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Aviation History
1957
1957 - 0312.PDF
314 FLIGHT, 8 March 1957 More than 7,000 rounds per minute in 1916—a rare photograph of the Fokker-Leimberger gun described by Mr. A. R. V/eyl. CORRESPONDENCE ... aircraft and engine suppliers, on August 16, 1916. It pointed outthat all current airborne firearms suffered from their relation to the demands of ground-borne forces. Airborne weapons shouldbe very light; have a high rate of fire, lasting a few seconds; lend themselves to handling at aircraft speeds of over 130 m.p.h. andat high altitudes (with temperatures of -40 deg C); require little space; and eventually be practical for firing vertically downwards.Siegert suggested operating such guns mechanically, either by the aero-engine or by the electrical power-sources carried for thewireless gear. They should, he said, be multi-barreled. He invited new ideas from firms formerly unconcerned with firearms,and offered financial and material assistance for experimentation: manpower, aero-engines, trial weapons and other facilities wouldbe made available at once. This very sensible memorandum produced a whole crop ofengine-operated aircraft weapons (Siemens, Autogen, Szakatz- Gotha, Fokker, etc.) and some startlingly good ideas. None ofthe guns became operational during the war; but at least one type (the Siemens) was operationally tried on the Western Front, anda victory was achieved with it in air combat. There is little doubt that these weapons would have become effective had the war lastedinto 1919. Fokker and his right-hand armament expert, H. W. Luebbe,produced several designs. One had a direct drive by a crank of an otherwise normal Maxim-gun mechanism.* The other was therevolutionary Leimberger 12-barrel gun. This was fired soon after the issue of the memorandum mentioned above. The barrels,which were mounted within a drum-like rotor, were normal, except for the fact that each breech was half cut-away along theaxis of the bore. The matching other half of the breech was formed by a corresponding depression in a second drum-like rotor(of smaller diameter); this rotated underneath the barrel cylinder. When the two breech halves of these rotating parts married up,spur-gear like, the barrel concerned attained its firing position, with the cartridge in place. The feeding belt with the cartridgeswas carried right through the split breech of the two rotating elements, like a chain between sprockets. The cartridges were notextracted; after the firing the spent cases were still in the belt. There was no reciprocating breech block. Firing took place, bypercussion, when the breech closed perfectly (firing pin on swash- plate). The gun was, therefore, extremely simple (as is the VulcanT.161). It was devoid of any reciprocating parts, and free from the extraction troubles which afflicted the Maxim gun. Moreover,it could fire at any speed. The upper rate of fire was limited solely by centrifugal stresses, and by the time which the powder neededfor burning. In air combat, the gun was intended to be pre-rotated so as tofire at top rate as soon as the trigger released the cartridge feed. This was necessary, since otherwise too much time would be lostin accelerating the mechanism. There is no record of the ballistic behaviour, but it would seem that the long calibre-lengths of thebarrels might adversely affect the stability of the bullet. There can be little doubt that the barrel material had a long life, consider-ing the air-cooling and the low sequence of fire through the individual barrels. Versions of this rifle-calibre gun were fired at a rate of over7,200 rounds per minute. The weapon, however, suffered from too many jams. The quality of German cartridge-case materialhad seriously deteriorated, and only too often the cases tore open in the gun. Dunstable, Beds. A. R. WEYL. :- * British Patent Specs. Nos. 136821-136824. -.,-- ,. . - All-through Jet TrainingH OW is the statement of the Hunting Percival spokesman on pp 230-231 of your February 22 issue (that "present indica- tions are that the overall cost per pupil trained to Wings standard will be several thousand pounds less on the Jet Provost/Vampire sequence than on the Piston Provost/Vampire sequence") to be reconciled with the reply to a questioner given in the House by the Secretary of State for Air on February 13? The Times of the following day reports the Minister as saying that the change from the Prentice/Harvard/Meteor sequence to the Provost/Vampire sequence alone had increased the cost of training a pilot by £10,000. Does this mean that there is some vast difference between the cost of the Piston Provost/Vampire sequence and the Prentice/ Harvard /Meteor sequence? Clifton, Bristol. N. C. F. BLOY. [We invited Hunting-Percival Aircraft, Ltd. to comment onthis letter. Their observations follow—Ed.] "The purpose of the Jet Provost is not only to introduce the pupilpilot to the turbojet-powered aircraft from the very beginning of his training as a pilot, but also to provide him with experience on jet-flyingtechniques (which differ so fundamentally from those of the piston engined propeller aircraft) in the most economical way possible com-mensurate with the performance necessary to achieve this aim. "Having accepted this principle, the saving in costs between the JetProvost/Vampire sequence and the Piston Provost/Vampire sequence should be considerable, since time previously spent on learning jettechniques on the expensive advanced trainer (Vampire) can now be saved by learning these on the basic trainer (Jet Provost). "The Jet Provost is less expensive than the Vampire, its fuel consump-tion is half that of the Vampire and its maintenance man-hours about a third; therefore, any transfer of flying time from the advanced jettrainer to the Jet Provost will effect a large saving in costs which will more than offset the increased fuel costs of the Jet Provost over thoseof the Piston Provost. "The reference to the Piston Provost/Vampire sequence taking overfrom the Prentice/Harvard/Meteor sequence is irrelevant, since this marked the introduction of the two-stage training scheme, with itsobvious economies, some four years ago; and the present task is to bring to light the advance in training methods and economies by comparisonbetween the new Jet Provost/Vampire sequence and the current Piston Provost/Vampire training syllabus in the Royal Air Force. "The cost of training a Service pilot must inevitably increase propor-tionally to the increased cost of the operational aircraft for which he is being trained to fly, and to command which he must always be a veryproficient pilot in all respects." Squadron History ON behalf of No. 204 (City of Lincoln) Squadron, Air TrainingCorps, may I, through your columns, request any information on the history, aircraft, markings and serial numbers of No. 4Squadron, R.N.A.S., prior to April 1,1918, and thereafter No. 204 (G.R.) Squadron, R.A.F.? I am trying to prepare an authenticillustrated display covering the history of these units and any information your readers may care to send me at "Rocklands," 61Greetwell Road, Lincoln, would be much appreciated. Lincoln. C. PHIL. STEPHENSON, P/O., R.A.F.V.R.(T.), No. 204 (City of Lincoln) Squadron, A.T.C. FORTHCOMING EVENTS Mar. 8. 12. Helicopter Association: "All Weather Operation of Heli- copters—Engineering and Piloting Aspects," by P. A. Hearne, D.C.Ae., and J. W. Read, D.F.C. R.Ae.E.: Section Lecture" "High Temperature Materials for Engines," by E. R. Gadd. 13. Royal Society of Arts: "The Air Training Corps," by W/C. Norman Macmillan, O.B.E., M.C., A.F.C., D.L., A.F.R.Ae.S. IS. Institute of Transport: Annual Dinner, Dorchester Hotel. 19. R.Ae.S.: Graduates and Students Section: "Gas Turbine for Helicopters," by A. W. Morley. 21. R.Ae.S.: Section Lecture: "Application of Automatic Digital Computers to Aeronautical Problems," by Dr. S. H. Hollingdale. Mar. 26. R.Ae.S.: Main Lecture at Reading: "Present and Future Developments in Civil Aviation," by P. G. Masefield, M.A. (Eng.), F.R.Ae.S. 1-6. Southampton University: Course on Aircraft Acoustics. 4. R.Ae.S.: Main Lecture: "Engine-Airframe Integration," by L. F. Nicholson, F.R.Ae.S. 5. A.B.A.C: Annual Dinner, Waldorf Hotel, London. 6. British Interplanetary Society: "History of Rocket Development in the Walterwerke," by H. Walder. Mar. Mar. Mar. Mar. Mar. Apr. Apr. Apr. Apr. R.Ae.S. Branch Fixtures (to Mar. 20) Mar. 13, Bristol, Fourth Barnwell Memorial Lecture, "Education in Industry," by Prof. A. R. Collar; Manchester, Second Chadwick Memorial Lecture, "Influence on Aircraft of Aeronautical Research," hy M. B. Morgan; Southampton, "Production Development," by L G. Burnard; Weybridge, "Problems of Jet Transport Operation," by J. T. Dyment. Mar. 14, Isle of Wight, "Fleet Air Arm Tactics and Strategy," by Capt. D. R. F. Cambell; London Airport, "Problems of Jet Transport Operation," by J. T. Dyment. Mar. 15, Birmingham, "Medical Aspects of High-Speed Flying," by G/C. W. K. Stewart. Mar. 18, Derby, "Operational Problems of Jet Airliners," by W. O. W. Challier; Henlow, Film Show. Mar. 19, Glasgow, "Titanium," by R. L. Preece. Mar. 20, Brough, "High Speed Flight," by Col. C. Yeager; Christehurch, "Aviation Journalism," by C. Gardner; Merthyr Tydfil, Talk by Member of Douglas Aircraft Co. \~ V "-. ..". :
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