Engineering topics

Johnson, Jesse

Publications and source records attributed to Johnson, Jesse.

9 records

NASA NTRS2013

Insights into Spatial Sensitivities of Ice Mass Response to Environmental Change from the SeaRISE Ice Sheet Modeling Project I: Antarctica

Atmospheric, oceanic, and subglacial forcing scenarios from the Sea-level Response to Ice Sheet Evolution (SeaRISE) project are applied to six three-dimensional thermomechanical ice-sheet models to assess Antarctic ice sheet sensitivity over a 500 year timescale and to inform future modeling and field studies. Results indicate (i) growth with warming, except within low-latitude basins (where inland thickening is outpaced by marginal thinning); (ii) mass loss with enhanced sliding (with basins dominated by high driving stresses affected more than basins with low-surface-slope streaming ice); and (iii) mass loss with enhanced ice shelf melting (with changes in West Antarctica dominating the signal due to its marine setting and extensive ice shelves; cf. minimal impact in the Terre Adelie, George V, Oates, and Victoria Land region of East Antarctica). Ice loss due to dynamic changes associated with enhanced sliding and/or sub-shelf melting exceeds the gain due to increased precipitation. Furthermore, differences in results between and within basins as well as the controlling impact of sub-shelf melting on ice dynamics highlight the need for improved understanding of basal conditions, grounding-zone processes, ocean-ice interactions, and the numerical representation of all three.

SeaRISE↗

NASA NTRS2001

Evaluation of the National Throughput Benefits of the Civil Tilt Rotor

The air transportation system is a key part of the U.S. and global economic infrastructure. In recent years, this system, by any measure of usage - operations, enplanements, or revenue passenger miles (RPMs) - has grown rapidly. The rapid growth in demand has not been matched; however, by commensurate increases in the ability of airports and the airspace system to handle the additional traffic. As a result, the air transportation system is approaching capacity and airlines will face excessive delays or significant constraints on service unless capacity is expanded. To expand capacity, the air traffic management system must be improved. To improve the air traffic management system, the National Aeronautics and Space Administration (NASA) Aerospace Technology Enterprise developed the strategic goal of tripling air traffic throughput over the next 10 years, in all weather conditions, while at least maintaining current safety standards. As the first step in meeting that goal, the NASA Intercenter Systems Analysis Team (ISAT) is evaluating the contribution of existing programs to meet that goal. A major part of the study is an examination of the ability of the National Airspace System (NAS) to meet the predicted growth in travel demand and the potential benefits of technology infusion to expand NAS capacity. We previously analyzed the effects of the addition of two technology elements - Terminal Area Productivity (TAP) and Advanced Air Transportation Technologies (AATT). The next program we must analyze is not specific to airspace or aircraft technology. The program incorporates a fundamentally different vehicle to improve throughput: the civil tilt rotor (CTR). The CTR has the unique operating characteristic of being able to take off and land like a rotorcraft (vertical take off and landing, or VTOL, capability) but cruises like a traditional fixed-wing aircraft. The CTR also can operate in a short take off and landing (STOL) mode; generally, with a greater payload capacity (i.e., more passengers) than when operating in the VTOL mode. CTR could expand access to major airports without interfering with fixed-wing aircraft operating on congested runways and it could add service to new markets without the infrastructure support needed for fixed-wing aircraft. During FY 1999, we preliminarily assessed the feasibility of operating CTRs at two major U.S. airports as part of the annual review of NASA aerospace goals by the ISAT. This current study expands the analysis and concepts of that study to the complete NAS to quantify the national throughput effects of the CTR.

Johnson, Jesse↗

NASA NTRS2001

A Small Aircraft Transportation System (SATS) Demand Model

The Small Aircraft Transportation System (SATS) demand modeling is a tool that will be useful for decision-makers to analyze SATS demands in both airport and airspace. We constructed a series of models following the general top-down, modular principles in systems engineering. There are three principal models, SATS Airport Demand Model (SATS-ADM), SATS Flight Demand Model (SATS-FDM), and LMINET-SATS. SATS-ADM models SATS operations, by aircraft type, from the forecasts in fleet, configuration and performance, utilization, and traffic mixture. Given the SATS airport operations such as the ones generated by SATS-ADM, SATS-FDM constructs the SATS origin and destination (O&D) traffic flow based on the solution of the gravity model, from which it then generates SATS flights using the Monte Carlo simulation based on the departure time-of-day profile. LMINET-SATS, an extension of LMINET, models SATS demands at airspace and airport by all aircraft operations in US The models use parameters to provide the user with flexibility and ease of use to generate SATS demand for different scenarios. Several case studies are included to illustrate the use of the models, which are useful to identify the need for a new air traffic management system to cope with SATS.

