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Aviation History
1949
1949 - 1435.PDF
AUGUST ICTTH, 1949 FLIGHT 199 Athena Mark 2 DATA AVRO ATHENA MK 2 ment in accessibility, and therefore in convenience. Cockpit heating is achieved by warm air supplied through a heat-exchanger tapped off the engine coolant system. A pipe taken from the radiator by-passes coolant through the heat-exchanger and so back into the engine system, the cockpit temperature being regulated by varying coolant- flow through the heat-exchanger. This installation, as may be seen from the photographs, is housed beneath the cock- pit floor. A rigid grid-type structure is used for the floor of the cockpit, the side members forming the lower longerons of this part of the fuselage. Wing/ fuselage union is made through forged lug fittings on the longerons, picking up with pin joints to fork fittings bolted on the top booms of the centre-section spars. The essential simplicity of this construction introduced little difficulty when it became necessary to move the wing forward to accommo- date the greater weight of the Merlin; it merely meant that the lug fittings on the longerons had to be shifted forward the requisite amount. • ~'~.-i- ;;i.ti. Fliglrt-control Improvements Transmission linkage in the primary flight control system has been refined, the push-pull tubes having been given straighter runs, so that the number of pivot points has been reduced; this, in turn, has diminished the already very slight amount of backlash which existed in the system. Control-surface tabbing arrangements have also been modified somewhat in that the single spring tab (which could be biased for trimming purposes) on the Mk i rudder has, on the Mk 2, given place to a pair of tabs, the upper of which is a normal trim tab, whilst the lower is a plain spring servo tab. Ailerons are fitted with spring tabs for servo assistance, but have no trimming surfaces, whilst the opposite applies to the elevators, i.e., trim tabs are used without spring servos. The fact that airscrew torque reaction is noticeably greater with the Mk 2 power installation than with the Mk 1 has meant that the original Mk 1 fin area has had to be increased by 5 per cent on the Mk 2, the respective increase in rudder area being- no less than 22 per cent. A slight change of fin and rudder profile is thus noticeable, but the more important result of this modification is that the Athena 2's swing characteristics at take-off and directional trim during climb are claimed by Avros to be better than any fighter employing a single piston engine with uni-directional airscrew. This point will, no doubt, be emphasized when Flight is able to sample the Mk 2 in the air. Some change in dive-brake design has also been made. Whereas the first Athenas had the outboard flaps recessed into that portion of the trailing edge which could be swung Dimensions Span 40ft Length ... ... ... 37ft 6jin Height, tail down ... . ... 12ft lOin Gross wing area '.'.'• • ... 270 sq ft Wheel track • ... ... 12ft 9in Performance Max. speed at 10,000ft 293 m.p.h. Max. cont. cruise at 10.000ft 277 m.p.h. Max. cont. cruise at 15,000ft ... • ... ... 268 m p.h Max. W.M. cruise at 10,000ft 230 m.p.h. Rare of climb at sea level l,830ft/min Rate of climb at 10,000ft ..." l,600ft/min Rate of climb at 15.000ft l,l60ft/min Service ceiling 29.700ft Take-off to unstick ... : ... 300yd Take-off to clear 50ft . 625yd Landing from 50ft to rest • fi90yd Ground run ... ... ... ... ... ... ... ... ",,, .- 3t0yd . Weight Analysis (Normal Dual) '.' ' ' Ib Tare weight - 6,540 Navigation instruments ... ... 3Oxygen ... 35 Miscellaneous .. . .. .. .... ... ... 52 Radio 127 De-icing fluid ... ... ... ... ... ... ... ... ... ... 7 Instructor ... /.. 200 Pupil 200 Fuel ... . 900 Oil • 68 Normal take-off weight 8,132 Desert equipment ... ... ... ... ... ... ... ..." ... 153 Drop tanks 104 Drop tank fuel 648 Overload take-off weight 9,0431b vertically to act as a dive brake, the current system in no way affects flap arrangements, as the braking surfaces are housed in wedge-section recesses formed in the upper and lower wing surfaces clearly forward of the outboard flaps. This is admirably shown in the accompanying photograph. Development work with the Mk i Athenas is still in progress, the first prototype being at Woodford, whilst the second prototype is at the main Chadderton factory. The latter machine is kept company by a Rolls-Royce Dart-powered Mk i which, perhaps, might be referred to as a Mk ij, in that Mk 2 outer wings with the revised dive brakes are employed, together with sundry other refinements which characterize the later versions. This Dart-Athena is also experimentally fitted with an electrical system in place of the pneumatic system with which the Athenas are normally equipped. The first prototype Mk 2 is at present undergoing tropical operation trails at Khartoum, whilst the second prototype is still down at Boscombe. So far, of the pre-production order ot 17 Athena 2s, five are in course of construction, and one is at Woodford being prepared for its initial flight trials. ' : ' .. '. Brabazon I Pressurization THE pressure side of ihe cabin atmosphere control system in -I- the Brabazon I is vested in a pair of Marshall cabin super- chargers mounted vertically on the accessory gear boxes aft of the inboard coupled power plants. These Roots-type positive-displacement blowers each deliver 60 lb air/minute at an altitude of 25,000ft in order to give an equivalent cabin altitude of 8,000ft. All the equipment com- prised in the installation has been tested by Sir George Godfrey and Partners in conjunction with the Ministry of Supply and Bristol Aeroplane Co., the operating trials having included the determination of pulsations within the ducts and the vibration levels and pressure losses throughout the system. The advantages inherent in the essentially simple system ot pressurization employed include the obviation of speed-con- trolling gear boxes. The superchargers are easily removed tor servicing operations and, whilst the simple design makes possible a low initial cost, there is little doubt that the robust construction should afford reliability in service. ' Rig lest pt Sir George Godfrey and Partners of the cabin pres- sure delivery system for the Brabazon I. B 19
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