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The Cazaux Effect trails seems to have been a dog-days topic, dragged out through the winter of 1938. I quote the major citations in _Flight_, but as will be clear, to the extent that there is anything to the story, it will be found in the April 1937 issue of RAF Quarterly. The following blurb appeared at the foot of the "Service Aviation" section in the 6 January, 1938 issue of _Flight_ (p. 22), often a repository for the unsourced and fantastic. "A most disturbing bugbear which confronted armament technicians as the speed of military aircraft rose above 200mph --the problem of training free guns-- has been routed by the introduction of some ingenious power-driven gun turets as typified by the Nash and Thompson models specified for some of the British machines. But life is far from easy for the ballisticians are now confronted with what threatens to become an even more formidable obstacle --the deflection of bullets fired at angles to the line of flight. [paragraph break] On the Continent the problem came into prominence during trials from the French multiplace de combat machines at Cazaux, the proving ground of French aircraft. It was discovered that although some most impressive arcs of fire were obtainable on paper, the deflection of bullets fired broadside detracted very seriously from their fighting value. [para] The logical step to take against this phenomenon is to increase the muzzle velocity of the bullets. This could be achieved by lengthening the gun barrel or increasing the propulsive charge, both of which measures have obvious limitations. [para] The large orders which have been placed for power-driven turrets in this country might indicate that l'effet de Cazaux might not be so serious where small-bore, high velocity guns are concerned, as is extensively velieved, but, whatever the true facts, it seems that deflection of bullets and shells may be a prominent factor in undermining the value of multi-seat fighters with free armament." This is the issue covering the New Year's Honours List, so I would expect wide attention --but the kind that comes with the wild glee or sick trepidation that comes when you open that letter from your publisher/the Social Sciences and Humanities Research Council. Perhaps this is why it took until the 3 March, 1938 Correspondence section (page 205) for the following letter from John North to appear. " I notice that, in your issue of 17 February, in the course of an article on two-seater fighters, [NB, H. F. King, "Two-Seater Fighter: Will They Survive?" _Flight_, 17 February 1938: 154--156, which in turn references the 6 Jan citation above] the author makes the statement taht "any hope of broadside fire seems more assuredly doomed as speed increases --in other words, the question of broadside fire is affected by the high speeds now attained, as waas explained in a note a few weeks ago . . . . on the 'Cazaux Effect.'" [the first para. is then cited]. "I put to you, as counsel would say, that the story of the effet de Cazaux is a myth. As, however, this statement attepars in your paper as one of fact, and has also been made by Gen. Golovine and his anonymous collaborator, I would particularly invite those who are responsible for publishing these statements to furnish the following information:-- [following the original's point form for clarity] (1) When did these experiments take place? (2) What aircraft were used, and what was the speed of the aircraft from which the firing took place? (3) What type of target was used? (4) What arm and ammunition was employed? (5) What was the precise nature of the effect observed?" -John D. North. The editor replies: "Frankly, the anwer to Mr. North's comprehensive list of questions is that we do not know: we can give no specific answers, but only recall taht when the big French multiplace de combat machines, originally regarded as aerial battelships, were put through their firing tests at Cazaux four or five years ago, one not onlyl read in responsible publications, but was told emphaticallyl at the Paris [Air] Show, that the accuracy of their broadside fire was noticeably impaired. It may be significant that these machines are now regarded solely as bombers. Another point is that, so far as can be gathered, all new high-speed twin-engined fighters being built on the continent have no power-driven turrets --merely guns with a restricted arc of fire toward the rear. [para] However, Mr. North's association with the excellent Boulton turrets is not to be disregarded; if anyone knows anyting about broadside fire at high speeds it should be he. So we are very happy to publish his letter in the hope that someone may come forward and aid in throwing ling on a subject which is tremendously important just now." The Editor [C. M. Poulsen.] The correspondence page for the 20 March 1938 issue (p. 242) has two replies. "British aviation pioneer" --here taken as code for "mostly harmless eccentric, unless you set foot in one of his designs"-- W. O Manning writes referencing the Magnus effect. He suggests that its magnitude could not be calculated in this case because of supersonic aerodynamic effects. More seriously, someone signing himelf "Tactician" with a London address [so we infer a serving officer with a Ministry appointment] replies, in part that C. Rougeron, the new Directeur des Armaments Aerien at the French Air Ministry published comments on the lessons of the air war in Spain in the April 1937 issue of Royal Air Force Quarterly which the author takes as proving the reality of the Cazaux effect, for which he refers the reader to _Les Ailes_ for 15 March 1934, page 7; and 19 April 1934, page 6. However, "Tactician" only quotes Rougeron to the effect that "the fire of bombers outside the axial plane is almost impossible with the present speeds and it cannot, in any case, be accurate." This is in itself justified by the sheer difficulty of wrestling with free guns in a high speed slipstream. It says nothing about mysterious gyroscopic effects on the bullet. Manning may not intend to introduce the red herring issue of the effect of the aircraft's relative velocity on the well-known phenomena of drift that I so underrated in my last post, but that would seem to be the effect (at least on me!) The next useful installment is another letter from "Tactician," to the effect that the trials were of multiplace de combats capable of "almost" 200mph, and the weapons were free Darne rifle-calibre weapons. Indicative of the way the discussion is going (and of Tactician), he then appends; "Perhaps Mr. North can tell us something of a new effect noticed, I believe, at heights over 15-17,000ft, due to the change of sound velocity at attitude. Apparently, the Cazaux effect is less noticeable at such heights." On 21 April 1938, North replies, in part, that he still does not know what the Cazaux effect is, "or even if it exists." (Flight, etc., p. 390), speaking for all of us still. The editorial for the 19 May 1938 issue jokes about l'effet de Cazaux. To the best of my knowledge, this is the last reference to the alleged phenomena, which hereafter drops of the radar screen. A few weeks later the editor slyly notes the appearance of turret-equipped Demons at a special RAF show for invited MPs as evidence that a major new turret fighter contract is forthcoming, but overall the press coverage of this whole story is obscured by the intensely stage-managed public debute of the Hawker Hurricane, complete with that famous 409mph average speed flight from Edinburgh to London. On this basis I suspect that the notices in _Les Ailes_ will prove less than helpful. (As we should hardly be surprised from a weekly about garlic. Only in France....) What may be useful are the archives of _Flight International_, which may contain additional correspondence, and certainly the identify of Tactician. Is he just dragging up some red herrings, or is he playing some serious game. And, of course, there is the question of "General Golovine and his anonymous collaborator." Aside from his reputation as an author and air power theorist, I know very little about General Given the interwar aviation business, I would be totally unsurprised to find a commercial interest lurking here somewhere --probably, and this is a wild guess, Oerlikon. Erik Lund Elunderik@Netscape.Net ----- For subscription help, go to: http://www.h-net.org/lists/help/ To change your subscription settings, go to http://h-net.msu.edu/cgi-bin/wa?SUBED1=h-war -----
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