scholarly journals Review of Modern Helicopter Constructions and an Outline of Rotorcraft Design Parameters

2021 ◽  
Vol 12 (3) ◽  
pp. 27-52
Author(s):  
Stanisław KACHEL ◽  
Robert ROGÓLSKI ◽  
Jakub KOCJAN
Keyword(s):  
Helicopter Rotor ◽  
Design Parameters ◽  
Evaluation Tool ◽  
Average Dimension ◽  
Mathematical Formulas ◽  
Observation Training

This work contains the results of a modern helicopter construction analysis. It includes the comparison of almost seventy rotorcraft constructions in terms of size in line with EASA requirements – large and small helicopters. The helicopters are also divided because of a mission purpose. The proposed division for large aircrafts is: transport, multipurpose, attack and for small aircrafts: observation, training, and utility. The aircraft construction features are described. Average dimension values of airframes and rotors are shown. Helicopter rotor arrangements are presented in terms of an operational purpose. Next, the rotorcraft design inputs are described. The mathematical formulas for design inputs are given. The ratios are calculated and gathered for the compared aircrafts. Correlation between the analysed parameters is presented on charts. Design inputs are also presented in the paper as a function of MTOW. The function trends are determined to provide an evaluation tool for helicopter designers. In addition, the parameters are presented as possible optimisation variables.

Design of composite helicopter rotor blades to meet given cross-sectional properties

2005 ◽  
Vol 109 (1100) ◽  
pp. 471-475 ◽  
Author(s):  
S. L. Lemanski ◽  
P. M. Weaver ◽  
G. F. J. Hill
Keyword(s):  
Finite Element ◽  
Objective Function ◽  
Helicopter Rotor ◽  
Design Parameters ◽  
Stochastic Methods ◽  
Element Analysis ◽  
Cross Sectional ◽  
Design Variables ◽  
Non Linear ◽  
Optimisation Methods

Abstract This paper examines the design of a composite helicopter rotor blade to meet given cross-sectional properties. As with many real-world problems, the choice of objective and design variables can lead to a problem with a non-linear and/or non-convex objective function, which would require the use of stochastic optimisation methods to find an optimum. Since the objective function is evaluated from the results of a finite element analysis of the cross section, the computational expense of using stochastic methods would be prohibitive. It is shown that by choosing appropriate simplified design variables, the problem becomes convex with respect to those design variables. This allows deterministic optimisation methods to be used, which is considerably more computationally efficient than stochastic methods. It is also shown that the design variables can be chosen such that the response of each individual cross-sectional property can be closely modelled by a linear approximation, even though the response of a single objective function to many design parameters is non-linear. The design problem may therefore be reformulated into a number of simultaneous linear equations that are easily solved by matrix methods, thus allowing an optimum to be located with the minimum number of computationally expensive finite element analyses.

scholarly journals Ergonomics Evaluation in Designed Maintainability: Case Study Using 3 DSSPP

2021 ◽  
Vol 29 (4) ◽  
pp. 309-319
Author(s):  
Kiumars Teymourian ◽  
Phillip Tretten ◽  
Dammika Seneviratne ◽  
Diego Galar
Keyword(s):  
Design Process ◽  
Sustainable Use ◽  
Well Being ◽  
Design Parameters ◽  
Work Place ◽  
Time Cost ◽  
Evaluation Tool ◽  
Human Capabilities ◽  
Prediction Program

Abstract Maintainability is one of the design parameters (reliability, availability, maintainability, and safety (RAMS)) and maintenance is needed to keep the respective design in sustainable use. At the same time, the human is involved in the form of interface and interaction in an engineered product/system designed. Ergonomics is a multi-disciplinary science that considers human capabilities and limitations in a broader sense. The objective of this paper is to integrate ergonomics into the maintainability design process in order to facilitate maintenance operation in lesser; time, cost, easier operation as well as the well-being of human who is involved. In other words, good ergonomics lead to good economics and in a broader sense, sustainability. This investigation shows that designing comfortable workplaces and lesser workload for maintenance operators will be beneficial for the maintainability design process and also improve the meantime to repair MTTR. In order to evaluate the effect of designed work-place and workload on maintainers 3 D Static Strength Prediction Program (3D SSPP) that is commonly used as an ergonomics evaluation tool in scientific studies was applied.

scholarly journals Finite Element Framework for Efficient Design of Three Dimensional Multicomponent Composite Helicopter Rotor Blade System

Eng ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 69-79
Author(s):  
Arunabha M. Roy
Keyword(s):  
Finite Element ◽  
Composite Laminates ◽  
Rotor Blade ◽  
Three Dimensional ◽  
Deformation Characteristic ◽  
Helicopter Rotor ◽  
Design Parameters ◽  
Efficient Design ◽  
Helicopter Rotor Blade ◽  
Blade System

In the present study, a three-dimensional finite element framework has been developed to model a full-scale multilaminate composite helicopter rotor blade. Tip deformation and stress behavior have been analyzed for external aerodynamic loading conditions and compared with the Abaqus FEA model. Furthermore, different parametric studies of geometric design parameters of composite laminates are studied in order to minimize tip deformation and maximize the overall efficiency of the helicopter blade. It is found that these parameters significantly influence the tip deformation characteristic and can be judiciously chosen for the efficient design of the rotor blade system.

