UNT Libraries Government Documents Department - 443 Matching Results
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- Preservation of Documents by Lamination
- From Abstract: "Composition and performance specifications for a cellulose acetate laminating film suitable for a cellulose acetate laminating film suitable for archival use are presented. The properties of polyethylene and polyethylene terephthalate films of interest in connection with their possible use for the protection of documents are discussed."
- Wing Pressure Distributions Over the Lift Range of the Convair XF-92A Delta-Wing Airplane at Subsonic and Transonic Speeds
- Report presenting chordwise pressure distributions measured over the left wing of the Convair XF-92A delta-wing airplane to determine the effect of lift on the wing characteristics at subsonic and transonic Mach numbers. Results regarding the chordwise pressure distributions, wing-section aerodynamic characteristics, spanwise distribution, and elevon-section loads are provided.
- Investigation of Drag and Static Longitudinal and Lateral Stability Characteristics of a 1/15-Scale Model of the Grumman F11F-1F Airplane at Mach Numbers of 1.56, 1.76, 2.06, and 2.53
- Report presenting an investigation in the Langley Unitary Plan wind tunnel to determine the drag and static longitudinal and lateral stability characteristics of a model of the Grumman F11F-1F airplane at Mach numbers 1.56, 1.76, 2.06, and 2.53. The investigation included the effects on performance and stability of modifications, including a wing-root leading-edge fillet and horizontal tails with negative dihedral of 10 degrees and 30 degrees. Information regarding net external minimum drag coefficients, neutral points, directional stability, and positive effective dihedral is provided.
- A Wind-Tunnel Investigation of the Effects of Conical Camber for an Airplane Configuration Having a Triangular Wing of Aspect Ratio 2.2
- Memorandum presenting the results of an investigation directed at determining the effectiveness of various amounts and spanwise extents of conical camber on the aerodynamic characteristics of a wing-body-tail combination employing a triangular wing of aspect ratio 2.2. Five cambered wings were tested, all of which were designed for a Mach number of 1.0. Results regarding drag characteristics and lift and moment characteristics are provided.
- Wind-Tunnel Investigation at High Subsonic Speeds of the Effects on Static Stability Characteristics of Various Modifications to a Swept-Wing Fighter-Type Airplane Model
- Memorandum presenting an investigation at high subsonic speeds of a model of a twin-engine swept-wing fighter-type airplane. The model was tested with several different tail configurations and with several wing and engine inlet modifications. Results regarding pitching-moment characteristics, lift and drag characteristics, and lateral derivatives are provided.
- Experimental Investigation at High Subsonic Speeds of the Rolling-Stability Derivatives of a 1/22 Scale Model of the Republic F-105 Airplane
- Report presenting an investigation of the rolling-stability derivatives for a model of the Republic F-105 airplane over a range of Mach numbers and angles of attack. The model retained damping in roll through the test ranges, but values of the damping varied considerably with angles of attack. Derivatives of yawing moment and lateral force due to rolling generally followed previously indicated trends.
- Aerodynamic Characteristics of a 0.04956-Scale Model of the Convair F-102A Airplane at Mach Numbers of 1.41, 1.61, and 2.01
- "Tests have been made in the Langley 4- by 4-foot supersonic pressure tunnel at Mach numbers of 1.41, 1.61, and 2.01 of various arrangements of a 0.04956-scale model of the Convair F-102A airplane with faired inlets. Tests made of the model equipped with a plain wing, a wing with 6.4 percent conical camber, and a wing with 15 percent conical camber. Body modifications including an extended nose, a modified canopy, and extended afterbody fillets were evaluated" (p. 1).
- Investigation of the Static Stability Characteristics of Five Hypersonic Missile Configurations at Mach Numbers From 2.29 to 4.65
- Report presenting an investigation to determine the static stability characteristics of five hypersonic missile configurations. Testing was performed at a range of Mach and Reynolds numbers. Results regarding the effect of base block, longitudinal stability, directional stability, and Reynolds number effect are provided.
- Flight Investigation at Low Angles of Attack to Determine the Longitudinal Stability and Control Characteristics of a Cruciform Canard Missile Configuration With a Low-Aspect-Ratio Wing and Blunt Nose at Mach Numbers From 1.2 to 2.1
- Report presenting flight testing of a rocket-powered model of a cruciform canard missile configuration with a low-aspect-ratio wing and blunt nose. Results regarding the lift coefficient, dynamic stability, static stability, control effectiveness, and drag are provided.
