National Advisory Committee for Aeronautics (NACA) - 116 Matching Results

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Progress Summary Number 1: Mechanical Properties of Flush-Riveted Joints Submitted by Five Airplane Manufacturers: Summary presenting information on flush-riveted joints for aircraft construction, including the strength, occurrence of defects, and effect of the angle of rivet head. The current tests covers specimens from 15 manufacturers of which 5 series have been completed and are described in this report.
Calculation of tab characteristics for flight conditions from wind-tunnel data: Report presenting tail-surface characteristics calculated from wind-tunnel data, which have been reported to not correspond with flight-test measurements. The primary problem under consideration is the calculation of the effect of tab deflection on the free-floating angle of the elevator, as in a servocontrol.
XC-35 Gust Research Project Operation in Cumulus Congestus Cloud on July 31, 1941 Maximum Gust Intensities: "On July 31, 1941 a turbulence survey was made with the XC-35 airplane of a large cumulus congestus cloud near Langley Field, Va. This bulletin presents a general description of conditions and the maximum gust intensities recorded during the flight" (p. 1).
The Preparation of 2, 2, 4, 4-Tetramethylpentane: Report presenting seven distinct operations in the preparation of 2,2,4,4-tetramethylpentane, including the preparation of di-isobutylene hydrochloride, preparation of dimethylzinc, reaction of dimethylzinc in dry benzene with di-isobutylene hydrochloride, preliminary distillation of the reaction products, treatment of the first distillate with sodium and alcohol, final distillation after appropriate washing of the products, and recovery of the iodine in the zinc residues of II as methyl iodide.
Application of Balancing Tabs to Ailerons: Analysis was made to determine characteristics required of a balancing-tab system for ailerons in order to reduce aileron stick forces to any desired magnitude. Series of calculations based on section data were made to determine balancing-tab systems of various chord tabs and ailerons that will give, for a particular airplane, zero rate of aileron hinge moment with aileron deflection and yet will produce same maximum rate of roll as a plain unbalanced 15-percent chord aileron of same span. Effects of rolling velocity and of forces in tab link on aileron hinge moments have been included.
The Fatigue Strengths of Some Wrought Aluminum Alloys: Report presenting an exploration of fatigue stresses of some wrought aluminum alloys, including charts that cover different ranges of stress and number of cycles.
Influence of Loading Condition on Piloting Technique for Spin Recovery for Pursuit Airplanes: Bulletin presenting a discussion of information as to the influence on spins and spin recovery of the wing loading and load distribution of present-day pursuit airplanes. The high wing loadings results in high rates of descent and large control forces for recovery.
A Study of the Tightness and Flushness of Machine-Countersunk Rivets for Aircraft: Bulletin presenting the results of an investigation to determine possible improvements in the tightness and the flushness of machine-countersunk rivets. Specimens used in the study were simple lap joints made by different riveting methods. The results indicate that a comparison of the quality of machine-countersunk riveted joints on the basis of maximum load alone is not justified.
Flight investigation of a stall-warning indicator for operation under icing conditions: Report presenting an investigation to determine whether some characteristic of the boundary layer could be used to provide warning of the increase in stalling speed of a wing caused by ice formations on the leading edge. Results were analyzed by referring the total pressures at the rake to the free-stream total pressure, static pressure at the rake, free-stream static pressure, and static pressure from wind-tip swiveling head.
Summary of V-G records taken on transport airplanes from 1932 to 1942: Report presenting an analysis of records of more than 134,000 flying hours, which have been received and evaluated in order to bring the V-G recorder data up to date. The analysis of the records is contained in the report. Results indicate that the maximum effective gust velocities for both the land transport airplanes and the flying boats have approached values of 40 feet per second.
Tests of a Stressed-Carrying Door in Shear: Bulletin presenting testing of a monocoque box with a stress-carrying door made and tested in torsion. The results indicate that if a stress-carrying door and its frame are made sufficiently heavy, the torsional stiffness of the box with the door can be made greater than the torsional stiffness of the box without the cut-out" (p. 1).
