Report presenting tests in the two-dimensional low-turbulence pressure tunnel to study the interference effects of various pusher-propeller shaft-housing combinations on a low-drag airfoil. Thirty different combinations were tested, variations being made in shaft size, shape, angle, and fillet.
"In connection with studies of airfoils applicable to large high-speed aircraft, the effects of roughness on three 22-percent-thick airfoils were investigated. The tests were made over a range of Reynolds number from about 6 to 26 x 10(exp 6) for the airfoils smooth and with roughness strips applied to the surfaces. The results indicated that for the roughened models the scale effect was generally favorable" (p. 1).
Tests were made in the NACA two-dimensional low turbulence pressure tunnel of a highly cambered low-drag airfoil (NACA 65,3-618) with a plain flap designed for lift control. The results indicate that such a combination offers attractive possibilities for obtaining low profile-drag coefficients over a wide range of lift coefficients without large reductions of critical speed.
"The effect of two-dimensional bumps and surface waviness on the pressure distribution over airfoils is considered. It is shown that the results of the analysis may be useful in evaluating the effects of accidental or intended surface distortions on the drag and critical Mach number of airfoils" (p. 1).
Report discusses the results of an experimental investigation of two low-drag wing-nacelle units suitable for use with pusher propellers. The benefits of adding a nacelle to the wing are detailed.
The development of the laminar boundary layer in a compressible fluid is considered. Formulas are given for determining the boundary-layer thickness and the ratio of the boundary-layer Reynolds number to the body Reynolds number for airfoils and bodies of revolution. It is shown that the effect of compressibility will profoundly alter the Reynolds number corresponding to the upper limit of the range of the low-drag coefficients.
From Summary: "The results of an experimental investigation of several low-drag wing-nacelle combinations, incorporating internal air-flow systems, are presented. The external-drag increments due to these nacelles are between one-half and two-thirds of those of conventional nacelle forms. This improvement is accomplished with only minor effects on the lift and moment characteristics of the wing. The procedure employed to determine the external shape of such low-drag nacelles is considered in detail. The design of an efficient internal-flow system with or without a blower or throttle, presents no serious problems. The energy losses in the expansion before the engine and the contraction thereafter can be kept small. It is believed that these nacelles have a wide application in housing engine pusher-propeller units and, with some alteration, jet-propulsion devices. It is probable that the low external drags may not be realized if such nacelles are used with a tractor propeller because of the high level of turbulence in the propeller slipstream."
Report presenting tests made on an NACA 23012 airfoil fitted with a 20-percent-chord, true-contour aileron with 35-percent-chord, extreme blunt-nose balance. The primary purpose of the investigation was to determine the variation of the aerodynamic characteristics of this type of aileron with airspeed; the effect of variations of gap width and balance-nose radii was also investigated. Results regarding hinge moments, lift, and pitching-moment coefficients are provided.
From Summary: "An analysis of the nose-inlet shapes developed in previous investigations to represent the optimum from the standpoint of critical speed has shown that marked similarity exists between the nondimensional profiles of inlets which have widely different proportions and critical speeds. With the nondimensional similarity of such profiles established, the large differences in the critical speeds of these nose inlets must be a function of their proportions. An investigation was undertaken in the Langley 8-foot high-speed tunnel to establish the effects of nose-inlet proportions on critical Mach number and to develop a rational method for the design of high-critical-speed nose inlets to meet desired requirements."
Report presenting charts showing the rotor profile drag-lift ratio for a helicopter rotor operating in forward flight and having hinged rectangular untwisted blades. The charts are given for a range of power input covering glides, level flight, and moderate rates of climb. A drag curve was used for preparing the charts, and the curve is compared with experimental curves for typical airfoils.
Report presenting data that show the knock-limited performance of methyl tert-butyl ether obtained from tests made in a 17.6-cubic-inch-displacement engine under supercharged conditions. Tests for temperature sensitivity, speed sensitivity, and lead susceptibility were made on a blend of 20 percent methyl tert-butyl ether and 80 percent S-2 reference fuel.
Report presenting an investigation of the suitability of methyl tert-butyl ether as a component of aviation fuel from considerations of knock-limited performance tests and laboratory inspection tests. Data were obtained from testing on the 17.6 engine under supercharged conditions with fuel blends containing 10 and 20 percent methyl tert-butyl ether. Results regarding small-scale-engine data, full-scale-engine data, and inspection data are provided.
