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Aviation History
1960
1960 - 0050.PDF
50 FLIGHT, 8 January 1960 "Freedom Fighter"... the second deploys the aircraft at dispersed advanced bases withfixed pit-type launchers or portable zero-length launchers. Addi- tionally, the 156F can be operated from very short fields by usingfour 1,0001b JATO bottles for take-off and a "Liquid-Squeezer" arresting system; the latter cuts landing roll to only 1,000ft,and can accept up to four aircraft per minute. Use of these techniques allows of the maximum dispersion of the aircraft, andbrings to mind the methods used so successfully by the Luftwaffe in the closing months of World War 2. These make almost anystraight stretch of highway into an airfield, capable of being quickly adapted to suit varying situations. Such dispersed fieldsare difficult to put out of action, especially by unmanned missiles. Emphasis on low initial and recurring costs has resulted inmarked economy compared to other contemporary types, reflected in the number of aircraft that can be supported on a given budget. Correspondence The Editor of "Flight" is not necessarily in agreement with the viewsexpressed by correspondents in these columns. Names and addresses of writers, not for publication in detail, must in all cases accompany letters. , -f-FUSELACE OBJECT REFLECTED Mystery PictureR EGARDING the letter from• H. G. Cloete-Noding and • his puzzle picture (December 25issue): just in case he has not dis- covered it for himself already,the following should answer his questions. Referring to the diagram, focusis achieved by adjusting distance x in relation to distance d. Thewindow merely bends the shaded triangle, the length of whichremains the same. Your corre- spondent's picture could be aview forward and to starboard, showing the reflection of thegentleman in the front seat, or looking aft with reflection ofsomeone else in the back seat, port side. The dark area in the corner could be, respectively, the lower edge of the window frameor the wing trailing-edge. I will not reflect further on this subject, but just wish everyonea happy New Year. Flight through the letter box on the first day! A good start.St Albans, Herts JOHN P. BUTTERS Airline Safety I THINK that there must be a misprint in your article "AirlineFlight Safety," in the issue of December 25. You report Capt Miles as saying, "Detailing the area of flight in which the greatest danger could occur, the speaker mentioned the landing phase and the increasing number of overshoots. This came from the pilots' concern with overshooting on marginal-length run- ways." Surely the word "overshoots" is a misprint for "under- shoots"? [Not literally a misprint, but a transcription error— Ed.] If the above assumption is correct, Capt Miles is certainly invery good company in singling out the undershoot problem as an area of flight safety which at the present time needs the mosturgent reappraisal. In the United States, the United Kingdom and at ICAO we know that studies are afoot, but is the degree ofurgency fully recognized? In the UK some refinements have been added to the landing requirements for jet aircraft, but much stillremains to be done, especially in the wet-runway case. On an international basis, we are still using essentially the same formulafor the measurement of landing distance of jets as was used for the DC-3. But look at the new factors which have crept in: — (1) From the outer marker to the threshold a typical modern jet mustdissipate 32kt, calling for a deceleration of about 14kt/min; correspond- ing figures for the DC-3 are 15kt at 5kt/min. Clearly the jet pilot has amuch greater problem in arriving at the threshold at the correct speed. This will introduce a greater scatter of landing distances, therebyincreasing the tendency to overshoot and to undershoot. (2) The modern jet transport is a much heavier aeroplane, andapproaches faster, than the DC-3. Thus, during the flare-out, con- siderably high centripetal forces are induced. These temporarily putup the wing loading and the stalling speed, bringing the aeroplane nearer to the "mush" point—which tendency is typical of the class ofundershoot and heavy landing now occurring. A study was made of the anticipated funds that the NATO andSEAT countries would spend in support of the fighter mission between 1959 and 1965. It was assumed that two competitiveaircraft types would be supplied under the military assistance programme, this freeing the budget for operational costs only. Itwas found that the same amount of funds would be sufficient