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Aviation History
1953
1953 - 0457.PDF
FLIGHT, 10 April 1953 453 THE WINNING TWO-SEATER . . . The rotary push-pull lateral-control linkage is carried in self-aligning bronze bearings, and has a rudi mentary universal joint at the dihe dral kink, off the right-hand side of the drawing. The cockpit is large and seats two abreast in comfort. The numbering is as follows: 1, throttle and mixture lev ers; 2, toe brakes; 3, rudder and nosewheel pushrods; 4, direct-vision panels; 5, oil tem perature and pressure; 6, engine r.p.m.; 7, A.S.I.; 8, compass; 9, fuel gauge; 10, turn and slip; 11, altimeter; 12, rate-of-climb; 13, gloves or radio; 14, second throttle; 15, fuel cock; 16, mop cose; 17, trim wheel; 18, flap lever; 19, parking brake and control lock. ECCENTRIC AND OUTER SLEEVE flap, 44 m.p.h.; take-off distance to 50ft in no wind, 325yd; landing distance over 50ft, 305yd; rate of climb at sea level with flaps at 20 deg, 757ft/min; rate of climb at sea level with flaps up, 845ft/min; service ceiling (iooft/min), 15,060ft; normal range against 20 m.p.h. wind at sea level, 296 miles; maximum range against 20 m.p.h. wind at sea level with 22 gal fuel (all-up weight 1,263 lb), 407 miles; still-air range with standard fuel, 360 miles; still-air range with 22 gal, 500 miles; maximum diving speed, 175 m.p.h. DETAILED COST ESTIMATE FOR 50 AIRCRAFT (PER AIRCRAFT) Item Spruce Plywood, 3/64in and 1/16in T.45 tubing T.4 tubing D.T.D. 610 sheet M.S. sheet ... Dural forging 1/8in Perspex sheet Price per Unit 433 per standard 1s 4d per sq ft — — £3 10s per cwt. — 12s per sq ft s. 5 5 5 9 4 15 d. 9 7 6 6 6 7; 0 par pound The above prices and Figures were used in calculating the costs below: tubes in the rear fuselage. These rubes, although left free enough to permit some sway and reduce friction, are restrained against bowing or sideways vibration capable of fracturing the end fittings. At the stern king-post the drive is led through a simple system of bell cranks and torque tubes. The basic philosophy underlying the control layout was, first, to provide large and efficient flaps and thereby permit some reduction in wing area (it is calculated that, with the N.A.C.A. flaps used, hinged to the lower wing surface, the wing has 4J per cent less area than would have been required if split flaps had been used) and, second, to provide control surfaces of the greatest possible area. Further gains have resulted from the empennage geometry, the vertical surface lying ahead of the elevators. No tabs are fitted anywhere, the trim wheel—just in front of the control column— being connected to a fore-and-aft spring bias. Costing.—It is rare indeed that any public discussion of aircraft costing can be undertaken. Although there appears to be little doubt that this was the item which gave competitors most trouble —similar aircraft were variously priced by different entrants be tween £600 and £4,000—we reproduce here much of the financial calculation carried out by the winning designers. Although the figures no doubt refer to Australian conditions, they appear to run fairly close to what might obtain in this country. MILLICER-BENNETT-TUTTY 2-SEAT DESIGN (One Blackburn Cirrus Minor de-rated to 75 b.h.p. Span, 25ft 8in; length, 21ft 6in; height, 6ft iiin; gross wing area, 117 sq ft. Weights: Empty, 682 lb; fuel and oil (16 and 1.45 gal), 128 lb; pilot, passenger and baggage, 410 lb; normal all-up weight, 1,220 lb. Control surface movements: Flaps (as flaps), 20 deg at take-off, 30 deg at landing; (as ailerons), +6 to —10 deg; ailerons (normal), +12 to — 20 deg; (drooped with flaps), 7 deg at take-off, n deg at landing; elevator, —25 to +14 deg; rudder, ±20 deg. Some aerodynamic constants: Profile-drag coefficient, 0.031; drag at looft/sec, 43 lb; maximum lift coefficient, 1.4 (flaps up) to 2.1 (flaps 35 deg); stick-force per f, 66 lb. General Performance Data: Performance at 1,220 lb with fixed-pitch airscrew: Maximum speed at sea level, 122 m.p.h.; maximum economical cruising speed at sea level on 60 b.h.p., 113 m.p.h.; stalling speed with engine off and flaps up, 54 m.p.h.; stalling speed with engine off and full Component Wing Front fuselage Centre fuselage ... Rear fuselage Tail unit ... Undercarriage Power plant installation Fabricated Weig it (lb) 123 15 93 47 32 35 17 362 Material Cost £ s. d. 20 6 0 7 8 0 50 3 0 12 0 0 6 3 0 52 10 0 394 0 0 542 1 0 Tooling Cost £ s. d. 61 0 0 15 0 0 46 10 0 23 10 0 16 0 0 35 0 0 17 0 0 214 0 0 No. of Man Hours 312 38 267 56 81 104 45 903 Labour costs ... Tooling for wood „ „ metal .. forgings... Wastage on material Profit 4s per hour f 250 per cent overheads. £25 per lb of fabricated structure. £50 „ „ £75 15 per cent on spruce, 30 per cent on plywood and sheet metal. 10 per cent on each aircraft. Complete costs per aircraft (when 50 made):— Material and accessories Tooling costs Labour ... Overheads (on labour costs) Profit Complete aircraft, fly away cost £ s. d. 542 10 0 214 0 0 180 10 0 452 10 0 139 0 0 . £1,528 10 0 If two prototypes included at £20/lb of fabricated weight, then the price changes to £1,760 per aircraft PRINCIPLES OF STRUCTURE "Structural Principles and Data," Vol. I of "Handbook of Aero nautics," 4th edition. Published by Sir Isaac Pitman and Sons, Ltd., Pitman House, Parker Street, London W.C.2. Price 45s. THE first edition of this standard work was published in 1931; the third edition (1937) appeared in three volumes, and the fourth edition—of which the first part is now available—is likely to run to at least eight. Published under the authority of the Council of the R.Ae.S., the handbook gained a deservedly high reputation before the late war. Complete revision and expansion was essential in the preparation of this fourth edition, and Structural Principles and Data shows this to have been thoroughly carried out. The contributors to this part are Walter Tye, J. H. Argyris and P. C. Dunne. The text is laid out in Stationery Office manner, undercarriage drag loads, for example, being discussed in Chap. 6, Sect. 5, Para. 2. Of the contents and presentation of the chapters we have no criticism, but we must express regret that a standard work should discard' 'angle of attack'' in favour of plain "incidence,'' particularly in these days of variable-incidence surfaces.
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