Photos of Lockheed XH-51ASource:http://nhungdoicanh.blogspot.com/2012/03/lockheed-xh-51.html
As the Lockheed main thread is closed I must post it here.
Lockheed research paper for Advanced Anti-Torque Concepts Study for Model 286 helicopter(one of my favorite light helicopters).
Lots of drawings, cutaways a feast for eyes, enjoy it!!!