to procure and support 38 per cent more N-156Fs than one type and46 per cent more than the other. After making 32 flights with the original YJ85-1 engines thefirst airframe has been refitted with YJ85-5s. The second and third aircraft are due to fly this month and in March, respectively,and the third is fully representative of production aircraft in that it has full weapon-system capability. Now that the North American F-108 has been cancelled, thereader may be excused for thinking that the N-156F bids fair to be the last manned fighter to be designed in the USA. However,the Northrop Corporation is confident that it represents only the first of a new family of manned combat aircraft. (3) The clean design of the jet gives rise to a longer float than thepiston-engined aeroplane; so if it arrives at the threshold a little fast, the pilot cannot get it down so early on its wheels and is slower to initiateeffective braking. The result is a much greater penalty in landing dis- tances than the same error would produce in older aircraft. (4) The very great contribution of reverse thrust on the piston-enginedaeroplanes is, if it exists at all on the jet, very substantially reduced. (5) During an approach the application of power to the propeller-drivenaeroplane provides, by reason of slipstream effect, an almost instan- taneous increase (about lOkt) in the margin above stall. Conversely, thereduction of power immediately introduces a large propeller drag. These two effects together give the pilot a close control of speed. On the jet,however, an increase in power will not increase the margin above stall until the aeroplane's speed has had time to build up; and the reductionof power will introduce no braking effect. The above factors will combine to a greater or lesser extent onall jet landings and, as a result, the new jet pilot will find an almost inexplicable scatter in his landing distances—some of them(due to factors 1, 3, 4, and 5) tending to take him closer to the upwind end of the runway than is comfortable. To control thishe will subsequently endeavour to cut back his speed and height on the approach. But with this technique factor 5 can still beadverse; and with any speed reduction factor 2 raises its ugly head, occasionally perhaps devouring the whole of the safety margin.These effects can, of course, be minimized by very thorough train- ing, but they cannot be altogether eliminated. The result is anet increase in undershoots and heavy landings. London Wl C. C. JACKSON,Executive Secretary, International Federation of Air Line Pilots Associations "Flite" Readers' Corner DEAR pp. 909 thru 954.—Your informational product Flite(251'111'591'789-793) initiated our Christmas festivization at 0948 hr GMT X-day minus wun. Ace newshound EBN's out-standing uncovering of interesting picstories pp. 789, 790 and 792 earns gratitudinal approbation of all who believe in importance ofpublicization of cultural superiority of the Free World.—-Cordially, London Wl 771/3/8 I AM most anxious to join the staff of Flite and would like topoint out that I have special qualifications for Windmill assign- ments, having made a special study of helicopters. Please reservefor me the symposium delegate on the left (page 792) as my private secretary.Birmingham 14 MAURICE AUSTIN FORTHCOMING EVENTS Jon. 8. Helicopter Association: "The Development and FlightTesting of Helicopters/' by G. J. Sorsted and A. V. Coles. Jan. 9. British Interplanetary Society: Film Show.Jan. 12. Photogrammetric Society: "Small Scale Mapping," by Messrs. Wild Heerbrugg of Switzerland.Jan. 12. RAeS: 94th Anniversary Lunch. Jan. 13. Kronfeld Club: "National Aerobatic Contest," by Fit LtB. B. Sharman. Jan. 14. RAeS Astronautics and Guided Flight Section: "Future ofAutomatic Control on Fixed-wing Aircraft," by Prof G. A. Whitfield.Jan. 15. Denham Flying Club: First Annual Dinner. Jan. 15. RAeS (Agricultural Aviation Group): "Biological Factors inAgricultural Aviation," by C. V. Dadd. Jan. 15. Institute of Navigation: "Heading Definition in Commer-cial Aircraft," by J. Green and A. P. Glenny. Jan. 16. British Interplanetary Society: Schools Lecture, "TheScientific Exploration of Space," by Dr N. H. Langton. Jan. 19. RAeS: "Some Aerodynamic Problems of Engine Installa-tion/' by Dr J. Seddon. Jan. 20. Kronfeld Club: "Some experiences of Flying from 1914Onwards," by R. M. Charley. RAeS Branch Fixtures (to Jan. 15): Jan. 13, Chester, "Parachutes andParachute Design," by S. B. Jackson. Jan. 15, Preston, Annual Dinner and Danre.
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