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Aviation History
1930
UNTITLED0 - 1299.PDF
FLIGHT, NOVEMBER 7, 1930 the limited space provided in an ordinary aerodrome. One solution hadalready been provided by the Guggenheim Fund—that previously referred to. The " Leader cable " provided another possible solution, but in practice itwas difficult to follow, particularly when it was curved and the air was bumpy. It was probable that the complete solution of the fog landing problem would•depend upon the ordinary wireless receiver for leading the aeroplane over the landing ground and for fixing the moment when the engine should be throttledback, the height being fixed by a barometric altimeter. Much had been said about other methods of measuring height, such as timing echoes, acoustic orradio, or measuring variation in the electrical capacity, but it was safe to say that the barometric method was capable of giving a much higher accuracythan was required for fog landing, provided that the ground barometric reading be communicated to the pilot. Mr. Meredith described some recent experiments which had been carriedout at Farnborough :— "These experiments were intended to investigate the practicability oflanding through a fog of limited height, guided by a balloon moored above the fog. The work included a determination of the magnitude of the errors of thepositioning of the landing and a demonstration with a standard Lynx Avro, by Flight-Lieut. Oddie and Mr. Sudworth, in an actual fog. It was necessaryto develop safe methods of taking off and of flattening out which could be used even if the ground were invisible. " Taking off presented no difficulty whatever with the assistance of thepitch and yaw indicator. It and a simple form of ground proximeter, to be described presently, were the only special instruments carried on the aeroplane.For taking off the tail skid was placed on an inclined ramp and secured by a wire to a bolt which could be withdrawn by a person on the ground after asignal from the pilot. The attitude of the aeroplane on the ramp was chosen to correspond with the attitude on a slight climb. By releasing the gyro-scope in this position, the pilot was provided with a datum in lieu of the horizon, as well as the means of keeping dead straight. " The flattening-out manoeuvre might have been rendered unnecessary hada special undercarriage been designed to absorb the downward momentum of the glide. Such a solution is, however, not likely to recommend itself tonervous passengers, and it was known from previous work that a semi- automatic landing could be achieved by the aid of a ground proximeter. Ithad been shown that an aeroplane approaching the ground at an assigned speed (estimated at about 20 per cent, above the stalling speed), wouldreach the ground flying horizontally at the stalling speed, if full elevator were applied at an assigned height. It remained to determine accuratelythe speed and height for the particular aeroplane we were using. This was done by analysis of accelerometer records taken in the aeroplane while themanceuvre was repeated at a safe height from various gliding speeds near the predicted speed. " The ground proximeter consisted of a weight suspended 13 ft. below thewheels by a length of linen thread attached to a trigger controlling lamp circuits. As long as the weight was suspended, a green lamp showed andwhen the weight hit the ground, the increased tension in the thread switched on two independent red lamps with independent dry batteries and circuits.Two feet on the length of the string was allowed for the pilot's lag in responding to the signal. " About 100 landings have now been made by this method, the necessaryprecision of flying during the approach being attained by the aid of the pitch and yaw indicator. Three different pilots have found that there is nodifficulty in the manceuvre unless there is sufficient wind to produce a marked •wind gradient. To meet this difficulty, which always produces a loss of flyingspeed as the aeroplane approaches the ground (provided, of course, it is landing up wind), it is desirable to add a couple of miles an hour to the speed. Slightexcess speed when the ground signal occurs is easily allowed for easing forward of the control column after it has been pulled hard back andthe only result is an increase in the distance required to come to rest. " To facilitate the transition from level flight to the glide, the pitch andyaw indicator was pivotally mounted and attached to a double-acting pneumatic ram, which was controlled by a tap placed beside the throttlelever. Thus, once the stop on the ram had been correctly adjusted, the pilot was able to rotate the instrument in pitch through the gliding angleas he closed the throttle and by flying to keep the indicator central, he placed the aeroplane at the correct attitude for the glide. Any error in the datum ofthe indicator was apparent on the airspeed indicator and the pilot was able to correct it by flying with the pitch indicator slightly displaced. " To start the glide from the balloon, the pilot proceeded as follows. Theassigned course was set on the compass before leaving the ground. The pilot first ascertained the engine speed required to fly level at the assigned An Air Port for DublinA WELL-KNOWN Irish architect, Mr. A. Delap, in a letteraddressed to the Irish Times recently, suggests that a part of Dublin Bay be enclosed by a wall approximately 2\ milesin length, behind this wall half the space could be reclaimed from the sea for use as an aerodrome, and the other portionused as a flying-boat base. The water, in the section of the Bay which Mr. Delap suggests should be enclosed, is shallow,so no great expense would be incurred in the reclamation scheme. There is, says the writer, no high land to interferewith flight in any direction. Fog, he admits, is the chief difficulty to the scheme, as that prevalent in Dublin Bay isusually low-lying. Ford Airlines Carry 10 Million Pounds of Freight FROM the Dearborn Aeroplane Division of the FordMotor Co., under date of October 23, 1930, comes a Souvenir, per Air Mail, commemorating the 10 millionth pound freightcarried by Ford Airlines in America—Congratulations ! Apropos Ford air transport 'planes—two of which aregiving demonstrations in this country—we understand that 12 of the " 5-AT-C " models have been supplied to SouthernAir Fast Express, Inc. (S.A.F.E.), the subsidiary of American Airways, reference to which was made in last week's issue of PLIGHT. . , Imperial Airways Machine CrashesON Thursday, October 30, a Handley Page W. 10 machine, named the Citv of Washington, which had recently'Jeen re-equipped with two' Rolls Royce '\F " engines, while %ing from