SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS
A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 43, ISSUE 20 - OCTOBER 07, 2005
05 AIRCRAFT DESIGN, TESTING AND PERFORMANCE
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.
20050214855 NASA Glenn Research Center, Cleveland, OH, USA
New Tools Being Developed for Engine- Airframe Blade-Out Structural Simulations
Lawrence, Charles; Research and Technology 2002; March 2003; 2 pp.; In English; No Copyright; Avail.: CASI: A01, Hardcopy
One of the primary concerns of aircraft structure designers is the accurate simulation of the blade-out event. This is required for the aircraft to pass Federal Aviation Administration (FAA) certification and to ensure that the aircraft is safe for operation. Typically, the most severe blade-out occurs when a first-stage fan blade in a high-bypass gas turbine engine is released.
Structural loading results from both the impact of the blade onto the containment ring and the subsequent instantaneous unbalance of the rotating components. Reliable simulations of blade-out are required to ensure structural integrity during flight as well as to guarantee successful blade-out certification testing. The loads generated by these analyses are critical to the design teams for several components of the airplane structures including the engine, nacelle, strut, and wing, as well as the aircraft fuselage.
Currently, a collection of simulation tools is used for aircraft structural design. Detailed high-fidelity simulation tools are used to capture the structural loads resulting from blade loss, and then these loads are used as input into an overall system model that includes complete structural models of both the engines and the airframe. The detailed simulation (shown in the figure) includes the time-dependent trajectory of the lost blade and its interactions with the containment structure, and the system simulation includes the lost blade loadings and the interactions between the rotating turbomachinery and the remaining aircraft structural components. General-purpose finite element structural analysis codes are typically used, and special provisions are made to include transient effects from the blade loss and rotational effects resulting from the engine s turbomachinery.
To develop and validate these new tools with test data, the NASA Glenn Research Center has teamed with GE Aircraft Engines, Pratt & Whitney, Boeing Commercial Aircraft, Rolls-Royce, and MSC.Software. Author
Airframes; Fan Blades; Aircraft Structures; Computerized SIMulation; Finite Element Method; Rotation; Structural Analysis; Structural Design; Structural Failure
20050214860 NASA Glenn Research Center, Cleveland, OH, USA
Fan Noise Source Diagnostic Test Completed and Documented Envia, Edmane; Research and Technology 2002
Martch 2003; 3 pp.; In English; No Copyright;Avail.: CASI: A01, Hardcopy
The specially organized session offered an international forum to disseminate the results from a year long test that was conducted in 1999 in NASA Glenn Research Center s 9- by 15-Foot Low-SpeedWind Tunnel on a 22-in. scale-model turbofan bypass stage, which was designed to be representative of current aircraft engine technology. The test was a cooperative effort involving Glenn, the NASA Langley Research Center, GE Aircraft Engines, and the Boeing Company. The principal objective of the project was to study the source mechanisms of noise in a modern high-bypass-ratio turbofan engine through detailed aerodynamic and acoustic measurements. Derived from text
Acoustic Measurement; Aerodynamic Noise; Fan Blades; Turbofan Engines
20050214861 NASA Glenn Research Center, Cleveland, OH, USA, Ohio Aerospace Inst., OH, USA
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Neural Network and Regression Methods Demonstrated in the Design Optimization of a Subsonic Aircraft
Hopkins, Dale A.; Lavelle, Thomas M.; Patnaik, Surya; Research and Technology 2002; March 2003; 2 pp.; In English; No Copyright; Avail.: CASI: A01, Hardcopy
The neural network and regression methods of NASA Glenn Research Center s COMETBOARDS design optimization testbed were used to generate approximate analysis and design models for a subsonic aircraft operating at Mach 0.85 cruise speed. The analytical model is defined by nine design variables: wing aspect ratio, engine thrust, wing area, sweep angle, chord-thickness ratio, turbine temperature, pressure ratio, bypass ratio, fan pressure; and eight response parameters: weight, landing velocity, takeoff and landing field lengths, approach thrust, overall efficiency, and compressor pressure and temperature. The variables were adjusted to optimally balance the engines to the airframe.
