From 4baa99bcf568f91ffe9ce961e86185cf42a75a4b Mon Sep 17 00:00:00 2001
From: Marius Peter <blendoit@gmail.com>
Date: Sun, 9 Jun 2019 11:50:49 -0700
Subject: class Stringer

---
 creator.py | 16 ++++++----------
 main.py    | 12 +++++++++++-
 2 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/creator.py b/creator.py
index b1a58a9..953f088 100644
--- a/creator.py
+++ b/creator.py
@@ -236,7 +236,7 @@ class Airfoil(Coordinates):
 
 
 class Spar(Coordinates):
-    """Contains a single spar's location and material."""
+    """Contains a single spar's location."""
     global parent
 
     def __init__(self):
@@ -275,17 +275,13 @@ class Spar(Coordinates):
 
 
 class Stringer():
-    """Contains the coordinates of stringer(s) location and material."""
+    """Contains the coordinates of stringer(s)."""
+    global parent
 
     def __init__(self):
-        # Stringer attributes
-        self.stringer_x_u = []
-        self.stringer_y_u = []
-        self.stringer_x_l = []
-        self.stringer_y_l = []
-        self.stringer_mat = []
-
-    def add_stringers(self, *density):
+        super().__init__(parent.chord, parent.semi_span)
+
+    def add_stringer(self, *density):
         """
         Add stringers to the wing from their distribution density between spars.
         First half of density[] concerns stringer distribution on
diff --git a/main.py b/main.py
index f62a88a..4bbd7a9 100644
--- a/main.py
+++ b/main.py
@@ -38,6 +38,7 @@ def main():
         af.naca(2412)
         # Print coordinates of af to terminal
         af.print_coord(4)
+
         # Create spar instance
         af.spar = creator.Spar()
         # Define the spar coordinates
@@ -45,8 +46,17 @@ def main():
         af.spar.add_spar(af.coordinates, 0.55)
         # Print coordinates of af.spar to terminal
         af.spar.print_coord(4)
+
+        # Create stringer instance
+        af.stringer = creator.Stringer()
+        # Define the stringer coordinates
+        af.stringer.add_stringer(af.coordinates, 0.15)
+        af.stringer.add_stringer(af.coordinates, 0.55)
+        # Print coordinates of af.stringer to terminal
+        af.stringer.print_coord(4)
+
         # Plot components with matplotlib
-        creator.plot(af, af.spar)
+        creator.plot(af, af.spar, af.stringer)
 
         # Save component coordinates
         af.save_coord(SAVE_PATH)
-- 
cgit v1.2.3


From e5610a86d65615a91a89205b3ae4ee559a37d751 Mon Sep 17 00:00:00 2001
From: Marius Peter <blendoit@gmail.com>
Date: Sun, 9 Jun 2019 12:15:41 -0700
Subject: pack_coord method in Coordinates

---
 creator.py | 39 ++++++++++++++++++++++++++-------------
 main.py    | 33 ++++++++++++++++-----------------
 2 files changed, 42 insertions(+), 30 deletions(-)

diff --git a/creator.py b/creator.py
index 953f088..673cfe9 100644
--- a/creator.py
+++ b/creator.py
@@ -59,11 +59,12 @@ class Coordinates:
         self.x_l = []
         self.y_l = []
         # Coordinates x_u, y_u, x_l, y_l packed in single list
-        self.coordinates = []
+        self.coord = []
+        # The airfoil components know the Coordinates instance's coords
         global parent
         parent = self
 
-    def print_coord(self, round):
+    def print_component(self, round):
         """
         Print all the component's coordinates to the terminal.
 
