Issue #74: team-01 - Opening Shock Forces

[aasitvora99]

Pull request type

Please check the type of change your PR introduces:

• Code base additions (bugfix, features)
• Code maintenance (refactoring, formatting, renaming, tests)
• ReadMe, Docs and GitHub maintenance
• Other (please describe):

Pull request checklist

Please check if your PR fulfills the following requirements, depending on the type of PR:

• ReadMe, Docs and GitHub maintenance:

  • Spelling has been verified
  • Code docs are working correctly

• Code base maintenance (refactoring, formatting, renaming):

  • Docs have been reviewed and added / updated if needed
  • Lint (black rocketpy) has passed locally and any fixes were made
  • All tests (pytest --runslow) have passed locally

• Code base additions (for bug fixes / features):

  • Tests for the changes have been added
  • Docs have been reviewed and added / updated if needed
  • Lint (black rocketpy) has passed locally and any fixes were made
  • All tests (pytest --runslow) have passed locally

What is the current behavior?

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What is the new behavior?

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Does this introduce a breaking change?

• Yes
• No

Other information

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[FranzYuri]

Hi @aasitvora99! Thank you so much for this work! Great to see that you grasped the idea of using the parachute events to get the precise velocity (an idea to make the code even more precise is to find also the air density this way).
One think I am curious though is about the formula you used at line 1607 in Flight.py. Did you used Knacke's formula and assumed the opening force coefficient and force reduction factor to be both 1, or is the formula you used something else?

[aasitvora99]

Yes. the Equation used in line 1607 was a subset of Knacke's formula, which is a simple drag equation (1/2 Cd rho av^2). I wanted to include Knacke's formula too but I wanted to test adding the feature to Flight.py first. Learning how to use different classes in rocketpy was the first priority.
Plus my original idea was to include shock factors on some of the commonly used parachute shapes found on the market (cross, parafoil, torroidal, annular etc).
The calculations you get when you run parachuteSnatchForce function are far from practical at the moment as it doesn't take account on several other factors, but I'll try refactoring my code to include these params.

[FranzYuri]

I see. Well, good and simple implementation, well done!