Linearization of Aircraft Landing Equations of Motion with Airframe Flexibility Effects

2021 ◽  
Vol 15 (1) ◽  
Author(s):  
Terrin Stachiw ◽  
Fidel Khouli ◽  
Robert G. Langlois ◽  
Fred F. Afagh
Keyword(s):  
Equations Of Motion ◽  
Aircraft Landing

Calculation of Dynamic Tire Forces from Aircraft Instrumentation Data

2010 ◽  
Vol 38 (3) ◽  
pp. 182-193 ◽  
Author(s):  
Gary E. McKay
Keyword(s):  
System Performance ◽  
Equations Of Motion ◽  
Test Laboratory ◽  
Excellent Correlation ◽  
Friction Behavior ◽  
Aircraft Landing ◽  
Data Scatter ◽  
Tire Forces ◽  
Six Degree Of Freedom ◽  
Tire Friction

Abstract When evaluating aircraft brake control system performance, it is difficult to overstate the importance of understanding dynamic tire forces—especially those related to tire friction behavior. As important as they are, however, these dynamic tire forces cannot be easily or reliably measured. To fill this need, an analytical approach has been developed to determine instantaneous tire forces during aircraft landing, braking and taxi operations. The approach involves using aircraft instrumentation data to determine forces (other than tire forces), moments, and accelerations acting on the aircraft. Inserting these values into the aircraft’s six degree-of-freedom equations-of-motion allows solution for the tire forces. While there are significant challenges associated with this approach, results to date have exceeded expectations in terms of fidelity, consistency, and data scatter. The results show excellent correlation to tests conducted in a tire test laboratory. And, while the results generally follow accepted tire friction theories, there are noteworthy differences.

Effects of magnetic core parameters on landing stability and efficiency of magnetorheological damper-based landing gear system

2019 ◽  
Vol 31 (2) ◽  
pp. 198-208 ◽  
Author(s):  
Chulhee Han ◽  
Bo-Gyu Kim ◽  
Byung-Hyuk Kang ◽  
Seung-Bok Choi
Keyword(s):  
Equations Of Motion ◽  
Magnetic Core ◽  
Landing Gear ◽  
Gear System ◽  
Magnetorheological Damper ◽  
Design Parameters ◽  
Damping Force ◽  
Magnetic Circuits ◽  
Aircraft Landing ◽  
New Type

In this research, a new type of magnetorheological damper for a small-sized aircraft landing gear system is proposed and its performance is evaluated with respect to design parameters of the magnetic core. As a first step, a new configuration of magnetorheological damper for the landing gear system, which consists of orifices, recoil valve, and magnetic circuits, is introduced with working principles. After formulating the governing equations of motion, six different models of magnetorheological damper featuring different number of magnetic core and different pole length are chosen to investigate both the landing stability and the efficiency. Subsequently, the distribution of the magnetic field intensity of each model is analyzed through the finite element method, followed by the calculation of the field-dependent damping force to be used for the landing simulation, which is undertaken by adopting the dynamic model of a half airplane landing gear system. In order to identify the significance of the magnetic core parameters, the landing stability is judged from the sign of the minimum force and the landing efficiency is determined from the energy dissipation during the vertical drop motion.

The motion of a lunar orbiter

1966 ◽  
Vol 25 ◽  
pp. 373
Author(s):  
Y. Kozai
Keyword(s):  
Degrees Of Freedom ◽  
Dimensional Space ◽  
Artificial Satellite ◽  
Equations Of Motion ◽  
Triaxial Ellipsoid ◽  
The Moon ◽  
Secular Motion ◽  
The Earth ◽  
Close Satellite ◽  
The Mean

