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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 NTRS1952

Experimental Determination of the Effect of Horizontal-Tail Size, Tail Length, and Vertical Location on Low-Speed Static Longitudinal Stability and Damping Pitch of a Model Having 45 Degree Sweptback Wing and Tail Surfaces

Report presents the results of an investigation conducted in the Langley stability tunnel to determine the effects of horizontal tails of various sizes and at various tail lengths (when loaded on the fuselage center line) and also the effects of vertical location of the horizontal tail relative to the wing on the low-speed static longitudinal stability and on the steady-state rotary damping in pitch for a complete-model configuration. The wing and tail surfaces had the quarter-chord lines swept back 45 degrees and had aspect ratios of 4. The results of the investigation showed that, in agreement with analytical considerations, the contribution of the horizontal tail to static longitudinal stability was related directly to the tail size and length; whereas, its contribution to damping in pitch was related directly to tail size and the square of tail length.

Lichtenstein, Jacob H↗
NASA NTRS1961

Aerodynamic Loads at Mach Numbers from 0.70 to 2.22 on an Airplane Model Having a Wing and Canard of Triangular Plan Form and Either Single or Twin Vertical Tails Supplement I-Tabulated Data for the Model with Single Vertical Tails: Tabulated Data for the Model with Single Vertical Tail - Supplement 1

Tabulated results of a wind-tunnel investigation of the aerodynamic loads on a canard airplane model with a single vertical tail are presented for Mach numbers from 0.70 to 2.22. The Reynolds number for the measurements was 2.9 x 10(exp 6) based on the wing mean aerodynamic chord. The results include local static pressure coefficients measured on the wing, body, and vertical tail for angles of attack from -4 deg to + 16 deg, angles of sideslip of 0 deg and 5.3 deg, vertical-tail settings of 0 deg and 5 deg, and nominal canard deflections of 0 deg and 10 deg. Also included are section force and moment coefficients obtained from integrations of the local pressures and model-component force and moment coefficients obtained from integrations of the section coefficients. Geometric details of the model and the locations of the pressure orifices are shown. An index to the data contained herein is presented and definitions of nomenclature are given.

Peterson, Victor L.↗
NASA NTRS1959

Effect of Horizontal-Tail Chord on the Calculated Subsonic Span Loads and Stability Derivatives of Isolated Unswept Tail Assemblies in Sideslip and Steady Roll

Subsonic span loads and the resulting stability derivatives have been calculated using the discrete-horseshoe-vortex method for a systematic series of horizontal tails in combination with a vertical tail of aspect ratio 1.0 in order to provide information on the effect of varying the chord of the horizontal tail for isolated tail assemblies performing sideslip and steady-roll motions. In addition, the effects of horizontal-tail dihedral angle for the sideslip case were obtained. Each tail surface considered had a taper ratio of 0.5 and an unswept quarter-chord line. The investigation covered variations in horizontal-tail chord, horizontal-tail span, and vertical location of the horizontal tail. The span loads and the resulting total stability derivatives as well as the vertical- and horizontal-tail contributions to these tail-assembly derivatives are presented in the figures for the purpose of showing the influence of the geometric variables. The results of this investigation showed trends that were in agreement with the results of previous investigations for variations in horizontal-tail span and vertical location of the horizontal tail. Variations in horizontal-tail chord expressed herein in terms of the root-chord ratio, that is, the ratio of horizontal-tail root chord to vertical-tail root chord, were found to have a pronounced influence on most of the span loads and the resulting stability derivatives. For most of the cases considered, the rate of change of the span load coefficients and the stability derivatives with the root-chord ratio was found to be a maximum for small values of root-chord ratio and to decrease as root-chord ratio increased.

