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Aviation History
1950
1950 - 0286.PDF
FLIGHT, 9 February 1950 (Left) Detail cf port intake, showing boundary-layer bleed. (Right) The effect of fuselage-waisting at wing intersection in straightening isobar endings. Dotted lines show the unwaisted condition. P.1052 . . . given value for M in the case of a conventional straight wing are changed when that wing is yawed at \f/ to d, cos*^ and CD costy at Mach number- r- The effect ofr " r cos f. sweep-back is, therefore, to increase (in the ratio of sec ^: 1) the Mach number at which given compressibility reactions occur. It must, however, be emphasized that the effects summarized are idealized and, strictly, are there- fore valid only for yawed wings of infinite span. In the far from ideal conditions of physical practice, the advan- tages to be gained by sweep-back are, perhaps, 50 per cent of those suggested by idealized theory. They are, never- theless, very well worth while and, in the Hawker case, show a handsome profit in limiting speed as between the straight-wing and swept-wing versions of the aircraft. The angle of sweep-back used for the 1052, namely, 35 deg at 0.25 chord, was an arbitrary choice decided upon as offering a reasonable compromise between the achieve- ment of a useful reduction of drag at high speed, and the maintenance of good handling qualities at low speed with- out the use of slots. In the event the gain in speed has been marked, whilst, astonishingly, the handling characteristics at low speed are virtually as good as those obtained with a straight wing. Aspect ratio was chosen in accordance with the results of an interesting study in which various aspect ratios were plotted against sweep-back for a whole family of wings. From these curves, a demarcation line could be drawn between optima and pessima and, as a result, the optimum aspect ratio for the particular angle of sweep-back selected for the 1052 was indicated—and it seems to work very well in practice. As in the case of the Sea Hawk, the centre-section stub wings are, to all intents and purposes, integral with the fuselage, but in the 1052 the nominal span of the stub wings has been reduced. This was brought about by the desirability of increasing the area of the wing proper as much as was practicably possible. In order, however, to maintain the requisite intake area, it was expedient to increase the intake root depth, and, in any case, this was facilitated by the greater depth of section incident upon the increased chord used, for the t/c ratio of the root at 13 per cent is the same as that of the Sea Hawk. This greater depth, in conjunction with the same fuselage, means that the contour of intersection between wing root and fuselage is considerably more curved in plan and, in fact, produces what can be likened to a "waisting." Aerodynamically, this effect is thought to offer some advantage, although quantitatively the magnitude of the effect is still largely a matter of conjecture. The reason- ing is that lines of constant pressure—isobars in meteoro- logical terms—can be plotted along the wing as a function of the flow velocities. In general, on a swept wing such as that of the 1052, these isobars run spanwise substantially parallel to the leading edge, but at the wing root tend to curve so as to meet the line of intersection with the fuselage at a right angle. The effect of fuselage waisting at the intersection is that the ends of the isobar curves are straightened somewhat: in other words, the induced velocities are lowered and, therefore, the effective drag is reduced. Although the thickness chord ratio of the 1052 wing is very nearly the same as that of the Sea Hawk, i.e., 10 per Centre-section showing stub-wing spars and fuselage frames. The rear fuselage is built upside down, the lower fin is integral.
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