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Aviation History
1956
1956 - 0913.PDF
FLIGHT, 6 July 1956 59 Airliners of the World E R A L HANDLE? PAGE, LTD., CRf CK LE WOOD. LONDON IN the early years of the present decade Handley Page con-ducted an intensive survey of local-service and short-hauloperators in all parts of the world in an earnest endeavour to formulate some sort of conclusions regarding the type of aircraftnecessary to replace their fast-wearing-out equipment. It is exceedingly difficult to carry such a task to completion in the faceof such variables as: low- or high-mounted wing; piston engines or turboprops; and two engines or four. Gradually, however,the H.P.R.3 project took shape and in 1952 detailed design began along the lines which are now familiar.As befits a company with the traditions and integrity of Handley Page, very extensive testing and development paralleled the construction ofthe prototype, although the latter task took only 15 months. New tech- niques, including advanced spot-welding and sandwich construction, areembodied in the airframe. These have been extensively proved in the company's military work. The Herald has now emerged as an aircraftcarefully engineered to meet the general needs of a large number of operators in virtually every country.AIRFRAME. The wing consists of a centre section, two outer panels, and the tips. The form of the structure is clearly shown in thecut-away drawing, which reveals such curious features as the corrugated- sandwich web and upper and lower booms in the spar, which extendsonly across the centre section. Over this portion of the wing the skin also is a metal sandwich formed from a corrugated filler spot-welded toinner and outer skins. The outer panels revert to a more conventional form of construction. One of the advantages of the sandwich skins inthe centre section is that ribs are required only at the attachment points of the undercarriage, nacelle, outer panels and fuselage. The fuselage has a section formed from various circular arcs, the twoprincipal radii intersecting on two chine beams running longitudinally at the sides of the wide floor. The multiple frames are Z-sections abovethe floor and pressings below; to them are pop-riveted the top-hat stringers to which the skin panels are spot-welded. The fuselage ispressurized and the main frames aligned with the front and rear wing webs are box-sections stressed to withstand belly-landing loads. Themain doors are to port with emergency exits on the opposite side. Regarding the tail construction, little needs to be added to supple-ment the drawing. The use of fluted skin makes possible a very simple internal structure and it has been widely employed. The undercarriageis a product of Electro-Hydraulics and comprises single shock-struts carrying twin wheels, each unit retracting forwards hydraulically into abay sealed by twin dcors, closed by mechanical links to the leg. The main units are each hinged from a forging attached to the rear web andaid hoc ribs in the centre-plane, and the wheels, tyres (inflated to the low pressure of 50 lb/sq in) and hydraulic disc brakes are suppliedby Goodyear. The nosewhcels can be steered hydraulieally by a wheel on the control column through +55 deg.Flying controls are all manual. The elevators and rudder each carry a sloping horn balance and are aerodynamically balanced by gearedtabs and mass balances along the leading-edge beaks. Geared tabs are fitted, of which one on each surface can be used for trimming. Theailerons are similar in the use of tabs and internal balance but horn balances are not fitted. A single large Fowler-type flap is fitted on eachwing, running in four guide rails and lowered by hydraulic rarris, cables and chains. POWERPLANT. The standard engine is the Alvis Leonides Major14-cylinder, two-row, piston engine rated for take-off at 850 h.p. It is expected that, when the Herald becomes ready for service next year,the overhaul period will be at least 400 hr, and probably 600 hr. The airscrews are by de Havilland Propellers with three blades fittedfor feathering and optional reversing, the diameter being lift. Petal- type cowlings, as shown in the drawing, provide excellent accessibility.Intakes for the oil cooler and engine air are integral with the upper and lower petals; the exhaust is discharged on the outboard side of eachnacelle and accessories are mounted behind the firewalls. SYSTEMS. Air Conditioning. The design pressure differential is3.35 Ib/sq in. Ram air enters through an intake in the leading edge between each pair of engines and passes through Vokes filters to twoGodfrey blowers, one of which is driven by each outboard engine. The air is then passed through heat exchangers in the nacelles, where it iscooled by ram air, and is then ducted behind the main wing box to the ceiling panels of the passenger cabin which it enters at foot level andthrough individual louvres. The air is extracted between the interior trim and fuselage skin and leaves beneath the floor. In a fully furnishedand part-insulated Herald, the cabin temperature can be stabilized at 18 ±3 deg C above 10,000ft with an o.a.t. from -30 deg C to inter-continental maximum. Fuel. The system has been designed to satisfy both the A.R.B. andC.A.A. There are four flexible tanks which each hold 175 gal between the inner and outer engines and on each side of the fuselage, giving atotal of 700 gal. At the root of each outer panel an auxiliary 75-gal tank can be fitted. Hydraulics. Pumps are mounted on the port inner and starboardouter engines, energizing the system to 3,000 lb/sq in. Hydraulically operated services include the undercarriage, flaps, nosewheel-steeringand brakes. Emergency services are provided by air bottles connected by independent piping. Electrics. Each inner engine drives a 6 kW D.C. generator regulatedat 28.5V to give a normal rating of 200 amps. These bear the main generating loads at engine speeds above 2,000 r.p.m. Each outer enginedrives a 7.5 kVA alternator; the port unit supplies power for ice protec- tion and the starboard alternator acts as a stand-by, and, through atransformer/rectifier unit, provides the D.C. current for taxying, ground- idling and emergency services. Two inverters in the nosewheel bayprovide 115-V current at 400 c.p.s. for instruments and radio. The system is currei»:ty being somewhat altered. De-icing. In each outboard nacelle is a heat exchanger in whichfresh ram air is heated by exhaust gas and ducted along the leading edge of the wing and, between the ceiling trim and top of the fuselage, to thetail unit where the duct divides into three to feed the tailplane and fin. At each leading edge the skin is stiffened by a spot-welded inner skinwith corrugations which leave chordwise passages approximately 0.1 in deep for the hot air. If icing is not expected to be severe mechanicalovershoes can be fitted as an alternative. The airscrews can be elec- trically de-iced and the pilot's windscreen may have either an electricor fluid system. FLIGHT EQUIPMENT. In most normal operations the Heraldwill have a crew of two, although a station for a radio officer can be provided. For ferrying purposes the aircraft can quite easily be flownsolo. Radio controls are in the roof and further services are controlled from consoles at the sides of the cockpit, that to port embodying the
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