Parachute Class#

class rocketpy.Parachute[source]#

Keeps parachute information.

Variables:

Parachute.name (string) – Parachute name, such as drogue and main. Has no impact in simulation, as it is only used to display data in a more organized matter.
Parachute.cd_s (float) – Drag coefficient times reference area for parachute. It is used to compute the drag force exerted on the parachute by the equation F = ((1/2)*rho*V^2)*cd_s, that is, the drag force is the dynamic pressure computed on the parachute times its cd_s coefficient. Has units of area and must be given in squared meters.
Parachute.trigger (callable, float, str) –
This parameter defines the trigger condition for the parachute ejection system. It can be one of the following:
- A callable function that takes three arguments:
1. Freestream pressure in pascals.
2. Height in meters above ground level.
3. The state vector of the simulation, which is defined as:
  
  [x, y, z, vx, vy, vz, e0, e1, e2, e3, wx, wy, wz].
The function should return True if the parachute ejection system should be triggered and False otherwise.
- A float value, representing an absolute height in meters. In this
case, the parachute will be ejected when the rocket reaches this height above ground level.
- The string “apogee” which triggers the parachute at apogee, i.e.,
when the rocket reaches its highest point and starts descending.

Note: The function will be called according to the sampling rate specified.
Parachute.triggerfunc (function) –
This parameter defines the trigger function created from the trigger parameter. It is used to evaluate the trigger condition for the parachute ejection system. It is a callable function that takes three arguments:
1. Freestream pressure in pascals.
2. Height in meters above ground level.
3. The state vector of the simulation, which is defined as:
  
  [x, y, z, vx, vy, vz, e0, e1, e2, e3, wx, wy, wz].
The function should return True if the parachute ejection system should be triggered and False otherwise.

Note: The function will be called according to the sampling rate specified.
Parachute.sampling_rate (float) – Sampling rate, in hertz, for the trigger function.
Parachute.lag (float) – Time, in seconds, between the parachute ejection system is triggered and the parachute is fully opened.
Parachute.noise_bias (float) – Mean value of the noise added to the pressure signal, which is passed to the trigger function. Unit is in pascal.
Parachute.noise_deviation (float) – Standard deviation of the noise added to the pressure signal, which is passed to the trigger function. Unit is in pascal.
Parachute.noise_corr (tuple, list) – Tuple with the correlation between noise and time.
Parachute.noise_signal (list of tuple) – List of (t, noise signal) corresponding to signal passed to trigger function. Completed after running a simulation.
Parachute.noisy_pressure_signal (list of tuple) – List of (t, noisy pressure signal) that is passed to the trigger function. Completed after running a simulation.
Parachute.clean_pressure_signal (list of tuple) – List of (t, clean pressure signal) corresponding to signal passed to trigger function. Completed after running a simulation.
Parachute.noise_signal_function (Function) – Function of noiseSignal.
Parachute.noisy_pressure_signal_function (Function) – Function of noisy_pressure_signal.
Parachute.clean_pressure_signal_function (Function) – Function of clean_pressure_signal.

__init__(name, cd_s, trigger, sampling_rate, lag=0, noise=(0, 0, 0))[source]#

Initializes Parachute class.

Parameters:

name (string) – Parachute name, such as drogue and main. Has no impact in simulation, as it is only used to display data in a more organized matter.
cd_s (float) – Drag coefficient times reference area of the parachute.
trigger (callable, float, str) –
This parameter defines the trigger condition for the parachute ejection system. It can be one of the following:
- A callable function that takes three arguments:
  1. Freestream pressure in pascals.
  2. Height in meters above ground level.
  3. The state vector of the simulation, which is defined as:
    [x, y, z, vx, vy, vz, e0, e1, e2, e3, wx, wy, wz].
The function should return True if the parachute ejection system should be triggered and False otherwise.
- A float value, representing an absolute height in meters. In this
case, the parachute will be ejected when the rocket reaches this height above ground level.
- The string “apogee” which triggers the parachute at apogee, i.e.,
when the rocket reaches its highest point and starts descending.

Note: The function will be called according to the sampling rate specified next.
sampling_rate (float) – Sampling rate in which the parachute trigger will be checked at. It is used to simulate the refresh rate of onboard sensors such as barometers. Default value is 100. Value must be given in hertz.
lag (float, optional) – Time between the parachute ejection system is triggered and the parachute is fully opened. During this time, the simulation will consider the rocket as flying without a parachute. Default value is 0. Must be given in seconds.
noise (tuple, list, optional) – List in the format (mean, standard deviation, time-correlation). The values are used to add noise to the pressure signal which is passed to the trigger function. Default value is (0, 0, 0). Units are in pascal.

Return type:

None

__str__()[source]#

Returns a string representation of the Parachute class.

Returns:: String representation of Parachute class. It is human readable.
Return type:: string

__repr__()[source]#: Representation method for the class, useful when debugging.

info()[source]#: Prints information about the Parachute class.

all_info()[source]#: Prints all information about the Parachute class.