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README.md
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@@ -31,7 +31,7 @@ This document explains how the Python pipeline creates the **500 aircraft-style
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- On load, \\(x\\) is normalized to \\([0,1]\\); the perimeter is rotated so the first point is closest to the **trailing edge** \\(1,0\\) and the **upper surface** comes first.
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- **Polars (optional)**: QBlade/XFOIL exports with \\(\alpha, C_l, C_d, C_m\\).
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- Files are matched to airfoils by flexible filename heuristics.
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- Polars are parsed (3–4 numeric columns), **deduplicated in
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- **Random seed**: We use `np.random.default_rng(42)` so all 500 wings are reproducible bit-for-bit.
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---
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@@ -40,15 +40,15 @@ This document explains how the Python pipeline creates the **500 aircraft-style
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We generate **500** wings. Airfoils are cycled round-robin (≈50 wings per foil). For each wing we sample:
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- **Half-span**
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-
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- **Root chord** \\(c_{root}\\) (inches):
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-
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- **Taper ratio**
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-
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- **Twist endpoints (washout)** (degrees):
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-
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- The final twist distribution is **linear** from root to tip; then we **pin** the very first station to **
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We use **20 stations** (indices or 'slices') along the half-span:
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@@ -92,23 +92,23 @@ This yields the **Cho** vector (inches) over the 20 stations.
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## 4) Twist (Washout) Distribution
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With sampled endpoints
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$$
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\text{Twi}[j] = i_{\text{root}} + \big(i_{\text{tip}} - i_{\text{root}}\big)\frac{y_j}{s},\quad j=1..20.
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$$
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Then set
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---
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## 5) Lofting the 3D Wing for Previews
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Given the normalized perimeter
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1. Shift section to pivot origin:
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2. Scale to local chord
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3. Rotate by
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$$
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\begin{bmatrix} Y \\ Z \end{bmatrix}
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@@ -116,15 +116,15 @@ $$
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\begin{bmatrix} X_s \\ Y_s \end{bmatrix}.
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$$
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4. Spanwise coordinate for the whole perimeter at station
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The arrays
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---
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## 6) Planform Integrals & Derived Metrics
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Treat `Dis`/`Cho` as samples over the **half-span**
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- **Wing area** (full wing):
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@@ -134,7 +134,7 @@ S_{\tfrac{1}{2}} = \int_0^s c(y)\,dy \;\approx\; \operatorname{trapz}(\text{Dis}
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S_{\text{full}} = 2\,S_{\tfrac{1}{2}}.
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$$
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Convert:
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- **Mean Aerodynamic Chord** (full wing):
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@@ -145,17 +145,17 @@ $$
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We integrate on the half-span (inches), then convert MAC to meters.
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- **Aspect Ratio** (full span
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$$
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\text{AR} = \frac{b^2}{S_{\text{full (m}^2)}}.
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$$
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- **Polar-derived metrics** (if a polar is found):
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-
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-
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-
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- Small-angle lift slope and zero-lift angle (linear fit on
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$$
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C_l \approx m\,\alpha_\text{deg} + b
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## 8) Image Preview Column
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Each wing includes a 3D wireframe PNG (`render_png`) created from the lofted
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- Section loops at every station,
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- ~14 spanwise polylines to suggest the surface,
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- Isometric view (elev
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- Title string with span, root/tip chords, and taper.
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This renders directly in the Hugging Face Dataset viewer.
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@@ -196,7 +196,7 @@ This renders directly in the Hugging Face Dataset viewer.
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## 9) Why These Look Like Transport Wings
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- **Aspect ratio** typically in the 7–11 range (after area settles) due to sampled spans/cords.
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- **Taper**
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- **Quarter-chord pivot** is the standard torsion axis.
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- **Schrenk chord** smooths the planform compared to pure linear taper, approximating more elliptical loading.
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@@ -204,10 +204,10 @@ This renders directly in the Hugging Face Dataset viewer.
