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  • Aircraft Design, Testing and Performance
  • 2010-2014  (29)
  • 1965-1969  (1)
  • 1950-1954  (5)
  • 1940-1944  (3)
  • 1
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    In-Flight Boundary-Layer Transition of a Large Flat Plate at Supersonic Speeds (2012)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: A flight experiment was conducted to investigate the pressure distribution, local-flow conditions, and boundary-layer transition characteristics on a large flat plate in flight at supersonic speeds up to Mach 2.00. The tests used a NASA testbed aircraft with a bottom centerline mounted test fixture. The primary objective of the test was to characterize the local flow field in preparation for future tests of a high Reynolds number natural laminar flow test article. A second objective was to determine the boundary-layer transition characteristics on the flat plate and the effectiveness of using a simplified surface coating. Boundary-layer transition was captured in both analog and digital formats using an onboard infrared imaging system. Surface pressures were measured on the surface of the flat plate. Flow field measurements near the leading edge of the test fixture revealed the local flow characteristics including downwash, sidewash, and local Mach number. Results also indicated that the simplified surface coating did not provide sufficient insulation from the metallic structure, which likely had a substantial effect on boundary-layer transition compared with that of an adiabatic surface. Cold wall conditions were predominant during the acceleration to maximum Mach number, and warm wall conditions were evident during the subsequent deceleration.
    Keywords: Aircraft Design, Testing and Performance
    Type: NASA/TM-2012-216021 , DFRC-E-DAA-TN5282
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Experimental Investigation of Spreading Characteristics of Choked Jets Expanding into Quiescent Air (1950)
    In:  CASI
    Details
    Publication Date: 2019-07-11
    Description: Investigations have been conducted to determine by means of total-pressure surveys the boundaries of single and twin jets discharging through convergent nozzles into quiescent air. The jet boundaries for the region from the nozzle outlets to a station 6 nozzle diameters downstream are presented for nozzle pressure ratios ranging from 2.5 t o 16.0 and for twin-Jet nozzle center-line spacings ranging from 1.42 to 2.50 nozzle diameters. The effects of these parameters on the interaction of twin Jets are discussed. In order to ascertain the utility of the results for other than the test conditions, the effects of jet temperature, Reynolds number, and humidity on the pressure boundaries have been briefly investigated. The result indicate that for a jet of 2.6 the pressure boundaries are slightly smaller than those of corresponding unheated jets and that the effects of Reynolds number and humidity are negligible.
    Keywords: Aircraft Design, Testing and Performance
    Type: NACA-RM-E50E03a
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    N+3 Aircraft Concept Designs and Trade Studies (2010)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: Appendices A to F present the theory behind the TASOPT methodology and code. Appendix A describes the bulk of the formulation, while Appendices B to F develop the major sub-models for the engine, fuselage drag, BLI accounting, etc.
    Keywords: Aircraft Design, Testing and Performance
    Type: NASA/CR-2010-216794/VOL2 , E-17419-2
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    N+3 Aircraft Concept Designs and Trade Studies (2010)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: MIT, Aerodyne Research, Aurora Flight Sciences, and Pratt & Whitney have collaborated to address NASA s desire to pursue revolutionary conceptual designs for a subsonic commercial transport that could enter service in the 2035 timeframe. The MIT team brings together multidisciplinary expertise and cutting-edge technologies to determine, in a rigorous and objective manner, the potential for improvements in noise, emissions, and performance for subsonic fixed wing transport aircraft. The collaboration incorporates assessment of the trade space in aerodynamics, propulsion, operations, and structures to ensure that the full spectrum of improvements is identified. Although the analysis focuses on these key areas, the team has taken a system-level approach to find the integrated solutions that offer the best balance in performance enhancements. Based on the trade space analyses and system-level assessment, two aircraft have been identified and carried through conceptual design to show both the in-depth engineering that underpins the benefits envisioned and also the technology paths that need to be followed to enable, within the next 25 years, the development of aircraft three generations ahead in capabilities from those flying today.
    Keywords: Aircraft Design, Testing and Performance
    Type: NASA/CR-2010-216794/VOL1 , E-17419-1
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 5
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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
  • 6
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    Tradespace Exploration of Distributed Propulsors for Advanced On-Demand Mobility Concepts (2014)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Combustion-based sources of shaft power tend to significantly penalize distributed propulsion concepts, but electric motors represent an opportunity to advance the use of integrated distributed propulsion on an aircraft. This enables use of propellers in nontraditional, non-thrust-centric applications, including wing lift augmentation, through propeller slipstream acceleration from distributed leading edge propellers, as well as wingtip cruise propulsors. Developing propellers for these applications challenges long-held constraints within propeller design, such as the notion of optimizing for maximum propulsive efficiency, or the use of constant-speed propellers for high-performance aircraft. This paper explores the design space of fixed-pitch propellers for use as (1) lift augmentation when distributed about a wing's leading edge, and (2) as fixed-pitch cruise propellers with significant thrust at reduced tip speeds for takeoff. A methodology is developed for evaluating the high-level trades for these types of propellers and is applied to the exploration of a NASA Distributed Electric Propulsion concept. The results show that the leading edge propellers have very high solidity and pitch well outside of the empirical database, and that the cruise propellers can be operated over a wide RPM range to ensure that thrust can still be produced at takeoff without the need for a pitch change mechanism. To minimize noise exposure to observers on the ground, both the leading edge and cruise propellers are designed for low tip-speed operation during takeoff, climb, and approach.
