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At least 127 records · Page 7

Apparatus and method for improving spin recovery on aircraft

Previous research on airplane spinning and recovery has shown that at potential spin conditions (high angles of attack with rotation) the horizontal tail, depending upon its location, can create a wake about the vertical tail and rudder which can adversely affect airplane spin and recovery characteristics. Many methods of altering the tail geometry to modify these interference effects were investigated for improving airplane spin and recovery characteristics. Examples of changes includes relocation of the horizontal tail, increasing control surface travel, and use of a 'flip tail' that can be rotated to extreme angles for spin recovery. A device is provided which improves the spin recovery characteristics of aircraft which involves attaching the horizontal tail of the aircraft to the aircraft such that a gap remains between the root end of each horizontal tail section and the fuselage or vertical tail of the aircraft. The gaps measure between about 15 and 30 percent of the tail semispan. The gaps may be covered by shields which are released should a spin occur.

Stough, H. Paul, II↗

Some theoretical considerations of a stall proof airplane

For the stall proof airplane there should be a stabilizing pitching moment below the stall angle of attack of sufficient amount to prevent the attainment of the stall angle of attack which cannot be over-ridden by control deflections. This paper presents (1) a development of the moment equations to show the theoretical considerations of a stall proof airplane and (2) the nonlinear moment characteristics that must be obtained to satisfy the stall proof requirements. In addition, it is shown that an aerodynamic spoiler located on the under surface of the horizontal tail can be designed to meet these requirements of a stall proof airplane. Wind tunnel results are shown to validate assumptions and predictions.

Chevalier, H. L.↗

Effect of thrust reverser operation on the lateral-directional characteristics of a three-surface F-15 model at transonic speeds

An investigation was conducted in the Langley 16 Foot Transonic Tunnel to determine the lateral directional aerodynamic characteristics of a fully metric 0.04 scale model of the F-15 three surface configuration (canards, horizontal tails) with twin two dimensional nozzles and twin axisymmetric nozzles installed. The effects of two dimensional nozzle in flight thrust reversing and rudder deflection were also determined. Test data were obtained at static conditions and at Mach numbers from 0.60 to 1.20 over an angle of attack range from -2 deg to 15 deg. Reynolds number varied from 2.6 million to 3.8 million. Angle of sideslip was set at approximately 0 deg and -5 deg for all configurations and at -10 deg for selected configurations.

Bare, E. A.↗

Pressure-distribution investigation of an N.A.C.A. 0009 airfoil with a 50-percent-chord plain flap and three tabs

Pressure-distribution tests of an N.A.C.A. 0009 airfoil with a 50-percent-chord plain flap and three plain tabs, having chords 10, 20, and 30 percent of the flap chord, were made in the N.A.C.A. 4- by 6- foot vertical tunnel. The tests supplied aerodynamic section data that may be applied to the design of horizontal and vertical tail surfaces. The results are presented as resultant-pressure diagrams for the airfoil with the flap and the 20-percent-chord tab. Plots are also given of increments of normal-force and hinge-moment coefficients for the airfoil, the flap, and the three tabs. The experimental results and values computed by analytical methods are in good agreement for small flap and tab deflections. The results of the tests indicated that the effectiveness of all three tab sizes in reducing flap hinge moments decreased with increasing flap deflection.

Street, William G↗

Pressure-distribution investigation on an NACA 0009 airfoil with a 30-percent-chord plain flap and three tabs

Pressure-distribution tests of an NACA 0009 airfoil with a 30-percent-chord plain flap and three plain tabs, having chords 10, 20, and 30 percent of the flap chord, were made. The purpose of these tests was to continue an investigation to supply structural and aerodynamic section data that may be applied to the design of horizontal and vertical tail surfaces. The results are presented as diagrams of resultant pressures and of resultant-pressure increments for the airfoil with the flap and the 20-percent-chord tab. Increments of normal-force and hinge-moment coefficients for the airfoil, the flap, and the three tabs are also given. At all unstalled flap and tab deflections, the experimental distributions agree well with those calculated by an analytical method. The agreement is poor, however, then the stalled or the unstalled condition of the flap or tab deflected alone was changed to an unstalled or stalled condition by the simultaneous deflection of both the flap and the tab.

Ames, Milton B↗

Pressure-distribution investigation of an NACA 0009 airfoil with an 80-percent-chord plain flap and three tabs

Pressure-distribution tests of an NACA 0009 airfoil with an 80-percent-chord plain flap and three plain tabs, having chord of 10, 20, and 30 percent of the flap chord, were made. Section data suitable for application to the design of horizontal and vertical tail surfaces were obtained. Resultant-pressure diagrams for the airfoil with the flap and the 20-percent-chord tab are presented. Plots are also given of increments of normal-force and hinge-moment coefficients for the airfoil, the flap, and the three tabs. A comparison of some characteristic slopes for the 30-, the 50-, and the 80-percent-chord flaps, tested in the general investigation of plain flaps for control surfaces, is included. Section aerodynamic and load data have been made available for a wide range of flap and a tab chords to be used on an NACA 0009 airfoil or on other conventional sections.