Effect of Normal Pressure on the Critical Compressive Stress of Curved Sheet: Results are presented of tests of two specimens tested to study the effect of normal pressure on the critical compressive stress for thin curved sheets. These specimens are designated by their respective rib spacings of 10 inches and 30 inches. The relationship between compressive stress and normal pressure at which buckles disappeared is independent of whether the buckles were made to disappear by increase of normal pressure or decrease of compressive stress. (author).
Comparison of tightness of 78 degrees machine-countersunk rivets driven in holes prepared with 78 degrees and 82 degrees countersinking tools: Report presenting an investigation to determine whether the use of a 78 degree countersinking tool instead of a 82 degree countersinking tool for riveting would substantially alter the conclusion reached in a previous paper regarding the placement of rivets for maximum strength.
A Description of the Ju 88 Airplane Anti-Icing Equipment: Bulletin presenting an examination of a part of the anti-icing equipment for a Ju 88 airplane, including exhaust-air heat exchangers, control valves, air duct system, and air-heated wing panels. Testing was performed on the components and indicated that the thermal ice-prevention equipment can maintain the outer-wing panel free from ice.
Tests of a Stress-Carrying Door in Compression: Bulletin presenting the results of bending tests on a monocoque box with the door on the compression side. The results indicate that the effectiveness of a stress-carrying door depends on the intended function of the door.
Effect of Countersunk Depth on the Tightness of Two Types of Machine-Countersunk Rivet: Bulletin presenting an investigation conducted to determine the effect of countersunk depth on the tightness of two types of machine-countersunk flush rivet. The specimens tested in the study were simple lap joints made by two different riveting methods. The results indicated that roundheaded rivets inserted from the back of the joint with the countersunk heads formed int he driving of the rivets produce tighter joints over a large range of depths than ordinary flush rivets.
Adjustment of Stick Force by a Nonlinear Aileron-Stick Linkage: Report presenting an application of the principle of aileron-stick forces and mechanical advantage to an aileron installation in which the stick forces are small over the low-deflection range and excessively large at full deflection.
Test Data on the Shear Strength of Machine Countersunk-Riveted Joints Assembled by an NACA Flush-Riveting Procedure: Bulletin presenting load-displacement curves for use in establishing allowable-load values for riveted joints assembled by an NACA flush-riveting procedure. Comparative data are also given to show the effect of variations in the procedure on the yield and maximum shear loads for the rivets.
Effect of Normal Pressure on the Critical Shear Stress of Curved Sheet: "In order to determine the critical stresses caused by an outward acting pressure on the upper surface of a wing due to the difference in internal and external pressures, torsional tests were made on two curved-sheet specimens subjected to an outward acting normal pressure. Results show that an outward acting normal pressure appreciable raises the critical shear stress for an unstiffened curved sheet; the absolute increase in critical shear stress is slightly greater for a 30 in. rib spacing than for a 10 in. rib spacing" (p. 1).
Hydrodynamic-stability tests of a model of a flying boat and of a planing surface having a small downward projection (hook) on the planing bottom near the step: Report presenting stability testing of two dynamic models in tank no. 1 in order to investigate the effects of adding a small projection, or hook, on the planing bottom of the forebody near the step of a seaplane. Tests with two different projections had a rather large effect on all of the trim limits and the landing stability.
The belt method for measuring pressure distribution: "The measurement of pressure distribution may be accomplished rapidly for any number of locations deemed necessary in model or full-scale investigations by use of the 'belt' method. Reasonable accuracy may be obtained by careful use of this method" (p. 1).
A simplified chart for determining Mach number and true airspeed from airspeed-indicator readings: "The determination of flight Mach number from measurements of indicated airspeed and pressure altitude is shown to be relatively simple and leads to direct and accurate computation of true airspeed. A simplified chart is presented for determining flight Mach number and true airspeed for a range of values of indicated airspeed, pressure altitude, and air temperature. A table of standard atmospheric values is included" (p. 1).
