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Aviation History
1949
1949 - 0078.PDF
FLIGHT JANUARY 1949 CORRESPONDENCE The Editor does not hold himself responsible for the views expressed by correspondents. The names and addresses of the writer* • ..-•.,.•-,.,.--•.• .,- not necessarily for publication, must in all cases.accompany letters. ••'"•••" V'i METEOR CLIMBS • '• ;':^/ ••.ir^',';i: ;•' Relative Performances with Derwent and Beryi MAY 1 correct a statement made in Flight of December 23 ?The error occurs in an article • giving comparative climb performances of the Meteor Mark 4 fitted with Rolls-Royce,Derwent V engines, and Meteor Mark 4 fitted with Metro-Vick Beryl engines. You state that the Derwent Meteor requires 8 min and ij_ minto climb to 30,000 and 40,000 feet respectively. At combat r.p.m., and with no external fuel tanks, thefigures for the Derwent Meteor are:— Time to Height ,•••'• 6.5 min 30,000ft" • _ •; - _J- 11.S min 40,000ft .••' '.'-• Hucclecote, Glos. .„ • E. S. GREENWOOD, . Technical Sales Manager. HELICOPTER HALOES .;;.:*•:•"" Robert Carting Taken to Task WITHOUT being goaded into anything, Casual Commentary(Flight, December 30th, 194$) does require an answer, but unfortunately to do justice would take too much of yourvaluable space. The article is a mixture of truth, half-truth and sheerbunkum, and it would be very interesting to meet Mr. Car- ling's so-called experts. In 26 years of flying, over 16 of whichhave been mainly on rotary-wing aircraft, I have never seen any haloes floating around, but almost certainly have heardvarious people "shooting their necks out" with insufficient knowledge of their subject. Finally, may I invite Mr. Carling to attend the next Heli-copter Association lecture on January 22nd at 2.30 p.m. at the Royal Aeronautical Society, when he wili have the oppor-tunity of meeting and talking to some who, like myself, are rotary-wing enthusiasts but by no means experts. Southampton. H. A. MAESH. ALTIMETER SETTINGS "Let the R.A.F. Play with Queenie Nan How" I HAVE read the paper on Altimeter Settings by W/C.Shelfoon in Flight of December 16th with interest and, may I add, with great disapproval. It is supposed to expound theargument in favour Of the QNH Setting and yet, in my opinion, fails to praduce a single factor in its favour and a considerablenumber against! It further introduces statements which are, to my mind,fallacious. An example of this is the statement that numbers of accidents due to collision with high ground have been-caused by the use of a QFE Setting. What proof has W/C. Shelfoon of this ? And why, if this is correct, were the pilotsconcerned flying on a QFE Setting and not on a Regional QFE, as they are supposed to do ? Apparently we are luckynot to have had some mid-air collisions due to some pilots flying Quadrantal Heights on a QFE and others on a RegionalQFF. W/C. Shelfoon states that a further reason in favour is toexpedite air traffic on cross-country flying and in the vicinity of an airfield and further to obviate last-minute alterations toAltimeter Settings before landing, and in the event of an over- shoot and subsequent diversion. I do not consider that thisargument will hold water, as all airline aircraft are at present using the Regional QFF and, therefore, have a common set-ting. Even if they used the QNH Setting this would have to be altered before landing at, say, London after a flight fromParis, as only in extremely abnormal .circumstances of pressure distribution would the QNH Setting be identical in both places.Therefore, in this respect, a QNH Setting has no advantage whatever over the present system. The writer goes on to say that reference to maps and ap-proach diagrams is necessary before attempting a blind let- down using a QFE Setting. I venture to state that very con-siderably more reference te maps, etc., will have to be made before starting a blind let-down using the QNH Setting, asthe captain, instead of remembering standard heights at Inner and Outer Markers (which are common to most S.B.A.systems) will have to check the airport height above Mean Sea Level and then add this to the approach heights, givingmore scope for mistakes, in that heights at Markers will be different at every airfield he goes to. Further, W/C. Shelfoon states that in the event,of a circuitbaying to be carried out under conditions of poor visibility, the QNH Setting is preferable to that of the QFE in respectof avoiding obstacles in the vicinity. I would suggest that this statement is at variance with the facts, and that only iil theevent of an airfield being below Mean Sea Level would the QNH be preferable. After all, if the airfield is, say, 200ft above Mean Sea Leveland you have a hill 500ft above Mean Sea Level in the vicinity, if your altimeter is set to QFE and you carry out a circuit atan indicated height of 500ft, you will clear the hill by 200ft. If you did the same thing with a QNH Setting, you would hitthe hill. I am not, of course, suggesting that any normal pilot would indulge in such close clearances. In any case, sofar as airline pilots are concerned, they do not operate to airfields in IFR conditions, unless they have been there beforeand practised the approved let-downs, and are familiar with any obstructions in the vicinity. As regards the " BABS " Approach system, I am not com-petent to pass any opinion, as I have never used it, but I note that even here complications arise and the navigator is calledupon to carry out the necessary calculations. In conclusion, it would appear that the QNH Setting hasbeen introduced for the benefit (sic) of the R..A.F. by the Air Ministry, and that M.C.A. have blindly followed suit, on theprinciple that what is good for the R.A.F. is good for Civil Aviation, which doctrine has been proved in many cases' tobe false. Leave us, therefore, our "Queenie Fox Easy" and let the K.A.F. play with their "Queenie Nan How" (AndHow !) "5O55-" Liverpool. 4, HOW BIG IS TOO BIG? C .4 Reply to Hilery Stanhope .<•' ' THE Woolworth Building, a profitable building, is' less thantwo-thirds the height of the Empire State Building, Radio City is just over two-thirds the height of the Empire State. ' Hence, the Empire State Building is about 50 per cent higherthan the Woolworth and R.C.A. Buildings. The largest ship just designed and ready for bids in U.S.A.is 48,000 tons. The Queens are 70 per cent larger than this. The Gold Standard and the law of "supply and demand"both have been discredited time and again in the last 7,000 years of our history, only the law of "diminishing returns" :has stood .the test of time. .".\ The big planes do not pay, but the smaller passenger planes 'do pay. STANLEY M. UDALE. Detroit, Mich., U.S.A. - WINDMILLS OR JETS? : "r . Thrust the Important Factor •»•" ' - '"THE interesting article by '' Favonius,'' which appeared-»- under the above title in Flight for December 30th, 1948, has inspired the following comments. An apology for theirobvious nature would be called for but for the fact that they are usually neglected in popular discussions on this theme;this seems especially true of certain statements which emanate periodically from airscrew specialists in the United States, whoseem particularly anxious to make their excellent products do a job for which they are not best fitted. The criterion of propulsive efficiency—or even overall(thermal x propulsive) efficiency—is a very important factor in determining power plant choice, but it is not the only one. Abetter guide is the quantity: (Power Plant Weight) + (Fuel Weight) for a given range atgiven speed and altitude. Obviously, the efficiency can affect only the term in thesecond bracket, and neglect of the first one obscures the very simple reason why jet propulsion is often the best choice, evenfor design conditions where it is less efficient than airscrew propulsion. Also relevant to these considerations is a funda- c 26
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