The solution strategy included a sensitivity model and the soft analysis model. Researchers generated the sensitivity model by training the approximators to predict an optimum design. The trained neural network predicted all response variables, within 5-percent error. This was reduced to 1 percent by the regression method.
The soft analysis model was developed to replace aircraft analysis as the reanalyzer in design optimization. Soft models have been generated for a neural network method, a regression method, and a hybrid method obtained by combining the approximators. The performance of the models is graphed for aircraft weight versus thrust as well as for wing area and turbine temperature. The regression method followed the analytical solution with little error. The neural network exhibited 5-percent maximum error over all parameters.
Performance of the hybrid method was intermediate in comparison to the individual approximators. Error in the response variable is smaller than that shown in the figure because of a distortion scale factor. The overall performance of the approximators was considered to be satisfactory because aircraft analysis with NASA Langley Research Center s FLOPS (Flight Optimization System) code is a synthesis of diverse disciplines: weight estimation, aerodynamic analysis, engine cycle analysis, propulsion data interpolation, mission performance, airfield length for landing and takeoff, noise footprint, and others. Author
Design Optimization; Design Analysis; Aircraft Models; Neural Nets; Mathematical Models
20050214865 NASA Glenn Research Center, Cleveland, OH, USA
Oil-Free Turbomachinery Research Enhanced by Thrust Bearing Test Capability
Bauman, Steven W.; Research and Technology 2002; March 2003; 3 pp.; In English; No Copyright; Avail.: CASI: A01, Hardcopy
NASA Glenn Research Center s Oil-Free Turbomachinery research team is developing aircraft turbine engines that will not require an oil lubrication system. Oil systems are required today to lubricate rolling-element bearings used by the turbine and fan shafts. For the Oil-Free Turbomachinery concept, researchers combined the most advanced foil (air) bearings from industry with NASA-developed high-temperature solid lubricant technology. In 1999, the world s first Oil-Free turbocharger was demonstrated using these technologies. Now we are working with industry to demonstrate Oil-Free turbomachinery technology in a small business jet engine, the EJ-22 produced byWilliams International and developed during Glenn s recently concluded General Aviation Propulsion (GAP) program. Eliminating the oil system in this engine will make it simpler, lighter (approximately 15 percent), more reliable, and less costly to purchase and maintain. Propulsion gas turbines will place high demands on foil air bearings, especially the thrust bearings. Up until now, the Oil-Free Turbomachinery research team only had the capability to test radial, journal bearings. This research has resulted in major improvements in the bearings performance, but journal bearings are cylindrical, and can only support radial shaft loads. To counteract axial thrust loads, thrust foil bearings, which are disk shaped, are required. Since relatively little research has been conducted on thrust foil air bearings, their performance lags behind that of journal bearings. Derived from text
Turbomachinery; Thrust Bearings; Turbine Engines; Lubrication Systems; Oils
20050215039 NASA Glenn Research Center, Cleveland, OH, USA
Short Takeoff and Vertical Landing Capability Upgraded in NASA Glenn's 9- by 15-Foot Low-Speed Wind Tunnel
Stark, David E.; Research and Technology 2002; March 2003; 2 pp.; In English; No Copyright; Avail.: CASI: A01, Hardcopy
The NASA Glenn Research Center supports short takeoff and vertical landing (STOVL) tests in its 9- by 15-Foot Low SpeedWind Tunnel (9 x 15 LSWT). As part of a facility capability upgrade, a dynamic actuation system (DAS) was fabricated to enhance the STOVL testing capabilities.
The DAS serves as the mechanical interface between the 9 x 15 LSWT test section structure and the STOVL model to be tested. It provides vertical and horizontal translation of the model in the test section and maintains the model attitude (pitch, yaw, and roll) during translation. It also integrates a piping system to supply the model with exhaust and hot air to simulate the inlet suction and nozzle exhausts, respectively. Hot gas ingestion studies have been performed with the facility ground plane installed. The DAS provides vertical (ascent and descent) translation speeds of up to 48 in./s and horizontal translation speeds of up to 12 in./s. Model pitch variations of +/- 7, roll variations of +/- 5, and yaw variations of 0 to 180 deg can be accommodated and are maintained within 0.25 deg throughout the translation profile. The hot air supply, generated by the facility heaters and regulated by control valves, provides three separate temperature zones to the model for STOVL and hot gas ingestion testing. Channels along the supertube provide instrumentation paths from the model to the facility data system for data collection purposes.
