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Effect of powered propellers on the aerodynamic characteristics and the porpoising stability of a dynamic model of a long-range flying boat

Description: Report discusses the results of two tests: "1) aerodynamic tests to determine the effect of the slipstream and thrust from the powered propellers on the lift and trimming-moment characteristics, and 2) hydrodynamic tests to determine the effect of the powered propellers on the range of stable locations of the center of gravity (from Introduction)." Large differences in the stable range between half-thrust and full-thrust conditions were observed. Three effects of power were also involved in the location of the stable range of the center of gravity.
Date: May 1943
Creator: Land, Norman S.
Partner: UNT Libraries Government Documents Department

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

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.
Date: November 6, 1946
Creator: Land, Norman S. & Posner, Jack
Partner: UNT Libraries Government Documents Department

Tank Tests of a 1/7-Size Powered Dynamic Model of the Grumman XJR2F-1 Amphibian: Spray Characteristics, Take-Off and Landing Stability in Smooth Water - Langley Tank Model 212, TED No. NACA 2378

Description: Tests of a model of the XJR2F-Y amphibian were made in Langley tank no. to determine the spray characteristics and the take-off and landing stability. At a gross load of 22,000 pounds full size, spray entered the propeller disk only at a very narrow range of speeds. The spray striking the flaps was not excessive and no appreciable wetting of the tail surfaces was noted. The trim limits of stability appeared to be satisfactory and the upper-limit porpoising was not violent. The stable range of center-of-gravity locations with flaps set 20deg was well aft of the desired operating range. However, with flaps up, the forward limit was about 18 percent mean aerodynamic chord and the aft limit about 28.5 percent mean aerodynamic chord at a load of 26,000 pounds and with elevators deflected -10deg. Under these conditions the location of the step is considered satisfactory. Tests showed that the effect of water in the nose-wheel well would be to move the forward limit aft about 2-percent mean aerodynamic chord. Without ventilation of the main step, the model skipped during landing at most trims, but this skipping was not violent. With the ventilation, the model skipped lightly only at trims where the afterbody keel was approximately parallel to the water (around 7.5 deg).
Date: December 4, 1946
Creator: Land, Norman S. & Zeck, Howrad
Partner: UNT Libraries Government Documents Department

Acceleration Measurements During Landing in Rough Water of a 1/7-Scale Dynamic Model of Grumman XJR2F-1 Amphibian - Langley Tank Model 212, TED No. NACA 2378

Description: Tests of a 1/7 size model of the Grumman XJR2F-1 amphibian were made in Langley tank no.1 to examine the landing behavior in rough water and to measure the normal and angular accelerations experienced by the model during these landings. All landings were made normal to the direction of wave advance, a condition assumed to produce the greatest accelerations. Wave heights of 4.4 and 8.0 inches (2.5 and 4.7 ft, full size) were used in the tests and the wave lengths were varied between 10 and 50 feet (70 and 350 ft, full size). Maximum normal accelerations of about 6.5g were obtained in 4.4 inch waves and 8.5g were obtained in 8.0 inch waves. A maximum angular acceleration corresponding to 16 radians per second per second, full size, was obtained in the higher waves. The data indicate that the airplane will experience its greatest accelerations when landing in waves of about 20 feet (140 ft, full size) in length.
Date: May 6, 1947
Creator: Land, Norman S. & Zeck, Howard
Partner: UNT Libraries Government Documents Department

Tank Tests of a 1/7-Size Dynamic Model of the Grumman XJR2F-1 Amphibian to Determine the Effect of Slotted- and Split-Type Flaps on Take-Off Stability - NACA Model 212, TED No. NACA 2378

Description: Additional tests of a 1/7-size model of the Grumman XJR2F-1 amphibian were made in Langley tank no. 1 to compare the behavior during take-off of the model equipped with split- and slotted-type flaps. The slotted flag had a large effect on locating the forward center-of-gravity limits for stable take-offs. Stable take-offs within the normal operating range of positions of the center of gravity could be made with the split flaps deflected 45deg or with the slotted flaps deflected less than 20deg. At flap deflections required for similar take-off stability, the use of split-flaps resulted lower take-off speeds than the use of slotted flaps. An increase in forward acceleration from 1.1 to 4.8 feet per second per second moved the center-of-gravity limit forward approximately 3-percent mean aerodynamic chord.
Date: February 6, 1947
Creator: Land, Norman S. & Zeck, Howard
Partner: UNT Libraries Government Documents Department

