Takeoff Obstacle Clearance Procedures: The Feasibility of Extended Second Segment Climb

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Description
To ensure safety is not precluded in the event of an engine failure, the FAA has

established climb gradient minimums enforced through Federal Regulations.

Furthermore, to ensure aircraft do not accidentally impact an obstacle on takeoff due to

insufficient

To ensure safety is not precluded in the event of an engine failure, the FAA has

established climb gradient minimums enforced through Federal Regulations.

Furthermore, to ensure aircraft do not accidentally impact an obstacle on takeoff due to

insufficient climb performance, standard instrument departure procedures have their own

set of climb gradient minimums which are typically more than those set by Federal

Regulation. This inconsistency between climb gradient expectations creates an obstacle

clearance problem: while the aircraft has enough climb gradient in the engine inoperative

condition so that basic flight safety is not precluded, this climb gradient is often not

strong enough to overfly real obstacles; this implies that the pilot must abort the takeoff

flight path and reverse course back to the departure airport to perform an emergency

landing. One solution to this is to reduce the dispatch weight to ensure that the aircraft

retains enough climb performance in the engine inoperative condition, but this comes at

the cost of reduced per-flight profits.

An alternative solution to this problem is the extended second segment (E2S)

climb. Proposed by Bays & Halpin, they found that a C-130H gained additional obstacle

clearance performance through this simple operational change. A thorough investigation

into this technique was performed to see if this technique can be applied to commercial

aviation by using a model A320 and simulating multiple takeoff flight paths in either a

calm or constant wind condition. A comparison of takeoff flight profiles against real

world departure procedures shows that the E2S climb technique offers a clear obstacle

clearance advantage which a scheduled four-segment flight profile cannot provide.
Date Created
2017
Agent

Transonic flow around swept wings: revisiting Von Kármáns similarity rule

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Description
Modern aircraft are expected to fly faster and more efficiently than their predecessors. To improve aerodynamic efficiency, designers must carefully consider and handle shock wave formation. Presently, many designers utilize computationally heavy optimization methods to design wings. While these methods

Modern aircraft are expected to fly faster and more efficiently than their predecessors. To improve aerodynamic efficiency, designers must carefully consider and handle shock wave formation. Presently, many designers utilize computationally heavy optimization methods to design wings. While these methods may work, they do not provide insight. This thesis aims to better understand fundamental methods that govern wing design. In order to further understand the flow in the transonic regime, this work revisits the Transonic Similarity Rule. This rule postulates an equivalent incompressible geometry to any high speed geometry in flight and postulates a “stretching” analogy. This thesis utilizes panel methods and Computational Fluid Dynamics (CFD) to show that the “stretching” analogy is incorrect, but instead the flow is transformed by a nonlinear “scaling” of the flow velocity. This work also presents data to show the discrepancies between many famous authors in deriving the accurate Critical Pressure Coefficient (Cp*) equation for both swept and unswept wing sections. The final work of the thesis aims to identify the correct predictive methods for the Critical Pressure Coefficient.
Date Created
2016
Agent

Comparison of commercial aircraft fuel requirements in regards to FAR, Flight Profile Simulation, and Flight Operational Techniques

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Description
There are significant fuel consumption consequences for non-optimal flight operations. This study is intended to analyze and highlight areas of interest that affect fuel consumption in typical flight operations. By gathering information from actual flight operators (pilots, dispatch, performance engineers,

There are significant fuel consumption consequences for non-optimal flight operations. This study is intended to analyze and highlight areas of interest that affect fuel consumption in typical flight operations. By gathering information from actual flight operators (pilots, dispatch, performance engineers, and air traffic controllers), real performance issues can be addressed and analyzed. A series of interviews were performed with various individuals in the industry and organizations. The wide range of insight directed this study to focus on FAA regulations, airline policy, the ATC system, weather, and flight planning. The goal is to highlight where operational performance differs from design intent in order to better connect optimization with actual flight operations. After further investigation and consensus from the experienced participants, the FAA regulations do not need any serious attention until newer technologies and capabilities are implemented. The ATC system is severely out of date and is one of the largest limiting factors in current flight operations. Although participants are pessimistic about its timely implementation, the FAA's NextGen program for a future National Airspace System should help improve the efficiency of flight operations. This includes situational awareness, weather monitoring, communication, information management, optimized routing, and cleaner flight profiles like Required Navigation Performance (RNP) and Continuous Descent Approach (CDA). Working off the interview results, trade-studies were performed using an in-house flight profile simulation of a Boeing 737-300, integrating NASA legacy codes EDET and NPSS with a custom written mission performance and point-performance "Skymap" calculator. From these trade-studies, it was found that certain flight conditions affect flight operations more than others. With weather, traffic, and unforeseeable risks, flight planning is still limited by its high level of precaution. From this study, it is recommended that air carriers increase focus on defining policies like load scheduling, CG management, reduction in zero fuel weight, inclusion of performance measurement systems, and adapting to the regulations to best optimize the spirit of the requirement.. As well, air carriers should create a larger drive to implement the FAA's NextGen system and move the industry into the future.
Date Created
2014
Agent