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Aviation History
1933
1933 - 0501.PDF
FLIGHT, SEPTEMBER 7, 1933 An Easy Course Calculator ONE of the simplest Course Calculators we have seen is that invented by Mr. P. Goudime-Levkovitsch and made by W. G. Pye & Co., Newmarket Road, Cambridge. It is also obtainable from the flight office of Airwork, Ltd., at Heston. It will appeal to the ordinary man who flies, because it is so arranged that each of its three dials has only one function to perform, and the chances of making errors are therefore greatly reduced. Any three-vector problem can be solved rapidly. For example, it is easy to find the magnetic course to steer and the ground speed made good when the airspeed, track and wind are known; or, when the airspeed, course and wind are known, the track and ground speed can be ascer tained without recourse to pencil and paper. The ordinary C.D.C., of course, does the same thing, but this new calculator is certainly very much simpler for general use, besides being considerably cheaper. As can be seen in our photograph, the calculator con sists of a transparent rectangular base, carrying three dials engraved to represent the three vectors:—Airspeed and course, ground speed and track, direction and velocity of wind. Each dial has, therefore, only one duty to per form, and any possibility of confusion is thereby avoided. Two arrows "marked MAGN and TRUE are provided a gainst each dial ; it is therefore possible to read off True or Magnetic readings without the need for any calculation. A ruler, engraved with two scales, lies across the three •hats, scale (A) being over the " Ground speed " dial and ^cale (B) over the " Wind " dial. An advantage of this type of calculator is the ease with winch it can be used on a map. For example, we have in the normal course of events a line drawn on the map ^presenting the Track we wish to make good. The calcu lator can then be laid on the map, with its shorter sides parallel to the grid lines on the map, in such a position that the Track Line can be seen through the hole in the centre of the Ground speed Dial. The dial is then rotated T ,the. North and South line on it coincides with the rack Line. The Track required will then be found against the arrow (magnetic or true). When the Track • uns nearly East and West, it is easier to set the calculator S S S British Machines for Australia a A REPORT from Australia states that in all probability : argf order for service machines will be given to British ' ", firms by the Australian Government within the n ext few months. on the map with its longer sides paiallel to the grid lines. The Track Line will, as before, have to pass through the hole in the centre of the Ground speed Dial, but now the dial must be turned so that the East and West line coincides with the Track. After having found the Track in this manner, which for the sake of example we will suppose is 10 deg. true, we will assume that we wish to find the Magnetic Course to steer, and the Ground speed. The Airspeed of our aero plane we will take as being 85 m.p.h. and the wind as blowing at 40 m.p.h. from 150 deg. true. First we slide the Airspeed Scale, which forms the end hinge of the cross rule, so that 85 comes opposite the index line on the metal clip. The Ground speed Dial has already been set as above, so the next thing to do is to rotate the Wind Dial to 150 deg. true. Then, while keeping the edge of the cross ruler on the 40-m.p.h. division of the scale on the Wind Dial, we rotate the Airspeed Dial until the line of Ground speed figures on the Centre Dial cuts the scale (A) on the cross ruler, at the same reading as the line of Wind Velocity figures cuts the scale (B). We can then read off the Course to Steer and the Ground speed. These will be found to be 42 deg. magnetic and 112 m.p.h. respectively. It should be noted that we have without dilficulty found the Magnetic Course to Steer, although we started with a True Track and Wind Direction. Any other three-vector problem can be solved with equal facility. It is easy to find the Track and Ground speed when the Airspeed, Compass Course, Wind Direction and Velocity are known, or the wind can be found when the Airspeed, Compass Course, Drift and Ground speed are known. The Bearing can be found between two places on a map in exactly the same way as the Track was determined in the above example, while a scale of inches is engraved along the edge of the calculator so that distances may be measured off. Another refinement, which can be incor porated at a small extra cost, is a Time and Distance Scale mounted on the underside. The plain calculator only costs 19s. 6d. and is the simplest of its kind which we have met. Its accuracy would appear to be ample for all normal flying. S S 5§ Deutsch de la Meurthe Cup THE AERO CLUB DE FRANCE has fixed. May 27 for the date of the race for the Deutsch de la Meurthe cup next year. The distance will be 2,000 km., in two stages of 1,000 km., with a stop of one hour in between. 893
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