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  • Aircraft Design, Testing and Performance  (68)
  • FLUID MECHANICS AND HEAT TRANSFER  (23)
  • 1950-1954  (91)
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  • 1
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    Fuselage Pressures Measured on the Bell X-1 Research Airplane in Transonic Flight (1953)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Pressure-distribution measurements have been made on the fus elage of the Bell X- 1 research airplane. Data are presented for angles of attack from 2 deg. to 8 deg. during pull-ups at Mach numbers of about 0.78, 0.85, 0.88, and 1.02. The results of the investigation indicated that a large portion of the load carried by the fuselage was in the vicinity of the wing and may be attributed to wing-to-fuselage carryover. The presence of the wing from the 41 to 60 percent fuselage stations influenced the fuselage pressures from about 30 to 65 percent fuselage length at Mach numbers of approximat ely 0.78, 0.85, and 0.88, and from about 35 to 80 percent fuselage length at a Mach number of approximately 1.02. The fuselage contributed about 20 percent of the total airplane normal-force coefficient. The center of pressure of the fuselage load throughout the tests was located from 41 to 51 percent fuselage length, which corresponds to the forward half of the wing root-chord location.
    Keywords: Aircraft Design, Testing and Performance
    Type: NACA-RM-L53I15
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Effect of a Rapid Blade-Pitch Increase on the Thrust and Induced-Velocity Response of a Full-Scale Helicopter Rotor (1953)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A method has been proposed for predicting the effect of a rapid blade-pitch increase on the thrust and induced-velocity response of a helicopter rotor. General equations have been derived for the ensuing motion of the helicopter. These equations yield time histories of thrust, induced velocity, and helicopter vertical velocity for given rates of blade-pitch-angle changes and given rotor-angular-velocity time histories. The results of the method have been compared with experimental results obtained with a rotor mounted on the Langley helicopter test tower. The calculated and experimental results are in good agreement, although, in general, the calculated thrust-coefficient overshoots are about 10 percent greater than those obtained experimentally.
    Keywords: Aircraft Design, Testing and Performance
    Type: NACA-TN-3044
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Effect of Mach Number on the Flow and Application of Compressibility Corrections in a Two-Dimensional Subsonic-Transonic Compressor Cascade Having Varied Porous-Wall Suction at the Blade Tips (1952)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A cascade of 65-(12)10 compressor blades was tested at one geometric setting over a range of inlet Mach number from 0.12 to 0.89. Two groups of data are presented and compared: the first from the cascade operating conventionally with no boundary-layer control, and the second with the boundary layer controlled by a combination of upstream slot suction and porous-wall suction at the blade tips. A criterion for two-dimensionality was used to specify the degree of boundary-layer control by suction to be applied. The data are presented and an analysis is made to show the effect of Mach number on turning angle, blade wake, pressure distribution about the blade profile and static-pressure rise. The influence of boundary-layer control on these parameters as well as on the secondary losses is illustrated. A system of correlating the measured static-pressure rise through the cascade with the theoretical isentropic values is presented which gives good agreement with the data. The pressure distribution about the blade profile for an inlet Mach number of 0.21 is corrected with the Prandtl-Glauert, Karman-Tsien, and vector-mean velocity - contraction coefficient compressibility correction factors to inlet Mach numbers of 0.6 and 0.7. The resulting curves are compared with the experimental pressure distributions for inlet Mach numbers of 0.6 and 0.7 so that the validity of applying the three corrections can be evaluated.
    Keywords: Aircraft Design, Testing and Performance
    Type: NACA-TN-2649
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    Empirical Relation Between Induced Velocity, Thrust, and Rate of Descent of a Helicopter Rotor as Determined by Wind-tunnel Tests on Four Model Rotors (1951)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The empirical relation between the induced velocity, thrust, and rate of vertical descent of a helicopter rotor was calculated from wind tunnel force tests on four model rotors by the application of blade-element theory to the measured values of the thrust, torque, blade angle, and equivalent free-stream rate of descent. The model tests covered the useful range of C(sub t)/sigma(sub e) (where C(sub t) is the thrust coefficient and sigma(sub e) is the effective solidity) and the range of vertical descent from hovering to descent velocities slightly greater than those for autorotation. The three bladed models, each of which had an effective solidity of 0.05 and NACA 0015 blade airfoil sections, were as follows: (1) constant-chord, untwisted blades of 3-ft radius; (2) untwisted blades of 3-ft radius having a 3/1 taper; (3) constant-chord blades of 3-ft radius having a linear twist of 12 degrees (washout) from axis of rotation to tip; and (4) constant-chord, untwisted blades of 2-ft radius. Because of the incorporation of a correction for blade dynamic twist and the use of a method of measuring the approximate equivalent free-stream velocity, it is believed that the data obtained from this program are more applicable to free-flight calculations than the data from previous model tests.