@@ -100,6 +101,12 @@ class Coordinates:
         self.print_coord(4)
         return None
 
+    def pack_coord(self):
+        self.coord.append(self.x_u)
+        self.coord.append(self.y_u)
+        self.coord.append(self.x_l)
+        self.coord.append(self.y_l)
+
 
 class Airfoil(Coordinates):
     """This class enables the creation of a single NACA airfoil."""
@@ -227,11 +234,7 @@ class Airfoil(Coordinates):
             self.x_l.append(get_lower_coordinates(x)[0])
             self.y_l.append(get_lower_coordinates(x)[1])
 
-        self.coordinates.append(self.x_u)
-        self.coordinates.append(self.y_u)
-        self.coordinates.append(self.x_l)
-        self.coordinates.append(self.y_l)
-
+        super().pack_coord()
         return None
 
 
@@ -271,6 +274,8 @@ class Spar(Coordinates):
         self.y_u.append(y_u[spar_x_u])
         self.x_l.append(x_l[spar_x_l])
         self.y_l.append(y_l[spar_x_l])
+
+        super().pack_coord()
         return None
 
 
@@ -281,17 +286,25 @@ class Stringer():
     def __init__(self):
         super().__init__(parent.chord, parent.semi_span)
 
-    def add_stringer(self, *density):
+    def add_stringer(self, coordinates, den_u_1, den_u_2, den_l_1, den_l_2):
         """
-        Add stringers to the wing from their distribution density between spars.
-        First half of density[] concerns stringer distribution on
+        Add stringers to the wing from their density distribution.
 
         Parameters:
-        material: stringer material
-        *density:
+        den_u_1: upper nose stringer density (until first spar)
+        den_u_2: upper surface stringer density
+        den_l_1: lower nose stringer density (until first spar)
+        den_l_2: lower surface stringer density
 
+        Returns:
+        None
         """
-
+        # Airfoil surface coordinates
+        # unpacked from 'coordinates' (list of lists in 'Airfoil').
+        x_u = coordinates[0]
+        y_u = coordinates[1]
+        x_l = coordinates[2]
+        y_l = coordinates[3]
         # Find interval between leading edge and first upper stringer,
         # from density parameter den_u_1.
         interval = self.spar_x_u[0] / (den_u_1 * self.spar_x_u[0])
diff --git a/main.py b/main.py
index 4bbd7a9..bba67ce 100644
--- a/main.py
+++ b/main.py
@@ -19,7 +19,7 @@ import random
 import time
 start_time = time.time()
 
-CHORD_LENGTH = 100
+CHORD_LENGTH = 10
 SEMI_SPAN = 200
 
 POP_SIZE = 1
@@ -36,31 +36,30 @@ def main():
         af = creator.Airfoil()
         # Define NACA airfoil coordinates
         af.naca(2412)
-        # Print coordinates of af to terminal
-        af.print_coord(4)
+
+        print(af.coord)
 
         # Create spar instance
         af.spar = creator.Spar()
         # Define the spar coordinates
-        af.spar.add_spar(af.coordinates, 0.15)
-        af.spar.add_spar(af.coordinates, 0.55)
+        af.spar.add_spar(af.coord, 0.15)
+        af.spar.add_spar(af.coord, 0.55)
         # Print coordinates of af.spar to terminal
-        af.spar.print_coord(4)
 
-        # Create stringer instance
-        af.stringer = creator.Stringer()
-        # Define the stringer coordinates
-        af.stringer.add_stringer(af.coordinates, 0.15)
-        af.stringer.add_stringer(af.coordinates, 0.55)
-        # Print coordinates of af.stringer to terminal
-        af.stringer.print_coord(4)
+        # # Create stringer instance
+        # af.stringer = creator.Stringer()
+        # # Define the stringer coordinates
+        # af.stringer.add_stringer(af.coordinates, 0.15)
+        # af.stringer.add_stringer(af.coordinates, 0.55)
+        # # Print coordinates of af.stringer to terminal
+        # af.stringer.print_coord(4)
 
         # Plot components with matplotlib
-        creator.plot(af, af.spar, af.stringer)
+        creator.plot(af, af.spar)
 
-        # Save component coordinates
-        af.save_coord(SAVE_PATH)
-        af.spar.save_coord(SAVE_PATH)
+        # # Save component coordinates
+        # af.save_coord(SAVE_PATH)
+        # af.spar.save_coord(SAVE_PATH)
 
     # Print final execution time
     print("--- %s seconds ---" % (time.time() - start_time))
-- 
cgit v1.2.3


From 6e03a7184120cee7a4d3713936c97d64244c482a Mon Sep 17 00:00:00 2001
From: Marius Peter <blendoit@gmail.com>
Date: Mon, 10 Jun 2019 21:34:22 -0700
Subject: Stringer plotting & Coordinates __str__ method