Le Bourget for England, crashed in a fog ona hill near Neufchatel. There were three passengers on speed, and, having noted his height when alongside the balloon, he arrangedto fly away from the aerodrome on a course parallel to the assigned course and sufficiently far away to allow for the turn of 180 deg. After flying level onthis course for about a mile and a half, he turned the aeroplane and flew straight towards the balloon until the compass had settled after the turn.He then corrected his course by the compass when close to the balloon and released the gyroscope of the pitch and yaw indicator. He then manoeuvreduntil he was alongside the balloon (moving the throttle if necessary to adjust his height) and simultaneously closed the throttle and moved the tap to alterthe pitch datum. After that, he merely had to keep the pitch and yaw indicator central until he received the signal to pull the control column hardback. " The gliding angle was calculated from the measured rate of descent.After allowing for the wind, the balloon height and compass course were adjusted so that the weight should strike the ground at an assigned positionm the centre of the aerodrome. The wind was measured in some cases by the standard meteorological method, and in other cases it was estimated from theangle of the balloon cable. A table of balloon heights and compass courses was prepared, allowing also for the horizontal displacement of the balloonfrom the winch. Thus, once the wind had been estimated, little time was required for the final adjustments." After fifteen practice landings had been made with the balloon at heights varying from 370 to 420 ft. according to the wind, it was considered safe totake off and land in a low fog, as long as an observer on the top of the balloon shed was clear of the fog ; this precaution was necessary to ensure that theballoon, which was too small to lift a man, was above the fog. On the morning of June 18, 1930, the weather conditions were suitable at sunrise and fivelandings were made through a fog estimated at 90 ft. in depth. The visibility in the fog was variable, but the pilot was not able to observe the ground afterentering the. fog. " The maximum errors of all the landings made from this height were95 yards in range and 50 yards in line. A few tests were made with the balloon at a height of 750 ft. These indicated that the errors were aboutdouble those with the balloon at 400 ft. It would appear, therefore, that on any reasonably large aerodrome, landings could be made by this methodthrough a fog extending up to about 700 ft., provided that the ground person- nel could ascertain that the balloon was in clear air. This could be ensuredby using a man-carrying balloon, or by providing instruments capable of giving the necessary information. May I suggest that the design of suchinstruments would be an interesting and fruitful occupation for persons of an impede flying in this country, and also because the method can be applied withlittle modification with any radio device for fixing the start of the glide instead of the balloon." The risk could be still further reduced if the ground personnel controlled by radio the height of each aeroplane. In any case it was now generallyrecognised that efficient blind flying instruments were an essential part of any aeroplane's equipment. Wireless was no less essential. Thus, the specialequipment required for the densest fog should not amount to more than the sensitive aneroid, the reed indicator (if, for example, the equi-signal beaconsystem be used), and the ground proximeter." It had been suggested that fog flying would never be practicable on accountof the risk of collision. Although there was little prospect of the development of equipment capable of giving adequate warning of the approach of anotheraeroplane in a thick fog, any development which enabled aeroplanes to go up in bad visibility, instead of operating at a common height i.e., the maxi-mum height from which their pilots could view the ground), would materially reduce the risk of collision. It would be advisable to reserve specific heightsfor each line of traffic and thus reduce the risk to that of one aeroplane over- taking another, when the relative speed would be so low as to give the over-taking pilot a reasonable chance. Concluding, Mr. Meredith said, " that air transport in fog is immediatelypracticable, but that it involves an element of risk which will continue until all the equipment required has been proved by many years of actual use.In the meantime the policy should be to press on with the development of the necessary instruments, to equip aeroplanes for landing in fog when they aretravelling such distances that they may be enveloped before reaching a possible landing ground, but to avoid flying in fog whenever possible. Myneglect of the subjects of fog dispersion and of infra red rays as a means of seeing through fog, is an indication of my view of the utility of such suggestionsin the present state of physical knowledge." board, Mr. Street, an American, and Messrs. H. Bolsoverand F. B. Tomkins, of the staff of A. V. Roe & Co., Ltd. The crew consisted of Mr. J. J. Flynn, pilot, Mr. F. H.Mason, mechanic, and another employee of Imperial Air- ways, Mr. A. C. James, was also on board. Messrs. Street,James and Mason were killed, and Mr. Bolsover died after- wards in hospital. Messrs. Flynn and Tomkins each hadto have a leg amputated. Mr. Tomkins showed great bravery in crawling a mile with his damaged leg to get help.The G.A.P. and A.N. Lectures THE navigation lectures which, as we announced lastweek, would be held under the auspices of the Guild, by kind permission of the Air Ministry, at Gwydyr House,throughout the winter, started on Tuesday evening. Some 20 aspirants to the second-class navigator's ticket attendedand Mr. Collins had a keen and appreciative audience for his first night. The first few lectures will, of necessity, be of anelementary character, since many of those attending, even if they have the necessary mathematical knowledge, haveforgotten it, and these preliminary lectures will serve to refresh their memories with the essential matters concerninglogarithms and trigonometry. The regulations require a navigator to be an " X " chaser in a small way and withoutsuch lectures as these there is no doubt that many people who have been out of touch with such matters—while havingturned their attention to flying matters—would find a great deal of difficulty in passing the examination. The regulationsas to what is required of a navigator seem to warrant close investigation and next week we shall have something more tosay about this. - 1227
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