Booth, Katherine W.↗
NASA NTRS1958

Some Effects of Horizontal-Tail Position on the Vertical-Tail Pressure Distributions of a Complete Model in Sideslip at High Subsonic Speeds

An investigation has been made in the Langley high-speed 7- by 10-foot tunnel of some effects of horizontal-tail position on the vertical-tail pressure distributions of a complete model in sideslip at high subsonic speeds. The wing of the model was swept back 28.82 deg at the quarter-chord line and had an aspect ratio of 3.50, a taper ratio of 0.067, and NACA 65A004 airfoil sections parallel to the model plane of symmetry. Tests were made with the horizontal tail off, on the wing-chord plane extended, and in T-tail arrangements in forward and rearward locations. The test Mach numbers ranged from 0.60 to 0.92, which corresponds to a Reynolds number range from approximately 2.93 x 10(exp 6) to 3.69 x 10(exp 6), based on the wing mean aerodynamic chord. The sideslip angles varied from -3.9 deg to 12.7 deg at several selected angles of attack. The results indicated that, for a given angle of sideslip, increases in angle of attack caused reductions in the vertical-tail loads in the vicinity of the root chord and increases at the midspan and tip locations, with rearward movements in the local chordwise centers of pressure for the midspan locations and forward movements near the tip of the vertical tail. At the higher angles of attack all configurations investigated experienced outboard and rearward shifts in the center of pressure of the total vertical-tail load. Location of the horizontal tail on the wing- chord plane extended produced only small effects on the vertical-tail loads and centers of pressure. Locating the horizontal tail at the tip of the vertical tail in the forward position caused increases in the vertical-tail loads; this configuration, however, experienced considerable reduction in loads with increasing Mach number. Location of the horizontal tail at the tip of the vertical tail in the rearward position produced the largest increases in vertical-tail loads per degree sideslip angle; this configuration experienced the smallest variations of loads with Mach number of any of the configurations investigated.

Alford, William J., Jr.↗
NASA NTRS1946

Wind-tunnel Investigation of End-plate Effects of Horizontal Tails on a Vertical Tail Compared with Available Theory

A vertical-tail model with stub fuselage was tested in combination with various simulated horizontal tails to determine the effect of horizontal-tail span and location on the aerodynamic characteristics of the vertical tail. Available theoretical data on end-plate effects were collected and presented in the form most suitable for design purposes. Reasonable agreement was obtained between the measured and theoretical end-plate effects of horizontal tails on vertical tails, and the data indicated that the end-plate effect was determined more by the location of the horizontal tail than by the span of the horizontal tail. The horizontal tail gave most end-plate effect when located near either tip of the vertical tail and, when located near the base of the vertical tail, the end-plate effect was increased by moving the horizontal tail rearward.

TAIL SURFACES - HINGE MOMENTS↗
NASA NTRS1954

Effect of Horizontal-Tail Span and Vertical Location on the Aerodynamic Characteristics of an Unswept Tail Assembly in Sideslip

An investigation has been conducted in the Langley stability tunnel on a vertical-tail model with a stub fuselage in combination with various horizontal tails to determine the effect of horizontal-tail span and vertical location of the horizontal tail relative to the vertical tail on the aerodynamic characteristics of an unswept tail assembly in sideslip. The results of the investigation indicated that the induced loading carried by the horizontal tail produced a rolling moment about the point of attachment to the vertical tail which was strongly influenced by horizontal-tail span and vertical locations. The greatest effect of horizontal-tail span on the rolling-moment derivative of the complete tail assembly was obtained for horizontal-tail locations near the top of the vertical tail. Span loadings which were reduced to the static-stability derivatives were calculated for each configuration tested by applying the well-known finite-step method used for wings to the intersecting surfaces of the vertical and horizontal tails. The finite-step method provides a simple and effective means of investigating the span loadings of intersecting surfaces.

