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On the flying qualities of helicopters (open access)

On the flying qualities of helicopters

Report presenting the flying qualities problems of current helicopters, including instability with angle of attack in forward flight, control sensitivity in hovering, and control forces following control movement in maneuvers. Some possible solutions to these issues are presented.
Date: January 27, 1949
Creator: Reeder, John P. & Gustafson, F. B.
System: The UNT Digital Library
Low-Speed Investigation of a Small Triangular Wing of Aspect Ratio 2.0 1 The Effect of Combination With a Body Revolution and Height Above a Ground Plane (open access)

Low-Speed Investigation of a Small Triangular Wing of Aspect Ratio 2.0 1 The Effect of Combination With a Body Revolution and Height Above a Ground Plane

Memorandum presenting low-speed wind-tunnel test conducted of a triangular wing of aspect ratio 2.0 with a symmetrical double-wedge section with a maximum thickness of 5 percent of the chord at 20 percent of the chord. The wing was also tested in the presence of a ground plane. Results regarding isolated wing and wing-body combinations, split-flap effectiveness, and ground effect are provided.
Date: August 27, 1948
Creator: Rose, Leonard M.
System: The UNT Digital Library
High-speed aerodynamic characteristics of horn and overhang balances on a full-scale elevator (open access)

High-speed aerodynamic characteristics of horn and overhang balances on a full-scale elevator

Report presenting high-speed wind tunnel testing of horn- and overhang-balance elevators on a full-scale, semispan, horizontal tail. The effects of unshielding the horn and unsealing the overhang were investigated. Results regarding aerodynamic characteristics, distortions of the tail, and critical Mach numbers are provided.
Date: February 27, 1948
Creator: Cleary, Joseph W. & Krumm, Walter J.
System: The UNT Digital Library
Wind-tunnel investigation of horizontal tails. 5: 45 degree swept-back plan form of aspect ratio 2 (open access)

Wind-tunnel investigation of horizontal tails. 5: 45 degree swept-back plan form of aspect ratio 2

Report presenting the results of a wind-tunnel investigation of the low-speed aerodynamic characteristics of a 45 degree sweptback horizontal-tail model of aspect ratio 2 and a comparison of these results with results for a model of the same aspect ratio with an unswept hinge line. Results regarding the lift and hinge-moment parameters, static longitudinal stability, effect of Reynolds number, effect of standard roughness, effect of removing elevator nose seal, and visualization of the air flow are provided.
Date: September 27, 1949
Creator: Dods, Jules B., Jr.
System: The UNT Digital Library
Flight Investigation From High Subsonic to Supersonic Speeds to Determine the Zero-Lift Drag of a Transonic Research Vehicle Having Wings of 45 Degree Sweepback, Aspect Ratio 4, Taper Ratio 0.6, and NACA 65A006 Airfoil Sections (open access)

Flight Investigation From High Subsonic to Supersonic Speeds to Determine the Zero-Lift Drag of a Transonic Research Vehicle Having Wings of 45 Degree Sweepback, Aspect Ratio 4, Taper Ratio 0.6, and NACA 65A006 Airfoil Sections

Report presenting rocket-powered flight tests from high subsonic to supersonic speeds and at high Reynolds numbers to determine the zero-lift drag of a transonic wing-body and body-alone configuration. The configuration tested featured a wing of 45 degree sweepback, aspect ratio 4, taper ratio 0.6, and an NACA 65A006 airfoil section, and a body of fineness ratio of 10 and a frontal area equal to 6.06 percent of the wing-plan-form area.
Date: October 27, 1949
Creator: Katz, Ellis
System: The UNT Digital Library
Experimental Pressure Distributions Over Wing Tips at Mach Number 1.9 1 - Wing Tip With Subsonic Leading Edge (open access)

Experimental Pressure Distributions Over Wing Tips at Mach Number 1.9 1 - Wing Tip With Subsonic Leading Edge

An investigation was conducted at a Mach number of 1.91 to determine spanwise pressure distribution over a wing tip in a region influenced by a sharp subsonic leading edge swept back at 70 degrees. Except for pressure distribution on the top surface in the immediate vicinity of the subsonic leading edge, the maximum difference between linearized theory and experimental data was 2 1/2 percent (of free-stream dynamic pressure) for angles of attack up to 4 degrees and 7 percent for angles of attack up to 8 degrees. Pressures on the top surface nearest the subsonic edge indicated local expansions beyond values predicted by linearized theory.
Date: January 27, 1949
Creator: Jagger, James M. & Mirels, Harold
System: The UNT Digital Library
Aerodynamic Characteristics of Several NACA Airfoil Sections at Seven Reynolds Numbers From 0.7 X 10(Exp 6) to 9.0 X 10(Exp 6) (open access)

