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Evaluation of Gust and Draft Velocities from Flights of F-61C Airplanes within Thunderstorms August 7, 1947 to August 13, 1947 at Clinton County Army Air Field, Ohio

Description: The gust and draft velocities from records of NACA instruments installed in P-61C airplanes participating in thunderstorm flights at Clinton County Army Air FIeld, Ohio, from August 7, 1947 to August 13, 1947 are presented.
Date: February 13, 1948
Creator: Funk, Jack
Partner: UNT Libraries Government Documents Department

Evaluation of Gust and Draft Velocities from Flights of P-61C Airplanes within Thunderstorms June 11, 1947 to July 11, 1947 at Clinton County Army Air Field, Ohio

Description: The gust and draft velocities from records of NACA instruments installed in P-61C airplanes participating in thunderstorm flights at Clinton County Army Air Field, Ohio, from June 11, 1947 to July 11, 1947 are presented.
Date: January 21, 1948
Creator: Funk, Jack
Partner: UNT Libraries Government Documents Department

Evaluation of Gust and Draft Velocities from Flights of P-61C Airplanes within Thunderstorms August 13, 1947 to August 15, 1947 at Clinton County Army Air Field, Ohio

Description: The gust and draft velocities from records of NACA instruments installed in P-61C airplanes participating in thunderstorm flights at Clinton County Army Air Field, Ohio, from August 13, 1947 to August 15, 1947 are presented.
Date: February 2, 1948
Creator: Funk, Jack
Partner: UNT Libraries Government Documents Department

Evaluation of Gust and Draft Velocities from Flights of P-61C Airplanes within Thunderstorms September 4, 1947 to September 5, 1947 at Clinton County Army Air Field, Ohio

Description: The gust and draft velocities from records of NACA instruments installed in P-61C airplanes participating in thunderstorm flights at Clinton County Army Air Field, Ohio, from September 4, 1947 to September 5, 1947 are presented.
Date: April 3, 1948
Creator: Funk, Jack
Partner: UNT Libraries Government Documents Department

Evaluation of Gust and Draft Velocities from Flights of P-61C Airplanes within Thunderstorms August 16, 1947 to August 20, 1947 at Clinton County Army Air Field, Ohio

Description: The gust and draft velocities from records of NACA instruments installed in P-61C airplanes participating in thunderstorm flights at Clinton County Army Air Field, Ohio, from August 16, 1947 to August 20, 1947 are presented.
Date: March 5, 1948
Creator: Funk, Jack
Partner: UNT Libraries Government Documents Department

Evaluation of Gust and Draft Velocities from Flights of P-61C Airplanes within Thunderstorms June 2, 1947 to June 7, 1947 at Clinton County Army Air Field, Ohio

Description: The gust and draft velocities from records of NACA instruments installed in P-61C airplanes participating in thunderstorm flights at Clinton County Army Air Field, Ohio, from June 2, 1947 to June 7, 1947, are presented.
Date: January 2, 1948
Creator: Funk, Jack
Partner: UNT Libraries Government Documents Department

Evaluation of Gust and Draft Velocities from Flights of P-61C Airplanes within Thunderstorms May 13, 1947 to May 29, 1947 at Clinton County Army Air Field, Ohio

Description: The gust and draft velocities evaluated from records of NACA instruments installed in P-61C airplanes participating in thunderstorm flights at Clinton County Army Air Field, Ohio, from May 13 to May 29, 1947 are presented.
Date: January 2, 1948
Creator: Tolefson, Harold B.
Partner: UNT Libraries Government Documents Department

Evaluation of Gust and Draft Velocities from Flights of P-61C Airplanes within Thunderstorms: September 5, 1946 to September 10, 1946 at Orlando, Florida