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## 10) Worked Example (Representative Draw)
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Let
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Twist endpoints:
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Mid-span chord
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$$
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c_{\text{trap}}(50) = 30 + (10.5-30)\cdot 0.5 = 20.25\text{ in},\quad
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c(50) \approx \tfrac{1}{2}(20.25+25.98) \approx 23.11\text{ in}.
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$$
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If
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$$
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\text{AR} = \frac{b^2}{S} \approx \frac{(5.08)^2}{3.226} \approx 8.0.
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$$
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MAC comes from the
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---
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## 11) What Makes Each of the 500 Unique?
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- **Airfoil choice** (≈50 samples per foil) → geometry & polar behavior differ.
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-
- **Planform**: each wing draws a new
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- **Twist**: each wing draws
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- **Performance summaries**: objective-style scores
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---
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- On load, \\(x\\) is normalized to \\([0,1]\\); the perimeter is rotated so the first point is closest to the **trailing edge** \\(1,0\\) and the **upper surface** comes first.
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- **Polars (optional)**: QBlade/XFOIL exports with \\(\alpha, C_l, C_d, C_m\\).
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- Files are matched to airfoils by flexible filename heuristics.
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+
- Polars are parsed (3–4 numeric columns), **deduplicated in \\(\alpha\\)**, and **sorted by \\(\alpha\\)**.
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- **Random seed**: We use `np.random.default_rng(42)` so all 500 wings are reproducible bit-for-bit.
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---
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We generate **500** wings. Airfoils are cycled round-robin (≈50 wings per foil). For each wing we sample:
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- **Half-span** \\(s\\) (inches):
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\\(s \sim \mathcal{U}[60,\;120]\\).
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- **Root chord** \\(c_{root}\\) (inches):
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\\(c_{\text{root}} \sim \mathcal{U}[18,\;36]\\).
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- **Taper ratio** \\(\lambda\\):
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\\(\lambda \sim \mathcal{U}[0.25,\;0.50]\\), so \\(c_{\text{tip}}=\lambda\,c_{\text{root}}\\).
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- **Twist endpoints (washout)** (degrees):
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\\(i_{\text{root}} \sim \mathcal{U}[0,\;2]\\), \\(i_{\text{tip}} \sim \mathcal{U}[-6,\;-2]\\).
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- The final twist distribution is **linear** from root to tip; then we **pin** the very first station to **\\(0^{\circ}\\)** so the wing “hinges” at the root plane (legacy convention).
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We use **20 stations** (indices or 'slices') along the half-span:
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## 4) Twist (Washout) Distribution
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With sampled endpoints \\(i_{\text{root}}\\) and \\(i_{\text{tip}}\\), define a **linear** twist:
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$$
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\text{Twi}[j] = i_{\text{root}} + \big(i_{\text{tip}} - i_{\text{root}}\big)\frac{y_j}{s},\quad j=1..20.
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$$
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Then set \\(\text{Twi}[1]=0^{\circ}\\) (root plane hinge).
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---
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## 5) Lofting the 3D Wing for Previews
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Given the normalized perimeter \\(\bar{x},\bar{y}\\) (TE→upper→LE→lower→TE), we scale and twist each section about the **quarter-chord** \\(x_{\text{pivot}}=0.25\\):
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1. Shift section to pivot origin: \\(x_c = \bar{x} - 0.25\\).
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2. Scale to local chord \\(c_j\\) (inches): \\(X_s = x_c\,c_j,\; Y_s = \bar{y}\,c_j\\).
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3. Rotate by \\(\theta_j=\text{Twi}[j]\cdot\pi/180\\):
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$$
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\begin{bmatrix} Y \\ Z \end{bmatrix}
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\begin{bmatrix} X_s \\ Y_s \end{bmatrix}.
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$$
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4. Spanwise coordinate for the whole perimeter at station \\(j\\): \\(S=y_j\\) (inches).
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The arrays \\(S, Y, Z\\) generate a fast **wireframe 3D PNG** used as the dataset’s `render_png` field.
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---
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## 6) Planform Integrals & Derived Metrics
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+
Treat `Dis`/`Cho` as samples over the **half-span** \\([0,s]\\) in **inches**. We integrate with the trapezoidal rule, then convert to SI for storage.
