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Aviation History
1948
1948 - 0078.PDF
FLIGHT S R/45 . . . of the planing bottom topsides and the lower half-babble are joined at the deck-level '' waist" by a Y-section extru- sion, the stem of which is through-riveted with the deck plating. As the lower-deck stringers are intercostal to the hull frames, the webs of the latter are pierced only by iin x Jin slots for passage of the butt-straps which unite the stringer free-flanges; stringer webs are attached with large shear cleats on one side and small angle clips on the other. In opposite fashion to this, the upper-deck frames are pressed channel-members notched for passage of the stringers, the latter being, as in the lower deck, rolled Z- section members. At the upper deck " waist " the frames are united by doubling plates whilst the skin plating of the upper and lower halt-bubbles meet at and are joined by a similar Y-extrusion to that used at the lower waist. Although in the planing bottom all linear members are extrusions, these are remarkable chiefly for their rarity in the hull structure above. Stringers are rolled members and, forward of frame 13 and aft of frame 32 (the frame pitch is 28m) the frame '' booms'' are heavy-gauge press- ings. Between these stations, that is to say in the middle body of the hull from the wing leading- edge ait, the maximum amplitudes of bending moment occur, and the frame booms are extru- sions ; to complement this the stringers in this region are 16-gauge whereas in the fore- and after- body of the hull they are 18-gauge. Power Installation Little can be said at this juncture about the wing and power-installation aspects of the SR / 45. The aerofoil section to be used is of a t/c ratio appro- priate to a cruising speed of 350 m.p.h., which we calculate to be of the order of 17 per cent at the root tapering to something over 11 per cent at the tip; the section ordinates have been calculated by Saunders-Roe themselves. The intention is that the wing shall comprise a centre-section of 27ft span carrying inner-wing panels extending 40ft 3m to connect up with the outer-wing panels which project a further 56ft; thus the overall span totals 219ft 6in. Power is to be provided by ten Bristol Proteus airscrew-turbines mounted in four coupled pairs, with two single outboard units. The power instal- lation is particularly interesting in that each pair of coupled Proteus will jointly power a two-stage reduction gear, the final stage of which will drive a contra-rotating airscrew; the outboard Proteus will each drive a single blade-bank airscrew. This drive scheme will presumably incorporate clutches whereby a defective engine could be uncoupled in order to relieve its fellow of the burden of driving it. Looking forward and down on to the top deck of No. I (the most advanced) hull a fine sense of shape and size is imparted. January 15th, 1948 Details of " waists " in hull between (left) upper and lower decks and (right) lower deck and planing bottom. Here are shown the differences in upper and lower frames, the frame anchorages, and use of the Y-section longitudinal butt-strap^ The proposed operating pro- cedure is to use full engine power for take-off, and then immediately to throttle back to 97^ per cent power for steep-angle climb up to about 30,000ft, this taking approximately three-quarters of an hour. (Since the Proteus is said to have an e.s.h.p. of about 3,500, the L/D for take-off can be reckoned as approximating to 10.8, whilst for climb at the quoted percentage power the L/D increases to about 11.1—values which promise an ample power safety factor and argue a pretty brisk per-1 formance.) At 30,000ft the aircraft is put into a low-angle ^ continuous climb, maintaining 97^ per cent power, until an altitude of 40,000ft is reached after about 12J hours. The outer single units are then throttled back to the idling condition and half of each coupled unit is also throttled -back. The aircraft then " power-glides " down to sea-level, taking about fifty minutes for this operation. Presumably, after having achieved an altitude of 30,000ft, the aircraft would be levelled-out and-, to all intents and purposes, the major portion of the flight would be made "straight and level." The fact that the aircraft gradually climbs another 10,000ft during the ensuing n-f hours is, we imagine, due to the changing L/D resulting from fuel consumption; it is patent that no human pilot could hope to hold an aircraft in a progressive rate of climb of 15 ft/minute. Additionally, there are grounds for com- ment in the fact that the cruising power should be so high a percentage of the maximum as 97^. The turbine's char- acteristics in this matter are well known, but we should have thought a percentage power of between 70 and 80 would be rather more appropriate.
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