Description: Tables I and II of this report summarize the gust and draft velocity data for thunderstorm flights 31, 32, and 33 of September 5, 1946, September 6, 1946, and September 10, 1946, respectively. These data were evaluated from records of NACA instruments installed in P-61C airplanes and are of the type presented for previous flights. Table III summarizes the readings of a milliammeter which was used in conjunction with other equipment to indicate ambient air temperature during thunderstorm surveys. These data were read from motion-picture records of the instrument and include all cases in which variations in the instrument indications were noted for the present flights.
Date: 1947
Creator: Tolefson, H. B.
Partner: UNT Libraries Government Documents Department

Evaluation of Gust and Draft Velocities from Flights of P-61c Airplanes within Thunderstorms August 7, 1946 to August 13, 1946 at Orlando, Florida

Description: This report presents the results obtained from gust and draft velocity measurements within thunderstorms for the period August 7, 1946 to August, 13, 1946 at Orlando Florida. In several of the surveys, indications of ambient air temperature were obtained from photo-observer records. These data are summarized in the report.
Date: December 9, 1946
Creator: Tolefson, Harold B.
Partner: UNT Libraries Government Documents Department

Icing Frequencies Experienced During Climb and Descent by Fighter-Interceptor Aircraft

Description: "Data and analyses are presented on the relative frequencies of occurrence and severity of icing cloud layers encountered by jet aircraft in the climb and descent phases of flights to high altitudes. Fighter-interceptor aircraft operated by the Air Defense Command (USAF) at bases in the Duluth and Seattle areas collected the data with icing meters installed for a 1-year period. The project was part of an extensive program conducted by the NACA to collect Icing cloud data for evaluating the icing problem relevant to routine operations" (p. 1).
Date: July 1958
Creator: Perkins, Porter J.
Partner: UNT Libraries Government Documents Department

Photomicrographic Investigation of Spontaneous Freezing Temperatures of Supercooled Water Droplets

Description: A photomicrographic technique for investigating eupercooled. water droplets has been devised and. used. to determine the spontaneous freezing temperatures of eupercooled. water droplets of the size ordinarily found. in the atmosphere. The freezing temperatures of 4527 droplets ranging from 8.75 to 1000 microns in diameter supported on a platinum surface and 571 droplets supported on copper were obtained. The average spontaneous freezing temperature decreased with decrease in the size of the droplets. The effect of size on the spontaneous freezing temperature was particularly marked below 60 microns. Frequency-distribution curves of the spontaneous freezing temperatures observed for droplets of a given size were obtained. Although no droplet froze at a temperature above 20 0 F, all droplets melted at 32 F. Results obtained with a copper support did not differ essentially from those obtained with a platinum surface.
Date: July 1, 1950
Creator: Dorsch, R. G. & Hacker, P. T.
Partner: UNT Libraries Government Documents Department

Meteorological Analysis of Icing Conditions Encountered in Low-Altitude Stratiform Clouds

Description: Liquid-water content, droplet size, and temperature data measured during 22 flights in predominatly stratiform clouds through the 1948-49 and the 1949-50 winters are presented. Several icing encounters were of greater severity than those previously measured over the same geographical area, but were within the limits of similar measurements obtained over different terrain within the United States. An analysis of meteorological conditions existing during the 74 flights conducted for four winters indicated an inverse relation of liquid-water concentration to maximum horizontal extent of icing clouds. Data on the vertical extent of supercooled clouds are also presented. Icing conditions were most likely to occur in the southwest and northwest quadrants of a cyclone area, and least likely to occur in the southeast and northeast quadrants where convergent air flow and lifting over the associated warm frontal surface usually cause precipitation. Additional data indicated that, icing conditions were usually encountered in nonprecipitating clouds existing at subfreezing temperatures and were unlikely over areas where most weather observing stations reported the existence of precipitation. Measurements of liquid-water content obtained during 12 flights near the time and location of radiosonde observations were compared with theoretical values. The average liquid-water content of a cloud layer, as measured by the multicylinder technique, seldom exceeded two-thirds of that which could be released by adiabatic lifting. Local areas near the cloud tops equaled or occasionally exceeded the calculated maximum quantity of liquid water.
Date: March 1, 1951
Creator: Kline, D. B. & Walker, J. A.
Partner: UNT Libraries Government Documents Department

