Parachute Class

class rocketpy.Parachute.Parachute(name, cd_s, trigger, sampling_rate, lag, noise=(0, 0, 0))

Keeps parachute information.

name

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.

Type:

string

cd_s

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.

Type:

float

trigger

Function which defines if the parachute ejection system is to be triggered. It must take as input the freestream pressure in pascal, the height in meters (above ground level), and the state vector of the simulation, which is defined by [x, y, z, vx, vy, vz, e0, e1, e2, e3, wx, wy, wz]. It will be called according to the sampling rate given next. It should return True if the parachute ejection system is to be triggered and False otherwise.

Type:

function

sampling_rate

Sampling rate, in hertz, for the trigger function.

Type:

float

lag

Time, in seconds, between the parachute ejection system is triggered and the parachute is fully opened.

Type:

float

noiseBias

Mean value of the noise added to the pressure signal, which is passed to the trigger function. Unit is in pascal.

Type:

float

noiseDeviation

Standard deviation of the noise added to the pressure signal, which is passed to the trigger function. Unit is in pascal.

Type:

float

noiseCorr

Tuple with the correlation between noise and time.

Type:

tuple, list

noiseSignal

List of (t, noise signal) corresponding to signal passed to trigger function. Completed after running a simulation.

Type:

list

noisyPressureSignal

List of (t, noisy pressure signal) that is passed to the trigger function. Completed after running a simulation.

Type:

list

cleanPressureSignal

List of (t, clean pressure signal) corresponding to signal passed to trigger function. Completed after running a simulation.

Type:

list

noiseSignalFunction

Function of noiseSignal.

Type:

Function

noisyPressureSignalFunction

Function of noisyPressureSignal.

Type:

Function

cleanPressureSignalFunction

Function of cleanPressureSignal.

Type:

Function

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 (function, float, string) – Function which defines if the parachute ejection system is to be triggered. It must take as input the freestream pressure in pascal, the height in meters (above ground level), and the state vector of the simulation, which is defined by [x, y, z, vx, vy, vz, e0, e1, e2, e3, wx, wy, wz]. It will be called according to the sampling rate given next. It should return True if the parachute ejection system is to be triggered and False otherwise.

• 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) – 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