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At least 145 records · Page 8

Development of 2 underseat energy absorbers for application to crashworthy passenger seats for general aviation aircraft

This report presents the methodology and results of a program conducted to develop two underseat energy absorber (E/A) concepts for application to nonadjustable crashworthy passenger seats for general aviation aircraft. One concept utilizes an inflated air bag, and the other, a convoluted sheet metal bellows. Prototypes of both were designed, built, and tested. Both concepts demonstrated the necessary features of an energy absorber (load-limiter); however, the air bag concept is particularly encouraging because of its light weight. Several seat frame concepts also were investigated as a means of resisting longitudinal and lateral loads and of guiding the primary vertical stroke of the underseat energy absorber. Further development of a seat system design using the underseat energy absorbers is recommended because they provide greatly enhanced crash survivability as compared with existing general aviation aircraft seats.

Warrick, J. C.↗

Combined effect of noise and vibration on passenger acceptance

An extensive research program conducted at NASA Langley Research Center to develop a comprehensive model of passenger comfort response to combined noise and vibration environments has been completed. This model was developed for use in the prediction and/or assessment of vehicle ride quality and as a ride quality design tool. The model has the unique capability to transform individual elements of vehicle interior noise and vibration into subjective units and combining the subjective units to produce a total subjective discomfort index as well as the other useful subjective indices. This paper summarizes the basic approach used in the development of the NASA ride comfort model, presents some of the more fundamental results obtained, describes several application of the model to operational vehicles, and discusses a portable, self-contained ride quality meter system that is a direct hardware/software implementation of the NASA comfort algorithm.

Leatherwood, J. D.↗

Evaluation of half wave induction motor drive for use in passenger vehicles

Research performed at the University of Missouri-Columbia to devise and design a lower cost inverter induction motor drive for electrical propulsion of passenger vehicles is described. A two phase inverter motor system is recommended. The new design is predicted to provide comparable vehicle performance, improved reliability and a cost advantage for a high production vehicle, decreased total rating of the power semiconductor switches, and a somewhat simpler control hardware compared to the conventional three phase bridge inverter motor drive system. The major disadvantages of the two phase inverter motor drive are that it is larger and more expensive than a three phase machine, the design of snubbers for the power leakage inductances produce higher transient voltages, and the torque pulsations are relatively large because of the necessity to limit the inverter switching frequency to achieve high efficiency.

Hoft, R. G.↗

Design, development and trials of an airline passenger telephone system

The design, development and trials of a satellite telephone system for airline passengers is described. The requirements for ground and space infrastructure are discussed and the aeronautical system is described. Design criteria for the antennas and avionic boxes are given and system operation and technical flight trial requirements are discussed, together with test methodology and development towards fully commercial trials. Finally, an indication of development requirements to achieve the desired aims of airline users is given.

Schoenenberger, Jim↗

Civil tiltrotor missions and applications. Phase 2: The commercial passenger market

The commercial passenger market for the civil tiltrotor was examined in phase 2. A market responsive commercial tiltrotor was found to be technically feasible, and a significant worldwide market potential was found to exist for such an aircraft, especially for relieving congestion in urban area-to-urban area service and for providing cost effective hub airport feeder service. Potential technical obstacles of community noise, vertiport area navigation, surveillance, and control, and the pilot/aircraft interface were determined to be surmountable. Nontechnical obstacles relating to national commitment and leadership and development of ground and air infrastructure were determined to be more difficult to resolve; an innovative public/private partnership is suggested to allow coordinated development of an initial commercial tiltrotor network to relieve congestion in the crowded US Northeast corridor by the year 2000.

Thompson, P.↗

Research needs for a commercial passenger tiltrotor

The National Aeronautics and Space Administration (NASA) recently completed a series of contracts and studies that examined the technology needs for a tiltrotor aircraft in commercial service as well as military missions. The commercial needs arise out of market-driven requirements that include vertiport location and design, passenger comfort levels and competitive costs. The military needs are derived from time-sensitive missions and combat effectiveness. In response to these results, NASA has decided to address the commercial needs first, recognizing that there will be eventual payoff to military missions as well. Research goals were explored in acoustics, flight dynamics, human factors and displays, dynamics and loads, propulsion, safety, and configuration design. The paper describes the development of these goals from the market requirements and the implications for possible research activities. The aircraft issues that were addressed include number of blades, advanced blade planforms, steep approach requirements and pilot-cockpit interface for civil operations.