The Design and Evaluation of a Supercritical-Speed Helicopter Power-Transmission Shaft

1967 ◽  
Vol 89 (4) ◽  
pp. 719-727 ◽  
Author(s):  
R. H. Prause ◽  
H. C. Meacham ◽  
J. E. Voorhees
Keyword(s):  
Power Transmission ◽  
Small Diameter ◽  
Helicopter Rotor ◽  
Design Parameters ◽  
Viscous Damper ◽  
Critical Speeds ◽  
The Third ◽  
Transmission Shaft ◽  
Outside Diameter ◽  
Supercritical Speed

A series of research programs with small-diameter, supercritical-speed power-transmission shafting has led to the development of design techniques for the application of one or two viscous dampers to control shaft vibrations through as many as 20 critical speeds. These techniques have been used to design a large, 338.5-in-long helicopter rotor synchronizing shaft using aluminum tubing with an outside diameter of 4.50 in. and a wall thickness of 0.12 in. A single viscous damper located 30.0 in. from one end of the shaft has been used to successfully operate the shaft through its first five critical speeds. The design parameters and experimental results for this shaft are discussed, along with a description of the application of modal balancing at the third, fourth, and fifth critical speeds.

Parametric Study of Helicopter Blade for Active Twist Control Incorporating Macro Fiber Composite Actuator

2018 ◽  
Author(s):  
Mürüvvet Sinem Sicim ◽  
Dinçer Demirci ◽  
Metin Orhan Kaya
Keyword(s):  
Rotor Blade ◽  
Fiber Composite ◽  
Load Capacity ◽  
Thermal Strain ◽  
Helicopter Rotor ◽  
Design Parameters ◽  
Skin Thickness ◽  
Helicopter Rotor Blade ◽  
Active Twist ◽  
Macro Fiber Composite

Helicopters suffer from a number of problems raised from the high vibratory loads, noise generation, load capacity limitations, forward speed limitation etc. Especially unsteady aerodynamic conditions due to the different aerodynamic environment between advised and retreating side of the rotor cause most of these problems. Researchers study on passive and active methods to eliminate negative effects of aerodynamic loads. Nowadays, active methods such as Higher Harmonic Control (HHC), Individual Blade Control (IBC), Active Control of Structural Response (ACSR), Active Twist Blade (ATB), and Active Trailing-edge Flap (ATF) gain importance to vibration and noise reduction. In this paper, strain-induced blade twist control is studied integrated by Macro Fiber Composite (MFC) actuator. 3D model is presented to analyze the twisting of a morph and bimorph helicopter rotor blade comprising MFC actuator which is generally applied vibration suppression, shape control and health monitoring. The helicopter rotor blade is modeling with NACA23012 airfoil type and consists of D-spar made of unidirectional fiberglass, ±45° Glass Fiber Reinforced Polymer (GFRP) and foam core. Two-way fluid-structure interaction (FSI) method is used to simulate loop between fluid flow and physical structure to enable the behavior of the complex system. To develop piezoelectric effects, thermal strain analogy based on the similarities between thermal and piezo strains. The optimization results are obtained to show the influence of different design parameters such as web length, spar circular fitting, MFC chord length on active twist control. Also, skin thickness, spar thickness, web thickness are used to optimization parameters to illustrate effects on torsion angle by applying response surface methodology. Selection of correct design parameters can then be determined based on this system results.

scholarly journals Control of a hybrid helicopter with wings

2017 ◽  
Vol 9 (3) ◽  
pp. 209-217 ◽  
Author(s):  
Christophe De Wagter ◽  
Ewoud JJ Smeur
Keyword(s):  
Vehicle Dynamics ◽  
Large Range ◽  
Hybrid Vehicle ◽  
Helicopter Rotor ◽  
Design Parameters ◽  
Theoretic Model ◽  
Forward Flight ◽  
Rotor Wing ◽  
Hover Flight ◽  
Wing Interaction

