Blackburn Botha

The Blackburn B.26 Botha was a four-seat reconnaissance and torpedo bomber. It was produced by the British aviation company Blackburn Aircraft at its factories at Brough and Dumbarton.

The Botha was developed during the mid 1930s in response to Air Ministry Specification M.15/35, and was ordered straight off the drawing board alongside the competing Bristol Beaufort. On 28 December 1938, the first production aircraft made the type's maiden flight; almost exactly one year later, it entered service with the RAF. During official evaluation testing of the Botha, stability issues were revealed, as well as the fact that it was underpowered. It was only briefly used in frontline operations before being withdrawn to secondary roles during 1941. It continued to be flown in these roles, largely being used for training and as a target tug, before being fully withdrawn in September 1944.

During September 1935, the British Air Ministry issued specification M.15/35, which called for a new reconnaissance/torpedo bomber to reequip RAF Coastal Command. Among the stipulations set out were a twin-engined arrangement, a crew of three, and the provision of internal stowage to accommodate a single torpedo. Blackburn opted to produce a design to meet this requirement. During early 1936, two submissions that fulfilled this requirement were accepted, one being Blackburn's and the other being the Type 152 from Bristol. The Blackburn design would receive the name Botha after General Botha, while the rival Type 152 would be named Beaufort after the Duke of Beaufort.

Both of the proposed aircraft were originally intended to be powered by the Bristol Perseus radial engine, capable of producing 850 hp (634 kW). At a late stage, the Air Ministry decided to revise the specification and re-issue it as M.10/36; the principal change was that the aircraft was abruptly required to accommodate a crew of four, along with an enlarged fuselage that increased the aircraft's overall weight. It was also intended that this change would allow the successful design to be ordered straight from the drawing board. A consequence of the weight increase was that both designs suddenly required more power to be able to achieve their envisioned performance; however, while the Taurus, capable of producing up to 1,130 hp (840 kW), was provided for the Beaufort, the Botha only received the Perseus X, capable of up to 880 hp (660 kW), due to limited supplies of the Taurus engine.

Early on, Blackburn made several proposals to address the engine shortfall; the adoption of the large Bristol Hercules radial engine was the main element of the proposed Botha II, however, it was not pursued. During December 1936, the Air Ministry ordered 442 Bothas, it placed orders for the competing Beaufort as well. Immediately upon receipt of the order, Blackburn set about establishing two production lines for the Botha at its main factory at Brough and its new facility in Dumbarton, Scotland; additional component manufacturing was performed at the Olympia works in Leeds.

On 28 December 1938, the first flight of the Botha took place at Brough , piloted by H. Bailey. This was the first production aircraft, since there was no prototypes as such. On 25 March 1939 it was delivered to RAF Martlesham Heath for performance and handling trials by the Aeroplane and Armament Experimental Establishment (A&AEE). The first production aircraft was found to have inadequate elevator control; this was rectified on a second aircraft sent for trials by a slight increase in the tailplane area and a larger horn-balanced elevator.

A total of 380 aircraft were produced at Brough, while another 200 Bothas were constructed at Dumbarton for a total of 580. Peak production was attained in June 1940, during that month alone the two sites produced 58 aircraft. Limited modifications were implemented during the production run, such as the addition of a jettisonable main entrance door, non-retractable bulged navigator windows, new flap jacks, and an improved undercarriage retraction mechanism; several proposed changes, such as larger propellers and flame dampers, were not implemented.

In basic configuration, the Blackburn Botha was a twin-engined cantilever monoplane; the high-mounted wing was a deliberate design decision, intended to provide the best possible downward view for its crew. The pilot, seated in a relatively spacious and well-instrumented cabin at the front of the aircraft, had an exceptionally unobstructed forward-facing field of view, although the rearwards view was restricted by the position of the engines. The navigator and wireless operator's positions were within a separate central cabin reached via an entrance door with a built-in stepladder on the starboard side of the fuselage. Crew members could move between their positions via a narrow gangway; the observer had to use this passage to reach the prone bombing position in the aircraft's nose. The final crew member, the gunner, was positioned to the rear of the wing in an egg-shaped power-assisted turret on the upper fuselage.