Report presenting data obtained when a float with both horizontal and vertical velocity contact on a water surface. The report is confined to a presentation of the relationship between resultant velocity and impact normal acceleration for various float weights when all other parameters are constant.
Report presenting determinations of boundary-layer transition on the NACA 0012 and 23012 airfoils in the high-speed wind tunnel over a range of Reynolds numbers. For all of the lift coefficients that testing occurred at, transition occurred in the region of estimated laminar separation at low Reynolds numbers and approached the point of minimum static pressure as a forward limit at high Reynolds numbers.
Report presenting testing in the high-speed wind tunnel to determine the drag characteristics of several types of radial-engine nacelle on a low-drag airfoil. The drag coefficients of nacelles incorporating cowling-nose shapes shown by previous tests to be efficient and afterbodies of adequate length were about the same magnitude as commonly obtained for comparable installations on conventional wings. Results regarding the reduction of data, effect of nacelles on lift, and pressures at wing-nacelle juncture are provided.
Report presenting force tests of the NACA 23012 and 23012-64 airfoils of 24-inch chord in the high-speed wind tunnel at a range of Mach numbers. The results show the variation with mach number of lift, drag, and pitching-moment coefficients at a range of angles of attack.
Report presenting testing in the 8-foot high-speed wind tunnel to determine the effect on external drag and pressure distribution of air inlet openings on the stagnation point of a streamline body. The results showed that external drag of the body with suitably designed nose-inlet and tail-outlet openings over a wide range of rates of internal air flow was no higher than the drag of the streamline body. Specific results for the streamline body, nose-inlet openings, outlet openings, and inlet-outlet combinations are provided.
Test of a ducted body with Internal flow were made in the 8-foot high-speed wind tunnel for the purpose of studying the effects on external drag and an critical speed of the addition of efficient inlet and outlet openings to a basic streamline shape. Drag tests of a 13.6- inch-diameter streamline body of fineness ratio 6.14 were made at Mach numbers ranging from 0.20 to 0.75. The model was centrally mounted on a 9-percent-thick airfoil and was designed to have an efficient airfoil-body juncture and a high critical speed.
Report presenting simple curves by which the basic pressure-drop characteristics of unheated tubular radiators can be corrected to operating conditions in which the radiator is heated and in which the Mach number of the tube flow is of appreciable magnitude. The only data required for the use of the curves are the radiator dimensions, the rate of heat input, the pressure and temperature ahead of the radiator, and the rate of mass flow of air through the radiator.
Report presenting tests conducted in the 8-foot high-speed wind tunnel of a scale model pursuit-type fuselage with practicable internal duct arrangement designed to meet all of the air requirements of a 1000-horsepower radial engine submerged at the maximum section. The results showed that the required internal flow can be obtained with negligible ducting losses provided that basic principles are observed in designing the air passages.
Report presenting a flight investigation made to determine the effectiveness of dive-recovery flaps installed on the XP-51 airplane as a safety device for recovery from contemplated terminal-velocity dives. The flap installation is described and results are presented of measurements obtained during stick-free pull-ups and pull-outs made by deflecting the dive-recovery flaps to two selected values of flap angle .
Report presenting investigations to determine the knock-limited performance of blends of 90 percent by volume AN-F-28, Amendment-2 fuel, and 10 percent by volume of the following fuels: tert-amyl alcohol, 2,6-dimethyl-1, 4-dioxane, methyl tert-butyl ether, methyl tert-butyl ketone, methyl isobutyl ketone, mesityl oxide, acetone, and diisopropyl ketone.
Report presenting the effect of internal cooling on the knock-limited performance of AN-F-28 fuel in a CFR engine with the following internal coolants: water, methyl alcohol-water mixture, ammonia-methyl alcohol-water mixture, monomethyllamine-water mixture, dimethylamine-water mixture, and trimethylamine-water mixture.
Report presenting an investigation to determine the knock-limited performance of AN-F-28, Amendment-2, fuel in a DCFR engine when water solutions of the following aliphatic amines were added as internal coolants: monomethylamine, dimethylamine, ethylendiamine, diethylamine, triethylamine, and butylamine. Results regarding the mean effective pressure, indicated specific fuel competition, indicated specific liquid consumption, and knock-limited inlet-air pressure plotted against fuel-air ratio are presented for each fuel and amine combination.