The DAS is supported by the 9 x 15 LSWT test section ceiling structure. A carriage that rides on two linear rails provides for horizontal translation of the system along the test section longitudinal axis. A vertical translation assembly, consisting of a cage and supertube, is secured to the carriage. The supertube traverses vertically through the cage on a set of linear rails. Both translation axes are hydraulically actuated and provide position and velocity profile control. The lower flange on the supertube serves as the model interface to the DAS. The supertube also serves as the exhaust path to the model and supports the hot air piping on its external surfaces. The DAS is currently being assembled at the 9 15 LSWT facility. Following assembly and installation, a series of checkouts will be performed to confirm the operation of the system. Author
Vertical Landing; Attitude (Inclination); Data Systems; Inlet Nozzles; Takeoff; V/STOL Aircraft
20050215259 NASA Glenn Research Center, Cleveland, OH, USA
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TURBO-AE Code Used to Redesign the Quiet High-Speed Fan
Bakhle, Milind A.; Srivastava, Rakesh; Research and Technology 2003; May 2004; 1 pp.; In English; No Copyright; Avail.: CASI: A01, Hardcopy
The NASA/Honeywell Quiet High-Speed Fan (QHSF) was designed with aggressive goals for performance and noise reduction. During testing in NASA Glenn Research Center's 9- by 15-Foot Low-Speed Wind Tunnel, this forward-swept fan performed very well at design speed, and it also accomplished its goal of decreasing noise (6 dB measured) from the baseline fan used in current engines. However, an unexpected, severe flutter problem was encountered at part-speed conditions.
Honeywell and Glenn used the flutter analysis capability of the TURBO-AE code to redesign the QHSF. The TURBO-AE code was included in Honeywell's design cycle. During the redesign effort, more than 30 airfoil geometries were analyzed in the design-of-experiments approach and more than 600 TURBO-AE flutter analyses were performed. The redesigned QHSF II, which is predicted to be flutter-free throughout its operating range, is being fabricated and will be tested in Glenn's 9- by 15-ft wind tunnel in the near future.
Engine validation of the TURBO-AE flutter predictions for the QHSF II will be conducted on Honeywell's AS-907 advanced technology demonstrator engine in 2005. This work contributes directly to NASA's 10-year goal of reducing noise in future aircraft by 50 percent (10 dB) from current levels. It also enables aircraft engine blade rows to be checked for flutter stability during design with realistic physics modeling, thus eliminating added costs ($5 to $30 million) and delays (1 to 3 months) in engine development due to unexpected flutter vibrations. If a flutter analysis tool such as TURBO-AE had been available during the original QHSF design effort, the entire QHSF redesign may have been avoided, with an estimated saving of $2.4 million. The flutter calculations described here were performed under a contract by University of Toledo researchers in collaboration with Glenn and Honeywell researchers. Derived from text
Computer Programs; Noise Reduction; High Speed; Fans
20050215274 NASA Glenn Research Center, Cleveland, OH, USA
Subsonic Aircraft With Regression and Neural-Network Approximators Designed
Patnaik, Surya N.; Hopkins, Dale A.; Research and Technology 2003; May 2004; 3 pp.; In English; No Copyright; Avail.: CASI: A01, Hardcopy
At the NASA Glenn Research Center, NASA Langley Research Center's Flight Optimization System (FLOPS) and the design optimization testbed COMETBOARDS with regression and neural-network-analysis approximators have been coupled to obtain a preliminary aircraft design methodology. For a subsonic aircraft, the optimal design, that is the airframe-engine combination, is obtained by the simulation. The aircraft is powered by two high-bypass-ratio engines with a nominal thrust of about 35,000 lbf. It is to carry 150 passengers at a cruise speed of Mach 0.8 over a range of 3000 n mi and to operate on a 6000-ft runway.
