27 Matching Results

Search Results

Advanced search parameters have been applied.

Relative Efficiencies and Design Charts for Various Engine-Propeller Combinations, Special Report

Description: "The relative efficiencies of various engine-propeller combinations were the subject of a study that covered the important flight conditions, particularly the take-off. Design charts that graphically correlate the various propeller parameters were prepared to facilitate the solution of problems and also to clarify the conception of the relationships of the various engine-propeller design factors. It is shown that, among the many methods for improving the take-off thrust, the use of high-pitch, large-diameter controllable propellers turning at low rotational speeds is probably the most generally promising" (p. 1).
Date: September 1936
Creator: Biermann, David
Partner: UNT Libraries Government Documents Department

The aerodynamic characteristics of four full-scale propellers having different plan forms

Description: From Introduction: "Its main purpose is to present propeller data for four full-scale propellers of Navy design, three of which have somewhat unusual plan forms and the other one has a normal (usual present-day type) plan form. These data may give some clue as to what may be expected from fundamental changes in blade plan form."
Date: 1938~
Creator: Hartman, Edwin P. & Biermann, David
Partner: UNT Libraries Government Documents Department

The aerodynamic characteristics of six full-scale propellers having different airfoil sections

Description: From Summary: "Wind-tunnel tests are reported of six 3-blade 10-foot propellers operated in front of a liquid-cooled engine nacelle. The propellers were identical except for blade airfoil sections, which were: Clark y, R.A.F. 6, NACA 4400, NACA 2400-34, NACA 2rsub200, and NACA 6400. The range of blade angles investigated extended for 15 degrees to 40 degrees for all propellers except the Clark y, for which it extended to 45 degrees. The results showed that the range in maximum efficiency between the highest and lowest values was about 3 percent. The highest efficiencies were for the low-camber sections."
Date: 1939
Creator: Biermann, David & Hartman, Edwin P.
Partner: UNT Libraries Government Documents Department

Propeller charts for the determination of the rotational speed for the maximum ratio of the propulsive efficiency to the specific fuel consumption

Description: A set of propeller operating efficiency charts, based on a coefficient from which the propeller rotational speed has been eliminated, is presented. These charts were prepared with data obtained from tests of full-size metal propellers in the NACA propeller-research tunnel. Working charts for nine propeller-body combinations are presented, including results from tests of dual-rotating propellers. These charts are to be used in the calculation of the range and the endurance of airplanes equipped with constant-speed propellers in which, for given flight conditions, it is desired to determine the propeller revolution speed that gives the maximum ratio of the propulsive efficiency to the specific fuel consumption. The coefficient on which the charts are based may be written in the form of a thrust coefficient or a thrust-power coefficient. A method of using the charts is outlined and sample computations for a typical airplane are included.
Date: December 11, 1940
Creator: Biermann, David & Conway, Robert N.
Partner: UNT Libraries Government Documents Department

The Selection of Propellers for High Thrust at Low Airspeed

Description: Problem of improving thrust at low speeds is primarily one of reducing angle of attack of operation of sections to improve L/D or reducing blade helix angle. An analysis, based on recent propeller data, is presented for determining improvements in thrust or efficiency which could be obtained by increased number of blades, increased blade width, increased diameter, dual rotation, and two-speed gearing. All methods were found very effective, particularly two-speed gearing.
Date: October 1941
Creator: Biermann, David & Conway, Robert N.
Partner: UNT Libraries Government Documents Department

Tests of five full-scale propellers in the presence of a radial and a liquid-cooled engine nacelle, including tests of two spinners

Description: Wind-tunnel tests are reported of five 3-blade 10-foot propellers operating in front of a radial and a liquid-cooled engine nacelle. The range of blade angles investigated extended from 15 degrees to 45 degrees. Two spinners were tested in conjunction with the liquid-cooled engine nacelle. Comparisons are made between propellers having different blade-shank shapes, blades of different thickness, and different airfoil sections. The results show that propellers operating in front of the liquid-cooled engine nacelle had higher take-off efficiencies than when operating in front of the radial engine nacelle; the peak efficiency was higher only when spinners were employed. One spinner increased the propulsive efficiency of the liquid-cooled unit 6 percent for the highest blade-angle setting investigated and less for lower blade angles. The propeller having airfoil sections extending into the hub was superior to one having round blade shanks. The thick propeller having a Clark y section had a higher take-off efficiency than the thinner one, but its maximum efficiency was possibly lower. Of the three blade sections tested, Clark y, R.A.F. 6, and NACA 2400-34, the Clark y was superior for the high-speed condition, but the R.A.F. 6 excelled for the take-off condition.
Date: 1938
Creator: Biermann, David & Hartman, Edwin P.
Partner: UNT Libraries Government Documents Department