Unger, George↗

Graphical and Statistical Analysis of Airplane Passenger Cabin RF Coupling Paths to Avionics

Portable wireless technology provides many benefits to modern day travelers. Over the years however, numerous reports have cited portable electronic devices (PEDs) as a possible cause of electromagnetic interference (EMI) to aircraft navigation and communication radio systems. PEDs may act as transmitters, both intentional and unintentional, and their signals may be detected by the various radio receiver antennas installed on the aircraft. Measurement of the radiated field coupling between passenger cabin locations and aircraft communication and navigation receivers, via their antennas is defined herein as interference path loss (IPL). IPL data is required for assessing the threat of PEDs to aircraft radios, and is very dependent upon airplane size, the interfering transmitter position within the airplane, and the location of the particular antenna for the aircraft system of concern. NASA Langley Research Center, Eagles Wings Inc., and United Airlines personnel performed extensive IPL measurements on several Boeing 737 airplanes.

Jafri, Madiha↗

RF Coupling into the Fuel Tank of a Large Transport Aircraft from Intentionally Transmitting Peds in the Passenger Cabin

An investigation was performed to study the potential for radio frequency (RF) power radiated from Portable Electronic Devices (PEDs) to create an arcing/sparking event within the fuel tank of a large transport aircraft. This paper describes the experimental methods used for measuring RF coupling to the fuel tank and Fuel Quantity Indication System (FQIS) wiring from PED sources located in the passenger cabin. To allow comparison of voltage/current data obtained in a laboratory chamber FQIS installation to an actual aircraft FQIS installation, aircraft fuel tank RF reverberation characteristics were also measured. Results from the measurements, along with a survey of threats from typical intentional transmitting PEDs are presented. The resulting worst-case power coupled onto fuel tank FQIS wiring is derived. The same approach can be applied to measure RF coupling into various other aircraft systems.

Nguyen, Truong X.↗

Preliminary Sizing of 120-Passenger Advanced Civil Rotorcraft Concepts

The results of a preliminary sizing study of advanced civil rotorcraft concepts that are capable of carrying 120 passengers over a range of 1,200 nautical miles are presented. The cruise altitude of these rotorcraft is 30,000 ft and the cruise velocity is 350 knots. The mission requires a hover capability, creating a runway independent solution, which might aid in reducing strain on the existing airport infrastructure. Concepts studied are a tiltrotor, a tandem rotor compound, and an advancing blade concept. The first objective of the study is to determine the relative merits of these designs in terms of mission gross weight, engine size, fuel weight, aircraft purchase price, and direct operating cost. The second objective is to identify the enabling technology for these advanced heavy lift civil rotorcraft.

vanAken, Johannes M.↗

Wing Configuration Impact on Design Optimums for a Subsonic Passenger Transport

This study sought to compare four aircraft wing configurations at a conceptual level using a multi-disciplinary optimization (MDO) process. The MDO framework used was created by Georgia Institute of Technology and Virginia Polytechnic Institute and State University. They created a multi-disciplinary design and optimization environment that could capture the unique features of the truss-braced wing (TBW) configuration. The four wing configurations selected for the study were a low wing cantilever installation, a high wing cantilever, a strut-braced wing, and a single jury TBW. The mission that was used for this study was a 160 passenger transport aircraft with a design range of 2,875 nautical miles at the design payload, flown at a cruise Mach number of 0.78. This paper includes discussion and optimization results for multiple design objectives. Five design objectives were chosen to illustrate the impact of selected objective on the optimization result: minimum takeoff gross weight (TOGW), minimum operating empty weight, minimum block fuel weight, maximum start of cruise lift-to-drag ratio, and minimum start of cruise drag coefficient. The results show that the design objective selected will impact the characteristics of the optimized aircraft. Although minimum life cycle cost was not one of the objectives, TOGW is often used as a proxy for life cycle cost. The low wing cantilever had the lowest TOGW followed by the strut-braced wing.

Wells, Douglas P.↗

Exploring Concepts of Operations for On-Demand Passenger Air Transportation

In recent years, a surge of interest in "flying cars" for city commutes has led to rapid development of new technologies to help make them and similar on-demand mobility platforms a reality. To this end, this paper provides analyses of the stakeholders involved, their proposed operational concepts, and the hazards and regulations that must be addressed. Three system architectures emerged from the analyses, ranging from conventional air taxi to revolutionary fully autonomous aircraft operations, each with vehicle safety functions allocated differently between humans and machines. Advancements for enabling technologies such as distributed electric propulsion and artificial intelligence have had major investments and initial experimental success, but may be some years away from being deployed for on-demand passenger air transportation at scale.