- Experimental Investigation of Air-Cooled Turbine Blades in Turbojet Engine: 1: Rotor Blades With 10 Tubes in Cooling-Air Passages
- Report presenting an investigation to experimentally determine the effectiveness of air cooling several turbine-blade configurations in a turbojet engine. The results obtained with the first configuration, which was a hollow blade shell with 10 tube inserts, are presented. A description of factors leading to the design are provided as well as the correlated cooled-blade temperatures, solid-blade temperatures, cooling-air-temperature increase through radial passages, and blade failure are provided.
- Preliminary Performance Data Obtained in a Full-Scale Free-Jet Investigation of a Side-Inlet Supersonic Diffuser
- Report discussing an investigation into the performance of several modifications of a side-inlet ramjet engine diffuser. Total-pressure-recovery profiles, Mach number profiles, longitudinal wall static pressure distributions, and variation of the average-static to average-total pressure are presented.
- Analysis of Heat Transfer and Fluid Friction for Fully Developed Turbulent Flow of Supercritical Water With Variable Fluid Properties in a Smooth Tube
- From Summary: "Calculated velocity and temperature distributions, as well as relations among Nusselt number, Reynolds number, and friction factor, are presented."
- Experimental and Theoretical Determination of Forces and Moments on a Store and on a Store- Pylon Combination Mounted on a 45 Degree Swept- Wing-Fuselage Configuration at a Mach Number of 1.61
- Forces and moments of store-pylon combination mounting on swept wing-fuselage configuration in supersonic pressure tunnel. The results of the investigation indicate that the most important source of store-pylon side forces is the pylon itself.
- Performance of an Inlet Having a Variable-angle Two-dimensional Compression Surface and a Fixed-geometry Subsonic Diffuser for Application to Reduced Engine Rotative Speeds- Mach Numbers 0.66, 1.5, 1.7, and 2.0
- Report presenting the performance of a two-dimensional side inlet with a technique of varying compression-surface angle while retaining a fixed-geometry diffuser at several Mach numbers and zero angle of attack. A 12 degree compression ramp was faired into the diffuser contour in this conventional manner. Results regarding the inlet flow field, application to reduced engine speeds, and a inlet performance with a sudden expansion in the diffuser are provided.
- Low-Temperature Chemical Starting of a 200-Pound-Thrust JP-4 - Nitric Acid Rocket Engine Using a Three-Fluid Propellant Valve
- Low-temperature chemical starting of combined JP-4 nitric acid propellant for low-thrust rocket engine using three-fluid propellant valve.
- Use of Highly Reactive Chemical Additives to Improve Afterburner Performance at Altitude
- Memorandum presenting an investigation in an altitude test chamber to evaluate the use of highly reactive chemicals injected into a turbojet afterburner to promote the combustion process, which was inhibited by water vapor from compressor-inlet injection. The chemicals evaluated were commercial hydrogen and aluminum trimethyl. Results regarding the effects of hydrogen injection on afterburner performance and effect of aluminum trimethyl afterburner fuel additive on performance are provided.
- Tabulated Pressure Data for a Series of Controls on a 60 Degree Delta Wing at Mach Numbers of 1.61 and 2.01
- "An investigation has been made at Mach numbers of 1.61 and 2.01 and Reynolds numbers from 1.7 x 10(exp 6) to 7.6 x 10(exp 6) to determine the pressure distributions over a 60 degree delta wing having 20 different control configurations. Measurements were made at angles of attack from 0 to 15 degrees for control deflections from -30 to 30 degrees. This report presents the complete tabulated pressure data for the range of test conditions" (p. 1).
- Off-Design Performance of Divergent Ejectors
- Report presenting an investigation of the off-design performance of fixed- and variable-geometry divergent ejectors. Results regarding fixed geometry and low secondary flow, fixed geometry and high secondary flow, variable geometry and low secondary flow, variable geometry and high secondary flow, and ejectors with full afterburning are provided.
- Performance of a Single Fuel-Vaporizing Combustor With Six Injectors Adapted for Gaseous Hydrogen
- Report presenting an investigation in a single tubular combustor to determine the effectiveness of hydrogen fuel using an annular fuel-vaporizing combustor in a full-scale turbojet engine. Six different fuel-injector designs were investigated. Results regarding the ignition, combustion efficiency, combustor pressure loss, stability of combustion, and best configuration are provided.