---
 analysis.py          | 16 ---------
 creator.py           | 99 +++++++++++++++++++++++++++++++---------------------
 evaluator.py         | 16 +++++++++
 generator.py         | 16 +++++++++
 genetic_algorithm.py | 16 ---------
 main.py              | 34 +++++++++---------
 6 files changed, 108 insertions(+), 89 deletions(-)
 delete mode 100644 analysis.py
 create mode 100644 evaluator.py
 create mode 100644 generator.py
 delete mode 100644 genetic_algorithm.py

diff --git a/analysis.py b/analysis.py
deleted file mode 100644
index 8ea1579..0000000
--- a/analysis.py
+++ /dev/null
@@ -1,16 +0,0 @@
-# This file is part of Marius Peter's airfoil analysis package (this program).
-#
-# This program is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <https://www.gnu.org/licenses/>.
-
-import airfoil as af
diff --git a/creator.py b/creator.py
index 673cfe9..5ac4c06 100644
--- a/creator.py
+++ b/creator.py
@@ -64,14 +64,17 @@ class Coordinates:
         global parent
         parent = self
 
-    def print_component(self, round):
+    def __str__(self):
+        return type(self).__name__
+
+    def print_coord(self, round):
         """
         Print all the component's coordinates to the terminal.
 
         This function's output is piped to the 'save_coord' function below.
         """
         print('============================')
-        print('Component:', type(self).__name__)
+        print('Component:', str(self))
         print('Chord length:', self.chord)
         print('Semi-span:', self.semi_span)
         print('============================')
@@ -94,7 +97,8 @@ class Coordinates:
         """
         Save all the object's coordinates (must be full path).
         """
-        file_name = str(type(self).__name__)
+
+        file_name = str(self)
         full_path = os.path.join(save_dir_path, file_name + '.txt')
         file = open(full_path, 'w')
         sys.stdout = file
@@ -127,11 +131,11 @@ class Airfoil(Coordinates):
         # Theta
         self.theta = []
 
-    def naca(self, naca_num):
+    def add_naca(self, naca_num):
         """
-        This function generates geometry for our chosen NACA airfoil shape.\
-        The nested functions perform the required steps to generate geometry,\
-        and can be called to solve the geometry y-coordinate for any 'x' input.\
+        This function generates geometry for our chosen NACA airfoil shape.
+        The nested functions perform the required steps to generate geometry,
+        and can be called to solve the geometry y-coordinate for any 'x' input.
         Equation coefficients were retrieved from Wikipedia.org.
 
         Parameters:
@@ -245,7 +249,7 @@ class Spar(Coordinates):
     def __init__(self):
         super().__init__(parent.chord, parent.semi_span)
 
-    def add_spar(self, coordinates, spar_x):
+    def add(self, airfoil_coord, spar_x):
         """
         Add a single spar at the % chord location given to function.
 
@@ -258,11 +262,11 @@ class Spar(Coordinates):
         None
         """
         # Airfoil surface coordinates
-        # unpacked from 'coordinates' (list of lists in 'Airfoil').
-        x_u = coordinates[0]
-        y_u = coordinates[1]
-        x_l = coordinates[2]
-        y_l = coordinates[3]
+        # unpacked from 'coordinates' (list of lists in 'Coordinates').
+        x_u = airfoil_coord[0]
+        y_u = airfoil_coord[1]
+        x_l = airfoil_coord[2]
+        y_l = airfoil_coord[3]
         # Scaled spar location with regards to chord
         loc = spar_x * self.chord
         # bisect_left: returns index of first value in x_u > loc.
@@ -279,14 +283,15 @@ class Spar(Coordinates):
         return None
 
 
-class Stringer():
+class Stringer(Coordinates):
     """Contains the coordinates of stringer(s)."""
     global parent
 
     def __init__(self):
         super().__init__(parent.chord, parent.semi_span)
 
-    def add_stringer(self, coordinates, den_u_1, den_u_2, den_l_1, den_l_2):
+    def add(self, airfoil_coord, spar_coord, den_u_1, den_u_2, den_l_1,
+            den_l_2):
         """
         Add stringers to the wing from their density distribution.
 
