3 links
Boeing Sikorsky RAH-66 Stealth Comanche Helicopter
abovetopsecret.com
Information on the RAH-66 Stealth Comanche helicopter and the stealth technology used in it.
Helicopter Aviation
copters.com
This site deals with the aerodynamics of helicopters, instruction on how to fly helicopters, mechanical components, and helicopter maneuvers.
How Helicopters Work
howstuffworks.com
Photos and many brief videos in this narrative help to describe helicopter controls, capabilities and complexity.