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Aviation History
1936
1936 - 0643.PDF
282 FLIGHT. MARCH 12, 1936, PROTECTION for PORTUGAL Six Blackburn Shark Seaplanes Undergo Acceptance Trials : High Perjormance with Heavy and Varied Loads W ITH a whistling and growling, a strangely-marked seaplane, its lower wings decked with bombs, dropped low over the Humber, skimmed past the Blackburn works and climbed away into the dis tance. Someone said that " Dasher had finished his eight- eight-hundred show," which meant that Flt.-Lt. A. M. Blake had completed the trials with full bomb load and at an all-up weight, actually, of 8,7501b., of a Shark sea plane before representatives of the Portuguese Naval Air Service. These gentlemen—Lt. Cdr. Ayres de Sousa, Lt. Cdr. Telles Pacheio and Lt. Faria by name—have been at Brough supervising the acceptance tests of half a dozen of these amazingly versatile machines, and it was in con nection with these tests that one was privileged to witness a demonstration. Blackburns secured the contract in competition with twenty-one firms. Although the Shark, as employed by our own Royal Air Force, is normally a deck-landing torpedo spotter reconnaissance type with wheel under carriage, Portugal will use her new machines purely as seaplanes, mainly lor reconnaissance and bombing. Torpedo dropping will not form part of their normal duties, although three of them have torpedo carriers. As seen at Brough, one was fitted with a long-range fuel tank beneath the fuselage (one might almost call the water-tight metal monocoque structure of the Shark a hull) and another had Marconi wireless apparatus. With normal tankage of 171 gallons the Shark has a range, carrying reconnaissance load, of 690 miles, but with the extra " torpedo" tank in position (this holds 160 gallons) it will fly for about 1,140 miles. Each of the Portuguese machines is fitted with an Arm strong Siddeley Tig^r Vic fourteen cylinder two-row moderately supercharged radial. This model is a special de-rated adaptation of the Tiger VI now being mounted as standard in Royal Air Force Sharks. It runs on fuel of considerably lower cctane number than the Service " 87," and its An observer tries the high speed Vickers- Berthier gun on one of the Sharks compression ratio has been lowered in consequence from 6.2 to 5.35. At normal r.p.m. it delivers 700 h.p. (the Tiger VI is rated at 760 h.p.), but for take-off, at plus 2|lb. boost, 746 h.p. is available. Sqn. Ldr. J. L. N. Bennett-Baggs, a director of the Blackburn Company, gave a demonstration of one of the machines equipped for reconnaissance and carrying no pro jectile load. The all-up weight in this case is 7,9431b. While running up the Tiger on the tarmac he fired a burst from his front synchronised Vickers gun, and on entering the water his observer " cut loose " with the compact little Vickers-Berthier on the Fairey mounting in the rear cockpit. This gun, incidentally, is a new gas-operated type with a sixty-round drum and a rate of fire of over 900 rounds a minute. The water was as smooth as the proverbial mill pond, and quick, spectacular take-offs were not, in consequence, the order of the day. In the air, however, the machine flown by Sqn. Ldr. Bennett-Baggs behaved in a decidedly lively fashion for one of its calibre, performing really hectic dives, zooms and " shootings-up." Obviously the float undercarriage does not detract so greatly from the Shark's performance as might reasonably be supposed. Actually, the difference in speed between the torpedo bomber sea plane and torpedo bomber ship-plane versions is about 9 m.p.h. The "Boots" The seaplane undercarriage is of quite unusual interest. It is attached to the same fuselage and wing root joints as the wheel undercarriage, two additional attachment points being provided in the forward part of the fuselage. There is a cross strut between the floats at the front joints and wire bracing is employed only in the front truss. The floats, which incorporate shock-absorbing devices at their points of attachment, are of Blackburn design and con struction, and are made of Alclad. It is possible to inter change one with the other. The water rudders are oper ated pneumatically by the system which actuates the wheel brakes on the landplane model. This arrangement is an invention of the Blackburn company, and not only obviates the complication of a cable control, but provides a control system which cannot affect the air rudder in the event of failure or damage. The fitting of float undercarriage does not preclude the employment of the Shark for dive bombing, which work it will perform with its full 1,500-lb. bomb load. This, incidentally, can be made up in a number of ways. Attach ments are provided for six bomb-carriers—four for bombs up to 250 lb. each and two for five-hundred-pounders. Then there are two small racks for practice bombs. The fusing controls are accessible to both pilot and observer and it is possible to release the bombs from front or rear cockpit. A course-setting bomb sight is fitted to a hinged mounting over the bombing hatch in the prone station. The torpedo carrier fitted to three of the Portuguese Sharks will take any normal type of torpedo up to a weight of about 1,500 lb. Blackburn mechanics gave a demonstration of how quickly the wings can be folded. Because of the rigid brac ing of the interplane struts the Shark's wings need no jury struts-when .felded. Fokling and-spreading operations re quire only two men and are accelerated by hydraulically
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