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Aviation History
1961
1961 - 1672.PDF
776 FLIGHT, 16 November 1961 CORRESPONDENCE... and the fixed-pitch wooden ones preceding it. There were un-doubtedly many "teething troubles" with the DC-3's props, but now they have achieved virtually "fit and forget" reliability. At first sight the point about first cost is unanswerable, butif the above answers to the first two accusations are satisfactory, then the increased cost represents an investment which will give asatisfactory return. Some of the secondary advantages accruing from the use of thepropeller are as follows: (1) reduced airport noise, due to both lower frequency and intensity, and to the propeller's superior rateof climb; (2) reduction in the cost of replacement tyres and brakes due to the use of brake pitch, which (again due to greater Frqudeefficiency) is more efficient than a jet's reverse thrust; (3) simplified parking problems, since the damage caused by slipstream will befar less than that caused by jet efflux; and furthermore, with Beta control, backing up to a loading ramp, and even embarking pas-sengers with the engines running in zero pitch, become practical possibilities. The turbofan is sometimes claimed to be an efficient compromisebetween the two methods of propulsion, but what is the fan part of a turbofan but a multi-bladed, fixed-pitch propeller, renderedeven less efficient by running in a duct ? In conclusion, one may ask whether the airlines, in orderingbigger, noisier and more expensive jets, are really doing their job of providing a safe, fast and cheap alternative to surface travel. Thisis not achieved by flying "expense-account" passengers and a few wealthy people across the Atlantic in the lap of a luxury carried toalmost ridiculous extremes, but by firms like Silver City flying Mr and Mrs Everyman, the kids and the car to France or elsewherefor their summer holiday. The best money-making aircraft ever built to date is undoubtedly the DC-3. Surely the reason is that it ischeap, reliable and adequately comfortable for the stage-lengths of which it is capable: not luxurious, not silent, not vibration-free,but cheap to buy and to fly and as reliable as the proverbial train. Suppose that instead of making bigger, faster and more concrete- devouring jets, the manufacturers built smaller, slower and cheaperSTOL aircraft capable of operating from any quarter-mile strip of grass. It should be possible to operate an aircraft of this type overstages of up to 500 or 1,000 miles at fares comparable to the 2d-odd per mile currently charged by British Railways. It is pointed outthat 1,000 fares at £5 each amount to the same sum as 20 at £250, but there are many thousands more people with the former sum tospend on travel than the latter, so the potential market is immense. This is the way to make real money out of flying aeroplanes, asSilver City have found, compared to some other carriers' "profits" which are confined to the annual accounts. In this connection it may be remembered that the Breguet 941,whether or not a success technically or commercially, is in its way as much of a technical break-through as were the Boeing 247 andDC-3. This is because it is not designed to fly higher and faster, with a bigger payload, than any other aircraft of similar all-up weight,but rather that it must take-off and land in less space, and be cheaper to operate than any other comparable aircraft, whilstmaintaining a reasonable cruising speed and altitude. This is the sort of aeroplane to make money, not "prestige."Indeed, to paraphrase a well-known (propeller-driven) aircraft advertisement, "all the propeller can offer operators is a way tomake money." Stevenage, Herts S. REW STOL in 1919 YOUR photograph in your issue of October 26 of Vedrines'Caudron on the roof of the Galeries Lafayette reminds me that when I was at the North-Eastern Area Flying Instructors'School at Redcar in January 1919 we heard of the occurrence, which was I think to earn a prize for the first roof-top landing. We told the CO, Maj MacMinnies, that Harrods were offering aprize of £1,000 for the first aviator to land on their roof. The major at once wrote and offered to do so, only to receive a replythat they were prepared to pay him almost that sum to keep off their roof! London SW1 G. M. KNOCKER Gp Capt (Ret) Air Traffic Control by Computer PHASE 1 OF SATCO SYSTEM IN SERVICE A RECENT visit to Amsterdam's Schiphol Airport enabledme (writes a correspondent) to see the operation of SATCOPhase I at close quarters and to obtain some impressions of its capabilities. My hosts were the air traffic control staff and,later, representatives of Hollandse Signaalapparaten NV, of Hengelo. The introduction by Signaal of this equipment, and the additionalcomplementary equipments to come, represent a great step forward