Maximum Evaporation Rates of Water Droplets Approaching Obstacles in the Atmosphere Under Icing Conditions

Description: When a closed body or a duct envelope moves through the atmosphere, air pressure and temperature rises occur ahead of the body or, under ram conditions, within the duct. If cloud water droplets are encountered, droplet evaporation will result because of the air-temperature rise and the relative velocity between the droplet and stagnating air. It is shown that the solution of the steady-state psychrometric equation provides evaporation rates which are the maximum possible when droplets are entrained in air moving along stagnation lines under such conditions. Calculations are made for a wide variety of water droplet diameters, ambient conditions, and flight Mach numbers. Droplet diameter, body size, and Mach number effects are found to predominate, whereas wide variation in ambient conditions are of relatively small significance in the determination of evaporation rates. The results are essentially exact for the case of movement of droplets having diameters smaller than about 30 microns along relatively long ducts (length at least several feet) or toward large obstacles (wings), since disequilibrium effects are then of little significance. Mass losses in the case of movement within ducts will often be significant fractions (one-fifth to one-half) of original droplet masses, while very small droplets within ducts will often disappear even though the entraining air is not fully stagnated. Wing-approach evaporation losses will usually be of the order of several percent of original droplet masses. Two numerical examples are given of the determination of local evaporation rates and total mass losses in cases involving cloud droplets approaching circular cylinders along stagnation lines. The cylinders chosen were of 3.95-inch (10.0+ cm) diameter and 39.5-inch 100+ cm) diameter. The smaller is representative of icing-rate measurement cylinders, while with the larger will be associated an air-flow field similar to that ahead of an airfoil having a leading-edge radius comparable with ...
Date: October 1, 1953
Creator: Lowell, H. H.
Partner: UNT Libraries Government Documents Department

Experimental Values of the Surface Tension of Supercooled Water

Description: The results of surface-tension measurements for supercooled water are presented. A total of 702 individual measurements of surface tension of triple-distilled water were made in the temperature range, 27 to -22.2 C, with 404 of these measurements at temperatures below 0 C. The increase in magnitude of surface tension with decreasing temperature, as indicated by measurements above 0 C, continues to -22.2 C. The inflection point in the surface-tension - temperature relation in the vicinity of 0 C, as indicated by the International Critical Table values for temperatures down to -8 C, is substantiated by the measurements in the temperature range, 0 to -22.2 C. The surface tension increases at approximately a linear rate from a value of 76.96+/-0.06 dynes per centimeter at -8 C to 79.67+/-0.06 dynes per centimeter at -22.2 C.
Date: October 1, 1951
Creator: Hacker, P. T.
Partner: UNT Libraries Government Documents Department

A Photographic Study of Freezing of Water Droplets Falling Freely in Air

Description: From Summary: "A photographic technique for investigating water droplets of diameter less than 200 microns falling freely in air at temperatures between 0 C and -50 C has been devised and used to determine: (1) The shape of frozen droplets, (2) The occurrence of collisions of partly frozen or of frozen and liquid droplets, and (3) The statistics on the freezing temperatures of individual free-falling droplets."
Date: February 25, 1952
Creator: Dorsch, Robert G. & Levine, Joseph
Partner: UNT Libraries Government Documents Department

Investigation of ice formation in the induction system of an aircraft engine 2: flight tests

Description: From Summary: "Flight tests were conducted on a twin-engine fighter airplane at pressure altitudes up to 10,000 feet with simulated conditions of moderate, heavy, and excessive rain to determine the increase in enthalpy of the charge air due to the turbosupercharger, to determine the rate of enthalpy increase of the charge air resulting from a sudden increase of engine power, and to compare the conditions that caused induction-system icing in flight with those that resulted in icing of the same carburetor and supercharger inlet elbow in laboratory tests."
Date: June 1946
Creator: Essex, Henry A.; Ellisman, Carl & Zlotowski, Edward D.
Partner: UNT Libraries Government Documents Department

