Add opening shock force estimation to Parachute class - #1050
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ArthurJWH merged 2 commits intoAug 5, 2026
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Adds an opening_shock_coefficient parameter and a calculate_opening_shock_force method to estimate the peak transient force during parachute inflation, following the simplified model in Knacke's Parachute Recovery Systems Design Manual (1992, Section 5.5). Closes RocketPy-Team#161
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@Matanski please rebase your work on top of the develop branch, your PR should be targeting develop (not master) |
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Since this is a simplified equation for the opening shock force that would not directly impact the flight simulation, I believe that it would be better to add it as an utilities function (e.g. |
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ArthurJWH
merged commit Aug 5, 2026
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Summary
Addresses #161 — estimates the peak transient "opening shock" force
experienced by recovery hardware during parachute inflation.
Changes
opening_shock_coefficientparameter toParachute.__init__(default 1.5, per Knacke's typical range of 1.2–2.0).
Parachute.calculate_opening_shock_force(air_density, velocity),implementing F₀ = Cx · Cd·S · q from Knacke's "Parachute Recovery
Systems Design Manual" (1992, Section 5.5).
to_dict/from_dictwith backward-compatible defaulting for old serialized data.
scaling, and serialization round-trip.
Test plan
pytest tests/unit/rocket/test_parachute.py— 19 passedpytest tests/unit— 1546 passed, 12 skipped