State-of-the-art tilt-rotor flight mechanics models appear to be inadequate in predicting the flight dynamics behavior across the entire flight envelope due to a lack of experimental data suggesting the need for more generic models. This paper presents a middle ground between model flexibility (genericity) and accuracy. For this purpose a generic 7-degrees-of-freedom tilt-rotor flight mechanics model is derived analytically. A novel ordering scheme is employed ensuring a bounded expression simplification error which is not found in existing tilt-rotor models. The research highlights the effects of the tiltable nacelle on the rotor analytical expressions and static flight mechanics. The model is validated against the XV-15 implementation of the NASA GTRS model showing promising overlap. It is concluded that the tiltable nacelle mainly affects the rotor expressions through the velocity experienced by the rotor hub and blade element, and that the nacelle tilt rate and acceleration are considered significant contributors to many rotor expressions. It is also shown that the nacelle tilt rate has an observable effect on handling and performance. Terms unique to tiltable proprotors are shown to exist, most notably the Coriolis effect of the nacelle tilt on the flapping dynamics. Several assumptions common in tilt-rotor modeling are also shown to be grossly violated. The future recommendation is to incorporate more sophisticated wing, control surface, and fuselage models, while the rotor model should include disk tilt and inflow dynamics, and a non-uniform inflow distribution.

The Unmanned Aerial Vehicle (UAV) market is growing, as the field of application becomes increasingly diverse. Various missions performed by UAVs such as transport, surveillance and monitoring missions can be less challenging and more efficient compared to missions carried out by manned aircraft. The new design principle of combining a helicopter and a conventional aircraft has been proven to be prominent, as it allows a UAV to be versatile and have capability of being retrofitted to different mission profiles; these Hybrid UAVs are able to operate at broader conditions, as they can take-off and land without a runway and have a horizontal flight performance of a conventional aircraft.