Small-Perturbation Analysis of Airplane Dynamics with Dynamic Stability Derivatives Redefined

2005 ◽  
Author(s):  
Brijesh Raghavan ◽  
N Ananthkrishnan
Keyword(s):  
Dynamic Stability ◽  
Small Perturbation ◽  
Perturbation Analysis ◽  
Stability Derivatives

Stability Criterion for Spiral Grooved Thrust Gas Bearings

1990 ◽  
Vol 112 (4) ◽  
pp. 734-737 ◽  
Author(s):  
V. N. Constantinescu ◽  
S. Galetuse
Keyword(s):  
Pressure Distribution ◽  
Dynamic Stability ◽  
Small Perturbation ◽  
Perturbation Analysis ◽  
Stability Criterion ◽  
Analytical Procedure ◽  
Previous Analysis ◽  
Unconditionally Stable ◽  
Thrust Bearings ◽  
Gas Bearing

A previous analysis of dynamic stability for a blocked center inward pumping spiral grooved thrust gas bearing is extended to two other types of similar bearings, namely annular thrust bearings with either inward or outward pumping. Both a numerical small perturbation analysis and an analytical procedure are used, the latter one being based on an approximate shape of the pressure distribution. The analysis provides a critical compressibility number up to which the bearings is unconditionally stable.

scholarly journals A numerical study into the longitudinal dynamic stability of the tailless aircraft

2019 ◽  
Vol 91 (3) ◽  
pp. 428-436 ◽  
Author(s):  
Agnieszka Kwiek
Keyword(s):  
Stability Analysis ◽  
Dynamic Stability ◽  
Numerical Study ◽  
Aircraft Design ◽  
Content Type ◽  
Preliminary Stage ◽  
Longitudinal Dynamic ◽  
Stability Derivatives ◽  
The Impact ◽  
Tailless Aircraft

Purpose The purpose of this research is a study into a mathematical approach of a tailless aircraft dynamic stability analysis. This research is focused on investigation of influence of elevons (elevator) on stability derivatives and consequently on the aircraft longitudinal dynamic stability. The main research question is to determine whether this impact should be taken into account on the conceptual and preliminary stage of the analysis of the longitudinal dynamic stability. Design/methodology/approach Aerodynamic coefficients and longitudinal stability derivatives were computed by Panukl (panel methods). The analysis of the dynamic stability of the tailless aircraft was made by the Matlab code and SDSA package. Findings The main result of the research is a comparison of the dynamic stability of the tailless aircraft for different approaches, with and without the impact of elevator deflection on the trim drag and stability derivatives. Research limitations/implications This paper presents research that mostly should be considered on the preliminary stage of aircraft design and dynamic stability analysis. The impact of elevons deflection on the aircraft moment of inertia has been omitted. Practical implications The results of this research will be useful for the further design of small tailless unmanned aerial vehicles (UAVs). Originality/value This research reveals that in case of the analysis of small tailless UAVs, the impact of elevons deflection on stability derivatives is bigger than the impact of a Mach number. This impact should be taken into consideration, especially for a phugoid mode.

Dynamic stability of closed plasma configurations

1970 ◽  
Vol 4 (4) ◽  
pp. 645-665 ◽  
Author(s):  
Daniel R. Wells
Keyword(s):  
Global Stability ◽  
Dynamic Stability ◽  
Perturbation Analysis ◽  
Flow Fields ◽  
Experimental Results ◽  
Plasma Confinement ◽  
Gauge Symmetries ◽  
Mhd Stability ◽  
The Stability ◽  
Dynamical Principle

The global stability of closed plasma configurations is related to the dynamical principle of least constraint and the spacetime and gauge symmetries of the flow fields. This leads to an entirely new concept of MHD stability which is more basic than stability predictions which rely on a linearized perturbation analysis. The predictions of the theory are compared to recent experimental results obtained in studies of the stability of plasma confinement geometries. The theory predicts the violent ‘instabilities’ of these systems which are currently attributed to other mechanisms. Several pertinent details of the theory which are widely misinterpreted are discussed and clarified.

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