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Aviation History
1947
1947 - 0647.PDF
APRIL 24TH, 1947 FLIGHT 379 CORRESPONDENCE The Eddtf does not hold himself responsible for the views expressed by correspondents. The names and addresses of Ike writers. not necessarily for publication, must in all cases accompany Utters. MOBILE TEST BEDS Up to Take-off Speed ?I DISAGREE with your statement that the B.O.A.C. mobile engine test house allows '' the complete elimination of the need for air testing." Admirable and useful as it may be, it cannot prove such things as the adjustment of maximum r.p.m. at take-off or those elusive loss of power reports with all ground boost and rev readings spot on. ^l should not be forgotten that the engine is not " on load " e static, and unless the test house is mobile up to take-off speeds (happy thought), I for one wouldn't feel inclined to sign on the dotted line. P. FYFE MAURITZ. INFRA-RED Drawbacks to Use as Landing AidR EPLYING to your correspondent, H. J. Manners, in the issue of April 10th may I, as one who has worked on infra-red equipment through the war years, correct one or two misapprehensions that seem to be fairly general on this subject ? First, the work in this country in no way lagged behind that of Germany and America, though it had" little publicity. Secondly, the type of infra-red equipment referred to by Mr. Manners operates on the " near infra-red " ; that is, infra- red just beyond the visible spectrum, and in consequence has negligible fog penetrating qualities. Infra-red rays that will penetrate fog are confined to a fairlj- narrow waveband, and while instruments exist for their detection, in their present state of development they do not present the observer with a detailed extended visual image. Thirdly, the authorities in this country are fully aware of the potentialities, capabilities and, unfortunately, its very serious limitations as an aircraft landing aid. Finally, with present sources of infra-red radiation, the searchlight in the nose of the aircraft would have to be of enormous power and weight to give adequate range, and in any case the pilot would be completely dazzled by " back glare " due to reflection of a large proportion of the infra-red by the fog The suggestion of infra-red lamps on the runway, while not new by any means, is the more practical, but in any case it must await the further development, which promises to be very lengthy, of suitable long wavelength infra-red vision equipment. G. S. P. FREEMAN. AIRCRAFT LANDING Bad Weather Technique Advocated .'••"'-••-• AMONG the voluminous correspondence produced in the lastfew months on the subject of " Aircraft Safety," I consider that the letter in Flight of February 6th, 1947, by Graeme Percival, under the heading " Radio Beam Flying, a dangerous attitude of indifference," to be nearer the truth than any of the others, since ,the one basic fact on which all the others ^tepend is the mental attitude of the pilot. It has always been WrStruree of wonderment to me that while everything connected 'with an aircraft is stressed, constructed and tested with the ; . worst possible situation in mind, the pilot invariably, manoeuvres his aircraft to land by a technique which is entirely -i a fair-weather one. Moreover, his whole training is based on that fair-weather method, and his technique of arrival when the weather is bad is added almost as an afterthought. Some fifteen years ago the production of the standard instru- ment panel made two things possible. The first was that anybody could fly accurately instead of the few experts; and the other was that you could do it without looking out of the ; :. aircraft at all. The whole concept of pilotage changed, or •.-V; rather it should have done. Since then the development of bad-weather flying has been hindered by a retention of stan- dards which no longer mattered, by laziness, but above all by lack of decision. As a result of that retardation we are now faced with the problem of "landing capacity," a problem which would have solved itself by now if bad-weather flying had been developed in line with our progress in other respects. To add to our troubles we are now in the position of having so many aids that we are spoilt for choice, and we have no definite method for using any of them. Finally, the Press has exalted radar into being the logical successor to St. Christopher, and the public are confused and bewildeTed by the whole lazi- ness. And well they might be. The immediate step in the solution of this bad-weather flying problem, therefore, is to bring the pilotage of aircraft in line with design and adopt a technique oi landing which is gcart-J to the worst possible, and not to the favourable, conditions. The use of a circuit or approach by external observation must be forbidden when passengers are carried, and every approach must be made by instrument. Nothing less will do. It is an unfortunate fact that we cannot put on a different technique, as we do a mackintosh, when the weather is bad, and there are some melancholy facts which prove it, yet, as your corre- spondent points out, pilots avoid "pulling down the blinds" if it is at all possible and will persist in looking out. liven those that conscientiously do'their Link and IF. practices only resort to the use of them as a last resort. It seems to me then that there are two possibilities: — (1) The "Master" sits up at the front aud emulates the"Master" of a ship. Give him a telescope if you like to :ui't the right atmosphere. He can take the aircraft ofl and take itover to complete the landing when the approach has been made to tooft. Otherwise he does nothing but make decisions andthe aircraft is manoeuvred at all times by ;i "Coxswain" who is in a seat from which he can't look out, preferably soniewheiiin the bowels. He must have a full set of controls, "(.ciri^i" and an instrument panel. (2) The Captain flies the aircraft as he does now, except thatas he approaches the airfield he is screened. He is provided with a competent look-out whose sole duty is to avoid collisionswith uncontrolled aircraft and to " raise the biind" at 100ft on the approach. In each case I specify 100ft as the point to look up, for there won't be many occasions On which you can't land from then and this is not a paper on blind landings. It is to point out what I consider to be the least effective weapon in our armoury. I suppose the battle between civil aviation and the weather will finally be won bj' an automatic landing device, and such a thing is probably possible now, but I will guarantee it is ten years before it is marketable. Meanwhile the battle is on and we are losing it. G. E. LILLYWHITE (S/Ldr.). ROCKET ENGINES Fuel Mixing and Delivery WITH reference to the article on Rocket Engines, on pages•231 and 232 of Flight (March 20th), the line diagram shown in tiie top half of the illustration at bottom left of page 231 is misleading. This deals with the Walter M.W.K. 109-509 rocket engine fitted to the Messersohmitt Mei63is. Your diagram shows mixing of the C. Stoff and T. Stofl in the double walls of the combustion chamber. If this occurred in reality spontaneous combustion would occur with disastrous results to the combustion chamber. Also your line diagram shows the main distributor control valve as being interposed between the T. Stoff main supply and the double walls of the combustion chamber. The main distributor control valve is situated on the main C. Stoff supply lines to the combustion head. There is a secondary control valve- which is intercon- nected with the main control valve. This determines the quantity of T. Stoff being passed from the T. Mo/f pump delivery to the catalysts in the steam generator. As the main control valve is opened so is the secondary control valve and the supply of T. Stoff to the steam generator is increased. Tin- increase in available steam gives a greater rotational speed to the turbine wheel, greater delivery from the pumps, and so increased supply of the bi-fuels to the combustion head. Tin: diagram on the next page illustrates the layout. The T. Stoff consists of hydrogen peroxide 80 per cent and water 20 per cent. The C. Stoff consists of methanol (methvl alcohol) 57 per cent, hydrazine hydrate 30 per cent, and v.-.tie; 13 per cent. These mixtures are fed to their respective wimji- —the T. Stoff to the right-hand pump, and the C. Stoff to the left-hand pump. The C. Stoff passes to the double walk of the combustion chamber and acts as a coolant, thence back to the metering unit and through to the main distributor control valve. From here it passes directly to the combustion head through spray nozzles. The T. Stoff supply passes from its pump, to the metering unit (the pressure of the C. Stoif regulates the amount passed through this unit) and thence directly to the combustion head through sprf ••- •• • The C. Stoff and the T. Stoff intermingle at this j. . . i due f<,
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