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Aviation History
1955
1955 - 1420.PDF
532 Five alternative types of rotor blade designed by the Parsons Corporation for the same helicopter. (Right) Fatigue testing of a specimen section. ROTOR BLADE PRODUCTION . . . processes in course of development (which would soon be avail-able for use in production) for the testing of bonded joints. He considered the question of commercial existence to be mostimportant. In his view, the position was that the Corporation were able to provide a good service to the helicopter manufac-turers. At the present time, new designs of helicopters were in course of development with a specification for two alternativedesigns of rotor, one to be manufactured by the helicopter con- structor and the other by his own independent firm. In this way,healthy competition was provided and the helicopter project had a greater chance of success. With their streamlined organizationthey could usually produce blades more quickly than could the larger helicopter constructors themselves. They had had no blade failures which had resulted in catas-trophe. On one occasion, when a blade had failed through fatigue, it had done so because greater loads had been imposed upon it(during a series of special flight tests) than the blade had been designed to take. The helicopter had landed from hovering flightand the portion of the blade which had failed was available for inspection afterwards, providing useful scientific data. Bladesdesigned in the future would probably have a longer service life and would be less costly, but there would probably be no greaterreduction in blade weight. Mr. Price left certain other questions to his co-author Mr. Stulen. Mr. Stulen said that the method of sheet-metal blade construc-tion had been adopted for reasons of economy and because tooling for such a method was easier. The honeycomb section for thetrailing edge was difficult in production and was difficult to handle and contour accurately. He said that his corporation did,in fact, carry out considerable analysis into blade flutter, resonance and frequency problems, but testing was necessary to confirm thatthe results of the analyses were correct. He thought that the principle of riveted blades should not be completely rejected, butthat bonding methods were becoming more reliable and new adhesives were being developed to withstand temperatures of theorder of 500 deg. F. The manufacturing techniques were being adapted to bladeshaving a chord as large as 29in, equivalent to a rotor diameter of 82ft. The figure of 14,000 Ib/sq in took into account the scatter,the average endurance for the spar in question being 28,000 lb/sq in. Control of weight and e.g. position was certainly an importantproblem. The majority of the Parsons blades had been produced in matching sets, and one of the reasons for developing the metalblade was that blades could be matched to a master blade and so all be built to the same weight. Production of metal blades, how-ever, was not entirely straightforward, for a variation in the gauge of the metal sheet of a few thousandths of an inch could makea considerable difference in the total weight of the blade. It might be necessary to pick three groups of master blades, building someblades to one master and some to another. CORRESPONDENCE The Editor of "Flight" does not hold himself responsible for the views expressed by correspondents in these columns;the names and addresses of the writers, not necessarily for publication, must in all cases accompany letters. Russian History .:'"..I T is good to learn that there are also air historians inside theSoviet Union, and I expect Mr. Meo's letter will have been read with much interest Flight, August 12th, 1955). There are two or three points that should be queried. Presum-ably the date of 1885 for the invention of Aleksandr Fedorovich Moshaiski's aeroplane is a misprint for 1875. If it flew in 1882 thedate of 1884 mentioned by Gumilevski in Krylya Roding, p. 16 (Moscow, 1954) is also a misprint. The date 1882 is supportedby all other references, such as Mr. Allward's notes in Flight, July 17th, 1953; Wennerstrom in Roda Virigar, p. 9 (Malmo,1946); and an article in Letectvi, R. XXIV, 370 (1948). If, as Mr. Allward mentioned, the official records no longer exist, it is difficultto decide the nature of Moshaiski's achievement. It appears that the take-off was made from an inclined ramp, but it would bevaluable of we could learn the length of the flight or "hop." It is good to see attention drawn to the work of Grigorovich,which is certainly insufficiently known and appreciated outside Russia. In the 1920s and 1930s he built many fighters, and N. N.Polikarpor worked with him. In the latest issue of the "Great Soviet Encyclopaedia" (I quotefrom the German extract Flugwesen II, published by Fachbuch Verlag G.m.b.H., Leipzig, 1954) the priority for a Russian seaplaneis accorded to I. M. Gakkel, who produced an amphibian in 1911. As for flying-boats, the first one is said to have been made byO. S. Kostovich, in 1911. A Russian licence, No. 25702, was awarded in 1913. The encyclopaedia concedes that at the time ofthe work of Gakkel a seaplane was made in France by Fabre. Nesterov looped, not on an M-9 (though I think a Walrus hasbeen looped!), but on a Nieuport of some sort. This was on August 27th (September 9th, N.S.) 1913. The story goes that hewas awarded C.B. for unnecessarily risking Government property! This date is given by Gumilevski on p. 59 of his book and issupported by other sources. Okehampton, Devon. DENYS J. VOADEN. Radio Recollections T READ with great interest Mr. P. Oomen's In Memory of MF-*• and MF/DF in your issue dated August 5th, 1955. While not concerned with World War I, I also have a very "soft spot" forthis now extinct but very important trade, having been a D/F. operator on MF and also HF D/F. during World War II.I, too, can vouch for the amount of pride that each set of operators had in their work and D/F. stations; and—without boasting—OB6 Bottesford was once recognized as "the most efficient D/F. station in 5 Group. One or two instances still remain vivid in my memory andthere was, as Mr. Oomen states, a great feeling of satisfaction when one had helped some particular aircraft to return to baseunder difficult conditions. One instance I distinctly remember was homing a Manchester back to its base at Coningsby after aparticularly hazardous return on one engine in extremely bad QBB and appalling QBA. Although this aircraft was calling 5 GroupHeadquarters B3S with S.O.S., he was slightly off frequency and as our frequency was only a few kc/s off Group, I heard him quiteplainly. After contact he gave a plain-language message telling us of his plight and then proceeded to QDM all the way home. Some20 to 25 QDMs were passed and eventually the wireless operator on board finally rang through to me and informed me that theaircraft had arrived at Coningsby safely and that he wished to thank D/F. for their co-operation in this matter. There was always present, as Mr. Oomen states, "a certain codeof good behaviour and politeness," and I remember very well his descriptions of GM (good morning), TU (thank you), etc.; butthere were also abbreviations of a not quite so polite nature. I can honestly say that on D/F. I spent five of the most fascinat-ing years of my life and even now, if it were possible, I would give anything to "have a bash" at the old morse key and goniometerand would willingly exchange my present occupation with some fortunate D/F. operator. J. MERCER Blackburn, Lanes. (Ex-1077165, "OB6").
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