FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1964
1964 - 1567.PDF
868 FLIGHT International, 21 May 1964 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. Dichotomy in the Sixth SIR,—Your recent leader "Strengthening the Junior Wings" (April 30) prompts me to write this letter. 1 am most emphatically against the suggestion that the competition for the award should take the form of an essay. The sixth form in most schools is quite markedly split into "historians" and "scientists," the latter set being able to give much more to aviation. Would not the historians have the edge on us in the use of our language (English, not mathematics)? Surely it would be justifiable to award the sum to the pupil for outstanding flying aptitude, his parents' financial circumstances, and most important of all, his likelihood of making his career in the realms of aeronautics. Perhaps we shall be seeing company advertisements on the lines "fly on us now, work under us later"! Senior Sixth, STEPHEN G. HARRIS Queen Mary's Grammar School, Basingstoke, Hants Buffet Speeds SIR,—With reference to "Vx V2 and All That," Part 2, January 30, the definitions 3.1 and 3.2 for buffet speeds appear to be in error. Your contributor "CCJ" states correctly in the preceding discussion that "Low Buffet Speed would be encountered at successively higher altitudes and Mach numbers," i.e., that Vslb varies directly with altitude. In definition 3.1 he states that Vslb (CAS or Mach) "varies inversely with altitude." In fact it is Mach which varies, CAS remaining constant for an aircraft of a particular weight. Similarly, having correctly stated that High Buffet Speed is encountered at "decreasing ceiling with speed," i.e., lower Mach number with increase in altitude, his definition 3.2 states the opposite. West Ewell, Surrey M. H. SUTCLIFF Navigation Instructor, BEA Untrustworthy Spot Heights SIR,—Mr G. C. Scott's interesting article "Full of Sound- Signifying Nothing" in Flight International for April 30 prompts me to add to his views on flight safety having high priority, by drawing further attention to "Straight and Level" for. March 19 in which UK Notam 65-75/1964 is quoted thus: "Map SE 47/138, Edition 2: Change spot elevation 2,690ft at 44° 05'N 06° 45'E to 8,264ft." Roger Bacon remarked that he was glad this mistake had not killed anyone and of course I endorse that, but it does show that, as mountains do not grow in the night, a very serious state of affairs exists if spot heights on up-to-date maps can so easily be 5,574ft in error. When I first saw that Notam I felt that no other spot height could be trusted 100 per cent and it will be seen from the co-ordinates that this is not in the wilds of Siberia but in the vicinity of Nice. Brighton 7 PHILIP M. CRITCHLEY The Bigger Concord and the Sonic Boom SIR,—Although the recent changes in specification make the Concord project seem much more likely to be a commercial success, the sonic boom problem may be considerably more difficult to solve. Perhaps it is natural that BAC's statement (Flight International, May 7, p. 744) should be designed to allay any fears that the new gross weight might bring unacceptable intensities. But it is interesting to recall one recent public statement on this subject. Your December 19, 1963 issue reported Dr A. E. Russell, deputy technical director of the BAC-Sud Concord pro- gramme, when at the RAeS London Airport branch panel discussion, as speaking thus: "A supersonic airliner weighing 400,0001b, the sort of weight the Americans are talking about, will certainly produce unacceptable sonic booms ... 'I am certain of this,' said Dr Russell, 'because we are only just sure that our own weight [262,3501b] is not too great.'' " (my italics). But now, the weight has been increased by almost 25 per cent, to 326,0001b. BAC's statement notes that although the "volume effect" will be worse, this will be offset by the "lift effect," which will be less bad due to the lower wing loading. This raises the question—that I as an interested layman would naturally like answered—of whether in fact "lift effect" does not refer to the weight, but rather, refers to the wing loading? A situation which if taken to extremes seems somewhat surprising. Additionally, I find it difficult to reconcile the statement with certain basic facts given by Mr J. C. Floyd in the sixth Chadwick Memorial Lecture to the Manchester branch of the RAeS (see September 1961 issue of the Society's Journal). These are that (1) the lift effect is the dominant factor at high altitudes [i.e., the altitudes where the Concord will be going supersonic, presumably]; and (2) aircraft gross weight and altitude are the most powerful variables. Ipswich, Suffolk K. C. REAVELL Letting the Passengers Hear the Patter SIR,—Presumably Messrs Allen and Critchley (April 23 and May 7) would not expect to hear the air-to-ground com- munication in an emergency, so that should one develop, the broadcast would have to be abruptly switched off. This raises two points: first, that the passengers would realize something was amiss and become alarmed; secondly, that some member of the crew would have to spend some time (albeit a split second) in switching off—which might, in a sudden emergency, make all the difference between survival and non-survival. Leeds 2 R. M. SMITH Gasholder Landing System SIR,—When aircraft mistake Northolt for Heathrow and appear to a large extent to rely on visual reference to two correspondingly placed gasholders, surely the only remedy is colour? I suggest one gasholder white and the other red. By differential labelling, as you suggest in the May 7 issue, and when flying into the sun, difficulty could be experienced in ascertaining which is which, whereas by colouring they would be instantly recognizable and at a far greater distance. Loughton, Essex NOEL DUNMOW Engine Control in the Avro 5O4- SIR,—I was very interested to read Air Cdre Wheeler's reply (May 7) to my letter concerning the engine controls of the Avro 504K. The incompletely reported sentence in his lecture to the Kronfeld Club, now explained in his reply, is perfectly correct, and I agree it was possible to run a rotary engine slowly without using the "blip" switch, but one had to be an expert. Since quite a lot of juggling with the throttle and "fine adjustment" was required to hold the engine at a slow speed, the "blip" switch method of controlling engine speed was normally used by most pilots. Another correspondent, Sqn Ldr Horrox, in the same issue mentions the Monosoupape rotary engine. This engine, I believe, became obsolete in the Avro 504K because of its unreliability and the fact that it had only single ignition, whilst the Clerget and Le Rh6ne both had dual ignition and were more reliable engines. As regards the 504 with a Bristol Lucifer engine fitted, this was definitely a 504K, not a 504N, and was last seen by me at Southend aerodrome in 1936, when it called to refuel. Although the Clerget and Le RhSne-powered 504K air-
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