Aerodynamic Characteristics of Several NACA Airfoil Sections at Seven Reynolds Numbers From 0.7 X 10(Exp 6) to 9.0 X 10(Exp 6)

Report presenting an investigation of the two-dimensional aerodynamic characteristics of several NACA airfoil sections at four Reynolds numbers. Results regarding the minimum drag, maximum lift, lift-curve slope, and angle of zero lift and pitching moment are provided.
Date: May 27, 1948
Creator: Loftin, Laurence K., Jr. & Poteat, M. Irene
System: The UNT Digital Library
Lateral-Control Investigation on a 37 Degree Sweptback Wing of Aspect Ratio 6 at a Reynolds Number of 6,800,000 (open access)

Lateral-Control Investigation on a 37 Degree Sweptback Wing of Aspect Ratio 6 at a Reynolds Number of 6,800,000

Memorandum presenting the low-speed lateral-control characteristics of a 37 degree sweptback semispan wing of aspect ratio 6 and NACA 64-series airfoil sections in the 19-foot pressure tunnel. The investigation included the measurement of the hinge-moment characteristics of an aileron and the rolling-effectiveness characteristics of the aileron and two configurations of spoilers.
Date: January 27, 1949
Creator: Graham, Robert R. & Koven, William
System: The UNT Digital Library
High-Speed Aerodynamic Characteristics of a Lateral-Control Model 1: NACA 0012-64 Section with 20-Percent-Chord Plain Aileron and 0 Degree and 45 Degrees Sweepback (open access)

High-Speed Aerodynamic Characteristics of a Lateral-Control Model 1: NACA 0012-64 Section with 20-Percent-Chord Plain Aileron and 0 Degree and 45 Degrees Sweepback

Memorandum describing wind-tunnel tests made to determine the aerodynamic characteristics of a 20-percent-chord plain aileron on a semispan wing with the NACA 0012-64 section. The report includes the results of tests of the wing unswept and swept back 45 degrees and with the aileron deflected from 0 to 10 degrees.
Date: September 27, 1948
Creator: Anderson, Joseph L. & Krumm, Walter J.
System: The UNT Digital Library
Effects of Mach number and sweep on the damping-in-roll characteristics of wings of aspect ratio 4 (open access)

Effects of Mach number and sweep on the damping-in-roll characteristics of wings of aspect ratio 4

An investigation of the damping-in-roll characteristics of three wings with an aspect ratio of 4, a taper ratio of 0.6, three sweep angles at the quarter chord line, and the NACA 65A006 section as determined through a range of Mach numbers and angles of attack.
Date: June 27, 1949
Creator: Kuhn, Richard E. & Myers, Boyd C., II
System: The UNT Digital Library
Theoretical comparison of several methods of thrust augmentation for turbojet engines (open access)

Theoretical comparison of several methods of thrust augmentation for turbojet engines

"A theoretical investigation of tail-pipe burning, water injection at the compressor inlet, combination tail-pipe burning plus water injection, bleedoff, and rocket-assist methods thrust augmentation for turbojet engines was made for an engine representative of those in current use. The effect of augmented liquid ratio on augmented thrust ratio and the effects of altitude and flight Mach number on the performance of various methods were determined. The additional take-off weight involved by the use of the different thrust augmentation methods, as well as the effect of the various thrust augmentation methods on the range of a representative aircraft was also investigated" (p. 727).
Date: October 27, 1948
Creator: Hall, Eldon W. & Wilcox, E. Clinton
System: The UNT Digital Library
Bending of Rectangular Plates With Large Deflections (open access)

Bending of Rectangular Plates With Large Deflections

"The solution of Von Karman's fundamental equations for large deflections of plates is presented for the case of a simply supported rectangular plate under combined edge compression and lateral loading. Numerical solutions are given for square plates and for rectangular plates with a width-span ratio of 3:1. The effective widths under edge compression are compared with effective widths according to Von Karman, Bengston, Marguerre, and Cox and with experimental results by Ramberg, Mcpherson, and Levy" (p. 1).
Date: May 27, 1941
Creator: Levy, Samuel
System: The UNT Digital Library
The Theory of Propellers 1: Determination of the Circulation Function and the Mass Coefficient for Dual-Rotating Propellers (open access)

The Theory of Propellers 1: Determination of the Circulation Function and the Mass Coefficient for Dual-Rotating Propellers

