RAH-66 Comanche Tethered Hover

Tethered hover is a standard test technique used to establish the variation of hover power with gross weight, and was an important aspect of the recent successful completion of Milestone II exit criteria for the RAH-66 Comanche program. Using theory, numerical analysis, piloted simulation, and flight test data, this paper considers a variety of flight mechanics issues related to the conducting of the tethered hover testing on Comanche. The paper begins with a brief review of the requirements and procedures for conducting tethered hover, followed by considerations of cable modelling and engagement loads, vehicle trim characteristics, low-frequency “pendular” modes, vertical-bounce dynamics, rotor-body coupling (regressing lag mode), and elastic-fuselage effects.