Report presenting a bibliography and review of information related to the hydrodynamics of seaplanes. Characteristics of conventional hulls and floats are discussed to show the effects upon performance of changes in design parameters like dead rise, depth of step, and angle of afterbody keel. Other topics include floats, lateral stabilizers, aerodynamic and propulsive considerations, unconventional configurations, hydrofoils, and piloting and handling.
Tests were conducted on hydrofoil assemblies approximating an arrangement for use under seaplanes or surface boats. A series of hydrofoils, each supported by two struts, was towed at various depths ranging from partial submersions to a depth of 5-chord lengths. At depths greater than 4 or 5 chords, the influence of the surface of the water is small; hydrofoils operating at low speed will have characteristics similar to those of airfoils of the same section.
Report presenting a generalized drag curve providing an estimate for the drag rise due to compressibility as obtained from an analysis of wind-tunnel data of several airfoils, fuselages, nacelles, and windshields at speeds up to and above the wing critical speed. Results regarding drag characteristics and terminal-velocity calculation are provided.
Report presenting an investigation in two-dimensional flow to determine the effect of leakage past the aileron nose on the aerodynamic characteristics of ailerons. The effects of amount and type of leakage, aileron contour, and Mach and Reynolds number are investigated.
Report presenting an investigation of ailerons with a beveled trialing edge and a blunt-nose overhang of 35 percent aileron chord on an NACA 66(215)-26 airfoil in two-dimensional flow. Five configurations were tested with various modifications of the aileron nose and adjacent airfoil contour to determine the effect of modifications on lift and aileron hinge-moment characteristics.
Report presenting a study of nitrided-steel piston rings in nitrided-steel cylinder barrels, which showed material of high reflectivity on their running faces. The structure of the material could not be resolved at a magnification of 1500 diameters. Results regarding the occurrence of coating, thickness of coating, height of coating above the nominal surface, chemical characteristics, physical characteristics, metallurgical change, and additional tests are provided.
From Summary: "Tests were made of an 0.309-chord double-slotted flap on an NACA 65, 3-118, a equals 1.0 airfoil section to determine drag, lift, and pitching-moment characteristics for a range of flap deflections. Results indicate that combination of a low-drag airfoil and a double-slotted flap, of which the two parts moved as a single unit, gave higher maximum lift coefficients than have been obtained with plain, split, or slotted flaps on low-drag airfoils. Pitching moments were comparable to those obtained with other high-lift devices on conventional airfoils for similar lift coefficients."
Report presenting an investigation to obtain blade design data for high-efficiency axial-flow fans and compressors, which were carried out in a two-dimensional low-speed cascade tunnel. The effects of camber, solidity, and stagger on blade turning angle and the shape of pressure distributions were determined for a family of five low-drag airfoils.
Report presenting a tabular method for determining the span load distribution at high Mach numbers by utilizing high-speed airfoil section data. This method, which is also called the generalized method, is an easily applied process of successive approximations by which a general application of the lifting-line theory may be used to determine the span load distribution for wings composed of sections with arbitrary lift curves. An example is provided to show how the method is used.
From Summary: "A design chart in coefficient form is presented from which a radiator can be chosen with any desired characteristics, whether for minimum power, particular dimensions, or pressure drop for cooling. The chart is a convenient tool for selecting a practicable radiator for any given set of operating conditions. Because the flow is turbulent in the tubes, the chart is for turbulent-flow conditions."
"Following a brief history of the NACA investigation of jet-propulsion, a discussion is given of the general investigation and analyses leading to the construction of the jet-propulsion ground-test mock-up. The results of burning experiments and of test measurements designed to allow quantitative flight-performance predictions of the system are presented and correlated with calculations. These calculations are then used to determine the performance of the system on the ground and in the air at various speeds and altitudes under various burning conditions. The application of the system to an experimental airplane is described and some performance predictions for this airplane are made" (p. 1).
From Summary: "An investigation has been conducted to determine the possible extent of effects of wind-tunnel constriction at high speeds for airfoils of various thickness-to-chord ratios at or near zero lift. The results indicate that a limiting test Mach number exists which is principally a function of the ratio of model thickness to tunnel height. At high Mach numbers serious constriction effects occur; these effects are of such a nature that the standard calibration methods given speeds much lower than the actual test speeds."
Report presenting an investigation of the effects on stability and control of a pusher propeller behind conventional horizontal and vertical tail surfaces in the free-flight tunnel by tests of a scale model of a submerged-engine pusher airplane. The investigation consisted of flight and balance tests at windmilling and high-power conditions with a partial-span Zap extensible flap extended and retracted. Results regarding the longitudinal stability, longitudinal control, stalling characteristics, lateral stability, and lateral control are provided.