Investigation of Meteorological Conditions Associated with Aircraft Icing in Layer-Type Clouds for 1947-48 Winter

Description: Rotating-cylinder measurements of the icing conditions encountered in flight during the winter of 1947-48 are presented. Liquid water content, drop size, and temperature data are shown to be consistent with previously measured conditions and with proposed maximum icing conditions in supercooled layer-type clouds. Cumulative frequency graphs of meteorological parameters indicate the frequency with which various icing conditions have been encountered in the Great Lakes area and surrounding states.
Date: January 1949
Creator: Kline, Dwight B.
Partner: UNT Libraries Government Documents Department

Variation of Local Liquid-Water Concentration About and Ellipsoid of Fineness Ratio 5 Moving in a Droplet Field

Description: From Summary: "Trajectories of water droplets about an ellipsoid of revolution with a fineness ratio of 5 (which often approximates the shape of an aircraft fuselage or missile) were computed with the aid of a differential analyzer. Analyses of these trajectories indicate that the local concentration of liquid water at various points about an ellipsoid in flight through a droplet field varies considerably and under some conditions may be several times the free-stream concentration."
Date: July 1954
Creator: Dorsch, Robert G. & Brun, Rinaldo J.
Partner: UNT Libraries Government Documents Department

A further investigation of the meteorological conditions conducive to aircraft icing

Description: Report presenting meteorological data from flight observations in icing conditions during the winter of 1946-47. Data on liquid water content, temperature, and mean-effective drop diameter are consistent with values previously proposed for maximum icing conditions. Results regarding the icing conditions in altostratus clouds, reexamination of previously proposed design conditions, relation between maximum liquid water content and temperature in layer clouds, typical icing conditions, maximum drop size, and drop-size distribution are provided.
Date: October 1947
Creator: Lewis, William; Kline, Dwight B. & Steinmetz, Charles P.
Partner: UNT Libraries Government Documents Department

Determination of rate, area, and distribution of impingement of water drops on various airfoils from trajectories obtained on the differential analyzer

Description: From Summary: "The trajectories of waterdrops in air flowing over airfoils are determined for three airfoil-angle-of-attack combinations using the differential analyzer to solve the differential equations of motion of the waterdrops. From these trajectories the rate of water impingement, the area of impingement, and the distribution of impingement are determined as functions of two dimensionless moduli. Comparisons are made of the rate of water impingement on these airfoils and the rate of water impingement on cylinders."
Date: February 16, 1949
Creator: Guibert, A. G.; Janssen, E. & Robbins, W. M.
Partner: UNT Libraries Government Documents Department

Determination of rate, area, and distribution of impingement of waterdrops on various airfoils from trajectories obtained on the differential analyzer

Description: From Summary: "The trajectories of waterdrops in air flowing over airfoils are determined for three airfoil - angle-of-attack combinations using the differential analyzer to solve the differential equations of motion of the waterdrops. From these trajectories the rate of water impingement, the area of impingement, and the distribution of impingement are determined as functions of two dimensionless moduli. Comparisons are made of the rate of water impingement on these airfoils and the rate of water impingement on cylinders."
Date: February 16, 1949
Creator: Guibert, A. G.; Janssen, E. & Robbins, W. M.
Partner: UNT Libraries Government Documents Department

Determination of rate, area, and distribution of impingement of of waterdrops on various airfoils from trajectories obtained on the differential analyzer

Description: From Summary: "The trajectories of waterdrops in air flowing over airfoils are determined for three airfoil-angle-of-attack combinations using the differential analyzer to solve the differential equations of motion of the waterdrops. From these trajectories the rate of water impingement, the area of impingement, and the distribution of impingement are determined as functions of two dimensionless moduli. Comparisons are made of the rate of water impingement on these airfoils and the rate of water impingement on cylinders."
Date: February 16, 1949
Creator: Guibert, A. G.; Janssen, E. & Robbins, W. M.
Partner: UNT Libraries Government Documents Department