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Revert "WIP: Airfoil fins normal force coefficient derivative calculation." #139

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Merged
giovaniceotto merged 1 commit into from
Feb 15, 2022
Merged

Revert "WIP: Airfoil fins normal force coefficient derivative calculation." #139

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Binary file removed docs/technical/aerodynamics/Fins_Lift_Coefficient.pdf
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19 changes: 11 additions & 8 deletions rocketpy/Rocket.py
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Original file line number Diff line number Diff line change
Expand Up @@ -534,7 +534,7 @@ def addFins(
distanceToCM,
radius=0,
cantAngle=0,
airfoil=False,
airfoil=None,
):
"""Create a fin set, storing its parameters as part of the
aerodynamicSurfaces list. Its parameters are the axial position
Expand Down Expand Up @@ -564,10 +564,11 @@ def addFins(
cantAngle : int, float, optional
Fins cant angle with respect to the rocket centerline. Must
be given in degrees.
airfoil : bool, optional
Fin's airfoil shape. If True, generic airfoil lift
calculations will be performed. If False, calculations for
the trapezoildal shape will be perfomed
airfoil : string
Fin's lift curve. It must be a .csv file. The .csv file shall
contain no headers and the first column must specify time in
seconds, while the second column specifies lift coefficient. Lift
coefficient is dimensionaless.

Returns
-------
Expand Down Expand Up @@ -710,7 +711,7 @@ def finNumCorrection(n):
"Cl",
)

else: # Calculate lift parameters for trapezoildal planar fins
else:

def cnalfa1(cn):
"""Calculates the normal force coefficient derivative of a 3D
Expand Down Expand Up @@ -741,15 +742,17 @@ def cnalfa1(cn):
)
return Cnalfa1

# Fin–body interference correction
clalpha *= 1 + radius / (s + radius)
# Import the lift curve as a function of lift values by attack angle
read = genfromtxt(airfoil, delimiter=",")

# Applies number of fins to lift coefficient data
data = [[cl[0], (n / 2) * cnalfa1(cl[1])] for cl in read]
cl = Function(
data,
"Alpha (rad)",
"Cl",
interpolation="linear",
extrapolation="natural",
)

# Takes an approximation to an angular coefficient
Expand Down