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Aviation History
1918
1918 - 0913.PDF
AUGUST 15, 1918. • THE PILOT'S "OFFICE." INSTRUMENTS FOR AIR USE. " , By Lieutenant WILLIAM A. ROBSON, R.A.F., Author of "Aircraft in War and Peace." [The following short summary of the chief instruments, &-c, by Lieut. W. A. Robson,R.A.F., will afford the information to a number eg of prospective pilot enquirers who have now and again asked for enlightenment in this direction.—-ED.] LET us take a look into an airman's office. I do not refer teach the young pilot never to become the slave or dependent to the wooden hut on the ground where in bad weather of mere instruments. cigarettes are smoked, the illustrated weekly papers read, Next we have the tachometer or "rev. counter," which and aerial operations discussed in professional slang.p p gI mean the " office " where the pilot does his real work ; and this is the name which for some inexplicable reason has been given to the cockpit of an aeroplane, wherein sits the aviator. To the uninitiated it appears a confused medley of dials, recording needles and levers ; mysterious, unfathom- able, exciting. But to the trained airman these things are as an*open book; and each one of them is in some way- essential to the control of the machine and its manoeuvres. The most important of the instruments is the compass. Without its aid an airman who is flying over the sea or over land on a misty day is hopelessly lost. In the R.A.F. great attention is attached to the necessity for every pilot being able to fly a compass course; that is to say, a course along which he is guided solely by his compass; and very great progress has been made in this connection. Thousands of miles are flown every week on patrols over the sea alone, and pilots nowadays very rarely come to grief through losing their way. This is saying a good deal, when the problem presented by drift is remembered. If an aircraft starts from one point to fly to another due East, and there is a wind blowing at 15 miles an hour North-East, that will clearly have to be taken into consideration, and the compass course altered (before ascending) according to the total distance of the journey. Many difficulties had to be overcome in the production of a satisfactory compass for aerial work. Chief among these was that of neutralising the magnetism of the engine (and in particular the magneto) and of preventing the effect of centrifugal force, which caused the card or dial inside the compass to swing in a direction quite independent of North when the aeroplane was banking on a turn. However, a truly excellent compass is now in use in the R.A.F., far superior to that employed by the enemy. And indeed it would be odd if the Germans should have proved able successfully to compete in this direction with a nation whose commerce for several hundred years has been largely dependent on the excellence of its ships' compasses. Probably the next most important instrument is the aneroid or height indicator. This is worked on a simple mercury principle, .and is generally fitted with an adjustable dial which'can be moved round so that the reading on leaving any given aerodrome is zero. Which reminds one of rather an amusing occurrence. A pilot left his aerodrome for a cross country flight on a very misty day, and carefully set his aneroid to o. .After flying for a couple of .hours by com- pass he thought he must be nearing his destination. He could see nothing below him and so descended to 500 ft. On he flew at this height for another five minutes. Deciding to land, he was about to make a magnificent volplane, when suddenly the mist cleared and he saw the ground immediately underneath him, about ID ft. below. His faithful aneroid still insisted that he was 500 ft. high. The explanation lay in the fact that the place he was about to land on was 500 ft. higher above sea level than the aerodrome whence he set out. Trifles like this are all in the day's work, and help to London-Brindisi Aerial Mails. ACCORDING to a correspondent of the Times in Rome, plans have been worked out for an aerial service between Nice, Rome, and Brindisi in connection with the projected London-Paris-Nice service, and in future extension to Brindisi and Salonica. What Aerial Travel will Mean. LECTURING before" the Savage Club, at the Eoyal Automobile Club, on August 7th, Mr. Handley Page said i-hat .an air service between London and Marseilles, with one stop at Paris, was quite possible. The journey from London to Constantinople could be made in 20 hours instead of 72 before the war; Rome couldf be reached in 12J hours instead of 42, and Marseilles in 8 instead of 23. He also gave figures referring to a service providing for 24 machines running a minimum service of six machines each way per day. Such a service, he said, could be provided for on capital of 'ess than half a million, and the annual cost would be under £600,000. The cost*per ton mile would work out at 2ojrf,, and the cost per passenger mile to 1.366?. A600 h.p. machine could carry comfortably six passengers, e , records the number of revolutions the engine is making per minute. This varies from about 1,100 (in rotary motors) up to 1,800 in water-cooled engines. The reading of this instrument is of great interest to the pilot, for modern aircraft are so carefully designed that their performance is effected enormously by even an extra 100 revolutions or so per minute one way or the other. Another important instrument is the air speed indicator. This tells the pilot at what rate he is rushing through the air. This speed, of course, has no relation to the rate at which he is travelling over the ground. Nor is it intended to, for it is air speed which is of importance to the stability of the aircraft and the safety of the pilot. If a machine flying at 70 miles per hour is travelling against a 40-mile wind, the AS. indicator will show no m.p.h. Every aeroplane has a minimum air speed at which it must be thrust through the air if it is to be maintained aloft ; and a maximum air speed in excess of which it cannot safely be nose-dived, for the various components will not stand the strain beyond a certain given point. It can be seen how essential is this device on a flying machine. Air speed indicators have-been fitted to British aircraft for years past and it is interesting to note that the Germans have just com- menced to use them. The next item which calls for attention is the inclinometer. This is a curved spirit level fitted transversely across the machine. It is marked in degrees ; and the pilot can tell front it at what-angle he is banking his craft when turning. With the addition of a miniature set of electric light clusters and a neat eight-day watch the list of instrumental equipment is concluded. The only remarkable feature of the watch is that if an aeroplane is left without a guard for five minutes after a forced landing, the watch mysteriously disappears ! There are several pressure gauges on the dashboard. One for each petrol tank, to indicate the pressure at which air is forcing the spirit to the engine; and another one to show the pressure in lbs. to the square inch at which oil is being driven through the various lubrication channels. On water-cooled engines a thermometer records the tem- perature of the water in the radiator. Space forbids a detailed description of the controls. How- ever, it may briefly be said that there is a swivelling foot-bar for the rudder ; while a central lever, commonly known as the " joystick " actuates the elevation and banking of the aeroplane. A wheel at the side increases the angle at which the tail plane " attacks " the air, this being for rapid ascension. Two side levers control the speed and petrol consumption of the engine. Then come the various articles of military equipment. These comprise the machine guns with their actuating gear, firing straight through the propeller, and controlled by a lever on the joystick ; the wireless outfit in the observer's cockpit ; and, finally, message bags, bomb sights, and camera release handles. And some folk seernto think pilots are not very busy people! totalling goo lbs., and 3,500 lbs. of merchandise, and it would ' be commercially possible to carry the passengers at is. per lb. for 800 miles. Sir Joseph Ward said he had decided, as postmaster- general of New Zealand, to introduce aeroplanes for carrying mails from one end of New Zealand to the other as soon as the war was over. Preparing for the Transatlantic Flight. " FOR the purpose of qualifying American and Allied airmen in this country for the contemplated Transatlantic flight, the United States Military Aeronautical Division has arranged for a great cross-country flight over a distance of 3,000 miles," says the Times correspondent in New York. The flight was to start frpm Dayton, Ohio, on August 15th. Eleven Americans were to participate in it, accompanied by English airmen. The Americans will use Cortiss machines of the " H " type. Halts have been arranged at Cincinnati, Columbus, Toledo, Detroit, Indianapolis, St. Louis, Kansas City, Omaha, Des- moines, St. Paul, Milwaukee, and Chicago, and at each place exhibitions of flying will be given 911
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