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  • 1
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    Laminar-flow wind tunnel experiments (1989)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Although most of the laminar flow airfoils recently developed at the NASA Langley Research Center were intended for general aviation applications, low-drag airfoils were designed for transonic speeds and wind tunnel performance tested. The objective was to extend the technology of laminar flow to higher Mach and Reynolds numbers and to swept leading edge wings representative of transport aircraft to achieve lower drag and significantly improved operation costs. This research involves stabilizing the laminar boundary layer through geometric shaping (Natural Laminar Flow, NLF) and active control involving the removal of a portion of the laminar boundary layer (Laminar-Flow Control, LFC), either through discrete slots or perforated surface. Results show that extensive regions of laminar flow with large reductions in skin friction drag can be maintained through the application of passive NLF boundary-layer control technologies to unswept transonic wings. At even greater extent of laminar flow and reduction in the total drag level can be obtained on a swept supercritical airfoil with active boundary layer-control.
    Keywords: AERODYNAMICS
    Type: Transonic Symposium: Theory, Application and Experiment, Volume 2; p 105-145
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Wind tunnel results of the high-speed NLF(1)-0213 airfoil (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Wind tunnel tests were conducted to evaluate a natural laminar flow airfoil designed for the high speed jet aircraft in general aviation. The airfoil, designated as the High Speed Natural Laminar Flow (HSNLF)(1)-0213, was tested in two dimensional wind tunnels to investigate the performance of the basic airfoil shape. A three dimensional wing designed with this airfoil and a high lift flap system is also being evaluated with a full size, half span model.
    Keywords: AERODYNAMICS
    Type: Research in Natural Laminar Flow and Laminar-Flow Control, Part 3; p 697-726
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Airfoil modification effects on subsonic and transonic pressure distributions and performance for the EA-6B airplane (1995)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Longitudinal characteristics and wing-section pressure distributions are compared for the EA-6B airplane with and without airfoil modifications. The airfoil modifications were designed to increase low-speed maximum lift for maneuvering, while having a minimal effect on transonic performance. Section contour changes were confined to the leading-edge slat and trailing-edge flap regions of the wing. Experimental data are analyzed from tests in the Langley 16-Foot Transonic Tunnel on the baseline and two modified wing-fuselage configurations with the slats and flaps in their retracted positions. Wing modification effects on subsonic and transonic performance are seen in wing-section pressure distributions of the various configurations at similar lift coefficients. The modified-wing configurations produced maximum lift coefficients which exceeded those of the baseline configuration at low-speed Mach numbers (0.300 and 0.400). This benefit was related to the behavior of the wing upper surface leading-edge suction peak and the behavior of the trailing-edge pressure. At transonic Mach numbers (0.725 to 0.900), the wing modifications produced a somewhat stronger nose-down pitching moment, a slightly higher drag at low-lift levels, and a lower drag at higher lift levels.
    Keywords: AERODYNAMICS
    Type: NASA-TP-3516 , L-17360 , NAS 1.60:3516
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    Forebody vortex flow control on the F-16C using tangential slot and jet nozzle blowing (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The present experimental investigation of the effects of tangential slot and nozzle forebody blowing on the aerodynamic and stability characteristics of the F-16C configuration, for up-to-55 deg alpha and up-to-20 deg sideslip, was conducted on a 1/15th-scale model at freestream Mach = 0.4 and Re of 2.5 million/ft, for one tangential slot-nozzle location and two chordwise jet nozzle locations. Both the slot and the jet nozzles generated large yawing moments at very low blowing rates, over a wide range of alpha and sideslip angles. The centers of pressure of the side forces which generated the yawing moments due to slot and nozzle blowing were located in the region of the leading-edge extensions (LEXs); the moments may accordingly be due to the manipulation of the combined forebody and LEX flowfields.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 92-0019
    Format: text
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    NASA TECHNICAL REPORTS
  • 5
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    Wind tunnel results for a high-speed, natural laminar-flow airfoil designed for general aviation aircraft (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Two dimensional wind tunnel tests were conducted on a high speed natural laminar flow airfoil in both the Langley 6 x 28 inch Transonic Tunnel and the Langley Low Turbulence Pressure Tunnel. The test conditions consisted of Mach numbers ranging from 0.10 to 0.77 and Reynolds numbers ranging from 3 x 1 million to 11 x 1 million. The airfoil was designed for a lift coefficient of 0.20 at a Mach number of 0.70 and Reynolds number of 11 x 1 million. At these conditions, laminar flow would extend back to 50 percent chord of the upper surface and 70 percent chord of the lower surface. Low speed results were also obtained with a 0.20 chord trailing edge split flap deflected 60 deg.
    Keywords: AERODYNAMICS
    Type: NASA-TM-87602 , NAS 1.15:87602
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 6
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    The Next Generation of High-Speed Dynamic Stability Wind Tunnel Testing (Invited) (2006)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Throughout industry, accurate measurement and modeling of dynamic derivative data at high-speed conditions has been an ongoing challenge. The expansion of flight envelopes and non-conventional vehicle design has greatly increased the demand for accurate prediction and modeling of vehicle dynamic behavior. With these issues in mind, NASA Langley Research Center (LaRC) embarked on the development and shakedown of a high-speed dynamic stability test technique that addresses the longstanding problem of accurately measuring dynamic derivatives outside the low-speed regime. The new test technique was built upon legacy technology, replacing an antiquated forced oscillation system, and greatly expanding the capabilities beyond classic forced oscillation testing at both low and high speeds. The modern system is capable of providing a snapshot of dynamic behavior over a periodic cycle for varying frequencies, not just a damping derivative term at a single frequency.
    Keywords: Aircraft Stability and Control
    Type: AIAA Paper 2006-3148 , 25th AIAA Aerodynamic Measurement Technology and Ground Testing Conference; Jun 05, 2006 - Jun 08, 2006; San Francisco, CA; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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