XC-35 gust research project: Preliminary analysis of the lateral distribution of gust velocity along the span of an airplane: Report presenting measurements of the lateral distribution of effective gust velocity along the span of the XC-35 airplane in a variety of weather conditions. Six standard shapes were determined from the distributions: triangular, rectangular, first trapezoidal, second trapezoidal, unsymmetrical, and double triangular.
Effect of Varying Percentages of Exhaust Gas on Engine Performance: "These tests were run to determine the effect that mixing engine exhaust gas with engine intake air has on fuel knock limit, specific fuel consumption, and air consumption." Information about the effect on pressure, air consumption, and fuel consumption is detailed.
Flight Tests of a Glider Model Towed by Twin Parallel Towlines: "The stability characteristics of a glider towed by twin parallel towlines have been studied in the NACA free-flight tunnel. A preliminary theoretical analysis of the stability of a glider restrained from yawing was followed by an experimental investigation of the stability of a model towed from fixed tunnel points in such a way as to simulate tow in level flight. The results of the tests confirm the theoretical analysis and indicate that a pilotless, stable, towed-glider system is possible when twin parallel towcables are used" (p. 1).
A Study of the Effects of Radii of Gyration and Altitude on Aileron Effectiveness at High Speed: "The variation in the necessary aileron control and in the time required to bank to 45 degrees and 90 degrees with altitude and radii of gyration for a typical fighter or a pursuit airplane have been computed and are presented herein." The lateral motions and impact pressure for several conditions of flight are provided. The report concludes that "the aileron system...should be designed for rolling-moment requirements at high altitude and the hinge-moment limitations at low altitude".
Effect of Powered Propellers on the Aerodynamic Characteristics and the Porpoising Stability of a Dynamic Model of a Long-Range Flying Boat: Report discusses the results of two tests: "1) aerodynamic tests to determine the effect of the slipstream and thrust from the powered propellers on the lift and trimming-moment characteristics, and 2) hydrodynamic tests to determine the effect of the powered propellers on the range of stable locations of the center of gravity (from Introduction)." Large differences in the stable range between half-thrust and full-thrust conditions were observed. Three effects of power were also involved in the location of the stable range of the center of gravity.
Emergency Measures for Increasing the Range of Fighter Airplanes: "An analysis was made to show the relative effectiveness of streamline external fuel tanks, a fuel tank in the form of a wing mounted in a biplane position, and auxiliary wing panels attached at the wing tips to increase the span as temporary means for increasing the range of a fighter-type airplane. Figures and charts for the various devices considered show the results of calculations of range, duration of flight, and take-off distance for both land-base and carrier operation. The results indicated that the wing-tip extensions were the most promising of the devices considered" (p. 1).
The Longitudinal Shear Strength Required in Double-Angle Columns of 24S-T Aluminum Alloy: "Tests were made of riveted double-angle columns to determine the total rivet strength that is required to make these built-up columns develop the strength predicted by the standard column formulas. Results of the tests led to the conclusion that the required rivet strength may be calculated by the beam method of design" (p. 1).
Shear Tests on DuPont Explosive Rivets With the Countersunk Head Milled Flush After Expansion: Report discusses the results of shear testing in which the heads of Du Pont explosive countersunk rivets were allowed to protrude above the skin surface before expansion and the protruding portions were removed after expansion. As the height of the rivet head above the skin increases, the tightness of the rivet was found to increase. The report concludes that it may be desirable to investigating filling an entire shank with an explosive charge in order to permit greater tolerances in the drilled hole diameter and still have consistently tight rivets.
Resume of Hinge-Moment Data for Unshielded Horn- Balanced Control Surfaces: Report summarizes the available hinge-moment data for unshielded horn-balanced control surfaces. The purpose is to correlate the available data to assist with estimating the balance characteristics for use in the design and alteration of control surfaces with horn balances. Plan forms and variation of incremental hinge-moment-coefficient slopes with balance coefficients are presented.