This work investigates the design parameters and their consequences in the control of a helicopter rotor combined with a pair of fixed wings. This hybrid vehicle has a light and aerodynamically efficient rotor with a large range of pitch angles to enable both hover and forward flight. Because of the light stiff rotor and heavy wings, the hybrid vehicle exhibits couplings between the roll and pitch axes during hover flight. The rotor-wing interaction depends on a lot of parameters. In this article, we utilize a simplified theoretic model and simulations in order to gain insight in the effect of these parameters on the vehicle dynamics. Finally, a controller is designed that compensates undesired coupling between pitch and roll.

scholarly journals How do gloves affect cutaneous sensibility in medical practice? Two new applied tests

2016 ◽  
Vol 231 (1) ◽  
pp. 28-39 ◽  
Author(s):  
Peter Mylon ◽  
Matt J Carré ◽  
Nicolas Martin ◽  
Roger Lewis
Keyword(s):  
Test Procedure ◽  
Neurological Impairment ◽  
Design Parameters ◽  
Small Scale ◽  
Evaluation Tool ◽  
Aptitude Testing ◽  
Latex Gloves ◽  
Material Stiffness ◽  
Test Orientation ◽  
Medical Examinations

In order to quantify the effect of medical gloves on tactile performance, two new Simulated Medical Examination Tactile Tests (SMETT) have been developed to replicate the tactile and haptic ability required in medical examinations: the ‘Bumps’ test and the ‘Princess and the Pea’ (P&P) test. A pilot study was carried out using 30–40 subjects for each test in order to investigate the suitability of the tests for medical glove evaluation. Tests were performed with latex and nitrile examination gloves and without gloves. Following the tests, small-scale studies were carried out to investigate the effect of various design parameters, such as material stiffness and tactile exploration method. In the ‘Bumps’ test, subjects performed significantly better in the ungloved condition, and there were ‘almost significant’ differences between the gloves, with the thinner latex gloves performing better than the thicker nitrile gloves. Both finger orientation and surface lubrication were found to have a significant effect on results, indicating that these need to be clearly defined in the test procedure. In the ‘P&P’ test, no significant effect of hand condition was found, suggesting that haptic sensing is less affected by medical gloves than cutaneous sensibility. Other factors such as material stiffness, technique and test orientation had a more significant effect. The SMETT ‘Bumps’ test has potential as a clinical manual performance evaluation tool and may be used to evaluate the relative effects of different gloves. The SMETT ‘P&P’ test is a valid measure of haptic or tactile performance, but should not be used in glove evaluation. Both tests could have further applications, such as in the assessment of neurological impairment or aptitude testing for potential surgeons.

scholarly journals Chord Morphing for Helicopter Rotor Blades

2019 ◽  
Author(s):  
Johannes Riemenschneider ◽  
Christoph Balzarek ◽  
Berend G. van der Wall ◽  
Rohin Kumar Majeti
Keyword(s):  
Chord Length ◽  
Rotor Blades ◽  
Helicopter Rotor ◽  
Design Parameters ◽  
Forward Flight ◽  
Helicopter Rotors ◽  
Helicopter Rotor Blades ◽  
Helicopter Rotor Blade ◽  
Structural Concept ◽  
Final Design

Abstract Since helicopter rotors have different demands from different flight stats, the final design is always a compromise between flight stats such as hover and fast forward flight. Two of the design parameters are twist and chord length. This paper is giving some reasoning from rotor simulations on what twist and chord length should look like in order to increase performance in hover or forward flight. The result is, that the inboard chord length should be much larger for hover than for forward flight. This paper is presenting a structural concept, that can enable a helicopter rotor blade to change its chord length.

The influence of confocal microscope design on imaging performance

1993 ◽  
Vol 51 ◽  
pp. 144-145
Author(s):  
C J R Sheppard
Keyword(s):  
Image Quality ◽  
Fluorescence Imaging ◽  
Confocal Microscope ◽  
Industrial Applications ◽  
Three Dimensions ◽  
Design Parameters ◽  
Weak Signals ◽  
Size And Shape ◽  
Imaging Performance ◽  
Fundamental Limitation

The confocal microscope is now widely used in both biomedical and industrial applications for imaging, in three dimensions, objects with appreciable depth. There are now a range of different microscopes on the market, which have adopted a variety of different designs. The aim of this paper is to explore the effects on imaging performance of design parameters including the method of scanning, the type of detector, and the size and shape of the confocal aperture.It is becoming apparent that there is no such thing as an ideal confocal microscope: all systems have limitations and the best compromise depends on what the microscope is used for and how it is used. The most important compromise at present is between image quality and speed of scanning, which is particularly apparent when imaging with very weak signals. If great speed is not of importance, then the fundamental limitation for fluorescence imaging is the detection of sufficient numbers of photons before the fluorochrome bleaches.

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