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@@ -31,7 +31,7 @@ This document explains how the Python pipeline creates the **500 aircraft-style
31
  - 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.
32
  - **Polars (optional)**: QBlade/XFOIL exports with \\(\alpha, C_l, C_d, C_m\\).
33
  - Files are matched to airfoils by flexible filename heuristics.
34
- - Polars are parsed (3–4 numeric columns), **deduplicated in $\alpha$**, and **sorted by $\alpha$**.
35
  - **Random seed**: We use `np.random.default_rng(42)` so all 500 wings are reproducible bit-for-bit.
36
 
37
  ---
@@ -40,15 +40,15 @@ This document explains how the Python pipeline creates the **500 aircraft-style
40
 
41
  We generate **500** wings. Airfoils are cycled round-robin (≈50 wings per foil). For each wing we sample:
42
 
43
- - **Half-span** $s$ (inches):
44
- $s \sim \mathcal{U}[60,\;120]$.
45
  - **Root chord** \\(c_{root}\\) (inches):
46
- $c_{\text{root}} \sim \mathcal{U}[18,\;36]$.
47
- - **Taper ratio** $\lambda$:
48
- $\lambda \sim \mathcal{U}[0.25,\;0.50]$, so $c_{\text{tip}}=\lambda\,c_{\text{root}}$.
49
  - **Twist endpoints (washout)** (degrees):
50
- $i_{\text{root}} \sim \mathcal{U}[0,\;2]$, $i_{\text{tip}} \sim \mathcal{U}[-6,\;-2]$.
51
- - 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).
52
 
53
  We use **20 stations** (indices or 'slices') along the half-span:
54
 
@@ -92,23 +92,23 @@ This yields the **Cho** vector (inches) over the 20 stations.
92
 
93
  ## 4) Twist (Washout) Distribution
94
 
95
- With sampled endpoints $i_{\text{root}}$ and $i_{\text{tip}}$, define a **linear** twist:
96
 
97
  $$
98
  \text{Twi}[j] = i_{\text{root}} + \big(i_{\text{tip}} - i_{\text{root}}\big)\frac{y_j}{s},\quad j=1..20.
99
  $$
100
 
101
- Then set $\text{Twi}[1]=0^{\circ}$ (root plane hinge).
102
 
103
  ---
104
 
105
  ## 5) Lofting the 3D Wing for Previews
106
 
107
- Given the normalized perimeter $(\bar{x},\bar{y})$ (TE→upper→LE→lower→TE), we scale and twist each section about the **quarter-chord** $x_{\text{pivot}}=0.25$:
108
 
109
- 1. Shift section to pivot origin: $x_c = \bar{x} - 0.25$.
110
- 2. Scale to local chord $c_j$ (inches): $X_s = x_c\,c_j,\; Y_s = \bar{y}\,c_j$.
111
- 3. Rotate by $\theta_j=\text{Twi}[j]\cdot\pi/180$:
112
 
113
  $$
114
  \begin{bmatrix} Y \\ Z \end{bmatrix}
@@ -116,15 +116,15 @@ $$
116
  \begin{bmatrix} X_s \\ Y_s \end{bmatrix}.
117
  $$
118
 
119
- 4. Spanwise coordinate for the whole perimeter at station $j$: $S=y_j$ (inches).
120
 
121
- The arrays $S, Y, Z$ generate a fast **wireframe 3D PNG** used as the dataset’s `render_png` field.
122
 
123
  ---
124
 
125
  ## 6) Planform Integrals & Derived Metrics
126
 
127
- 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.
128
 
129
  - **Wing area** (full wing):
130
 
@@ -134,7 +134,7 @@ S_{\tfrac{1}{2}} = \int_0^s c(y)\,dy \;\approx\; \operatorname{trapz}(\text{Dis}
134
  S_{\text{full}} = 2\,S_{\tfrac{1}{2}}.
135
  $$
136
 
137
- Convert: $S_{\text{full (m}^2)} = S_{\text{full}}\cdot(0.0254)^2$.
138
 
139
  - **Mean Aerodynamic Chord** (full wing):
140
 
@@ -145,17 +145,17 @@ $$
145
 
146
  We integrate on the half-span (inches), then convert MAC to meters.
147
 
148
- - **Aspect Ratio** (full span $b=2s\cdot 0.0254$ meters):
149
 
150
  $$
151
  \text{AR} = \frac{b^2}{S_{\text{full (m}^2)}}.
152
  $$
153
 
154
  - **Polar-derived metrics** (if a polar is found):
155
- - $C_{l,\max}=\max C_l$ at $\alpha_{C_{l,\max}}$.
156
- - $C_{d,\min}=\min C_d$ at $\alpha_{C_{d,\min}}$.
157
- - $(L/D)_{\max} = \max(C_l/C_d)$ at $\alpha_{(L/D)_{\max}}$.
158
- - Small-angle lift slope and zero-lift angle (linear fit on $\alpha\in[-5^{\circ},5^{\circ}]$):
159
 