Nneji, Victoria Chibuogu↗

Urban Air Mobility Operational Concept (OpsCon) Passenger-Carrying Operations

Urban Air Mobility (UAM) is the name chosen for the concept of using the airspace over urban areas to satisfy the public imperative for fast and efficient transportation within growing metropolitan areas. This Operational Concept (OpsCon) describes a community vision of the projected evolution of urban air service with vehicles capable of carrying one or more passengers.

Urban Air Mobility (UAM)↗

Multidisciplinary Systems Analysis of a Six Passenger Quadrotor Urban Air Mobility Vehicle Powertrain

There is a high degree of research interest in the design space for electric vertical takeoff and landing (eVTOL) vehicles, because these vehicles are seen as key enablers for urban air mobility (UAM). This work further explores the eVTOL design space, by presenting analysis of a six-passenger eVTOL quadrotor powertrain, with integrated power, propulsion, and thermal management systems modeled using the Numerical Propulsion System Simulation (NPSS) and the NPSS Power System Library. Four architectures are modeled at the same design point and compared over a design mission. Results from an architecture comparison study show that a hybrid architecture performs best in terms of cruise range, however, the hybrid needs batteries with high specific energy and specific power in order to obtain a benefit vs turboelectric architectures. Sensitivity studies are conducted to show correlations between component parameters and system metrics. This data provides useful indicators for further technological improvement. Lastly, an initial TMS model is presented, and sensitivity studies on TMS design parameters are presented as well, to show high level TMS design trends.

electrified propulsion↗

Multidisciplinary Systems Analysis of a Six Passenger Quadrotor Urban Air Mobility Vehicle Powertrain

There is a high degree of research interest in the design space for electric vertical takeoff and landing (eVTOL) vehicles, because these vehicles are seen as key enablers for urban air mobility (UAM). This work further explores the eVTOL design space, by presenting analysis of a six-passenger eVTOL quadrotor powertrain, with integrated power, propulsion, and thermal management systems modeled using the Numerical Propulsion System Simulation (NPSS) and the NPSS Power System Library. Four architectures are modeled at the same design point and compared over a design mission. Results from an architecture comparison study show that a hybrid architecture performs best in terms of cruise range, however, the hybrid needs batteries with high specific energy and specific power in order to obtain a benefit vs turboelectric architectures. Sensitivity studies are conducted to show correlations between component parameters and system metrics. This data provides useful indicators for further technological improvement. Lastly, an initial TMS model is presented, and sensitivity studies on TMS design parameters are presented as well, to show high level TMS design trends.

evtol↗

An Initial Concept for Intermediate-State, Passenger-Carrying Urban Air Mobility Operations

This paper describes a general “vision” concept of operations (ConOps) for intermediate state, passenger-carrying urban air mobility (UAM) missions that has been developed jointly by NASA and Deloitte with input from stakeholders in the UAM ecosystem. This vision ConOps provides a broad overview of some of the high-level requirements for realizing the simultaneous operation of hundreds of aircraft over a single metropolitan area in a wide range of weather conditions as conceptualized by many visionaries at the time of its publication. The concepts contained in this vision ConOps are intended to provide a starting point for further discussions and investigations into how UAM operations can be best enabled. Consequently, we also describe some of the areas where additional research is required before a detailed baseline ConOps can be finalized.

urban air mobility↗

High-Fidelity Analysis of Six-Passenger Quadrotor Air Taxi Concept

A code-to-code comparison has been performed for high-fidelity simulations ofNASA’s six-passenger quadrotor air taxi con- cept vehicle. Themultidisciplinary simulations combine comprehensive rotorcraft dynamics with high-fidelity fluid dynamics obtained from an unsteady Navier-Stokes computational fluid dynamics code. The results are then compared with those in the literature. A quantitative comparison of converged trim angles has been performed and normal force, chord force, and pitching-moment coefficients arepresented for qualitativecomparison.

eVTOL↗

Electrical Energy Storage Design Space Exploration for a Hybrid-Electric Six Passenger Quadrotor

Hybrid-electric architectures are a promising means to achieve clean and efficient aircraft propulsion needed for small, short-range electric vertical takeoff and landing (eVTOL) class vehicles. This paper explores the design space for a six-passenger quadrotor hybrid-electric propulsion system and shows that hybrid architectures that are more efficient than engine-only architectures can be built with near-term battery technology (~150 Wh/kg at the pack level). Data obtained shows that hybrid-electric propulsion systems can achieve 28 percent block fuel reduction and 27 percent total energy cost savings over a 120 nautical mile (nmi) mission compared to conventional turboshaft architectures. This work suggests that hybrids are likely the most efficient architectures that can be produced in the near term for this class of vehicle and motivates further development in this area.

Hybrid-electric↗