English: A 3-view line drawing of the Sikorsky R-4.
Date
Source
AN 01-230HA-2, Page vi. Scanned and provided via email by Patrick Hibbard of the eBay account Warbirds and Trains. Full manual available for purchase via eBay.
Author
U.S. Military via Patrick Hibbard
Licensing
This image is in the public domain because it is a mere mechanical scan or photocopy of a public domain original, or – from the available evidence – is so similar to such a scan or photocopy that no copyright protection can be expected to arise. The original itself is in the public domain for the following reason:
This tag is designed for use where there may be a need to assert that any enhancements (eg brightness, contrast, colour-matching, sharpening) are in themselves insufficiently creative to generate a new copyright. It can be used where it is unknown whether any enhancements have been made, as well as when the enhancements are clear but insufficient. For known raw unenhanced scans you can use an appropriate {{PD-old}} tag instead. For usage, see Commons:When to use the PD-scan tag.
Note: This tag applies to scans and photocopies only. For photographs of public domain originals taken from afar, {{PD-Art}} may be applicable. See Commons:When to use the PD-Art tag.
Captions
Add a one-line explanation of what this file represents
Uploaded a work by U.S. Military via Patrick Hibbard from AN 01-230HA-2, Page vi. Scanned and provided via email by Patrick Hibbard of the eBay account [http://www.ebay.com/str/warbirdsandtrains Warbirds and Trains]. Full manual available for purchase via [http://www.ebay.com/itm/253825259817 eBay]. with UploadWizard