Flight Loads Analysis Research Articles

Usage and Flight Loads Analysis of King Airs in Aerial Firefighting Missions

Flight data of Beechcraft King Airs used as aerial supervision modules and lead aircraft by the U.S. Forest Service are analyzed. The operational conditions experienced by the airplanes are studied as well as the magnitude of the vertical loads. The airplanes are flown in four different types of missions in U.S. Forest Service operation. Data from 1853 flights and seven aircraft are presented. Spectra are shown for gust and maneuver loads, separated using the two-second rule. These are given for the entire flight for various mean sea-level altitudes. In addition, the combined loads are presented and compared to existing data and Federal Aviation Regulation 23. It is shown that these aircraft are operated well within their design envelope. It is demonstrated that, although gust loads are comparable to those outlined in Federal Aviation Regulation 23, the maneuver load frequencies far exceed those of typical airframe use. Although these results do not warrant changes to Federal Aviation Regulation 23, they highlight the need for modified airframe maintenance and inspection procedures as well as the estimated airframe fatigue life.

Framework for Flight Loads Analysis of Trajectory-Based Manoeuvres with Pilot Models

A framework is presented to allow the investigation of interactions between manual control and flight control systems for large flexible aircraft. It allows the fast simulation of particular flight test manoeuvres designed to expose unwanted interactions between the pilot and aircraft flight dynamics. It combines a trajectory generation scheme and an aeroelastic aircraft model together with pilot models to conduct flight loads analysis relevant to trajectory-based flight test manoeuvres. The ability of the framework to assess the impact of variations in pilot control characteristics on flight loads is illustrated through the simulation of two manoeuvres. The first required the pilot to align the aircraft from an offset position in minimum time and the second required avoiding an obstacle by following a four-dimensional trajectory. Pilot models representative of pilot control behavior were derived by applying a parameter identification scheme to data gathered through a series of manual control experiments. The pilot models were coupled with a nonlinear flexible aircraft model to demonstrate the effects on pilot–vehicle system frequency response due to changes in task and intersubject differences. Worst case wing loads were then obtained and compared to aircraft loads envelopes.

MSC/NASTRAN을 활용한 고세장비 유연날개 항공기의 비행하중 해석

The flight loads analysis was carried out on the aircraft with high aspect ratio flexible wings by using commercial software MSC/NASTRAN. The aerodynamic model for flight loads analysis was corrected, compared with results of the wind tunnel test. And in-house program was developed for pre and post works. In-house program enabling management of much data automatically consists of three modules: `Construction of the mass distributed model`, `Selection of critical load cases`, `Generation of external loads for structural design`. By utilizing these techniques and programs, the procedure of flight loads analysis was established for effective development of an aircraft.

Aeroelastic trim and flight loads analysis of flexible aircraft with large deformations

A method for static aeroelastic trim analysis and flight loads computation of a flexible aircraft with large deformations has been presented in this paper, which considers the geometric nonlinearity of the structure and the nonplanar effects of aerodynamics. A nonplanar vortex lattice method is used to compute the nonplanar aerodynamics. The nonlinear finite element method is introduced to consider the structural geometric nonlinearity. Moreover, the surface spline method is used for structure/aerodynamics coupling. Finally, by combining the equilibrium equations of rigid motions of the deformed aircraft, the nonlinear trim problem of the flexible aircraft is solved by iterative method. For instance, the longitudinal trim analysis of a flexible aircraft with large-aspect-ratio wings is carried out by both the nonlinear method presented and the linear method of MSC Flightloads. Results obtained by these two methods are compared, and it is indicated that the results agree with each other when the deformation is small. However, because the linear method of static aeroelastic analysis does not consider the nonplanar aerodynamic effects or structural geometric nonlinearity, it is not applicable as the deformations increase. Whereas the nonlinear method presented could solve the trim problem accurately, even the deformations are large, which makes the nonlinear method suitable for rapid and efficient analysis in engineering practice. It could be used not only in the preliminary stage but also in the detail stage of aircraft design.

ARGON을 이용한 스마트 무인기 비행하중해석

스마트 무인기 비행하중해석을 위해서는 규정과 하중조건을 준비하고, 공기력, 중량 및 구조 모델링을 수행해야 한다. 항공기 비행하중 해석시 공기력은 일반적으로 패널방법을 이용하여 산출하게 된다. 본 연구에서는 하중해석을 위해 In-house 프로그램인 ARGON을 사용하였다. ARGON은 KARI와 TsAGI가 공동 개발한 고정익 항공기 설계 프로그램으로서 비행하중, 지상하중, 플러터 및 응력해석을 지원한다. 본 논문에서는 FAR 23급 항공기인 스마트 무인기의 비행하중해석을 ARGON을 이용하여 수행하였고 그 결과를 제시하였다. For flight loads analysis of Smart UAV, applicable regulations and loads conditions should be prepared in advance, and modeling for aerodynamics, weight, and structure should be performed. Panel method is usually adopted for aircraft loads analysis to obtain aerodynamic loads. In this study, ARGON which is a multidisciplinary fixed wing aircraft design software co-developed by KARI and TsAGI was used for loads analysis. ARGON can be utilized for flutter and stress analysis as well as for flight and ground loads analysis. In this paper, flight loads analysis of Smart UAV which is a FAR 23 category airplane was performed with ARGON and the results were presented.

Identifying Slowly Varying and Turbulent Wind Features for Flight Loads Analyses

Abstract : A methodology developed to determine the spectral boundary between the slowly-varying components and the more rapidly varying, or turbulent components, of measured wind profiles is presented. Pairs of measured wind velocity versus altitude profiles from the Eastern and Western launch ranges of the United States were used to establish the vertical wavelengths which could no longer be considered slowly varying over discrete time intervals. Analyses were performed for wind pairs that were 30, 60, 90, and 120 minutes apart. The wavelength boundary between slowly-varying and turbulent wind features as a function of time interval is presented. The results of this work make it now possible to identify and extract the slowly-varying and/or turbulent wind features, as needed for a specific day-of-launch flight loads analysis, for these two launch facilities.

Refined Day-of-Launch Atmospheric Flight Loads Analysis Approach

Covers advancements in spacecraft and tactical and strategic missile systems, including subsystem design and application, mission design and analysis, materials and structures, developments in space sciences, space processing and manufacturing, space operations, and applications of space technologies to other fields.