Aeroelastic analysis of remotely controlled research vehicles with numerous control surfaces

Goraj, Zdobysław; Chajec, Wojciech

doi:10.1108/17579861111135914

Cited by 4 publications

(6 citation statements)

References 2 publications

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“…Four data-files are used for numerical analysis, containing respectively: FEM, panel-solid model for non-stationary aerodynamics, a set of parameters necessary to run analysis, and a set of nodes to interpolate movement of aerodynamic elements. A detailed description of the methodology, calculated examples, and obtained results have been published in works: [11][12][13][14]. In the numerical process, the flutter equation is transformed into a complex eigenvalue problem with p as the complex variable.…”

Section: Methods Of Analysis With Program Techniques Available In Msc...mentioning

confidence: 99%

Techniques for adjusting qualities of aircraft structural models for more effective aeroelastic flutter analyses

Olejnik

Kachel

Rogólski

2023

J. Phys.: Conf. Ser.

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To solve numerically the problem of aeroelastic flutter, two virtual components are required: a structural finite element model (FEM) and an aerodynamic model. MSC Software package containing Nastran with embedded flutter solution enables to perform calculations with the use of an integrated aeroelastic model. For data block including the model and the set of entry parameters, flutter equation is being solved. On the basis of postprocessed output data curves of run for resulting parameters can be plotted which gives information of flutter critical point. Numerical results may be subject to some uncertainty. Result deviation could occur as effects of various factors resulting from inaccurate geometry or poor structural qualities of mapped aircraft. Structural defects affecting mass or stiffness matrices of FEM are often hard to identify. Aspects important for effective flutter solutions are strictly connected with the coincidence of structural properties of the real aircraft and its model. In the paper, the method of numerical flutter analysis was presented with the use of techniques available in MSC Nastran. Three assessment methods were proposed to identify structural parameters usable for validating FEMs. The method of mass correction relies on adjustment of model mass values and tuning the location of the center of mass of the model to the coordinates of the location of the center of mass of the real aircraft. For adjusting stiffness of model parts, very useful are results obtained from strength test of the real airframe. The completely reliable but costly method is performing ground vibration tests (GVT) to measure precisely resonant frequencies and natural modes of free vibrations. The results obtained from experiments should be treated as the referenced, but tuning FEM to them requires both adjusting numerical eigenfrequencies and normal modes.

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Section: Methods Of Analysis With Program Techniques Available In Msc...mentioning

confidence: 99%

Techniques for adjusting qualities of aircraft structural models for more effective aeroelastic flutter analyses

Olejnik

Kachel

Rogólski

2023

J. Phys.: Conf. Ser.

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“…There are many publications from the area of aircraft vibration testing, like the ones recognized by authors and worth of being referenced in this elaborate. 2,6–15 Unfortunately, most of them are focused on testing objects and obtained results, but not necessarily on the core of experiment which in fact is a technological process including specific working techniques. Some of them are at least briefly described in current point.…”

Section: Measuring Equipment and Applied Methodologymentioning

confidence: 99%

“…Several methods for measuring generalized coefficients are known and have been described, inter alia, in literature. 2,5,6 The component has a characteristic run in the close-to-resonance band (Figure 3) with two extreme values. Run of amplitude curve shows the relationship resulting from the solution of equation (7), which is…”

Section: Introductionmentioning

confidence: 99%

Application of ground vibration testing in small manned or unmanned aircraft prototyping

Olejnik

Kachel

Rogólski

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part G:

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The article describes the vibration measurement technology used in experimental investigation of light aircraft and some series of exemplary results obtained during the prototyping process. The aim of investigations presented herein was to determine the resonant frequencies and natural modes of an aircraft or its selected structural components. Ground vibration testing is an essential dynamic structural test necessary to carry out before the aircraft certification. This test should be performed on the aircraft example which is predicted to be tested in flight. The measuring system used for ground vibration testing in the Institute of Aviation Technology of the Military University of Technology consists of a multi-channel LMS SCADAS analyzer, a set of piezoelectric accelerometers, two vibration exciters equipped with impedance heads and a computer with the Test.Lab Software. The aim of the article was to present the methodology of performing ground vibration testing tests. Having applied the equipment to measure an airplane or its airframe component, key vibration characteristics corresponding to specific resonant points can be determined. Not only completed aircraft can be tested but also its isolated fragments (wings, stabilizers, tail units) or just empty airframe. Testing separately supported components allows examining their aeroelastic properties at early stage of prototyping. Ground vibration testing technology applied in various stages of the prototyping process was demonstrated in four peculiar research cases. The testing examples presented herein were the following: the isolated strut-braced wing of a light reconnaissance airplane, the light drone imitating an aerial target for some on-ground anti-aircraft artillery sets, the empty airframe of a very light jet and the miniature UAV. Some exemplary results obtained from testing these objects were presented. At the end, some observations and conclusions were noted in the context of usefulness of conducted researches.

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“…The control system modes are important in the mode set for flutter analysis. The most simply case is if the control surface is powered by actuator (Goraj and Chajec, 2011). However, aircraft usually are operated manually by means of mechanical control system or even automatically (aero-servo-elasticity [ASE]).…”

Section: Generalized Masses Determinationmentioning

confidence: 99%

“…The software was used for many years for flutter analyses based on both computed or measured normal modes of light aircraft in low subsonic range of speed, e.g. (Chajec, 1993), (Goraj and Chajec, 2011, the Samonit vehicle only) and Chajec (2010). The present version of the software is re-compiled and improved.…”

Section: Work Descriptionmentioning

confidence: 99%

Comparison of flutter calculation methods based on ground vibration test result

Chajec

2019

AEAT

Self Cite

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PurposeA low-cost but credible method of low-subsonic flutter analysis based on ground vibration test (GVT) results is presented. The purpose of this paper is a comparison of two methods of immediate flutter problem solution: JG2 – low cost software based on the strip theory in aerodynamics (STA) and V-g method of the flutter problem solution and ZAERO I commercial software with doublet lattice method (DLM) aerodynamic model and G method of the flutter problem solution. In both cases, the same sets of measured normal modes are used. Design/methodology/approachBefore flutter computation, resonant modes are supplied by some non-measurable but existing modes and processed using the author’s own procedure. For flutter computation, the modes are normalized using the aircraft mass model. The measured mode orthogonalization is possible. The flutter calculation made by means of both methods are performed for the MP-02 Czajka UL aircraft and the Virus SW 121 aircraft of LSA category. FindingsIn most cases, both compared flutter computation results are similar, especially in the case of high aspect wing flutter. The Czajka T-tail flutter analysis using JG2 software is more conservative than the one made by ZAERO, especially in the case of rudder flutter. The differences can be reduced if the proposed rudder effectiveness coefficients are introduced. Practical implicationsThe low-cost methods are attractive for flutter analysis of UL and light aircraft. The paper presents the scope of the low-cost JG2 method and its limitations. Originality/valueIn comparison with other works, the measured generalized masses are not used. Additionally, the rudder effectiveness reduction was implemented into the STA. However, Niedbal (1997) introduced corrections of control surface hinge moments, but the present work contains results in comparison with the outcome obtained by means of the more credible software.

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Aeroelastic analysis of remotely controlled research vehicles with numerous control surfaces

Cited by 4 publications

References 2 publications

Techniques for adjusting qualities of aircraft structural models for more effective aeroelastic flutter analyses

Techniques for adjusting qualities of aircraft structural models for more effective aeroelastic flutter analyses

Application of ground vibration testing in small manned or unmanned aircraft prototyping

Comparison of flutter calculation methods based on ground vibration test result

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