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Aviation History
1964
1964 - 1852.PDF
fLIGHT International, IS June 1964 1027 Letters Letters for these columns are welcomed, though "Flight Inter- national" does not necessarily endorse the views expressed. Name and address should be given, not necessarily for publication in full. Brief letters will have a better chance of early publication. Stick-pusher Philosophy SIR,—I was pleased to be informed by M Satre (page 881, Flight International, May 28) of the apparently excellent stall qualities of all marks of Caravelle aircraft, and to be acquainted of the "pitch correction" system used to help obtain these results. It is regrettable that my original article in BALPA's The Log contained an inaccurate statement regarding this aircraft type. My source of information is obviously not as reliable as I had a right to believe. As you are aware, BALPA is considering the pros and cons of stick-pushers as fitted to Trident and VC10 aircraft, and we are obviously interested in all aircraft of similar configuration. It would be helpful to us in our deliberations if we had knowledge of the solutions adopted by different manufacturers when confronted with what must be similar problems on aircraft types so much alike as say, the Trident and Boeing 727. If the technical director/chief designer of the Boeing Airplane Company is also a reader of your columns he may perhaps wish to volunteer information as to whether con- sideration was ever given to fitment of a stick-pusher to the 727. Karachi L. TAYLOR [Captain L. Taylor is chairman of the technical committee of the British Air Line Pilots'1 Association.—Ed] Lord Brabazon ... SIR,—it is both right and inevitable that the subject of a memorial to the late Lord Brabazon of Tara be discussed, and ,one form it could take springs immediately to mind. This would be to recognize his work for air safety, and in particular his campaign for the use of kerosine in preference to JP.4, by prohibiting the use of the latter fuel by passenger- carrying aeroplanes serving this country. The Act should be known as the Brabazon Rules, and would in time come to be as widely revered, and perhaps as necessary, as the nautical Plimsoll line. This would not only provide a fitting and lasting tribute to his memory, but also one of which the Great Man would have surely approved. Trowbridge, Wilts JOHN c. SAWTELL ... and the Early Days SIR,—My friend Donald Chilton has written to me about my letter on Lord Brabazon's early flying (May 20): he has caught me napping on a number. It was the Bird of Passage which bore (in addition to its name) the designation "J. T. C Moore-Brabazon No 4." "J. T. C. Moore-Brabazon No 3" was on his first Voisin. He also raises the question of Brab's flight of 5km on January 17, 1909. My authorities for that date and distance are UAerophile, February 16, 1909 (page 86), and Dumas' Ceux qui ont vole (1909) page 87—both pretty good sources Your readers might like to know that there is a delightful photograph of Lady Brabazon sitting in the cockpit of The Bird of Passage reproduced full page in the Sphere for February 16, 1909. London SW7 CHARLES H. GIBBS-SMITH V,, V2 and All That SIR,—To tidy up the above series to date, I owe a letter to Mr P. C. H. White in reply to his two letters (February 20 and April 2) on Minimum Control Speeds and to Mr M. H. Sutcliff in reply to his letter (May 25) on the Buffet Speeds. I had better comment on these points before I get shot down on the half-dozen others to which the two numbers on the Decision Speed will probably give rise. The trouble I have in accepting all of Mr White's argument on Vmcg and VmCa is that, if one takes into account American concepts as well as British, it is difficult to ignore the fact that the American Vme is basically predicated on a maximum weight demonstration, whereas Mr White, looking at two British flight manuals, appears to have selected stalling speeds applicable to light weights. If one goes back to the US Civil Aeronautics Manual 4b 133-l(f), the demonstration of Vm<* must be made with:—• "Weight—maximum take-off. (If stall occurs prior to reaching Vme, applicant may choose to demonstrate a lower Vmc at a reduced weight.)" This certainly leads me to think that the American idea of Vmra is that it must always be demonstrable (i.e., not notional) and also must be greater than the power-on-stall. With regard to VmCg, I agree that this will frequently be greater than Vmca, this being due to the fact that, when demonstrating directional control on the ground, no gain can be made by dropping the wing 5° as is permitted for determining Vmca. Some aircraft will gain more from the 5° concession on Vmca and some will gain more from ground effect on the Vmcg demonstration. The upshot of these further considerations is that because, in its simplest concept, Vmc is related to the aerodynamics of the aircraft and does not have any direct connection with the stall, and because the stall itself is defined with power off while Vmc is demonstrated with power on, I believe that it would be preferable in the final definitions of Vmcg and Vmca to omit any reference to the stall. On the question of the Buffet Speeds, Mr M. H. Sutcliff is entirely right in that the Low Buffet Speed varies directly and the High Buffet Speed inversely with altitude, and the correction will be made in the "Final Definitions." It would also probably be better, in the definition of the Low Buffet Speed, to keep to Mach numbers and to omit any reference to Calibrated Airspeed. I was influenced to include Calibrated Airspeed by looking at the figure for the Boeing 320B (below) and by the desirability of talk- ing in the terms actually applied at low altitude, namely, A 224K/M6O HIGH BUFFET5PEEDS 3O4K NORMAL CRUISE MACH NORMAL 1g FLIGHT BOEING 32OB AT 27O,OOO Ib 15O 2OO 25O IAS 3OO 35O * The US procedures use the symbol Vmc to refer to a demonstration in the air—i.e., Vmca. Vmcg is not at present separately provided for in the US regulations.
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