    Keywords: Aircraft Design, Testing and Performance
    Type: NACA-TN-2474
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 5
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    An Analysis of the Autorotative Performance of a Helicopter Powered by Rotor-Tip Jet Units (1950)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The autorotative performance of an assumed helicopter was studied to determine the effect of inoperative jet units located at the rotor-blade tip on the helicopter rate of descent. For a representative ramjet design, the effect of the jet drag is to increase the minimum rate of descent of the helicopter from about 1,OO feet per minute to 3,700 feet per minute when the rotor is operating at a tip speed of approximately 600 feet per second. The effect is less if the rotor operates at lower tip speeds, but the rotor kinetic energy and the stall margin available for the landing maneuver are then reduced. Power-off rates of descent of pulse-jet helicopters would be expected to be less than those of ramjet. helicopters because pulse jets of current design appear to have greater ratios of net power-on thrust to power-off, drag than currently designed rain jets. Iii order to obtain greater accuracy in studies of autorotative performance, calculations in'volving high power-off rates of descent should include the weight-supporting effect of the fuselage parasite-drag force and the fact that the rotor thrust does not equal the weight of the helicopter.
    Keywords: Aircraft Design, Testing and Performance
    Type: NACA-TN-2154
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 6
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    The Effect of Blunt-Trailing-Edge Modifications on the High-Speed Stability and Control Characteristics of a Swept-Wing Fighter Airplane (1954)
    In:  CASI
    Details
    Publication Date: 2019-05-25
    Description: An investigation was conducted on a 35 deg swept-wing fighter airplane to determine the effects of several blunt-trailing-edge modifications to the wing and tail on the high-speed stability and control characteristics and tracking performance. The results indicated significant improvement in the pitch-up characteristics for the blunt-aileron configuration at Mach numbers around 0.90. As a result of increased effectiveness of the blunt-trailing-edge aileron, the roll-off, customarily experienced with the unmodified airplane in wings-level flight between Mach numbers of about 0.9 and 1.0 was eliminated, The results also indicated that the increased effectiveness of the blunt aileron more than offset the large associated aileron hinge moment, resulting in significant improvement in the rolling performance at Mach numbers between 0.85 and 1.0. It appeared from these results that the tracking performance with the blunt-aileron configuration in the pitch-up and buffeting flight region at high Mach numbers was considerably improved over that of the unmodified airplane; however, the tracking errors of 8 to 15 mils were definitely unsatisfactory. A drag increment of about O.OOl5 due to the blunt ailerons was noted at Mach numbers to about 0.85. The drag increment was 0 at Mach numbers above 0.90.
    Keywords: Aircraft Design, Testing and Performance
    Type: NACA-RM-A54C31
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 7
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    Analogy Between Mass and Heat Transfer with Turbulent Flow (1953)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An analysis of combined heat and mass transfer from a flat plate has been made in terms of Prandtl t s simplified physical concept of the turbulent boundary layer. The results of the analysis show that for conditions of reasonably small heat and mass transfer, the ratio of the mass-and heat-transfer coefficients is dependent on the Reynolds number of the boundary layer, the Prandtl number of the medium of diffusion, and the Schmidt number of the diffusing fluid in the medium of diffusion. For the particular case of water evaporating into air, the ratio of mass-transfer coefficient to heat-transfer coefficient is found to be slightly greater than unity.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NACA-TN-3045
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 8
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    Impingement of Water Droplets on NACA 65A004 Airfoil at 8 deg Angle of Attack (1954)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The trajectories of droplets in the air flowing past an NACA 65AO04 airfoil at an angle of attack of 8 deg were determined.. The amount of water in droplet form impinging on the airfoil, the area of droplet impingement, and the rate of droplet impingement per unit area on the airfoil surface were calculated from the trajectories and presented to cover a large range of flight and atmospheric conditions. These impingement characteristics are compared briefly with those previously reported for the same airfoil at an angle of attack of 4 deg.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NACA-TN-3155
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 9
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    Impingement of Water Droplets on a Cylinder in an Incompressible Flow Field and Evaluation of Rotating Multicylinder Method for Measurement of Droplet-Size Distribution, Volume-Median Droplet-Size, and Liquid-Water Content in Clouds (1953)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NACA-TN-2904
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 10
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    Penetration of Air Jets Issuing from Circular, Square, and Elliptical Orifices Directed Perpendicularly to an Air Stream (1950)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An experimental investigation was conducted to determine the penetration of air jets d.irected perpendicularlY to an air stream. Jets Issuing from circular, square, and. elliptical orifices were investigated. and. the jet penetration at a position downstream of the orifice was determined- as a function of jet density, jet velocity, air-stream d.enaity, air-stream velocity, effective jet diameter, and. orifice flow coeffIcient. The jet penetrations were determined for nearly constant values of air-stream density at three tunnel-air velocities arid for a large range of Jet velocities and. densities. The results were correlated in terms of dimensionless parameters and the penetrations of the various shapes were compared. Greater penetration was obtained. with the square orifices and the elliptical orifices having an axis ratio of 4:1 at low tunnel-air velocities and low jet pressures than for the other orifices investigated. The square orifices gave the best penetrations at the higher values of tunnel-air velocity and jet total pressure.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NACA-TN-2019
    Format: application/pdf
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