Wind-tunnel investigation of rectangular air-duct entrances in the leading edge of an NACA 23018 wing, special report

Description: A preliminary investigation of a number of duct entrances of rectangular shape installed in the leading edge of a wing was conducted in the NACA 20-foot tunnel to determine the external drag, the available pressure, the critical Mach numbers, and the effect on the maximum lift.
Date: September 1940
Creator: Biermann, David & McLellan, Charles H.
Partner: UNT Libraries Government Documents Department

The Torsional and Bending Deflection of Full-Scale Duralumin Propeller Blades under Normal Operating Conditions, Special Report

Description: The torsional deflection of the blades of three full-scale duralumin propellers operating under various loading conditions was measured by a light-beam method. Angular bending deflections were also obtained as an incidental part of the study. The deflection measurements showed that the usual present-day type of propeller blades twisted but a negligible amount under ordinary flight conditions. A maximum deflection of about 1/10th of a degree was found at V/nD of 0.3 and a smaller deflection at higher values of V/nD for the station at 0.70 radius. These deflections are much smaller than would be expected from earlier tests, but the light-beam method is considered to be much more accurate than the direct-reading transit method used in the previous tests.
Date: March 1938
Creator: Hartman, Edwin P. & Biermann, David
Partner: UNT Libraries Government Documents Department

The drag of airplane wheels, wheel fairings, and landing gears - 3

Description: The tests reported in this report conclude the investigation of landing-gear drag that has been carried out in the NACA 20-foot wind tunnel. They supplement earlier tests (reported in Technical Report No. 485) made with full-scale dummy wheels, wheel fairings, and landing gears intended for airplanes of 3,000 pounds gross weight and include tests of tail wheels and tail skids.
Date: November 21, 1934
Creator: Herrnstein, William H., Jr. & Biermann, David
Partner: UNT Libraries Government Documents Department

The drag of airplane wheels, wheel fairings, and landing gears 2: nonretractable and partly retractable landing gears

Description: This is the second report giving the results obtained in the NACA 20-foot wind tunnel on the drag due to landing gears. The present report gives the results of tests of nonretractable and partly retractable landing gears intended for heavier low-wing monoplanes of the transport and bomber type.
Date: June 21, 1934
Creator: Biermann, David & Herrnstein, William H., Jr.
Partner: UNT Libraries Government Documents Department

The interference between struts in various combinations

Description: This report presents the results of wind tunnel tests made to determine the interference drag arising from various arrangements of streamline struts and round struts, or cylinders. Determinations were made of the interference drag of struts spaced side by side, struts in tandem, tandem struts encased in a single fairing, a strut intersecting a plane, and struts intersecting to form a v. Three sizes of struts were used for most of the tests. These tests show that the interference drag arising from struts in close proximity may be of considerable magnitude, in some instances amounting to more than the drag of the struts themselves.
Date: June 5, 1933
Creator: Biermann, David & Herrnstein, William H., Jr.
Partner: UNT Libraries Government Documents Department

Tests of two full-scale propellers with different pitch distributions, at blade angles up to 60 degrees

Description: Two 3-blade 10-foot propellers were operated in front of a liquid-cooled engine nacelle. The propellers differed only in pitch distribution; one had normal distribution (nearly constant pitch for a blade angle of 15 degrees at 0.75 radius), and the other had the pitch of the tip sections decreased with respect to that for the shank sections (blade angle of 35 degrees for nearly constant pitch distribution). Propeller blade angles at 0.75r from 15 degrees to sixty degrees, corresponding to design speeds up to 500 miles per hour, were investigated. Propeller blade angles at 0.75r from 15 degrees to 60 degrees, corresponding to design speeds up to 500 miles per hour, were investigated. The results indicated that the propulsive efficiency at a blade angle of 60 degrees was about 9 percent less than the maximum value of 86 percent, which occurred at blade angle of about 30 degrees. The efficiency at a blade angle of 60 degrees was increased about 7 percent by correcting for the effect of a spinner and, at a blade angle of 30 degrees about 3 percent. The peak efficiencies for the propeller having the washed-out pitch distribution were slightly less than for the normal propeller but the take-off efficiency was generally higher.
Date: 1939
Creator: Biermann, David & Hartman, Edwin P.
Partner: UNT Libraries Government Documents Department