"Values of the circulation function have been obtained for dual-rotating propellers. Numerical values are given for four, eight, and twelve-blade dual-rotating propellers and for advance ratios from 2 to about 6. In addition, the circulation function has been determine for single-rotating propellers for the higher values of the advance ratio. The mass coefficient, another quantity of significance in propeller theory, has been introduced" (p. 35).
Date: May 27, 1944
Creator: Theodorsen, Theodore
System: The UNT Digital Library
Bending and shear stresses developed by the instantaneous arrest of the root of a moving cantilever beam (open access)

Bending and shear stresses developed by the instantaneous arrest of the root of a moving cantilever beam

A theoretical and experimental investigation has been made of the behavior of a cantilever beam in transverse motion when its root is suddenly brought to rest. Equations are given for determining the stresses, the deflections, and the accelerations that arise in the beam as a result of the impact. The theoretical equations, which have been confirmed experimentally, reveal that, at a given percentage of the distance from root to tip, the bending stresses for a particular mode are independent of the length of the beam, whereas the shear stresses vary inversely with the length.
Date: September 27, 1944
Creator: Stowell, Elbridge Z.; Schwartz, Edward B. & Houbolt, John C.
System: The UNT Digital Library
Effect of Maximum Cruise-Power Operation at Ultra-Lean Mixture and Increased Spark Advance on the Mechanical Condition of Cylinder Components (open access)

Effect of Maximum Cruise-Power Operation at Ultra-Lean Mixture and Increased Spark Advance on the Mechanical Condition of Cylinder Components

"A continuous 50-hour test was conducted to determine the effect of maximum cruise-power operation at ultra-lean fuel-air mixture and increased spark advance on the mechanical conditions of cylinder components. The test was conducted on a nine-cylinder air-cooled radial engine at the following conditions:brake horsepower, 750; engine speed, 1900 rpm; brake mean effective pressure, 172 pounds per square inch; fuel-air ratio, 0.052; spark advance, 30 deg B.T.C.; and maximum rear-spark-plug-bushing temperature, 400 F. In addition to the data on corrosion and wear, data are presented and briefly discussed on the effect of engine operation at the conditions of this test on economy, knock, preignition, and mixture distribution" (p. 1).
Date: September 27, 1945
Creator: Harris, Herbert B.; Duffy, Robert T. & Erwin, Robert D., Jr.
System: The UNT Digital Library
Dynamics of a turbojet engine considered as a quasi-static system (open access)

Dynamics of a turbojet engine considered as a quasi-static system

From Summary: "A determination of the dynamic characteristics of a typical turbojet engine with a centrifugal compressor, a sonic-flow turbine-nozzle diaphragm, and fixed area exhaust nozzle is presented. A generalized equation for transient behavior of the engine was developed; this equation was then verified by calculations using compressor and turbine performance charts extrapolated from equilibrium operating data and by experimental data obtained from an engine operated under transients in fuel flow."
Date: July 27, 1949
Creator: Otto, Edward W. & Taylor, Burt L., III
System: The UNT Digital Library
Preliminary Investigation of a New Type of Supersonic Inlet (open access)

Preliminary Investigation of a New Type of Supersonic Inlet

"A supersonic inlet with supersonic deceleration of the flow entirely outside of the inlet is considered. A particular arrangement with fixed geometry having a central body with a circular annular intake is analyzed, and it is shown theoretically that this arrangement gives high pressure recovery for a large range of Mach number and mass flow and therefore is practical for use on supersonic airplanes and missiles. For some Mach numbers the drag coefficient for this type of inlet is larger than the drag coefficient for the type of inlet with supersonic compression entirely inside, but the pressure recovery is larger for all flight conditions" (p. 1).
Date: November 27, 1946
Creator: Ferri, Antonio & Nucci, Louis M.
System: The UNT Digital Library
Method of Estimating the Minimum Size of a Tail or Wing-Tip Parachute for Emergency Spin Recovery of an Airplane (open access)

Method of Estimating the Minimum Size of a Tail or Wing-Tip Parachute for Emergency Spin Recovery of an Airplane

Paper presents a method for estimating the size of a tail or wing-tip parachute required for satisfactory emergency recovery of airplanes during spin demonstrations. The method was developed from an analysis of the results of investigations conducted in the 20-foot free-spinning tunnel with dynamically scaled models of 23 airplanes. Results regarding the conventional airplane, tailless aircraft, and estimation of shock load developed by the opening of the spin-recovery parachute.
Date: October 27, 1948
Creator: Malvestuto, Frank S., Jr.
System: The UNT Digital Library
Method of Estimating the Minimum Size of a Tail or Wing-Tip Parachute for Emergency Spin Recovery of an Airplane (open access)

