AERODYNAMIC PROFILE OF LOAD-BEARING MEMBER OF FLYING VEHICLE Russian patent published in 1997 - IPC

FIELD: manufacture of helicopters; manufacture of blades for main and steering rotors. SUBSTANCE: upper portion of profile contour has front convex section with smoothly and monotonically increasing (from leading edge to center portion of profile) curvature radius and rear concave section with monotonically diminishing (towards trailing edge) curvature radius; both sections are coupled without break in curvature of contour by 80 percent of profile chord. Rounding-off radius of upper portion of leading edge of profile is equal to 2.3-2.8% of its chord; within range X=0.33 B-0.37 B magnitude Y_up reaches its maximum Y_upmax=0.0850 B-0.086B and curvature radius of contour R_up= 1.6 B-1.8 B, where B is profile chord; X is distance from leading edge along chord of profile; Y_up is distance from chord of profile along normal to it upward to upper part of contour; curvature radius R in concave portion of upper surface of contour profile smoothly reduces from X= 0.77 B-0.83 B to X=B and at trailing edge of profile R_up=0.7B-0.9 B and angle between tangent line to upper part of contour and chord of profile at X=B ranges from 3.6 to 6 deg. Leading edge of lower surface of profile is rounded off at curvature radius of R_low=0.006 B-0.0085 B over lower part of contour. Distance Y_low between chord of profile and its lower surface smoothly increases from nose rounding-off to its maximum Y_lowmax=0.022 B-0.024 B at X=0.4-0.65 B. Curvature radius of lower part of contour reaches it maximum in this zone and then smoothly decreases to 1.0 B-1.2B at X=B; angle between tangent line to lower part of profile contour at trailing edge and profile chord is equal to 8-10 dwg; thickness of trailing edge of profile is t < 0,01B.. Profile may be provided with special tail plate fitted on its trailing edge; length and incidence ar stipulated by required moment characteristics of profile. Variations of relative thickness of profile are probable due to proportional tension (compression) over normal to chord; proportionality factors may be different for upper and lower surfaces. EFFECT: enhanced reliability. 4 cl, 6 dwg, 1 tbl