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Aviation History
1941
1941 - 2037.PDF
SEPTEMBER 4TH, 1941. FLIGHT 133 FIVE YEARS OLD British Pioneer Work on Contra-rotating Airscrews : Flight Tests Early in 1940 /i LTHOUGH it has been known that the Fairey Avia- /A tion Co., Ltd., has had under development for several *• -*• years contra-rotating airscrews, it has not been possible to say much about this work until now. The external appearance of the airscrew will be familiar to many, for not only was a specimen exhibited at a Royal Aeronautical Society garden party at the Fairey aero- drome some years ago, but pictures of it have appeared in Flight. It was very natural that Fairey's should be early in the field, for with that company's long and close association with Fleet Air Arm work the advantages of an airscrew which does not cause a "swing" were very obvious. There are several other advantages of contra-rotating air- screws, but as these were dealt with in Flight quite recently there is no necessity to repeat them here. Five years ago the Fairey company began investigation and design of contra-rotating airscrews, under the direction of Capt. Forsyth. Manufacture was begun the following year, and a great deal of bench testing in the hangar was undertaken before the airscrew was put on an aircraft and tested in flight. The '' teething troubles '' associated with any mechanical innovation were largely overcome during this period, and by February, 1940, the airscrew was considered sufficiently reliable to be tested out in flight. Since then many service pilots and test pilots have flown behind the contra-rotating airscrew and the con- sensus of opinion seemed to be that in addition to the absence of swing, the rudder, elevator and ailerons were more positive in action than with the orthodox airscrew. The Fairey airscrew is electrically operated by a single reversible electric motor. It is possible to constant-speed or stop the airscrew at any intermediate pitch. At the end of the pitch range a clever electrical device is incor- porated for automatically off-switching the motor. This scheme has worked very satisfactorily. The general operation is by means of gears. There is nothing complicated as the whole unit is so designed that production presents no problems. Another point of interest is that the front and intermediate gear boxes and the airscrews can be removed as complete units. Thus, from a servicing point of view the Fairey contra-rotating airscrews are as easy to handle as other types of airscrews now in use by the R.A.F. and Fleet Air Arm. The diffi- cult problem of lubrication has been successfully solved, and designs are available for obtaining a rapid rate of pitch change, full feathering, and hydraulic operation as an alternative to electric. The airscrew was originally intended for a type of engine still on the secret list, but designs are available to make it adaptable for Service types of engines. Provision is made for a cannon to be fitted through the shaft. Nylon Parachutes ? F testing Nylon fabric, a derivative of coal which is nowused in stockings and toothbrushes to determine its suitability for use in parachutes, the U.S. Army Air Corpsfound that it stood exposure to sun, snow and rain better than silk, but was more susceptible to the effects ofultra-violet rays. The original strength of Nylon is greater than that of silk and it appears that Nylon is at least as goodas silk for parachute manufacture. American Salaries CALARIES of some of the big executives of the American>J aircraft industry are listed in American Aviation. Con- verted to sterling at the rate of $4.03 to £1, these are: J. H. Kindelberger, president of North American Aviation,£41,100; J. L. Attwood, vice-president, £19,500; J. S. Smith- son, works manager, £7,200; Reuben H. Fleet, president ofConsolidated, £8,900; I. M. Laddon, vice-president and chief engineer, £6,350; C A. Van Dusen, vice-president and worksmanager, £5,556*. U.S. Aircraft Manufacture Z"1 RE AT BRITAIN had received about 3,500 military aircraft*-* from U.S.A. since the start of the war up to May last, said Mr. John H. Jouett, president of the AeronauticalChamber of Commerce. About another 3,500 have been delivered to the U.S.A. Army and Navy by the aircraftmanufacturers who have total orders for 44,000 military craft. These will be distributed as follows: U.S. Army,16.500; U.S. Navy, 8,500; Great Britain and Canada, 16,000; Knudsen Plan bombers, 3,600. Women Aircraft Inspectors INTERESTING jobs are open to women in the AeronauticalInspection Directorate of the Ministry of Aircraft Produc- tion. These jobs are connected with the inspection and testingof various aircraft parts, including engines, wireless and elec- trical equipment, kites, balloons, parachutes, dinghies, etc.Candidates should be of not less than school certificate standard in physics or general science and mathematics, or have hadreliable practical experience of engineering testing and inspec- tion. Ability to read engineering drawings, interpret speci-fications, use micrometers and other measuring instruments is desirable. The age limits are normally 21 to 40 years. The rate of pay for an Assistant Examiner is £2 17s. 6d. perweek, plu S Civil Service bonus of 7s. 6d., and overtime is pay-able. There are prospects of promotion to posts as Examiners a- ,j.22o, plus bonus of £19 12s. per annum. Accepted candi- dates will be given a training course of one month with pay.Accommodation is available near the training school at approxi- mately 30s. per week. Apply by postcard to Ministry ofLabour and National Service, Employment Exchange (Room 24), 20, Nelson Street, Bristol, 1. "Smo/ce Jumping" '"PHE U.S. Forest Service has been using parachutes in itsJ- campaign against fires since 1939. Forest rangers have been trained to jump with the 30ft. parachutes ywith steeringflaps and widely-scalloped edges so that they may quickly reach a fire while it is still small enough to extinguish. Afterthey are down small burlap parachutes are dropped with tools, food and a radio set. The jumper carries an emergencyparachute in front of him as well as the standard one behind and on one leg is a coil of rope to lower himself out of anytree in which he may happen to land. His external clothing is a one-piece suit of very stout material and he is gloved andwire-masked. U.S. Army Aircraft DesignationsT HE type letters and numbers of American aircraft will beless mystifying to readers if they realise that they indicate the Government specifications to which they are designed.Thus " P " stands for pursuit (or fighter) ; " B " for bomber; " PT" for primary trainer; "AT" for advanced trainer;"BC" for basic combat trainer; "O" for observation; "A" for attack bomber; "G" for autogyro. These letters arefollowed by a number which is the number of the specification; thus P-40 is the "fortieth pursuit specification." "X" infront of the letter indicates the experimental prototype, and "Y" is the first trial series. Letters "A," "B" or "C"after the figure are lor variations of the specification. Trans- lating " YO-5B " gives "first trial series to fifth observationaircraft specification; second variation of specification." U.S. Navy Designations T~*HE Navy designations correspond closely to this system-*- and "SB" stands for scout bomber (or dive bomber); " PB " for patrol bomber; and " F " for fleet fighter. But fol-lowing the specification letter and number the Navy inserts a letter showing the constructing company. "A ' is forBrewster, "B" for Boeing, "C" for Curtisfe. "D" for Douglas, "F" for Grumman, "L" for Bell, "M" for Martin,"U" for Vought-Sikorsky and "Y" for Consolidated. Another difference in system is that the Navv uses figures forindicating the variations of the specifications. Thus " XF4F-3 " indicates "prototype to fleet fighter specification Number 4;built by Grumman; third variation of the specification."
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