Donation Sponsor

$5 $10 $25 $100 $200 Other

If you are not sure or not able to commit to a regular donation, but still want to help the project, you can do a one-time donation, of any amount.

Choose freely the amount you wish to donate one time only.

We call sponsoring the act of donating money recurrently to the FreeCAD project. You can do that as an individual or as a company or institution, through different channels or platforms, depending on your preferences.

Sponsoring FreeCAD allows its developers to count on a steady flow of income, so it allows the FPA to plan things ahead, and the FreeCAD developers to invest themselves more seriously into FreeCAD.

To encourage persons and companies to sponsor the FreeCAD project, we have created different sponsoring tiers. When donating regularly to the project, unless you prefer to stay anonymous, your name, company name and/or logo will be featured on this website, depending on the tier you fit into:

♥ Normal sponsor : from 1 USD / 1 EUR per month. You will not have your name displayed here, but you will have helped the project a lot anyway. Together, normal sponsors maintain the project on its feet as much as the bigger sponsors.
🥉 Bronze sponsor : from 25 USD / 25 EUR per month. Your name or company name is displayed on this page.
🥈 Silver sponsor : from 100 USD / 100 EUR per month. Your name or company name is displayed on this page, with a link to your website, and a one-line description text.
🥇 Gold sponsor : from 200 USD / 200 EUR per month. Your name or company name and logo displayed on this page, with a link to your website and a custom description text. Companies that have helped FreeCAD early on also appear under Gold sponsors.

Instead of donating each month, you might find it more comfortable to make a one-time donation that, when divided by twelve, would give you right to enter a sponsoring tier. Don't hesitate to do so!

Choose freely the amount you wish to donate each month.

Please inform your forum name or twitter handle as a notein your transfer, or reach to us, so we can give you proper credits!

GuiCommand: Name: Rocket Vent Hole Size Calculator Icon: Rocket_Calculator.svg MenuLocation: Rocket , Calculators , Vent Hole Size Calculator Workbenches: Rocket_Workbench Version: 0.19

Rocket Vent Hole Size Calculator

Description

This calculator determines the minimum size of vent holes for barometric altimeters based on the volume of the space and the number of vent holes.

Calculation comes from the rule of thumb of 1/4\" vent hole for every 100 cubic inches of volume. A single vent hole of the appropriate size is susceptible to noise caused by breezes and wind gusts. These effects are minimized by using multiple vent holes distributed around the volume, with 3 holes being considered a practical minimum. The combined area of all vent holes will be equivalent to that of a single larger hole.

Usage

There are several ways to invoke the command:
- Press the Vent Hole Size Calculator button.
- Select the Rocket → Calculators → Vent Hole Size Calculator option from the menu.
Enter the parameters of your electronics bay.

Calculation

Vent hole size is calculated using the following formula:

$$D_{vent} = 0.004396 D \sqrt{\cfrac{L}{N}}$$

where

$$D_{vent} =$$ vent hole size

$$D =$$ body tube diameter

$$L =$$ body tube length

$$N =$$ number of vent holes

Units

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

http://vernk.com/AltimeterPortSizing.htm

⏵ documentation index > Addons > External Workbenches > Rocket Vent Hole Size Calculator

This page is retrieved from https://github.com/FreeCAD/FreeCAD-documentation/blob/main/wiki/Rocket_Vent_Hole_Size_Calculator.md