|
|
The Blackburn Beagle was a day bomber, torpedo bomber and long range reconnaissance aircraft that only reached the prototype stage.
Work on the Beagle began in response to Air Ministry Specification 24/25, which called for a high altitude bomber which could also be used as a coastal defence torpedo bomber. The bomber version would carry a lighter military load and have higher performance while the torpedo bomber would sacrifice performance in order to carry the heavier torpedo.
In March 1926, before the drawings for the original design had been completed, the design had to be modified to meet a revised specification 23/25 (of 18 January 1926). The new requirement called for a single engined day bomber which could also operate as a long range reconnaissance aircraft or as a torpedo bomber.
Blackburn produced a design for a single bay biplane, similar in appearance to the existing Blackburn Ripon IIF. The fuselage was built around a steel tube structure in the centre fuselage, which ended in an engine bearer plate. The rear fuselage was build around four spruce longerons braced with steel tile rods. At the very rear the last fuselage bay was built with a tubular steel framework in order to carry the weight of a mechanism to alter the tailplane incidence. At first Blackburn looked at using the 495hp Bristol Orion engine, a new supercharged version of the Bristol Jupiter, but this engine failed its bench tests. As a result Blackburn moved onto the 460hp Bristol Jupiter VIIIF air cooled radial. It could also use the Napier Lion XI or Rolls-Royce F.XII. The engine was carried in a streamlined nose, with the tips of the cylinders emerging into the air.
The wings were single-bay, equal span and staggered, with the same amount of dihedreal on upper and lower wings. They were slightly swept back, had four Frise ailerons and wing tip slots. They were built around spruce spars and ribs, with duralumin compression struts and steel tie rods. They were linked by faired tubular steer struts and streamlined wires. The outer panels could be removed from the centre section for easier storage.
The two crew cockpits were close together. The pilot had controls for arming and releasing the torpedo. The gunner was also the bomb aimer, and had a prone bombing position under the pilot’s cockpit. This contained a bomb sight, bomb fusing and bomb release controls. This position also had an airspeed indicator, altimeter and a auxiliary rudder control handle to allow the bomb aimer to make last minute course corrections.
It had a divided undercarriage, to allow the torpedo to be carried below the fuselage. Between the undercarriage legs was a mounting that could carry either a 185 gallon auxiliary fuel tank for the reconnaissance role or an 18in naval torpedo. The Beagle was also armed with a forward firing Vickers gun mounted on the port side of the pilot’s cockpit and a flexibly mounted Lewis gun in the rear cockpit.
The prototype Beagle made its maiden flight at Brough on 18 February 1928. As a result of its early flights it was given a modified rudder. It remained at Brough until July 1929 when it went to the A&AEE at Martlesham Heath for competitive trials against the Gloster Goring, Handley Page Hare, Westland Witch and Hawker Harrier.
None of these aircraft met the performance requirements. The Beagle was returned to Blackburn, who made a number of changes to it. It was given a geared and supercharged 590hp Bristol Jupiter XF radial engine in a new cowling that left more of the engine cylinder exposed, improving the air cooling. The modified aircraft went back to Martlesham Heath on 19 March 1931, by which time any change of a production order was long gone (the Vickers Vildebeest had been put into production instead, satisfying the torpedo bomber requirement). It later went to the Development Squadron at Gosport. On 2 November 1931 it was flown to the RAE and Farnborough, and it was then returned to Blackburn for an overhaul. It was recorded as having been flown at Brough on 6 June 1932, and landing at the de Havilland airfield at Stag Lane, Edgware, on 3 October 1932, and then disappeared from the record.
Book 245
Engine: Bristol Jupiter VIIIF
Power: 460hp
Crew:
Span: 45ft 6in
Length: 33ft 1in
Height: 11ft 9in
Tare weight: 3,495lb
All-up weight: 6,120lb (bomber)/ 7,500lb (torpedo bomber)
Max speed at 5,000ft: 140mph (bomber)/ 133mph (torpedo bomber)
Climb Rate: 740ft/ min (bomber)/ 370ft/ min (torpedo bomber)
Service ceiling: 16,000ft/ 11,200ft
Endurance: 3.5 hours