The motion of an artificial satellite around the Moon is much more complicated than that around the Earth, since the shape of the Moon is a triaxial ellipsoid and the effect of the Earth on the motion is very important even for a very close satellite.The differential equations of motion of the satellite are written in canonical form of three degrees of freedom with time depending Hamiltonian. By eliminating short-periodic terms depending on the mean longitude of the satellite and by assuming that the Earth is moving on the lunar equator, however, the equations are reduced to those of two degrees of freedom with an energy integral.Since the mean motion of the Earth around the Moon is more rapid than the secular motion of the argument of pericentre of the satellite by a factor of one order, the terms depending on the longitude of the Earth can be eliminated, and the degree of freedom is reduced to one.Then the motion can be discussed by drawing equi-energy curves in two-dimensional space. According to these figures satellites with high inclination have large possibilities of falling down to the lunar surface even if the initial eccentricities are very small.The principal properties of the motion are not changed even if plausible values ofJ3andJ4of the Moon are included.This paper has been published in Publ. astr. Soc.Japan15, 301, 1963.

On the motion of comet P/d’Arrest

1974 ◽  
Vol 22 ◽  
pp. 145-148
Author(s):  
W. J. Klepczynski
Keyword(s):  
Equations Of Motion ◽  
Variational Equations ◽  
Partial Derivatives

AbstractThe differences between numerically approximated partial derivatives and partial derivatives obtained by integrating the variational equations are computed for Comet P/d’Arrest. The effect of errors in the IAU adopted system of masses, normally used in the integration of the equations of motion of comets of this type, is investigated. It is concluded that the resulting effects are negligible when compared with the observed discrepancies in the motion of this comet.

Validation of a Belt Model for Prediction of Hub Forces from a Rolling Tire4

2009 ◽  
Vol 37 (2) ◽  
pp. 62-102 ◽  
Author(s):  
C. Lecomte ◽  
W. R. Graham ◽  
D. J. O’Boy
Keyword(s):  
Internal Pressure ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Prediction Method ◽  
Analytical Models ◽  
Beam Model ◽  
Impedance Boundary ◽  
Bending Waves ◽  
Tire Rotation ◽  
Three Dimensional Models

Abstract An integrated model is under development which will be able to predict the interior noise due to the vibrations of a rolling tire structurally transmitted to the hub of a vehicle. Here, the tire belt model used as part of this prediction method is first briefly presented and discussed, and it is then compared to other models available in the literature. This component will be linked to the tread blocks through normal and tangential forces and to the sidewalls through impedance boundary conditions. The tire belt is modeled as an orthotropic cylindrical ring of negligible thickness with rotational effects, internal pressure, and prestresses included. The associated equations of motion are derived by a variational approach and are investigated for both unforced and forced motions. The model supports extensional and bending waves, which are believed to be the important features to correctly predict the hub forces in the midfrequency (50–500 Hz) range of interest. The predicted waves and forced responses of a benchmark structure are compared to the predictions of several alternative analytical models: two three dimensional models that can support multiple isotropic layers, one of these models include curvature and the other one is flat; a one-dimensional beam model which does not consider axial variations; and several shell models. Finally, the effects of internal pressure, prestress, curvature, and tire rotation on free waves are discussed.

COMPARATIVE CHARACTERISTICS OF PHYSICAL AND MECHANICAL PROPERTIES OF COMPOSITE MATERIALS AND HIGH-STRENGTH STEEL 30FGSN2A

2020 ◽  
Author(s):  
I.R. Antypes ◽  
◽  
V.V. Zaitsev ◽  
Keyword(s):  
Composite Materials ◽  
High Strength Steel ◽  
Critical Stress ◽  
Physical And Mechanical Properties ◽  
High Strength ◽  
Aviation Industry ◽  
Specific Strength ◽  
Aircraft Landing ◽  
Carbon Plastics ◽  
Aircraft Landing Gear

Currently, the use of composite materials is increasingly used in various areas of the national economy, including the aviation industry. The materials of this article are devoted to the study of the use of composite materials for the manufacture of aircraft landing gear in comparison with the traditionally used brand of steel. As a result of the work carried out, it was found that the slope made of carbon fiber showed a critical stress twice as high as its design made of 30xgsn2a steel. In addition, carbon plastics are superior to high-strength steel in terms of specific strength, stiffness, and tensile strength.

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