The aircraft design utilized a neural network and a regression-approximations-based analysis tool, along with a multioptimizer cascade algorithm that uses sequential linear programming, sequential quadratic programming, the method of feasible directions, and then sequential quadratic programming again. Optimal aircraft weight versus the number of design iterations is shown. The central processing unit (CPU) time to solution is given. It is shown that the regression-method-based analyzer exhibited a smoother convergence pattern than the FLOPS code. The optimum weight obtained by the approximation technique and the FLOPS code differed by 1.3 percent. Prediction by the approximation technique exhibited no error for the aircraft wing area and turbine entry temperature, whereas it was within 2 percent for most other parameters.
Cascade strategy was required by FLOPS as well as the approximators. The regression method had a tendency to hug the data points, whereas the neural network exhibited a propensity to follow a mean path. The performance of the neural network and regression methods was considered adequate. It was at about the same level for small, standard, and large models with redundancy ratios (defined as the number of input-output pairs to the number of unknown coefficients) of 14, 28, and 57, respectively. In an SGI octane workstation (Silicon Graphics, Inc., Mountainview, CA), the regression training required a fraction of a CPU second, whereas neural network training was between 1 and 9 min, as given. For a single analysis cycle, the 3-sec CPU time required by the FLOPS code was reduced to milliseconds by the approximators. For design calculations, the time with the FLOPS code was 34 min. It was reduced to 2 sec with the regression method and to 4 min by the neural network technique. The performance of the regression and neural network methods was found to be satisfactory for the analysis and design optimization of the subsonic aircraft. Author
Approximation; Neural Nets; Subsonic Aircraft; Regression Analysis; Aircraft Design
20050215286 NASA Glenn Research Center, Cleveland, OH, USA
Design of Ultra-High-Power-Density Machine Optimized for Future Aircraft
Choi, Benjamin B.; Research and Technology 2003; May 2004; 2 pp.; In English; No Copyright; Avail.: CASI: A01, Hardcopy
The NASA Glenn Research Center's Structural Mechanics and Dynamics Branch is developing a compact, nonpolluting, bearingless electric machine with electric power supplied by fuel cells for future ‘more-electric' aircraft with specific power in the projected range of 50 hp/lb, whereas conventional electric machines generate usually 0.2 hp/lb. The use of such electric drives for propulsive fans or propellers depends on the successful development of ultra-high-power-density machines. One possible candidate for such ultra-high-power-density machines, a round-rotor synchronous machine with an engineering current density as high as 20,000 A/sq cm, was selected to investigate how much torque and power can be produced. Derived from text
Design Analysis; Mechanical Drives; Structural Analysis; Power Supplies
20050215418 NASA Glenn Research Center, Cleveland, OH, USA
NASA Glenn's Engine Components Research Lab, Cell 2B, Reactivated to Support the U.S. Army Research Laboratory T700 Engine Test
Beltran, Luis R.; Griffin, Thomas A.; Research and Technology 2003; May 2004; 2 pp.; In English; Original contains color illustrations; No Copyright; Avail.: CASI: A01, Hardcopy
The U.S. Army Vehicle Technology Directorate at the NASA Glenn Research Center has been directed by their parent command, the U.S. Army Research Laboratory (ARL), to demonstrate active stall technology in a turboshaft engine as the next step in transitioning this technology to the Army and aerospace industry. Therefore, the Vehicle Technology Directorate requested the reactivation of Glenn's Engine Components Research Lab, Cell 2B, (ECRL 2B). They wanted to test a T700 engine that had been used previously for turboshaft engine research as a partnership between the Army and NASA on small turbine engine research. ECRL 2B had been placed in standby mode in 1997. Glenn's Testing Division initiated reactivation in May 2002 to support the new research effort, and they completed reactivation and improvements in September 2003. Derived from text
Engine Design; Technology Transfer; Turboshafts
20050216398 NASA Glenn Research Center, Cleveland, OH, USA
Application of a Constant Gain Extended Kalman Filter for In-Flight Estimation of Aircraft Engine Performance Parameters
