Lateral Stability Derivatives Research Articles

On the Extrapolation of Stability Derivatives to Combined Changes in Airspeed and Angles of Attack and Sideslip

The variation in stability derivatives with airspeed and angles of attack and sideslip is determined using only the dependence of the aerodynamic forces and moments on the modulus and direction of the velocity. Analytic extrapolation factors are obtained for all 12 longitudinal plus 12 lateral stability derivatives of linear decoupled motion. The extrapolation factors relate the stability derivatives for two flight conditions with different airspeeds, angles of attack (AoA), and angles of sideslip (AoS). The extrapolation formulas were validated by comparison with results of computational fluid dynamics (CFD) using Reynolds-averaged Navier–Stokes (RANS) equations. The comparison concerns the extrapolated full longitudinal–lateral stability matrix from one landing and one takeoff condition of a V-tailed aircraft, to 10 other landing and takeoff flight cases with different airspeeds, AoAs, and AoSs. Thus, 420 comparisons were made between extrapolated stability derivatives and CFD–RANS results demonstrating the achievable levels of accuracy.

Investigation of a Light Boxplane Model Using Tuft Flow Visualization and CFD

In this paper, we addressed the flow patterns over a light boxplane scale model to explain the previously discovered disagreement between its predicted and experimental aerodynamic characteristics. By tuft flow and CFD visualization, we explored the causes yielding a large zero lift pitching moment coefficient, lateral divergence, difference in fore and aft elevator lift, and poor high lift performance of the aircraft. The investigation revealed that the discrepancy in the pitching moment coefficient and lateral stability derivatives can be attributed to insufficient accuracy of the used predictive methods. The difference in fore and aft elevator lift and poor high lift performance of the aircraft may occur due to the low local Reynolds number, which causes the early flow separation over the elevators and flaperons when deflected downward at angles exceeding 10°. Additionally, some airframe changes are suggested to alleviate the lateral divergence of the model.

Numerical estimation of aircrafts' unsteady lateral-directional stability derivatives

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.

Design of an Aerolevitation Electric Vehiclefor High-Speed Ground Transportation System

An aerolevitation electric vehicle, acting as a tracked wing-in-ground-effect vehicle, is conceptually designed to match the design requirements. The aerodynamic interaction between the vehicle and its track is investigated using a combination of approaches. A boundary-element method is used to study the effect of steady, nonplanar ground effect on the vehicle. The more complicated flow characteristics are investigated using a Navier-Stokes computation. The data obtained from the numerical simulations are compared with the data measured from wind-tunnel tests. The results computed using the boundary-element method agree with the measured data. The longitudinal and lateral stability derivatives are estimated, and a guidance and control system is designed using intelligent techniques based on the estimated stability derivates.

On the Linear Hydrodynamic Forces and the Maneuverability of an Unmanned Untethered Submersible with Streamlined Body (2nd Report : Lateral Motions)

A series of captive model tests was carried out to unmanned untethered submersible AUV-HMl testbed, which has a body of a streamlined section, developed at National Taiwan University. Furthermore, for estimating its lateral stability derivatives the same method, which is based on the empirical formula proposed by Bottaccini and used in previous paper, is applied. As a result, both of the two sets of stability indices evaluated with estimated values of stability derivatives as well as those obtained by measurement, show that AUV-HMl testbed is unstable on lateral mode. This result agrees well with the tendency shown by the vehicle responses for step heading commands in the pool test performed with the AUV-HMl testbed.

An Improved Solution of the Two-Dimensional Jet-Flapped Airfoil Problem

3 Partridge, D. W. and Pecover, B. E., An Application of the RAE Wind-Tunnel/Flight Dynamics Simulator to the Speed Dynamics of a Slender Delta Aircraft (HP 115), Repts. and Memos. 3669, 1969, Aeronautical Research Council, London, England. 4 Engler, P. B. E. and Moss, G. F., Low-Speed Tunnel Tests on a ith Scale Model of the Handley Page HP 115, Repts. and Memos. 3486, 1965, Aeronautical Research Council, London, England. 5 Thompson, J. S. and Fail, R. A., Derivative Measurement on Sting-Mounted Wind-Tunnel Models at RAE Bedford, AGARD Current Paper 17, 1966. 6 Beecham, L. J. and Titchener, I. M., Some Notes on an Approximate Solution for the Free Oscillation Characteristics of Nonlinear Systems Typified by x + F(x,x) = 0, Repts. and Memos. 3651, 1969, Aeronautical Research Council, London, England. 7 KrylofT, N. and Bogoliuboff, N., Introduction to Nonlinear Mechanics, Princeton University Press, Princeton, N.J., 1937. 8 Ross, A. J. and Beecham, L. J., An Approximate Analysis of the Nonlinear Lateral Motion of a Slender Aircraft (HP 115) at Speeds, Repts. and Memos. 3674, 1971, Aeronautical Research Council, London, England. 9 Henderson, J. M., Low Speed Handling of a Slender Delta (HP 115), Journal of the Royal Aeronautical Society, Vol. 69, No. 653, 1965, pp. 311-324. 10 Thompson, J. S., Fail, R. A., and Inglesby, J. V., Low Speed Wind-Tunnel Measurements of the Oscillatory Lateral Stability Derivatives for a Model of the Slender Aircraft (HP 115) Including the Effects of Frequency Parameter, Current Paper 1097, 1969, Aeronautical Research Council, London, England.

The Lateral Stability Derivatives and Equations.

The Lateral Stability Derivatives and Equations.