FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1960
1960 - 0906.PDF
16 FLIGHT, 1 July 1960 Inside the 11-18 . . . The neat flight-deck, the arrangement of which is described below, is finished in grey, with black panels and dials control propeller pitch. It also providespower for nosewheel steering and for the windscreen wipers. Total fluid capacity ofthe system is 16.5 Imp gal, with a reservoir capacity of 10.5 Imp gal, filling being eitherby gravity through a filler cap on the reservoir or by pressure through connec-tions in the nacelles, using a ground hydraulic power unit. A maximum work-ing pressure of 2,9851b/sq in is maintained in the system by two engine-driven pumpscapable of handling 8.8 Imp gal per minute. Linked with the hydraulics is a com-pressed nitrogen system which is used not only to charge the hydraulic accumulatorsbut to provide emergency braking and propeller feathering. The gas iscontained in two bottles, one of 0.42 cu ft capacity for the brakes and the other of 0.10 cu ft capacity for the emergencyfeathering. Storage pressures are l,850-2,135Ib/sq in and 8501b/ sq in respectively; and the bottles and hydraulic accumulators arecharged simultaneously from a ground unit. The 11-18 has both d.c. and a.c. electrics. The d.c. supply isfrom eight engine-driven generators (rated at 12kW) and from batteries, the rated voltage being 28.5 with the generators and24 with the batteries. The single-phase a.c. current is supplied by four 8kW alternators and an inverter. Three-phase a.c. supply isfrom two more inverters, of which one is for emergency use. The complete electrical system is of the ring multi-wire type,with the bus-bars arranged in a four-wire two-way system which will remain operative so long as any one source of power keepsfunctioning. On the ground, a.c. and d.c. current are supplied from a g.p.u. through external international standard sockets. Availability of these powerful and reliable electric power sourceshas enabled the Il-18's designers to utilize an electric thermal de-icing system capable of coping with severe icing conditionswith one or even two engines out. This is in line with the view expressed by Soviet delegates at the recent Napier ice-protectionconference at Luton—that hot-air wing de-icing is preferable for turbojet aircraft, but that an electro-thermal system is better forturboprop transports, where hot-air bleed from the engines might lead to an excessive reduction in power. The de-icers on the wing, tailplane and fin leading-edges havean insulated sandwich structure consisting of two metal skins with a heating element between. The wire-grid elements on eachhalf-wing and tail surface are made in four separate sections which take their power in turn from the d.c. system. Ten per cent of the wing chord is protected by de-icers, and7-8 per cent of the tail-unit chord. Heat loading over the aerofoil varies from 6.5 to 9W/sq in. The switched-on period of eachsection is 30sec and the ratio of switch-on to switch-off time is 1:4. A similar system is used for the propeller blades andspinners, except that in this case the power comes from the a.c. source. The blade-heating elements cover 60 per cent of thepropeller radius and 17 per cent of the blade chord. Heat loading is constant along the chord and variable along the radius, from9.7 to 12.9W/sq in. The switching cycle is 24sec on and 24sec off. Also heated by a.c. current are the laminated windscreen panels,which have a transparent electroconductive film between two layers of silicate glass. In this case the heat loading is 3.9W/sq in.Finally, the engine air intakes and generators are heated by hot air tapped from the last stage of the compressor.Safety Features From what has been written so far it will be obvious that the 11-18 design team have placed great emphasis onstructural and operational safety. Sufficient power is available for easy take-off on any three engines and for maintenance of heightin cruising flight on two. Landing and take-off runway require- ments and undercarriage design are such that emergency landingscould be made at small unpaved airfields. A feature of particular interest is that the flight deck is separatedfrom the main cabin by a pressure bulkhead, so that a sudden decompression of one would cause no loss of pressure in the other.Another safeguard is that much of the key navigation, radio and pressurization equipment is duplicated. The fire-extinguishing system consists of six built-in extin-guishers of 10.5 Imp gal total capacity to deal with fires in the engine nacelles, plus five portable CO2 extinguishers of 2.5 Imp gal total capacity to combat fires in the flight deck or passengercabins. The system is so arranged that three of the built-in bottles are discharged automatically at a signal from the fire-warning devices, while the other three are under the control of the . crew. Mechanical levers on the underside of the inboard nacellesare tripped to operate the system in a wheels-up landing. Accommodation The total pressurized volume of the Il-18's ,fuselage is 8,475 cu ft, of which the flight deck accounts for 330 cu ft, the forward under-floor cargo hold 470 cu ft and the rearunder-floor hold 483 cu ft. In addition, there is an unpressurized baggage compartment of 250 cu ft capacity to the rear of the maincabin, with a large external loading door. There are two passenger entry doors, one fore and one aft of 'the wing on the port side, each measuring 4ft 7in high by 2ft 6in wide. The four emergency exits are 2ft 6in high by lft 6in wide. . A flight crew of four is standard, with the navigator's stationfacing sideways on the port side, behind the captain, and the radio operator's station facing sideways on the starboard side, behindthe co-pilot. Provision is made for a removable seat for a flight engineer between the navigator and radio operator. Layout of equipment and instruments is neat and unsophisti-cated. Each pilot has a blind-flying panel and comprehensive flight instruments, including a weather-radar scope and ILSindicator. Radio and electric controls are above the central panel, which carries the powerplant, hydraulic system and pressurizationsystem instruments. Radio-compass controls, fire-extinguishing •••' buttons and the switches for some other systems are on the roofpanels. Outboard of the captain's position is a long console carrying fuel jand oil gauges, engine starting controls and some radio controls. " A similar console on the starboard side carries the instruments 1and controls for the air-conditioning system and warning lights. Controls for the engines, undercarriage, flaps, trim-tabs andelectric autopilot are mounted in the normal way on the pedestal between the pilots' seats. At the navigator's station are a charttable, control panel and vertical instrument panel carrying, among other items, ADF indicators, course indicator, automatic naviga-tion equipment and a radar scope. Few details are available of the types of radio and radar fitted,but they include standard communications equipment, two auto- matic radio-compasses, a radio altimeter, ILS, marker beaconreceiver, intercom and the nose radar. This last offers all the versatility of its Western counterparts, with provision for stormand terrain warning, ground mapping and for picking up ground beacons as a navigation aid. Unspecified long-rangenavigation equipment is offered on versions of the 11-18 intended for service on international routes. Turning now to the passenger accommodation, the customer istold that "the 11-18 can be delivered with any technically feasible ' layout of interior compartments, trimming and equipment." Themost popular model is the I1-18B, which seats from 73 to 111 passengers in three separate cabins. The forward cabin in thisversion takes from 20 to 24 passengers; the main cabin 71 coach or 50 first-class passengers; and the rear cabin 14-16 tourists oreight passengers on luxury-class "slumberettes." Headroom throughout is 6ft 6in and maximum cabin width 10ft 7in. All seats are mounted on rails to permit quick adjustment ofpitch, and it takes from one to two hours to convert the cabins from one class to another, using six-abreast seating for coachclass, five-abreast for tourist class and four-abreast for first-class.
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
