Peter Hollingsworth

Application of value-driven design to commercial aeroengine systems

Value-Driven Design provides a framework to enhance the systems engineering processes for the design of large systems. By employing economics in decision making, Value-Driven Design enables rational decision making in terms of the optimum business and technical solution at every level of engineering design. This paper explains the application of ValueDriven Design to the aero-engine system through two case studies, which were conducted through workshops under the Rolls-Royce plc Advanced Cost Modeling Methodologies project. The Surplus Value Theory was utilized to provide a metric that can trade-off component designs with changes in continuous and discrete design variables. Illustrative results are presented to demonstrate how the methodology and modeling approach can be used to evaluate designs and select the value-enhancing solution.

Value-Driven Design

Value-Driven Design is a movement that is using economic theory to transform systems engineering to better utilize optimization so as to improve the design of large systems, particularly in aerospace and defense. This paper describes the ideas and methods that are current in Value-Driven Design.

Investigating the Potential of Using Quota Count as a Design Metric

Quota Count was proposed in the early 1990s as a easily understandable and defensible means of limiting the number of operations of noisier types of aircraft at each of the three London Airports. During its development the Quota Count concept was related to the Sound Exposure Level of a range of aircraft. Since then Quota Count has become one of the de-facto design standards for many larger aircraft. However, there is a lack of rigorous investigation of the applicability of Quota Count as an extensible design metric. This paper provides just such and exploration and determines that Quota Count is a valid metric, extending beyond pure SEL relationships to broader equivalent noise metrics. Additionally, recommendations are made as to how the QC metric can be used in a design decision environment.

An interactive visualization environment for decision making in aircraft engine preliminary design

This paper presents the development of an interactive visualization environment to assist designers and decision makers in selecting a baseline technology level, concept architecture, and parametric design point in aircraft engine prel iminary design. An example study is presented in which the visualization environment is employed to allow a simultaneous comparison of the engine cycle design spaces enabled by each of several sets of technologies applied to a baseline engine design. The environment is generated by first sampling from the design variable ranges compatible with each technology set. This sampling produces a large combinatorial space of discrete engine designs which are then evaluated using surrogate models for engine perfo rmance and economics. The designs produced in this process can be displayed and interactively sorted in the visualization environment to determine the technologies and engine point designs that meet specific performance and economic targets. The primary i nnovative feature of the environment is an interactive scatterplot depicting the characteristics of the engine design space in n dimensions. This scatterplot can be used to display simultaneously both design variables and responses and to filter the discr ete designs to determine regions of the design space that are most promising for further and more detailed exploration. It also serves as a unifying framework for a broader set of techniques suppor ting strategic design decisions .

The development and trial of an unmanned aerial system for the measurement of methane flux from landfill and greenhouse gas emission hotspots

This paper describes the development of a new sampling and measurement method to infer methane flux using proxy measurements of CO2 concentration and wind data recorded by Unmanned Aerial Systems (UAS). The flux method described and trialed here is appropriate to the spatial scale of landfill sites and analogous greenhouse gas emission hotspots, making it an important new method for low-cost and rapid case study quantification of fluxes from currently uncertain (but highly important) greenhouse gas sources. We present a case study using these UAS-based measurements to derive instantaneous methane fluxes from a test landfill site in the north of England using a mass balance model tailored for UAS sampling and co-emitted CO2 concentration as a methane-emission proxy. Methane flux (and flux uncertainty) during two trials on 27 November 2014 and 5 March 2015, were found to be 0.140 kg s-1 (±61% at 1σ), and 0.050 kg s-1 (±54% at 1σ), respectively. Uncertainty contributing to the flux was dominated by ambient variability in the background (inflow) concentration (>40%) and wind speed (>10%); with instrumental error contributing only ∼1-2%. The approach described represents an important advance concerning the challenging problem of greenhouse gas hotspot flux calculation, and offers transferability to a wide range of analogous environments. This new measurement solution could add to a toolkit of approaches to better validate source-specific greenhouse emissions inventories - an important new requirement of the UNFCCC COP21 (Paris) climate change agreement.

An Investigation of Value Modelling for Commercial Aircraft

One of the issues with commercial aircraft design is that most of the methods of developing and propagating requirements allow for nominally satisfying but less than ideal designs to be produced. There is a significant body of work that illustrates the issues that are inherent with the standard requirements flow-down approach. As an attempt to address this, a series of approaches variously named Value-Driven and Value-Centric Design have been proposed. In looking at commercial aircraft and engine design and operations several authors have suggested using a simplified Value model known as Surplus Value. This paper investigates the derivation of and assumptions that are inherent to the standard surplus value formulation. Further, several interesting and potentially useful outcomes of the standard model are investigated including the relationship with discount rate and maximum used programme duration or product life. Lastly, this paper attempts to remove one of the most restrictive assumptions in the basic surplus value formulation. This results in a more general formulation that incorporates basic sales and operating leases plus the ability to provide managed services. The resulting model is more general, but does require more user information to use.

