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Aviation History
1946
1946 - 0044.PDF
FLIGHT JANUARY 3RD, 194O CORRESPONDENCE The Editor does not hold himsetj responsible jot the views expressed by correspondents. The names and addresses of the writers., not necessarily for publication, must in all cases accompany letters. SHOCK TACTICS FOR SHOCK WAVES Where Rochets Succeed, Can Jets be Far Behind ? INDICATOR'S "• aiticle " Shock Tactics for Shock Waves "in the December 6th issue of Flight sounds a very plausible warning, but, also from the point of view of a " semi- technical outsider," I would like to query his conclusions and invite further information from aerodynamic specialist readers. The suggestion that we are probably going the wrong way about "going over the hump," and that we are not likely to be able to do it without atomic propulsion, appears unlikely in view of the several promising supersonic winged rocket missiles developed by the Germans. Where rockets succeed, can jets be far behind? Is the air intake problem realty so serious as to render the jet unsuitable? Further, we hear that some of our own jet engine designers are working on the estimate that a thrust /projected area ratio of 1,500 lb./ft.3 is adequate for exceeding Mach 10, and that an engine.of 1,000 lb./ft.- is now in design. They believe that so far as propulsion is concerned, "it's in the bag," but that control and structure problems will require much more effort and experiment for their solution. I would like to ask readers who are expert in this field to provide us with more compressibility information, including an explanation of the abnormally large degree of aerofoil sweep- back on the German rocket missiles, which appears to be their only basically unorthodox feature. STRESSMAN. [The above letter was received after last week's issue had gone to press, and is not a reply to "ex-S.T.P.," who com- mented on " Stressman's " previous letter.—ED.] PRIVATE AIRCRAFT Two Distinct Types Needed OF all the articles and suggestions dealing with private air-craft, it is remarkable how few recognise the need for two distinct types, i.e., the touring aircraft and the sporting air- craft. Two current light types, the Auster and Messenger, are no doubt good aircraft for touring purposes, but they are not par- ticularly suitable for sporting flying. First and most impor- tant because their initial and maintenance costs, though perhaps reasonable for the aircraft themselves, are not attrac- tive when the prospective owner wishes mainly to fly solo and does not desire the upkeep of a three- or four-seater aircraft. The .second point is that, to get the most out of flying, an open cockpit seems desirable, or at least a sliding hood'of the tear-drop variety. Also, whereas the touring machine needs a cruising speed of 100 m.p.h. or over, the sporting aircraft is concerned mainly with staying up in the air! Within reason, the slower the cruising speed the better, for this will mean low fuel con- sumption and more hours flying for a given outlay. The requisite type obviously falls in the ultra-light class of machine. Why these aircraft have found only limited popu- larity is not clear, unless it is that too many have been care- lessly built by enthusiastic amateurs or flown by people who could not appreciate the flight limitations of low power, with consequent acciflents and an apparently poor safety record for anything below 40 h.p. What would not help to increase their numbers is that air- craft designers delight in solving problems which necessitate introducing much complex equipment, but when it comes to the reverse (simplicity and low cost) they are nowhere to be seen, The popular newspapers publicise the " everyman's " aircraft from time to time in the shape of the conventional high-wing cabin type, but knowledgeable comment would not take long to show that these same machines are very far from being "everyman's" where the costs are concerned. Very light types arc so few in numbers that they rarely if ever hit the headlines, and there might le reason to assume the public is ignorant of their existence. The few successful types which have appeared have often gone out of production for what seems no reason at all, cer- tainly not because of technical faults. A good example of this was the Carden-Baynes auxiliary sailplane. By all reports the characteristics of this machine were excellent, and the fact that it was primarily a sailplane meant that the cost could be kept low. The disadvantage of the sailplane proper is the need for the right type of country if it is to get a good send-off, otherwise towing must be used to give it height. This fact limits soaring to particular areas, and is the chief reason why the sport cannot achieve greater popularity. The Carden-Baynes machine overcame this by employing a small power unit, com- pletely retractible (propeller included), which could be used for the take-off and until a suitable altitude was reached. In spite of this ingenious feature very few machines were ever built. lo find where all the gremlins of lower power and cheap flying are hidden may not be an easy task, but the sooner they are dealt with, the sooner will we be able to explore this important section of private flying. DOUGLAS DEANS. , COCKPIT CLASSIFICATION A Compromise SuggestedW RITING as an ex-A.T.A. pilot with some experience oi stepping into strange aircraft, I venture to express my opinion on the merits and demerits of Fit. Lt. White's sugges- tions in the article on "Cockpit Classification" in your issue of December 13th. I am in complete agreement with his plea for "grouping." Since the bad old days the aircraft industry has progressively endeavoured to iron the kinks out of flying by the application of new aerodynamic principles and increased engine efficiency, and by the use of devices to increase the margin of safety. Inversely, however, with increased efficiency, greater wing loadings and faster landing speeds, the aircraft of to-day becomes, when misused, increasingly a lethal weapon, and the operation of it more complicated and requiring a higher degree of concentration. In considering cockpit layout, therefore, the chief object should be to endeavour to avoid dividing the pilot's attention during operations which require the maximum concentration— such as those involved in take-off and landing. This, I am convinced, can be helped by the standard grouping of the main engine instruments in the way in which the b.f. panel has already been standardised. Jt is, 1 think, quite hopeless to expect the aircraft industry to standardise layout to the extent of the pattern laid down by Fit. Lt. White. With the diversity of types, insurmountable difficulties would arise. If his colour theory were introduced, in .addition to the existing kaleidoscopic effect of twinkling lights and coloured devices, the result would be indescribably chaotic. A compromise might, however, be effected which, whik- making the pilot's lot a great deal easier, would not cause too much trouble to the manufacturer. On single-engined aircraft the following would be the ideal arrangement. The Sperry panel would be mounted slightly to the left <>i the facia board, while, mounted similarly on the right, wouii! be a standard grouping of the main engine instruments in the order of use, as below: — M.& S.Switch Boost" Gauge Oil pressure A.S.I.Oil temp. devolutioncounter Coolant (or cyl. hd.) temps. Gill(or rad.shutter switchMag. switches, starter button, booster coil. Assuming that the benevolent designer has been good enough io arrange his flap and undercarriage levers conveniently on the port side, so, correspondingly, should the indicators be 0% the extreme left of the panel, and not haphazardjy positicaaea The operating limits of the various types of engine vary through a wide range of tolerances—even in different marks. Thus an oil pressure of 50lb./sq. in. on a Merlin 30 would not excite undue comment, while the same reading on a Packard-engined Mustang IV would be the signal for an emer- gency landing. On most American aircraft lines are painted on the dials indicating the 'maximum, minimum and normal operating figures, and this could be incorporated on British instruments without any difficulty. This would at least obviate the frantic hunt for the data panel usually so cun- ningly concealed under the cockpit coaming. Auxiliary instru- ment positioning can be left to the designer's discretion. The hazards of high-speed approach are considerably in- creased by the need for ducking one's head to glance at the A.S.I. Some form of external and easily visible A.S.I, should be a standard fitting. (Continued on page 23)
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