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Aviation History
1950
1950 - 2147.PDF
560 FLIGHT, 14 December 1950 PILOTING A FREE BALLOON ... rip-cord can be pulled at tree-top level. Passengers must hold on tightly, and bend their knees, and on no account must they leave the basket until ordered to do so. In calm weather the balloon is valved down. The trail rope and bumping bag play an important part in all land- ings: they act as automatic ballast, and slow down the drag. In these days of overhead cables, neither should be lowered until it is quite certain there is no danger from this source. Once on the ground they relieve the balloon of much weight, and slow down its descent until it starts to rise. Then more weight is automatically lifted and the balloon again sinks earthwards. The bumping bag replaces the grapnel. It is made up of wrappers and odds and ends which are put into a small net on a line of about 100ft in length. In light winds the usual crowd of people who always seem to collect can pull the balloon to earth by the trail rope. This is known as a "trail-rope landing" and,makes a second ascent possible, though perhaps with one occupant less in the basket. In good weather the balloon may be pegged down under cover for the night Then, after the sun has expanded the gas, and so increased the lift, some of the original load of ballast can be replaced, and the " balloon goes up." To return to windy weather: Mr. Brewer's formula was to "descend with as much weight but as little speed as possible." Hence the importance of ballasting-up at a low height. There is then no time to gain much downward momentum, and the valve can be opened fully when nearing the ground. Instruments consist of an altimeter; statoscope or, better still, a rate-of-rise-and-fall indicator; and a thermometer. A quantity of tissue paper, as has been said, is also very useful. The instruments should be mounted in a small wicker- work basket made fast to the car lines A gas thermometer can be most interesting and useful, but has seldom been used in a free balloon. Airships often carry one, for the larger the ship the greater will be the effects of superheat and the like. A recording barograph is most valuable, for it shows the pilot, by the straightness or otherwise of its line, how suc- cessful his piloting is. The barograph, and a detailed log showing details of ballasting and valving, are of much value after the flight. Binoculars and a compass must also be carried. A garden trowel is used to shovel out ballast, and a knife to cut away the trail rope in case of necessity. As to maps, their scale depends on the proposed length of flight. The map is carried on a large board rigged outwards from the basket, so that it takes up no room. A free balloon turns slowly on its vertical axis, and this makes map-reading more difficult. A limited amount of free ballooning took place in this country between the two wars. Here an R.A.F. balloon, piloted by VV/C. R. S. Booth of airship fame, is seen leaving Cardington in 1933. The well-known French pilot Charles Dollfus has made several ascents in this country during the past two years and in 1948 a short unofficial flying course was held at Cardington, his 10,000 cu ft balloon being used for the purpose: six ascents were made in three days. Ideally, if facilities could be made available, all enthu- siasts who wish to join the Airship Club and fly the Bourne- mouth would greatly benefit by obtaining some free-balloon experience beforehand. Free ballooning is a very fine sport. There is no pleasanter way of taking to the air. The earth appears to drop away at the start and the balloon seems to remain motionless throughout the flight. There is no wind, and, except for the creak of the basket and ground noises, com- plete silence. To be alone in a small balloon in complete silence, above the clouds and out of sight of land, is a wonderful experience. Piloting is interesting, and every flight is different. As the final landing place is unknown, every free run is a mild adventure. In windy weather the landing can be really exciting. In light winds, the final touch-down is so gentle that the pilot and passengers hardly know the exact moment that they are on the ground. THE VANISHING AERIAL DURING the war, radio and radar installations in aircraftsteadily increased in number and complexity and, as time went on, the sprouting of more and more aerials in a variety offorms became accepted without comment. But protuberances exact a penalty in the shape of drag, and as drag varies more orless as the square of the speed, the importance of reducing the drag associated with the aerial arrays rapidly became empha-sized—the more so with the advent of the turbojet, by means of which considerably higher flight speeds were made possible. The problem facing the aircraft designers and radio engineerswas how to provide aerials, either internally or as an integral part of the aircraft structure which would have the same charac-teristics and radiation properties as external aerials and be equally efficient. These matters had been under consideration in theMarconi research establishments for some time, when, in November, 1946, the company collaborated with de Havillandsin order to evolve a system of " suppressed" aerials for the Comet. A Lancaster fuselage was procured, and practical experimentswere made with it. together with scale-model aircraft, at the Marconi laboratories and works at Writtle. From these experi-ments it was finally concluded that there were three practical arrangements for H.F. communication, M.F. receiver and I.L.S.aerials; two for V.H.F.; and one each for Rebecca and A.D.F. All these were carefully explored until the best in each groupwas found. For the final development stage, a full-sized air- craft was used, and ground tests were made at de Havillands atHatfield. The first Comet had no suppressed aerial during the initialflight tests, but on later flights overseas, a long-range H.F. com- munications suppressed aerial was fined, together with sup-pressed loops for the A.D.F. The second Comet has (and, of course, all subsequent Comets will have) a totally suppressedaerial system. The main fin, which is insulated from the stub fin,-is used asan H.F. aerial. In dielectric tips fitted on the fin and tailplane are aerials for V.H.F., O.R.B. and IX.S. In the case of M.F.,a grid aerial is mounted behind dielectric flush panels in the nosewheel doors. Loop and sense aerials for A.D.F. are mountedin the top fuselage and are covered with dielectric flush panels. The I.L.S. glide-path aerial is mounted in the cockpit behindthe windscreen, whilst the remaining I.L.S. aerials, D.M.E. and radio altometer aerials, are mounted behind dielectric panels inthe underside of the wing-root fillet.
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