160
  $$
161
  C_l \approx m\,\alpha_\text{deg} + b
@@ -183,10 +183,10 @@ If a polar is not found, these fields are **NaN**; geometry is still fully popul
183
 
184
  ## 8) Image Preview Column
185
 
186
- Each wing includes a 3D wireframe PNG (`render_png`) created from the lofted $S,Y,Z$ arrays:
187
  - Section loops at every station,
188
  - ~14 spanwise polylines to suggest the surface,
189
- - Isometric view (elev $20^{\circ}$, azim $35^{\circ}$),
190
  - Title string with span, root/tip chords, and taper.
191
 
192
  This renders directly in the Hugging Face Dataset viewer.
@@ -196,7 +196,7 @@ This renders directly in the Hugging Face Dataset viewer.
196
  ## 9) Why These Look Like Transport Wings
197
 
198
  - **Aspect ratio** typically in the 7–11 range (after area settles) due to sampled spans/cords.
199
- - **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.
200
  - **Quarter-chord pivot** is the standard torsion axis.
201
  - **Schrenk chord** smooths the planform compared to pure linear taper, approximating more elliptical loading.
202
 
@@ -204,10 +204,10 @@ This renders directly in the Hugging Face Dataset viewer.
204
 
205
  ## 10) Worked Example (Representative Draw)
206
 
207
- Let $s=100$ in, $c_{\text{root}}=30$ in, $\lambda=0.35 \Rightarrow c_{\text{tip}}=10.5$ in, stations=20.
208
- Twist endpoints: $i_{\text{root}}=1.0^{\circ}$, $i_{\text{tip}}=-4.0^{\circ}$, then $\text{Twi}[1]=0^{\circ}$.
209
 
210
- Mid-span chord $y=50$ in:
211
 
212
  $$
213
  c_{\text{trap}}(50) = 30 + (10.5-30)\cdot 0.5 = 20.25\text{ in},\quad
@@ -218,22 +218,22 @@ $$
218
  c(50) \approx \tfrac{1}{2}(20.25+25.98) \approx 23.11\text{ in}.
219
  $$
220
 
221
- 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:
222
 
223
  $$
224
  \text{AR} = \frac{b^2}{S} \approx \frac{(5.08)^2}{3.226} \approx 8.0.
225
  $$
226
 
227
- MAC comes from the $c(y)^2$ integral and is often in the $0.3\text{–}0.5$ m range here.
228
 
229
  ---
230
 
231
  ## 11) What Makes Each of the 500 Unique?
232
 
233
  - **Airfoil choice** (≈50 samples per foil) → geometry & polar behavior differ.
234
- - **Planform**: each wing draws a new $(s,\;c_{\text{root}},\;\lambda)$ → different area, AR, MAC.
235
- - **Twist**: each wing draws $(i_{\text{root}}, i_{\text{tip}})$ → different load tendency.
236
- - **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.
237
 
238
  ---
239
 
 
31
  - 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.
32
  - **Polars (optional)**: QBlade/XFOIL exports with \\(\alpha, C_l, C_d, C_m\\).
33
  - Files are matched to airfoils by flexible filename heuristics.
34
+ - Polars are parsed (3–4 numeric columns), **deduplicated in \\(\alpha\\)**, and **sorted by \\(\alpha\\)**.
35
  - **Random seed**: We use `np.random.default_rng(42)` so all 500 wings are reproducible bit-for-bit.
36
 
37
  ---
 
40
 
41
  We generate **500** wings. Airfoils are cycled round-robin (≈50 wings per foil). For each wing we sample:
42
 
43
+ - **Half-span** \\(s\\) (inches):
44
+ \\(s \sim \mathcal{U}[60,\;120]\\).
45
  - **Root chord** \\(c_{root}\\) (inches):
46
+ \\(c_{\text{root}} \sim \mathcal{U}[18,\;36]\\).
47
+ - **Taper ratio** \\(\lambda\\):
48
+ \\(\lambda \sim \mathcal{U}[0.25,\;0.50]\\), so \\(c_{\text{tip}}=\lambda\,c_{\text{root}}\\).
49
  - **Twist endpoints (washout)** (degrees):
50
+ \\(i_{\text{root}} \sim \mathcal{U}[0,\;2]\\), \\(i_{\text{tip}} \sim \mathcal{U}[-6,\;-2]\\).
51
+ - 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).
52
 
53
  We use **20 stations** (indices or 'slices') along the half-span:
54
 
 
92
 
93
  ## 4) Twist (Washout) Distribution
94
 
95
+ With sampled endpoints \\(i_{\text{root}}\\) and \\(i_{\text{tip}}\\), define a **linear** twist:
96
 
97
  $$
98
  \text{Twi}[j] = i_{\text{root}} + \big(i_{\text{tip}} - i_{\text{root}}\big)\frac{y_j}{s},\quad j=1..20.
99
  $$
100
 
