This paper presents a study on the effect of wake modeling on the prediction of the off-axis response to pilot inputs for a hingeless and an articulated rotor helicopter, including a comparison with flight test data. The free wake model can capture geometry changes due to maneuvering flight. The prediction of the response to pilot inputs improves only slightly; in particular, the off-axis respo...

The compression of a crystalline material under hydrostatic pressure always results in a reduction in volume of the solid, with the observed reduction typically occurring in all crystallographic cell parameters. However, there are a number of exceptional materials that have been shown to expand in a specific direction upon hydrostatic compression while maintaining a positive volume compression....

The efficiency and operating envelope of rotorcraft are constrained by the speed rotor. Most helicopters operate with a constant rotor speed. Varying based on condition could significantly improve rotor's performance. In this study, hingeless model elastic blades is built-in DYMORE to study various aspects variable technology. modeled as one-dimensional beams using state-of-the-art beam theory ...

This paper describes the development and validation of a high fidelity simulation model of the Bell-412 in the FLIGHTLAB environment for handling qualities and flight control investigations. The base-line rotor model features a rigid, articulated blade-element formulation with flap and lag degrees of freedom. The spring strengths and locations are chosen to match the first flap and lag frequenc...

Concise Perspective and Previous Surveys W HEN reviewing research in rotary-wing aeroelasticity (RWA), it is important to mention a few historical facts. The Wright brothers flew in 1903, and Sikorsky built and started flying the first operational helicopter, the R-4 or (VS-316), in 1942. The R-4 was a three-bladed helicopter with a rotor diameter of 11.6 m and was powered by a 185-hp engine. T...