Kobayashi, Takahisa; Simon, Donald L.; Litt, Jonathan S.; September 2005; 19 pp.; In English; Turbo Expo 2005, 6-9 Jun. 2005, Reno, NV, USA; Original contains color and black and white illustrations Contract(s)/Grant(s): WBS 22-728-30-05; DA Proj. 1L1-61102-AF-20 Report No.(s): NASA/TM-2005-213865; E-15235; ARL-TR-3489; GT2005-68494; No Copyright; Avail.: CASI: A03, Hardcopy
An approach based on the Constant Gain Extended Kalman Filter (CGEKF) technique is investigated for the in-flight estimation of non-measurable performance parameters of aircraft engines. Performance parameters, such as thrust and stall margins, provide crucial information for operating an aircraft engine in a safe and efficient manner, but they cannot be directly measured during flight. A technique to accurately estimate these parameters is, therefore, essential for further enhancement of engine operation. In this paper, a CGEKF is developed by combining an on-board engine model and a single Kalman gain matrix. In order to make the on-board engine model adaptive to the real engine s performance variations due to degradation or anomalies, the CGEKF is designed with the ability to adjust its performance through the adjustment of artificial parameters called tuning parameters. With this design approach, the CGEKF can maintain accurate estimation performance when it is applied to aircraft engines at offnominal conditions. The performance of the CGEKF is evaluated in a simulation environment using numerous component degradation and fault scenarios at multiple operating conditions. Author
Kalman Filters; Aircraft Engines; Gas Turbine Engines; Aircraft Performance; Amplification
20050216530 Army Command and General Staff Coll., Fort Leavenworth, KS USA
Keeping the Dagger Sharp: A Comparison of MC-130H and MH-47E Selection and Training Methods
Powell, Matthew A.; Jun. 17, 2005; 84 pp.; In English Report No.(s): AD-A437057; No Copyright; Avail.: CASI: A05, Hardcopy
Since its inception in 1990, Air Force Special Operations Command (AFSOC) has struggled to balance its roles as both a Major Command in the US Air Force (USAF) and the air component of US Special Operations Command (USSOCOM). US code, Title 10, grants the authority to train US special operations forces to USSOCOM, however AFSOC is still required to observe USAF training rules and restrictions. This study compares the selection and training methodologies of AFSOC MC-130H aircrews and those of US Army MH-47E aircrews. It first analyzes the respective regulatory guidance and operational practices employed during assessment and selection, initial qualification training, and continuation training for each aircraft type. It then ascribes a quantitative valuing system to measure compliance with legal responsibilities. An analysis of the selection and training methodologies of baseline variants, the C-130 and CH-47, follows to highlight differences between conventional and unconventional forces. This study concludes that MC-130H selection and training has much more in common with conventional units than its unconventional counterpart, the MH-47E. In order to resolve the often conflicting responsibilities of air component of USSOCOM and USAF major command, this study then provides recommendations on how to modify MC-130H assessment and training methodologies. DTIC
Education; Helicopters; Selection; Transport Aircraft
20050217014 National War Coll., Washington, DC USA
The F-14D: A Case Study in Decision-Making
Van Cleef, Scott P.; Dec. 15, 1989; 14 pp.; In English Report No.(s): AD-A436987; No Copyright; Avail.: CASI: A03, Hardcopy
In April 1989, the new Secretary of Defense, Richard Cheney, forwarded to Congress a revised defense budget proposal for fiscal year (FY) 1990. One of the primary objectives of the new budget proposal was to establish levels of defense spending that would keep the overall budget within the Gramm-Rudman-Hollings deficit reduction guidelines. Part of the proposed defense budget was a decision to eliminate 12 new production F-14D Tomcat fighters from the Navy budget and to terminate the program. As the year progressed and Congress undertook to thrash out the final federal budget, the Senate and House split on the decision to eliminate F-14D production. The Senate favored elimination while the House voted to support the original 12 proposed aircraft. The issue was decided in a House-Senate Conference Committee. In the end, Congress did not eliminate F-14D production. Nor did it vote to support the House's proposal to produce 12. Instead, Congress voted for the production of 18 F-14D aircraft in FY 90! Though the final outcome appears absurd and is the type of story that makes Congress look incompetent, it was much more involved than it appeared and illustrates much of what goes into the decision-making process of the U.S. Government. How this decision came about is the subject of this paper. The author examines the major participants in the decision-making process as it pertained to the F-14D and attempts to draw some conclusions as to why the process worked as it did. DTIC