Ames, Milton B , Jr↗

Effect of Target-type Thrust Reverser on Transonic Aerodynamic Characteristics of a Single-engine Fighter Model

A brief investigation of a target-type thrust reverser on a single-engine fighter model has been conducted in the Langley 16-foot transonic tunnel at Mach numbers from 0.20 to 1.05.At Mach numbers of 0.80, 0.92, and 1.05, a hydrogen peroxide turbojet-engine simulator was operated with the thrust reverser extended. The angle of attack was varied from 0 degrees to 5 degrees at these Mach numbers. The Reynolds number of the free stream, based on the mean aerodynamic chord, was about 5 x 10(6). It was estimated that reversed jet operations separated the model boundary-layer flow over the upper surface of the horizontal tail and upper part of the afterbody. This resulted in a positive pitch increment due to reversed jet operation. Jet-on operation also tended to stabilize the severe lateral oscillations which occurred with the reverser extended and the jet off. It appeared that these jet-off oscillations were the result of an alternating separation and reattachment of the flow on the rearmost portions of the fuselage afterbody.

Swihert, John M↗

Ice Accretion Calculations for a Commercial Transport Using the LEWICE3D, ICEGRID3D and CMARC Programs

Collection efficiency and ice accretion calculations were made for a commercial transport using the NASA Lewis LEWICE3D ice accretion code, the ICEGRID3D grid code and the CMARC panel code. All of the calculations were made on a Windows 95 based personal computer. The ice accretion calculations were made for the nose, wing, horizontal tail and vertical tail surfaces. Ice shapes typifying those of a 30 minute hold were generated. Collection efficiencies were also generated for the entire aircraft using the newly developed unstructured collection efficiency method. The calculations highlight the flexibility and cost effectiveness of the LEWICE3D, ICEGRID3D, CMARC combination.

Bidwell, Colin S.↗

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↗

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↗

Aerodynamic Characteristics of a Canard and an Outboard-Tail Airplane Model at High Subsonic Speeds

An investigation has been made in the Langley high-speed 7- by 10-foot tunnel through a range of Mach numbers from 0.60 to 0.95 of the static longitudinal and lateral stability and control characteristics of a canard airplane configuration and an outboard-tail configuration. The canard model had a twisted wing with approximately 67 deg of sweepback and an aspect ratio of 2.91 and was tested with three trapezoidal canard surfaces having ratios of exposed area to wing area of 0.032, 0.076, and 0.121. The canard model had a single body-mounted vertical tail. The outboard-tail model had its horizontal- and vertical-tail surfaces mounted on slender bodies attached to the wing tips and located to the rear and outboard of the 67 deg sweptback wing of aspect ratio 1.00. The data, which are presented with limited analysis, provide information at high subsonic speeds on these two types of high-speed airplanes which have previously been tested at supersonic speeds and reported in NACA RM L58BO7 and NACA RM L58E20.

Fournier, Paul G.↗

Tri-Rotor Aircraft Capable of Vertical Takeoff and Landing and Transitioning to Forward Flight

Systems, methods, and devices provide a vehicle, such as an aircraft, with rotors configured to function as a tri-copter for vertical takeoff and landing ("VTOL") and a fixed-wing vehicle for forward flight. One rotor may be mounted at a front of the vehicle fuselage on a hinged structure controlled by an actuator to tilt from horizontal to vertical positions. Two additional rotors may be mounted on the horizontal surface of the vehicle tail structure with rotor axes oriented vertically to the fuselage. For forward flight of the vehicle, the front rotor may be rotated down such that the front rotor axis may be oriented horizontally along the fuselage and the front rotor may act as a propeller. For vertical flight, the front rotor may be rotated up such that the front rotor axis may be oriented vertically to the fuselage, while the tail rotors may be activated.

North, David D.↗

Effect of nozzle and vertical-tail variables on the performance of a 3-surface F-15 model at transonic Mach numbers

An investigation was conducted in the Langley 16 foot transonic tunnel to determine the longitudinal aerodynamic characteristics of twin two dimensional nozzles and twin baseline axisymmetric nozzles installed on a fully metric 0.047 scale model of the F-15 three surface configuration (canards, wing, horizontal tails). The effects on performance of two dimensional nozzle in flight thrust reversing, locations and orientation of the vertical tails, and deflections of the horizontal tails were also determined. Test data were obtained at static conditions and at Mach numbers from 0.60 to 1.20 over an angle of attack range from -2 deg to 15 deg. Nozzle pressure ratio was varied from jet off to about 6.5.

Pendergraft, O. C., Jr.↗

Flight Tests on U.S.S. Los Angeles. Part I : Full Scale Pressure Distribution Investigation

The primary purpose of this investigation was to obtain simultaneous data on the loads and stress experience in flight by the U. S. S. Los Angeles which could be used in rigid airship structure design. A secondary object of the investigation was to determine the turning and drag characteristics of the airship. The aerodynamic loading was obtained by measuring the pressure at 95 locations on the tail surfaces, 54 on the hull, and 5 on the passenger car. These measurements were made during a series of maneuvers consisting of turns and reversals in smooth air and during a cruise in rough air which was just short of squall proportions. The results of the pressure measurements on the hull indicate that the forces on the forebody of an airship are relatively small. The tail surface measurements show conclusively that the forces caused by gusts are much greater than those caused by horizontal maneuvers. In this investigation the tail surface loadings caused by gusts closely approached the designed loads of the tail structure. The turning and drag characteristics will be reported in separate reports.

De France, S J↗