@@ -299,41 +304,53 @@ class Stringer():
         Returns:
         None
         """
+
         # Airfoil surface coordinates
-        # unpacked from 'coordinates' (list of lists in 'Airfoil').
-        x_u = coordinates[0]
-        y_u = coordinates[1]
-        x_l = coordinates[2]
-        y_l = coordinates[3]
-        # Find interval between leading edge and first upper stringer,
+        # unpacked from 'coordinates' (list of lists in 'Coordinates').
+        airfoil_x_u = airfoil_coord[0]
+        airfoil_y_u = airfoil_coord[1]
+        airfoil_x_l = airfoil_coord[2]
+        airfoil_y_l = airfoil_coord[3]
+
+        # Spar coordinates
+        # unpacked from 'coordinates' (list of lists in 'Coordinates').
+        spar_x_u = spar_coord[0]
+        spar_y_u = spar_coord[1]
+        spar_x_l = spar_coord[2]
+        spar_y_l = spar_coord[3]
+
+        # Find distance between leading edge and first upper stringer,
         # from density parameter den_u_1.
-        interval = self.spar_x_u[0] / (den_u_1 * self.spar_x_u[0])
+        interval = den_u_1 * spar_x_u[0]
         # initialise first self.stringer_x_u at first interval.
         x = interval
         # Add upper stringers until first spar.
-        while x < self.spar_x_u[0]:
-            # Index of the first value of self.x_u > x
-            x_u = bi.bisect_left(self.x_u, x)
-            self.stringer_x_u.append(self.x_u[x_u])
-            self.stringer_y_u.append(self.y_u[x_u])
+        while x < spar_x_u[0]:
+            # Index of the first value of airfoil_x_u > x
+            index = bi.bisect_left(airfoil_x_u, x)
+            # Append the value of airfoil_x_u at index to stringer's coordinates
+            self.x_u.append(airfoil_x_u[index])
+            self.y_u.append(airfoil_y_u[index])
             x += interval
 
         # Find interval between leading edge and first lower stringer,
         # from density parameter den_l_1.
-        interval = self.spar_x_u[0] / (den_l_1 * self.spar_x_u[0])
+        interval = den_l_1 * spar_x_u[0]
         # initialise first self.stringer_x_l at first interval.
         x = interval
         # Add lower stringers until first spar.
-        while x < self.spar_x_l[0]:
+        while x < spar_x_l[0]:
             # Index of the first value of self.x_l > x
-            x_u = bi.bisect_left(self.x_l, x)
-            self.stringer_x_l.append(self.x_l[x_u])
-            self.stringer_y_l.append(self.y_l[x_u])
+            index = bi.bisect_left(airfoil_x_l, x)
+            self.x_u.append(airfoil_x_u[index])
+            self.y_u.append(airfoil_y_u[index])
             x += interval
+
+        super().pack_coord()
         return None
 
 
-def plot(airfoil, spar):
+def plot(airfoil, spar, stringer):
     """This function plots the elements passed as arguments."""
 
     print('Plotting airfoil.')
@@ -352,6 +369,7 @@ def plot(airfoil, spar):
     plt.plot(airfoil.x_u, airfoil.y_u, '', color='b', linewidth='1')
     # Plot lower surface
     plt.plot(airfoil.x_l, airfoil.y_l, '', color='b', linewidth='1')
+
     # Plot spars
     try:
         for _ in range(0, len(spar.x_u)):
@@ -361,14 +379,15 @@ def plot(airfoil, spar):
             plt.legend()
     except:
         print('Did not plot spars. Were they added?')
+
     # Plot stringers
-    # if len(self.spar_x) != 0:
-    #     for _ in range(0, len(self.stringer_x)):
-    #         x = (self.stringer_x[_], self.stringer_x[_])
-    #         y = (self.stringer_y_u[_], self.stringer_y_l[_])
-    #         plt.scatter(x, y, color='y', linewidth='1',
-    # else:
-    #     print('Unable to plot stringers. Were they created?')
+    try:
+        for _ in range(0, len(stringer.x_u)):
+            x = (spar.x_u[_], spar.x_l[_])
+            y = (spar.y_u[_], spar.y_l[_])
+    except:
+        print('Unable to plot stringers. Were they created?')
+
     # Graph formatting
     plt.gcf().set_size_inches(9, 2.2)
     plt.xlabel('X axis')
diff --git a/evaluator.py b/evaluator.py
new file mode 100644
index 0000000..6a87b7e
--- /dev/null
+++ b/evaluator.py
@@ -0,0 +1,16 @@
+# This file is part of Marius Peter's airfoil analysis package (this program).
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+import creator
diff --git a/generator.py b/generator.py
new file mode 100644
index 0000000..6a87b7e
--- /dev/null
+++ b/generator.py
@@ -0,0 +1,16 @@
+# This file is part of Marius Peter's airfoil analysis package (this program).
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+import creator
diff --git a/genetic_algorithm.py b/genetic_algorithm.py
deleted file mode 100644
index 8ea1579..0000000
--- a/genetic_algorithm.py
+++ /dev/null
@@ -1,16 +0,0 @@
-# This file is part of Marius Peter's airfoil analysis package (this program).
-#
-# This program is free software: you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <https://www.gnu.org/licenses/>.
-
-import airfoil as af
diff --git a/main.py b/main.py
index bba67ce..17d081a 100644
--- a/main.py
+++ b/main.py
@@ -13,13 +13,15 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
-import creator
+import creator  # Create geometry
+import evaluator  # Evaluate geometry
+import generator  # Iteratevely evaluate instances of geometry
 import random
 
