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Results for “STATIC STABILITY”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

An analytical study of turbulence responses, including horizontal-tail loads, of a control-configured vehicle with relaxed static stability

A static stability augmentation system (SSAS) with angle-of-attack, pitch-rate, and forward-speed feedback is used to stabilize control-configured rigid vehicles with relaxed static stability. Airplane configurations include a baseline configuration and two representative control-configured vehicle configurations. The first statically unstable configuration has baseline geometry and an aft center of gravity; the second statically unstable configuration has reduced tail length and area and a forward neutral point. Stability, flying-qualities, and maneuverability requirements are imposed on the airplane-SSAS systems. Turbulence responses of the rigid airframe and tail loads are examined in terms of configuration changes for a given control law and in terms of control law changes for a given configuration.

Perry, B., III↗
NASA NTRS1933

The effect of a gap between elevator and stabilizer on the static stability and maneuverability about the lateral axis in flight

A number of German airplanes have a gap between elevator and stabilizer. The effect of this open space is not generally known, although English wind-tunnel experiments have shown that even a very small gap exerts a profound influence on the elevator action. The purpose of the present free-flight measurements is to ascertain whether fairing over the gap would actually result in an appreciable improvement.

Hubner, Walter↗
NASA NTRS2012

MATLAB Stability and Control Toolbox Trim and Static Stability Module

MATLAB Stability and Control Toolbox (MASCOT) utilizes geometric, aerodynamic, and inertial inputs to calculate air vehicle stability in a variety of critical flight conditions. The code is based on fundamental, non-linear equations of motion and is able to translate results into a qualitative, graphical scale useful to the non-expert. MASCOT was created to provide the conceptual aircraft designer accurate predictions of air vehicle stability and control characteristics. The code takes as input mass property data in the form of an inertia tensor, aerodynamic loading data, and propulsion (i.e. thrust) loading data. Using fundamental nonlinear equations of motion, MASCOT then calculates vehicle trim and static stability data for the desired flight condition(s). Available flight conditions include six horizontal and six landing rotation conditions with varying options for engine out, crosswind, and sideslip, plus three take-off rotation conditions. Results are displayed through a unique graphical interface developed to provide the non-stability and control expert conceptual design engineer a qualitative scale indicating whether the vehicle has acceptable, marginal, or unacceptable static stability characteristics. If desired, the user can also examine the detailed, quantitative results.

Kenny, Sean P.↗
NASA NTRS2006

Matlab Stability and Control Toolbox: Trim and Static Stability Module

This paper presents the technical background of the Trim and Static module of the Matlab Stability and Control Toolbox. This module performs a low-fidelity stability and control assessment of an aircraft model for a set of flight critical conditions. This is attained by determining if the control authority available for trim is sufficient and if the static stability characteristics are adequate. These conditions can be selected from a prescribed set or can be specified to meet particular requirements. The prescribed set of conditions includes horizontal flight, take-off rotation, landing flare, steady roll, steady turn and pull-up/ push-over flight, for which several operating conditions can be specified. A mathematical model was developed allowing for six-dimensional trim, adjustable inertial properties, asymmetric vehicle layouts, arbitrary number of engines, multi-axial thrust vectoring, engine(s)-out conditions, crosswind and gyroscopic effects.

Crespo, Luis G.↗
NASA NTRS1949

Preliminary Results of a Free-Flight Investigation of the Static Stability and Aileron Control Characteristics of 1/6 Scale Models of the Bell MX-776

An investigation of the static longitudinal stability, static directional stability, and aileron control characteristics at transonic and supersonic speeds is being made of 1/6 scale rocket-propelled model of the Bell MX-776. A stability investigation has been made of two symmetrical models with controls undeflected and centers of gravity one-half and one-body diameter, respectively, ahead of the equivalent design center-of-gravity location of the full-scale version. Both models developed large normal-force coefficients in both the subsonic and supersonic ranges which indicated longitudinal instability at low angles of attack. The side-force coefficients were small for both models and indicated that the models were directionally stable. A possible tendency toward dynamic directional instability in the transonic region was indicated by short-period oscillations of the side forces. The results showed a partial-span inboard aileron to be ineffective or to cause negative control in the the transonic region when deflected approximately 5 deg but not when deflected 10 deg. An investigation of drag showed it to increase with a rearward movement of the center of gravity. This indicates an increase in the trim angle of attack as could be caused by a decrease in static stability.

Michal, David H.↗
NASA NTRS1988

Static stability variations during a winter marine cyclone development

The relationship between lower tropospheric static stability and a case of explosive marine cyclone development is examined. The case studied is a cyclone which developed between January 18-21, 1979, about 500 km south of Nova Scotia. Diagnoses of the static stability parameter for this case are presented. Also, the static stability parameters and sea level pressures during marine cyclone development and continental development are compared.