Riley, Donald R↗
NASA NTRS1977

Tail contribution to the directional aerodynamic characteristics of a 1/6-scale model of the rotor systems research aircraft with a tail rotor

The results are presented of a wind tunnel investigation to determine the tail contribution to the directional aerodynamic characteristics of a 1/6-scale model of the rotor systems research aircraft (RSRA) with a tail rotor. No main rotor was used during the investigation. Data were obtained with and without the tail rotor over a range of sideslip angle and over a range of rotor collective pitch angle. The model with the tail rotor was tested at several advance ratios with and without thrust from the auxiliary thrust engines on the RSRA fuselage. Increasing the space between the tail-rotor hub and the vertical tail reduced the tail-rotor torque required at moderate to high rotor thrust. Increasing the exit dynamic pressure of the auxiliary thrust engines decreases the tail contribution to the static directional stability. The tail-rotor thrust and its interference provide a positive increment to the static directional stability. The tail contribution increases with forward speed. The adverse yawing moment of the airframe would strongly affect the thrust required of the tail rotor when the helicopter is hovering in a crosswind.

Mineck, R. E.↗
NASA NTRS1997

Vertical Tail Buffeting Alleviation Using Piezoelectric Actuators-Some Results of the Actively Controlled Response of Buffet-Affected Tails (ACROBAT) Program

Buffet is an aeroelastic phenomenon associated with high performance aircraft especially those with twin vertical tails. In particular, for the F/A-18 aircraft at high angles of attack, vortices emanating from wing/fuselage leading edge extensions burst, immersing the vertical tails in their wake. The resulting buffet loads on the vertical tails are a concern from fatigue and inspection points of view. Recently, a 1/6-scale F-18 wind-tunnel model was tested in the Transonic Dynamics Tunnel at the NASA Langley Research Center as part of the Actively Controlled Response Of Buffet Affected Tails (ACROBAT) Program to assess the use of active controls in reducing vertical tail buffeting. The starboard vertical tail was equipped with an active rudder and the port vertical tail was equipped with piezoelectric actuators. The tunnel conditions were atmospheric air at Mach 0.10. By using single-input-single-output control laws at gains well below the physical limits of the actuators, the power spectral density of the root strains at the frequency of the first bending mode of the vertical tail was reduced by as much as 60 percent up to angles of attack of 37 degrees. Root mean square (RMS) values of root strain were reduced by as much as 19 percent. The results herein illustrate that buffet alleviation of vertical tails can be accomplished using simple active control of the rudder or piezoelectric actuators. In fact, as demonstrated herein, a fixed gain single input single output control law that commands piezoelectric actuators may be active throughout the high angle-of-attack maneuver without requiring any changes during the maneuver. Future tests are mentioned for accentuating the international interest in this area of research.

Moses, Robert W.↗
NASA NTRS1953

A Transonic Wind-Tunnel Investigation of the Trim and Dynamic Response Characteristics of the Horizontal Tail of a 1/7-Scale Model of the Complete Tail of the Grumman XF10F-1 Airplane

An investigation was made of the trim and dynamic response characteristics of the free-floating horizontal tail of a 1/7-scale model of the complete tail of the Grumman XF10F-1 airplane in the Langley 8-foot transonic tunnel at Mach numbers up to 1.13. The complete tail was mounted in the tunnel on a 3deg conical support body. Various configurations were investigated. A loss in damping of the horizontal tail at transonic speeds was shown by both tunnel and flight tests. The loss in damping extended over a greater Mach number range and the maximum loss occurred at a higher Mach number in the tunnel tests. Large-amplitude oscillations of the horizontal tail of the basic configuration which occurred at low supersonic Mach numbers appeared to be primarily due to the vertical tail of the basic configuration and the interference effects associated with this tail. Secondary factors contributing to the development of the large-amplitude oscillations of the horizontal tail of the basic configuration were probably the loss in damping of the horizontal tail at transonic speeds and the turbulence of the airstream itself.