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- **Wing area** (full wing):
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S_{\text{full}} = 2\,S_{\tfrac{1}{2}}.
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$$
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Convert: \\(S_{\text{full (m}^2)} = S_{\text{full}}\cdot(0.0254)^2\\).
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- **Mean Aerodynamic Chord** (full wing):
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We integrate on the half-span (inches), then convert MAC to meters.
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+
- **Aspect Ratio** (full span \\(b=2s\cdot 0.0254\\) meters):
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$$
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\text{AR} = \frac{b^2}{S_{\text{full (m}^2)}}.
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$$
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- **Polar-derived metrics** (if a polar is found):
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- \\(C_{l,\max}=\max C_l\\) at \\(\alpha_{C_{l,\max}}\\).
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- \\(C_{d,\min}=\min C_d\\) at \\(\alpha_{C_{d,\min}}\\).
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- \\((L/D)_{\max} = \max(C_l/C_d)\\) at \\(\alpha_{(L/D)_{\max}}\\).
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- Small-angle lift slope and zero-lift angle (linear fit on \\(\alpha\in[-5^{\circ},5^{\circ}]\\)):
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$$
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C_l \approx m\,\alpha_\text{deg} + b
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## 8) Image Preview Column
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+
Each wing includes a 3D wireframe PNG (`render_png`) created from the lofted \\(S,Y,Z\\) arrays:
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- Section loops at every station,
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- ~14 spanwise polylines to suggest the surface,
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+
- Isometric view (elev \\(20^{\circ}\\), azim \\(35^{\circ}\\)),
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- Title string with span, root/tip chords, and taper.
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This renders directly in the Hugging Face Dataset viewer.
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## 9) Why These Look Like Transport Wings
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- **Aspect ratio** typically in the 7–11 range (after area settles) due to sampled spans/cords.
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- **Taper** \\(0.25\to 0.50\\) and **washout** \\(-6^{\circ}\to -2^{\circ}\\) are characteristic of transport wings aimed at cruise efficiency and benign stall.
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- **Quarter-chord pivot** is the standard torsion axis.
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- **Schrenk chord** smooths the planform compared to pure linear taper, approximating more elliptical loading.
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## 10) Worked Example (Representative Draw)
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Let \\(s=100\\) in, \\(c_{\text{root}}=30\\) in, \\(\lambda=0.35 \Rightarrow c_{\text{tip}}=10.5\\) in, stations=20.
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Twist endpoints: \\(i_{\text{root}}=1.0^{\circ}\\), \\(i_{\text{tip}}=-4.0^{\circ}\\), then \\(\text{Twi}[1]=0^{\circ}\\).
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Mid-span chord \\(y=50\\) in:
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$$
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c_{\text{trap}}(50) = 30 + (10.5-30)\cdot 0.5 = 20.25\text{ in},\quad
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c(50) \approx \tfrac{1}{2}(20.25+25.98) \approx 23.11\text{ in}.
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$$
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If \\(S_{\text{full}} \approx 5000\;\text{in}^2 \Rightarrow S_{\text{full}} \approx 3.226\;\text{m}^2\\) and full span \\(b=200\\) in \\(=5.08\\) m, then:
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$$
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\text{AR} = \frac{b^2}{S} \approx \frac{(5.08)^2}{3.226} \approx 8.0.
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$$
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MAC comes from the \\(c(y)^2\\) integral and is often in the \\(0.3\text{–}0.5\\) m range here.
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---
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## 11) What Makes Each of the 500 Unique?
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- **Airfoil choice** (≈50 samples per foil) → geometry & polar behavior differ.
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+
- **Planform**: each wing draws a new \\((s,\;c_{\text{root}},\;\lambda)\\) → different area, AR, MAC.
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- **Twist**: each wing draws \\(i_{\text{root}}, i_{\text{tip}}\\) → different load tendency.
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- **Performance summaries**: objective-style scores \\((\min C_d,\; \max C_l,\; \max C_l/C_d)\\) and the \\(\alpha\\) at which they occur differ per wing.
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---
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