Model Flight Test Research Articles

Research on key technologies of scaled model flight testing

The scaled model flight test is one of the three major technical paths of aerodynamic research, which can be used to study and verify the aerodynamic characteristics, danger boundary, new layout, and new technology of the prototype, with the advantages of short cycle, lower risk, and lower cost. Due to different experimental research purposes, there are different design ideas and schemes for scaled models. With the technological development of power systems such as microturbine engines and electric ducted fans, the scaled model has experienced the stages of non-powered drop flight, rocket-assisted flight, and power-driven free flight. In this paper, two scaled verification models are introduced, the similarity criteria of the scaled model are analyzed, the selection of micro engine is carried out, the ground test methods such as fuel consumption test and moment of inertia test are summarized, some test subjects and results are presented, and the key technologies of the flight test of the scaled model are summarized. The flight test results show that the test method can accurately reflect the aerodynamic characteristics and flight performance of the prototype.

Analysis of Cold/Hot Spot Effect in Flight Test Heat Flux Measurement

In model flight tests, the cold/hot spot effect often occurs due to the difference in thermal response between the heat flux sensor and surrounding thermal protection materials, which affects the heat flux measurement. In severe cases, the measurement deviation may even exceed 100%. This article analyzes the flight data of the space model flight test MF-1 and finds that there is a significant hot spot effect. This paper reproduces the temperature measurement process of MF-1 thin-skin structure along the trajectory through aerodynamic thermal/heat transfer coupling calculations. The difference between the flight data and the coupling calculation results is compared and analyzed. Based on the flight test of MF-1, the formation mechanism of the cold/hot spot effect and its impact on wall heat flux are studied. It is found that local temperature discontinuities can generate an additional wall-normal velocity near the wall, which will generate an additional wall-normal convective heat transfer, further increasing the measurement deviation of wall heat flux. The research results of this paper have important guiding significance for the development of heat flux sensors for aerospace model flight tests and correctly conducting heat flux measurements.

Synchronous playback technology of airborne network video based on RTP

In the flight test, the airborne video data is an important part of the flight test data. In order to solve the problem of synchronous playback of multiple channels of airborne network video data, a synchronous playback scheme of multiple channels of airborne network video data based on the RTP/RTCP protocol is proposed. The network video data streaming and preprocessing mechanism are used in this paper. Firstly, by identifying the data packets, the network video data packets are extracted from the data recorded on the airborne. Then, after unpacking and time calculation of the RTP-encapsulated H.264 video data, it uses FFmpeg’s good decoding capabilities to decode a frame of image, and uses SDL’s excellent video performance to display YUV data. The synchronization mechanism based on timestamp is adopted to realize the fast synchronized playback of multiple airborne network videos. The software adopts modular and multi-threaded design ideas to improve processing efficiency and ensure functional scalability. At present, the system has been successfully applied to the simultaneous playback of multi-channel airborne network video. The actual application effect shows that the system works stably and can effectively improve the efficiency of model flight tests.

Airborne Multi-channel Video Synchronization Playback Technology Based on C/S Mode

In the flight test, the airborne video data is an important part of the flight test data. At present, the airborne recorded video data is an independent M2T file, and the existing video playback software can only play back a single video file. In order to solve the problem of synchronous playback of airborne multi-channel video data, a multi-channel video synchronous playback technology based on C/S mode is proposed. The server performs video file reading control, and the client performs video decoding and display. Firstly, the basic concept of FFMPEG is introduced. Then the overall design of the system is discussed. The design and implementation of the server and the client are emphasized. The system is designed with C++ language, and the TCP/IP protocol is used in the server to interact with the client. Software design uses modularity and multi-threaded to improve processing efficiency and ensure functional scalability. At present, the software has been successfully applied to the simultaneous playback of multiple types of missions and multiple channels of video. The actual application results show that the system is stable and can effectively improve the efficiency of model flight tests.

비행체 설계 형상 타당성 확인을 위한 무선조종 모형시험 기법 적용

비행체 설계 접근 방법으로서 무선조종 모형시험 기법 적용 방안을 제시하였다. 본 연구에서 제시된 접근 방법은 동적 상사성을 유지한 축소모형 비행체의 비행특성 분석을 통하여 기본 설계 형상의 타당성을 확인하고 그 결과를 비행체 초기 설계 단계에서 공력 설계 절차에 반영하는 것이다. 축소 비행모형 설계 시 실제적 적용이 가능한 상사 법칙을 개발하기 위하여 비행체 운동을 조종안정성 상사를 위한 회전운동과 비행성능 상사를 위한 병진운동으로 분리하였다. 또한, 무선조종 모형 비행시험을 위한 세부 기법을 개발하였다. 무선조종 비행시험으로부터 얻은 결과를 기초로, 제시된 비행체 설계 접근 방법은 비행체 설계 초기 단계에서 설계 형상 타당성을 확인하는데 유용한 것으로 확인되었다. an approach to air-vehicle design, an application of the radio-controlled model flight test techniques has been presented. The approach presented in this study is to validate the air-vehicle design configuration by analyzing the flight test results of scale model with dynamic similarities, and then to apply the analyzed results to the aerodynamic design process in early stage of the air-vehicle development. To develop practically applicable similarity laws for the subscale flying model design, the air-vehicle motions are decoupled into rotational motions for stability & control similarities and translational motions for flight performance similarities. Also, detail techniques for radio-controlled model flight test have been developed. Based on the results obtained from the radio-controlled flight test, the present approach for air-vehicle design has shown to be useful to validate the air-vehicle design configuration.

Operational and research aspects of a radio-controlled model flight test program

The operational and research aspects of a subscale, radio-controlled model flight-test program are presented. By using low-cost free-flying models, an approach was developed for obtaining research-quality vehicle performance and aerodynamic information. The advantages and limitations learned by applying this approach to a specific flight-test program are described. The research quality of the data acquired shows that model flight testing is practical for obtaining consistent and repeatable flight data.

Comment on 'Model flight tests and neutral point determination'

Comment on 'Model flight tests and neutral point determination'

Propagation of propeller tone noise through a fuselage boundary layer

In earlier experimental and analytical studies, it was found that the boundary layer on an aircraft could provide significant shielding from propeller noise at typical transport airplane cruise Mach numbers. In this paper a new three-dimensional theory is described that treats the combined effects of refraction and scattering by the fuselage and boundary layer. The complete wave field is solved by matching analytical expressions for the incident and scattered waves in the outer flow to a numerical solution in the boundary layer flow. The model for the incident waves is a near-field frequency-domain propeller source theory developed previously for free field studies. Calculations for an advanced turboprop (Prop-Fan) model flight test at 0.8 Mach number show a much smaller than expected pressure amplification at the noise directivity peak, strong boundary layer shielding in the forward quadrant, and shadowing around the fuselage. Results are presented showing the difference between fuselage surface and free-space noise predictions as a function of frequency and Mach number. Comparison of calculated and measured effects obtained in a Prop-Fan model flight test show good agreement, particularly near and aft of the plane of rotation at high cruise Mach number.

Report on Model Flight Tests - Technical Data on the Pawling Shots

Report on Model Flight Tests - Technical Data on the Pawling Shots