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 Serial/Series Title: NACA Research Memorandums
 Collection: National Advisory Committee for Aeronautics Collection
Evaluation of Gust and Draft Velocities from Flights of P-61c Airplanes within Thunderstorms. III - July 12, 1946 to July 18, 1946 at Orlando, Florida, Part 3, July 12, 1946 to July 18, 1946 at Orlando, Florida

Evaluation of Gust and Draft Velocities from Flights of P-61c Airplanes within Thunderstorms. III - July 12, 1946 to July 18, 1946 at Orlando, Florida, Part 3, July 12, 1946 to July 18, 1946 at Orlando, Florida

Date: November 5, 1946
Creator: Tolefson, H. B.
Description: The gust and draft velocities evaluated from acceleration and airspeed-altitude records taken by NACA instruments installed in P-61c airplanes participating in thunderstorm flights 9, 10, and 11 of July 12, 1946, July 17, 1946, and July 18, 1946, respectively, are presented in references 1 and 2 for previous flights. In accordance with a recent discussion with a member of the U.S. Weather Bureau staff, motion-picture records of the pilots' instrument panels for the present flights were inspected to note variations in the readings of a milliammeter used in conjunction with other equipment to indicate ambient air temperature. The inspection indicated that the instrument read zero throughout all traverses.
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Free-Spinning Tunnel Tests of a 1/20-Scale Model of the Chance Vought XF6U-1 Airplane, TED No. NACA 2390

Free-Spinning Tunnel Tests of a 1/20-Scale Model of the Chance Vought XF6U-1 Airplane, TED No. NACA 2390

Date: November 5, 1946
Creator: Klinar, Walter J.
Description: A spin investigation has been conducted in the Langley 20-foot free-spinning tunnel on a 1/20-scale model of the Chance Vought XF6U-1 airplane, The effects of control settings and movements upon the erect and inverted spin and recovery characteristics of the model were determined for the normal-fighter condition. The investigation also included tests for the take-off fighter condition (wing-tip tanks plus fuel added) spin-recovery parachutes, and simulated pilot escape. In general, for the normal-fighter condition, the model was extremely oscillatory in roll, pitch, and yaw. The angles of the fuselage varied from extremely flat to inverted attitudes, and the model rotated with the rudder in a series of short turns and glides. Recoveries by rudder reversal were rapid but the model would immediately go into a spin in the other direction. Recoveries by merely neutralizing the rudder were satisfactory when the elevator and ailerons were set to neutral, the ensuing flight path being a steep glide. Thus, it is recommended that all controls be neutralized for safe recovery from spins obtained on the airplane. With the external wing-tip tanks installed, the spins were somewhat less oscillatory in roll but recovery could not be obtained unless full-down elevator was used in conjunction ...
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Tank Tests of an Alternate Hull Form for the Consolidated Vultee PB2Y-3 Airplane

Tank Tests of an Alternate Hull Form for the Consolidated Vultee PB2Y-3 Airplane

Date: November 6, 1946
Creator: Land, Norman S. & Posner, Jack
Description: Tests have been made in Langley tank no. I of a dynamic model of the Consolidated Vultee PB2Y-3 airplane. These tests were made using an alternate hull form, the purpose of which was to reduce the bow spray and eliminate the landing instability which are objectionable features of the production design. The major differences from the PB2Y-3 hull included a deeper step to improve the landing stability , and a lengthened forebody and increased beam to reduce the sway in the propellers and on the flaps. The tests showed that the spray characteristics of the revised hull form were much better than that ot the production design. In addition the take-off and landing stability of the model with the alternate hull were satisfactory.
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An Investigation of the Icing and Heated-air De-icing Characteristics of the R-2600-13 Induction System

An Investigation of the Icing and Heated-air De-icing Characteristics of the R-2600-13 Induction System

Date: November 11, 1946
Creator: Chapman, Gilbert E.
Description: A laboratory investigation was made on a Holley 1685-HB carburetor mounted on an R-2600-13 supercharger assembly to determine the icing characteristics and the heated-air de-icing requirements of this portion of the B-25D airplane induction system. Icing has been found to be most prevalent at relatively small throttle openings and, consequently, all runs were made at simulated 60-percent normal rated power condition. Icing characteristics were determined during a series of 15-minute runs over a range of inlet-air conditions. For the de-icing investigation severe impact ice was allowed to form in the induction system and the time required for the recovery of 95 percent of the maximum possible air flow at the original throttle setting was then determined for a range of wet-bulb temperatures. Results of these runs showed that ice on the walls of the carburetor adapter and on the rim of the impeller-shroud portion of the supercharger diffuser plate did not affect engine operation at 60-percent normal rated power. Ice that adversely affected the air flow and the fuel-air ratio was formed only on the central web of the carburetor and then only when the inlet air was saturated or contained free moisture in excess of saturation. No serious ice ...
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Tank Tests of 1/5.5-Scale Forward Dynamic Model of the Columbia XJL-1 Amphibian - Langley Tank Model 208, TED No. NACA 2336

