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The Avro 504 was the first version of what became the most numerous British military aircraft of the First World War, used as a training aircraft throughout the war and into the early 1930s.
The Avro 504 was developed as a successor to the Avro 500, the company’s first military aircraft. Work on the design began in November 1912 and was completed early in 1913. The wings were designed by H.E. Broadsmith, the fuselage and undercarriage by Roy Chadwick (famous as the designer of the Lancaster) and Taylor.
The 504 had a box girder fuselage built around four straight ash longerons, with spruce cross struts. It had equal span two bay biplane wings with 2ft of stagger, braced with spruce interplane struts. The prototype used warping ‘ailerons’ rather than full wing warping, with the ailerons fixed at the inner end and warping at the outer end. The undercarriage had a central ash skid attached to the fuselage by steel V struts, and two undercarriage wheels on a simple steel tube axle. Each leg used bungee cord shock absorbers. It had a comma type rudder. It was powered by a 80hp Gnome rotary engine. The pilot sat in the rear cockpit, the observer in the front.
The first prototype was delivered to Brooklands on 17 September, flown for the first time on 18 September and came fourth in the 1913 Aerial Derby at Hendon on 20 September! Early flights showed the need for some changes. The warping ailerons were replaced with more standard constant chord fully moving ailerons and a more streamlined engine cowling was installed.
In this configuration the aircraft entered the Hendon-Brighton-Hendon race of November 1913 but was forced to land with a broken carburetor control, came second in the Shell Trophy Race on 15 November then went to Farnborough for its official trials at the end of the month. On 10 February 1914 it set a new British height record of 14,420ft. The prototype was then purchased by the Daily Mail, and used to give short passenger flights. It was also given interchangeable twin floats and was sometimes used as a seaplane. It was commandeered for the RFC at the outbreak of war but damaged beyond repair two days later.
In the summer of 1913 the War Office ordered twelve machines. The production aircraft had to have stronger wings, so the depth and width of the rear wing spar was doubled. The last of this batch were delivered in June 1914.
At the outbreak of war some of the Avro 504s were serving with No.5 Squadron, RFC, and went to France with the squadron on 13 August. One of these aircraft became the first to be brought down by the Germans, when the aircraft carrying Lt. V Waterfall and C.G.G. Bayly was hit by infantry fire over Germany on 22 August. In October another of the squadron’s Avros was given a Lewis gun and used to strafe a troop train. It also forced down an Albatros two seater in November. However the type was never a true front line aircraft, and the most in use with the RFC at any one time was only thirteen.
The standard Avro 504’s most famous military exploit came in the hands of the Admiralty. They had ordered one aircraft in the spring of 1914, followed a few months later by orders for six more. The first of these reached RNAS Eastchurch on 27 November and was used as a bomber. On 14 December an attempt to bomb the submarine depot at Bruges was foiled by poor weather and the Ostend-Bruges railway was bombed instead. However the most famous raid was the attack on the Zeppelin sheds at Friedrichshafen on 21 November 1914. A special flight of four aircraft was formed at Manchester in October 1914, commanded by Squadron Commander P. Shepherd. They were sent to Belford by train, arriving on the night of 13 November.
Three of the four machines successfully took off early on 21 November, each carrying four 20lb bombs. They were able to follow the Rhine to Lake Constance, and bombed the airship sheds. They narrowly missed Zeppelin L.7 but did hit a gas plant, which exploded. Sqn Cdr E. Featherstone Briggs was shot down, but the other two aircraft returned to base safely. One of the aircraft took part in two raids on Ostend, and a 24 March 1915 raid on U-boat pens near Antwerp in which two U-boats were destroyed. Three of the aircraft survived to return to Britain to be used as trainers.
Once it was clear that the aircraft was mainly to be used as a trainer, Avro developed a self contained dual control unit made up of the two seats, two sets of control columns and rudder bars. Early aircraft were converted to the training role, but later machines fro a second batch of 44 ordered by the War Office were built as trainers.
At least 62 Avro 504s were built – the prototype, four for Avro, 12 in the initial War Office order and 44 in a second batch and one for the Admiralty. The six ordered for the Friedrichshafen raid came from the second War Office batch. Work then moved onto the Avro 504A for the RFC and the Avro 504B for the RNAS. The lack of an mark number or letter for this initial version of the aircraft can cause some confusion, with the Avro 504 being used both for these first sixty or so aircraft and for the entire family of aircraft.
Engine: Gnome or Le Rhone or A.B.C.
Power: 80hp or 80hp or 80hp
Crew: 2
Span: 36ft 0in
Length: 29ft 5in
Height: 10ft 5in
Tare weight: 924lb (land plane) 1,070lb (seaplane)
All-up weight: 1,574 (land plane), 1,719lb (seaplane)
Max speed: 82mph (land plane), 75mph (seaplane)