Approaches to Representing Aircraft Fuel Efficiency Performance for the Purpose of a Commercial Aircraft Certification Standard

Increasing concern over the potential harmful effects of green house gas emissions from various sources has motivated the consideration of an aircraft certification standard as one way to reduce aircraft CO2 emissions and mitigate aviation impacts on the climate. In order to develop a commercial aircraft certification standard, a fuel efficiency performance metric and the condition at which it is evaluated must be determined. The fuel efficiency metric form of interest to this research is fuel/range, where fuel and range can either be evaluated over the course of a reference mission or at a single, instantaneous point. A mission-­‐based metric encompasses all phases of flight and is robust to changes in technology; however, definition of the reference mission requires many assumptions and is cumbersome for both manufacturers and regulators. An instantaneous metric based on fundamental aircraft parameters measures the fuel efficiency performance of the aircraft at a single point, greatly reducing the complexity of the standard and certification process; however, a single point might not be robust to future changes in aircraft technology. In this thesis, typical aircraft operations are assessed in order to develop evaluation assumptions for a mission-­‐based metric, Block Fuel divided by Range (BF/R), and an instantaneous metric, incremental fuel burn per incremental distance (inverse Specific Air Range (1/SAR)). Operating patterns and fuel burn maps are used to demonstrate the importance of mission range on fleet fuel burn, and thus the importance of a properly defined range evaluation condition for BF/R. An evaluation condition of 40% of the range at Maximum Structural Payload (MSP) limited by Maximum Takeoff Weight (MTOW) is determined to be representative for the mission-­‐based metric. A potential evaluation condition for 1/SAR is determined to be optimal speed and altitude for a representative mid-­‐cruise weight defined by half of the difference between MTOW and Maximum Zero Fuel Weight (MZFW). To demonstrate suitability as a potential surrogate for BF/R, correlation of 1/SAR with BF/R is shown for the current fleet, and a case study of potential future aircraft technologies is presented to show the correlation of improvements in the 1/SAR metric with improvements in BF/R.Thanks to my sponsors at the FAA and EPA

Transitioning The U.S. Air Transportation System To Higher Fuel Costs

The air transportation system enables economic growth and provides significant social benefits. Future increases and volatility in oil prices, as well as climate change policies, are likely to increase the effective cost of fuel. We investigate the expected impacts of higher fuel costs on the U.S. domestic air transportation system and discuss policy options to reduce negative economic and social effects. The 2004-08 fuel price surge is used as a historical case study. A stochastic simulation model is developed using price elasticity of demand assumptions and flight leg fuel burn estimates to understand the impacts of higher fuel costs. It was found that a 50% increase in fuel prices is expected to result in a 12% reduction in ASMs if all cost increases pass through to passengers. System revenues are expected to decrease marginally for fuel price increases up to 50%, but higher increases may result in significant revenue reductions. Small airports are expected to experience relatively larger decreases and greater volatility in traffic. Older aircraft, flying sectors significantly below their optimal fuel efficiency range, are expected to experience the greatest reductions in capacity. An airline case study demonstrates that a regional carrier may be less sensitive to increased fuel prices than other business models. Policy options to maintain small community access, to manage airport traffic volatility, and to improve fleet fuel efficiency are discussed. To transition the U.S. air transportation system to higher fuel costs, stakeholder action will be required.MIT Partnership for AiR Transportation Noise & Emissions Reduction (PARTNER) provided access to the Piano-X aircraft performance database. The Transportation Research Board’s (TRB) Airport Cooperative Research Program (ACRP) supported this work through the Graduate Research Award Program on Public-Sector Aviation Issues

Inline Electrical Connector Mate/Demate Pliers

Military and aerospace industries use Mil-Spec type electrical connections on bulkhead panels that require inline access for mate and demate operations. These connectors are usually in tight proximity to other connectors, or recessed within panels. The pliers described here have been designed to work in such tight spaces, and consist of a mirrored set of parallel handles, two cross links, two return springs, and replaceable polyurethane-coated end effectors. The polyurethane eliminates metal-to-metal contact and provides a high-friction surface between the jaw and the connector. Operationally, the user would slide the pliers over the connector shell until the molded polyurethane lip makes contact with the connector shell edge. Then, by squeezing the handles, the end effector jaws grip the connector shell, allowing the connector to be easily disconnected by rotating the pliers. Mating the connector occurs by reversing the prescribed procedure, except the connector shell is placed into the jaws by hand. The molded lip within the jaw allows the user to apply additional force for difficult-to-mate connectors. Handle design has been carefully examined to maximize comfort, limit weight, incorporate tether locations, and improve ergonomics. They have been designed with an off-axis offset for wiring harness clearance, while placing the connector axis of rotation close to the user s axis of wrist rotation. This was done to eliminate fatigue during multiple connector panel servicing. To limit handle opening width, with user ergonomics in mind, the pliers were designed using a parallel jaw mechanism. A cross-link mechanism was used to complete this task, while ensuring smooth operation

Approaches to representing aircraft performance for the purpose of a CO₂ certification standard

