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Aviation History
1928
1928 - 0316.PDF
SUTTLJEKXNT TO FLIGHT 30 APEIL 26, 1928 THE AIRCRAFT ENGINEER TABLE 1.—(A) Conventional Single-Bay Biplane : Parasitic Drag Synthesis. (Ref. Fig. 11 A) Component. Total : Body Wheels: Standard aero, 700 X 100 Struts: Front oleo and rear radius. Wires : tV-in. streamline... Wiring lugs and hinge joints Axle: 2-in. faired tube ... Total : Undercarriage Frontal Area (ft2-) 10-5 1-8 20 Drag Coeffi- cient (abs.) 0-20 015 Paras. Drag (lb. at) (lOOft.s.) 500 6-4 007 3-3 ... 009 0-20 0-4 ...(6atO-llb. each) 0-6 ... 1-1 006 1-6 Based on surface area Tail plane and elevators Fin and rudder Wires : 2 B.A. streamline Wiring lugs Tail skid 12-3 260 0005 31 0004 0-20 120 ..'. Oil ...(16 at 0-05 each) — (approx.) 11 0-5 0-8 1-2 Total : Tail 6-7 Centre-section struts : Front and 0-5 0-06 rear. Centre-section wires : Front, rear, 0-13 0-20 and side. Interplane struts : Front and rear 1-5 0-04 Incidence wires : J-in. streamline 0-13 0-20 Lift wires: |-in. streamline ... 0-45 0-20 Anti-lift wires : J-in. streamline 0-19 0-20 Wiring lugs ...(16atO-lib. each) 0-7 0-6 1-4 0-6 2-2 0-9 1-6 Total : Total : Wing bracing Miscellaneous fittings Total: Free air drag Interference drag factor ... (approx.) -j- 25 per cent. 8-0 30 80-0 200 Total: Parasitic drag 1000 Explanatory Notes. Total machine weight: 2,600 lb. Engine : 400-500 h.p. radial. Body : Rectangular frame, faired by contour stringers. Frontal area based on maximum cross-section of body. Drag coefficient includes body complete with radial cylinders, wind- screen, cockpit opening, etc. Undercarriage : Floating type with external oleo legs and standard aero-wheels. Unfaired hinge connections to body and axle. Tail: Wire braced type, top and bottom to two spars. Wing bracing: Single-bay truss with parasol centre- section. Panel (strut-cum-wire) type centre-section and interplane struts. Miscellaneous fittings : Includes external petrol piping, wing tank sumps, and various external accessories. Interference factor : Based on model and flight-test data. wing gap, but it cannot always be claimed as satisfactory from the pilot's viewpoint when bearing in mind the equally important problem of a clear forward view; often enough a good upward view is obtained only by sacrifice of reasonable landing requirements. Figs. 7-9 illustrate proposals for biplane fighters, keeping these two features, of smooth air flow and clear view, well to the fore as primary design conditions. Fig. 7 is a single- bay design, Fig. 8 a minor structural development of the same arrangement, and Fig. 9 a two-bay machine with divided chassis and a minimum of parasitic structure within the TABLE 2.—(B): " Clear-View " Single-Bay Biplane : Parasitic Drag Synthesis (Ref. Figs. 7 and 11-B) Frontal Drag Component Area Coeffi- cient (ft.2) (abs.) Total: Body 100 018 Wheels : Internally sprung, 700 X 2-0 0-12 100 Struts: Front and rear 1-7 0-06 Wires: ^-in. streamline ... ... 0-09 0-20 Wiring lugs ... ... ...(4at 0-05 lb. each) Axle : Aerofoil section (Surf, area) 10-0 0-005 Total : Undercarriage Tail plane and] _ . r 26-0 0-005 elevators Based on Fin and rudder J Surface area 1 12-0 0-004 Struts ... 0-33 0-06 Tail skid ... ... ... ... — (approx.) Total: Tail Paras. Drag (lb. at) (lOOft.s 42-8 5-7 2-4 0-4 0-2 1-2 9-9 31 11 0-5 10 5-7 Centre-Section Struts : " V " type 0-75 0 • 06 11 Interplane Struts : " V " type' ... 2-2 0-04 2-1 Lift wires : |-in. streamline ... 0-45 0-20 2-1 Anti-lift, wires : J-in. streamline 0-17 0-20 0-8 Wiring lugs (12 at 0-05lb. each) 0-6 Total : Wing bracing Total : Miscellaneous fittings Total : Free air drag Interference drag factor Total : parasitic drag 6- (approx.) 2-0 20 percent. 67-1 13-4 80- Explanatory Notes Total machine weight : 2,600 lbs. Engine : 400-500 h.p. radial. Body : Oval-section monocoque with extended (integral) wing roots. Frontal area based on maximum cross-section of body. Drag coefficient includes body complete with radial cylinders, windscreen, cockpit opening, etc. Undercarriage : Rigid type with internally-sprung wheels. Faired connections at bottom wing roots and wheel shields. Tail: Semi-cantilever type, single bottom struts only. Wing bracing : Single-bay truss with " Clear-view " centre- section. " V " type centre-section and interplane struts. Miscellaneous fittings : Includes various external acces- sories. Interference factor : Based on model data. airscrew disc. The undercarriage in each case incorporates internally sprung wheels and a rigid frame, faired at all connections—a subject to which we shall devote a few remarks in a later chapter. Fig. 11 has been drawn to compare the frontal aspect of the " clear-view " designs of Figs. 7 and 9 against a single-bay fighter on more orthodox lines, the respective drags being synthesised under Tables 1 to 3, and summarised in Table 4 for statistical comparison, along with the slipstream drags. Thus, in column (A), Table 4, the first sub-column indicates parasitic drag within the slip- stream, the second sub-column showing the total parasitic drags (i.e., both inside and outside the slipstream), as derived from Table 1. As all these figures are based on a machine of the same total weight and similar type of radial engine, the aerodynamic advantage of the " clear-view " arrangement is well brought out, the parasitic drag being reduced to about 77 to 80 per cent, of the conventional type. The corresponding effect upon performance will be discussed under Part II of these articles. Actually as they stand, there is little to choose, in totel 286&
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