- Preliminary investigation of the effects of several seeker-nose configurations on the longitudinal characteristics of a canard-type missile at a Mach number of 1.60
- Report presenting an investigation to determine the effect of several seeker-nose configurations on the static longitudinal stability, canard control characteristics, and lift and drag at Mach number 1.60 of a canard-type ramjet missile with 70 degree delta canard control surfaces and 70 degree delta wings. The tests indicate that, for the most part, the configurations tested exhibited no significant difference in static longitudinal stability or horizontal-canard control effectiveness.
- Heat-transfer and operating characteristics of aluminum forced-convection and stainless-steel natural-convection water-cooled single-stage turbines
- Report presenting testing of two water-cooled turbines, one of aluminum alloy using forced-convection cooling and one of stainless steel using natural-convection cooling, to obtain heat-transfer and general operating data like blade temperatures, coolant-flow rates, and coolant pumping losses. Results regarding outside and inside heat-transfer results, coolant pumping power, general operating results, and practical considerations for both are provided.
- An analysis of the forces and pressure distribution on a wing with the leading edge swept back 37.25 degrees
- Report presenting testing of a semispan model of a wing with the leading edge swept back 37.25 degrees, an aspect ratio of 6.04, and a taper ratio of 0.5 in order to ascertain the compressibility effects on the forces, moments, and surface pressures. Lift, drag, and pitching-moment data along with chordwise distribution of static pressure at five spanwise stations are presented for a range of Mach numbers and a constant Reynolds number. Results regarding force and moment characteristics, critical flow and drag increase at high subsonic Mach numbers, and pressure changes with increasing Mach number are provided.
- A Design Study of Leading-Edge Inlets for Unswept Wings
- Note presenting a practical method, employing a lofting technique, for determining the profile coordinates of an air inlet for the leading edge of an airfoil from formulas which are dependent only on the airfoil coordinates and on the height of the opening. It was found that the base-profile concept of thin-airfoil theory could be applied to a ducted airfoil with satisfactory results. Results regarding design inlets, modified inlets, and end-closure shape are provided.
- Longitudinal characteristics of two 47.7 degree sweptback wings with aspect ratios of 5.1 and 6.0 at Reynolds numbers up to 10 x 10(exp 6)
- Report presenting an investigation of the longitudinal aerodynamic characteristics of a 47.7 degree sweptback wing in the 19-foot pressure tunnel in order to provide large-scale data on relatively high-aspect-ratio sweptback wings. Results regarding pitching-moment characteristics, lift characteristics, lift-drag ratio, and effect of roughness are provided.
- An NACA transonic test section with tapered slots tested at Mach numbers to 1.26
- Report presenting testing of an NACA octagonal transonic slotted test section has been modified to include slots with point origins located at the tunnel aerodynamic minimum and which diverged linearly over a length of 1.5 jet diameters. Pressure distributions along the axis and one wall of the slotted configuration are presented and indicate the attainment of a test region with satisfactory uniform Mach number distributions.
- Preliminary evaluation of the air and fuel specific-impulse characteristics of several potential ram-jet fuels 1: octene-1, aluminum, and aluminum - octene-1 slurries
- Report presenting a preliminary analytical evaluation of the air and fuel specific-impulse characteristics of octene-1, aluminum, and aluminum-octene-1 slurries. The adiabatic combustion flame temperature, combustion equilibrium-gas composition, air specific impulse, and fuel-weight specific impulse are presented for each fuel. Aluminum-octene-1 slurries were found to offer a means of increasing the limited air specific impulse values available with octene-1 or hydrocarbon-type fuels.
- Effect of Fuel Volatility on Performance of Tail-Pipe Burner
- Fuels having Reid vapor pressures of 6.3 and 1.0 pounds per square inch were investigated in a tail-pipe burner on an axial-flow-type turbojet engine at a simulated flight Mach number of 0.6 and altitudes from 20,000 to 45,000 feet. With the burner configuration used in this investigation, having a mixing length of only 8 inches between the fuel manifold and the flame holder, the low-vapor-pressure fuel gave lower combustion efficiency at a given tail-pipe fuel-air ratio. Because the exhaust-nozzle area was fixed, the lower efficiency resulted in lower thrust and higher specific fuel consumption. The maximum altitude at which the burner would operate was practically unaffected by the change in fuel volatility.
