I've had my idea of an illustrated book called "An Illustrated Guide to Starships" rekindled. That is a book that looked at potential real starship designs, illustrated them and discussed the possible viability of them in the future. I've wanted to illustrate such a book heavily but don't know how to hook up with a professional illustrator. I've wondered if any of the images dropped on Google Images might be allowed for free use? If you google "Interstellar Ramjet" for example you get a whole host of images
Most of the images that turn up are copyrighted to whoever originally made them. There are "free" image repositories but the stuff in them is either not very good or has an obvious watermark on it. You'd be much better off contracting a professional illustrator to make your images for you. I'll tell you up front, good illustrators, especially good technical illustrators, are not cheap.
Google Images isn't a source; it's just a method of finding things. So asking if pictures on Google Images are fair game is like asking if books in a library are fair game ... it depends on the book. Some will be public domain, most will not. However, Google does have a useful tool for locating images that are specifically labeled as being OK to reuse. Enter a search term, then on the results page, click "Search tools," then "Usage rights."
You can also look on Flickr to search just Creative Commons licenses. Also, many people on deviantArt describe what they will allow done with their images.
