Rotor Downwash Velocities about the UH-1M Helicopter - Flight Test Measurements and Theoretical Calculations

1975 ◽  
Author(s):  
B. Z. Jenkins ◽  
A. S. Marks
Keyword(s):  
Theoretical Calculations ◽  
Flight Test ◽  
Helicopter Flight

scholarly journals Improving a real-time helicopter simulator model with linear input filters

2021 ◽  
Author(s):  
Pavle Šćepanović ◽  
Frederik A. Döring
Keyword(s):  
Feedback Control ◽  
Time Domain ◽  
Flight Test ◽  
Flight Mechanics ◽  
Mean Square ◽  
Qualification Test ◽  
Model Inversion ◽  
Helicopter Flight ◽  
The Time Domain ◽  
Mean Square Errors

AbstractFor a broad range of applications, flight mechanics simulator models have to accurately predict the aircraft dynamics. However, the development and improvement of such models is a difficult and time consuming process. This is especially true for helicopters. In this paper, two rapidly applicable and implementable methods to derive linear input filters that improve the simulator model are presented. The first method is based on model inversion, the second on feedback control. Both methods are evaluated in the time domain, compared to recorded helicopter flight test data, and assessed based on root mean square errors and the Qualification Test Guide bounds. The best results were achieved when using the first method.

Distributed Turbulence Model with Rigorous Spatial Cross-Correlation for Simulation of Helicopter Flight in Atmospheric Turbulence

2019 ◽  
Vol 64 (4) ◽  
pp. 1-13
Author(s):  
Honglei Ji ◽  
Renliang Chen ◽  
Pan Li
Keyword(s):  
Atmospheric Turbulence ◽  
Turbulence Model ◽  
Cross Correlation ◽  
Turbulence Models ◽  
Flight Test ◽  
Longitudinal Direction ◽  
Flight Simulation ◽  
Quality Analysis ◽  
Frequency Range ◽  
Helicopter Flight

This paper presents a distributed turbulence model with rigorous spatial cross-correlation for helicopter flight simulation in atmospheric turbulence and for future handling-quality analysis. First, digital filters with longitudinal correlations of the von Kármán turbulence are developed to generate discrete turbulence velocity components. Meanwhile, transverse turbulence correlations are considered by relating the filters in different positions with mathematically rigorous spatial cross-correlation. Then, the distributions of the related filters on the transverse plane in front of helicopter and their velocity components in the longitudinal direction of airspeed, as well as turbulence models of helicopter aerodynamic surfaces, are established. Finally, a flight dynamics model coupled with the turbulence model is developed and validated against the flight-test data. The proposed model can achieve accurate real-time simulations of helicopter response to atmospheric turbulence in the frequency range of interest of handling qualities. The effect of transverse turbulence correlations on helicopter frequency response is also analyzed. The results show that the simulation model regardless of transverse turbulence correlations would aggravate the "rotor-to-body attenuation" effect of the main rotor and therefore underpredict the helicopter roll, pitch, and heave rate responses to atmospheric turbulence in the frequency range of interest.

Helicopter flight simulation trim in the coordinated turn with the hybrid genetic algorithm

2017 ◽  
Vol 233 (3) ◽  
pp. 1159-1168 ◽  
Author(s):  
Wei Wang ◽  
Dongsheng Li ◽  
Chun Liu
Keyword(s):  
Genetic Algorithm ◽  
Hybrid Genetic Algorithm ◽  
Flight Test ◽  
Flight Simulation ◽  
Control Vector ◽  
Experimental Platform ◽  
Helicopter Flight ◽  
Quasi Newton ◽  
General Method ◽  
Good Agreement

Helicopter trim models are multivariate nonlinear equations and it is difficult to determine these initial trim points comparable to flight conditions. To solve this question, a hybrid genetic algorithm is presented in this paper, that combines the quick convergence ability of the quasi-Newton method and the advantages of genetic algorithm, such as global convergence. The trim control vector and the constraint conditions were established in the coordinated-turn based on the helicopter flight dynamic model. The coordinated turn flight of a UH-60 A helicopter was taken as an example to simulate on the experimental platform. Comparisons were made between the trim results and flight test data and there is a good agreement among them, and the efficiency of the algorithm presented is verified. It is a general method that can be applied to trim the helicopter of different flight conditions.

