The chart_rule_generator creates PDFs containing a nautical mile scale and a lookup table (aligned with the scale) for the time taken to fly a given distance for a set of speeds.

The rule is designed for use on aviation charts and, suitably cropped and laminated, can be used to quickly measure distances and the time to cover said distance in flight; without having to resort to mental arithmetic or a whizz wheel.

By default the rule is for a 1:500,000 scale chart and goes from 0 to 50 nautical miles. The speeds on the look up table go from 60 to 120 kts in 10 kt increments.

Please note that while the PDF produced is as accurate as possible, there may be some scaling factor applied to the printed output by your printer driver, the printer itself or the choice of paper used for printing (currently the generator always produces A4 output). Make sure you compare the rule's scale with a known accurate scale before using it.

Dependencies

The chart_rule_generator requires:

• Python 2.4
• The ReportLab toolkit, an open-source Python toolkit for generating PDF files. Available as a package for most Linux distributions. The source code, as well as prebuilt Windows DLLs, can be found on their website: http://www.reportlab.org/downloads.html

Usage

The generator is driven by a configuration file. This file specifies the layout of the chart (e.g. number of nautical miles on rule, speeds on lookup) and how it looks (e.g. font used, font size, colours/shading on rule).

To generate a default configuration file, use the "--create" option ...

This file can then be passed in to the generator using the "--input" options to create a chart; in this case "mychart.pdf" ...

The "mychart.pdf" file can now be opened using your PDF reader of choice and printed out.

The configuration file contains comments on each entry and can easily be configured to suit your needs. Just remember to leave the "[chart]" section heading untouched, otherwise the generator will not be able to find your settings.

Known Issues

• The generator is currently limited to producing charts on A4 (8.3" x 11.7") paper. If printing on to other paper sizes, be careful that the output isn't rescaled.
• No support for double-sided charts. It is possible to produce double-sided charts; but this must be done via manual duplex printing or by sticking two equally sized charts back-to-back.

Installation

The chart_rule_generator uses the standard Python distribution utilities. So it should just be a case of uncompressing the archive and running:

Obviously the user running this must have sufficient permissions to create a file in the install directory.

Examples

Default chart: 50nm, 60-120kts	More colourful chart: 30nm, 70-100kts
A 1:250,000 chart: 25nm, 110-160kts