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 79-80).Increasing concern over the potential harmful effects of green house gas emissions from various sources has motivated the consideration of an aircraft certification standard as one way to reduce aircraft C02 emissions and mitigate aviation impacts on the climate. In order to develop a commercial aircraft certification standard, a fuel efficiency performance metric and the condition at which it is evaluated must be determined. The fuel efficiency metric form of interest to this research is fuel/range, where fuel and range can either be evaluated over the course of a reference mission or at a single, instantaneous point. A mission-based metric encompasses all phases of flight and is robust to changes in technology; however, definition of the reference mission requires many assumptions and is cumbersome for both manufacturers and regulators. An instantaneous metric based on fundamental aircraft parameters measures the fuel efficiency performance of the aircraft at a single point, greatly reducing the complexity of the standard and certification process; however, a single point might not be robust to future changes in aircraft technology. In this thesis, typical aircraft operations are assessed in order to develop evaluation assumptions for a mission-based metric, Block Fuel divided by Range (BF/R), and an instantaneous metric, incremental fuel burn per incremental distance (inverse Specific Air Range (1/SAR)). Operating patterns and fuel burn maps are used to demonstrate the importance of mission range on fleet fuel burn, and thus the importance of a properly defined range evaluation condition for BF/R. An evaluation condition of 40% of the range at Maximum Structural Payload (MSP) limited by Maximum Takeoff Weight (MTOW) is determined to be representative for the mission-based metric. A potential evaluation condition for 1/SAR is determined to be optimal speed and altitude for a representative mid-cruise weight defined by half of the difference between MTOW and Maximum Zero Fuel Weight (MZFW). To demonstrate suitability as a potential surrogate for BF/R, correlation of 1/SAR with BF/R is shown for the current fleet, and a case study of potential future aircraft technologies is presented to show the correlation of improvements in the 1/SAR metric with improvements in BF/R.by Brian M. Yutko.S.M

The impact of aircraft design reference mission on fuel efficiency in the air transportation system

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, February 2014.Cataloged from PDF version of thesis. "October 2013."Includes bibliographical references (pages 153-157).Existing commercial aircraft are designed for high mission flexibility, which results in decreased fuel efficiency throughout the operational life of an aircraft. The objective of this research is to quantify the impact of this practice and other non-optimal emergent behaviors of the current global air transportation system. The analysis focuses on improvements that can be made using existing technology. Previous attempts at performing this type of analysis, especially the joint optimization of aircraft design and operations, have been hindered by problem complexity and computational time. In order to overcome these issues and perform the analysis on a global scale, a machine-learning algorithm is used to create a computationally efficient artificial neural network relating aircraft design and off-design mission performance to operational fuel burn and flight time. The data used to train the aircraft performance neural network is generated from an extensive sample of new vehicles optimized for minimum fuel burn on an extremely broad combination of Design Reference Missions (design-payload, -range, and cruise Mach). The resulting comprehensive model of aircraft performance is capable of solving large-scale air transportation network optimization problems. A set of scenarios is analyzed to both establish the limits of the major contributors to system fuel consumption and determine potential realistic benefits from introducing new aircraft with varying design reference missions. Results indicate that approximately 33% of current system fuel consumption is due to the slow retirement and replacement of aircraft in the operational fleet. Additionally, a significant pool of potential fuel burn savings can be realized by designing aircraft closer to their intended operating regime. Multiple large-scale optimization scenarios are presented, including the optimal choice of new aircraft designs for fixed cruise Mach numbers and the globally optimum aircraft choices given any cruise Mach. It is found that reducing design cruise speed can yield system fuel benefits on the order of 7%. Fuel stops are shown as a potentially promising method to operate long-haul missions closer to the maximum fuel efficiency range of an aircraft, and also as a way to mitigate the impact of designing high-efficiency, short-range aircraft that can no longer fly long haul missions directly.by Brian Yutko.Ph. D

An Investigation of the Potential Implications of a CO2 Emission Metric on Future Aircraft Designs

07-CNE-GIT-001 (Amendment No. 015)09-C-NEGIT-001 (Amendment No. 003)DTFAWA-05-D-00012 (Task Order No. 0007)This work was funded by the FAA under Partnership for AiR Transportation Noise and Emissions Reduction, PARTNER: a FAA/NASA/Transport Canada sponsored Center of Excellence, under Award Nos.: 07-CNE-GIT-001 (Amendment No. 015), 09-C-NEGIT-001 (Amendment No. 003), and DTFAWA-05-D-00012 (Task Order No. 0007). Citation: Nam T., Kirby M., Burdette G., Lim D., Isley S., Bonnefoy P., Hansman R. J., Hileman J., Waitz I., Yutko B., \u201cAn Investigation of the Potential Implications of a CO2 Emission Metric on Future Aircraft Designs,\u201d International Council of the Aeronautical Sciences (ICAS), Nice, France, Sept. 2010.Shifts in vehicle design trends due to aviation CO2 emission metrics are explored. The combined effects of traditional performance and stringent environmental constraints on several vehicle design spaces are observed, in the presence of future technologies. Potential design implications and unintended consequences of candidate metrics are identified