Development of Fly Neighborly helicopter model specific operational noise abatement guidance from acoustic flight test data

2021 ◽  
Vol 263 (1) ◽  
pp. 5671-5677
Author(s):  
Juliet Page ◽  
Amanda Rapoza ◽  
Eric Jacobs
Keyword(s):  
Test Data ◽  
Noise Exposure ◽  
Flight Test ◽  
Operating Conditions ◽  
Noise Emission ◽  
Noise Abatement ◽  
Local Conditions ◽  
Planning Stage ◽  
Helicopter Flight ◽  
Us Government

Improved helicopter noise abatement guidance has been developed based on acoustic test data acquired by NASA, FAA and Volpe in support of the Helicopter Association International (HAI)'s Fly Neighborly Program. This higher fidelity material was developed to supplement previous training programs based on pilot and operator feedback. The manner of presentation allows pilots to readily interpret the directional noise emission of their vehicle at different operating conditions. Flight path, airspeed, approach descent rate, and deceleration rate can be assessed to optimize flight patterns both during the pre-flight planning stage and in real time during flight operations in response to local conditions and events. The resultant sound directivity would be displayed as colored noise exposure contours overlaid onto a map of the area in the vicinity of the helicopter. New Fly Neighborly training modules have been developed utilizing directional operational noise plots based on Volpe's Advanced Acoustic Model (AAM) modeling with empirical sound sphere data from dedicated US Government helicopter flight tests. This paper will describe the acoustic analyses and will present the updated noise guidance for the AS350, AS365, AW139, Bell 205, Bell 206, Bell 407, R-44, R-66 and S-76D helicopters.

Evaluation of ILS Radio Anomalies by Helicopter Flight Test and Numerical Analysis

2002 ◽  
Vol 47 (3) ◽  
pp. 169-177
Author(s):  
Naoki Matayoshi ◽  
Yoshinori Okuno ◽  
Hisashi Yokoyama
Keyword(s):  
Numerical Analysis ◽  
Flight Test ◽  
Helicopter Flight

Understanding the Effect of Rotor-to-Rotor Interference on CH-47D Helicopter Dynamics

2021 ◽  
Author(s):  
Feyyaz Guner ◽  
David G. Miller ◽  
J. V. R. Prasad
Keyword(s):  
Flight Control ◽  
Influence Factors ◽  
Flight Test ◽  
Flight Simulation ◽  
Flight Control System ◽  
Pressure Potential ◽  
Handling Qualities ◽  
Helicopter Flight ◽  
Lateral Inflow ◽  
Lateral Axis

During the development of the Boeing CH-47D helicopter flight simulation model, test pilots reported mismatch between the flight simulator results and flight test data of the hover and low-speed lateral axis handling qualities, especially for the case without the automatic flight control system. In addressing the observed mismatch, the gains of the longitudinal and lateral components of the inflow model were selected to be significantly higher than their theoretical values. In this study, a detailed understanding of the rotor-to-rotor inflow interference is pursued using a recently developed multi-rotor pressure potential superposition inflow model. It is shown that the coupling between the inflow gradients of individual rotors exists in a tandem rotor, which can be approximated by using higher values for the longitudinal and lateral inflow gains of individual rotors. Further, it is shown that the need for empirical tuning of aerodynamic hub moment influence factors can be eliminated by properly accounting for the rotor-to-rotor interference in the inflow model.

scholarly journals Correlation of SA349/2 Helicopter Flight Test Data with a Comprehensive Rotorcraft Model

1988 ◽  
Vol 33 (2) ◽  
pp. 31-42 ◽  
Author(s):  
Gloria K. Yamauchi ◽  
Ruth M. Heffernan ◽  
Michel Gaubert
Keyword(s):  
Test Data ◽  
Flight Test ◽  
Helicopter Flight
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