FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1952
1952 - 1160.PDF
5i8 FLIGHT, 25 April 1952 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. Tandem-wing Configurations P ERHAPS my letter on the Gremlin (February 15th) did not make it clear that this was proposed by me as a personal con ception of a possible low-priced light aeroplane and was not designed by Westland Aircraft, Ltd., although many years ago they made considerable wind-tunnel research on swept-back and tandem-wing configurations, as well as modifying a Lysander to the latter form. I flew both this Westland machine and M. Delanne's "scale model" of the fighter illustrated in your issue of Flight on April nth and so can confirm "Pedantica's" assertion that this type is stall-proof in the accepted sense, and easy to fly. It was partly because of this safety factor that the Gremlin was envisaged with tandem wings of similar arrangement, but I was chiefly influenced by Mignet's Pou (of similar characteristics) which, above all, showed how compactly and cheaply a practicable machine could become through utilizing two wings to give the necessary area and effectively disposing of tail and long fuselage. That M. Delanne had any magic formula is perhaps an exagger ation, but there is necessarily an optimum relationship of stagger and gap/chord ratio, which depends on the particular wing plan- form under consideration. I remember that in the Westland wind- tunnel it was found that even the reverse arrangement had possi bilities, wherein the front surface was a low-winger and the smaller aft wing was mounted high on the fin. It was not necessarily of the identical efficiency which the Mignet or Delanne arrange ments could give, but in any case I doubt whether even at their best they are as efficient as a conventional wing, because drag increases as well as the lift with any form of tandem arrangement. "Pedantica" correctly implies that a nose engine-position would equally well suit the proposed Gremlin, but my third consideration in arriving at the final layout was that the overwhelming advantage of the tandem lies in the abnormally aft e.g., which can be utilized while still giving the stability associated with conventional aircraft. Because of this it would be possible to mount a very light engine right aft of the flying surfaces, when the propeller not only would be shielded from Zebra Club members, but would enable the pilot to be placed in the extreme nose with unobstructed vision, thus maintaining the familiarity of position which he might have acquired in obtaining his initial training on a glider. I am sure that anyone could go solo on a Gremlin without further tuition if he had had practice on a club secondary sailplane, always provided the Grem lin flew with the same ease of handling afforded by the Delanne, Mignet and Westland machines. Yeovil. H. J. PENROSE. Fatigue Failure Y OUR contributor Richard Howard ("Fatigue Failure," April nth), is not correct in his statement that "the proneness of metals to fatigue failure was first observed some time after Holmes had published his poem" (1880). A number of experimenters had observed the effects of repeated stress on metal parts in the first half of the 19th century, and the classic experiments of Wohler were completed by 1870. An article on "Wohler's Experiments on the Strength of Metals" was published in 1867 in the 4th volume of Engineering, and a further lengthy report on "Wohler's Experi ments on the Fatigue of Metals" appeared in 1871 in the nth volume of Engineering. London, W.C.2. M. NEAL. Editorial Staff, Engineering. Bread-and-butter Airliners SINCE your space is valuable and long controversies usually are not I shall ask that you accept this as my final contribution to the "bread-and-butter airliners" correspondence. Mr. Dennis Powell (April 4th) was kind enough to answer my last effusion with so eloquent a case for the Pionair conversion of the C-47 that one might almost believe him to be on the staff of Scottish Aviation. I understand that is not so. But I must point out a few errors and omissions in his support of British replacements for DC-3S and Lodestars when he offers us a rebuilt American aircraft. It is true that B.E.A.C. is using the Pionair and packing 28 or 32 people into rather a confined space. They also increase the wing loading by putting the a.u.w. up to 28,000 lb as against the standard DC-3 weight of 25,200 lb. So the landing and take-off speeds rise. Perhaps Mr. Powell has not fully appreciated that speed increases are frequently impossible if existing bush fields are to be used. He also states that United Airlines, Capital Airlines