- Design and performance of an experimental axial-discharge mixed-flow compressor 3: over-all performance of impeller and supersonic-diffuser combination
- Report presenting an investigation of an axial-discharge impeller in combination with a 16-vaned supersonic diffuser cascade over a range of flow conditions at equivalent tip speeds varying from 800 to 1600 feet per second. Results regarding the overall performance of the combination, starting of diffuser cascade, use of flow bleedoff to aid starting, radial distribution of flow angle, flow characteristics within diffuser, and efficiency of diffuser cascade are provided.
- The Use of Suction to Prevent Shock-Induced Separation in a Nozzle
- "An investigation was made of the use of suction to prevent shock-induced flow separation in a nozzle formed by a 7.5-percent-thick bump on a wall of a channel. Various transverse and longitudinal suction-slot arrangements and suction through porous surfaces were tested. All these devices were effective in preventing separation, and certain suction-slot arrangements reduced the total power loss, including the power lost in the suction process" (p. 1).
- Calculated Lift Distributions of a Consolidated Vultee B-36 and Two Boeing B-47 Airplanes Coupled at the Wing Tips
- Report presenting the calculated lift distributions and associated aerodynamic parameters for a Consolidated Vultee B-36 and two Boeing B-47 airplanes coupled at the wing tips for different angles of attack and deflections of the ailerons. Results regarding lifts, moments, and induced drags and the use of the data for calculating aerodynamic forces and equilibrium conditions are provided.
- Effects of leading-edge devices and trailing-edge flaps on longitudinal characteristics of two 47.7 degree sweptback wings of aspect ratios 5.1 and 6.0 at a Reynolds number of 6.0 x 10(exp 6)
- Report presenting an investigation in the 19-foot pressure tunnel to determine the effects of leading-edge stall-control devices and trailing-edge flaps on the longitudinal stability characteristics of a 47.7 degree sweptback wing that could have aspect ratios of 5.1 and 6.0 by using interchangeable wing tips. The effects of wing fences, roughness, and a fuselage were also determined. Results regarding the lift characteristics and lift-drag ratios are also provided.
- Pressure-Rise and Leakage-Loss Characteristics of a Rotating Cowling
- Report discussing an experimental and analytical investigation in order to study the pressure-rise and leakage-loss characteristics of rotating cowlings. A comparison of the theoretical and experimental results indicated that pressure-rise characteristics can be predicted if internal-flow losses and internal-flow angle at the cowling-vane trailing edge are known.
- An Experimental Investigation at Large Scale of an NACA Submerged Intake and Deflector Installation on the Rearward Portion of a Fuselage
- Report presenting an experimental investigation at low speed to determine the pressure-recovery and drag characteristics of an NACA submerged intake and deflector installation on the rearward portion of the fuselage of a model.
- A preliminary flight investigation of the effects of vortex generators on separation due to shock
- Investigation of an airplane in flight to determine the effectiveness of vortex generators in preventing separation due to compressibility shock at full-scale Reynolds numbers. All of the arrangements of vortex generators tested delayed separation to higher Mach numbers or lift coefficients. More experimentation will be needed to determine the optimum arrangement of vortex generators.
- Lift, Drag, and Pitching Moment of Low-Aspect-Ratio Wings at Subsonic and Supersonic Speeds : Plane Tapered Wing of Aspect Ratio 3.1 with 3-Percent-Thick, Biconvex Section
- "A wing-body combination having a plane tapered wing of aspect ratio 3.1 and 3-percent-thick, biconvex sections in streamwise planes has been investigated at both subsonic and supersonic Mach numbers. The lift, drag, and pitching moment of the model are presented for Mach numbers from 0.60 to 0.925 and 1.20 to 1.90 at a Reynolds number of 2.4 million. Results are also presented for Mach numbers from 0.60 to 0.925 and 1.20 to 1.50 at Reynolds numbers of 1.5 million and 3.8 million" (p. 1).
- Results of Flight Tests to Determine Drag of Parabolic and Cone-Cylinder Bodies of Very Large Fineness Ratios at Supersonic Speeds
- Results of a free-flight investigation at supersonic speeds to determine zero-lift drag of a series of bodies of revolution are presented. Configurations tested included two parabolic bodies with fineness ratios of 17.78 and 24.5 and two 8 degree cone-cylinder bodies with fineness ratios of 17.2 and 21.2. Results of previous tests of similar parabolic bodies but with lower fineness ratios are included in this paper for comparison. All bodies for which data are presented in this paper had a base-to-maximum-diameter ratio of 0.437. Calculated drag coefficients are shown for all bodies for which data are presented. (author).