The Torsional and Bending Deflection of Full-Scale Aluminum-Alloy Propeller Blades under Normal Operating Conditions

Description: The torsional deflection of the blades of three full-scale aluminum-alloy propellers operating under various loading conditions was measured by a light-beam method. Angular bending deflections were also obtained as an incidental part of the study. The deflection measurements showed that the usual present-day type of propeller blades twisted but a negligible amount under ordinary flight conditions. A maximum deflection of about 1/10 degree was found at a v/nd of 0.3 and a smaller deflection at higher values of v/nd for the station at 0.70 radius. These deflections are much smaller than would be expected from earlier tests, but the light-beam method is considered to be much more accurate than the direct-reading-transit method used in the previous test.
Date: 1938
Creator: Hartman, Edwin P. & Biermann, David
Partner: UNT Libraries Government Documents Department

Wind-Tunnel Tests of Eight-Blade Single and Dual-Rotating Propellers in the Tractor Position

Description: Tests of 10-ft. diameter, eight-blade, single - and dual - rotating propellers were conducted in 20-ft propeller research tunnel. Propellers were mounted at front end of a streamline body in spinners that covered hubs and parts of shanks. Effect of a symmetrical wing mounted in slipstream was investigated. Blade-angle settings ranged from 20 Degrees to 65 Degrees. Results indicated that dual rotation resulted in gains of from 1 to 8 percent in efficiency over single rotation for eight-blade propellers, but presence of a wing reduced gain about one-half. Greater power absorption caused by dual rotation over flight range and higher efficiency or thrust for range of take-off and climb was indicated.
Date: November 1941
Creator: Biermann, David & Gray, W. H.
Partner: UNT Libraries Government Documents Department

Wind-tunnel tests of four- and six-blade single- and dual-rotating tractor propellers

Description: Test of 10-foot diameter, four and six blade single-rotating and dual-rotating propellers were conducted in the NACA propeller-research tunnel. The propellers were mounted at the front end of a streamline body incorporating spinners to house the hub portions. The effect of a symmetrical wing mounted in the slipstream ranged from 20 degrees to 65 degrees setting corresponds to airplane speeds greater than 500 miles per hour. The results indicate that dual-rotating propellers were from 0 to 6 percent more efficient than single-rotating ones; but, when the propellers operated in the presence of a wing, the gain was reduced by about one-half. Other advantages of dual-rotating propellers were found to include greater power absorption and greater efficiency at the low V/nD operating range of high-pitch propellers.
Date: 1942
Creator: Biermann, David & Hartman, Edwin P.
Partner: UNT Libraries Government Documents Department

The drag of airplane wheels, wheel fairings, and landing gears - 1

Description: This report presents the results of tests made in the 7-by 10-foot wind tunnel and in the 20-foot tunnel of the National Advisory Committee for Aeronautics to determine the drag of a number of airplane wheels, wheel fairings, and landing gears designed or selected for an airplane of 3,000 pounds gross weight. All tests were made on full-size models; those in the 7-by 10-foot tunnel were made at air speeds up to 80 miles per hour and those in the 20-foot tunnel were made at air speeds up to 100 miles per hour. Although most of the landing-gear tests were made in conjunction with a fuselage and at 0 degree pitch angle, some of the tests were made in conjunction with fuselage plus wings and a radial air-cooled engine and at pitch angles from -5 degrees to 6 degrees to obtain an indication of the general effect of these various items on landing-gear drag.
Date: February 9, 1934
Creator: Herrnstein, William H., Jr. & Biermann, David
Partner: UNT Libraries Government Documents Department

Static Thrust and Power Characteristics of Six Full-Scale Propellers

Description: "Static thrust and power measurements were made of six full-scale propellers. The propellers were mounted in front of a liquid-cooled-engine nacelle and were tested at 15 different blade angles in the range from -7 1/2 degrees to 35 degrees at 0.75r. The test rig was located outdoors and the tests were made under conditions of approximately zero wind velocity" (p. 85).
Date: January 25, 1939
Creator: Hartman, Erwin P. & Biermann, David
Partner: UNT Libraries Government Documents Department

