Jerry
130 lines
4.3 KiB
OpenSCAD
130 lines
4.3 KiB
OpenSCAD
// Tapered Wing Section Parameters
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/* [Wing Geometry] */
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root_chord = 120; // [50:10:300]
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tip_chord = 80; // [30:10:200]
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span = 200; // [50:10:500]
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/* [NACA 4-Digit Profile] */
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// First digit (max camber in hundredths)
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naca_m = 0.02; // [0.00:0.01:0.09]
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// Second digit (position of max camber in tenths)
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naca_p = 0.40; // [0.10:0.10:0.90]
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// Last two digits (max thickness in hundredths)
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naca_t = 0.12; // [0.05:0.01:0.30]
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/* [Structural Features] */
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spar_radius = 4; // [1:0.5:10]
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lightening_holes = 5; // [0:1:10]
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/* [Appearance] */
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wing_color = "SteelBlue"; // [SteelBlue, Silver, Orange, White, DimGray]
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$fn = 64;
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// --- Mathematical Functions for NACA 4-Digit Airfoil ---
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function naca_camber(x, m, p) =
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(m == 0 || p == 0) ? 0 :
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(x < p) ? (m / pow(p,2)) * (2 * p * x - pow(x,2))
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: (m / pow(1-p,2)) * ((1 - 2*p) + 2 * p * x - pow(x,2));
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function naca_camber_deriv(x, m, p) =
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(m == 0 || p == 0) ? 0 :
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(x < p) ? (2 * m / pow(p,2)) * (p - x)
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: (2 * m / pow(1-p,2)) * (p - x);
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function naca_points(m, p, t, N=80) =
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let (
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upper = [for (i=[0:N])
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let (
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x = 0.5 * (1 - cos(i * 180 / N)),
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yt = 5 * t * (0.2969 * sqrt(max(0, x)) - 0.1260 * x - 0.3516 * pow(x,2) + 0.2843 * pow(x,3) - 0.1015 * pow(x,4)),
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yc = naca_camber(x, m, p),
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dyc = naca_camber_deriv(x, m, p),
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theta = atan(dyc)
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)
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[x - yt * sin(theta), yc + yt * cos(theta)]
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],
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lower = [for (i=[N-1:-1:1]) // Skip duplicate endpoints to form a closed loop
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let (
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x = 0.5 * (1 - cos(i * 180 / N)),
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yt = 5 * t * (0.2969 * sqrt(max(0, x)) - 0.1260 * x - 0.3516 * pow(x,2) + 0.2843 * pow(x,3) - 0.1015 * pow(x,4)),
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yc = naca_camber(x, m, p),
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dyc = naca_camber_deriv(x, m, p),
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theta = atan(dyc)
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)
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[x + yt * sin(theta), yc - yt * cos(theta)]
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]
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)
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concat(upper, lower);
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// --- Modules ---
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// Generates a rounded-end cylinder between two points, safely extended to cut cleanly
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module strut(p1, p2, r) {
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v = p2 - p1;
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ext = 5;
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dir = v / norm(v);
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p1_ext = p1 - dir * ext;
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p2_ext = p2 + dir * ext;
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hull() {
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translate(p1_ext) sphere(r=r);
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translate(p2_ext) sphere(r=r);
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}
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}
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// --- Main Geometry Assembly ---
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// Calculate standard spar locations (25% and 70% of chord length)
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x_spar1 = 0.25;
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x_spar2 = 0.70;
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// Calculate 3D coordinates for the spar tubes to correctly follow the camber and taper
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p1_root = [x_spar1 * root_chord, naca_camber(x_spar1, naca_m, naca_p) * root_chord, 0];
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p1_tip = [x_spar1 * tip_chord, naca_camber(x_spar1, naca_m, naca_p) * tip_chord, span];
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p2_root = [x_spar2 * root_chord, naca_camber(x_spar2, naca_m, naca_p) * root_chord, 0];
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p2_tip = [x_spar2 * tip_chord, naca_camber(x_spar2, naca_m, naca_p) * tip_chord, span];
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// Rotate wing to lay "flat" for standard viewing
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// (Span extends along +Y, chord along +X, thickness aligns with Z)
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color(wing_color)
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rotate([-90, 0, 0])
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difference() {
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// Solid Wing Shape
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linear_extrude(height = span, scale = tip_chord / root_chord)
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scale([root_chord, root_chord])
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polygon(naca_points(naca_m, naca_p, naca_t));
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// Spanwise Spar Tube Cuts
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strut(p1_root, p1_tip, spar_radius);
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strut(p2_root, p2_tip, spar_radius);
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// Lightening Hole Cuts (spaced evenly along span)
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if (lightening_holes > 0) {
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for (i = [1 : lightening_holes]) {
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let (
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// Space holes along the span
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z_pos = i * span / (lightening_holes + 1),
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// Determine the chord length at this spanwise position
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local_chord = root_chord + (tip_chord - root_chord) * (z_pos / span),
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// Position halfway between the two spars
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x_pos = 0.475 * local_chord,
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// Make the hole size proportional to the local chord length
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hole_r = local_chord * 0.12
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)
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// Cut through the airfoil thickness (Y axis in the unrotated frame)
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translate([x_pos, 0, z_pos])
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rotate([90, 0, 0])
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cylinder(h=root_chord * 2, r=hole_r, center=true);
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}
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}
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}
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