scholarly journals Numerical estimation of aircrafts' unsteady lateral-directional stability derivatives

2006 ◽  
Vol 33 (4) ◽  
pp. 311-337
Author(s):  
N.L. Maricic
Keyword(s):  
Cross Sections ◽  
Vertical Plane ◽  
Lattice Method ◽  
Slender Body Theory ◽  
Directional Stability ◽  
Load Distributions ◽  
Stability Derivatives ◽  
Lifting Surfaces ◽  
Body Theory ◽  
Control Surfaces

A technique for predicting steady and oscillatory aerodynamic loads on general configuration has been developed. The prediction is based on the Doublet-Lattice Method, Slender Body Theory and Method of Images. The chord and span wise loading on lifting surfaces and longitudinal bodies (in horizontal and vertical plane) load distributions are determined. The configuration may be composed of an assemblage of lifting surfaces (with control surfaces) and bodies (with circular cross sections and a longitudinal variation of radius). Loadings predicted by this method are used to calculate (estimate) steady and unsteady (dynamic) lateral-directional stability derivatives. The short outline of the used methods is given in [1], [2], [3], [4] and [5]. Applying the described methodology software DERIV is developed. The obtained results from DERIV are compared to NASTRAN examples HA21B and HA21D from [4]. In the first example (HA21B), the jet transport wing (BAH wing) is steady rolling and lateral stability derivatives are determined. In the second example (HA21D), lateral-directional stability derivatives are calculated for forward- swept-wing (FSW) airplane in antisymmetric quasi-steady maneuvers. Acceptable agreement is achieved comparing the results from [4] and DERIV.

scholarly journals Software development for subsonic aircraft’s unsteady longitudinal stability derivatives calculation

2005 ◽  
Vol 32 (4) ◽  
pp. 319-340 ◽  
Author(s):  
Nikola Maricic
Keyword(s):  
Method Of Images ◽  
Lattice Method ◽  
Aerodynamic Stability ◽  
Slender Body Theory ◽  
Stability Derivatives ◽  
Doublet Lattice Method ◽  
Body Theory ◽  
General Configuration ◽  
Finite Element Methodology ◽  
Good Agreement

Subsonic general configuration aircrafts? unsteady longitudinal aerodynamic stability derivatives can be estimated using finite element methodology based on the Doublet Lattice Method (DLM), the Slender Body Theory (SBT) and the Method of Images (MI). Applying this methodology, software DERIV is developed. The obtained results from DERIV are compared to NASTRAN examples HA21A and HA75H. A good agreement is achieved.

scholarly journals Analysis of Dynamic Stability of Planing Craft on the Vertical Plane

2014 ◽  
Vol 8 (15) ◽  
pp. 35 ◽  
Author(s):  
Roberto Algarín ◽  
Oscar Tascón
Keyword(s):  
Dynamic Model ◽  
Dynamic Stability ◽  
Vertical Plane ◽  
Slender Body ◽  
Critical Conditions ◽  
Wagner Model ◽  
Slender Body Theory ◽  
Planing Craft ◽  
Body Theory

A dynamic model for the motion of planing craft on the vertical plane was developed; the motions ofsurge, heave, and pitch are coupled. Critical conditions that produce the inception of instability are evaluated. The Wagner model (1932) for 2D impact is extended for section with knuckles. Planing hullswere analyzed through the application of slender body theory. The results are compared with Tveitnes(2001), Peterson (1997), Savitsky (1964), Troesch (1992) and Celano (1998).

A Numerical Study on Squat of a Wigley Hull

2011 ◽  
Author(s):  
Mahmoud Alidadi ◽  
Sander Calisal
Keyword(s):  
Boundary Element Method ◽  
Cross Section ◽  
Cross Sections ◽  
Numerical Study ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Slender Body Theory ◽  
Flow Potential ◽  
Wigley Hull ◽  
Body Theory

A numerical study is conducted to calculate the squat for a wigley hull. An approach based on slender body theory is used to convert the three dimensional ship problem into a series of two dimensional problems in cross sections from bow to stern (solved sequentially in time). A boundary element method is used to compute the flow potential at every cross section. The ship squat is calculated from the pressure integration over the hull. Numerical results for the Wigley hull is presented and compared with the experimental results.

On the Low Aspect Ratio Oscillating Rectangular Wing in Supersonic Flow

1953 ◽  
Vol 4 (2) ◽  
pp. 231-244 ◽  
Author(s):  
John W. Miles
Keyword(s):  
Supersonic Flow ◽  
Aspect Ratio ◽  
Velocity Potential ◽  
Fourth Power ◽  
Slender Body Theory ◽  
Single Degree ◽  
Low Aspect Ratio ◽  
Stability Derivatives ◽  
The Laplace Transform ◽  
Body Theory

SummaryThe Laplace transform of the lift distribution on an oscillating rectangular wing in a supersonic flow is obtained by separating the linearised equation for the velocity potential in elliptic (cylindrical) co-ordinates. The results for the case of no spanwise distortion are expanded in ascending powers of the aspect ratio in order to compare with the slender body theory, and the longitudinal stability derivatives are calculated. It is found that at either supersonic or transonic speeds single-degree-offreedom instability in pitch is impossible insofar as the fourth power of the aspect ratio is neglected.

