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Aviation History
1973
1973 - 0047.PDF
FLIGHT International, 4 January 1973 37 Turbomeca Astazou (France) Single-shaft turboshaft and turboprop. This engine and its military and civil applications are described in the civil section. Turbomeca Turmo (France) Free-turbine turboshaft. Details of this engine and its military and civil applications are given in the civil section. Turbomeca Artouste (France) Single-shaft turboshaft. Details of this engine and its military and civil applications are given in the civil section. United Aircraft of Canada T400 (Canada) Free-turbine coupled turboshaft. This 1,800 s.h.p. military version of the PT6T Turbo Twin Pac powers the Bell UH-1N HueyCobra for the USAF, USN and US Marine Corps, the Bell AH-1J SeaCobra for the US Marine Corps and the Bell CUH-1N for the Canadian Armed Forces. Total orders for the T400 (all of which are assembled in the US by United Aircraft of West Virginia Inc) are in excess of 1,000 and development to an eventual 2,400 s.h.p. is envisaged. A Bell Model 309 KingCobra was modified to accept a T400 as part of an evaluation pro gramme by the US Army. Production continues to run at relatively high levels for many of the longer-established engines in this sector, such as the T53, T63, T58, Gnome and the Turbomeca trio. In addition, development programmes are in hand for uprating further the majority of the units. Three new turboshafts are meanwhile at various stages of development—the LTS101 ran in May last year, the T700 is well into its first year of full development, and the BS.360 is starting in" production, while further refinement in development continues. Military/civil V/Stol The main activity in the V/Stol sector is in the military field, where the Rolls-Boyce Pegasus continues to be the prime con tender. Nearly 90 Hawker Siddeley Harriers are in service with the 19,0001b Pegasus 6 Mk 101 and (via a modification programme) the 21,5001b Pegasus 11 Mk 103, there being also an intermediate 20,5001b Pegasus 10 Mk 102. The US Marine Corps also operates Harriers as AV-8As, predominantly using the Mk 103 (all will eventually use this powerplant). With the existing engine and airframe there are also possibilities of exports to other countries, but to provide the opportunity for growth a demonstrator programme was run last year with the 24,5001b Pegasus 15 which on test achieved thrusts of up to 24,9001b. This version embodies a slightly larger fan but is still capable of installation, with minor modifications to the airframe, in the existing Harrier fuse lage. The chances for this engine appear to hang on equip ment decisions by the Royal Navy for through-deck cruisers and the US Navy for its SCS (Sea Control Ship) programme. Also as part of its SCS programme, the USN has contracted for North American Rockwell to build prototypes of a V/Stol shipboard fighter of canard design, with augmentor wing and powered by a Pratt & Whitney F401 turbofan with after burning. The engine is to be modified to provide bleed air for ducting to downwards-operating ejector flaps in each of the four wing surfaces. The resulting augmented airflow provides the necessary thrust for lift-off. This fighter will have a maximum speed of Mach 2-4. The USN is also supporting work on lift-jets for sea-control V/Stol aircraft, which is engaging Detroit Diesel Allison, Garrett AiResearch and Teledyne CAE. For its part, Teledyne CAE has promoted its YLJ95-T-1 lift-jet and has indicated that work being undertaken by the company as part of its ATEGG (Advanced Turbine Engine Gas-Generator) programme is helping to enhance thrust/weight ratios. Figures as high as 40:1 are quoted. Allison has a low-priority programme with R-R on their jointly designed and developed XJ99 lift-jet, which has a thrust in the region of 8,5001b-9,0001b. In Germany, the Defence Ministry last month announced that it was discontinuing financing of the VFW-Fokker VAK 191B V/Stol aircraft as from January 1, a decree which follows the US Navy's decision not to take part in a proposed test programme using the three prototype 191Bs at a cost of $11 million (£4-7 million). On the commercial front, Vtol seems remote as viewed today. There are, however, a number of Stol programmes under way to varying degrees, all of which also have reduced noise as a primary objective. n • • • By HUGH COWIN New Tacan from Marconi THE RECENT SELECTION of Marconi-Elliott Avionic Systems' Tacan for the RAF's MRCAs ends more than 20 years of total US dominance in the design of this airborne equipment. Tacan, together with VOR/DME, is a member of the "rho-theta" family of navigational systems, so called because they provide range and bearing infor mation. Tacan has up to now been purely military—the name is an abbreviation for tactical air naviga tion—and operates in the 1,100MHz band, as opposed to the 115MHz band of VOR, set up to assist commercial operation. Development of Tacan was begun during the early 1950s, much of the original development and production coming from Hoffman Electronics. This company still takes the lion's share of the market, but has now been joined by ITT and its European associates, notably Standard Electrik Lorenz. Significantly, the latter com pany has been chosen to supply its own highly accurate, but more com plex and expensive, form of Tacan for Germany's MRCAs. The AD2770 Tacan represents a new product line for Marconi-Elliott, but is based on a wealth of VOR and DME experience; in fact it contains a sub stantial proportion of circuitry already in service with the AD270 VOR and AD770 DME. The new equipment is designed for applications ranging from trainers to combat and transport aircraft. It con sists of a short 34 ATR transmitter/ receiver, controller and aerial switch ing unit, and employs solid-state design with digital processing in the range, bearing and digital-to-analogue converter circuitry. Extensive use is made of integrated circuits for re liability in military use, and this results in a substantial size and weight saving. Range and bearing information up to 300 miles from the transmitter is displayed on a conventional Tacan indicator. The AD2770 can be operated in one of three ways: (1) transmit/receive, where the system interrogates a selected ground beacon and computes the bearing and slant range to it; (2) receive only, where no interrogate signals are transmitted from the aircraft, but where the equipment computes and displays the bearing of the chosen beacon; (3) air-to-air, where the equipment interrogates other aircraft fitted with a similar system and displays the distance to the nearest. It also replies to interro gation signals from other aircraft. This particular mode is a novel fea ture, and, while no bearing informa tion is available, it does provide a crude homing facility which could be used for station-keeping between a pair of aircraft in poor weather or Nat night. A comprehensive integrity monitor ing system is incorporated, together with; built-in test facilities. The cir cuit;^ provide a clear "no valid infor mation" presentation on the indicator in the event of a failure. Total weight of the system is 351b and the power consumption is 180VA from 115V, 400Hz supply, 50VA from 26V, 400Hz and 10W from the 28V d.c. supply. *
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