Development of an Airline Revenue Capability Model for Aircraft Design

Typically value based approaches to the design of civil and commercial aircraft, be they net present value, surplus value, or any other utility based approach focus solely on the difference in cost between the alternatives, neglecting changes in revenue which might occur between the two concepts. Alternatively, if they do have a revenue focus, it is based upon simple relationships between payload capacity and revenue, assuming a either a fixed profit margin or fixed yield. This approach works well when comparing two similar or closely related concepts, but falls apart when investigating more radically different systems, e.g. a cruise efficient short take-off and landing concept. By using a value based approach it is relatively simple to structure a decision model to incorporate changing revenue capability. However, the ability to investigate differences in design is very much dependent upon the revenue model and assumptions that are made. If the revenue elasticity is the same for the two concepts then there is no benefit in using a variable revenue approach. However, in the cases where the elasticity is different, the revenue approach offers the potential to more properly investigate some fundamentally different alternative concepts.

A Systems Approach to Investigate the Rigidity of Intermodal Transport Systems

Disturbances within the European transport system have recently generated millions of pounds worth of damages and caused widespread passenger delays. The Eyjafjallajokull volcanic eruption demonstrated how a large scale disturbance within one transport sector can cause a series of knock on effects through other modes of transport, which were illequipped to deal with a significant fluctuation in demand. The cascading effects are a result of the rigid nature of the transport system caused by its complex structure and a lack of suitable preparation. Predicting the behaviour of complex systems is both costly and time consuming due to their data intensive nature. Additionally the transport system is dynamic and it is difficult to perform suitable quantitative analysis. A major challenge is to develop a system that can predict the changes in passenger demand between different modes of transports during a disturbance on one or more of these systems, which will enable the transport industry to implement suitable policies to cope with unexpected demand. This work suggests and analyzes a systems dynamics method incorporating impact analysis techniques which attempts to model and predict the rigid behaviour of an intermodal transport system. The intention of which is to design a predictive tool that can help forecast the direction and magnitude of passenger movement. This paper introduces the concept through the development and initial testing of a simplified dual-mode UK transport model created using system dynamics software. The model is tested with reference to data collected from the recent disturbances and thus suggests its potential predictive uses. As the model is still in the early stages of development further improvements are suggested and the benefits and drawbacks of the approach are discussed. I. Introduction SYSTEM of systems is a complex structure developed from numerous self contained systems, each capable of operating autonomously, that interact with each other through a series of relationships and linkages. These systems are notoriously difficult to analyze due to their emergent and evolutionary behaviour generating complex and often unpredictable interrelationships between each system. As such, systems of systems are often difficult to predict and large levels of uncertainty surround their performance characteristics 1 . Complex systems are found through many disciplines, developing from industry 2 into diverse fields such as biology 3 and climatology 4 . Consequentially, a number of negative traits associated with the behaviour can be seen within complex systems. Rigidity within the transport system arises due to the nature of the complex interrelationships between different transport modes. Due to the reliance of each transport mode on another, a large disturbance can cause widespread closures and delays, with large costs associated with system recovery. As each system was designed separately the interrelationships have developed over time meaning they tend to be dynamic, hence fluctuations in the relationships can depend on a number of factors largely based around human behaviour and trends. The complex behaviour of

The Philosophy of Design Education at the University of Manchester

The University of Manchester was created in 2004 through the merger of the Victoria University of Manchester (VUM) and the University of Manchester Institute of Science & Technology (UMIST). Both of the constituent universities had an undergraduate aerospace engineering program. The combination of the two undergraduate programs along with the development and initiation of a post-graduate Master of Science program required a reassessment of the design units at the university. As such the current aerospace engineering curriculum has evolved and is continuing to evolve from those of it predecessors and the development and inclusion of new course material. This evolution has included a restructuring of unit contents, an increased focus on defending design decisions and the breadth of the systems design process. The changes to date have focused on the 3rd and 4th years of the BEng and MEng programs respectively and the inclusion of MSc students. Future work will incorporate changes to the 1st and 2nd years along with further changes to the existing units.

Development of a Surplus Value Parameter for use in Initial Aircraft Conceptual Design

Simple constraints analysis, as taught to most aerospace engineering students gives little guidance as to exactly which design point should be selected. There is a recent body of work that attempts to solve this for initial designs, without having to fully size the new aircraft concept. The best of these focuses on maximizing a ?Range Parameter? which leads to minimizing gross weight for transport aircraft. However, this is not guaranteed to maximize the value of the new design. This paper presents a corresponding surplus value parameter which is designed to provide just that capability. Furthermore, it shows that in at least some cases the resulting optimum design point will shift from that suggested by the range parameter