speed.
The aircraft, originally designated the F.K.7, was designed by Dutch aircraft designer Frederick Koolhoven as a replacement for the Royal Aircraft Factory B.E.2c and the Armstrong Whitworth F.K.3. It was a sturdier aircraft than the F.K.3, with a larger fuselage and wings and was powered by a 160 hp (110 kW) Beardmore water-cooled engine. The undercarriage used oleo shock absorbers. The undercarriage was unable to withstand rough use on the frontline airfields. The observer was equipped with a Scarff ring mounting for a 0.303 in (7.7 mm) Lewis machine gun. No armament was initially provided for the pilot. The rudder featured a long, pointed horn-balance.
In service the F.K.8s (nicknamed the "Big Ack") proved to be effective and dependable. It proved to be fairly successful in performing reconnaissance, artillery spotting, ground-attack, contact-patrol and day and night bombing missions. It was easier to fly than the R.E.8 and was sturdier but its performance was even more mediocre and it shared the inherent stability that plagued many Royal Aircraft Factory types.
A total of 1,650 were built and the type served alongside the R.E.8 until the end of the war, at which point 694 F.K.8s remained on RAF charge.
The F.K.8 served with several squadrons on operations in France, Macedonia, Palestine and for home defence, proving more popular in service than its better known contemporary the R.E.8. The first squadron was 35 Squadron. The F.K.8 was principally used for corps reconnaissance but was also used for light bombing, being capable of carrying up to six 40 lb (20 kg) phosphorus smoke bombs, up to four 65 lb (29 kg) bombs or two 112 lb (51 kg) bombs on underwing racks.
Two Victoria Crosses were won by pilots of F.K.8s; one by Second Lieutenant Alan Arnett McLeod of No. 2 Squadron RFC, on 27 March 1918 and the second by Captain Ferdinand Maurice Felix West of No. 8 Squadron RAF on August 10, 1918.
During World War I, the R.E.8 was the most widely used British two-seater biplane on the Western Front. A descendant of the R.E.7, it was initially developed for reconnaissance work but also saw service as a bomber and ground attack aircraft. Nicknamed "Harry Tate," it provided a stable platform for photographic missions but suffered from poor maneuverability, leaving it vulnerable to attack by enemy fighters.
The Royal Aircraft Factory Reconnaissance Experimental 8 (R.E.8) was a lumbering British two-seat biplane reconnaissance and bomber aircraft of the First World War. Intended as a replacement for the vulnerable B.E.2, the R.E.8 was much more difficult to fly, and was regarded with great suspicion at first in the Royal Flying Corps.
Although eventually it gave reasonably satisfactory service, it was never an outstanding combat aircraft. In spite of this, and heavy combat losses,the R.E.8 served as the standard British reconnaissance and artillery spotting aircraft from mid-1917 to the end of the war, serving alongside the rather more popular Armstrong Whitworth F.K.8. Over 4,000 R.E.8s were eventually produced and they served in most theatres including Italy, Russia, Palestine and Mesopotamia, as well as the Western Front.
The Sopwith 1½ Strutter was a British one or two-seat biplane multi-role aircraft of the First World War. It is significant as the first British-designed two seater tractor fighter, and the first British aircraft to enter service with a synchronised machine gun. It also saw widespread but rather undistinguished service with the French Aéronautique Militaire.
The first British fighter equipped with a fixed, forward firing, synchronized machine gun, the Sopwith 1½ Strutter was built in both one and two-seater models. In the latter version, the gas tank was dangerously positioned between the pilot and observer.
This design flaw prompted some airmen to joke that the designer of the aircraft must surely have been German. Not long after its introduction, the 1½ Strutter was replaced by the Sopwith Pup.
The Vickers F.B.14 was a British two-seat fighter/reconnaissance biplane designed and built by Vickers Limited. About 100 were built for the Royal Flying Corps but saw only limited use as it was designed for a larger engine which was not available when production commenced and it did not meet performance expectations.
The F.B.14 was a conventional single-bay biplane with two tandem open cockpits and a fixed tailskid landing gear. It was designed to use a new engine, the 230 hp (170 kW) BHP inline engine (later to become the Siddeley Puma). The steel-tube airframe was completed in mid-1916, but the engine was not ready and it was fitted with a 160 hp (120 kW) Beardmore engine instead. The aircraft was underpowered with the Beardmore engine and suffered reliability problems and over 50 production aircraft were delivered to the Royal Flying Corps without engines. A more reliable engine was tested, but the 120 hp (90 kW) Beardmore did not help meet the performance required. Attempts to fit alternate engines resulted in a number of variants with the most successful being a Rolls-Royce Eagle IV Vee engine. The aircraft performance was inferior to the contempary Bristol F.2B, however, and further development of the F.B.14 was abandoned.
The F.B.14 saw limited operational use, with some being sent to Mesopotamia, with seven being used in home defence Squadrons. The Rolls-Royce powered F.B.14D, while being used for testing of an experimental gunsight at Orfordness in July 1917, engaged a German air raid and claimed an unconfirmed shoot-down of a Gotha bomber off Zeebrugge.