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Aviation History
1963
1963 - 1805.PDF
•& tic Svp.w.-sSf*?' i§lfcp S-6, A 11^° ilC CARGO AND *E§&1 I IT ~\ PERSONNEL <jfetgJSa-- Tc~- N $-61 B ANTI-SUB. SONAR PRESIDENTS S*: FLIGHT S 61 L NON- AMPHI8IOUS S-61N 3$: S-61R Sco/e s/rJe-e/evot/ons of" current members of the S-61 family. Special shading draws attention to major structural differences which are amplified in the text S;IKOR s;KiY„" H E;L i;c o P,T;E RS... engines driving through overrunning clutches to permit single- engine operation. The engines were placed close ahead of the main-rotor gearbox, where the flight crew had been in the S-55 and S-58; and the crew went back to their logical place in the nose. Third major change was that, whereas the upper part of the S-61 hull was modelled on that of the S-58, the lower part was sealed and made amphibious. Altogether the combination of advances introduced in the first Sikorsky turbine helicopters fully justifies the use of the oft-abused term "new-generation." It is appropriate now to describe the SH-3A in order to provide a basis from which to assess the later members of the S-61 family derived from it. 614 FLIGHT International, 10 October 1963 By 1957 it was clear to Sikorsky that the greater power and lighter weight of turbine engines could be combined with an improved design of helicopter to enable a single machine to carry out a complete ASW mission, including both search and attack phases. The Navy called for an endurance of 4hr, carrying a crew of four, full ASW equipment and 8401b weapons, with half the mission consisting of hovering close to the sea, and with a fuel reserve of 10 per cent. The Navy also demanded the ability to operate at night or in bad weather, and to land on the surface of the ocean to effect repairs necessary for the completion of a mission. From the outset the SH-3A was an integrated weapon system of the type long familiar to the US military but never before involving a rotary-wing machine. This required both a revised management structure within Sikorsky Aircraft and an unprecedented pre- flight test programme on all portions of the flying vehicle. By the time the SH-3A entered service with the US Navy in 1961 Sikorsky had manufactured more than 30,000 main-rotor blades each constructed in the manner described in the section on the S-58, by hogging a rough extrusion and then bonding-on a light trailing-edge. These blades had then logged over 7,000,000hr operation. The S-61 blade has a typical symmetrical section (NACA 0012), with a constant chord of 18.25in. Along the outer leading edge of the extruded spar is bonded a stainless-steel abrasion strip. The trailing edge is formed from 23 aluminium "pockets," each rather more than 1ft in length and consisting of ribs, skin and a channel-section bonded to the rebated shelves milled above and below the trailing edge of the extruded spar. These pockets do not affect the blade strength, which is all in the spar. The tip is formed from a separate pressing attached by countersunk screws to the end of the spar. At its inboard end the extruded spar is continued beyond the root trailing-edge pocket and changes in section over a distance of approximately 4ft to terminate in a bolted anchorage to a steel cuff. The latter in turn provides a flat mating face secured against the hub by a row of peripheral bolts, as shown in an inset in the main cutaway drawing of the S-6 IN. The complete blade can be removed by two men using ordinary hand tools. Until the end of the last decade rotor blades were components subject to stringent life limitation, and no inspection method had been found capable of detecting the onset of fatigue in the blade spar (apart from subjecting each blade to a complete investigation by an approved crack-detection method between each flight, which would be an impossible undertaking). Accordingly blades worth $6,000 each would be scrapped, and replaced by new ones, simply because they had reached the allowed life limit. When Sikorsky began to make their spars in the form of a single hollow extrusion it became apparent that minute cracks might be detected by pressurizing the inside of the spar and fitting a pressure-sensitive warning indicator. The idea worked perfectly, and today BIM (blade-inspection method) has been a standard feature of all Sikorsky main-rotor SIKORSKY Maker VS-300A VS-3I6A VS-327 VS-3I6B S-51 S-52 S-55 S-55 S-56 S-58 S-58B S-58 S-59 S-60 S-61 A S-6 IB S-6IL S-6 IN S-6IR S-62 S-62A S-64A S-65A USAF R-4 R-5 R-6 H-5H —. — UH-198 — — — — —. _ CH-3B — —. — CH-3C —, — —. — Designation Navy HNS H02S HOS H03S H05S — UH-I9F — — — SH-34J — • — SH-3A — — — — — — — USMC — — — — — — CH-I9E CH-37C — UH-34D — — _. VH-3A — — — — — — — CH-53A USCG — — — H03S — — HH-I9G — — — — — — — — — — — HH-52A — — — Army — — — — YH-18 UH-I9C UH-I9D CH-37B CH-34A — — XH-39 VH-3A — — — — — CH-54A — Design mission Research Utility Utility Utility Utility Utility Utility Utility Transport Transport Assault ASW Research Crane Utility ASW Airline Airline Cargo Rescue Utility Crane Assault First flight 14.9.39 14.1.42 18.8.43 15.10.43 16.2.46 12.2.47 10.11.49 18.12.53 8.3.54 1.6.54 25.3.59 11.3.59 6.12.60 7.9.62 17.6.63 14.5.58 9.5.62 1964 Powerplant 75 (later 90) h.p. Franklin 200 h.p. Warner R-550-3 450 h.p. P & W R-985-AN-I 245 h.p. Franklin O-440-9 450 h.p. P & W R-985-AN-7 300 h.p. Franklin 0-425-13 600 h.p. P & W R-1340-57 700 h.p. Wright R-l300-3 Two 2.100 h.p. P & W R-2800-50 1,525 h.p.Wright R-1820-84 1,525 h.p.Wright R-1820-84 1,525 h.p.Wright R-1820-84 400 s.h.p. Continental T5I-T-3 Two 2,100 h.p. P & W R-2800-54 Two 1,250 s.h.p. T58-GE-8B Two 1,250 s.h.p. T58-GE-8B Two 1,250 s.h.p. GECT-IIO-I Two 1,250 s.h.p. GE CT-II0-I Two 1,250 s.h.p. T58-GE-8C 1,250 s.h.p. T58-GE-8B 1,250 s.h.p. GE CT-I10-I Two4,050s.h.p.P&W JFTDI2A-I Two 2,850 s.h.p. T64-GE-6 Fuselage length 27-10 35-5 40-10 38-3 -41 — 1* 27-6 42-3 42-3 64-11 46-9 46-9 46-9 30-3 64-3 54-9 54-9 59-1 i 59-4± 60-11 44-7 44-7 70-3 67-2 Dimensions (ft-in) Overall height 12-5 12-9 10-5 12-11 8-8 13-4 13-4 22-3 15-11 15-11 15-11 9-8 21-8 16-10 16-8 16-10 18-10 18-11 16-0 16-0 25-3 24-11 Main rotor diam 28-0 38-0 48-0 38-0 49-0 33-0 53-0 53-0 72-0 56-0 56-0 56-0 35-0 72-0 62-0 62-0 62-0 62-0 62-0 53-0 53-0 72-0 72-0 Tail rotor diarr 7-8 7-8 7-0 8-2 8-9 5-4 8-9 8-9 15-0 9-6 9-6 9-6 6-4 15-0 10-4 10-0 10-4 10-4 10-4 8-9 8-9 16-0 16-0 NOTE: n.a., not applicable; SL, sea level; NRP, normal rated power; TOP, take-off power.
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