RocketPy

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Is your feature request related to a problem? Please describe.

RocketPy supports parachute trigger functions, which can be quite nice to test ejection activation algorithms. However, when running simple simulations with parachutes, having to code a trigger function can be an unnecessary overhead.

Describe the solution you'd like

I would like the trigger argument of the Flight.addParachute method to support, besides a callable, two other types of input:

• a string 'apogee', in which case, the parachute would be ejected at apogee (intuitive I believe)
• a numeric value, such as 1400, in which case the parachute would be ejected at an altitude (above sea level, ASL) corresponding to the numeric value in meters.

Here is a code snippet showcasing both:

Main = Calisto.addParachute(
    "Main",
    CdS=10.0,
    trigger=800,
    samplingRate=105,
    lag=1.5,
    noise=(0, 8.3, 0.5),
)

Drogue = Calisto.addParachute(
    "Drogue",
    CdS=1.0,
    trigger='apogee',
    samplingRate=105,
    lag=1.5,
    noise=(0, 8.3, 0.5),
)

Implementation details

Internally, the Rocket.addParachute method may convert both types of new inputs into trigger functions (callables) which will continue to work with the Flight Class without the need of modifying it.

Additional context

Such a feature would facilitate the creation of parachutes, making RocketPy easier to use. This is particularly important for inexperienced users. Furthermore, the advanced feature of using a trigger function would keep working exactly as it does today.

It is also important to note that this idea originated when using RocketPy in MATLAB. Currently, a function needs to be defined in Python inside MATLAB to create the triggers, which is awfully bad for user experience, since it can only be done with lambdas. Therefore, such a feature would also greatly enhance the experience for MATLAB users.