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General Statements
Published in Pylyp Volodin, Blade Element Rotor Theory, 2023
A rotor system is defined here as the combination of rotary wings (blades) that generate the aerodynamic lift forces in order to: support the weight of an aircraft in a flight; counteract the aerodynamic drag of the aircraft at forward flight; and control over the aircraft motion. A rotorcraft is defined here as a heavier-than-air aircraft which uses such a rotor system to perform a flight in an airspace. Generally, a rotor system transforms energy of a rotorcraft engine into energy required for a rotorcraft flight in an airspace. It is assumed hereafter that a rotor system has defined upper and below sides; an engine of a rotorcraft is usually located below the rotor system.
Unmanned Aircraft Subsystem Integration
Published in R. Kurt Barnhart, Douglas M. Marshall, Eric J. Shappee, Introduction to Unmanned Aircraft Systems, 2021
UAS-specific actions at this phase include determining the type of aircraft necessary. The aircraft type is based primarily on range, maneuverability, lifting capacity, and costs. With hundreds to thousands of airframes to choose from, many times there are several viable options and the best fit typically comes down to a cost versus benefit comparison. General guidelines are that fixed-wing aircraft give longer duration flights that travel greater distances, but lack the maneuverability of rotorcraft. Rotorcraft allow for fixed location hovering and station keeping, but lack the flight efficiency of fixed-wing aircraft. In the past, most UAS were fixed-wing aircraft, but more recent advances in electronics miniaturization and battery developments have made multirotor aircraft the most common UAS in use today.
UAS Sensing: Theory and Practice
Published in Douglas M. Marshall, R. Kurt Barnhart, Eric Shappee, Michael Most, Introduction to Unmanned Aircraft Systems, 2016
Rotorcraft, or rotor wing aircraft, use spinning wings as their primary source of lift. These take the form of propellers, similar to the ones used to generate motion in the fixed-wing and buoyant aircraft, the chief difference being these are designed to lift the aircraft’s entire weight and control it in flight. Because the spinning blades are used to generate lift, the aircraft is capable of vertical takeoff and landing (VTOL). There are two general types of rotorcraft, single rotor and multi-rotor. The single rotor, what we grew up calling helicopters, use a single main lift rotor to both lift and control the vehicle. The single rotor lift system is marked by complicated mechanical linkages that allow for the adjustment of blade pitch in both the cyclic and collective senses, which allows the vehicle to pitch and roll while varying the overall amount of lift generated. To counteract the single lift rotor’s torque, they also utilize a much smaller tail rotor, the speed of which is coupled with the lift rotor speed and enables the aircraft to yaw on command.
Helicopter Pilots Synchronize Their Altitude with Ship Heave to Minimize Energy When Landing on a Ship’s Deck
Published in The International Journal of Aerospace Psychology, 2021
Mathieu Thomas, José M. Pereira Figueira, Julien R Serres, Thomas Rakotomamonjy, Franck Ruffier, Antoine HP Morice
The virtual world comprised a skydome above an infinite sea surface animated with realistic and configurable wave motions. A 3D ship model (Lafayette class frigate, 3,000 tons) was animated along the 6 degrees of freedom according to the roughness of the sea, wind force and direction according to a frequential model called Response Amplitude Operator (Journée & Massie, 2001; Techet, 2005), built from experimental at-sea measurements of the deck movement of the Lafayette Class frigate and provided by Naval Group. Finally, the simulator reproduced in real time with great detail the flight dynamics of an 11-ton cargo class rotorcraft through the highly realistic Helicopter Overall Simulation Code (Benoit et al., 2000), including detailed models for the various parts of the helicopter (rotor, blades, fuselage) as well as the interactions between them, the influence of external physical variables such as wind turbulences or the airwake when flying close to a ship structure. The airwake is modeled with a spatially non-uniformly distributed mean disturbance derived from data of wind tunnels obtained with a generic frigate model. The airwake directly affected the helicopter center of gravity.
Hybrid composite shaft of High-Speed Rotor-Bearing System - A rotor dynamics preview
Published in Mechanics Based Design of Structures and Machines, 2021
Thimothy Harold Gonsalves, Mohan Kumar Garje Channabasappa, Ramesh Motagondanahalli Rangarasaiah
Composite material has been one of the most researched materials in the last two to three decades for its excellent material properties. The potential use of composite material in the automotive and helicopter tail rotor drive shafts are established based on the extensive theoretical and experimental investigations. The prominent investigations of Zinberg and Symonds (1970), Singh and Gupta (1996), Hajianmaleki and Qatu (2012) and others used equivalent modulus beam theory (EMBT), layer-wise beam theory (LBT), first order shear deformation beam theory (FSDBT), etc., to perform the dynamic study of rotating composite shaft. The results of these investigations facilitated many automotive drive shaft and rotorcraft tail rotor shaft applications to use composite material to increase the shaft bending stiffness to push the bending natural frequency above the operating speeds.
Preliminary design procedure for large wind turbine blades based on the classical lamination theory
Published in Advanced Composite Materials, 2021
In the meantime, with respect to the structural design of a blade, many studies have been conducted for helicopters [7] and aeronautical engineering applications [8] involving structural optimization. Lim, et al. [9] developed a rotor optimization framework for a compound rotorcraft with a lift offset using a multilevel optimization approach. In the study, a high-speed forward flight performance and weight reduction of the rotor were examined via one-dimensional beam analysis. Friedmann, et al. [10] examined the compatibility between the composite beam cross-sectional analysis, based on the variational asymptotic approach, and a helicopter rotor blade, which was part of a comprehensive rotorcraft analysis. Kovalovs, et al. [11] performed numerical optimization of a helicopter rotor blade design for active twist control, based on the planning of experiments and a response surface technique, for an optimal design of active rotor blades.