Yes, you can read it for free online (PDF), but it gets kinda annoying after a while, and I would recommend just buying the book.

When I first learned to fly, I decided to get my glider pilot license before I got my airplane single engine land. The book I read was "Glider Flying Handbook." It was a very good and informative book. I have personally never read the Airplane Flying Handbook from front to back, but I do own a copy and I have several pages bookmarked. It is a good resource. I usually use the Jeppesen book for private students, and it works well. But the Airplane Flying Handbook should be a good resource.