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Aviation History
1945
1945 - 0720.PDF
FLIGHT APRIL 12TH, 1945 BLACKBURN miles long, on which traffic density might be fairly low. For some years past there have been but three specialists in flying boats in this country: Short Brothers, Saunders- Roe and Supermarinc. Blackburn Aircraft may be said to have retired from the designing field several years ago, but in the earlier days that company produced several flying boats, notably the Iris "family" Even in present times the firm has built Short Sunderlands on a large scale, so that obviously both design staff and workers are accus- tomed' to this class of aircraft. We are very glad that Major R. D. Rennie has not altogether ""given up hope. He has been Blackburn's chief seaplane designer for many years, and although little official encouragement has been given and but few draughtsmen can be spared from urgent war work, Blackburns have found it possible to get out a project for a six-engined transport flying boat. So far it remains merely a project, but at least it serves to focus attention on this class of aircraft. The aircraft is of orthodox general arrangement, but its great size will at once attract attention. A six-engined, high-wing monoplane with single fin and rudder, it has a gross weight of 310,000 lb. (138 tons) (compare this with the 22 tons of the Sunderland boat), and its wing span is 202ft., or nearly twice that of a four-engined bomber of to-day. It has an overall length of T48ft., and is designed for a top speed at sea level of 307 m.p.h., and for an aver- age cruising speed at 15,000ft. of 269 m.p.h. Its range will naturally vary with the number of passengers carried, and a number of alternatives have been worked out. With a range of 2,500 miles the Blackburn boat would carry 160 passengers and 30,400 lb. of freight and mail, or 85 pas- sengers and 57,700 1b. of freight and mail, both figures being based on daytime seating accommodation. Equivalent figures for a range of 4,375 miles are 72 passengers and 2,980 lb. freight allowing for sleeper accommodation, or 85 passengers and 3,450 lb. freight, allowing for daytime seating. Pressure Cabin In view of the operational altitude of 15,000ft., all crew, passenger and freight spaces are pressurised to give atmo- spheric conditions equivalent to an altitude of 8,000ft. only. To achieve this, the hull is built in the form of a body of approximately circular cross-section extending the full length, and the planing surfaces are built on to this body. The main body is pressurised from the bow to aft of the galley, which is to the rear of the passenger or freight compartments. The space between the main body and the planing bottom is at atmospheric pressure. This space is watertight and is subdivided into compartments of such size that in the event of damage the flood- ing of any two adjacent compartments would not sink the aircraft. ' The tailplane is given considerable dihedral, which in- creases the clearance from the water thrown up during take- off. Wing-tip floats are fitted and these may be either fixed or retractable. The aircraft is of all-metal construc- tion. Aluminium alloy is used in the main for framing and skin plating, and steel for highly stressed parts. Thermal provided. de-icing is provided for the airscrews and the leading-edges of all flying surfaces. All fuel is carried in the win"gs. A wide variety of internal arrange- ments is possible depending on the service. In one suggested arrangement, which pro- vides for 85 passengers, two decks On the upper deck, forward, is located iloperational cabin, providing for pilot, co-pilot, navigator, General Particulars Maximum gross weight ... 310,000 1b.Overall length 148 ft. Overall span 202 ft.Wing area 5,000 sq. fl. Performance (Based on Gross Weight) Top speed at sea level ' 307 m.p.h.Absolute ceiling 20,000 ft. Initial rate of climb 940 ft/minute.Cruising altitude 15,000 ft. Cruising Performance (1) Still air range 2,500 miles. Mean cruising speed ... ... ... 269m.p.h. Payload 85 passengers + 57,7X0 lb. freight and mail (based on daytime seating accom-modation). 120 passengers 4- 44,960 lb. freight and mail.160 passengers -f 30,480 1b. freight and mail. All freight 90,960 lb. Cruising Performance (2) Still air range 4,375 miles. Mean cruising speed ... 280 m.p.h. Payload 85 passengers (day seating) 4- 3,450 lb. freight. •45 passengers (sleeper) 4- 15,125 Ib. freight. 72 passengers (sleeper) + 2,980 lb. freight. •The above payloads are based on a passenger weight of 180 lb. plus 55 lb. baggage per passenger. radio operator and engineer. To the rear of the operational^ cabin is the crew's rest room. Apart from the galley aJP*V the rear, the remainder of the upper deck is given over to freight space. On the lower deck the forward compartment houses the winches and other marine equipment, and the auxiliary electric generating plant, etc. The forward passenger saloon comes next and is divided in two by a screen bulkhead. The forward portion has seating for 29 pas- sengers and the after portion seating for 24 passengers. A central passage flanked by toilet and dressing rooms joins the forward and aft passenger saloons. The latter has seating for 32 passengers, and to the rear of this com- partment is the entrance,hall, and aft of this a compart- ment for passengers' baggage. One aspect which is often lost sight of is that the develop- ment of a large flying boat will probably cost less than that of a corresponding landplane. The wings are the same for both'. The hull can be a scaled-up version of smaller, W! well-tried hulls and thus should not introduce any experi- mental features. The undercarriage for a large landplane, on the other hand, presents problems which cannot be said to have yet been solved.
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