Abstract

In this paper, the dynamic stability analysis of a rolling airframe actuated by one pair ON-OFF actuator using linear theory is presented via developing a new closed form solution. The effect of discontinuous forcing term on rolling airframe stability is studied. In contrast to tricyclic motion with constant forcing term (constant non-homogeneous term) in which only the amplitude of nutation and precession is affected, it is found that ON-OFF control affects both amplitude and phase of nutation and precession motions. In the case of discontinuous control surface, there are two sources for resonance instability. Finally, through simulation results of closed form solutions, a comparison between airframe’ response to ideal and real ON-OFF command is achieved. The effect of ON-OFF control on angular motion is also evaluated.

Highlights

  • During the last few decades, the use of rolling airframes is increased

  • The linear theory is used in studying the dynamic stability of rolling airframe with one pair ON-OFF actuator

  • Utilizing the developed analytical models, the following notable results are obtained: It is shown that the ON-OFF control affects both amplitude and phase of nutation and precession motions

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Summary

Introduction

During the last few decades, the use of rolling airframes is increased. The main benefit of rolling motion is overcoming the effect of airframe asymmetries due to thrust or fins misalignment. The equations of motion of rolling airframe in bodyfixed frame and in non-rolling frame are developed in literature (Nicolaides, 1953; Murphy, 1963, 1981, 1971; Cohen et al, 1974) Relying on these models, the stability analysis of free flight motion and the effect of small asymmetries due to control surfaces deflections or fins misalignment is performed. The effect of one pair ON-OFF control surface on dynamic stability behavior of a rolling airframe is concentrated in the current research. In this regard, a new analytical relation is derived for ideal and real ON-OFF control surface. Based on the linear theory, new closed form solutions are derived for rolling airframe motion in presence of ON-OFF control surface model.

Mq Ix p Iy
Closed form solution derivation
Closed form solution for ideal ON-OFF control surface
Closed form solution for real ON-OFF control surface
Angular motion of ON-OFF controlled airframe
Effect of roll rate on resonance instability
Validation of proposed closed form solutions
Conclusions

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