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Aviation History
1931
1931 - 0782.PDF
FLIGHT, JULY 24, li>31 THE ARROW " ACTIVE ": Rear view. Bristol-Frise ailerons are fitted to the upper wings only. are box formation. The whole elevator unit "is readilydetachable. The fin unit is a cantilever built on a main fin posttube, the lower end of which telescopes into a reinforced sleeve which forms part of the rear fuselage stern fitting.The forward fin member is stayed to the fuselage by a triangular arrangement of tubes inside the fairing, andprovides an adjustment whereby the fin unit may be offset in relation to the centre line of the aircraft. Therudder consists of a forward main spar tube and a sub- sidiary spar tube, to which are secured ribs built upfrom drawn duralumin boom sections, all ribs in the tail unit being of this type. The outer framing and trailingedge members are made from streamline section steel tube. The rudder is hinged to the fin tube by machined forkfittings. The lower portion of the rudder is shaped in a particular manner to increase the rudder control duringsuch manoeuvres as spinning. Undercarriage The undercarriage is of the " split " type, the axleshaving machined socket fittings hinged to a machined spool on the bottom longeron or keel tube. The twotelescopic legs are of the oil and spring type, the landing shock being first absorbed by oil discharging through adiaphragm orifice. There are no welded fittings in the undercarriage, and all sockets are machined and of ampleproportions. Grease nipples are provided at all pivot points. The tail skid is a hinged tubular lever, pivoted in amachined forked fitting, which swivels in bronze bushes carried in a housing which forms part of the bottom endof the main stern post. Shock absorption is by a spring working in compression. Controls The flying controls are of normal type, with a duralu-min tube control column and adjustable rudder bar pro- vided with parallel action movement. Direct lines oftie-rod controls are employed throughout, and these are guided by felt pad supports mounted in metal box fittings,the felt pads retaining the lubricant. Engine controls are operated by levers provided withFerodo friction discs, and are interconnected at the quadrant for the return to normal of the altitude adjust-ment. Arens units are employed in the engine controls, and are of relatively large size. Engine Installation As already mentioned, the power plant fitted as stan-dard in the Arrow " Active " is the inverted Cirrus- Hermes type IIB. It is mounted on resilient engine feeton a tubular structure which gives good accessibility to the rear of the engine. The main structural membersare fitted with machined sockets having chamfered barrels to graduate the change of section. Under running con-ditions the structure is particularly free from vibration. The engine mounting may be completely dismantled. Simple gravity feed is employed in the petrol system,a tinned steel tank being mounted in the upper centre- section. A short length of Superflexit pipe line connectswith the carburettor through a quickly-detachable filter on the engine mounting. A dirt trap is provided in thetank sump. An oil system of normal type is fitted, with delivery and scavenge pumps connected by short Super-flexit pipes to a tinned steel tank mounted on resilient pads on the engine bearers. The tank is provided withcooling tubes and air scoops. An oil thermometer and oil-pressure gauge are provided in the system. Cockpit By the particular type of fuselage construction adopted,it has been possible to cut down the sides of the cockpit coaming considerably, so that the pilot may get a parti-cularly unobstructed view. The seat is arranged to take the seat-type parachute, and the seat back is detachable.A very complete set of instruments are provided, and the compass is placed centrally in front of the pilot, abovethe control column. Following is a list of the instruments fitted: Compass,airspeed indicator, inclinometer, altimeter, oil thermo- meter, oil-pressure gauge, and revolution counter. The equipment further includes: Petrol filter, double-pole engine switch, oil filters, safety belt (Air Ministry approved type), and a set of jury struts for folding thewings. Flying Qualities The following extracts from the official Air Ministry report on the flying qualities of the Arrow " Active " may be of interest: — " Aerobatic loading at full weight.—Flight tests withcentre of gravity both in extreme forward and rearward positions. The aircraft was put through all normal aero-batics at this weight and centre of gravity positions, and was excellent to handle. " The controls are light, effective and well harmonisedthroughout the whole speed range. With the centre of gravity in both extremes, two spins to the left and twoto the right were carried out, each of eight turns. The aircraft goes into a spin comfortably and spins smoothlywith nose well down, recovery being easily effected by centralisation of controls. The aircraft recovers levelflight after a small loss of height. All aerobatics can be easily carried out. Turns to right and left in invertedflight are also easily carried out. " At this centre of gravity position a controlled stallglide can be executed if the rudder is used to prevent the aircraft dropping a wing. Control at the stall is good. 728
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