Test Data on the Shear Strength of Joints Assembled With Round-Head and Brazier-Head Rivets: Report discusses data obtained from testing shear of joints riveted with round-head and brazier-head rivets. The tightness of the rivets is also compared for one value of rivet diameter. The load-displacement curves and comparison of load at various values of permanent displacement are presented for both types of rivets.
Tests of 10-Inch 24S-T Aluminum-Alloy Shear Panels With 1-1/2-Inch Holes: Report discusses the results of testing on "10-inch shear panels of 24S-T aluminum alloy with 1.5 inch holes to determine the stress concentration at static rupture and the deformation characteristics" (from Summary). The strength of the perforated specimens is compared to the solid specimens and the critical stresses are computed. The stress at which permanent set occurs was also measured.
Thermodynamic Design of Double-Panel, Air-Heated Windshields for Ice Prevention: Report details the development of design equations for double-panel, air-heated windshields with ice prevention properties. The application of the equations and suggestions for experimental flight testing are described.
NACA Procedure for Flight Tests of Aileron Characteristics of Airplanes: Report describes the standard procedure that NACA used for evaluating the aileron characteristics of airplanes. The variables measured in the testing are rolling velocity, aileron positions, aileron stick forces or tangential wheel force, indicated airspeed, altitude, free-air temperature, and rudder position. The step-by-step flight procedure is described and information regarding evaluation of the control data and general suggestions is included.
The Effect of Artificial Aging on the Tensile Properties of Alclad 24S-T and 24S-T Aluminum Alloy: "An experimental study was made to determine the effect of artificial aging on the tensile properties of alclad 24S-T and 24S-T aluminum-alloy sheet material. The results of the tests show that certain combinations of aging time and temperature cause a marked increase in the yield strength and a small increase in the ultimate strength; these increases are accompanied by a very large decrease in elongation. A curve is presented that shows the maximum yield strengths that can be obtained by aging this material at various combinations of time and temperature" (p. 1).
An Approximate Method of Shear-Lag Analysis for Beams Loaded at Right Angles to the Plane of Symmetry of the Cross Section: Report discussing strain measurements made on a box beam of triangular cross section and on two beams of D-section under transverse bending. Information about the arrangement of the beams and experimental and calculated stresses for different boxes.
Critical Compressive Stress for Curved Sheet Supported Along All Edges and Elastically Restrained Against Rotation Along the Unloaded Edges: "A formula is given for the critical compressive stress for slightly curved sheet with equal elastic restraints against rotation along the unloaded edges. The theory of small deflections is used and the formula reduces to that given by Timoshenko for the case of simply-supported edges. For larger curvatures, a modification of Redshaw's formula to include the effect of edge restraint is suggested" (p. 1).
Notes on the Skipping of Seaplanes: Report discusses five tests related to seaplane skipping and attempts to prevent it by changing the depths of step to avoid large suction force on the afterbody generated by the flow behind a shallow step. Flying boats of various sizes and weights were tested during landing and several degrees of trim were tested for boats that had a particularly shallow step. Design suggestions for future flying boats are also included.
Some Notes on the Determination of the Stick-Fixed Neutral Point From Wind-Tunnel Data: "Two methods are presented for determining the horizontal location of the stick-fixed neutral point from wind-tunnel data. One method involves the solution of a mathematical equation; whereas the other method is a graphical solution for the same mathematical equation. The combined horizontal and vertical variation of the neutral point completely describes the stick-fixed longitudinal stability of airplanes that have large allowable center-of-gravity shifts" (p. 1).
Use of Stagnation Temperature in Calculating Rate of Heat Transfer in Aircraft Heat Exchangers: "Theoretical and experimental investigations of the effect of frictional heat on the rate of heat transmission at high fluid velocities are briefly reviewed. On the basis of these investigations, calculations are made which show that the use of the stagnation temperature of the cooling air as the effective temperature for heat transfer in an aircraft heat exchanger is sufficiently accurate" (p. 1).
