SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS
A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 43, ISSUE 13 - JULY 1, 2005
05 AIRCRAFT DESIGN, TESTING AND PERFORMANCE, PART II
Includes all stages of design of aircraft and aircraft structures and systems.
Also includes aircraft testing, performance, and evaluation, and aircraft and flight simulation technology.
For related information see also 18 Spacecraft Design, Testing and Performance; and 39 Structural Mechanics.
For land transportation vehicles see 85 Technology Utilization and Surface Transportation.
20050177920 NASA Lewis Research Center, Cleveland, OH, USA
High Speed Research: Propulsion Project Accomplishments
Shaw, Robert J.; Research and Technology 1997; April 1998; 2 pp.; In English; No Copyright; Avail: Other Sources; Abstract Only
This past year has been one of great accomplishment for the propulsion element of NASA’s High Speed Research (HSR) Program. The HSR Program is a NASA/industry partnership to develop the high-risk/high-payoff airframe and propulsion technologies applicable to a second-generation supersonic commercial transport, or High Speed Civil Transport (HSCT). The propulsion element, which also involves industry partners, is managed by the NASA Lewis Research Center. These technologies will contribute greatly to U.S. industry’s ability to make an informed product launch decision for an HSCT vehicle.
Specific NASA Lewis accomplishments in 1997 include:
1. Small-scale combustor sector tests conducted in Lewis’ Engine Research Building contributed to the evolution of approaches to developing a combustor with ultralow NOx emissions.
2. Components were tested in Lewis’ CE-9 facility (in Lewis’ Engine Research Building) to assess the performance of candidate ceramic matrix composite (CMC) materials in this realistic combustion environment. Test results were promising, and acceptable levels of structural durability were demonstrated for the ceramic matrix composite material tested. Ceramic matrix composites continue to show great promise for use in HSCT combustor liners.
3. Engine emissions tests in Lewis’ Propulsion Systems Laboratory provided insight into other classes of emissions (e.g., particulates and aerosols) which will be important to control in HSCT propulsion system designs.
4. Small-scale nozzle tests conducted in Lewis’ Aero-Acoustic Propulsion Laboratory are contributing to the design of a low-noise, high-performance mixer/ejector nozzle configuration for HSCT engines.
Over 18,000 hours of durability testing were completed in Lewis’ materials laboratories to evaluate superalloy and g-titanium aluminide performance for HSCT nozzle applications. A two-dimensional supersonic inlet concept was tested in Lewis’ 10- by 10-Foot Supersonic Wind Tunnel. The extensive database and the knowledge gained contributed to the selection of a two-dimensional inlet as the preferred inlet concept for the HSR Program. Author
Airframes; Ceramic Matrix Composites; Exhaust Emission; Low Noise; Propulsion System Configurations
20050180248 State Univ. of New York, Binghamton, NY, USA, Unisys Corp., Hampton, VA, USA
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Motion Cueing Algorithm Development: Piloted Performance Testing of the Cueing Algorithms
Houck, Jacob A., Technical Monitor; Telban, Robert J.; Cardullo, Frank M.; Kelly, Lon C.; May 2005; 102 pp.; In English; Original contains color and black and white illustrations; Contract(s)/Grant(s): NASA Order L-70823-D; WU 23-090-70-10; Report No.(s): NASA/CR-2005-213748; No Copyright; Avail: CASI; A06, Hardcopy
The relative effectiveness in simulating aircraft maneuvers with both current and newly developed motion cueing algorithms was assessed with an eleven-subject piloted performance evaluation conducted on the NASA Langley Visual Motion Simulator (VMS). In addition to the current NASA adaptive algorithm, two new cueing algorithms were evaluated: the optimal algorithm and the nonlinear algorithm. The test maneuvers included a straight-in approach with a rotating wind vector, an offset approach with severe turbulence and an on/off lateral gust that occurs as the aircraft approaches the run threshold, and a takeoff both with and without engine failure after liftoff. The maneuvers were executed with each cueing algorithm with added visual display delay conditions ranging from zero to 200 msec. Two methods, the quasi-objective NASA Task Load Index (TLX), and power spectral density analysis of pilot control, were used to assess pilot workload. Piloted performance parameters for the approach maneuvers, the vertical velocity upon touchdown and the runway touchdown position, were also analyzed but did not show any noticeable difference among the cueing algorithms. TLX analysis reveals, in most cases, less workload and variation among pilots with the nonlinear algorithm. Control input analysis shows pilot-induced oscillations on a straight-in approach were less prevalent compared to the optimal algorithm. The augmented turbulence cues increased workload on an offset approach that the pilots deemed more realistic compared to the NASA adaptive algorithm. The takeoff with engine failure showed the least roll activity for the nonlinear algorithm, with the least rudder pedal activity for the optimal algorithm. Author
