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  • Cell & Developmental Biology  (1,190)
  • Seismology  (46)
  • Aircraft Propulsion and Power  (21)
  • 1940-1944  (644)
  • 1935-1939  (613)
Collection
Keywords
Publisher
Years
Year
  • 1
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    Tandem Air Propellers (1937)
    In:  CASI
    Details
    Publication Date: 2019-08-26
    Description: Tests of 2-blade, adjustable-pitch, counterrotating tandem model propellers, adjusted to absorb equal power at maximum efficiency, were made at Stanford University. The characteristics, for 15 degrees, 25 degrees, 35 degrees, and 45 degrees pitch settings at 0.75 R of the forward propeller and for 8 1/2%, 15% and 30% diameter spacings, were compared with those of 2-blade and 4-blade propellers of the same blade form. The tests showed that the efficiency of the tandem propellers was from 0.5% to 4% greater than that of a 4-blade propeller and, at the high pitch settings, not appreciable inferior to that of a 2-blade propeller. It was found that the rear tandem propeller should be set at a pitch angle slightly less than that of the forward propeller to realize the condition of equal power at maximum efficiency. Under this condition the total power absorbed by the tandem propellers was from 3% to 9% more than that absorbed by the 4-blade propeller and about twice that absorbed by a 2-blade propeller.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-SR-66
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Compressibility and Heating Effects on Pressure Loss and Cooling of a Baffled Cylinder Barrel (1944)
    In:  CASI
    Details
    Publication Date: 2019-08-17
    Description: Theoretical investigations have shown that, because air is compressible, the pressure-drop requirements for cooling an air-cooled engine will be much greater at high altitudes and high speeds than at sea level and low speeds. Tests were conducted by the NACA to obtain some experimental confirmation of the effect of air compressibility on cooling and pressure loss of a baffled cylinder barrel and to evaluate various methods of analysis. The results reported in the present paper are regarded as preliminary to tests on single-cylinder and multi-cylinder engines. Tests were conducted over a wide range of air flows and density altitudes.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-TR-783
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    NACA Investigation of a Jet-Propulsion System Applicable to Flight (1943)
    In:  CASI
    Details
    Publication Date: 2019-08-13
    Description: Following a brief history of the NACA investigation of jet propulsion, a discussion is given of the general investigation and analysis 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.
    Keywords: Aircraft Propulsion and Power
    Type: NACA/TR-802
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    Aerodynamic Heat-Power Engine Operating on a Closed Cycle (1942)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Hot-air engines with dynamic compressors and turbines offer new prospects of success through utilization of units of high efficiencies and through the employment of modern materials of great strength at high temperature. Particular consideration is given to an aerodynamic prime mover operating on a closed circuit and heated externally. Increase of the pressure level of the circulating air permits a great increase of limit load of the unit. This also affords a possibility of regulation for which the internal efficiency of the unit changes but slightly. The effect of pressure and temperature losses is investigated. A general discussion is given of the experimental installation operating at the Escher Wyss plant in Zurich for a considerable time at high temperatures.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-TM-1034 , Zeitschrift des Vereines Deutscher Lagenieure; 85; 22; 491-500
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 5
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    Investigation of Single Stage Axial Fans (1944)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The following investigations are connected with experiments on fans carried out by the author in the Gouttingen Aerodynamic Laboratory within the framework of the preliminary experiments for the new Gouttingen wind-tunnel project. A fan rotor was developed which had very high efficiency at the design point corresponding to moderate pressure and which, in addition, could operate at a proportionally high pressure, rise. To establish the determining operating factors the author carried out extensive theoretical investigation in Hannover. In this it was necessary, to depart from the usual assumption of vanishing radial velocities. The calculations were substantially lightened by the introduction of diagrams. The, first part of the.report describes the theoretical investigations; the second, the experiments carried out at Gouttingen.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-TM-1062 , Luftfahyrtforschung; 14; 7; 325-346
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 6
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    Performance Characteristics of an Aircraft Engine with Exhaust Turbine Supercharger, Special Report (1941)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: The Pratt and Whitney Aircraft company and the Naval Aircraft Factory of the United States Navy cooperated in a laboratory and flight program of tests on an exhaust turbine supercharger. Two series of dynamometer tests of the engine super-charger combination were completed under simulated altitude conditions. One series of hot gas-chamber tests was conducted by the manufacturer of the supercharger. Flight demonstrations of the supercharger installed in a twin-engine flying boat were terminated by failure of the turbine wheels. The analysis of the results indicated that a two-stage supercharger with the first-stage exhaust turbine driven will deliver rated power for a given indicated power to a higher altitude, will operate more efficiently, and will require simpler controls than a similar engine with the first stage of the supercharger driven from the crankshaft through multispeed gears.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-SR-194