Force Characteristics in the Submerged and Planing Condition of a 1/5.78-Scale Model of a Hydro-Ski-Wheel Combination for the Grumman JRF-5 Airplane. TED No. NACA DE 357

Description: Force characteristics determined from tank tests of a 1/5.78 scale model of a hydro-ski-wheel combination for the Grumman JRF-5 airplane are presented. The model was tested in both the submerged and planing conditions over a range of trim, speed, and load sufficiently large to represent the most probable full-size conditions.
Date: February 20, 1952
Creator: Land, Norman S. & Pelz, Charles A.
Partner: UNT Libraries Government Documents Department

An Investigation of Hydrofoils in the NACA Tank I : Effect of Dihedral and Depth of Submersion

Description: Tests were conducted on hydrofoil assemblies approximating an arrangement for use under seaplanes or surface boats. A series of hydrofoils, each supported by two struts, was towed at various depths ranging from partial submersions to a depth of 5-chord lengths. At depths greater than 4 or 5 chords, the influence of the surface of the water is small; hydrofoils operating at low speed will have characteristics similar to those of airfoils of the same section.
Date: September 1, 1942
Creator: Land, Norman S. & Benson, James M.
Partner: UNT Libraries Government Documents Department

Preliminary tests in the NACA tank to investigate the fundamental characteristics of hydrofoils

Description: Report discusses an investigation into the hydrodynamic properties and general behavior of simple hydrofoils. The experimental results are presented as curves of the lift and drag coefficients plotted against speed for angles of attack and depths. Properly designed hydrofoil sections were determined to have excellent characteristics and a significant reduction in the speed of cavitation.
Date: September 1940
Creator: Ward, Kenneth E. & Land, Norman S.
Partner: UNT Libraries Government Documents Department

The landing stability of a powered dynamic model of a flying boat with a 30 degree v-step and with two depths of transverse step

Description: Report discusses tests conducted using a model of a four-engine long-range flying boat with a 30 degree V-step and two different transverse steps of comparable positions and depths. The limits of stability, landing speed, and landing characteristics of the different models are presented.
Date: February 1944
Creator: Parkinson, John B. & Land, Norman S.
Partner: UNT Libraries Government Documents Department

Transonic flutter investigation of a fighter-airplane wing model and comparison with a systematic plan-form series

Description: Report presenting an investigation of the transonic flutter characteristics at zero lift of a model of a wing for a new fighter airplane. The characteristics were found to be similar to those of a comparable systematic plan-form series of models described in previous reports. Results regarding visual observations, damping, flutter-speed ratio, and ratio of experimental sustained flutter speeds to reference flutter speeds are provided.
Date: October 7, 1955
Creator: Land, Norman S. & Abbott, Frank T., Jr.
Partner: UNT Libraries Government Documents Department

Transonic flutter investigation of an all-moveable horizontal tail for a fighter airplane

Description: Report presenting an investigation of transonic flutter of a model of an all-movable horizontal tail for a fighter airplane. Characteristics of the model included an aspect ratio of 3.3, a taper ratio of 0.42, and 35 degrees of sweepback of the quarter-chord line. Information regarding analytical analysis, experimental results, and comparison with theory is provided.
Date: January 14, 1957
Creator: Land, Norman S. & Abbott, Frank T., Jr.
Partner: UNT Libraries Government Documents Department

Full-Scale Hydrodynamic Evaluation of a Modified Navy J4F-2 Amphibian with a 0.425-Scale XP5M-1 Hull Bottom. TED No. NACA DE325

Description: An investigation was made to evaluate the hydrodynamic qualities of a 0.425-scale model of the Navy XP5M-1 hull, which was installed on a modified Navy J4F-2 amphibian. Longitudinal and directional stability during take-off and landing, low-speed maneuverability, spray characteristics, and take-off performance were investigated. The behavior of the airplane in moderately rough water was also observed. The opinions of three pilots have been correlated with the data.
Date: December 7, 1949
Creator: Land, Norman S.; Elliott, John M. & Christopher, Kenneth W.
Partner: UNT Libraries Government Documents Department

The resistance of three series of flying boat-hulls as affected by length-beam ratio

Description: Report presents correlation of data obtained from several independent length-beam-ratio investigations to determine the general effect of length-beam ratio on the resistance characteristics of three series of flying-boat hulls. An optimum length-beam ratio was found beyond which no further reduction in hydrodynamic resistance occurred. The optimum ratio depended on the hull lines of any given mode series.
Date: October 1945
Creator: Land, Norman S.; Bidwell, Jerold M. & Goldenbaum, David M.
Partner: UNT Libraries Government Documents Department