Rocket Parachute Size Calculator
|
|
| Menu location |
|---|
| Rocket → Calculators → Parachute Size Calculator |
| Workbenches |
| Rocket Workbench |
| Default shortcut |
| None |
| Introduced in version |
| 0.19 |
| See also |
| None |
Description[edit | edit source]
This calculator determines the parachute size required to achieve the desired descent rate based on the parachute parameters.
The desired descent rate depends on your needs. As a rule of thumb, the main parachute should slow the rocket to approximately while the drone should allow the parachute to descend much faster - . The editor has presets for these, with the value for the drogue being in the middle of the range. You can set a custom descent rate to suit your needs.
A key value for determining the descent rate is the coefficient of drag (). The exact value of this will depend on a variety of factors including the shape of the parachute. Presets are provided for parachutes cut from a flat piece of material (round, square, hexagonal) such as those provided by many kits, and for a true dome shape. Your parachute manufacturer may provide a better value for this coefficient.
Usage[edit | edit source]
- There are several ways to invoke the command:
- Press the
Parachute Size Calculator button.
- Select the Rocket → Calculators →
Parachute Size Calculator option from the menu.
- Press the
- Enter the weight of your rocket and parameters for your parachute.
Calculation[edit | edit source]
Parachute size is determined by the mass of the rocket, desired descent rate, and drag characteristics of the parachute. The calculation is a two step process. First the area of the parachute is calculated:
where
- the mass of the rocket
- desired terminal velocity
- drag coefficient of the parachute
- air density, average at sea level in at
- acceleration due to gravity in
The diameter is then calculated from the surface area based on the shape.
For hexagonal parachutes:
For square parachutes, the diameter is the length of each side
For all other parachutes, the shape is assumed to be circular
Units[edit | edit source]
Calculations are done using metric units, but will display in your preferred units. Values can also be entered using any supported units by including the units with the value (eg 5 oz, or 23.2 g)
References[edit | edit source]
- http://www.rocketmime.com/rockets/descent.html
- https://descentratecalculator.onlinetesting.net/
- https://www.math.net/area-of-a-hexagon
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