 import time
 start_time = time.time()
 
-CHORD_LENGTH = 10
+CHORD_LENGTH = 40
 SEMI_SPAN = 200
 
 POP_SIZE = 1
@@ -27,7 +29,7 @@ SAVE_PATH = 'C:/Users/blend/github/UCLA_MAE_154B/save'
 
 
 def main():
-    # Create coordinate system specific to airfoil dimensions.
+    # Create coordinate system specific to our airfoil dimensions.
     creator.Coordinates(CHORD_LENGTH, SEMI_SPAN)
 
     # Interate through all wings in population.
@@ -35,27 +37,25 @@ def main():
         # Create airfoil instance
         af = creator.Airfoil()
         # Define NACA airfoil coordinates
-        af.naca(2412)
-
-        print(af.coord)
+        af.add_naca(2412)
 
         # Create spar instance
         af.spar = creator.Spar()
-        # Define the spar coordinates
-        af.spar.add_spar(af.coord, 0.15)
-        af.spar.add_spar(af.coord, 0.55)
+        # Define the spar coordinates, stored in single spar object
+        af.spar.add(af.coord, 0.15)
+        af.spar.add(af.coord, 0.55)
         # Print coordinates of af.spar to terminal
 
-        # # Create stringer instance
-        # af.stringer = creator.Stringer()
-        # # Define the stringer coordinates
-        # af.stringer.add_stringer(af.coordinates, 0.15)
-        # af.stringer.add_stringer(af.coordinates, 0.55)
-        # # Print coordinates of af.stringer to terminal
-        # af.stringer.print_coord(4)
+        # Create stringer instance
+        af.stringer = creator.Stringer()
+        # Define the stringer coordinates from airfoil's and spars'
+        af.stringer.add(af.coord, af.spar.coord, 0.2, 0.2, 0.2, 0.2)
+        # Print coordinates of af.stringer to terminal
+        # af.stringer.print_coord(2)
 
+        print(af.stringer.coord)
         # Plot components with matplotlib
-        creator.plot(af, af.spar)
+        creator.plot(af, af.spar, af.stringer)
 
         # # Save component coordinates
         # af.save_coord(SAVE_PATH)
-- 
cgit v1.2.3


From 8bbc799672b95d71ff80759c0f8bf30bc11f9c19 Mon Sep 17 00:00:00 2001
From: Marius Peter <blendoit@gmail.com>
Date: Tue, 11 Jun 2019 13:15:23 -0700
Subject: Final Stringer.add implementation

