4/6/2023 0 Comments Reflexed airfoil![]() ![]() ![]() The method according to claim 1 further comprising:modifying the shape of the nacelle to meet the pressure constraint. The method according to claim 1 further comprising:redistributing the depth of the reflexed airfoil portion such that the reflex depth is at or below a desired wing thickness curve across at least a potion of the span of the wing. The method according to claim 1 further comprising:initializing computational fluid dynamics iterations with an approximate reflexed airfoil portion. The method according to claim 3 further comprising:adjusting the reflexed airfoil portion based on nacelle shock reflections. The method according to claim 1 further comprising:shifting the start of the reflexed airfoil portion in front of the inlet of the nacelle to reduce spillage of subsonic airflow in the inlet. An aircraft comprising:a wing with a non-movable reflexed airfoil portion, wherein: the reflexed airfoil portion includes a convergent section thickness of the underside of the wing that begins at an intermediate location between the leading edge and the trailing edge of the wing, and extends to the trailing edge of the wing, the shape of the convergent section thickness is defined by at least one reflex angle, and the slope of the at least one reflex angle is greater than or equal to zero proximate the trailing edge of the wing. Two digits describing the maximum thickness in percent of chord.The aircraft according to claim 9 wherein the wing includes an inboard gull dihedral portion.One digit describing the lift coefficient in tenths.One digit describing the distance of the minimum pressure area in tens of percent of chord.The 1-series airfoils are described by five digits in the following sequence: Prior to this, airfoil shapes were first created and then had their characteristics measured in a wind tunnel. In addition, for a more precise description of the airfoil all numbers can be presented as decimals.Ī new approach to airfoil design pioneered in the 1930s in which the airfoil shape was mathematically derived from the desired lift characteristics. One digit describing the distance of maximum thickness from the leading edge in tens of percent of the chord.įor example, the NACA 1234-05 is a NACA 1234 airfoil with a sharp leading edge and maximum thickness 50% of the chord (0.5 chords) from the leading edge.One digit describing the roundness of the leading edge with 0 being sharp, 6 being the same as the original airfoil, and larger values indicating a more rounded leading edge.The following table presents the various camber line profile coefficients:įour- and five-digit series airfoils can be modified with a two-digit code preceded by a hyphen in the following sequence: The formula for the shape of a NACA 00xx foil, with "xx" being replaced by the percentage of thickness to chord, is: y t = 5 t c, Plot of a NACA 0015 foil, generated from formula The 15 indicates that the airfoil has a 15% thickness to chord length ratio: it is 15% as thick as it is long.Įquation for a symmetrical 4-digit NACA airfoil The NACA 0015 airfoil is symmetrical, the 00 indicating that it has no camber. Four-digit series airfoils by default have maximum thickness at 30% of the chord (0.3 chords) from the leading edge. įor example, the NACA 2412 airfoil has a maximum camber of 2% located 40% (0.4 chords) from the leading edge with a maximum thickness of 12% of the chord. Last two digits describing maximum thickness of the airfoil as percent of the chord.Second digit describing the distance of maximum camber from the airfoil leading edge in tens of percents of the chord.First digit describing maximum camber as percentage of the chord.The NACA four-digit wing sections define the profile by: 1.2 Equation for a cambered 4-digit NACA airfoil.1.1 Equation for a symmetrical 4-digit NACA airfoil. ![]()
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