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Aviation History
1954
1954 - 1205.PDF
FLIGHT, 30 April 1954 537 These perspective sketches show how the Sikorsky HR2S (left) and HSS (right) appear when fully folded for carrier stowage. The HSS might, in addition, be based on other types of ship, for operation from a platform. SIKORSKY TODAY outlook which ignores the possible troubles of a new design until it is in use and then expresses a wish for the original. At any rate, the present "conventional" tailwheel-type undercarriage gives simple retraction, a good run-on and autorotational landing stability. It is noted that the appreciable difference in engine manifold pressure for given fast level-flight speeds with gear up and down indicates the importance of retraction. One interesting point which arises at this juncture is the diffi culty of providing an indication of undercarriage position for the pilot. No fixed-wing method of undercarriage warning applies, because landings are made at full power. The cockpit itself is fairly conventional, and is very broad and roomy. Two pilots are seated side-by-side, as in the S-55. The control of two engines which are, in effect, coupled has posed few problems and should be attainable with a single collective- pitch lever on a single twist-grip throttle. On the other hand, overall power setting and synchronizing may require separate engine controls. In the cockpit are control levers governing hydraulic jacks which open the large double nose-doors, fold the rear fuselage and tail rotor and also fold four of the five rotor blades, one blade being ranged due aft (the folded appearance of the HR2S is shown in a drawing). Micro-switches guard against inadvertent power- folding in flight. Access to the interior of the aircraft is gained via the large nose doors and two other doors on each side of the fuselage. The pilots normally enter by climbing up the outside of the nose, but they can also reach the cockpit from the main cabin by using a folding ladder. The noise level is approximately similar to that of a DC-3 at take off, although the rotor makes less noise than do airscrews absorbing the same power. All fuel is carried in the stub wing, leaving the fuselage usefully free of obstructions and equipment. The normal load is to be two sections of U.S.M.C. assault troops (a total of 26) with equipment, or three small "Mighty Mite" Navy Jeeps, or combinations of other vehicles to a similar total bulk and weight. Provision made for all-weather flying includes extensive de-icing. Civil interest is already considerable. Sikorsky have stated that the basic design could readily be converted into a 35-passenger commercial transport (the S-56) and Mohawk Airlines, of Ithaca, N.Y., have stated that they will eventually replace their DC-3s with helicopters of this size. These operators have already bought an S-55 (due for collection four days ago) for trial services this summer. The price was in the region of £53,500, exclusive of spares. S-58—But for the almost simultaneous release of the later Model 56 (HR2S) this big anti-submarine machine, designated XHSS-1, would have received more publicity. It is generally agreed in the U.S. Navy that the present S-55, or H04S, with either Pratt and Whitney Wasp (600 h.p.) or Wright R-1300 (800 h.p.) cannot do more than a marginal job in the anti-submarine role. Generally speaking, it is either a little low on equipment and stores or short of range. The S-58, which has been ordered as the HSS-1, will do the job very adequately. The engine instal lation and main- rotor drive of the big Sikorksy HR2S, showing the main paths of cooling and engine air. The small trailing-edge flaps are discussed in the text. Bigger than it looks in photographs, the new machine is a blend ing of S-55 shapes with those of the S-56. The power unit, which is mounted at 34 deg. in the nose, is the Lycoming-built Wright R-1820 Cyclone of 1,425 h.p. From the S-55 have come many features born of the immense experience gained on the smaller aircraft, but the basic design is quite new. The rear fuselage, for example, is of the new form, with a large fin. A tailwheel-type fixed undercarriage is fitted, and another item is a small fixed tailplane, apparently devoid of trimmers. The tail rotor has, un usually, four blades. The main rotor also has four blades, which can be folded by hand. The rear fuselage is also hinged, and folds as shown in the sketch above. So far the U.S. Navy are the only Service with firm orders for aircraft of the S-58 family. On the other hand, Sikorsky are convinced there is little future in trying to stretch the S-55, and it is likely that large numbers of the new machine will be built to take over most S-55 work on a bigger scale. S-57—(?) A secret Army project. Sikorsky are reported to have a number of convertiplane studies in various stages of development. , S-59—This type-number has been given to the S-52 four-seat helicopter fitted with a Continental-Turbomeca Artouste turbo prop of up to 400 h.p. We published the performance improve ment achieved by this machine on p. 321 of our issue of March 12th. S-54—Some time ago, Sikorsky made a careful study of twin- rotor configurations, as a result of which it was concluded that— in the present state of the art—there was little to be gained by having two rotors, but that a great deal of trouble and inefficiency might be expected. The loss of power to the Sikorsky tail rotor is small: about seven per cent at full power and half this in cruis ing flight. On the other hand, it was calculated that the overall loss of power in a twin-tandem-rotor helicopter would be about 12 per cent, owing to rotor interference. Sikorsky also consider that the use of two similar handed rotors is not efficient, except from the design and production viewpoint; in fact, different flows call for different rotors. Finally, the American engineers are of the opinion that stub wings on tandem-rotor helicopters are re quired just as much to improve stability as to unload the rotors and increase the possible cruising speed. BROADCAST FROM A VISCOUNT LISTENERS to the B.B.C. Home Service on April 20th were taken aboard that day's Ulster Flyer, the daily Viscount service which leaves London Airport at 7.20 p.m. and is scheduled to arrive at Nutts Corner, Belfast, at 9.5 p.m. On this occasion the aircraft was G-AMOA George Vancouver, commanded by Capt. Caesar-Gordon. It carried a full complement of 47 pas sengers, one of whom was B.B.C. commentator Raymond Baxter, broadcasting via the Viscount's normal Standard Tele phones V.H.F. radio (using an off-airways frequency). Mr. Baxter gave regular reports on the progress of the flight. The quality of reception was such that he might well have been speaking from a studio, only a faint rush of air being audible in the background. The programme opened at 8.1 p.m., with the aircraft over Daventry and nearing the top of its climb to 21,000ft, and concluded 59 minutes later as it entered the circuit at Nutts Corner. April 18th, incidentally, was the first anniversary of the Type 701 Viscount's introduction to scheduled service on the routes of B.E.A. Since then the size of the Viscount fleet has been in creased from five aircraft to 20 and B.E.A. has brought turboprop travel to 27 cities in the United Kingdom, the Continent and the Mediterranean area. The fleet was extremely busy over the Easter holiday period. During nine days the 20 aircraft flew nearly 300,000 miles and carried more than 6,000 passengers. Over the same period there were 167 Viscount departures from the United Kingdom—145 of them from London Airport and 22 from Manchester and Birmingham.
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