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  • 1
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    Rotor blade aerodynamic design (1989)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Aerodynamic performance aspects of rotor blade design are presented. Design considerations, aerodynamic constraints and design variables are described.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Integrated Multidisciplinary Optimization of Rotorcraft: A Plan for Development; p 10-13
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Performance and Vibratory Loads Data From a Wind-Tunnel Test of a Model Helicopter Main-Rotor Blade With a Paddle-Type Tip (1997)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An investigation was conducted in the Langley Transonic Dynamics Tunnel to obtain data to permit evaluation of paddle-type tip technology for possible use in future U.S. advanced rotor designs. Data was obtained for both a baseline main-rotor blade and a main-rotor blade with a paddle-type tip. The baseline and paddle-type tip blades were compared with regard to rotor performance, oscillatory pitch-link loads, and 4-per-rev vertical fixed-system loads. Data was obtained in hover and forward flight over a nominal range of advance ratios from 0.15 to 0.425. Results indicate that the paddle-type tip offers no performance improvements in either hover or forward flight. Pitch-link oscillatory loads for the paddle-type tip are higher than for the baseline blade, whereas 4-per-rev vertical fixed-system loads are generally lower.
    Keywords: Aerodynamics
    Type: NASA-TM-4754 , L-17558 , NAS 1.15:4754 , ARL-TR-1283 , ATCOM-TR-97-A-006
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Effect of blade planform variation on the forward-flight performance of small-scale rotors (1992)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An investigation was conducted in the Glenn L. Martin Wind Tunnel to determine the effect of blade planform variation on the forward-flight performance of four small-scale rotors. The rotors were 5.417 ft in diameter and differed only in blade planform geometry. The four planforms were: (1) rectangular; (2) 3:1 linear taper starting at 94 percent radius; (3) 3:1 linear taper starting at 75 percent radius; and (4) 3:1 linear taper starting at 50 percent radius. Each planform had a thrust-weighted solidity of 0.098. The investigation included forward-flight simulation at advance ratios from 0.14 to 0.43 for a range of rotor lift and drag coefficients. Among the four rotors, the rectangular rotor required the highest torque for the entire range of rotor drag coefficients attained at advanced ratios greater than 0.14 for rotor lift coefficients C sub L from 0.004 to 0.007. Among the rotors with tapered blades and for C sub L = 0.004 to 0.007, either the 75 percent tapered rotor or the 50 percent tapered rotor required the least amount of torque for the full range of rotor drag coefficients attained at each advance ratio. The performance of the 94 percent tapered rotor was generally between that of the rectangular rotor and the 75 and 50 percent tapered rotors at each advance ratio for this range of rotor lift coefficients.
    Keywords: AERODYNAMICS
    Type: NASA-TM-4345 , L-16994 , NAS 1.15:4345 , AVSCOM-TR-92-B-005 , AD-A250772
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    Aerodynamic characteristics of a rotorcraft airfoil designed for the tip region of a main rotor blade (1991)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A wind tunnel investigation was conducted to determine the 2-D aerodynamic characteristics of a new rotorcraft airfoil designed for application to the tip region (stations outboard of 85 pct. radius) of a helicopter main rotor blade. The new airfoil, the RC(6)-08, and a baseline airfoil, the RC(3)-08, were investigated in the Langley 6- by 28-inch transonic tunnel at Mach numbers from 0.37 to 0.90. The Reynolds number varied from 5.2 x 10(exp 6) at the lowest Mach number to 9.6 x 10(exp 6) at the highest Mach number. Some comparisons were made of the experimental data for the new airfoil and the predictions of a transonic, viscous analysis code. The results of the investigation indicate that the RC(6)-08 airfoil met the design goals of attaining higher maximum lift coefficients than the baseline airfoil while maintaining drag divergence characteristics at low lift and pitching moment characteristics nearly the same as those of the baseline airfoil. The maximum lift coefficients of the RC(6)-08 varied from 1.07 at M=0.37 to 0.94 at M=0.52 while those of the RC(3)-08 varied from 0.91 to 0.85 over the same Mach number range. At lift coefficients of -0.1 and 0, the drag divergence Mach number of both the RC(6)-08 and the RC(3)-08 was 0.86. The pitching moment coefficients of the RC(6)-08 were less negative than those of the RC(3)-08 for Mach numbers and lift coefficients typical of those that would occur on a main rotor blade tip at high forward speeds on the advancing side of the rotor disk.
    Keywords: AERODYNAMICS
    Type: NASA-TM-4264 , L-16855 , NAS 1.15:4264 , AVSCOM-TR-91-B-003 , AD-B156202L
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 5
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    High Lift, Low Pitching Moment Airfoils (1988)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Two families of airfoil sections which can be used for helicopter/rotorcraft rotor blades or aircraft propellers of a particular shape are prepared. An airfoil of either family is one which could be produced by the combination of a camber line and a thickness distribution or a thickness distribution which is scaled from these. An airfoil of either family has a unique and improved aerodynamic performance. The airfoils of either family are intended for use as inboard sections of a helicopter rotor blade or an aircraft propeller.
