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Aviation History
1917
1917 - 1166.PDF
NOVEMBER 8, f RIPPLING LOflDS OF ASH STRUTS If SQUARE SECTION WITH * CmWMELL SECTION* PIN-CONNECTED EI»DS CURVCS GIVE VrtLVCS OF DEPTH OF GUT? :— ATBTT- SHOWINO CHflRffcTEfflSriCS OF CHANNEL SECTION SHOWN ABOUT THE AXIS XX.THRBftlFORMULA USED IN CALCVLflTIOVS ;-CRIPPLING- LOAD IN PBUNDS= THE CENTER OF G-RAVITY AREA OF SECTION L - LCN&TH Of .STRUT RADIUS fif G-VftftTlOA/ a= C0NST4NJ" WHICH DEPENDS ON THE VALUE OF II I ^~-^ PEPTH OF CUT-D \ ?) .'/• 2' .3' .4' .5' 6' .7" £- 9- I'flT />' i.2y 1.3 LENGTH OF ASH STRUT IN INCHES. Fig. 7. the above formulae and see what cripppling load our chosen section will have. This usually falls above or below our required load, and so several values of area must be tried. This involves much computation, and, in order to avoid this, the accompanying charts have been constructed. Fig. 2 represents a universal strut chart which, as the name implies, may be used to find the crippling loads of struts for any section, material, length, and also for various end connections such as round, fixed, or one end round and the other fixed, and for any experimental data. The sections shown are stream - line, square,hexagonal, octagonal, and circular. In the upper right hand corner of the chart there are plotted ex-perimental results of R.A.F., Clark, and Hunsaker.* R£* R.A.F. data, "FLIGHT," October 18th, 1913, p. 1149. Clark's data, Aerial Age, August 7th, 1916, p. 635. Hunsaker's data, Aerial Age, August 16th, 1916; and Aviation and Aeronautical Engineering, June 15th, 1917, p. 442. . Air Fighting in October. IN its excellent summary of air fighting, on the Western front, for the month of October, the Tiptes says :— " It is impossible to give the precise figure of air losses on the Western front during October owing to the fact that the fighting on the 13th was so close that, in the words of the official British report, ' the number of hostile machines accounted for could not be determined by our pilots.' Several enemy aeroplanes falling out of control were, however, seen by other pilots who arrived too late to take part in the fight. The number actually reported by British, French, and German headquarters as having been shot or brought down, or driven down either completely out of control or in a damaged condition is 399, of which 281 are claimed by the Allies and 109 by the Germans. The enemy has not yet made a claim to the nine British machines which were reported missing in last night's communiqtti. This total is 47 more than half that for September, when the figure was 704, and compares with 428 in August. " Including those of the Royal Naval Air Service, the pilots Fig. 84 jFrom this universal chart special charts may be constructed which show at a glance the size of strut necessary for a given load and length. These are represented in :— Fig. 3 for square ash sections : R.A.F. data. Fig. 4 for square spruce sections : Hunsaker data. Fig. 5 for stream-line spruce sections : R.A.F. data. Fig. 6 for octagonal spruce sections : R.A.F. data. Fig. 7 for channel ash sections : R.A.F. data. All of these Figs., 3 to 7 inclusive, are for pin- connected ends. The channel section shown in Figs. 7 and 8 is very interesting. As is well known, the longerons of the body are often channeled out for lightness. The section shown is ij in. sq. ash. The least radius of gyration occurs about the axis XX, Fig. 8, and if we take these values of area and radius of gyration and use them in the universal chart, we may construct Fig. 7, which shows the depth of channelling for any length and load. . , . • ' of which carried out during the month almost daily raids on enemy bases in Belgium and patrols, the British losses amount to 109 machines. Against this our airmen and gunners on the battle front and our naval airmen brought, down 113 enemy machines, and drove 73 down out of control. The record of the airmen acting under the Admiralty is a very fine one. They destroyed 11 and drove down 13 other machines, with a loss to themselves of only four machines. Sir Douglas Haig made the interesting announcement on October 22nd that the Naval Air Squadrons attached to the Army have been fighting throughout recent operations, and have accounted for a large share of the enemy machines brought down, and that the Australian Air Squadrons have also begun work on the battle front. " The number of German machines accounted lor by the French was 95, but it is difficult to say exactly how many of these were destroyed, because the Ministry of War, in reporting the fact that 25 fell to their pilots on October 24th, did not distinguish the number brought down and those driven down out of control."
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