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 7
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    Wind-Tunnel Tests of Several Model Tractor-Propeller and Pusher-Propeller Wing Extension-Shaft Arrangements, Special Report (1941)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: Tests were made in the 20-foot propeller-research tunnel to investigate the possibility of obtaining increased net efficiencies of propeller-nacelle units by enclosing the engines in the wings and by using extension shafts. A wing of 5-foot chord was fitted with a propeller drive assembly providing for several axial locations of tractor propellers and pusher propellers. A three-blade 4-foot propeller and a three-blade 3 1/2-foot propeller of special design were tested in this wing with spinners and fairings ranging in diameter from 6 to 16 inches. A 16-inch NACA cowling was tested for comparative purposes. Two types of cuffs were also employed. It was found that the net efficiency of a conventional round-shank propeller mounted on an extension shaft in front of or behind a wing increased with an increase in the diameter of the spinner and the shaft housing within the scope of the tests. The largest spinner used had a diameter that might favorably compare with that of a radial engine cowling. The efficiencies for the pusher position appeared to be more critically affected by spinner size than those for the tractor position. The spinners with large diameters for the pusher position resulted in a higher efficiency than those for the corresponding tractor arrangements; the reverse was true for the small spinners. The use of propeller cuffs in combination with a spinner of small diameter generally resulted in net efficiencies that were comparable with those found for the large-spinner combinations.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-SR-196
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 8
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    Tandem Air Propellers - II (1939)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: Tests of three-blade, adjustable-pitch counterrotating tandem model propellers, adjusted to absorb equal power at maximum efficiency of the combination, were made at Stanford University. The aerodynamic characteristics, for blade-angle settings of 15, 25, 35, 45, 55, and 65 degrees at 0.75R of the forward propeller and for diameters spacings of 8-1/2, 15 and 30% were compared with those of three-blade and six-blade propellers of the same blade form. It was found that, in order to realize the condition of equal power at maximum efficiency, the blade angles for the rear propeller must be generally less than for the forward propeller, the difference increasing the blade angle. The tests showed that, at maximum efficiency, the tandem propellers absorb about double the power of three-blade propellers and about 8% more power than six-blade propellers having the pitch of the forward propeller of the tandem combination. The maximum efficiency of the tandem propellers was found to be from 2-15% greater than for six-blade propellers, the difference varying directly with blade angle. It was also found that the maximum efficiency of the tandem propellers was greater than that of a three-blade propeller for blade angles at 0.75R of 25 degrees or more. The difference in maximum efficiency again varied directly with blade angle, being about 9% for 65 degrees at 0.75R.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-SR-126
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 9
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    Engine Operation in Flight for Minimum Fuel Consumption (1939)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: Engine and airplane performance data have been gathered from various sources and analyzed to determine indications of the most economical methods of flight operation from a consideration of fuel expenditure. The analysis includes the influence of such facts as fuel-air ratio, engine speed, engine knock, altitude, cylinder cooling, spark timing, and limits of cruising brake mean effective pressure. The results indicate that the cheapest power is obtained with approximately correct mixture at low engine speed and highest permissible manifold pressure. If more power is desired, the methods of obtaining it are, in order of fuel economy: (a) increasing the engine speed and maintaining safe cylinder temperatures by cooling; (b) retarding the spark or cooling further to permit higher manifold pressure; and, (c) riching the mixture. The analysis further shows that the maximum time endurance of flight occurs at the air speed corresponding to minimum thrust horsepower required and with minimum practicable engine speed. Maximum mileage per pound of fuel is obtained at slightly higher air speed. The fuel-air ratio should be approximately the theoretically correct ratio in both cases. For an engine equipped with a geared supercharger, as in the example presented, and with knock as the limiting condition, a comparison of operation at sea level and at 6,000 feet shoes flight at altitude to be more economical on the basis of both range and endurance.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-SR-134
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 10
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    Experimental Determination of Exhaust Gas Thrust, Special Report (1940)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: This investigation presents the results of tests made on a radial engine to determine the thrust that can be obtained from the exhaust gas when discharged from separate stacks and when discharged from the collector ring with various discharge nozzles. The engine was provided with a propeller to absorb the power and was mounted on a test stand equipped with scales for measuring the thrust and engine torque. The results indicate that at full open throttle at sea level, for the engine tested, a gain in thrust horsepower of 18 percent using separate stacks, and 9.5 percent using a collector ring and discharge nozzle, can be expected at an air speed of 550 miles per hour.
    Keywords: Aircraft Propulsion and Power
    Type: NACA-SR-139
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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