101
+ Then set \\(\text{Twi}[1]=0^{\circ}\\) (root plane hinge).
102
 
103
  ---
104
 
105
  ## 5) Lofting the 3D Wing for Previews
106
 
107
+ 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\\):
108
 
109
+ 1. Shift section to pivot origin: \\(x_c = \bar{x} - 0.25\\).
110
+ 2. Scale to local chord \\(c_j\\) (inches): \\(X_s = x_c\,c_j,\; Y_s = \bar{y}\,c_j\\).
111
+ 3. Rotate by \\(\theta_j=\text{Twi}[j]\cdot\pi/180\\):
112
 
113
  $$
114
  \begin{bmatrix} Y \\ Z \end{bmatrix}
 
116
  \begin{bmatrix} X_s \\ Y_s \end{bmatrix}.
117
  $$
118
 
119
+ 4. Spanwise coordinate for the whole perimeter at station \\(j\\): \\(S=y_j\\) (inches).
120
 
121
+ The arrays \\(S, Y, Z\\) generate a fast **wireframe 3D PNG** used as the dataset’s `render_png` field.
122
 
123
  ---
124
 
125
  ## 6) Planform Integrals & Derived Metrics
126
 
127
+ 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.
128
 
129
  - **Wing area** (full wing):
130
 
 
134
  S_{\text{full}} = 2\,S_{\tfrac{1}{2}}.
135
  $$
136
 
137
+ Convert: \\(S_{\text{full (m}^2)} = S_{\text{full}}\cdot(0.0254)^2\\).
138
 
139
  - **Mean Aerodynamic Chord** (full wing):
140
 
 
145
 
146
  We integrate on the half-span (inches), then convert MAC to meters.
147
 
148
+ - **Aspect Ratio** (full span \\(b=2s\cdot 0.0254\\) meters):
149
 
150
  $$
151
  \text{AR} = \frac{b^2}{S_{\text{full (m}^2)}}.
152
  $$
153
 
154
  - **Polar-derived metrics** (if a polar is found):
155
+ - \\(C_{l,\max}=\max C_l\\) at \\(\alpha_{C_{l,\max}}\\).
156
+ - \\(C_{d,\min}=\min C_d\\) at \\(\alpha_{C_{d,\min}}\\).
157
+ - \\((L/D)_{\max} = \max(C_l/C_d)\\) at \\(\alpha_{(L/D)_{\max}}\\).
158
+ - Small-angle lift slope and zero-lift angle (linear fit on \\(\alpha\in[-5^{\circ},5^{\circ}]\\)):
159
 
160
  $$
161
  C_l \approx m\,\alpha_\text{deg} + b
 
183
 
184
  ## 8) Image Preview Column
185
 
186
+ Each wing includes a 3D wireframe PNG (`render_png`) created from the lofted \\(S,Y,Z\\) arrays:
187
  - Section loops at every station,
188
  - ~14 spanwise polylines to suggest the surface,
189
+ - Isometric view (elev \\(20^{\circ}\\), azim \\(35^{\circ}\\)),
190
  - Title string with span, root/tip chords, and taper.
191
 
192
  This renders directly in the Hugging Face Dataset viewer.
 
196
  ## 9) Why These Look Like Transport Wings
197
 
198
  - **Aspect ratio** typically in the 7–11 range (after area settles) due to sampled spans/cords.
199
+ - **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.
200
  - **Quarter-chord pivot** is the standard torsion axis.
201
  - **Schrenk chord** smooths the planform compared to pure linear taper, approximating more elliptical loading.
202
 
 
204
 
205
  ## 10) Worked Example (Representative Draw)
206
 
207
+ Let \\(s=100\\) in, \\(c_{\text{root}}=30\\) in, \\(\lambda=0.35 \Rightarrow c_{\text{tip}}=10.5\\) in, stations=20.
208
+ Twist endpoints: \\(i_{\text{root}}=1.0^{\circ}\\), \\(i_{\text{tip}}=-4.0^{\circ}\\), then \\(\text{Twi}[1]=0^{\circ}\\).
209
 
210
+ Mid-span chord \\(y=50\\) in:
211
 
212
  $$
213
  c_{\text{trap}}(50) = 30 + (10.5-30)\cdot 0.5 = 20.25\text{ in},\quad
 
218
  c(50) \approx \tfrac{1}{2}(20.25+25.98) \approx 23.11\text{ in}.
219
  $$
220
 
221
+ 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:
222
 
223
  $$
224
  \text{AR} = \frac{b^2}{S} \approx \frac{(5.08)^2}{3.226} \approx 8.0.
225
  $$
226
 
227
+ MAC comes from the \\(c(y)^2\\) integral and is often in the \\(0.3\text{–}0.5\\) m range here.
228
 
229
  ---
230
 
231
  ## 11) What Makes Each of the 500 Unique?
232
 
233
  - **Airfoil choice** (≈50 samples per foil) → geometry & polar behavior differ.
234
+ - **Planform**: each wing draws a new \\((s,\;c_{\text{root}},\;\lambda)\\) → different area, AR, MAC.
235
+ - **Twist**: each wing draws \\(i_{\text{root}}, i_{\text{tip}}\\) → different load tendency.
236
+ - **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.
237
 
238
  ---
239