Algorithms; Performance Tests; Pilot Induced Oscillation; Spectrum Analysis; Motion Simulators
20050180846 NASA Lewis Research Center, Cleveland, OH, USA
Design Process for High Speed Civil Transport Aircraft Improved by Neural Network and Regression Methods
Hopkins, Dale A.; Research and Technology 1997; April 1998; 2 pp.; In English; No Copyright; Avail: CASI; A01, Hardcopy
A key challenge in designing the new High Speed Civil Transport (HSCT) aircraft is determining a good match between the airframe and engine. Multidisciplinary design optimization can be used to solve the problem by adjusting parameters of both the engine and the airframe. Earlier, an example problem was presented of an HSCT aircraft with four mixed-flow turbofan engines and a baseline mission to carry 305 passengers 5000 nautical miles at a cruise speed of Mach 2.4. The problem was solved by coupling NASA Lewis Research Center’s design optimization testbed (COMETBOARDS) with NASA Langley Research Center’s Flight Optimization System (FLOPS). The computing time expended in solving the problem was substantial, and the instability of the FLOPS analyzer at certain design points caused difficulties. In an attempt to alleviate both of these limitations, we explored the use of two approximation concepts in the design optimization process. The two concepts, which are based on neural network and linear regression approximation, provide the reanalysis capability and design sensitivity analysis information required for the optimization process. The HSCT aircraft optimization problem was solved by using three alternate approaches; that is, the original FLOPS analyzer and two approximate (derived) analyzers. The approximate analyzers were calibrated and used in three different ranges of the design variables; narrow (interpolated), standard, and wide (extrapolated). Author
Aircraft Design; Multidisciplinary Design Optimization; Regression Analysis; Neural Nets
20050180847 NASA Lewis Research Center, Cleveland, OH, USA
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Procedure Developed for Ballistic Impact Testing of Composite Fan Containment Concepts
Pereira, J. Michael; Melis, Matthew E.; Research and Technology 1997; April 1998; 3 pp.; In English; No Copyright; Avail: CASI; A01, Hardcopy
The fan-containment system in a jet engine is designed to prevent a fan blade from penetrating the engine case in the event that the blade or a portion of the blade separates from the rotor during operation. Usually, these systems consist of a thick metal case that is strong enough to survive such an impact. Other systems consist of a dry aramid fabric wrapped around a relatively thin metal case. In large turbofan engines, metal-containment systems can weigh well over 300 kg, and there is a strong impetus to reduce their weight. As a result, the NASA Lewis Research Center is involved in an effort to develop polymer matrix composite (PMC) fan-containment systems to reduce the weight and cost while maintaining the high levels of safety associated with current systems. Under a Space Act Agreement with AlliedSignal Aircraft Engines, a new ballistic impact test procedure has been developed to quantitatively evaluate the performance of polymer matrix composite systems. Derived from text
Impact Tests; Terminal Ballistics; Polymer Matrix Composites; Aircraft Construction Materials
20050181413 NASA Lewis Research Center, Cleveland, OH, USA
Liquid Motion Experiment Flown on STS-84
Dalton, Penni J.; Research and Technology 1997; April 1998; 3 pp.; In English; No Copyright; Avail: CASI; A01, Hardcopy
During some part or all of each mission, about half of all scientific and commercial spacecraft will spin. For example, commercial spacecraft are made to spin during the transfer maneuver from low Earth orbit to the mission orbit to obtain gyroscopic stiffness. Many spacecraft spin continuously in orbit for the same reason. Other reasons for spinning include controlling the location of liquid propellants within their tanks and distributing solar heat loads. Although spinning has many benefits, it also creates problems because of the unavoidable wobble motion that accompanies spinning. Wobbling makes the spacecraft’s flexible components oscillate. The energy dissipated by the internal friction of these components causes the wobbling amplitude to increase continually until, at some point, the attitude control thrusters must be fired to bring the spacecraft’s amplitude back to an acceptable level. Derived from text
Attitude Control; Liquid Rocket Propellants; Loads (Forces); Stiffness; Spin Dynamics
20050181414 NASA Lewis Research Center, Cleveland, OH, USA
Closed Cycle Engine Program Used in Solar Dynamic Power Testing Effort
Ensworth, Clint B., III; McKissock, David B.; Research and Technology 1997; April 1998; 2 pp.; In English; No Copyright; Avail: CASI; A01, Hardcopy
