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Aviation History
1946
1946 - 1425.PDF
JULY 25TH, 1946 FLIGHT The de Havilland Sea Hornet is an excellent example of horizontal- hinge wing folding practice is the most modern manner. load case, with the result that large electric motors, batteries and cables are required: in addition, the current delivered by the engine-driven generator is of no assis- tance when considering the total wattage required. For these reasons hydraulic power has been used exclu- sively for all wing-folding services on all British and American aircraft. First in the field in this country, and probably anywhere in the world, were the Lockheed Hydraulic Brake Company, of Leamington Spa, who as early as 1938 fitted a system to the Fairey Fulmar for the operation of its folding trailing edges. This was followed by an improved high-pressure system in the Barracuda— again for the trailing edges—whilst of to-day's naval air- craft, Lockheed hydraulic systems are being used both in the Spearfish and the Sea Hornet. There are a number of features in the equipment of these latter two types which are of interest from the point of view of powered wing folding. The jacks are designed with a damping device incorporated at each end in order that rapid movement of the wing is possible without excessive inertia loads at the end of the travel. The move- ment is gradually slowed by a special valve which comes into operation during the last half to three-quarter inches of the jack travel. This damping is obtained by restricting thedisplaced fluid at the jack connection. The valve is so constructed that the dynamic fluidis controlled to maintain a pressure progres- sively increasing over the travel of the valve,so giving the most desirable form of retarda- tion. The maximum jack load in the horizontalhinge type can vary between very wide limits ; on one example, for instance, the load com-plete with bomb is three times that of the bare wing. This results in wide variations in actuat-ing speed which cannot adequately be dealt with by an ordinary restrictor valve of thefixed orifice type and, if this is arranged to provide a safe speed in the loaded conditionthe movement will be too slow when unloaded. To cater for this condition, by providing aconstant speed of jack operation irrespective of load or pressure, the Lockheed constant flowvalve was designed. It is fitted in the junc- tion of the wing-lifting jacks in place ofthe T-piece between the jack lines and the selectpr-valve, and is effective in controlling flow with+ 10 per cent at pressure differentials of 1,000 lb sq in. A further feature of Lockheed systems which is par-ticularly valuable is the hydraulic power accumulator. If it is decided that the operational requirements are suchthat high engine speeds are permissible when spreading and folding, and if the resulting slip-stream does not makespreading head to wind the overriding case, a compara- tively small accumulator can be used. If, however, fullspeed folding or spreading with the engine off are con- sidered necessary, the large accumulator capacity necessi-tated can be made to do useful work in the flight case. There are a number of ways of arranging this. Probablyone of the best is to divide the capacity into two accumu- lator chambers one of which is connected to the servicesin the normal way, whilst the other is piped with a simple on /off lock to the emergency lines to act as an emergencyaccumulator. The advantages are that instantaneous operation of dive brakes in half to three quarters of asecond is possible, and the requirements for a chassis operating time of less than five seconds can easily be met,using one small pump. An additional advantage of the accumulator emergency system is that the speed of opera-tion in the emergency case is as high as the normal. FROM THE FLYING CLUBS IN addition to the clubs listed in our recent table, we learnthat the Lochleven Aero Club have now started operations hom Kinross airfield. Yet another club for the benefit of prospective members inthe London area is expected to start operations within the coming two months. This is the Middlesex Flying Club, andits base will be at Denham. At present, the facilities there are somewhat limited, but accommodation will be provided assoon as building arrangements are a little less restricted. The Cotsvvold Aero Club, of Coombe Hill, near Cheltenham,is hoping to be able to start flying within the next two €ths. An Auster is expected before the end of this month,the provisional rates have been arranged at £3 an hour forand /2 10s for solo flying. So far, however, the airfield situation is uncertain. Although the Edinburgh Flying Club has not yet been ableto obtain possession of its pre-war headquarters at Macmerry, the Club hopes to resume operations some time in August.During this month three Austers will be obtained, and the dual and solo flying rates have been settled at £3 an hoarThe temporary address of the "interim secretary" is 50, Melville Street, Edinburgh. The Herts and Essex club is rapidly getting back to its pre-war strength. Something like a hundred and fifty flying njAflr-'** bers have now been enrolled, and during a recent forfnighteight members renewed their "A" licences, including severalj* who were members of the club in pre-war years. The cluF^house at Broxbourne is now very nearly back to normal, with seven bedrooms available for residents. The Hampshire Aeroplane Club will be re-starting operationson August 3rd from their pre-war base at Southampton Air- port, Eastleigh. The rates for dual and solo flying have beenprovisiojjally fixed at £3 15s per hour on Tiger Moths. The Club's telephone number is Eastleigh 87237. If everything goes according to plan, two pre-war clubs inthe Leicester area—the Leicestershire Aero Ctub and the County Flying Club—are to be amalgamated. The newly con-stituted organization will be known as'the Leicestershire Aero Club- On August 13th there will be a meeting at the OrientalCafe, 14, Market Place, Leicester, so that the suggestion can be put into practice. There was a combined flying meeting atRearsby last Sunday which was organized by the Leicester- shire, County and Auster Clubs. Some time ago we gave brief details of the plans of theGloucester Flying Club, which has been formed with the object of providing inexpensive flying. Although the club is stillwaiting for aircraft, ground instruction has now started at their centre at Staverton airfield, on the Cheltenham-Gloucesterroad. Staverton will also be used when the expected aircraft arrive, and it is anticipated that the charge for instructionalflying will be in the region of 15s an hour. Details can be obtained from the secretary at 12, Arthur Street, Gloucester. Recently the club hired from Continental Air Services anAusteT IV, and this aircraft was used to give members some preliminary air experience. Each flight was of fifteen minutes'duration, and between 10 a.m. and 7.30 p.m. Sqn. Ldr. Ar- buthnot made some seventy trips. The club now has morethan a hundred members.
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