06/30/2010. Remarks by Johan Visschedijk: "Specification 10/36 of June 30, 1936, represented the amalgamation of Specifications M.15/35 for an experimental shore-based torpedo-bomber and G.24/35 for an experimental general-purpose reconnaissance landplane, and Specifications 10/36 stipulated that the combination of the pair of previous specifications was to be without detriment to either, the resulting aircraft to carry a crew of four, consisting of two pilots, one W/T (Wireless/Telegraph) operator and one air gunner. A single fixed gun was to be installed for the pilot, two guns being provided in the rear turret. As an alternative to a torpedo, the Specifications 10/36 machine was to accommodate a 2,000 lb (907 kg) AP (Armor Piercing) bomb.

The Botha G.R.Mk.I was ordered into production 'straight off the drawing board' to Specifications 10/36. Designed to Specifications M.15/35 for Blackburn by G. E. Petty, the Botha was to exhibit such shortcomings that it was withdrawn after only a brief spell on operations. Contracts for 486 aircraft being placed in December 1936, but it took over two years before the pair of prototypes, s/n L6104 and L6105, made their maiden flights in the spring of 1939, followed by the first production Botha I in July 1939.

In appearance the Botha was a clean and quite attractive high-wing monoplane of stressed-skin construction. Alternative engines fitted were two 880 hp Perseus Xs or 930 hp Perseus XAs, and the Botha was armed with a single fixed 0.303 (7.7 mm) gun for the pilot and a pair of 0.303 (7.7 mm) guns in a power-driven dorsal turret. The high-wing layout facilitated housing of the torpedo internally without making it necessary to deepen the fuselage inordinately.

Meanwhile, a second production line had been started at the Scottish factory of Blackburn Aircraft at Dumbarton, where the first Botha was due to be delivered in August 1939. Production orders finally totaled 578, the serial numbers allocated being L6106-L6345, L6347-L6546, W5017-W5056, W5065-W5114, W5118-W5157 and W5162-W5169. Additional production of the Botha by Boulton Paul was planned to Specification 39/36, and Specification 45/36 was drawn up for further production by Blackburn, but neither project was proceeded with.

The Botha was just too late to reach Coastal Command squadrons by the outbreak of war. Superseding Avro Ansons, first deliveries were made to No. 608 (North Riding) Squadron of the Auxiliary Air Force at Thornaby in October 1939. The Botha became the first Blackburn aircraft to serve with a land-based squadron of the RAF since the Kangaroos of No. 246 Squadron in 1918. Some Bothas also went to No. 502 Squadron at Aldergrove.

The Botha was seriously underpowered and its shortcomings were such that the type was not issued to other squadrons, as had been planned, but continued to serve with No. 608 Squadron, chiefly on patrols over the North Sea, until April 1941, when they were finally withdrawn from operational flying. It was subsequently employed in operational training duties, mainly with Air Navigation and Air Gunnery Schools. It remained active in this role until 1944.

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As other aircraft, the Botha was subject of structural tests.

MAEE Helensburgh Report H/A/295 of July 16, 1942, dealt with flotation and drop tests conducted with a Botha at the Blackburn Clyde factory at Dumbarton to investigate the machine's strength under drop conditions. The airframe had been modified after static tests at Brough, and trials were made at a loaded weight of about 14,000 lb (6,350 kg). It took 7 min to completely flood the undamaged fuselage, the aircraft continuing to float nose down on its buoyancy compartments in the outer wings and tail without sign of sinking.

During the flotation test the machine was lowered gently and allowed to sink freely, observers inside the fuselage noting its attitude and the influx of the water. The airframe employed in the trials consisted of a new fuselage and main structural and outer buoyant portions of the wings. Omitted were the leading edge of the wings and of the center section, the roof fairing from the cabin to the wings, the wing tips, ailerons, trailing edge, flaps, rudder and elevators. Concrete slabs replaced the engines and turret, 271 gal (1,026 l) of water ballast occupied the main fuel tanks, the oil tanks also were filled with water, and 50 lb. of ballast was stowed in the rear fuselage.

The drop test was made on three points from 2 ft 6 in (0.76 m) height, the Botha breaking its back on impact at the frame below the wings' leading edge. Accelerations recorded were 4G at the tail and 5G at the center section. It was concluded that the Botha needed strengthening at this frame before it could be regarded as strong enough for ditching. The drop disclosed that the bomb-bay doors were satisfactory and should assist in protecting the rear buoyancy compartment from damage. Damage was caused neither to the modified bomb-aimer's window nor to the stiffened Novellon nosepiece."