from rocketpy.mathutils import Function
from rocketpy.plots.aero_surface_plots import _LinearGenericSurfacePlots
from rocketpy.prints.aero_surface_prints import _LinearGenericSurfacePrints
from rocketpy.rocket.aero_surface.generic_surface import GenericSurface
[docs]
class LinearGenericSurface(GenericSurface):
"""Class that defines a generic linear aerodynamic surface. This class is
used to define aerodynamic surfaces that have aerodynamic coefficients
defined as linear functions of the coefficients derivatives."""
[docs]
def __init__(
self,
reference_area,
reference_length,
coefficients,
center_of_pressure=(0, 0, 0),
name="Generic Linear Surface",
):
"""Create a generic linear aerodynamic surface, defined by its
aerodynamic coefficients derivatives. This surface is used to model any
aerodynamic surface that does not fit the predefined classes.
Important
---------
All the aerodynamic coefficients can be input as callable functions of
angle of attack, angle of sideslip, Mach number, Reynolds number,
pitch rate, yaw rate and roll rate. For CSV files, the header must
contain at least one of the following: "alpha", "beta", "mach",
"reynolds", "pitch_rate", "yaw_rate" and "roll_rate".
See Also
--------
:ref:`genericsurfaces`.
Parameters
----------
reference_area : int, float
Reference area of the aerodynamic surface. Has the unit of meters
squared. Commonly defined as the rocket's cross-sectional area.
reference_length : int, float
Reference length of the aerodynamic surface. Has the unit of meters.
Commonly defined as the rocket's diameter.
coefficients: dict, optional
List of coefficients. If a coefficient is omitted, it is set to 0.
The valid coefficients are:\n
cL_0: callable, str, optional
Coefficient of lift at zero angle of attack. Default is 0.\n
cL_alpha: callable, str, optional
Coefficient of lift derivative with respect to angle of attack.
Default is 0.\n
cL_beta: callable, str, optional
Coefficient of lift derivative with respect to sideslip angle.
Default is 0.\n
cL_p: callable, str, optional
Coefficient of lift derivative with respect to roll rate.
Default is 0.\n
cL_q: callable, str, optional
Coefficient of lift derivative with respect to pitch rate.
Default is 0.\n
cL_r: callable, str, optional
Coefficient of lift derivative with respect to yaw rate.
Default is 0.\n
cQ_0: callable, str, optional
Coefficient of side force at zero angle of attack.
Default is 0.\n
cQ_alpha: callable, str, optional
Coefficient of side force derivative with respect to angle of
attack. Default is 0.\n
cQ_beta: callable, str, optional
Coefficient of side force derivative with respect to sideslip
angle. Default is 0.\n
cQ_p: callable, str, optional
Coefficient of side force derivative with respect to roll rate.
Default is 0.\n
cQ_q: callable, str, optional
Coefficient of side force derivative with respect to pitch rate.
Default is 0.\n
cQ_r: callable, str, optional
Coefficient of side force derivative with respect to yaw rate.
Default is 0.\n
cD_0: callable, str, optional
Coefficient of drag at zero angle of attack. Default is 0.\n
cD_alpha: callable, str, optional
Coefficient of drag derivative with respect to angle of attack.
Default is 0.\n
cD_beta: callable, str, optional
Coefficient of drag derivative with respect to sideslip angle.
Default is 0.\n
cD_p: callable, str, optional
Coefficient of drag derivative with respect to roll rate.
Default is 0.\n
cD_q: callable, str, optional
Coefficient of drag derivative with respect to pitch rate.
Default is 0.\n
cD_r: callable, str, optional
Coefficient of drag derivative with respect to yaw rate.
Default is 0.\n
cm_0: callable, str, optional
Coefficient of pitch moment at zero angle of attack.
Default is 0.\n
cm_alpha: callable, str, optional
Coefficient of pitch moment derivative with respect to angle of
attack. Default is 0.\n
cm_beta: callable, str, optional
Coefficient of pitch moment derivative with respect to sideslip
angle. Default is 0.\n
cm_p: callable, str, optional
Coefficient of pitch moment derivative with respect to roll rate.
Default is 0.\n
cm_q: callable, str, optional
Coefficient of pitch moment derivative with respect to pitch rate.
Default is 0.\n
cm_r: callable, str, optional
Coefficient of pitch moment derivative with respect to yaw rate.
Default is 0.\n
cn_0: callable, str, optional
Coefficient of yaw moment at zero angle of attack.
Default is 0.\n
cn_alpha: callable, str, optional
Coefficient of yaw moment derivative with respect to angle of
attack. Default is 0.\n
cn_beta: callable, str, optional
Coefficient of yaw moment derivative with respect to sideslip angle.