    Keywords: AERODYNAMICS
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 6
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    Two-dimensional aerodynamic characteristics of the OLS/TAAT airfoil (1988)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Two flight tests have been conducted that obtained extension pressure data on a modified AH-1G rotor system. These two tests, the Operational Loads Survey (OLS) and the Tip Aerodynamics and Acoustics Test (TAAT) used the same rotor set. In the analysis of these data bases, accurate 2-D airfoil data is invaluable, for not only does it allow comparison studies between 2- and 3-D flow, but also provides accurate tables of the airfoil characteristics for use in comprehensive rotorcraft analysis codes. To provide this 2-D data base, a model of the OLS/TAAT airfoil was tested over a Reynolds number range from 3 x 10 to the 6th to 7 x 10 to the 7th and between Mach numbers of 0.34 to 0.88 in the NASA Langley Research Center's 6- by 28-Inch Transonic Tunnel. The 2-D airfoil data is presented as chordwise pressure coefficient plots, as well as lift, drag, and pitching moment coefficient plots and tables.
    Keywords: AERODYNAMICS
    Type: NASA-TM-89435 , A-87132 , NAS 1.15:89435
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 7
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    An application of active surface heating for augmenting lift and reducing drag of an airfoil (1988)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Application of active control to separated flow on the RC(6)-08 airfoil at high angle of attack by localized surface heating is numerically simulated by integrating the compressible 2-D nonlinear Navier-Stokes equation solver. Active control is simulated by local modification of the temperature boundary condition over a narrow strip of the upper surface of the airfoil. Both mean and perturbed profiles are favorably altered when excited with the same natural frequency of the shear layer by moderate surface heating for both laminar and turbulent separation. The shear layer is found to be very sensitive to localized surface heating in the vicinity of the separation point. The excitation field at the surface sufficiently altered both the local as well as the global circulation to cause a significant increase in lift and reduction in drag.
    Keywords: AERODYNAMICS
    Type: NASA-TM-100563 , NAS 1.15:100563
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 8
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    Aerodynamic characteristics of two rotorcraft airfoils designed for application to the inboard region of a main rotor blade (1990)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A wind tunnel investigation was conducted to determine the 2-D aerodynamic characteristics of two new rotorcraft airfoils designed especially for application to the inboard region of a helicopter main rotor blade. The two new airfoils, the RC(4)-10 and RC(5)-10, and a baseline airfoil, the VR-7, were all studied in the Langley Transonic Tunnel at Mach nos. from about 0.34 to 0.84 and at Reynolds nos. from about 4.7 to 9.3 x 10 (exp 6). The VR-7 airfoil had a trailing edge tab which is deflected upwards 4.6 degs. In addition, the RC(4)-10 airfoil was studied in the Langley Low Turbulence Pressure Tunnel at Mach nos. from 0.10 to 0.44 and at Reynolds nos. from 1.4 to 5.4 x 10 (exp 6) respectively. Some comparisons were made of the experimental data for the new airfoils and the predictions of two different theories. The results of this study indicates that both of the new airfoils offer advantages over the baseline airfoil. These advantages are discussed.
    Keywords: AERODYNAMICS
    Type: NASA-TP-3009 , L-16737 , NAS 1.60:3009 , AVSCOM-TR-90-B-005
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 9
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    Effect of Blade Planform Variation on a Small-Scale Hovering Rotor (1990)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A hover test was conducted on a small-scale rotor model for three sets of tapered rotor blades and a baseline rectangular planform rotor blade. All configurations had the same airfoils, twist, and thrust-weighted solidity. The tapered blade planforms had taper initiating at 50, 75, and 94 percent of the blade radius with a taper ratio of 3 to 1 for each blade set. The experiment was conducted for a range of thrust coefficients, and the data were compared to the predictions of three hover analysis methods. The data show the 94 percent tapered blade was slightly more efficient at the higher rotor thrust levels. The other tapered planform rotors did not show the expected improvement over the baseline rotor, and all configurations had similar performance for low thrust coefficients. None of the analysis methods correlated well with the experimental data.
    Keywords: AERODYNAMICS
    Type: NASA-TM-4146 , L-16608 , NAS 1.15:4146 , AVSCOM-TM-89-B-009 , AD-A217873
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 10
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    Wind Tunnel Evaluation of a Model Helicopter Main-Rotor Blade With Slotted Airfoils at the Tip (2001)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: Data for rotors using unconventional airfoils are of interest to permit an evaluation of this technology's capability to meet the U.S. Army's need for increased helicopter mission effectiveness and improved safety and survivability. Thus, an experimental investigation was conducted in the Langley Transonic Dynamics Tunnel (TDT) to evaluate the effect of using slotted airfoils in the rotor blade tip region (85 to 100 percent radius) on rotor aerodynamic performance and loads. Four rotor configurations were tested in forward flight at advance ratios from 0.15 to 0.45 and in hover in-ground effect. The hover tip Mach number was 0.627, which is representative of a design point of 4000-ft geometric altitude and a temperature of 95 F. The baseline rotor configuration had a conventional single-element airfoil in the tip region. A second rotor configuration had a forward-slotted airfoil with a -6 deg slat, a third configuration had a forward-slotted airfoil with a -10 slat, and a fourth configuration had an aft-slotted airfoil with a 3 deg flap (trailing edge down). The results of this investigation indicate that the -6 deg slat configuration offers some performance and loads benefits over the other three configurations.
    Keywords: Aerodynamics
    Type: NASA/TP-2001-211260 , L-17776 , NAS 1.60:211260 , AMCOM/AFDD/TR-00-A-003 , ARL-TR-2154
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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