VIBRATIONS OF A HELICOPTER ROTOR SYSTEM AND FUSELAGE INDUCED BY THE MAIN ROTOR BLADES IN FLIGHT

1953 ◽  
Author(s):  
MORRIS MORDUCHOW ◽  
SHAO W. YUAN ◽  
H. REISSNER
Keyword(s):  
Rotor System ◽  
Rotor Blades ◽  
Helicopter Rotor ◽  
Main Rotor

Vibrations of a Helicopter Rotor-Fuselage System Induced by the Main Rotor Blades in Flight

1955 ◽  
Vol 22 (3) ◽  
pp. 355-360
Author(s):  
M. Morduchow ◽  
S. W. Yuan ◽  
H. Reissner
Keyword(s):  
Theoretical Analysis ◽  
Natural Frequencies ◽  
Rotor Blades ◽  
Helicopter Rotor ◽  
Simplified Model ◽  
Main Rotor ◽  
Numerical Examples ◽  
The Masses

Abstract Based on a simplified model of the hub-fuselage structure, a theoretical analysis is made of the response of the hub and fuselage of a helicopter in flight to harmonic forces transmitted by the rotor blades to the hub both in, and normal to, the plane of rotation. The assumed structure is in the form of a plane framework with masses concentrated at the joints. Simple expressions are derived for the vibration amplitudes of the mass points as functions of the masses and natural frequencies of the hub and the fuselage. The pertinent nondimensional parameters are determined, and simple explicit conditions of resonance are derived. Numerical examples are given to illustrate the results.

scholarly journals Some practical issues in the computational design of airfoils for the helicopter main rotor blades

2004 ◽  
Vol 31 (3-4) ◽  
pp. 281-315
Author(s):  
Ivan Kostic
Keyword(s):  
Computational Design ◽  
Rotor Blades ◽  
Helicopter Rotor ◽  
Design Stage ◽  
Main Rotor ◽  
Moment Coefficient ◽  
Plastic Composites ◽  
Zero Moment ◽  
The Moment ◽  
Helicopter Main Rotor

Very important requirement for the helicopter rotor airfoils is zero, or nearly zero moment coefficient about the aerodynamic center. Unlike the old technologies used for metal blades, modern production involving application of plastic composites has imposed the necessity of adding a flat tab extension to the blade trailing edge, thus changing the original airfoil shape. Using computer program TRANPRO, the author has developed and verified an algorithm for numerical analysis in this design stage, applied it on asymmetrical reflex camber airfoils, determined the influence of angular tab positioning on the moment coefficient value and redesigned some existing airfoils to include properly positioned tabs that satisfy very low moment coefficient requirement. .

scholarly journals GUI FOR VIBRATION PREDICTIONS DURING RTB OF A SERVICED HELICOPTER

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Kothara Srinivasa Rao ◽  
A.Gopala Krishna
Keyword(s):  
Linear Regression ◽  
Multiple Linear Regression ◽  
Regression Models ◽  
Research Work ◽  
Rotor System ◽  
Rotor Blades ◽  
Main Rotor ◽  
Out Of Plane ◽  
The Difference ◽  
Flight Regimes

Vibrations on helicopter induced in Main Rotor System and Tail Rotor System due to in plane unbalanced masses and out of plane rotation of rotor blades. Rotor Track and Balance (RTB) of helicopter is performed to reduce vibrations of helicopter. Number of vibration flights will increase if RTB is not optimised. Main Rotor and Tail Rotor vibrations can be reduced by predicting the vibrations prior to flight using Multiple Linear Regression and Analysis of Variance (MLR & ANOVA). The Inputs for the Multiple Linear Regression would be in terms of mass changes, track changes and tab changes based on established sensitivities of these Inputs and cross sensitivities between them. The outputs are vibration changes of Main Rotor / Tail Rotor. Change in vibrations is the difference between the vibration values of two successive flights / ground runs. For Main Rotor, there are 12 inputs to adjust 2 outputs (MR Lateral and MR Vertical), for Tail Rotor, there are 8 inputs to adjust 2 outputs (TR Radial and TR Axial) for satisfactory vibrations during ground run, HOGE and two steady speed forward flight regimes. In this Research work, three types of Regression Models for Main Rotor System and Two types of Regression Models for Tail Rotor System were made to predict the vibrations of helicopter prior to ground run or flight. The Regression Coefficients were evaluated using MatLab and models were generated. ANOVA is performed for regression models and found satisfactory. The Coefficient of Regression (Multiple-R / R 2 ) values obtained are more than 0.9. The results of the regression indicated that the model was a significant predictor of vibration changes. Graphical User Interface (GUI) using Regression Models is made for vibration predictions of Main Rotor and Tail Rotor Vibrations of Serviced helicopter. This research work recommends for the implementation of Multiple Linear Regression and its applications for vibration predictions of Serviced helicopters to reduce vibration fl