- Generalized Indical Forces on Deforming Rectangular Wings in Supersonic Flight
- "A method is presented for determining the time-dependent flow over a rectangular wing moving with a supersonic forward speed and undergoing small vertical distortions expressible as polynomials involving spanwise and chordwise distances. The solution for the velocity potential is presented in a form analogous to that for steady supersonic flow having the familiar "reflected area" concept discovered by Evvard. Particular attention is paid to indicial-type motions and results are expressed in terms of generalized indicial forces. Numerical results for Mach numbers equal to 1.1 and 1.2 are given for polynomials of the first and fifth degree in the chordwise and spanwise directions, respectively, on a wing having an aspect ratio of 4" (p. 595).
- Experimental investigation of free-convection heat transfer in vertical tube at large Grashof numbers
- Report presents the results of an investigation conducted to study free-convection heat transfer in a stationary vertical tube closed at the bottom. The walls of the tube were heated, and heated air in the tube was continuously replaced by fresh cool air at the top. The tube was designed to provide a gravitational field with Grashof numbers of a magnitude comparable with those generated by the centrifugal field in rotating-blade coolant passages (10(8) to 10(13)). Local heat-transfer coefficients in the turbulent-flow range and the temperature field within the fluid were obtained.
- Comparison of performance of experimental and conventional cage designs and materials for 75-millimeter-bore cylindrical roller bearings at high speed
- From Summary: "The results of two investigations, one to determine the relative merits of four experimental and two conventional design 75-millimeter-bore (size 215) cylindrical roller bearings and one to determine the relative merits of nodular iron and bronze as cage materials for this size and type of bearing, are presented in this report. Nine test bearings were operated over a range of dn values (product of bearing bore in mm and shaft speed in r.p.m) from 0.3 x 10(6) to 2.3 x 20(6), radial loads for 7 to 1613 pounds, and oil flows from 2 to 8 pounds per minute with a single-jet circulatory oil feed. Of the six bearings used to evaluate designs, four were experimental types with outer-race-riding cages and inner-race-guided rollers, and two were conventional types, one with outer-race-guided rollers and cage and one with inner-race-guided rollers and cage."
- Generalized Theory for Seaplane Impact
- "The motions, hydrodynamic loads, and pitching moments experienced by V-bottom seaplanes during step-landing impacts are analyzed and the theoretical results are compared with experimental data. In the analysis, the primary flow about the immersed portion of a keeled hull or float is considered to occur in transverse flow planes and the concept of virtual mass is applied to determined the reaction of the water to the motions of the seaplane. The entire immersion process is analyzed from the instant of initial contact until the seaplane rebounds from the water surfaces" (p. 953).
- Spectrum of turbulence in a contracting stream
- The spectrum concept is employed to study the selective effect of a stream contraction on the longitudinal and lateral turbulent velocity fluctuations of the stream. By a consideration of the effect of the stream contraction on a single plane sinusoidal disturbance wave, mathematically not dissimilar to a triply periodic disturbance treated by G. I. Taylor, the effect on the spectrum tensor of the turbulence and hence on the correlation tensor is determined.
- Application of a channel design method to high-solidity cascades and tests of an impulse cascade with 90 degrees of turning
- From introduction: "A technique for application of the channel design methods of reference 11 to the design of high-solidity cascades with prescribed velocity distributions as a function of arc length along the blade-element profiles is presented herein."
- Hydrodynamic impact of a system with a single elastic mode 2: comparison of experimental force and response with theory
- From Summary: "Hydrodynamic impact tests were made on an elastic model approximating a two-mass spring system to determine experimentally the effects of structural flexibility on the hydrodynamic loads encountered during seaplane landing impacts and to correlate the results with theory. A flexible seaplane was represented by a two-mass spring system consisting of a rigid prismatic float connected to a rigid upper mass by an elastic structure. The model had a ratio of sprung mass to hull mass of 0.6 and a natural frequency of 3.0 cycles per second. The tests were conducted in smooth water at fixed trims and included both high and low flight-path angles and a range of velocity. Theoretical and experimental comparisons indicated that the theoretical results agreed well with the experimental results."