Long, Dou↗

NASA NTRS2001

Civil Tiltrotor Feasibility Study for the New York and Washington Terminal Areas

NASA tasked LMI to assess the potential contributions of a yet-undeveloped Civil Tiltrotor aircraft (CTR) in improving capacity in the National Airspace System in all weather conditions. The CTRs studied have assumed operating parameters beyond current CTR capabilities. LMI analyzed CTRs three ways: in fast-time terminal area modeling simulations of New York and Washington to determine delay and throughput impacts; in the Integrated Noise Model, to determine local environmental impact; and with an economic model, to determine the price viability of a CTR. The fast-time models encompassed a 250 nmi range and included traffic interactions from local airports. Both the fast-time simulation and the noise model assessed impacts from traffic levels projected for 1999, 2007, and 2017. Results: CTRs can reduce terminal area delays due to concrete congestion in all time frames. The maximum effect, the ratio of CTRs to jets and turboprop aircraft at a subject airport should be optimized. The economic model considered US traffic only and forecasted CTR sales beginning in 2010.

Stouffer, Virginia↗

NASA NTRS2001

Development Cycle Time Simulation for Civil Aircraft

Cycle Time Reduction (CTR) will be one of the major factors affecting the future of the civil aerospace industry. This focus is the end reflection of the level of competition in the commercial large carrier aircraft industry. Aircraft manufacturer must minimize costs and pass a portion of those savings onto buyers. CTR is one strategy used to move the manufacturing firm down the cost curve. The current NASA Airframe Development Cycle Time Reduction Goal is 50% by year 2022. This goal is not achievable based on the program analysis done by the LMI/GRA team. This may mean that the current roster of NASA CTR programs needs to be reexamined or that the program technology progress factors, as determined by the NASA experts, were understated. Programs that duplicate the reductions of others should be replaced with non-duplicative programs. In addition, new programs targeting a specific part of the cycle can be developed.

Spitz, William↗

NASA NTRS1999

Aviation System Analysis Capability Air Carrier Investment Model-Cargo

The purpose of the Aviation System Analysis Capability (ASAC) Air Cargo Investment Model-Cargo (ACIMC), is to examine the economic effects of technology investment on the air cargo market, particularly the market for new cargo aircraft. To do so, we have built an econometrically based model designed to operate like the ACIM. Two main drivers account for virtually all of the demand: the growth rate of the Gross Domestic Product (GDP) and changes in the fare yield (which is a proxy of the price charged or fare). These differences arise from a combination of the nature of air cargo demand and the peculiarities of the air cargo market. The net effect of these two factors are that sales of new cargo aircraft are much less sensitive to either increases in GDP or changes in the costs of labor, capital, fuel, materials, and energy associated with the production of new cargo aircraft than the sales of new passenger aircraft. This in conjunction with the relatively small size of the cargo aircraft market means technology improvements to the cargo aircraft will do relatively very little to spur increased sales of new cargo aircraft.

Johnson, Jesse↗

NASA NTRS1999

Modeling Air Traffic Management Technologies with a Queuing Network Model of the National Airspace System

This report describes an integrated model of air traffic management (ATM) tools under development in two National Aeronautics and Space Administration (NASA) programs -Terminal Area Productivity (TAP) and Advanced Air Transport Technologies (AATT). The model is made by adjusting parameters of LMINET, a queuing network model of the National Airspace System (NAS), which the Logistics Management Institute (LMI) developed for NASA. Operating LMINET with models of various combinations of TAP and AATT will give quantitative information about the effects of the tools on operations of the NAS. The costs of delays under different scenarios are calculated. An extension of Air Carrier Investment Model (ACIM) under ASAC developed by the Institute for NASA maps the technologies' impacts on NASA operations into cross-comparable benefits estimates for technologies and sets of technologies.

Long, Dou↗

NASA NTRS1999

A Method for Forecasting the Commercial Air Traffic Schedule in the Future

This report presents an integrated set of models that forecasts air carriers' future operations when delays due to limited terminal-area capacity are considered. This report models the industry as a whole, avoiding unnecessary details of competition among the carriers. To develop the schedule outputs, we first present a model to forecast the unconstrained flight schedules in the future, based on the assumption of rational behavior of the carriers. Then we develop a method to modify the unconstrained schedules, accounting for effects of congestion due to limited NAS capacities. Our underlying assumption is that carriers will modify their operations to keep mean delays within certain limits. We estimate values for those limits from changes in planned block times reflected in the OAG. Our method for modifying schedules takes many means of reducing the delays into considerations, albeit some of them indirectly. The direct actions include depeaking, operating in off-hours, and reducing hub airports'operations. Indirect actions include using secondary airports, using larger aircraft, and selecting new hub airports, which, we assume, have already been modeled in the FAA's TAF. Users of our suite of models can substitute an alternative forecast for the TAF.

Long, Dou↗

NASA NTRS1998

A Method for Making Cross-Comparable Estimates of the Benefits of Decision Support Technologies for Air Traffic Management

We present a general method for making cross comparable estimates of the benefits of NASA-developed decision support technologies for air traffic management, and we apply a specific implementation of the method to estimate benefits of three decision support tools (DSTs) under development in NASA's advanced Air Transportation Technologies Program: Active Final Approach Spacing Tool (A-FAST), Expedite Departure Path (EDP), and Conflict Probe and Trial Planning Tool (CPTP). The report also reviews data about the present operation of the national airspace system (NAS) to identify opportunities for DST's to reduce delays and inefficiencies.

Lee, David↗