Circulation Control Span-Wise Blowing Location Optimization for a Helicopter Rotor Blade

2010 ◽  
Author(s):  
Alan M. Didion ◽  
Jonathan Kweder ◽  
Mary Ann Clarke ◽  
James E. Smith
Keyword(s):  
Stress Reduction ◽  
Rotor Blades ◽  
Helicopter Rotor ◽  
Base Line ◽  
Control Technology ◽  
Circulation Control ◽  
High Lift ◽  
Location Optimization ◽  
Helicopter Rotor Blades ◽  
Length Reduction

Circulation control technology has proven itself useful in the area of short take-off and landing (STOL) fixed wing aircraft by decreasing landing and takeoff distances, increasing maneuverability and lift at lower speeds. The application of circulation control technology to vertical take-off and landing (VTOL) rotorcraft could also prove quite beneficial. Successful adaptation to helicopter rotor blades is currently believed to yield benefits such as increased lift, increased payload capacity, increased maneuverability, reduction in rotor diameter and a reduction in noise. Above all, the addition of circulation control to rotorcraft as controlled by an on-board computer could provide the helicopter with pitch control as well as compensate for asymmetrical lift profiles from forward flight without need for a swashplate. There are an infinite number of blowing slot configurations, each with separate benefits and drawbacks. This study has identified three specific types of these configurations. The high lift configuration would be beneficial in instances where such power is needed for crew and cargo, little stress reduction is offered over the base line configuration. The stress reduction configuration on the other hand, however, offers little extra lift but much in the way of increased rotor lifespan and shorter rotor length. Finally, the middle balanced configuration offers a middle ground between the two extremes. With this configuration, the helicopter benefits in all categories of lift, stress reduction and blade length reduction.

scholarly journals ACTIVE TWIST OF MODEL ROTOR BLADES WITH D-SPAR DESIGN

Transport ◽  
2007 ◽  
Vol 22 (1) ◽  
pp. 38-44 ◽  
Author(s):  
Andrejs Kovalovs ◽  
Evgeny Barkanov ◽  
Sergejs Gluhihs
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Rotor Blade ◽  
Element Model ◽  
Rotor Blades ◽  
Helicopter Rotor ◽  
3D Finite Element ◽  
3D Finite Element Model ◽  
Helicopter Rotor Blade ◽  
Active Twist

The design methodology based on the planning of experiments and response surface technique has been developed for an optimum placement of Macro Fiber Composite (MFC) actuators in the helicopter rotor blades. The baseline helicopter rotor blade consists of D‐spar made of UD GFRP, skin made of +450/‐450 GFRP, foam core, MFC actuators placement on the skin and balance weight. 3D finite element model of the rotor blade has been built by ANSYS, where the rotor blade skin and spar “moustaches” are modeled by the linear layered structural shell elements SHELL99, and the spar and foam ‐ by 3D 20‐node structural solid elements SOLID 186. The thermal analyses of 3D finite element model have been developed to investigate an active twist of the helicopter rotor blade. Strain analogy between piezoelectric strains and thermally induced strains is used to model piezoelectric effects. The optimisation results have been obtained for design solutions, connected with the application of active materials, and checked by the finite element calculations.

Sign in / Sign up

Export Citation Format

Share Document