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At least 739 records · Page 41
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NASA NTRS2015

Green Propulsion Technologies for Advanced Air Transports

Air transportation is critical to U.S. and Global economic vitality. However, energy and climate issues challenge aviation's ability to be sustainable in the long term. Aviation must dramatically reduce fuel use and related emissions. Energy costs to U.S. airlines nearly tripled between 1995 and 2011, and continue to be the highest percentage of operating costs. The NASA Advanced Air Transports Technology Project addresses the comprehensive challenge of enabling revolutionary energy efficiency improvements in subsonic transport aircraft combined with dramatic reductions in harmful emissions and perceived noise to facilitate sustained growth of the air transportation system. Advanced technologies and the development of unconventional aircraft systems offer the potential to achieve these improvements. The presentation will highlight the NASA vision of revolutionary systems and propulsion technologies needed to achieve these challenging goals. Specifically, the primary focus is on the N+3 generation; that is, vehicles that are three generations beyond the current state of the art, requiring mature technology solutions in the 2025-30 timeframe.

Del Rosario, Rubén↗
NASA NTRS2015

Green Propulsion Technologies for Advanced Air Transports

Air transportation is critical to U.S. and Global economic vitality. However, energy and climate issues challenge aviations ability to be sustainable in the long term. Aviation must dramatically reduce fuel use and related emissions. Energy costs to U.S. airlines nearly tripled between 1995 and 2011, and continue to be the highest percentage of operating costs. The NASA Advanced Air Transports Technology Project addresses the comprehensive challenge of enabling revolutionary energy efficiency improvements in subsonic transport aircraft combined with dramatic reductions in harmful emissions and perceived noise to facilitate sustained growth of the air transportation system. Advanced technologies and the development of unconventional aircraft systems offer the potential to achieve these improvements. The presentation will highlight the NASA vision of revolutionary systems and propulsion technologies needed to achieve these challenging goals. Specifically, the primary focus is on the N+3 generation; that is, vehicles that are three generations beyond the current state of the art, requiring mature technology solutions in the 2025-30 timeframe, which are envisioned as being powered by Hybrid Electric Propulsion Systems.

Hybrid Electric↗
NASA NTRSDate not supplied

NASA Electrified Aircraft Propulsion Control

Demonstrate technologies for practical vehicle-level integration of high-power (1MW+) electrified aircraft propulsion systems with advanced airframe systems for initial applications to small transport aircraft.

Electrified Aircraft Propulsion↗
NASA NTRS1977

The aircraft energy efficiency active controls technology program

Broad outlines of the NASA Aircraft Energy Efficiency Program for expediting the application of active controls technology to civil transport aircraft are presented. Advances in propulsion and airframe technology to cut down on fuel consumption and fuel costs, a program for an energy-efficient transport, and integrated analysis and design technology in aerodynamics, structures, and active controls are envisaged. Fault-tolerant computer systems and fault-tolerant flight control system architectures are under study. Contracts with leading manufacturers for research and development work on wing-tip extensions and winglets for the B-747, a wing load alleviation system, elastic mode suppression, maneuver-load control, and gust alleviation are mentioned.

Hood, R. V., Jr.↗
NASA NTRS1974

Preliminary measurement of the airframe noise from an F-106B delta wing aircraft at low flyover speeds

To establish a realistic lower limit for the noise level of advanced supersonic transport aircraft will require knowledge concerning the amount of noise generated by the airframe itself as it moves through the air. The airframe noise level of an F-106B aircraft was determined and was compared to that predicted from an existing empirical relationship. The data were obtained from flyover and static tests conducted to determine the background noise level of the F-106B aircraft. Preliminary results indicate that the spectrum associated with airframe noise was broadband and peaked at a frequency of about 570 hertz. An existing empirical method successfully predicted the frequency where the spectrum peaked. However, the predicted OASPL value of 105 db was considerably greater than the measures value of 83 db.

Burley, R. R.↗
NASA NTRS1974

Flight-path and airspeed control during landing approach for powered-lift aircraft

Manual control of flight path and airspeed during landing approach has been investigated for powered-lift transport aircraft. An analysis was conducted to identify the behavior of the aircraft which would be potentially significant to the pilot controlling flight path and airspeed during the approach. The response characteristics found to describe the aircraft behavior were (1) the initial flight-path response and flight-path overshoot for a step change in thrust, (2) the steady-state coupling of flight path and airspeed for a step change in thrust, and (3) the sensitivity of airspeed to changes in pitch attitude. The significance of these response characteristics was evaluated by pilots on a large-motion, ground-based simulator at Ames Research Center. Coupling between flight path and airspeed was considered by the pilot to be the dominant influence on handling qualities for the approach task. Results are compared with data obtained from flight tests of three existing powered-lift V/STOL aircraft.

Franklin, J. A.↗
NASA NTRS1988

The Horizon: A blended wing aircraft configuration design project, volume 3

The results of a study to design a High-Speed Civilian Transport (HSCT) using the blended wing-body configuration are presented. The HSCT is a Mach 2 to 5 transport aircraft designed to compete with current commercial aircraft. The subjects discussed are sizing, configuration, aerodynamics, stability and control, propulsion, performance, structures and pollution effects.

