Thanks everyone!
Paul,
The second book is much better than the first. I have given away 13,500+ copies of Mr. Planemaker's Flying Machine, but readers will not buy the sequel. They expect it to be available for free, then they will download it. I wrote the second for readers' entertainment, not because I had a burning desire to write a series of books. If they don't want to buy it, that's fine. If they prefer to spend their money on other books, that's fine too. Sometimes, we have to accept that readers are not prepared to buy the books we write, even though they would probably read them if they were free. It's the way it is.