in the advancement of traffic-control techniques. This year theNetherlands Department of Civil Aviation has gained some experi- ence in the operation of Phase I in its ATCC at Schiphol. Therewas an initial "debugging" period and one for training purposes in 1960, following which SATCO ("Signaal Automatic Air TrafficControl") was put into operation in January of this year. Phase I consists of a fully transistorized, unduplicated digitalcomputer with teleprinters and strip-printers as the means of input and output. The system covers the airways and terminal areas inHolland and also caters for "off-airways" flights in the FIR. Its main purpose is to serve the controllers in the Area ControlCentre at Schiphol by providing them with a rapid means of calcu- lating all types of flight-path and by displaying the results in theform of printed progress-strips, which are then used for the regu- lation of traffic in much the same way as was the old manual system.The increase in efficiency and the saving in labour expected from this phase will thus chiefly concern mental arithmetic and clericalwork. Technical experience so far has suggested that the performanceand reliability of the computer are satisfactory. Apart from half a day's maintenance per fortnight and two periods of one week each(when the system was switched off for major changes) the computer has now been operating 24 hours a day since October 1960. Duringthis time there have been 17 breakdowns (each averaging about one- and-a-half hours to trace and rectify) thus giving a serviceability factorof a little more than 99 per cent. With the duplicate computers which will be installed in Phase II it is expected that serviceability will bevery close indeed to 100 per cent. The great majority of failures concerned transistors. Out of more than 8,000 transistors in thecomputer, 40 failed during 11 months of operation. By con- trast, of the 3,000 diodes, only one failed; and there have been nofailures of resistors. Performance of the main memories—ferrite core stores and magnetic memory drum—has been entirely satis-factory. The performance of the input/output printers has not been as good as that of the computer itself, but the situation has now beenmuch improved by replacing the original equipment with printers of a later type from the same manufacturer. The noise of theprinters has been damped by a novel design of sound-absorbing cabinet. Each printer is installed in one of these cabinets, andalthough they are within a few feet of the controllers they operate without distracting them from the R/T and telephonetraffic. Operationally, many lessons have been learned. The principallesson is that, even with inputs and outputs that differ only very slightly in format and presentation from those of the old manualsystem, "on the job" training of assistants and D-controllers is unwise. Although some initial training was, of course, given withsimulated traffic, it proved insufficient. The result was that in the first two or three months of operational use, both controllers andATC assistants—particularly at peak periods, when they naturally had no time to bother with new-fangled gadgets—tended to revertto the old ways of ball-point and paper. Since then, however, two major changes have been made in the programme unit of thecomputer. Additionally, the controllers found that the colour of the paper strips under artificial light left much to be desired; soboth the quality and the shade of the blue strips has been improved, and certain other changes in organization have been made. Allthese modifications are designed both to meet the criticisms 'of the controllers and to make the switch from manual to automaticmuch more smooth than was originally thought necessary. The impression one gets in the Schiphol Centre is certainly oneof great neatness of the format of the flight strips; one also feels that here is the beginning of much saving in time and effort ofthe kind currently expended in most ATCCs of the world. All flights through Schiphol are now put through SATCO. Forvarious reasons (perhaps tinged with the fact that traditions in ATC die hard) some controllers and assistants did not appeartoo happy with their new toy; but the majority appear to be satis- fied and, indeed, some are noticeably enthusiastic about the system.More important, the lessons that have been learned have proved invaluable in the design of Phase II, which is now in productionand is scheduled for delivery towards the end of 1962. In the introduction of any automatic system of this nature thereare bound to be teething difficulties on both sides. To some, inevitably, the computer is to ball-point as the diesel is to steam:but whatever the opinion of the drivers—as Signaal themselves point out—their system cannot replace the controller.
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