From df4e10402b38b1b5f6fbf29fa197e798d33a7e6b Mon Sep 17 00:00:00 2001
From: Bart <bart@vandelint.net>
Date: Fri, 12 Jun 2026 18:38:56 +0200
Subject: [PATCH 1/3] Split cd and cm

---
 src/panel.jl | 57 +++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 41 insertions(+), 16 deletions(-)

diff --git a/src/panel.jl b/src/panel.jl
index 966b448f..69973313 100644
--- a/src/panel.jl
+++ b/src/panel.jl
@@ -396,40 +396,65 @@ end
 
 
 """
-    calculate_cd_cm(panel::Panel, alpha::Float64)
+    calculate_cd(panel::Panel, alpha)
 
-Calculate drag and moment coefficients for given angle of attack.
+Calculate the drag coefficient for the given angle of attack.
 """
-function calculate_cd_cm(panel::Panel{Tp}, alpha::Ta) where {Tp, Ta}
+function calculate_cd(panel::Panel{Tp}, alpha::Ta) where {Tp, Ta}
     R = promote_type(Tp, Ta)
-    isnan(alpha) && return R(NaN), R(NaN)
+    isnan(alpha) && return R(NaN)
     if panel.aero_model == LEI_AIRFOIL_BREUKELS
-        cd = evalpoly(rad2deg(alpha), reverse(panel.cd_coeffs))
-        cm = evalpoly(rad2deg(alpha), reverse(panel.cm_coeffs))
         if abs(alpha) > (π/9)  # Outside ±20 degrees
-            cd = 2 * sin(alpha)^3
+            return R(2 * sin(alpha)^3)
         end
-        return R(cd), R(cm)
+        return R(evalpoly(rad2deg(alpha), reverse(panel.cd_coeffs)))
     elseif panel.aero_model == POLAR_VECTORS
         cd_interp = panel.cd_interp
-        cm_interp = panel.cm_interp
         cd_interp isa Union{I1, I2, I5} || throw(ArgumentError("cd_interp is not initialized for POLAR_VECTORS."))
-        cm_interp isa Union{I1, I2} || throw(ArgumentError("cm_interp is not initialized for POLAR_VECTORS."))
-        return R((cd_interp::Union{I1, I2, I5})(alpha)),
-               R((cm_interp::Union{I1, I2})(alpha))
+        return R((cd_interp::Union{I1, I2, I5})(alpha))
     elseif panel.aero_model == POLAR_MATRICES
         cd_interp = panel.cd_interp
-        cm_interp = panel.cm_interp
         cd_interp isa Union{I3, I4, I6} || throw(ArgumentError("cd_interp is not initialized for POLAR_MATRICES."))
+        return R((cd_interp::Union{I3, I4, I6})(alpha, panel.delta))
+    elseif !(panel.aero_model == INVISCID)
+        throw(ArgumentError("Unsupported aero model: $(panel.aero_model)"))
+    end
+    return zero(R)
+end
+
+"""
+    calculate_cm(panel::Panel, alpha)
+
+Calculate the pitching-moment coefficient for the given angle of attack.
+"""
+function calculate_cm(panel::Panel{Tp}, alpha::Ta) where {Tp, Ta}
+    R = promote_type(Tp, Ta)
+    isnan(alpha) && return R(NaN)
+    if panel.aero_model == LEI_AIRFOIL_BREUKELS
+        return R(evalpoly(rad2deg(alpha), reverse(panel.cm_coeffs)))
+    elseif panel.aero_model == POLAR_VECTORS
+        cm_interp = panel.cm_interp
+        cm_interp isa Union{I1, I2} || throw(ArgumentError("cm_interp is not initialized for POLAR_VECTORS."))
+        return R((cm_interp::Union{I1, I2})(alpha))
+    elseif panel.aero_model == POLAR_MATRICES
+        cm_interp = panel.cm_interp
         cm_interp isa Union{I3, I4} || throw(ArgumentError("cm_interp is not initialized for POLAR_MATRICES."))
-        return R((cd_interp::Union{I3, I4, I6})(alpha, panel.delta)),
-               R((cm_interp::Union{I3, I4})(alpha, panel.delta))
+        return R((cm_interp::Union{I3, I4})(alpha, panel.delta))
     elseif !(panel.aero_model == INVISCID)
         throw(ArgumentError("Unsupported aero model: $(panel.aero_model)"))
     end
-    return zero(R), zero(R)
+    return zero(R)
 end
 
+"""
+    calculate_cd_cm(panel::Panel, alpha)
+
+Calculate drag and moment coefficients for the given angle of attack
+([`calculate_cd`](@ref) and [`calculate_cm`](@ref)).
+"""
+calculate_cd_cm(panel::Panel{Tp}, alpha::Ta) where {Tp, Ta} =
+    (calculate_cd(panel, alpha), calculate_cm(panel, alpha))
+
 """
     calculate_filaments_for_plotting(panel::Panel)
 

From d45c3b1d52bf869a02554340cef26bd9faf7ea92 Mon Sep 17 00:00:00 2001
From: Bart <bart@vandelint.net>
Date: Fri, 12 Jun 2026 18:54:39 +0200
Subject: [PATCH 2/3] Fix ordering

---
 .github/workflows/CI.yml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index 39bcd98a..10ae5147 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -58,7 +58,7 @@ jobs:
       - uses: julia-actions/julia-buildpkg@v1
       - name: Install matplotlib
         if: runner.os == 'Linux'
-        run: sudo apt-get install -y python3-matplotlib
+        run: sudo apt-get update && sudo apt-get install -y python3-matplotlib
       - name: Build PyCall with system Python
         if: runner.os == 'Linux'
         run: julia -e 'ENV["PYTHON"]="python3"; using Pkg; Pkg.add("PyCall"); Pkg.build("PyCall")'
@@ -90,7 +90,7 @@ jobs:
     - uses: julia-actions/cache@v2
     - uses: julia-actions/julia-buildpkg@v1
     - name: Install matplotlib
-      run: sudo apt-get install -y python3-matplotlib
+      run: sudo apt-get update && sudo apt-get install -y python3-matplotlib
     - name: Build PyCall with system Python
       run: julia -e 'ENV["PYTHON"]="python3"; using Pkg; Pkg.add("PyCall"); Pkg.build("PyCall")'
     - uses: julia-actions/julia-runtest@v1

From 1424f5c7adcf0adff2c83c60346e4e2822494d71 Mon Sep 17 00:00:00 2001
From: Bart <bart@vandelint.net>
Date: Fri, 12 Jun 2026 22:08:46 +0200
Subject: [PATCH 3/3] Fix flaky test

---
 test/Aqua.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/Aqua.jl b/test/Aqua.jl
index f029a707..4ed9be3c 100644
--- a/test/Aqua.jl
+++ b/test/Aqua.jl
@@ -4,6 +4,6 @@ using Aqua, VortexStepMethod, Test
       VortexStepMethod;
       stale_deps=(ignore=[:Xfoil, :Timers, :PyCall],),
       deps_compat=(ignore=[:PyCall],),
-      persistent_tasks=()
+      persistent_tasks=false
     )
 end