Results 81 to 90 of about 30,676 (232)

Results of the flight noise measurement program using a standard and modified SH-3A helicopter [PDF]

A field noise measurement program has been conducted using both a standard SH-3A helicopter and an SH-3A helicopter modified to reduce external noise levels.
Henderson, H. R., Hilton, D. A., Pegg, R. J.   +2 more
core   +1 more source

Lifting and Transport of Martian Dust by the Ingenuity Helicopter Rotor Downwash as Observed by High-Speed Imaging From the Perseverance Rover. [PDF]

J Geophys Res Planets, 2022
Lemmon MT, Lorenz RD, Rabinovitch J, Newman CE, Williams NR, Sullivan R, Golombek MP, Bell JF, Maki JN, Vicente-Retortillo A.   +9 more
europepmc   +1 more source

Calculated Hovering Helicopter Flight Dynamics with a Circulation Controlled Rotor [PDF]

The influence of the rotor blowing coefficient on the calculated roots of the longitudinal and lateral motion was examined for a range of values of the rotor lift and the blade flap frequency.
Chopra, I., Johnson, W.
core   +1 more source

Helicopter low-speed yaw control [PDF]

, 1993
A system for improving yaw control at low speeds consists of one strake placed on the upper portion of the fuselage facing the retreating rotor blade and another strake placed on the lower portion of the fuselage facing the advancing rotor blade.
Crowell, Cynthia A., Kelley, Henry L., Wilson, John C.   +2 more
core   +1 more source

Design of Unmanned Helicopter Distributed Electric Tail Rotor Controller Based on Improved Active Disturbance Rejection Control

IEEE Access
In response to the critical implications of single tail rotor failures in unmanned helicopters, this study proposes a distributed electric tail rotor yaw channel controller that employs Active Disturbance Rejection Control (ADRC) techniques.
Qing-Xin Zhang, Yun-Feng Ji, Feng Wang, Lei Pei, Zheng-Ming Cha   +4 more
doaj   +1 more source

CALCULATED RESEARCH OF INFLUENCE OF HELICOPTER MAIN ROTORS GEOMETRY ON THE EFFICIENCY IN HOVER MODE BASED ON THE NONLINEAR VORTEX MODEL

Научный вестник МГТУ ГА, 2018
The efficiency of the helicopter main rotor in the hover mode is very important, because this mode essentially determines the performance characteristics of the helicopter.
Y. M. Ignatkin, P. V. Makeev, A. I. Shomov   +2 more
doaj   +1 more source

Hysteresis Compensation for a Piezoelectric Actuator of Active Helicopter Rotor Using Compound Control. [PDF]

Micromachines (Basel), 2021
Zhou J, Dong L, Yang W.
europepmc   +1 more source

Main rotor-tail rotor intraction and its implications for helicopter directional control [PDF]

, 2008
Aerodynamic interference between the main and tail rotor can have a strong negative influence on the flight mechanics of a conventional helicopter. Significant unsteadiness in the tail rotor loading is encountered under certain flight conditions, but the
Brown, R.E., Fletcher, Timothy M.
core   +1 more source

A Case of Penetrating Head Wound Due to Helicopter Rotor Blade Injury in a 34-Year-Old Naval Helicopter Pilot Who Returned to Active Service 5 Years Later. [PDF]

Am J Case Rep, 2021
Hsieh CC, Chan PY, Liou LR, Chen YK, Tsao MJ, Chen LF, Lin KH.   +6 more
europepmc   +1 more source

Results of the noise measurement program on a standard and modified OH-6A helicopter [PDF]

A field noise measurement program has been conducted on a standard OH-6A helicopter and one that had been modified by reducing the rotor speed, altering rotor tip shape, and treating the engine exhaust and inlet to reduce the external noise levels.
Henderson, H. R., Hilton, D. A., Peegg, R. J.   +2 more
core   +1 more source