Preliminary Tests to Determine the Dynamic Stability Characteristics of Various Hydrofoil Systems for Seaplanes and Surface Boats: Report discusses the results of testing on the dynamic stability characteristics of various hydrofoil systems for seaplanes, including a flat-hydrofoil tandem system, a 20 degree V-hydrofoil tandem system, a curved-hydrofoil tandem system, a flat-hydrofoil ladder system, a Guidoni S.V.A.-type hydrofoil on a streamline spindle, and several self-propelled models, including the Tietjens hydrofoil system. The instability and spray were compared for the different systems.
Wind-Tunnel Tests of a Piston-Type Control Booster on an Airfoil and Aileron Model: "Measurements of control moments were made in the NACA stability tunnel to determine the operational characteristics of a piston-type control booster on an aileron. The booster was so constructed and installed that pressures picked up from the air stream below the wing acted on a pair of pistons. The data are presented in the form of curves of pressure coefficients acting on the pistons, hinge-moment coefficients, and booster coefficients plotted against aileron deflection" (p. 1).
A Preliminary Study of Machine-Countersunk Flush Rivets Subjected to a Combined Static and Alternating Shear Load: Report discusses the results of an investigation to study the effect of the height of a rivet head on the number of cycles required to cause failure of a machine-countersunk flush-riveted joint under a combined static and alternating shear load. A tight joint and a loose joint were tested and the number of cycles to failure and location of fatigue failure were compared.
Proposal for a Propeller Side-Force Factor: Report discusses a proposal for propeller manufacturers to consider the side-force factor with the activity factor as a fundamental parameter for all blade designs and for the side-force factor to be included in all reports of powered models in wind tunnels. The proposal includes a method for calculating the side-force factor and how it can be used in propeller development. It is shown to be a good index of the relative effectiveness per blade of a yawed propeller in developing side force.
Effect of Inlet-Air Temperature and Cylinder Displacement on Charge Temperature of Internal Combustion Engines: Report discussing the effect of inlet-air temperature and cylinder displacement on the charge temperature of an internal-combustion engine at the end of the induction stroke. The experiment to test various types of cylinders and their results on the air temperature and pressure is described.
Use of Internal Coolant as a Means of Permitting Increase in Engine Take-Off Power: Engine tests, together with estimates made at Langley Memorial Aeronautical Laboratory, indicate that a 25-percent increase in take-off power can be obtained with present-day aircraft engines without increasing either the knock limit of the fuel or the external cooling requirements of the engine. This increase in power with present fuels and present external cooling is made possible through the use of an internal coolant inducted through the inlet manifold. Estimates on aircraft indicate that this 25-percent increase in power will permit an approximate usable increase of 8.5 percent in the take-off load of existing military airplanes. This increase in load is equivalent to an increase in the weight of gasoline normally carried of between 30 and 65 percent.
Comparative Tests of the Strength and Tightness of Commercial Flush Rivets of One Type and NACA Flush Rivets in Machine-Countersunk and Counterpunched Joints: Report discusses an investigation that was conducted to compare the strength and tightness of machine-countersunk flush-riveted joints assembled with NACA flush rivets and a type of commercial flush rivet. A comparison was also generated between the strength and tightness of counterpunched flush-riveted joints assembled with the same types of rivet. NACA's flush-riveted joints tended to be stronger and tighter than the commercial joints.
Landing Characteristics of a Model of a Flying Boat With the Depth of Step Reduced to Zero by Means of a Retractable Planing Flap: "A model of a flying boat was tested to determine the landing characteristics when the depth of the step was reduced to zero by means of a retractable planing flap on the forebody" (p. 4). The results of stability and resistance testing are presented.
The Landing Stability of a Powered Dynamic Model of a Flying Boat With a 30 Degree V-Step and With Two Depths of Transverse Step: Report discusses tests conducted using a model of a four-engine long-range flying boat with a 30 degree V-step and two different transverse steps of comparable positions and depths. The limits of stability, landing speed, and landing characteristics of the different models are presented.

National Advisory Committee for Aeronautics (NACA) - 116 Matching Results

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