Default is 0.\n
cn_p: callable, str, optional
Coefficient of yaw moment derivative with respect to roll rate.
Default is 0.\n
cn_q: callable, str, optional
Coefficient of yaw moment derivative with respect to pitch rate.
Default is 0.\n
cn_r: callable, str, optional
Coefficient of yaw moment derivative with respect to yaw rate.
Default is 0.\n
cl_0: callable, str, optional
Coefficient of roll moment at zero angle of attack.
Default is 0.\n
cl_alpha: callable, str, optional
Coefficient of roll moment derivative with respect to angle of
attack. Default is 0.\n
cl_beta: callable, str, optional
Coefficient of roll moment derivative with respect to sideslip
angle. Default is 0.\n
cl_p: callable, str, optional
Coefficient of roll moment derivative with respect to roll rate.
Default is 0.\n
cl_q: callable, str, optional
Coefficient of roll moment derivative with respect to pitch rate.
Default is 0.\n
cl_r: callable, str, optional
Coefficient of roll moment derivative with respect to yaw rate.
Default is 0.\n
center_of_pressure : tuple, optional
Application point of the aerodynamic forces and moments. The
center of pressure is defined in the local coordinate system of the
aerodynamic surface. The default value is (0, 0, 0).
name : str
Name of the aerodynamic surface. Default is 'GenericSurface'.
"""
super().__init__(
reference_area=reference_area,
reference_length=reference_length,
coefficients=coefficients,
center_of_pressure=center_of_pressure,
name=name,
)
self.compute_all_coefficients()
self.prints = _LinearGenericSurfacePrints(self)
self.plots = _LinearGenericSurfacePlots(self)
[docs]
def _get_default_coefficients(self):
"""Returns default coefficients
Returns
-------
default_coefficients: dict
Dictionary whose keys are the coefficients names and keys
are the default values.
"""
default_coefficients = {
"cL_0": 0,
"cL_alpha": 0,
"cL_beta": 0,
"cL_p": 0,
"cL_q": 0,
"cL_r": 0,
"cQ_0": 0,
"cQ_alpha": 0,
"cQ_beta": 0,
"cQ_p": 0,
"cQ_q": 0,
"cQ_r": 0,
"cD_0": 0,
"cD_alpha": 0,
"cD_beta": 0,
"cD_p": 0,
"cD_q": 0,
"cD_r": 0,
"cm_0": 0,
"cm_alpha": 0,
"cm_beta": 0,
"cm_p": 0,
"cm_q": 0,
"cm_r": 0,
"cn_0": 0,
"cn_alpha": 0,
"cn_beta": 0,
"cn_p": 0,
"cn_q": 0,
"cn_r": 0,
"cl_0": 0,
"cl_alpha": 0,
"cl_beta": 0,
"cl_p": 0,
"cl_q": 0,
"cl_r": 0,
}
return default_coefficients
[docs]
def compute_forcing_coefficient(self, c_0, c_alpha, c_beta):
"""Compute the forcing coefficient from the derivatives of the
aerodynamic coefficients."""
def total_coefficient(
alpha, beta, mach, reynolds, pitch_rate, yaw_rate, roll_rate
):
return (
c_0(alpha, beta, mach, reynolds, pitch_rate, yaw_rate, roll_rate)
+ c_alpha(alpha, beta, mach, reynolds, pitch_rate, yaw_rate, roll_rate)
* alpha
+ c_beta(alpha, beta, mach, reynolds, pitch_rate, yaw_rate, roll_rate)
* beta
)
return Function(
total_coefficient,
[
"alpha",
"beta",
"mach",
"reynolds",
"pitch_rate",
"yaw_rate",
"roll_rate",
],
["coefficient"],
)
[docs]
def compute_damping_coefficient(self, c_p, c_q, c_r):
"""Compute the damping coefficient from the derivatives of the
aerodynamic coefficients."""
def total_coefficient(
alpha, beta, mach, reynolds, pitch_rate, yaw_rate, roll_rate
):
return (
c_p(alpha, beta, mach, reynolds, pitch_rate, yaw_rate, roll_rate)
* roll_rate
+ c_q(alpha, beta, mach, reynolds, pitch_rate, yaw_rate, roll_rate)
* pitch_rate
+ c_r(alpha, beta, mach, reynolds, pitch_rate, yaw_rate, roll_rate)
* yaw_rate
)
return Function(
total_coefficient,
[
"alpha",
"beta",
"mach",
"reynolds",
"pitch_rate",
"yaw_rate",
"roll_rate",
],
["coefficient"],
)
[docs]
def compute_all_coefficients(self):
"""Compute all the aerodynamic coefficients from the derivatives."""