Keidel, Paul↗
NASA NTRS2016

Mission Analysis and Aircraft Sizing of a Hybrid-Electric Regional Aircraft

The purpose of this study was to explore advanced airframe and propulsion technologies for a small regional transport aircraft concept (approximately 50 passengers), with the goal of creating a conceptual design that delivers significant cost and performance advantages over current aircraft in that class. In turn, this could encourage airlines to open up new markets, reestablish service at smaller airports, and increase mobility and connectivity for all passengers. To meet these study goals, hybrid-electric propulsion was analyzed as the primary enabling technology. The advanced regional aircraft is analyzed with four levels of electrification, 0 percent electric with 100 percent conventional, 25 percent electric with 75 percent conventional, 50 percent electric with 50 percent conventional, and 75 percent electric with 25 percent conventional for comparison purposes. Engine models were developed to represent projected future turboprop engine performance with advanced technology and estimates of the engine weights and flowpath dimensions were developed. A low-order multi-disciplinary optimization (MDO) environment was created that could capture the unique features of parallel hybrid-electric aircraft. It is determined that at the size and range of the advanced turboprop: The battery specific energy must be 750 watt-hours per kilogram or greater for the total energy to be less than for a conventional aircraft. A hybrid vehicle would likely not be economically feasible with a battery specific energy of 500 or 750 watt-hours per kilogram based on the higher gross weight, operating empty weight, and energy costs compared to a conventional turboprop. The battery specific energy would need to reach 1000 watt-hours per kilogram by 2030 to make the electrification of its propulsion an economically feasible option. A shorter range and/or an altered propulsion-airframe integration could provide more favorable results.

Antcliff, Kevin R.↗
NASA NTRS1986

Pilot interface with fly by wire control systems

Aircraft designers are rapidly moving toward full fly by wire control systems for transport aircraft. Aside from pilot interface considerations such as location of the control input device and its basic design such as side stick, there appears to be a desire to change the fundamental way in which a pilot applies manual control. A typical design would have the lowest order of manual control be a control wheel steering mode in which the pilot is controlling an autopilot. This deprives the pilot of the tactile sense of angle of attack which is inherent in present aircraft by virtue of certification requirements for static longitudinal stability whereby a pilot must either force the aircraft away from its trim angle of attack or trim to a new angle of attack. Whether or not an aircraft actually has positive stability, it can be made to feel to a pilot as though it does by artificial feel. Artificial feel systems which interpret pilot input as pitch rate or G rate with automatic trim have proven useful in certain military combat maneuvers, but their transposition to other more normal types of manual control may not be justified.

Melvin, W. W.↗
NASA NTRS1989

Effects of lightning on operations of aerospace vehicles

Traditionally, aircraft lightning strikes were a major aviation safety issue. However, the increasing use of composite materials and the use of digital avionics for flight critical systems will require that more specific lightning protection measures be incorporated in the design of such aircraft in order to maintain the excellent lightning safety record presently enjoyed by transport aircraft. In addition, several recent lightning mishaps, most notably the loss of the Atlas/Centaur-67 vehicle at Cape Canaveral Air Force Station, Florida in March 1987, have shown the susceptibility of aircraft and launch vehicles to the phenomenon of vehicle-triggered lightning. The recent findings of the NASA Storm Hazards Program were reviewed as they pertain to the atmospheric conditions conducive to aircraft lightning strikes. These data are then compared to recent summaries of lightning strikes to operational aircraft fleets. Finally, the new launch commit criteria for triggered lightning being used by NASA and the U.S. Defense Department are summarized. The NASA Research data show that the greatest probability of a direct strike in a thunderstorm occurs at ambient temperatures of about -40 C. Relative precipitation and turbulence levels were characterized as negligible to light for these conditions. However, operational fleet data have shown that most aircraft lightning strikes in routine operations occur at temperatures near the freezing level in non-cumulonimbus clouds. The non-thunderstorm environment was not the subject of dedicated airborne lightning research.

Fisher, Bruce D.↗
NASA NTRS1990

A review of the analytical simulation of aircraft crash dynamics

A large number of full scale tests of general aviation aircraft, helicopters, and one unique air-to-ground controlled impact of a transport aircraft were performed. Additionally, research was also conducted on seat dynamic performance, load-limiting seats, load limiting subfloor designs, and emergency-locator-transmitters (ELTs). Computer programs were developed to provide designers with methods for predicting accelerations, velocities, and displacements of collapsing structure and for estimating the human response to crash loads. The results of full scale aircraft and component tests were used to verify and guide the development of analytical simulation tools and to demonstrate impact load attenuating concepts. Analytical simulation of metal and composite aircraft crash dynamics are addressed. Finite element models are examined to determine their degree of corroboration by experimental data and to reveal deficiencies requiring further development.

