PROPELLER BLADE Russian patent published in 1994 - IPC

FIELD: aircraft engineering. SUBSTANCE: blade profiles near the root are formed by lower, upper and front flat planes which make sharp angles along the leading and trailing edges. The leading edge angle γ is equal to 45°, and the trailing edge angle b is 15°. The transition section from the upper to front surfaces is rounded and is made circular by radius r determined from incident flow velocity v and coefficient K which depends on the pressure drop rate on the roundness of the joint of the surfaces on the high-velocity side of the profile in the ratio r = vK. The upper and front surfaces converge as they move away from the root and are brought to zero at the end of the blade. Radius r increases lengthwise to the end of the blade forming at the end together with the lower surface a profile in the form of a segment with equal angles b at the leading and trailing edges. The blade trailing edges in plan deviate from the axis at an angle g and intersect at angle of 90°. The profile thickness increases to the root and the surfaces joint of the high-velocity surfaces of the profile has the form closer to triangular with an abrupt transition to the root rod. EFFECT: improved efficiency. 3 dwg