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Aviation History
1962
1962 - 2075.PDF
462 FLIGHT International, 13 September 1962 VTOL IN AMERICA A recent model of the VoughtlHiller/Ryan XC-142, five examples of which are under construction Chance Vought Corporation, a division of Ling-Temco-Vought, teamed with Ryan Aeronautical Company and Hiller Aircraft Corporation and submitted the VHR-447 tilt-wing turboprop design which was selected as winner as the XC-142 in September 1961. This team brought together unique technical capabilities and a great deal of knowledge, and it is appropriate to set forth briefly some of the reasoning which governed the proposal. After detailed analysis of various propulsion systems, and con sidering the weight, speed, and flight objectives set forth in the specifications, a tilt-wing design emerged as the most logical solu tion to meet all the specification requirements. The tilt-wing turbo prop also satisfied the other principal points used as a basis of the companies' decision and gave promise of avoiding any element of large technical risk. As a further step in minimizing risk, it was decided to use conventional propellers and a horizontal tail rotor rather than cyclic propellers, because the latter would require the additional development of a cyclic control system. Further, a cyclic system would provide neither the control power nor the development versatility of the tail rotor. Changing the tail-rotor diameter or rotor speed would be much easier to accomplish dur ing development and test than making changes to a cyclic propeller control system. The XC-142 is powered by four 2,850 s.h.p. GE T64 engines driving 15ft 6in propellers being developed by Hamilton Standard. Lightweight gearboxes are provided integrally with the propellers. To permit engine shutdown in flight, overrunning clutches are installed between each engine and propeller. Connecting the integral gearboxes is 8,000 r.p.m. cross-shafting capable of absorbing full power in the event of engine failure or shutdown. Wing flexure is accommodated by flexible couplings in the shafting at bearing locations. The 8ft tail rotor is driven through a fuselage accessory gearbox by an 8,000 r.p.m. take-off from the engine cross-shafting. Span is 67ft 6in, overall length (including tail rotor) 58ft, and height 26ft. The wing has an aspect ratio of 8.6, and can be tilted through an angle of 100° to provide the capability of hovering in a tail wind. It has full-span, double-slotted flaps with the outer sections operated independently as ailerons. On the outboard side of each engine are leading-edge flaps to suppress the wing stall which otherwise would result from upflow of the propeller slipstream during transition to conventional flight. Wing tilt is accomplished by dual synchronized screwjack actuators to provide fail-safe reliability and adequate stiffness of wing support to allow for wing elasticity. The fin carries an all-movable horizontal tail. The landing gear has low-pressure tyres providing a UCI index of 15, permitting operation from grass fields. The fuselage, of semi-monocoque construction, has a rear clamshell door which lowers to form a ramp; there is also a side access door. All primary flight controls are powered by dual hydraulic systems. The unique feature of the control system is a mechanical integrator linkage that transmits cockpit motions to the proper surface as a function of wing tilt angle. The control system functions as follows: Flight condition Conventional Transition Hover Yaw Rudder Rudder, differential collective and ail erons Ailerons in slip stream Pitch Movable tailplane Tail rotor and tail- plane Tail rotor Roll Ailerons Ailerons and differ ential collective Differential collec tive From a performance standpoint, the XC-142 will meet all specification requirements. Cruise speed will be from 200 to 250kt, and top speed more than 350kt. An 8,0001b payload can be trans ported a radius of 200 n.m. with all takeoffs and landings vertical and no refuelling at mission mid-point. With more powerful engines, and small increases in wing span and horizontal-tail area, together with some strengthening of structure for higher gross weights, the aircraft could carry a 12,0001b payload as an STOL clearing a 50ft obstacle in less than 500ft. Hiller has the responsibility for the complete power transmission system, and will fabricate the flaps and ailerons. Ryan will design and fabricate the aft section, to include cargo door and ramp, and the wing panels, to include engine nacelles. Vought will design and fabricate the remainder of the aircraft, and is responsible to the Air Force for overall design and systems integration. At the time of selection last September it was decided that for the five evaluation aircraft the folding features—wing, vertical tail, and tail rotor, to make the aircraft carrier-suitable—would not be included, and the Government management was shifted from the Navy to the Air Force. The basic design is being maintained so that folding could be installed in later aircraft if so desired by the Navy. The full mock-up is due later this year, and the first flight is scheduled for 1964. FORTHCOMING EVENTS Sept 13 Guild of Air Pilots and Air Navigators: Presentation of Trophies, Innholders' Hall, London EC4. Sept. 15 RAF "At Home" Day Sept 15-16 Cranfield Society: Symposium. Sept 16 Tiger Club: Display, Fair Oaks. Sept 16 Wiltshire School of Flying: Thruxton Air Races. Sept 17 RAeS Weybridge: Film Show. Sept 17-23 Grand Prix International de Bourges. Sept 19 RAeS Coventry: "Development of Seaslug," by C. Bayly and A. Lightbody. Sept 19 Kronfeld Club: "More Diving in the Mediter ranean," by Frank Irving and Denis Tomkins. Sept 19-22 Second International Agricultural Aviation Con gress, Crignon, France. Sept 22 Air Display and Races, Shoreham. Sept 22 Elstree Flying Club: Flying display. Sept 25 RAeS London Airport: "Boeing 727," by Jack Steiner. Sept 26 Kronfeld Club: Film Evening: " Victory at Sea" Sept 27 RAeS Halton: "Operations of Special Duties Squadrons," by A. Firth. Sept 27-28 Aerodrome Owners Association: Annual Conference, Blackpool. Sept 28 RAeS Graduates" and Students' Section with Wingfield Lighter-than-Air Society): Film Evening. Oct 2-4 International Symposium on Batteries, Bourne mouth. Oct 7-13 International Rally, Genoa. Oct 9-11 Guild of Air Traffic Control Officers: Convention, Bournemouth.
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