Fasanella, Edwin L.↗
NASA NTRS2001

Application of Mobile-ip to Space and Aeronautical Networks

The National Aeronautics and Space Administration (NASA) is interested in applying mobile Internet protocol (mobile-ip) technologies to its space and aeronautics programs. In particular, mobile-ip will play a major role in the Advanced Aeronautic Transportation Technology (AAT-F), the Weather Information Communication (WINCOMM), and the Small Aircraft Transportation System (SATS) aeronautics programs. This paper describes mobile-ip and mobile routers--in particular, the features, capabilities, and initial performance of the mobile router are presented. The application of mobile-router technology to NASA's space and aeronautics programs is also discussed.

Leung, Kent↗
NASA NTRSDate not supplied

SUbsonic Single Aft eNgine (SUSAN) Electrofan: An Advanced Hybrid Electric Concept for Future Single-Aisle Aircraft

Address the aviation industry’s goal of achieving net-zero carbon emissions by 2050. Design an aircraft concept that can significantly reduce fuel burn and emissions in large regional transport aircraft carrying up to 180 passengers. Retain speed, size, and range in current commercial aircraft and utilize existing airport infrastructure and airspace management systems. Reduce operating costs while improving safety and efficiency.

Electrified Aircraft Propulsion (EAP)↗
NASA NTRS1985

Fuel containment and damage tolerance in large composite primary aircraft structures. Phase 2: Testing

Technical issues associated with fuel containment and damage tolerance of composite wing structures for transport aircraft were investigated. Material evaluation tests were conducted on two toughened resin composites: Celion/HX1504 and Celion/5245. These consisted of impact, tension, compression, edge delamination, and double cantilever beam tests. Another test series was conducted on graphite/epoxy box beams simulating a wing cover to spar cap joint configuration of a pressurized fuel tank. These tests evaluated the effectiveness of sealing methods with various fastener types and spacings under fatigue loading and with pressurized fuel. Another test series evaluated the ability of the selected coatings, film, and materials to prevent fuel leakage through 32-ply AS4/2220-1 laminates at various impact energy levels. To verify the structural integrity of the technology demonstration article structural details, tests were conducted on blade stiffened panels and sections. Compression tests were performed on undamaged and impacted stiffened AS4/2220-1 panels and smaller element tests to evaluate stiffener pull-off, side load and failsafe properties. Compression tests were also performed on panels subjected to Zone 2 lightning strikes. All of these data were integrated into a demonstration article representing a moderately loaded area of a transport wing. This test combined lightning strike, pressurized fuel, impact, impact repair, fatigue and residual strength.

Sandifer, J. P.↗
NASA NTRS1978

A study on the utilization of advanced composites in commercial aircraft wing structure: Executive summary

The overall wing study objectives are to study and plan the effort by commercial transport aircraft manufacturers to accomplish the transition from current conventional materials and practices to extensive use of advanced composites in wings of aircraft that will enter service in the 1985-1990 time period. Specific wing study objectives are to define the technology and data needed to support an aircraft manufacturer's commitment to utilize composites primary wing structure in future production aircraft and to develop plans for a composite wing technology program which will provide the needed technology and data.

Watts, D. J.↗
NASA NTRS1983

Fuel containment and damage tolerance for large composite primary aircraft structures. Phase 1: Testing

Technical problems associated with fuel containment and damage tolerance of composite material wings for transport aircraft were identified. The major tasks are the following: (1) the preliminary design of damage tolerant wing surface using composite materials; (2) the evaluation of fuel sealing and lightning protection methods for a composite material wing; and (3) an experimental investigation of the damage tolerant characteristics of toughened resin graphite/epoxy materials. The test results, the test techniques, and the test data are presented.

Sandifer, J. P.↗
NASA NTRS1972

Automated synthesis of transonic transports.

The development of a vehicle synthesis program, called TRANSYN, designed to perform automated preliminary design of long-haul transport aircraft is briefly described. The TRANSYN-TST program was used in a study of commercial transonic transports designed for introduction in the early 1980s. The optimum engine cycles of all the study aircraft are within the current state-of-the-art, but fan noise suppression will be required to meet the noise requirements of FAR Part 36. It was found that full use of advanced composite materials in the wing and fuselage structure is neutrally cost effective when compared with aluminum for aircraft designed to cruise in the low transonic regime (Mach 0.90 to 1.0), but that such materials are very cost effective for aircraft designed to cruise in the high transonic regime (Mach 1.0 to 1.15). Finally, increasing speed results in reduced trip times with at most very slight increases in cost in the low transonic regime, but cruise speeds in the high transonic regime result in a significant economic penalty for the conventional configurations considered in this study.

Ardema, M. D.↗
NASA NTRS1991

Status of the FAA flight loads monitoring program

In support of the Federal Aviation Administration Aging Aircraft Research Program, the Agency has established a Flight Loads Data Collection Program for Commercial Aircraft. The objectives of this Program are to: - Review existing data collected by other sources including but not limited to U.S., Foreign, Military, etc. - Collect current operational usage data from both large and small transport aircraft - Develop criteria for future generations of transports. This paper presents the status of the various programs which are completed, underway or planned. The FAA will be collecting, storing, and analyzing the data which characterize typical commercial transport operations. The airframe manufacturers will handle the task of calculating the loads and stresses.

Aging Aircraft↗