Force and flight tests were performance on an all-wing model with windmilling propellers. Tests were conducted with deflected and retracted flaps, with and without auxiliary vertical tail surfaces, and with different centers of gravity and trim coefficients. Results indicate serious reduction of stick-fixed longitudinal stability because of wing-tip stalling at high lift coefficient. Directional stability without vertical tail is undesirably low. Low effective dihedral should be maintained. Elevator and rudder control system is satisfactory.
Report presenting an extension of previously reported data on the variation of maximum lift coefficient with Mach number, camber, and thickness ratio. The data were obtained from pressure-distribution tests in the 8-foot high-speed tunnel of six propeller airfoils of 1-foot chord.
Report presenting pressure distribution tests of six NACA 16-series propeller sections with 1-foot chords in the 8-foot high-speed tunnel to determine the compressibility effects on peak section pitching-moment coefficients. Data is presented as curves of peak section pitching-moment coefficient against Mach number, thickness ratio, and camber. The peak pitching-moment coefficients were found to occur in the regions of positive and negative stall.
Report presenting results of flight tests to determine the turning performance of a Navy F2A-3 airplane over a range of speeds for three flap deflections at two altitudes. The results are correlated with an analytical study of turning performance in which the effect of thrust on maximum lift coefficient was considered.
The work done under this contract falls essentially into two parts: the first part was the design and construction of the equipment and the running of preliminary tests on the 3-inch jet, carried out by Mr. Carl Thiele in 1940; the second part consisting in the measurement in the 1-inch jet flow in an axially symmetrical heated jet of air.
Report presenting an investigation made of the flow downstream from a two-dimensional grid, formed of parallel rods. The two-dimensional character of the flow was insured by end plates normal to the rods and covering the entire flow field. The nature of the flow was determined primarily by means of total-head measurements.
Report presenting an investigation of the flow downstream from a two-dimensional grid formed of parallel rods. The nature of the flow was determined primarily by means of total-head measurements. Preliminary tests were made in both the closed-duct and open, two-dimensional configurations, but it was found that the same phenomenon occurred in both cases.
An investigation was made of the cooling characteristics of a P and W R-2800 engine with NACA short-nose high inlet-velocity cowling. The internal aerodynamics of the cowling were studied for ranges of propeller-advance ratio and inlet-velocity ratio obtained by deflection of cowling flaps. Tests included variations of engine power, fuel/air ratio and cooling-air pressure drop. Engine cooling data are presented in the form of cooling correlation curves, and an example for calculation of cooling requirements in flight is included.
Report presenting an equation based on simple blade-element theory and the assumption of a fixed wake pattern is derived and fitted to available data to show the first-order relation between the parameters of propeller operation and intensity of wake-excited periodic force acting on the blades of a pusher propeller. The derived equation indicates that the effect of power coefficient on the intensity of the wake-excited periodic force is small. Limited data also indicates that the wake-excited vibratory stress in a propeller increases with the drag of the body producing the wake.
From Introduction: "As a part of the general lateral-control investigation by the NACA, the large amount of two- and three-dimensional data on the rolling effectiveness of ailerons without exposed overhang balance is collected and analyzed in the present paper."
Report presenting an investigation in the 7- by 10-foot wind tunnel of the effects of various modifications to the profile of a 0.20-chord plain sealed aileron and a 0.15-chord plain sealed aileron on an NACA 66,2-216 airfoil. Thickening of the aileron was found to reduce the aileron effectiveness, reduce the slope of the wing section lift curve, and reduce the hinge-moment coefficients. Results regarding the section data, aileron effectiveness, aileron hinge moments, lift, pitching moment, drag, and Reynolds number are provided.
Report presenting an investigation in the 7- by 10-foot wind tunnel of the effects of modifications to the trailing edge of a 0.20-chord plain sealed aileron on an NACA 66,2-216 airfoil. The modifications considered consisted of various amounts of symmetrical thickening and beveling of the aileron trailing edge. Results regarding aileron effectiveness, aileron hinge moments, aileron control forces, lift, pitching moment, drag, and Reynolds number are provided.
Report presenting the calculated performance of four-, six-, and eight-blade single-rotating propellers compared with experimental results for blade angles ranging from 25 to 65 degrees. The data were obtained on propellers mounted in front of a streamline body with a spinner housing the hub.
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