and S.W.A. are using a similar conversion. I take leave to dispute that. Capital Airlines may be. T.W.A. (see American Aviation, March 3rd, 1952); are to dispose of their DC-3 fleet as the Martin 4-0-4S come in and United have started taking delivery of some 40 Convair 340s. This does not suggest any long-term DC-3 policy. E.A.A.C. may use, according to my latest letter from John Maspero, Commercial Superintendent of that Corporation, a con verted DC-3. But even Mr. Powell offers only an additional five years of service. E.A.A.C., as Mr. Powell obviously does not know, wanted to use Twin Bonanzas, but could not obtain dollars when it was found that a suitable aircraft could be bought with soft currency. As regards dollars in East Africa, I would just say this; American light aircraft can be seen there, in small numbers, because (as any private or commercial operator will tell Mr. Powell) there is no com parable British aeroplane that will stand the climate. Let these be no mistake: I do not condemn British manufacturers because I am anti-British. My criticisms are offered because I, in common with anyone else interested in our civil aviation, think it is an appalling thing that we have almost nothing available to fill the gaps that must soon occur. London, S.E.22. BASIL CLARKE. "Primary" and "Basic" I N that portion of H. F. King's article ("Military Aircraft of the World," April 4th) which deals with training aircraft he appears to confuse the use of the designations "primary" and "basic". In the R.A.F. the terms "elementary" and "advanced" gave way, after the last war, to "basic" and "applied," the latter terms being thought more suited to the actual functions of two training stages—the first teaching the basic principles of flying, and the second giving practical application to those principles. It had long been realized that the term "Elementary flying instructor" tended to imply that a man possessed a lesser degree of ability than did his opposite number the "advanced flying instruc tor" although, in fact, this was far from the truth. Psychologically, therefore, the word "basic" was a considerable improvement, and it is interesting to note that we now have basic flying-training schools which are civilian-operated and at which National Ser vice airmen are trained on Chipmunks or Tiger Moths to a syllabus varying only in detail from the old elementary course. The introduction of the word "basic" coincided with the arrival of the Percival Prentice in the Flying Training Schools and this aircraft, therefore, became the first R.A.F. basic trainer, to be followed now by its successor the Percival Provost. Both these aircraft are essentially ab initio trainers and require no prior type such as is suggested by Mr. King; neither is there any fundamental change in formula as between these two types with the exception of the dropping of the third seat in the case of the Provost. Addi tional power for better climb and to enable training to be carried out at a greater average height, and improved flying qualities, are merely logical developments of the original idea. The Provost is, in fact, a straightforward Prentice replacement. It is no mean achievement which has enabled the R.A.F. to continue to carry out its pre-wings training on two types despite the enormous advances made in operational aircraft, but it is clear that Mr. King's use of the word "primary" which has no place in R.A.F. aircraft designation, may well obscure the actual situation. Harpenden, Herts. A. N. KINGWILL. [The author writes : Mr. Kingwill's letter underlines the danger of expedient nomenclature. While it is true that the Chipmunk is termed by the R.A.F. a basic trainer, it also passes under the titles: "elementary," "primary," "ab initio" and "initial." On the other hand, the ancient Tiger Moth is claimed by its makers to have been the principal basic trainer of the British Commonwealth for the 1939-45 war. I am, nevertheless, grateful to Mr. Kingwill for putting this rather tiresome matter into perspective.—ED.1 IN BRIEF W/C. H. S. Preston, R.A.A.F., manager and secretary of the Newcastle Aero Club, N.S.W., Australia, very much wants to obtain a series of eight water-colour drawings by the late Stanley Orton Bradshaw; he also wants copies of the 24 sepia prints by the same artist, published in 1919. All of them are of British, French, and German aircraft of the 1914-18 war, ranging from the B.E.2C to the Fokker D.VII. They are wanted for the decoration of the Newcastle clubhouse, which, incidentally, houses what is claimed to be the biggest flying-club in the world.
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
