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https://github.com/rreusser/naca-four-digit-airfoil
The equations for a NACA four-digit series airfoil
https://github.com/rreusser/naca-four-digit-airfoil
Last synced: 3 months ago
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The equations for a NACA four-digit series airfoil
- Host: GitHub
- URL: https://github.com/rreusser/naca-four-digit-airfoil
- Owner: rreusser
- Created: 2016-01-11T02:40:25.000Z (about 9 years ago)
- Default Branch: master
- Last Pushed: 2018-09-04T17:00:13.000Z (over 6 years ago)
- Last Synced: 2024-10-26T12:18:31.381Z (3 months ago)
- Language: JavaScript
- Size: 26.4 KB
- Stars: 10
- Watchers: 4
- Forks: 1
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
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README
# naca-four-digit-airfoil
[](https://travis-ci.org/rreusser/naca-four-digit-airfoil) [](http://standardjs.com/) [](https://badge.fury.io/js/naca-four-digit-airfoil)
> The equations for a NACA four-digit series airfoil
## Introduction
NACA airfoils map a four digit code to an airfoil shape. For example, a '2412' airfoil is parsed to mean:
- The leading '2' indicates maximum camber is 2% of chord length
- The '4' indicates maximum camber is at 40% of the chord length
- The '12' indicates maximum thickness is 12% of the chord length
[](http://rreusser.github.io/naca-four-digit-airfoil/?naca=2412)
Live examples (change the query string to create your own):
- [NACA 2412](http://rreusser.github.io/naca-four-digit-airfoil/?naca=2412)
- [NACA 0012](http://rreusser.github.io/naca-four-digit-airfoil/?naca=0012)
- [NACA 3418](http://rreusser.github.io/naca-four-digit-airfoil/?naca=3418)
## Example
The code below calculates the x- and y-coordinates of the upper and lower surfaces, respectively, at 50% of the chord length.
```javascript
var naca = require('naca-four-digit-airfoil')
naca('2412').evaluate(0.5)
// => [ 0.5005881887154037, 0.07238142883077964, 0.4994118112845963, -0.03349253994189075 ]
```
## Installation
```bash
$ npm install naca-four-digit-airfoil
```
## API
### Based on NACA Code
#### `require('naca-four-digit-airfoil')(nacaAirfoilCode[, chordLength = 1])`
Parses the airfoil code and returns an object with functions that evaluate the shape of the airfoil for a unit chord length. Arguments are:
- **`nacaAirfoilCode`**: A four-digit string containing the NACA airfoil code. The first digit is the amount of camber in units of 1% of the chord length. The second digit is the location of maximum camber measured from the leading edge in units of 10% of the chord length. The final two digits are the thickness of the airfoil in units of 1% of the chord length.
- **`chordLength`** (optional, default = 1): The chord length of the airfoil.
The object returned contains the following functions:
- **`thickness: function(x)`**: The half-thickness of the airfoil above or below the camber line at position x.
- **`camberLine: function(x)`**: The height of the camber line above the centerline at position `x`.
- **`camberLineSlope: function(x)`**: The slope of the camber line at position `x`.
- **`leadingEdgeRadius: function()`**: The radius of curvature of the leading edge.
- **`evaluate: function(x)`**: The coordinates of the surface at position `x`. Returned in a four-element array containing coordinates `[xUpper, yUpper, xLower, yLower]`. The coordinates are calculated perpendicular to the line of camber. So that the x-coordinate of the surface at chord position `x` is slightly perturbed.
- **`xUpper: function(x)`**: The x-coordinate of the upper surface of the airfoil.
- **`yUpper: function(x)`**: The y-coordinate of the upper surface of the airfoil.
- **`xLower: function(x)`**: The x-coordinate of the lower surface of the airfoil.
- **`yLower: function(x)`**: The y-coordinate of the lower surface of the airfoil.
### As Plain Functions
The functions are also available as unadorned functions accessible on the plain module. Using the variables defined above, they are:
- **`parse`**: `function(code)`: Parse the four-character `String` airfoil code, returning `m` (the amount of camber as a fraction of chord length), `p` (the location of maximum camber as a fraction of chord length), and `t` (thickness as a fraction of chord length).
- **`thickness`**: `function(x, c, t)`
- **`camberLine`**: `function(x, c, m, p)`
- **`camberLineSlope`**: `function(x, c, m, p)`
- **`leadingEdgeRadius`**: `function(t, c)`
- **`xLower`**: `function(x, c, m, p, t)`
- **`xUpper`**: `function(x, c, m, p, t)`
- **`yLower`**: `function(x, c, m, p, t)`
- **`yUpper`**: `function(x, c, m, p, t)`
- **`evaluate`**: `function(x, c, m, p, t)`
## License
© 2016 Ricky Reusser. MIT License.