Checking the scaling of a PDF plan

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Summary

To check the scaling of a PDF plan, use your PDF reader software, and the 'measure' tool.
 

Details

Knowing a plan is scaled correctly (scaled to full size) is important if you want to print it to paper and build on it. You need to know that the dimensioned wood sizes and parts, wheels, etc will be printed at correct full size.

Your PDF reader software will help you check this.

Here is a real world example. Let's say we are interested in the Ken Willard Breathless (oz5842) plan. We are using a Windows 10 PC, and we have installed Acrobat Reader as our PDF reader. (For more on PDF software see Software to read PDF files).

Here's how to check the scaling of the plan:

  • Download the PDF plan file Breathless_38in_oz5842.pdf from https://outerzone.co.uk/plan_details.asp?ID=5842

  • Open the plan in Acrobat Reader.

  • Use the top menu Tools>Measure to display the Measure toolbar (image #1).

  • Zoom in on the scale reference bar at the bottom right of the plan. Use the measure tool to check that dimension of 6 inches (image #2).

In this example, the scaling is correct.
 

Notes

Some plans of course do not have a scale reference bar. In that case you'll need to look out for another dimensioned item to measure, such as the mainwheel size - which is 2 inch on the Breathless (image #3) - or failing that the stock sizes of wood specified (eg the trailing edge of the wing on the Breathless is 3/4 in).

You can of course always just measure the wingspan itself, assuming you know the correct value. On the Breathless plan the wing-half shown measures 19.09 in, giving a total wingspan of 38.18 in.
 

1. Selecting Tools/Measure
1. Selecting Tools/Measure
2. Using the measure tool
2. Using the measure tool
3. Checking dimensions of the main wheel
3. Checking dimensions of the main wheel

KB106
Checking the scaling of a PDF plan
SteveWMD
22/07/2019 (revised: 17/09/2024)