©2011 Rolls-Royce plc The information in this document is the property of Rolls-Royce plc and may not be copied or communicated to a third party, or used for any purpose other than that for which it is supplied without the express written consent of Rolls-Royce plc. This information is given in good faith based upon the latest information available to Rolls-Royce plc, no warranty or representation is given concerning such information, which must not be taken as establishing any contractual or other commitment binding upon Rolls-Royce plc or any of its subsidiary or associated companies. How Big is Yours? The use of Comparator tools in Estimation Andy Nolan BSc Hons, CEng, FBCS, CITP Chief of Software improvement – The Software Centre of Excellence Satpaul Sall BSc Hons Software Technologist – The Software Centre of Excellence Andy Nolan BSc Hons, CEng, FBCS, CITP Chief of Software improvement – The Software Centre of Excellence Satpaul Sall BSc Hons Software Technologist – The Software Centre of Excellence

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3 A Brief History of Engine Controls The Control Systems department is responsible for the Engine Electronic Controllers (EECs) for a range of small and large gas turbine engines for the aerospace industry. The software is developed to DO- 178B Level-A standards The company has been developing high integrity software for over 20 years and has extensive data on its processes and productivity. We have the largest order book in history, new engine development places greater demand on the software team (shorter time scales and lower costs)

Rolls-Royce data 4 COCOMO A unifying language Software Supplier COCOMO Challenging our supplier costs. Hardware COCOMO Hardware Supplier COCOMO Using many SW factors to estimate hardware engineering CO-Imp-MO Improvement COCOMO Using COCOMO to identify & validate improvements CO-RISK-MO Risk Management Using the model to identify and quantify risk CO-Bus-MO Enterprise business performance Benchmarking the business Estimation & eliciting key assumptions & negotiation

©2011 Rolls-Royce plc The information in this document is the property of Rolls-Royce plc and may not be copied or communicated to a third party, or used for any purpose other than that for which it is supplied without the express written consent of Rolls-Royce plc. This information is given in good faith based upon the latest information available to Rolls-Royce plc, no warranty or representation is given concerning such information, which must not be taken as establishing any contractual or other commitment binding upon Rolls-Royce plc or any of its subsidiary or associated companies. The Comparator Tool

Rolls-Royce data Assumption The engineering practice of translating requirements into a implementation will be “similar” in many engineering domains and will be subject to the same cost drives as software 6

Rolls-Royce data Cost = C * Size * Environment Size Environment Higher Cost Lower Cost Size (the product): The magnitude (or quantity) of a task. Size Complexity Reuse Risk/Uncertainty Environment: The environment in which you build the product Processes & tools People Management Organisation Etc 7

Rolls-Royce data 8 Comparator Tool Historic Baseline Historic Size Historic Environment (a definition of the project environment) Actual historic cost New Project New Size New Environment (a definition of the project environment) Delta Create a scaling Factor that represents the differences between the two projects in both size and environment New cost = Historic cost * Delta

Rolls-Royce data 9 Examples

Rolls-Royce data 10 Absolute Tool New Project Size (task and unit) Environment (a definition of the project environment) cost = Standard Job * Size * Environment Standard job hours An “Absolute” estimation tool was developed for Hardware by relating hardware complexity to software lines of code. This relationship is hidden from the estimator who only has to select hardware units they are working on

©2011 Rolls-Royce plc The information in this document is the property of Rolls-Royce plc and may not be copied or communicated to a third party, or used for any purpose other than that for which it is supplied without the express written consent of Rolls-Royce plc. This information is given in good faith based upon the latest information available to Rolls-Royce plc, no warranty or representation is given concerning such information, which must not be taken as establishing any contractual or other commitment binding upon Rolls-Royce plc or any of its subsidiary or associated companies. Calibrating a Whole Engine R&D Cost Model

Rolls-Royce data Abstract Business Challenge Can we use COCOMO to estimate the cost of a whole engine? Effort We have 8 hours to demonstrate this capability! Approach Use Comparator method based on COCOMO II Relate all aspects to a nominal “Baseline” project COCOMO II factors to be completed by Chief Design Engineer No underlying factors to be altered – only the constant “C” Leave 1 project aside as a test of calibration (project 6) 12

Rolls-Royce data 13 Environment: Relative (COCOMO II factors) High requirements volatility, low TRL, low process maturity, low team experience, low management experience and high schedule pressure High Schedule pressure Some architectural issues. Drop in team experience, high turnover of staff, multi site working Requirements change, loss of precedence, inexperienced team, architectural issues, loss of team cohesion, schedule pressure, new management team, multi site project, staff turnover Loss of precedence, some architectural issues, schedule pressure, multi site project, high staff turnover Engine 1Engine 2 Engine 3Engine 4Engine 5Engine 6 The only show in town – high priority. Single site project, stable team Stable requirements, higher precedence, team more experienced, single site team, improved process maturity., high levels of reuse Stable requirements, higher precedence, single site team, improved process maturity. Improved management High process maturity, Lower requirements change, team cohesion, process maturity, experienced team Low requirements volatility, high team cohesion, high precedence, mature processes, experienced team, low schedule pressure, experienced management team

Rolls-Royce data What correlated well Size REVL PREC FLEX RESL TEAM PMAT SCED Management Expereince Based on the survey, these factors correlated well with cost. This does not mean the other factors do not – rather it means that these were the factors the interviewee understood well. 14

Rolls-Royce data 15 Predicted & Actual costs – A close correlation Baseline Calibrate to these projects Estimate this project

Rolls-Royce data Cost = C * Size * Environment Size (AMF) – not to scaleEnvironment (not to scale) B

Rolls-Royce data Conclusions Size is not the only determining factor for cost – the environment is also proving critical for project success. From a simple analysis, it would seem that COCOMO II can be used to “model” the development environment The Rolls-Royce Environment is changing and COCOMO II predicts that this is creating a headwind The exercise has the side effect of training the business leaders in the factors that affect cost 17

©2011 Rolls-Royce plc The information in this document is the property of Rolls-Royce plc and may not be copied or communicated to a third party, or used for any purpose other than that for which it is supplied without the express written consent of Rolls-Royce plc. This information is given in good faith based upon the latest information available to Rolls-Royce plc, no warranty or representation is given concerning such information, which must not be taken as establishing any contractual or other commitment binding upon Rolls-Royce plc or any of its subsidiary or associated companies. Why Estimation Tools Help the Business

Rolls-Royce data COCOMO II: A common Language COCOMO II is a language that bridges between engineering and the business It is also the bridge between different areas of the business It has been used to help benchmark the business 19

Rolls-Royce data Remain within a domain You can interpolate and extrapolate within a domain but not across domains (unless you have a domain bridge function) COCOMO II appears to work on engineering practices where requirements are translated into implementation through an engineering process 20