Contractors; Decision Making; Defense Program; Fighter Aircraft; Jet Aircraft; Procurement
20050217015 National War Coll., Washington, DC USA
The F-14 Decision and the Policy Making Process
Meyers, Robert H.; Dec. 15, 1989; 12 pp.; In English Report No.(s): AD-A436985; No Copyright; Avail.: CASI: A03, Hardcopy
Does America need more F-14 Navy fighter jets? After 5 months of debate in Congress, the question may finally be answered by a conference committee of the House and Senate members. But the future of the aircraft, assembled on Long Island by Grumman Corporation, is likely to be decided more by old-fashioned politics than by the loftier issue of national defense needs. The hottest issue in the just-concluded fiscal 1990 defense authorization conference was whether to cancel the Navy's Long Island-produced F-14D, nicknamed ‘Tomcat.' Conferees settled on a final buy of 18 jets for $1.6 billion, with the proviso that no more of the Grumman Corporation fighters would ever, ever, ever be built. ‘In my roughly 20 years involved in this, I've never seen such forceful, if not ruthless, lobbying,' John W. Warner of Virginia, ranking Republican on the Senate Armed Services Committee, griped to reporters after the conference. ‘We've nicknamed the termination clause the poison pill,' and hope it sticks.' How did the U.S. Navy arrive at a final buy of 18 new jets when the House Appropriations Committee favored 12 and the Senate favored canceling the program all together? Representative John M. Spratt (D-S.C.) stated, ‘Well, you just don't understand how we do math around here!' The decision to purchase new F-14Ds offers an interesting and somewhat representative insight into the bureaucratic process. The author starts with the background of, and current issues surrounding, the procurement of the F-14D and then takes a look at the major players -- the Department of Defense, Grumman Corporation, and the Long Island Congressional Delegation -- and how each affected the outcome of the F-14D decision. DTIC
Contractors; Decision Making; Defense Program; F-14 Aircraft; Fighter Aircraft; Jet Aircraft; Policies; Procurement
20050217050 Army Command and General Staff Coll., Fort Leavenworth, KS USA
SOF Tactical Repeater
Magness, Matthew T.; Jun. 17, 2005; 110 pp.; In English; Original contains color illustrations Report No.(s): AD-A437046; No Copyright; Avail.: CASI: A06, Hardcopy
The future of Seabasing rests with the capability to rapidly re-supply and sustain forces from strategic distances. Sealift presents one way of accomplishing this sustainment; however, it is slow. The solution for rapid long-range sustainment of a Seabase must come in the form of aircraft capable of lifting massive weights over vast distances and delivering them directly to the structure. This thesis explores the primary research question: What are the long-range, heavy lift aircraft programs that could sustain Seabasing? The question is explored by using theWisconsin 7-Step Problem-Solving Strategy: state the problem, determine the solution criteria, gather needed information, generate potential solutions, compare solutions and problem, select the solution, and prepare communications. Four concepts were identified (Lighter-than-Air, Wing-in-Ground, Advanced Theater Transport, and Seaplanes) as having the capabilities to support Seabasing. Due to the many factors associated with determining the best solution, a technique of performing a grid analysis with weighted criteria is used. The results indicate that the best types of aircraft suited to sustain a Seabase are ones that are large, joint in development and operation, can be utilized outside standard military applications, and are capable of carrying massive payloads great distances. DTIC
Seas; Military Technology; Seaplanes; Payloads
Source: NASA.
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