# pylint: disable=invalid-name
self.cLf = self.compute_forcing_coefficient(
self.cL_0, self.cL_alpha, self.cL_beta
)
self.cLd = self.compute_damping_coefficient(self.cL_p, self.cL_q, self.cL_r)
self.cQf = self.compute_forcing_coefficient(
self.cQ_0, self.cQ_alpha, self.cQ_beta
)
self.cQd = self.compute_damping_coefficient(self.cQ_p, self.cQ_q, self.cQ_r)
self.cDf = self.compute_forcing_coefficient(
self.cD_0, self.cD_alpha, self.cD_beta
)
self.cDd = self.compute_damping_coefficient(self.cD_p, self.cD_q, self.cD_r)
self.cmf = self.compute_forcing_coefficient(
self.cm_0, self.cm_alpha, self.cm_beta
)
self.cmd = self.compute_damping_coefficient(self.cm_p, self.cm_q, self.cm_r)
self.cnf = self.compute_forcing_coefficient(
self.cn_0, self.cn_alpha, self.cn_beta
)
self.cnd = self.compute_damping_coefficient(self.cn_p, self.cn_q, self.cn_r)
self.clf = self.compute_forcing_coefficient(
self.cl_0, self.cl_alpha, self.cl_beta
)
self.cld = self.compute_damping_coefficient(self.cl_p, self.cl_q, self.cl_r)
[docs]
def _compute_from_coefficients(
self,
rho,
stream_speed,
alpha,
beta,
mach,
reynolds,
pitch_rate,
yaw_rate,
roll_rate,
):
"""Compute the aerodynamic forces and moments from the aerodynamic
coefficients.
Parameters
----------
rho : float
Air density.
stream_speed : float
Magnitude of the airflow speed.
alpha : float
Angle of attack in radians.
beta : float
Sideslip angle in radians.
mach : float
Mach number.
reynolds : float
Reynolds number.
pitch_rate : float
Pitch rate in radians per second.
yaw_rate : float
Yaw rate in radians per second.
roll_rate : float
Roll rate in radians per second.
Returns
-------
tuple of float
The aerodynamic forces (lift, side_force, drag) and moments
(pitch, yaw, roll) in the body frame.
"""
# Precompute common values
dyn_pressure_area = 0.5 * rho * stream_speed**2 * self.reference_area
dyn_pressure_area_damping = (
0.5 * rho * stream_speed * self.reference_area * self.reference_length / 2
)
dyn_pressure_area_length = dyn_pressure_area * self.reference_length
dyn_pressure_area_length_damping = (
0.5
* rho
* stream_speed
* self.reference_area
* self.reference_length**2
/ 2
)
# Compute aerodynamic forces
lift = dyn_pressure_area * self.cLf(
alpha, beta, mach, reynolds, pitch_rate, yaw_rate, roll_rate
) + dyn_pressure_area_damping * self.cLd(
alpha, beta, mach, reynolds, pitch_rate, yaw_rate, roll_rate
)
side = dyn_pressure_area * self.cQf(
alpha, beta, mach, reynolds, pitch_rate, yaw_rate, roll_rate
) + dyn_pressure_area_damping * self.cQd(
alpha, beta, mach, reynolds, pitch_rate, yaw_rate, roll_rate
)
drag = dyn_pressure_area * self.cDf(
alpha, beta, mach, reynolds, pitch_rate, yaw_rate, roll_rate
) + dyn_pressure_area_damping * self.cDd(
alpha, beta, mach, reynolds, pitch_rate, yaw_rate, roll_rate
)
# Compute aerodynamic moments
pitch = dyn_pressure_area_length * self.cmf(
alpha, beta, mach, reynolds, pitch_rate, yaw_rate, roll_rate
) + dyn_pressure_area_length_damping * self.cmd(
alpha, beta, mach, reynolds, pitch_rate, yaw_rate, roll_rate
)
yaw = dyn_pressure_area_length * self.cnf(
alpha, beta, mach, reynolds, pitch_rate, yaw_rate, roll_rate
) + dyn_pressure_area_length_damping * self.cnd(
alpha, beta, mach, reynolds, pitch_rate, yaw_rate, roll_rate
)
roll = dyn_pressure_area_length * self.clf(
alpha, beta, mach, reynolds, pitch_rate, yaw_rate, roll_rate
) + dyn_pressure_area_length_damping * self.cld(
alpha, beta, mach, reynolds, pitch_rate, yaw_rate, roll_rate
)
return lift, side, drag, pitch, yaw, roll