Method of Estimating the Minimum Size of a Tail or Wing-Tip Parachute for Emergency Spin Recovery of an Airplane

Report presenting a method for estimating the size of a tail or wing-tip parachute required for satisfactory emergency recovery of airplanes during spin demonstrations. A comparison of the parachute sizes estimated by the method versus information obtained during experimentation indicated satisfactory agreement. Information about the calculations for a conventional and a tailless airplane is provided.
Date: October 27, 1948
Creator: Malvestuto, Frank S., Jr.
System: The UNT Digital Library
Force Test of a 1/5-Scale Model of the Type GB-5 Controllable Glide Bomb (open access)

Force Test of a 1/5-Scale Model of the Type GB-5 Controllable Glide Bomb

Report presenting information regarding the development of a type GB-5 controllable glide bomb equipped with a target-seeking device. The model was tested on the six-component balance in order to measure the stability and control characteristics of the bomb in its original condition and with various modifications. Results regarding the effect of end plates on dihedral parameter, effect of vertical-tail arrangement on directional stability, aileron tests, and glide-path control are provided.
Date: March 27, 1944
Creator: Pitkin, Marvin
System: The UNT Digital Library
Reduction of Fuel-Vapor Loss by Omitting Some of the Fuel Constituents Normally Lost During Flight (open access)

Reduction of Fuel-Vapor Loss by Omitting Some of the Fuel Constituents Normally Lost During Flight

Report discussing an investigation to determine the effect of omitting some of the fuel constituents in AN-F-28 Amendment 2 fuel that are normally lost in flight on fuel-vapor loss. Removing the components was found to decrease the fuel-vapor loss and increase the critical altitudes.
Date: August 27, 1945
Creator: Stone, Charles S. & Kramer, Walter E.
System: The UNT Digital Library
F-3 and F-4 Engine Tests of Several High-Antiknock Components of Aviation Fuel (open access)

F-3 and F-4 Engine Tests of Several High-Antiknock Components of Aviation Fuel

Report discussing testing on triptane, hot-acid octane, diisopropyl, neohexane, mixed xylenes, cumene, benzene, toluene, and methyl tert-butyl ether in several blends to determine their knock-limited performance data in F-3 and F-4 engines at standard operating conditions. All of the blending agents examined were found to be usable, with concentrations varying depending on various thermodynamic properties.
Date: November 27, 1944
Creator: Imming, Harry S.; Barnett, Henry C. & Genco, Russell S.
System: The UNT Digital Library
Calculated Condenser Performance for a Mercury-Turbine Power Plant for Aircraft (open access)

Calculated Condenser Performance for a Mercury-Turbine Power Plant for Aircraft

"As part of an investigation of the application of nuclear energy to various types of power plants for aircraft, calculations have been made to determine the effect of several operating conditions on the performance of condensers for mercury-turbine power plants. The analysis covered 8 range of turbine-outlet pressures from 1 to 200 pounds per square inch absolute, turbine-inlet pressures from 300 to 700 pounds per square inch absolute,and a range of condenser cooling-air pressure drops, airplane flight speeds, and altitudes. The maximum load-carrying capacity (available for the nuclear reactor, working fluid, and cargo) of a mercury-turbine powered aircraft would be about half the gross weight of the airplane at a flight speed of 509 miles per hour and an altitude of 30,000 feet" (p. 1).
Date: August 27, 1948
Creator: Doyle, Ronald B.
System: The UNT Digital Library
Characteristics of a Hot Jet Discharged from a Jet-Propulsion Engine (open access)

Characteristics of a Hot Jet Discharged from a Jet-Propulsion Engine

From Summary: "An investigation of a heated jet was conducted in conjunction with tests of an axial-flow jet-propulsion engine in the Cleveland altitude wind tunnel. Pressure and temperature surveys were made across the jet 10 and 15 feet behind the jet-nozzle outlet of the engine. Surveys were obtained at pressure altitudes of 10,000, 20,000, 30,000, and 40,000 feet with test-section velocities from 30 to 110 feet per second and test-section temperatures from 60 F to -50 F. From measurements taken throughout the operable range of engine speeds, tail-pipe outlet temperatures from 500 F to 1250 F and jet velocities from 400 to 2200 feet per second were obtained."
Date: December 27, 1946
Creator: Fleming, William A.
System: The UNT Digital Library