The Blackburn Blackburd was a torpedo bomber designed to be able to carry heavier torpedoes than the Sopwith Cuckoo, but that only reached the prototype stage and eventually lost out to the production of more Cuckoos.
The Sopwith Cuckoo was a successful aircraft, but it could only carry a 1,086lb torpedo, which wasn’t powerful enough to sink a large warship. In the autumn of 1917 the Admiralty issued a requirement for a new single seat torpedo bomber that could carry the 1,423lb Mk VIII torpedo, which carried a 50% larger warhead. This was given the specification N.1B (Torpedo-Carrying Ship Aeroplane) by the Admiralty, which became Type XXII under the new RAF system in April 1918. The new aircraft was expected to operate from the aircraft carrier HMS Argus, which was commissioned in September 1918.
In February 1918 orders were placed for three prototypes of the Short Shirl and three of the Blackburn Blackburd. All were to be powered by the Rolls-Royce Eagle VIII engine. In an attempt to make sure they won the contract Blackburn provided their aircraft for £2,200, two thirds of their real cost.
The Blackburd was designed by Harris Booth. It was a three bay biplane with unstaggered folding wings. The wings had a constant chord and uniform section throughout their length, to make them easier to produce. They had a wire trailing edge and were made with rectangular section box spars and three ply spruce rubs braced with steel tie rods. The fuselage was also simple in design, build around four rectangular spruce box longerons, with a square cross-section and the same depth along its entire length. It had four long span ailerons which could also be used as flaps during take off. The wing and undercarriage struts were one area of complexity – instead of using solid spruce the structural part were made of tubular steel, surrounded by a streamlined fabric structure. The aircraft thus looked very much like a simple flying box.
The undercarriage was somewhat unusual. The idea was that the aircraft would take off on wheels, but were carried on an axle, so would have to be dropped before the torpedo could be used. The aircraft would then land on skids. Experiments with the Sopwith Pup and Sopwith 1 ½ Strutter had proved this system would work.
The pilot’s cockpit was 9ft behind the centre section, and about half way between the back of the wing and the front of the tail, so forward visibility was poor. The aircraft was unarmed apart from the torpedo.
The first prototype was originally due to have been completed by 6 May 1918, but was delayed to the end of May by the need to shift men to production of the first Sopwith Cuckoos, being built by Blackburn. It was tested extensively over the Humber, carrying out a series of dummy torpedo drops. The skid landing system was also thus tested, and was said to be similar to landing a seaplane. The first prototype reached Martlesham Heath for official performance trials on 4 June 1918.
The results of these trials weren’t encouraging. The use of the ailerons as take-off flaps was criticized as it meant that the aircraft was uncontrollable laterally during take off, although they were very effective at reducing its take-off distance, taking it down to one third of the distance without them. It was nose heavy in flight, and could only be flown for long distances by using a bungee cord to keep the control stick in place. The rudder was too small, and didn’t work at low speeds. The aircraft crashed before the end of the trials, which did at least show that the structure was strong.
The second prototype was modified as a result of this report. It was given small wing tip floats. The tail was made stronger, with better hinges and a larger rudder with a new shape. It kept the long take off flaps but also had shorter ailerons which were controlled separately. A large rectangular tropical radiator was installed.
The second prototype was completed in August 1918, and went to RAF East Fortune in Scotland for torpedo trials. After servicing at Brough it went to Martlesham Heath for performance tests on 16 October. These were completed by 9 November, two days before the end of the war. This aircraft later joined the Development Squadron at Gosport, before being dismantled for spare parts.
The third prototype was completed in November 1918 and went straight to the Development Squadron. It rained operational for several years after the end of the war, and was used experimentally from HMS Argus in the Mediterranean.
The Blackburd lost out to the Shirl in the competitive performance tests, but Blackburn did at least win a contract to build 100 of the Shirls. However this was soon cancelled in favour of more Sopwith Cuckoos, so neither of the new torpedo bombers ever entered production.
Stats with torpedo
Engine: Rolls-Royce Eagle VIII
Span: 52ft 5in
Length: 34ft 10in
Height: 12ft 4.5in
Empty weight: 3,228lb
All-up weight: 5,700lb
Max speed: 90.5mph at 6,500ft
Climb Rate: 505ft/ in
Service ceiling: 11,000ft
Endurance: 3 hours
Bomb load: 1,423lb Mk VIII torpedo