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Aviation History
1946
1946 - 0783.PDF
APKIL I8TH, 1946 FLIGHT 403 CORRESPONDENCE the extra 10,000 lb, maintaining as far as possible angle of attack for maximum lift/drag ratio. The g.p.h. would in- crease due to the higher revs required, but we are not con- . cerned with g.p.h. as a.m.p.g. is the only indication of good range flying (ignoring winds) which would in this case be more favourable, for less time taken, than "B's" manner of flying as quoted by your correspondent. 4 DAVID W. HEARSEY. I [In fairness to "Mixture " he did not say that the procedure f: on which his problem was based was actually employed. As 5 we read it, the case was a hypothetical one to illustrate the point of the argument.—ED.] BOOSTING BRITISH AVIATION A New Organization Suggested pi.~: T SHOULD be grateful if you would allow me to suggest i- through the medium of your columns a new scheme for the furtherance of interest in British aviation. Such a scheme as I suggest would be organized from a central headquarters in London and would be aided by H.M. Govern- ment in its early stages if possible. Such a scheme would be known as the British Air League Movement. There would be three branches: the Aeronautical Branch, the Aircraft Recog- nition Branch and a Public Relations Branch. Each branch should be headed by an advisory council, as follows: • Aeronautical Advisory Council: Representatives of the Royal Aeronautical Society, Helicopter Society, Helicopter Association, and any other desirable experts. Aircraft Recognition Branch Advisory Council: An R.A.F. officer, an Army officer, a Naval officer, representatives of the A.T.C. and youth training corps, and any other desirable experts. Public Relations Council: Editors or representatives of Flight, Aeronautics, The Aeroplane, A.T.C. Gazette, Sailplane and Glider. A representative of Associated Press. A repre- sentative of the B.B.C. These councils would each possess a permanent secretary, and membership would be open to all without prejudice of any kind. Fees (including card and badge): Associates, 4s. 6d. p.a.; members 10s. p.a.; full members £1 p.a. and right to vote. Such a national organization would have many obvious bene- fits, and should be officially recognized. Any improvements? F. G. ISAAC. [Our correspondent may possibly have overlooked the exist- ence of the Air League of the British Empire.—ED.] •'#• REWARD FOR SERVICE The Lot of the Ex-Aircraft ApprenticeA GOOD deal has been heard in the Press recently about re-settlement, pensions, and the future conditions for the personnel of the armed forces. I crave your space to air thecase of the ex-aircraft apprentice who was commissioned during the war. Your readers will be familiar with their pre-war situation.They were recruited directly from secondary schools by com- petitive examination, with the promise of an attractive careerin the R.A.F. The baton of the Air Chief Marshal was to be -j»w hidden in one haversack, and in any case the training to be^received was to be such as to fit them for almost anything. Now the training was good, but somehow the eye of theneedle which led to the officers' mess was painfully narrow. There were cadetships, it is true, but how few; and thequalification was often more a matter of social and athletic suitability than of real merit. In any event, the competitionwas so fierce that only the really exceptional, who played some sport superbly, stood a chance even of consideration. When later, (after conquering the resentment in the ranksagainst the breed) the ex-apprentice applied for flying training, the competition was equally severe. Often six or more appear-ances before A.O.C.s were necessary, and even when the sanctum of the F.T.S. was breached, the slightest false stepwas sufficient for banishment for ever from the magic circle oi those who took the air. Imagine, then, the disillusion on meeting in the squadronthe " short-service " officer, in some cases a few who had failed the entry examination for apprentices some years before, butin all cases with no comparable experience. Imagine, too, the feelings of the ex-apprentice who mistooka " 5 " for a " 6 " on his medical, and later found his technical specialist officer a "G.D. star," thus achieving a permanentor medium appointment. Still, came the war, and the opportunity tor most of promo-tion beyond their dreams. In general, their competence was proved in the hardest cest of all, and they thonght that surelytheir services would be rewarded in the Peace. But the Peace is here, and the reward ? A few, a very veryfew, may be selected for~permanent commissions. Some may be offered the chance of postponing "the beach" lor a few-years by that incomparable snare and delusion the "extended service commission." The remainder—the great majority—can either choose a return to the Sgts.' Mess, or to cast their lot in "Civvy Street." Air Commodore Harvey has shownin the House the failure of the so-called '' Higher Appointments Committee." The average employer shows very rapidly whathe thinks of the "ex-regular," and, by way of illustration, points to his office boy who has returned a lieutenant-colonel. And when our ex-apprentice, desperate by this time, turnsto E.V.T., he finds he is barred from participation because he "has made the R.A.F. his career." What must they think of the recent correspondence in TheTimes anent the scaling-up of officers' pensions, when they con- sider their own £90 p.a. or so ? Truly, Sir, if asked to send their sons to the service of the King in similar conditions, might they not be forgiven if they remarked that the answer was to be found in " Pygmalion " ? "WING CO.," Rtd. KEEPING THEM RUNNING Power Losses In Gas Turbines AS one wno has had practical experience of gas turbinemaintenance, I would like to challenge some of Sqn. Ldr. Cracknell's statements made with regard to operational faultsand rectifications Flight, March 28th). For instance, the statement that, in the event of erraticoperation "it is customary to change either the throttle valve or A.C.U." needs qualification. Such a rule is bad mainten-ance practice as units should be changed only after logical elimination. In any case, a lot depends on the nature of the"erratic operation." If, as I understand it, the Squadron Leader means r.p.m. "hunting," then the A.C.U. can rarelygive rise to such a fault. The usual cause is a faulty fuel pump. A defective A.C.U. usually passes excessive quantitiesof fuel back to the tank, if of the barostat type, or else restricts pump delivery if of the B.P.C. type. The symptoms willrange from failure to obtain maximum r.p.m. to failure or difficulty to start, according to the type of A.C.U., and theexact nature cf the fault. The throttle valve rarely gives rise to "hunting' symptoms. The usual fault with this unit issticking and failure to answer to pilot's control, especially if the unit is of the cam-operated spring-return type. There seems little justification for a list of reasons for lossof power, as practically every defect can be placed under this heading. The first-named, low-burner pressure, is reallyan indication of some other trouble and will produce an effect similar to closing the throttle, i.e., a reduction of r.p.m. andnot merely reduction in jet pipe temperature as implied. The same remarks apply to choked burners. '' Aerodynamic breakdown of the turbine nozzle guidevanes " seems rather drastic. Certainly after prolonged running slight distortions do give rise to correspondingly slight powerlosses, but the term "breakdown" is misleading. Increase of the compressor casing clearances will have anadverse effect on the engine performance, but such distortion is not readily detectable and, short of complete overhaul,there is little that can be done to overcome it. on any particu- lar engine. Distortion of the propelling nozzle is almostunknown and will, if present, be so small as 1 ; to affect the performance. Jet pipe leaks, on the other hand, while not affecting per-formance may have a deleterious effect on the adjacent air- frame or wiring, and are important for this reason. Partially seized bearings as a cause of performance loss israther begging the question. While bearing failures are few and far between, such plain bearings as do fail generally giverise to increased rather than decreased clearance, leading to oil seal rubbing, reduced oil pressure and sharp rise in oiltemperature, leaks from the bearing sealing glands and, in extreme cases, to turbine or impeller fouling. A failed ball orroller bearing is even rarer, but in any case there is little or no time between the "free" and "seized" states. With regard to the causes of high jet-pipe temperatures, afault in the cooling air system will have but little effect on jet pipe temperature. The cooling air merely prevents heattransfer from the turbine disc to the rear bearing. R. E. T. HACK.
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