Luoma, Arvo A.↗
NASA NTRS1989

Vortex control for tail buffet alleviation on a twin-tail fighter configuration

Two aerodynamic concepts proposed for alleviating high-alpha tail buffet characteristics of a LEX (Leading Edge Extension) vortex dominated twin-tail fighter configuration were explored in low-speed tunnel tests on generic models via flow visualizations, 6-component balance measurements and monitoring of tail dynamics. Passive dorsal-fin extensions of the vertical tails, and an active LEX arrangement with up-deflected edge sections were evaluated as independent means of re-structuring the adverse vortical flow environment in the tail region. Each of these techniques successfully reduced the buffet as measured by the root-mean-square of tail accelerometer output, particularly at post-stall angles of attack when the baseline configuration was characterized by high buffet intensity. Used in combination, the two concepts indicated significant tail buffet relief with relatively minor impact on the high-alpha configuration aerodynamics.

Rao, Dhanvada M.↗
NASA NTRS1984

Tissue fluid shift, forelimb loading, and tail tension in tail-suspended rats

The tail suspension model (head-down tilt) simulates hypogravity in terms of musculoskeletal loss in the rat. However, little is known of tissue fluid shifts and body weight distribution in this model. Tissue fluid pressures were measured by wick catheters in 12 Munich-Wistar rats before, during, and after 48 hrs of tail suspension (about 30 deg head-down tilt). Subcutaneous tissue fluid pressure in the neck increased from -2.2 + or - 0.4 (normal horizontal position) to +4.0 + or - 1.5 cm H2O during tail suspension, indicating a cephalic fluid shift and significant edema during head-down tilt. In a separate study, six rats were suspended at 30-70 deg, and forelimb load and tail tension were measured by a balance and force transducer, respectively. Approximately 50 percent of body weight (BW) was loaded on forelimbs at a head-down tilt angle of 30 deg and forelimb load declined linearly to 10 percent BW at 70 deg. Furthermore, tail tension increased from 50 percent BW at 30 deg to 85 percent BW at 70 deg. These results indicate that less than normal loads are applied to forelimbs of rats suspended at angles of less than 30 deg and that the tail bears an increasing proportion of the rat's body weight at head-down tilt angles of less than 30 deg.

Hargens, A. R.↗
NASA NTRS1986

Near-tail reconnection as the cause of cometary tail disconnections

In a cometary tail disconnection event the plasma tail appears to separate from the coma and to accelerate away from it. As this occurs a new tail begins to form. It is proposed that these disconnections arise in a manner analogous to geomagnetic substorms, i.e., by the formation of a strongly reconnecting region in the near tail that forms a magnetic island in the coma and ejects the plasma tail by strengthening the magnetic 'slingshot' within the tail. This reconnection process may be triggered by several different processes, such as interplanetary shocks or variations in the Alfven Mach number.

Russell, C. T.↗
NASA NTRS1958

Wind-Tunnel Investigation of the Low-Speed Characteristics of a 1/8-Scale Model of the Republic XP-91 Airplane with a Vee and a Conventional Tail. Addendum - Characteristics with a Revised Conventional Tail and Drooped Wing Tips

Additional wind-tunnel tests were made of a 1/8-scale model of the Republic XP-91 airplane to determine its characteristics with various modifications. The modifications included a revised conventional tail, revised rocket arrangement, drooped wing tips, and revised landing gear and doors. Tests were also made to determine the effectiveness of the control surfaces of the model with the conventional tail and the effect of changing wing incidence and tail length. The revised rocket arrangement provided a considerable increase in the static directional stability contributed by the vee tail at small angles of yaw. The conventional tail provided a greater static directional stability than the vee tail without increasing the rolling moment due to sideslip. The rolling moment die to sideslip was considerable reduced by either drooped wing tips or open main landing-gear doors. The reduction in rolling moment due to sideslip resulting from the drooped tips was less with the landing-gear doors open than with the doors closed. A change in wing incidence from 0 degrees to 6 degrees reduced the elevator angle required for balance by approximately 6 degrees.

Weiberg, James A.↗