Tank Tests of 1/5.5-Scale Forward Dynamic Model of the Columbia XJL-1 Amphibian - Langley Tank Model 208, TED No. NACA 2336

Date: November 13, 1946
Creator: Havens, Robert F.
Description: Tests of a powered dynamic model of the Columbia XJL-1 amphibian were made in Langley tank no.1 to determine the hydrodynamic stability and spray characteristics of the basic hull and to investigate the effects of modifications on these characteristics. Modifications to the forebody chime flare, the step, and the afterbody, and an increase in the angle of incidence of the wing were included in the test program. The seaworthiness and spray characteristics were studied from simulated taxi runs in smooth and rough water. The trim limits of stability, the range of stable positions of the enter of gravity for take-off, and the landing stability were determined in smooth water. The aerodynamic lift, pitching moment, and thrust were determined at speeds up to take-off speed.
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Effect of Fuel Composition, Engine Operating Variables, and Spark-Plug Type and Condition on Preignition-Limited Performance of an R-2800 Cylinder

Effect of Fuel Composition, Engine Operating Variables, and Spark-Plug Type and Condition on Preignition-Limited Performance of an R-2800 Cylinder

Date: November 15, 1946
Creator: Pfender, John F.
Description: The preignition characteristics of the R-2800 cylinder, as effected by fuel consumption, engine operating variables, and spark plug type and condition, were evaluated. The effects on preignition-limited performance of various percentages of aromatics (benzene, toluene, cumene, xylene) in a base fuel of triptane were investigated. Two paraffins (triptane and S + 6.0 ml TEL/gal) and two refinery blends (28-R and 33-R) were preignition rated. The effect of changes in the following engine operating variables on preignition limit was determined: inlet-air temperature, rear spark plug gasket temperature, engine speed, spark advance, tappet clearance, and oil consumption. Preignition limits of the R-2800 cylinder using Champion C34S and C35S and AC-LS86, LS87, and LS88 spark plugs were established and the effect of spark plug deterioration was investigated. No definite trends in preignition-limited indicated mean effective pressure were indicated for aromatics as a class when increased percentages of different aromatics were added to a base fuel of triptane. Three types of fuel (aromatics, paraffins, and refinery blends) showed a preignition range for this cylinder from 65 to 104 percent when based on the performance of S plus 6.0 ml TEL per gallon as 100 percent. The R-2800 cylinder is therefore relatively insensitive to fuel ...
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Effects of Wing Flaps and Wing Duct Inlet on the Lift and Stalling Characteristics of a 1/4-Scale Partial-Span Model of the Republic XF-12 Airplane in the Langley 19-Foot Pressure Tunnel

Effects of Wing Flaps and Wing Duct Inlet on the Lift and Stalling Characteristics of a 1/4-Scale Partial-Span Model of the Republic XF-12 Airplane in the Langley 19-Foot Pressure Tunnel

Date: November 18, 1946
Creator: Graham, Robert R.; Martina, Albert P. & Salmi, Reino J.
Description: An investigation was conducted in the Langley 19-foot pressure tunnel to determine the lift, drag, pitching-moment and stalling characteristics fo a 1/4 -scale partial-span model of the left wing of the Republic XF-12 airplane. The effects of a duct inlet, located between the nacelles at the leading edge of the wing, on those characteristics were also investigated. The Reynolds numbers for the investigation covered a range from 4,500,000 to 8,600,000. The results of the investigation indicated that maximum lift coefficients of 1.36, 1.71, and 2.11 were measured on the model with flaps neutral and deflected 20 deg and 55 deg, respectively at a Reynolds number of 8,600,000. When the duct inlet was replaced by a basic airfoil nose the flap-neutral maximum-lift coefficient was increased from 1.36 to 1.41. The results also showed that at maximum lift with flaps neutral or deflected 55 deg. most of the area between the nacelles were stalled while only small areas on other portions of the model were stalled; when the duct inlet was replaced by the basic airfoil nose the stall was delayed to a slightly higher angle of attack but the nature of the stall was relatively unaffected.
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Performance of 19XB-2A Gas Turbine, 1, Effect of Pressure Ratio and Inlet Pressure on Turbine Performance for an Inlet Temperature of 800 degree R

