Bell Model 533 in flight (1963) 

I personally feel like not a-lot of people have heard about this helicopter, very underrated.

Notice the 7 degree forward tilt of the main rotor mast?, They installed the forward gear box from a Chinook, and later installed a 3 bladed rotor on later tests, The Kaman blades and M model hub here was a test item - Neat stuff here

I would love to see footage of the rigid rotor they experimented with.

Intress

There is a another vid of this helo flying MOE going crazy fast

This is the fastest helicopter ever.. Not the X-3...