AFAIK, the canted tail rotor on the UH-60 was largely driven by the UTTAS requirement to transport two airframes by a USAF C-141. At the time, this was thought to be the primary means of deployment to Europe and Asia. The Boeing YUH-61 competitor met the requirement by folding the tailboom at approximately the 2/3 point, allowing two helicopters to fit (length and height). Sikorsky choose an angled fold at the aft end of the tailboom, and shortened the length of the nose in order to fit. The shortened nose of the UH-60 created an aircraft with a predominant aft cg and reduced cg range. The canted tail rotor was incorporated to overcome these shortcomings. Fly by wire at the time was discounted because of its considerable technical risk (on the stabilator it posed problems for years), so a mechanical mixing unit helped deal with the cross-coupling created by the canted tail rotor. Both aircraft incorporated stabilators to further improve handling qualities, with the UH-60’s also assisting with the aft cg issues of extreme nose high attitudes during hover and low-speed. During early testing, lost tail rotor thrust also necessitated removal of a large chunk of the UH-60's cambered vertical fin.