Performance of 19XB-2A Gas Turbine, 1, Effect of Pressure Ratio and Inlet Pressure on Turbine Performance for an Inlet Temperature of 800 degree R

Date: November 18, 1946
Creator: Kohl, Robert C. & Larkin, Robert G.
Description: An investigation of the 19XB-2A gas turbine is being conducted at the Cleveland laboratory to determine the effect on turbine performance of various inlet pressures, inlet temperatures, pressure ratios, and wheel speeds. The engine of which this turbine is a component is designed to operate at an air flow of 30 pounds per second at a compressor rotor speed of 17,000 rpm at sea-level conditions. At these conditions the total-pressure ratio is 2.08 across the turbine and the turbine inlet total temperature is 2000 degrees R. Runs have been made with turbine inlet total pressures of 20, 30, 40, and 45 inches of mercury absolute for a constant total pressure ratio across the turbine of 2.40, the maximum value that could be obtained. Additional runs have been made with total pressure ratios of 1.50 and 2.00 at an inlet total pressure of 45 inches of mercury absolute. All runs were made with an inlet total temperature of 800 degrees R over a range of corrected turbine wheel speeds from 40 to 150 percent of the corrected speed at the design point. The turbine efficiencies at these conditions are presented.
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High-Speed Longitudinal-Stability and Control Characteristics of the Consolidated Vultee Lark Missile as Predicted from Wind-Tunnel Tests (TED No. NACA 2391)

High-Speed Longitudinal-Stability and Control Characteristics of the Consolidated Vultee Lark Missile as Predicted from Wind-Tunnel Tests (TED No. NACA 2391)

Date: November 19, 1946
Creator: Axelson, John A. & Martin, Andrew
Description: A high-speed wind-tunnel investigation of the aerodynamic characteristics of a full-scale model of the Consolidated Vultee Lark indicates that the missile possesses satisfactory longitudinal-stability and-control characteristics throughout the Mach number range from 0.2 to 0.85, but that the maximum lift coefficients developed are not high enough to insure interception of the target at high altitudes. A reduction in wing loading appears advisable. Although the static longitudinal stability at zero angle of attack changes with Mach number and with lift coefficient, satisfactory control should be possible at all times as the tails retain their relatively large effectiveness throughout the range of Mach numbers and lift coefficients tested. Minimum stability and maximum maneuverability occur around 0.80 Mach number and 0.2 lift coefficient, which corresponds to level flight conditions of the missile. The optimum ratio of tail-to-wing deflection is 0.4.
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Altitude-Wind-Tunnel Investigation of Performance of Several Propellers on YP-47M Airplane at High Blade Loading, 2, Curtiss 838-1C2-18R1 Four-Blade Propeller

Altitude-Wind-Tunnel Investigation of Performance of Several Propellers on YP-47M Airplane at High Blade Loading, 2, Curtiss 838-1C2-18R1 Four-Blade Propeller

Date: November 26, 1946
Creator: Wallner, Lewis E. & Sorin, Solomon M.
Description: An investigation was conducted in the Cleveland altitude wind tunnel to determine the performance of a Curtiss propeller with four 838-lC2-lSRl blades on a YP-47M airplane at high blade loadings and engine powers. The study was made for a range of power coefficients between 0.30 and 1.00 at free-stream Mach numbers of 0.40 and 0.50. The results of the force measurements indicate primarily the trend of propeller efficiency for changes in power coefficient or advance-diameter ratio, inasmuch as corrections for the effects of tunnel-wall constriction on the installation have not been applied. Slip-stream pressure surveys across the propeller disk are presented to illustrate blade thrust load distribution for several operating conditions. At a free-stream Mach number of 0.40, nearly constant peak efficiencies were obtained at power coefficients from 0.30 to 0.70. A change in power coefficient from 0.70 to 0.90 reduced the peak efficiency about 5 percent. Blade stall at the tip sections became evident for a power coefficient of 0.91 when the advance-diameter ratio was reduced to 1.87. At a free-stream Mach number of 0.50, the highest propeller efficiencies were obtained for power coefficients from 0.80 to 1.00 at advance-diameter ratios above 2.90. At advance-diameter ratios below 2.90, the ...
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