    Keywords: Aircraft Design, Testing and Performance
    Type: AIAA Paper-2014-2850 , NF1676L-17830 , AVIATION 2014 (The Aviation and Aeronautics Forum and Exposition); Jun 16, 2014 - Jun 20, 2014; Atlanta, GA; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 7
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    Rotary-Wing Relevant Compressor Aero Research and Technology Development Activities at Glenn Research Center (2012)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Technical challenges of compressors for future rotorcraft engines are driven by engine-level and component-level requirements. Cycle analyses are used to highlight the engine-level challenges for 3000, 7500, and 12000 SHP-class engines, which include retention of performance and stability margin at low corrected flows, and matching compressor type, axial-flow or centrifugal, to the low corrected flows and high temperatures in the aft stages. At the component level: power-to-weight and efficiency requirements impel designs with lower inherent aerodynamic stability margin; and, optimum engine overall pressure ratios lead to small blade heights and the associated challenges of scale, particularly increased clearance-to-span ratios. The technical challenges associated with the aerodynamics of low corrected flows and stability management impel the compressor aero research and development efforts reviewed herein. These activities include development of simple models for clearance sensitivities to improve cycle calculations, full-annulus, unsteady Navier-Stokes simulations used to elucidate stall, its inception, and the physics of stall control by discrete tip-injection, development of an actuator-duct-based model for rapid simulation of nonaxisymmetric flow fields (e.g., due inlet circumferential distortion), advanced centrifugal compressor stage development and experimentation, and application of stall control in a T700 engine.
    Keywords: Aircraft Design, Testing and Performance
    Type: NASA/TM-2012-217280 , ARL-TR-4757 , E-18035 , 65th Annual Forum and Technology Display (AHS Forum 65); May 27, 2009 - May 29, 2009; Grapevine, TX; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 8
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    Initial Assessment of Open Rotor Propulsion Applied to an Advanced Single-Aisle Aircraft (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Application of high speed, advanced turboprops, or propfans, to subsonic transport aircraft received significant attention and research in the 1970s and 1980s when fuel efficiency was the driving focus of aeronautical research. Recent volatility in fuel prices and concern for aviation s environmental impact have renewed interest in unducted, open rotor propulsion, and revived research by NASA and a number of engine manufacturers. Unfortunately, in the two decades that have passed since open rotor concepts were thoroughly investigated, NASA has lost experience and expertise in this technology area. This paper describes initial efforts to re-establish NASA s capability to assess aircraft designs with open rotor propulsion. Specifically, methodologies for aircraft-level sizing, performance analysis, and system-level noise analysis are described. Propulsion modeling techniques have been described in a previous paper. Initial results from application of these methods to an advanced single-aisle aircraft using open rotor engines based on historical blade designs are presented. These results indicate open rotor engines have the potential to provide large reductions in fuel consumption and emissions. Initial noise analysis indicates that current noise regulations can be met with old blade designs and modern, noiseoptimized blade designs are expected to result in even lower noise levels. Although an initial capability has been established and initial results obtained, additional development work is necessary to make NASA s open rotor system analysis capability on par with existing turbofan analysis capabilities.
    Keywords: Aircraft Design, Testing and Performance
    Type: NF1676L-12112 , 11th AIAA Aviation Technology, Integration, and Operations (ATIO) Conference; Sep 20, 2011 - Sep 22, 2011; Virginia Beach, VA; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 9
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    A Comparative Analysis of Two Full-Scale MD-500 Helicopter Crash Tests (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Two full scale crash tests were conducted on a small MD-500 helicopter at NASA Langley Research Center fs Landing and Impact Research Facility. One of the objectives of this test series was to compare airframe impact response and occupant injury data between a test which outfitted the airframe with an external composite passive energy absorbing honeycomb and a test which had no energy absorbing features. In both tests, the nominal impact velocity conditions were 7.92 m/sec (26 ft/sec) vertical and 12.2 m/sec (40 ft/sec) horizontal, and the test article weighed approximately 1315 kg (2900 lbs). Airframe instrumentation included accelerometers and strain gages. Four Anthropomorphic Test Devices were also onboard; three of which were standard Hybrid II and III, while the fourth was a specialized torso. The test which contained the energy absorbing honeycomb showed vertical impact acceleration loads of approximately 15 g, low risk for occupant injury probability, and minimal airframe damage. These results were contrasted with the test conducted without the energy absorbing honeycomb. The test results showed airframe accelerations of approximately 40 g in the vertical direction, high risk for injury probability in the occupants, and substantial airframe damage.
    Keywords: Aircraft Design, Testing and Performance
    Type: NF1676L-11537 , SEM Annual Conference and Exposition on Experimental and Applied Mechanics; Jun 13, 2011 - Jun 15, 2011; Uncasville, CT; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 10
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    Overview of Lightweight Structures for Rotorcraft Engines and Drivetrains (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This is an overview presentation of research being performed in the Advanced Materials Task within the NASA Subsonic Rotary Wing Project. This research is focused on technology areas that address both national goals and project goals for advanced rotorcraft. Specific technology areas discussed are: (1) high temperature materials for advanced turbines in turboshaft engines; (2) polymer matrix composites for lightweight drive system components; (3) lightweight structure approaches for noise and vibration control; and (4) an advanced metal alloy for lighter weight bearings and more reliable mechanical components. An overview of the technology in each area is discussed, and recent accomplishments are presented.
    Keywords: Aircraft Design, Testing and Performance
    Type: E-17741 , NASA Fundamental Aeronautics 2011 Technical Conference; Mar 15, 2011 - Mar 17, 2011; Cleveland, OH; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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