Dave,
Thanks for the link to that XV-15 book download. I'm glad to see that NASA put that into the public domain. Especially since the work was funded with tax dollars.
I know you're Canadian, but it's great to see that some of my hard-earned US tax dollars are coming back as something useful and accessible to the general public. If you had to buy that book, it would probably cost $50 or $60.
And with the currently devalued US dollar, that would still be $50 or $60 (Cdn)!