NASA Lewis Research Center is testing the world’s first integrated solar dynamic power system in a simulated space environment. This system converts solar thermal energy into electrical energy by using a closed-cycle gas turbine and alternator. A NASA-developed analysis code called the Closed Cycle Engine Program (CCEP) has been used for both pretest predictions and post-test analysis of system performance. The solar dynamic power system has a reflective concentrator that focuses solar thermal energy into a cavity receiver. The receiver is a heat exchanger that transfers the thermal power to a working fluid, an inert gas mixture of helium and xenon. The receiver also uses a phase-change material to store the thermal energy so that the system can continue producing power when there is no solar input power, such as when an Earth-orbiting satellite is in eclipse. The system uses a recuperated closed Brayton cycle to convert thermal power to mechanical power. Heated gas from the receiver expands through a turbine that turns an alternator and a compressor. The system also includes a gas cooler and a radiator, which reject waste cycle heat, and a recuperator, a gas-to-gas heat exchanger that improves cycle efficiency by recovering thermal energy. Derived from text
Brayton Cycle; Closed Cycles; Compressors; Dynamic Tests; Gas Turbines; Solar Energy
20050181961 NASA Lewis Research Center, Cleveland, OH, USA
NASA Lewis Helps Company With New Single-Engine Business Turbojet
Research and Technology 1997; April 1998; 2 pp.; In English; No Copyright; Avail: CASI; A01, Hardcopy
Century Aerospace Corporation, a small company in Albuquerque, New Mexico, is developing a six-seat aircraft powered by a single turbofan engine for general aviation. The company had completed a preliminary design of the jet but needed analyses and testing to proceed with detailed design and subsequent fabrication of a prototype aircraft. NASA Lewis Research Center used computational fluid dynamics (CFD) analyses to ferret out areas of excessive curvature in the inlet where separation might occur. A preliminary look at the results indicated very good inlet performance; and additional calculations, performed with vortex generators installed in the inlet, led to even better results. When it was initially determined that the airflow distortion pattern at the compressor face fell outside of the limits set by the engine manufacturer, the Lewis team studied possible solutions, selected the best, and provided recommendations. CFD results for the inlet system were so good that wind tunnel tests were unnecessary. Derived from text
Computational Fluid Dynamics; Turbofan Engines; Aircraft Design; General Aviation Aircraft
20050182009 NASA Lewis Research Center, Cleveland, OH, USA
Neural Network and Regression Approximations Used in Aircraft Design
Patnaik, Surya N.; Hopkins, Dale A.; Lavelle, Thomas M.; Research and Technology 1998; April 1999; 2 pp.; In English; No Copyright; Avail: CASI; A01, Hardcopy
NASA Lewis Research Center’s CometBoards Test Bed was used to create regression and neural network models for a High-Speed Civil Transport (HSCT) aircraft. Both approximation models that replaced the actual analysis tool predicted the aircraft response in a trivial computational effort. The models allow engineers to quickly study the effects of design variables on constraint and objective values for a given aircraft configuration. For example, an engineer can change the engine size by 1000 pounds of thrust and quickly see how this change affects all the output values without rerunning the entire simulation. In addition, an engineer can change a constraint and use the approximation models to quickly reoptimize the configuration. Generating the neural network and the regression models is a time-consuming process, but this exercise has to be carried out only once. Furthermore, an automated process can reduce calculations substantially. Derived from text
Aircraft Configurations; Aircraft Performance; Transport Aircraft
20050182015 Toensmeier (Patrick A.), Arlington, VA, USA
Radical Departure: Morphing structures could bring multi-role capabilities to next-generation aircraft
Toensmeier, Patrick A.; Aviation Week & Space Technology; May 23, 2005; ISSN 0005-2175; Volume 162, No. 21, pp. 72-73; In English; Copyright; Avail: Other Sources
Two prototypes of a wing that changes shape radically in flight will undergo structural and aerodynamic testing in July and August by the Defense Advanced Research Projects Agency (Darpa). These ‘morphing’ wings-the next step beyond traditional variable-geometry wings that change position mechanically are in development by Lockheed Martin and Hypercomp/NextGen as part of Darpa s Morphing Aircraft Structures (MAS) program. The objective of the program is to develop technology for a new generation of military aircraft that achieves significant multi-role capabilities through the use of morphing components. Derived from text
Wings; Aerodynamic Characteristics; Shapes
20050182109 NASA Langley Research Center, Hampton, VA, USA
Scramjet Development Tests Supporting the Mach 10 Flight of the X-43
Rogers, R. C.; Shih, A. T.; Hass, N. E.; [2005]; 11 pp.; In English;
13th AIAA/CIRA International Space Planes and Hypersonic Systems Technologies Conference, 16-20 May 2005, Capua, Italy; Contract(s)/Grant(s): 23-745-30-00
Report No.(s): AIAA Paper 2005-3351; No Copyright; Avail: CASI; A03, Hardcopy
