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Aviation History
1967
1967 - 1672.PDF
262 FLIGHT International, 17 August 1967 PIPER TURBO NAVAJO in the'Air. . . The Navajo is a good-looking aircraft by any standards. A pre-production machine here flies over lonely Rockies scenery where its far-ranging name- sake Indian tribe may have roamed the way to FL200. At gross weight, full rated power and a speed of 110 m.p.h., an average climb rate of over l,200ft/min is claimed. The Navajo felt nicely stable in the climb, which even at 130 m.p.h. was at a modest attitude, and the noise level on the flight deck was not at all obtrusive. Having reached FL200, and settled on a north-westerly head- ing from Kidlington, I checked a few sample cruise settings. Seventy-five per cent power was tried first (2,400 r.p.m. and 33.5in manifold pressure) and a true airspeed of 250 m.p.h. was recorded—a figure 10 m.p.h. in excess of the claimed speed at gross weight. At 65 per cent power (2,400 r.p.m. and 28.4in), 236 m.p.h. was achieved (223 m.p.h. claimed), and 225 m.p.h. (204 m.p.h. claimed) at 55 per cent power (2,400 r.p.m. and 24.3in). Even allowing for the fact that the evaluation flight took place at nearly 1,0001b under gross, the lower power- setting cruise figures are considerably more than the claimed performance. Making a position-error allowance on the basis of the curve in the pilot's notes left no reason to doubt this fact. Although the American pilots' notes do not contain any reference to permitted maximum or manoeuvring speeds, the airspeed indicator of the demonstrator was green-lined to 210 m.p.h.—some 30 m.p.h. above the normal highest cruising speed. At all cruising speeds the Navajo was impressive for its easy gait; the controls gave a lively response for a moderate effort, and the harmony between the axes felt good. The trimmers are operated by sensibly sized wheels working in the proper axes and with clear position indicators. The elevator and aileron trimmers were powerful, but that for the rudder was slightly less effective for quickly getting the slip-ball central. A look at the low-speed characteristics started with a power- off clean stall (the gear warning light flashes as power is reduced and a warning horn sounds as speed falls off with the gear up). At about 80 m.p.h. indicated airspeed the stall- warning light—mounted above the attitude indicator—shone and at 70 m.p.h. the nose dropped, accompanied by slight air- frame buffet. In the same configuration, but in turning flight in either direction, the stall was accompanied by buffet and the aircraft rolled out straight. Lowering of the undercarriage and flaps at the high permitted speed of 150 m.p.h. was without significant trim change or transient forces. As the stall was approached with everything down, the warning light shone at an indicated 65 m.p.h. and the nose dropped at the very low airspeed of 60 m.p.h. On the several stalls I made in this configuration the wing dropped quite sharply to port and only by very carefully checking that the aircraft was flying absolutely straight (necessitating the application of a fair amount of rudder as the speed decayed) was it possible to do a stall without a significant wing-drop. In view of this unexpectedly skittish performance I did not feel inclined to try a stall off a turn in this configuration. The book recommends a normal approach speed of 95-105 m.p.h. according to weight, or 85-95 m.p.h. for a short landing technique, with full flap. The large powerful elevator was seen to have good power at the mid-c.g. position of the flight, and even at 85 m.p.h. the ailerons could induce a good rate of roll. A simulated full-power overshoot from a trimmed approach at 85 m.p.h. was easily held. With the aircraft trimmed in a full-power climb at the placarded minimum control speed of 85 m.p.h., the port engine was stopped unexpectedly for a check on the assymetric handling. The aircraft proved very controllable in this state, and nearly all foot load could be trimmed out. Only the unfortunate tendency to drop a wing at the all-down power-off stall is a blemish on an aeroplane that otherwise handles finely at all speeds. CANCELLED PROJECTS: THE LIST UP-DATED DETAILS of aircraft, engine and missile projects cancelled since 1951 were given by the Minister of Technology, Mr Wedgwood Benn, in a written Parliamentary answer on July 28. This latest list includes a figure of £2.5 million for the AFVG, cancelled last month, and £0.26 million for the P35, the "dynamic leap" vehicle on which British Aircraft Corporation made a project study. Estimated Project Cancelled Expenditure (£ million) Transport Aircraft Brabazon February 1952 6.45 Princess flying-boat May 1954 9.1 Vickers military transport December 1955 4.0 Rotodyne February 1962 13.65 HS68I February 1965 21.0 Operational Aircraft Developed Sturgeon anti-submarine aircraft March 1951 0.5 D.H. fighter May I9S2 2.5 Developed Hawker Hunter July 1953 0.14 Swift February 1955 22.0 Swift photo-reconnaissance fighter June 1955 0.3 Swift crescent-wing research fighter December 1955 1.6 Avro rocket intercepter September 1955 1.0 Thin-wing Javelin June 1956 2.3 Fairey supersonic fighter March 1957 0.15 Supersonic bomber (including engine) March 1957 2.05 Naval inttfeepter December 1957 3.2 P.I 154 February 1965 21.0 TSR.2 February 1965 195.0 AFVG July 1967 2.5 Project Engines Nomad Screamer Soar Turmo Big Gyron RB.I06 Orion turboprop Scorpion Spectre Super Sprite Missiles Guided bomb with television eye Vickers flying bomb Air-to-ship guided bomb Air-to-air missile with radar guidance Long-range surface-to-air guided weapon Heavy anti-tank missile Blue Steel Mk 2 Bloodhound 3 Blue Streak Low-level surface-to-air guided weapon Medium-range surface-to-surface missile Skybolt Swingfire Other Balloon-borne early-warning radar High-resolution reconnaissance radar Lightning 3 auto-attack system P35 aerial vehicle Expenditure figures have been extracted number of years and may noc all be on an idem lations, estimates have been given. Both sets approximate. Cancelled April 1955 March 1956 March 1965 March 1956 March 1957 March 1957 January 1958 February 1959 October I960 October I960 June 1954 September 1954 March 1956 June 1956 May 1957 September 1959 December 1959 March I960 April I960 December 1961 August 1962 December 1962 November 1964 Estimated Expenditure (£ million) 5.1 0.65 1.2 0.1 3.4 0.1 4.75 1.25 5.75 0.S5 3.1 0.7 0.9 7.5 1.5 2.4 0.825 0.6 84.0 0.8 32.1 27.0 0.234 1.3 0.73 1.4 0.26 November I960 February 1962 March 1965 October 1966 from records extending over » :ical basis. For more recent <;*««'• of figures should be
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