Tsou, Chih-Hua↗
NASA NTRS1993

The role of large-scale eddies in the climate equilibrium. Part 2: Variable static stability

Lorenz's two-level model on a sphere is used to investigate how the results of Part 1 are modified when the interaction of the vertical eddy heat flux and static stability is included. In general, the climate state does not depend very much on whether or not this interaction is included, because the poleward eddy heat transport dominates the eddy forcing of mean temperature and wind fields. However, the climatic sensitivity is significantly affected. Compared to two-level model results with fixed static stability, the poleward eddy heat flux is less sensitive to the meridional temperature gradient and the gradient is more sensitive to the forcing. For example, the logarithmic derivative of the eddy flux with respect to the gradient has a slope that is reduced from approximately 15 on a beta-plane with fixed static stability and approximately 6 on a sphere with fixed static stability, to approximately 3 to 4 in the present model. This last result is more in line with analyses from observations. The present model also has a stronger baroclinic adjustment than that in Part 1, more like that in two-level beta-plane models with fixed static stability, that is, the midlatitude isentropic slope is very insensitive to the forcing, the diabatic heating, and the friction, unless the forcing is very weak.

Zhou, Shuntai↗
NASA NTRS1980

A piloted simulator investigation of static stability and stability/control augmentation effects on helicopter handling qualities for instrument approach

A ground simulator experiment was conducted on the Flight Simulator for Advanced Aircraft at Ames Research Center to investigate the influence of several static stability and stability/control augmentation design parameters on helicopter flying qualities during terminal area operations in instrument conditions. Effects of light turbulence were included. Two levels of static stability in each rotational axis (pitch, roll, yaw) were examined for a hingeless rotor configuration. The variations in pitch and roll were: (1) stable and (2) neutral static stability; in yaw there were two stable levels. Four types of stability/control augmentation were also examined for the lower level of static stability in each axis. This latter investigation covered three helicopter rotor types: hingeless, articulated, and teetering. Four pilots performed a total of 105 evaluations of these parameters for a representative VOR instrument approach task. Pilot rating results indicate the acceptability of neutral static stability longitudinally and laterally and the need for pitch-roll attitude augmentation to achieve a satisfactory system.

Lebacqz, J. V.↗
NASA NTRS2015

Study of Geometric Porosity on Static Stability and Drag Using Computational Fluid Dynamics for Rigid Parachute Shapes

This paper explores use of computational fluid dynamics to study the e↵ect of geometric porosity on static stability and drag for NASA's Multi-Purpose Crew Vehicle main parachute. Both of these aerodynamic characteristics are of interest to in parachute design, and computational methods promise designers the ability to perform detailed parametric studies and other design iterations with a level of control previously unobtainable using ground or flight testing. The approach presented here uses a canopy structural analysis code to define the inflated parachute shapes on which structured computational grids are generated. These grids are used by the computational fluid dynamics code OVERFLOW and are modeled as rigid, impermeable bodies for this analysis. Comparisons to Apollo drop test data is shown as preliminary validation of the technique. Results include several parametric sweeps through design variables in order to better understand the trade between static stability and drag. Finally, designs that maximize static stability with a minimal loss in drag are suggested for further study in subscale ground and flight testing.

Greathouse, James S.↗
NASA NTRS1988

Static stability variations during the development of an intense extratropical cyclone

The role of static stability (sigma) is diagnosed for an intense extratropical cyclone that developed over the central United States during January 9-11, 1975. Results indicate that minimum sigma values occurred in the lower troposphere at 0000 UTC January 10, 1975, during the period of slow cyclone development, and then increased as rapid development proceeded. Further, the upward advection of smaller static stabilities in the cyclone area, a forcing process in the height tendency equation, resulted in a significant reduction of height falls attributed to vorticity advection, thermal advection, and latent heat release.

Smith, Phillip J.↗
NASA NTRS1948

An Investigation of the Low-speed Static Stability Characteristics of Complete Models Having Sweptback and Sweptforward Wings

An investigation has been conducted in the Langley 300 MPH 7- by 10-foot tunnel to determine the static stability characteristics at low speeds of complete models with various swept wings so that comparisons might be made with available theoretical and empirical methods of predicting the stability characteristics. Longitudinal and lateral stability characteristics, flaps up and down, were obtained for models having 0 degree, 15 degrees, 30 degrees, and 45 degrees sweptforward and sweptback wings.

SWEEP - COMPLETE WINGS↗
NASA NTRS1976

Lateral ride quality of the B-1 aircraft subjected to a reduction of lateral static stability

A method to evaluate the lateral ride quality of a B-1 aircraft subjected to a reduction in lateral static stability is developed. Ride quality is then found for three different relaxed static stability configurations which are augmented by yaw rate feedback to restore specified handling qualities. These cases are compared to the ride quality of the unrelaxed aircraft with the same handling qualities.

Hinsdale, A. J.↗