- Experimental and theoretical studies of area suction for the control of the laminar boundary layer on an NACA 64A010 airfoil
- From Summary: "A low-turbulence wind-tunnel investigation was made of an NACA 64A010 airfoil having a porous surface to determine the reduction in section total-drag coefficient that might be obtained at large Reynolds numbers by the use of suction to produce continuous inflow through the surface of the airfoil (area suction). In addition to the experimental investigation, a related theoretical analysis was made to provide a basis of comparison for the test results."
- Methods for obtaining desired helicopter stability characteristics and procedures for stability predictions
- Part I of this report presents a brief review of methods available to the helicopter designer for obtaining desired stability characteristics by modifications to the airframe design. The discussion is based on modifications made during the establishment of flying-qualities criteria and includes sample results of theoretical studies of additional methods. The conclusion is reached that it is now feasible to utilize combinations of methods whereby stability-parameter values are realized which in turn provide the desired stability characteristics. Part II reviews some of the methods of predicting rotor stability derivatives. The procedures by which these rotor derivatives are employed to estimate helicopter stability characteristics have been summarized.
- Blowing-type boundary-layer control as applied to the trailing-edge flaps of a 35 degree swept-wing airplane
- A wind-tunnel investigation was made to determine the effects on the aerodynamic characteristics of a 35 degree swept-wing airplane of applying blowing-type boundary-layer control to the trailing-edge flaps. Flight tests of a similar airplane were then conducted to determine the effects of boundary-layer control on the handling qualities and operation of the airplane, particularly during landing and take-off. The wind-tunnel and flight tests indicated that blowing over the flaps produced large increases in flap lift increment, and significant increases in maximum lift. The use of blowing permitted reductions in the landing approach speeds of as much as 12 knots.
- Secondary flows and boundary-layer accumulations in turbine nozzles
- An investigation of secondary-flow loss patterns originating in three sets of turbine nozzle blade passages was conducted by means of flow-visualization studies and detailed flow measurements. For all cases, high loss values were measured in the fluid downstream of the corners formed by the suction surfaces of the blades and the shrouds, and these losses were accompanied by discharge-angle deviations from design values. Despite the size of the loss regions and angle gradients, over-all mass-average blade efficiencies were of the order of 0.99 and 0.98 and, therefore, are not a good index of blade performance.
- Preliminary Internal Performance Data for a Variable-Ejector Assembly on the XJ79-GE-1 Turbojet Engine, 2, Afterburning Configurations
- Internal performance of an XJ79-GE-1 variable ejector was experimentally determined with the primary nozzle in two representative after-burning positions. Jet-thrust and air-handling data were obtained in quiescent air for 4 selected ejector configurations over a wide range of secondary to primary airflow ratios and primary-nozzle pressure ratios. The experimental ejector data are presented in both graphical and tabulated form.
- Investigation of a Half-Conical Scoop Inlet Mounted at Five Alternate Circumferential Locations Around a Circular Fuselage: Pressure-Recovery Results at a Mach Number 2.01
- The effects of inlet circumferential position around the fuselage on the characteristics of a half-conical scoop inlet having a 24.6deg half-angle cone have been investigated in the langley 4- by 4-foot supersonic pressure tunnel. Pressure-recovery results have been obtained at a Mach number of 2.01 for a fixed boundary-layer-bleed height which was 60 percent of the boundary-layer thickness at an angle of attack of 0deg, and for cowling position parameters of 42.4deg and 38.0deg. inlet had a capture area equal to 24.9 percent of the basic-fuselage frontal area. The angle of attack was varied from 0deg to 12deg.
- An Exploratory Investigation of Some Types of Aeroelastic Instability of Open and Closed Bodies of Revolution Mounted on Slender Struts
- "Aeroelastic instability phenomena of isolated open and closed rigid bodies of revolution free to move under elastic restraint have been investigated experimentally at low speeds by means of models suspended at zero angles of attack and yaw on slender flexible struts from a wind tunnel ceiling. Three types of instability were observed - flutter similar to classical bending-torsion flutter, divergence, and an uncoupled oscillatory instability which consists in nonviolent continuous or intermittent small-amplitude oscillations involving only angular deformations. The speeds at which this oscillatory instability starts were found to be as low as about one-third of the speed at flutter or divergence and to depend on the shape of the body, particularly that of the afterbody, and on the relative location of the elastic axis" (p. 1).