Two-Dimensional Apparent Masses for Cross-Flow Sections of Wing-Store Configurations

1982 ◽  
Vol 49 (3) ◽  
pp. 471-475
Author(s):  
M.-K. Huang
Keyword(s):  
Approximate Method ◽  
Cross Flow ◽  
Slender Body ◽  
Two Dimensional ◽  
Aerodynamic Stability ◽  
Slender Body Theory ◽  
Rolling Moment ◽  
Stability Derivatives ◽  
The Cross ◽  
Body Theory

On the basis of the assumption that the external stores are small compared with the wing, an approximate method has been developed for estimation of two-dimensional apparent masses for the cross-flow sections of wing-store combinations. The results obtained may be applicable to the analysis of the effects of the stores on the aerodynamic stability derivatives in slender-body theory. The theory has also been applied to estimate the rolling moment due to sideslip for high-wing configurations. The presented results are in agreement with those of other investigations.

A Prediction of Dynamic Stresses for Long, Large-Diameter Horizontal Pipes at or Near the Ocean Free Surface

1995 ◽  
Vol 117 (4) ◽  
pp. 239-244 ◽  
Author(s):  
G. C. Nihous
Keyword(s):  
Free Surface ◽  
Large Diameter ◽  
Vertical Plane ◽  
Slender Body Theory ◽  
Modal Expansion ◽  
Horizontal Pipes ◽  
Straight Beam ◽  
Bending Stresses ◽  
Wave Angle ◽  
Body Theory

A straight-beam approximation is applied to a long, stiff pipeline located at or near the ocean free surface. The analytical model determines vertical and horizontal transverse motions in a linear frequency-domain framework. Longitudinal dependence is expressed through a modal expansion, with the hydrodynamic loads calculated through slender-body theory. This method is validated by comparing predicted bending stresses for a 9.1-m-(30-ft-) dia pipe with corresponding model basin data. Maximum stresses occur when the wave angle allows a simultaneous matching of frequencies and projected wavelengths. Results also show peak stresses near the aft end of the pipe. Finally, it is confirmed that in deep water, bending stresses in the horizontal plane are in general smaller than those in the vertical plane.

Force and Power Estimation in Fish-Like Locomotion Using a Vortex-Lattice Method

1999 ◽  
Vol 122 (2) ◽  
pp. 239-253 ◽  
Author(s):  
H. Kagemoto ◽  
M. J. Wolfgang ◽  
D. K. P. Yue ◽  
M. S. Triantafyllou
Keyword(s):  
Vortex Lattice ◽  
Practical Interest ◽  
Power Estimation ◽  
Quantitative Agreement ◽  
Slender Body ◽  
Lattice Method ◽  
Slender Body Theory ◽  
Vortex Lattice Method ◽  
Linearized Theory ◽  
Body Theory

The forces and power needed for propelling at constant speed an actively swimming flexible fish-like body are calculated. A vortex-lattice method based on a linearized theory is employed and the results are compared against slender body theory predictions, as well as experimental data from an eight-link robotic instrument, the RoboTuna. Qualitative agreement is found between our method and slender body theory; with quantitative agreement over certain parametric ranges and disagreement for other ranges of practical interest. The present linearized vortex lattice calculations predict the power needed for propelling the RoboTuna with less than 20 percent error in most experiments conducted. [S0098-2202(00)01202-5]

A generalized slender-body theory for fish-like forms

1973 ◽  
Vol 57 (4) ◽  
pp. 673-693 ◽  
Author(s):  
J. N. Newman ◽  
T. Y. Wu
Keyword(s):  
The Body ◽  
Slender Body ◽  
Slender Body Theory ◽  
Vortex Sheets ◽  
Flow Past ◽  
Longitudinal Orientation ◽  
Trailing Edges ◽  
Lifting Surfaces ◽  
Axisymmetric Bodies ◽  
Body Theory

A consistent slender-body approximation is developed for the flow past a fish- like body with arbitrary combinations of body thickness and low-aspect-ratio fin appendages, but with the fins confined to the plane of symmetry of the body. Attention is focused on the interaction of the fin lifting surfaces with the body thickness, and especially on the dynamics of the vortex sheets shed from the fin trailing edges. This vorticity is convected by the (non-lifting) flow past the stretched-straight body, and departs significantly from the purely longitudinal orientation of conventional lifting-surface theory. Explicit results are given for axisymmetric bodies having fins with abrupt trailing edges, and calculations of the total lift force are presented for bodies with symmetric and asymmetric fin configurations, moving with a constant angle of attack.

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