---
 creator.py | 105 ++++++++++++++++++++++++++++++++++---------------------------
 main.py    |  14 ++++-----
 2 files changed, 65 insertions(+), 54 deletions(-)

diff --git a/creator.py b/creator.py
index 5ac4c06..c6cae4e 100644
--- a/creator.py
+++ b/creator.py
@@ -78,19 +78,11 @@ class Coordinates:
         print('Chord length:', self.chord)
         print('Semi-span:', self.semi_span)
         print('============================')
-        print('x_u the upper x-coordinates:',
-              np.around(self.x_u, round),
-              sep='\n')
-        print('y_u the upper y-coordinates:',
-              np.around(self.y_u, round),
-              sep='\n')
-        print('x_l the lower x-coordinates:',
-              np.around(self.x_l, round),
-              sep='\n')
-        print('y_l the lower y-coordinates:',
-              np.around(self.y_l, round),
-              sep='\n')
-        print('\n')
+        print('x_u the upper x-coordinates:\n', np.around(self.x_u, round))
+        print('y_u the upper y-coordinates:\n', np.around(self.y_u, round))
+        print('x_l the lower x-coordinates:\n', np.around(self.x_l, round))
+        print('y_l the lower y-coordinates:\n', np.around(self.y_l, round))
+        # print('\n')
         return None
 
     def save_coord(self, save_dir_path):
@@ -140,7 +132,6 @@ class Airfoil(Coordinates):
 
         Parameters:
         naca_num: 4-digit NACA wing
-        chord: wing chord length, in any unit
 
         Return:
         None
@@ -284,22 +275,23 @@ class Spar(Coordinates):
 
 
 class Stringer(Coordinates):
-    """Contains the coordinates of stringer(s)."""
+    """Contains the coordinates of all stringers."""
     global parent
 
     def __init__(self):
         super().__init__(parent.chord, parent.semi_span)
 
-    def add(self, airfoil_coord, spar_coord, den_u_1, den_u_2, den_l_1,
-            den_l_2):
+    def add(self, airfoil_coord, spar_coord, stringer_u_1, stringer_u_2,
+            stringer_l_1, stringer_l_2):
         """
-        Add stringers to the wing from their density distribution.
+        Add equally distributed stringers to four airfoil locations
+        (upper nose, lower nose, upper surface, lower surface).
 
         Parameters:
-        den_u_1: upper nose stringer density (until first spar)
-        den_u_2: upper surface stringer density
-        den_l_1: lower nose stringer density (until first spar)
-        den_l_2: lower surface stringer density
+        stringer_u_1: upper nose number of stringers
+        stringer_u_2: upper surface number of stringers
+        stringer_l_1: lower nose number of stringers
+        stringer_l_2: lower surface number of stringers
 
         Returns:
         None
@@ -311,39 +303,51 @@ class Stringer(Coordinates):
         airfoil_y_u = airfoil_coord[1]
         airfoil_x_l = airfoil_coord[2]
         airfoil_y_l = airfoil_coord[3]
-
         # Spar coordinates
         # unpacked from 'coordinates' (list of lists in 'Coordinates').
-        spar_x_u = spar_coord[0]
-        spar_y_u = spar_coord[1]
-        spar_x_l = spar_coord[2]
-        spar_y_l = spar_coord[3]
-
-        # Find distance between leading edge and first upper stringer,
-        # from density parameter den_u_1.
-        interval = den_u_1 * spar_x_u[0]
-        # initialise first self.stringer_x_u at first interval.
+        try:
+            spar_x_u = spar_coord[0]
+            spar_y_u = spar_coord[1]
+            spar_x_l = spar_coord[2]
+            spar_y_l = spar_coord[3]
+        except:
+            print('Unable to initialize stringers. Were spars created?')
+        # Find distance between leading edge and first upper stringer
+        interval = spar_x_u[0] / (stringer_u_1 + 1)
+        # initialise first self.stringer_x_u at first interval
         x = interval
-        # Add upper stringers until first spar.
-        while x < spar_x_u[0]:
+        # Add upper stringers from leading edge until first spar.
+        for _ in range(0, stringer_u_1):
             # Index of the first value of airfoil_x_u > x
             index = bi.bisect_left(airfoil_x_u, x)
-            # Append the value of airfoil_x_u at index to stringer's coordinates
+            self.x_u.append(airfoil_x_u[index])
+            self.y_u.append(airfoil_y_u[index])
+            x += interval
+        # Add upper stringers from first spar until last spar
+        interval = (spar_x_u[-1] - spar_x_u[0]) / (stringer_u_2 + 1)
+        x = interval + spar_x_u[0]
+        for _ in range(0, stringer_u_2):
+            index = bi.bisect_left(airfoil_x_u, x)
             self.x_u.append(airfoil_x_u[index])
             self.y_u.append(airfoil_y_u[index])
             x += interval
 