The Hyper-X Project s successful third flight of the X-43 at near Mach 10 in 2004 proved the potential for airbreathing propulsion at hypersonic speeds. The engine flowpath used in the X-43 research vehicle was developed and evaluated in a systematic series of ground tests in the NASA HyPulse Shock Tunnel at conditions duplicating Mach 10 flight using a full scale height, partial width engine model of the flight engine. Tests were conducted over a range of equivalence ratios from 0.8 to 1.6 using hydrogen and a mixture of two-percent silane in hydrogen fuels. Silane gas was used as an ignition aid during the short duration of the pulse facility tests. Variation of the engine inflow conditions, pressure, temperature, and Mach number, were parametrically varied during the test entries to broaden the database over the expected uncertainty in the flight conditions. A review of the ground test technique and comparisons of the ground test pressures along with selected flight data are presented. Author
Performance Tests; X-43 Vehicle; Air Breathing Engines; Ground Tests; Hypersonic Speed; Supersonic Combustion Ramjet Engines
20050182117 NASA Ames Research Center, Moffett Field, CA, USA, Maryland Univ., College Park, MD, USA, NASA Ames Research Center, Moffett Field, CA, USA
Performance of Swashplateless Ultralight Helicopter Rotor with Trailing-edge Flaps for Primary Flight Control
Shen, Jin-Wei; Chopra, Inderjit; [2003]; 1 pp.; In English; American Helicopter Society Annual Forum, May 2003, Phoenix, AZ, USA; Copyright; Avail: CASI; A01, Hardcopy
The objective of present study is to evaluate the rotor performance, trailing-edge deflections and actuation requirement of a helicopter rotor with trailing-edge flap system for primary flight control. The swashplateless design is implemented by modifying a two-bladed teetering rotor of an production ultralight helicopter through the use of plain flaps on the blades, and by replacing the pitch link to fixed system control system assembly with a root spring. A comprehensive rotorcraft analysis based on UMARC is carried out to obtain the results for both the swashplateless and a conventional baseline rotor configuration. The predictions show swashplateless configuration achieve superior performance than the conventional rotor attributed from reduction of parasite drag by eliminating swashplate mechanic system. It is indicated that optimal selection of blade pitch index angle, flap location, length, and chord ratio reduces flap deflections and actuation requirements, however, has virtually no effect on rotor performance. Author
Rotary Wing Aircraft; Trailing Edge Flaps; Helicopter Tail Rotors; Helicopter Performance
20050182126 NASA Langley Research Center, Hampton, VA, USA
Blended-Wing-Body (BWB) Fuselage Structural Design for Weight Reduction
Mukhopadhyay, V.; [2005]; 9 pp.; In English; 46th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference, 18-21 Apr. 2005, Austin, TX, USA; Original contains color illustrations; Report No.(s): AIAA Paper 2005-2349; No Copyright; Avail: CASI; A02, Hardcopy
Structural analysis and design of efficient pressurized fuselage configurations for the advanced Blended-Wing-Body (BWB) flight vehicle is a challenging problem. Unlike a conventional cylindrical pressurized fuselage, stress level in a box type BWB fuselage is an order of magnitude higher, because internal pressure primarily results in bending stress instead of skin-membrane stress. In addition, resulting deformation of aerodynamic surface could significantly affect performance advantages provided by lifting body. The pressurized composite conformal multi-lobe tanks of X-33 type space vehicle also suffered from similar problem.
In the earlier BWB design studies, Vaulted Ribbed Shell (VLRS), Flat Ribbed Shell (FRS); Vaulted shell Honeycomb Core (VLHC) and Flat sandwich shell Honeycomb Core (FLHC) concepts were studied. The flat and vaulted ribbed shell concepts were found most efficient. In a recent study, a set of composite sandwich panel and cross-ribbed panel were analyzed. Optimal values of rib and skin thickness, rib spacing, and panel depth were obtained for minimal weight under stress and buckling constraints. In addition, a set of efficient multi-bubble fuselage (MBF) configuration concept was developed. The special geometric configuration of this concept allows for balancing internal cabin pressure load efficiently, through membrane stress in inner-stiffened shell and inter-cabin walls, while the outer-ribbed shell prevents buckling due to external resultant compressive loads.
The initial results from these approximate finite element analyses indicate progressively lower maximum stresses and deflections compared to the earlier study. However, a relative comparison of the FEM weight per unit floor area of the segment unit indicates that the unit weights are still relatively higher that the conventional B777 type cylindrical or A380 type elliptic fuselage design. Due to the manufacturing concern associated with multi-bubble fuselage, a Y braced box-type fuselage alternative with special resin-film injected (RFI) stitched carbon composite with foam-core was designed by Boeing under a NASA research contract for the 480 passenger version. It is shown that this configuration can be improved to a modified multi-bubble fuselage which has better stress distribution, for same material and dimension. Author
Blended-Wing-Body Configurations; Fuselages; Structural Design; Weight Reduction
Source: NASA.
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