LGNYC,
Yes, all three books are excellent, the second gives some more general theoretical info and the third goes into design and historical information including some interesting type specific and experimental stuff.
Shame you didn't ask before. I ordered a set of all three books a few years ago (via Rotor and Wing, I think). After some weeks had gone by they hadn't arrived so I got in touch with the magazine and they sent a second set. The "lost" originals turned up on the same day as the replacements!
I gave the "free" set away a while back to someone who possibly hasn't even looked at them since ...... sorry
Cierva's full-sized aircraft rolled over because unlike his models, which used flexible materials of cane and feathers, he deliberately but mistakenly made a rigid rotor system (blade bracing wires from a kingpost).
He had not given the pilot a sufficiently powerful method of overcoming the effects of inflow roll and flapback, that's why it rolled into a ball. He subsequently used flapping blade hinges which allowed flapping to equality and this relieved feedback forces to the airframe, so the aircraft became more stable and controllable.
Ray Prouty also dispels the theory (sometimes expounded not far from here) that a helicopter is controlled by precessing its "gyroscopic" rotor system. That might get a bite LOL
