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Calibration Tests of a Japanese Log Rodmeter

Description: A Japanese log rodmeter of the rotating-vane impeller type, with a commutator on the impeller shaft, was calibrated in Langley tank no. 1. The rotational speed of two impellers was determined for forward speeds up to 24 knots at angles of yaw up to ?10 0 . In general, the rotational speeds of two apparently identical impellers tested in the rodmeter decreased with increasing yaw angle, right yaw causing a greater decrease than left yaw. The difference in calibration between the two impellers was approximately the same as that produced by a change in yaw angle from 50 left to 50 right. Evidence of cavitation within the impeller fairing appeared at speeds above 24 knots.
Date: March 14, 1949
Creator: Mottard, Elmo J.
Partner: UNT Libraries Government Documents Department

A brief investigation of the effect of waves on the take-off resistance of a seaplane

Description: Report presenting testing to determine the resistance of a model of a seaplane with a length-beam ratio of 15 and a wing loading of 120 pounds per square foot was determined in smooth water and three wave heights under various conditions of load, speed, elevator setting, angle of dead rise, and center-of-gravity position.
Date: April 24, 1956
Creator: Mottard, Elmo J.
Partner: UNT Libraries Government Documents Department

Calibration Tests of a German Log Rodmeter

Description: A German log rodmeter of the pitot static type was calibrated in Langley tank no. 1 at speeds up to 34 knots and angles of yaw from 0 deg to plus or minus 10 3/4 degrees. The dynamic head approximated the theoretical head at 0 degrees yaw but decreased as the yaw was increased. The static head was negative and in general became more negative with increasing speed and yaw. Cavitation occurred at speeds above 31 knots at 0 deg yaw and 21 knots at 10 3/4 deg yaw.
Date: March 15, 1949
Creator: Mottard, Elmo J. & Stillman, Everette R.
Partner: UNT Libraries Government Documents Department

Average skin-friction drag coefficients from tank tests of a parabolic body of revolution (NACA RM-10)

Description: Average skin-friction drag coefficients were obtained from boundary-layer total-pressure measurements on a parabolic body of revolution (NACA rm-10, basic fineness ratio 15) in water at Reynolds numbers from 4.4 x 10(6) to 70 x 10(6). The tests were made in the Langley tank no. 1 with the body sting-mounted at a depth of two maximum body diameters. The arithmetic mean of three drag measurements taken around the body was in good agreement with flat-plate results, but, apparently because of the slight surface wave caused by the body, the distribution of the boundary layer around the body was not uniform over part of the Reynolds number range.
Date: 1954
Creator: Mottard, Elmo J & Loposer, J Dan
Partner: UNT Libraries Government Documents Department

Tank Tests of a Powered Model of a Compression Plane, NACA Model 171A-2

Description: The compression plane is intended for operation on or close to the surface of the water, and has a hull with a concave bottom which forms the upper surface of a tunnel into which air is forced under pressure to support part of the load. The results of the tests made in Langley tank no. 1 include values of the horizontal forces, trimming moment, and static pressure in the tunnel for a wide range of loads and speeds and two power conditions, and are presented in the form of curves against speed with load as a parameter. The results are scaled up to 10 times the model size for three conditions at which the model is self-propelled at a steady speed. Lift is obtained from the static pressure of air in the tunnel. In general, the ratio of the gross load to the total resistance increases with increase in load and decrease in speed. This ratio varies between l-7 and 5.7 at high speeds and has a maximum value of 7. The total resistance is nearly the same for both power conditions except at low speeds and heavy loads. No abrupt change in forces on the hull or flow around the hull occurs in. the region of zero draft. The centers of pressure are generally far aft. At the most efficient trim (1.2'), considerable bow-up moment would be required for practicable operation. There is no abrupt transition from the air-borne to the water- borne condition.
Date: July 1, 1948
Creator: Mottard, Elmo J. & Ruggles, Robert D.
Partner: UNT Libraries Government Documents Department