A Study of the Factors Affecting the Range of Airplanes

Description: A study was made of the most important factors affecting the range of airplanes. Numerical examples are given showing the effects of different variables on the range of a two-engine airplane. The takeoff problems of long-range airplanes are analyzed.
Date: February 1937
Creator: Biermann, David
Partner: UNT Libraries Government Documents Department

The Effect of Compressibility on Eight Full-Scale Propellers Operating in the Take-Off and Climbing Range

Description: "Tests were made of eight full-scale propellers of different shape at various tip speeds up to about 1,000 feet per second. The range of blade-angle settings investigated was from 10 degrees to 30 degrees at the 0.75 radius. The results indicate that a loss in propulsive efficiency occurred at tip speeds from 0.5 to 0.7 the velocity of sound for the take-off and climbing conditions" (p. 517).
Date: May 18, 1938
Creator: Biermann, David & Hartman, Edwin P.
Partner: UNT Libraries Government Documents Department

The Aerodynamic Characteristics of Full-Scale Propellers Having 2, 3, and 4 Blades of Clark Y and R.A.F. 6 Airfoil Sections

Description: "Aerodynamic tests were made of seven full-scale 10-foot-diameter propellers of recent design comprising three groups. The first group was composed of three propellers having Clark Y airfoil sections and the second group was composed of three propellers having R.A.F. 6 airfoil sections, the propellers of each group having 2, 3, and 4 blades. The third group was composed of two propellers, the 2-blade propeller taken from the second group and another propeller having the same airfoil section and number of blades but with the width and thickness 50 percent greater" (p. 1).
Date: 1938
Creator: Hartman, Edwin P. & Biermann, David
Partner: UNT Libraries Government Documents Department

The Negative Thrust and Torque of Several Full-Scale Propellers and Their Application to Various Flight Problems

Description: "Negative thrust and torque data for 2, 3, and 4-blade metal propellers having Clark y and R.A.F. 6 airfoil sections were obtained from tests in the NACA 20-foot tunnel. The propellers were mounted in front of a radial engine nacelle and the blade-angle settings covered in the tests ranged from 15 degrees to 90 degrees. One propeller was also tested at blade-angle settings of 0 degree, 5 degrees, and 10 degrees" (p. 571).
Date: 1938
Creator: Hartman, Edwin P. & Biermann, David
Partner: UNT Libraries Government Documents Department

Full-Scale Tests of 4- and 6-Blade, Single- and Dual-Rotating Propellers, Special Report

Description: "Test of 10-foot diameter, 4- and 6-blade single- and dual-rotating propellers were conducted in the 20-foot propeller-research tunnel. The propellers were mounted at the front end of a streamline body incorporating spinners to house the hub portions. The effect of a symmetrical wing mounted in the slipstream was investigated. The blade angles investigated ranged from 20 degrees to 65 degrees; the latter setting corresponds to airplane speeds of over 500 miles per hour" (p. 1).
Date: August 1940
Creator: Biermann, David & Hartman, Edwin P.
Partner: UNT Libraries Government Documents Department

Full-Scale Tests of Several Propellers Equipped with Spinners, Cuffs, Airfoil and Round Shanks, and NACA 16-Series Sections, Special Report

Description: "Wind-tunnel tests of several propeller, cuff, and spinner combinations were conducted in the 20 foot propeller-research tunnel. Three propellers, which ranged in diameter from 8.4 to 11.25 feet, were tested at the front end of a streamline body incorporating spinners of two diameters. The tests covered a blade angle range from 20 deg to 65 deg. The effect of spinner diameter and propeller cuffs on the characteristics of one propeller was determined" (p. 1).
Date: October 1940
Creator: Biermann, David; Hartman, Edwin P. & Pepper, Edward
Partner: UNT Libraries Government Documents Department

Preliminary Tests of Nose- and Side- Entrance Blower Cooling Systems for Radial Engines, Special Report

Description: "Two cowling systems intended to reduce the drag and improve the low-speed cooling characteristics of conventional radial engine cowlings were tested in model form to determine the practicability of the methods. One cowling included a blower mounted on the rear face of a large propeller spinner which drew cooling air in through side entrance ducts located behind the equivalent engine orifice plate. The air was passed through the equivalent engine orifice plate from rear to front and out through a slot between the spinner and the engine plate" (p. 1).
Date: July 1939
Creator: Biermann, David & Valentine, E. Floyd
Partner: UNT Libraries Government Documents Department