-        # Find interval between leading edge and first lower stringer,
-        # from density parameter den_l_1.
-        interval = den_l_1 * spar_x_u[0]
-        # initialise first self.stringer_x_l at first interval.
+        # Find distance between leading edge and first lower stringer
+        interval = spar_x_l[0] / (stringer_l_1 + 1)
         x = interval
-        # Add lower stringers until first spar.
-        while x < spar_x_l[0]:
-            # Index of the first value of self.x_l > x
+        # Add lower stringers from leading edge until first spar.
+        for _ in range(0, stringer_l_1):
             index = bi.bisect_left(airfoil_x_l, x)
-            self.x_u.append(airfoil_x_u[index])
-            self.y_u.append(airfoil_y_u[index])
+            self.x_l.append(airfoil_x_l[index])
+            self.y_l.append(airfoil_y_l[index])
+            x += interval
+        # Add lower stringers from first spar until last spar
+        interval = (spar_x_l[-1] - spar_x_l[0]) / (stringer_l_2 + 1)
+        x = interval + spar_x_l[0]
+        for _ in range(0, stringer_l_2):
+            index = bi.bisect_left(airfoil_x_l, x)
+            self.x_l.append(airfoil_x_l[index])
+            self.y_l.append(airfoil_y_l[index])
             x += interval
 
         super().pack_coord()
@@ -375,16 +379,23 @@ def plot(airfoil, spar, stringer):
         for _ in range(0, len(spar.x_u)):
             x = (spar.x_u[_], spar.x_l[_])
             y = (spar.y_u[_], spar.y_l[_])
-            plt.plot(x, y, '.-', color='b', label='spar')
+            plt.plot(x, y, '.-', color='b')
             plt.legend()
     except:
         print('Did not plot spars. Were they added?')
 
     # Plot stringers
     try:
+        # Upper stringers
         for _ in range(0, len(stringer.x_u)):
-            x = (spar.x_u[_], spar.x_l[_])
-            y = (spar.y_u[_], spar.y_l[_])
+            x = stringer.x_u[_]
+            y = stringer.y_u[_]
+            plt.plot(x, y, '.', color='y')
+        # Lower stringers
+        for _ in range(0, len(stringer.x_l)):
+            x = stringer.x_l[_]
+            y = stringer.y_l[_]
+            plt.plot(x, y, '.', color='y')
     except:
         print('Unable to plot stringers. Were they created?')
 
diff --git a/main.py b/main.py
index 17d081a..909547e 100644
--- a/main.py
+++ b/main.py
@@ -21,7 +21,7 @@ import random
 import time
 start_time = time.time()
 
-CHORD_LENGTH = 40
+CHORD_LENGTH = 100
 SEMI_SPAN = 200
 
 POP_SIZE = 1
@@ -38,26 +38,26 @@ def main():
         af = creator.Airfoil()
         # Define NACA airfoil coordinates
         af.add_naca(2412)
+        af.print_coord(2)
 
         # Create spar instance
         af.spar = creator.Spar()
         # Define the spar coordinates, stored in single spar object
         af.spar.add(af.coord, 0.15)
         af.spar.add(af.coord, 0.55)
-        # Print coordinates of af.spar to terminal
+        af.spar.print_coord(2)
 
         # Create stringer instance
         af.stringer = creator.Stringer()
-        # Define the stringer coordinates from airfoil's and spars'
-        af.stringer.add(af.coord, af.spar.coord, 0.2, 0.2, 0.2, 0.2)
+        # Define the stringer coordinates from their amount
+        af.stringer.add(af.coord, af.spar.coord, 10, 7, 5, 6)
         # Print coordinates of af.stringer to terminal
-        # af.stringer.print_coord(2)
+        af.stringer.print_coord(2)
 
-        print(af.stringer.coord)
         # Plot components with matplotlib
         creator.plot(af, af.spar, af.stringer)
 
-        # # Save component coordinates
+        # Save component coordinates
         # af.save_coord(SAVE_PATH)
         # af.spar.save_coord(SAVE_PATH)
 
-- 
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