Westland Helicopters is an AgustaWestland Company

21 ISMOR Norton Manor: 31st August - 3rd September 2004 The Need For And Value Of Simple OA Models In Industry

Westland Helicopters is an AgustaWestland Company OA at Westland Helicopters (WHL) OA Modelling at WHL Complex and Simple Models Abuse - Potential for Misuse of Simple Models –Example Summary

Westland Helicopters is an AgustaWestland Company OA at Westland Helicopters (WHL)

Westland Helicopters is an AgustaWestland Company The industry is: AgustaWestland: Therefore: Aerospace Helicopters, Small OA team. WHL OA

Westland Helicopters is an AgustaWestland Company WHL OA Role of OA in WHL is: Having a deeper understanding of operational needs.

Westland Helicopters is an AgustaWestland Company WHL OA Matching potential products and technology to these operational needs.

Westland Helicopters is an AgustaWestland Company OA is often a ‘bridging’ activity, between: –the customer community –‘core’ engineering activities. WHL OA

Westland Helicopters is an AgustaWestland Company WHL OA Assessing strengths / weaknesses of competitor products.

Westland Helicopters is an AgustaWestland Company WHL OA OA at WHL is within the engineering organisation; this is because: –It is an objective analytical discipline –It requires sound knowledge of the product’s technology and performance –It needs to understand future technologies and their potential for capability enhancement –It retains its credibility.

Westland Helicopters is an AgustaWestland Company WHL OA In practice: We are often working within tight time constraints And explaining the work and results to non OA specialists.

Westland Helicopters is an AgustaWestland Company OA at Westland Helicopters (WHL) OA Modelling at WHL

Westland Helicopters is an AgustaWestland Company WHL OA - Modelling There are very detailed and complex models of aircraft and systems within engineering and the rest of the company, We use the results of these as data sources OA modelling at aggregated level above these.

Westland Helicopters is an AgustaWestland Company WHL OA - Modelling We’re interested in aircraft in operational settings.

Westland Helicopters is an AgustaWestland Company WHL OA Modelling Complex Engineering Models Aircraft DataScenario Data OA MODELS Customer Requirements Relatively Simple

Westland Helicopters is an AgustaWestland Company WHL OA Modelling Some of the things WHL OA models address: Support Helicopter Fleet lift & availability –Single or several helicopter types –Single or multiple tasks –Short or long operational periods –Amphibious or land-based Sortie flying hours analysis for amphibious forces Ship operations Aircraft survivability Capability assessment –Support helicopters –Light utility helicopters –Attack helicopters.

Westland Helicopters is an AgustaWestland Company WHL OA - Modelling Why do we use simple models? What is a simple model? Conversely, what isn’t?

Westland Helicopters is an AgustaWestland Company OA at Westland Helicopters (WHL) OA Modelling at WHL Complex and Simple Models

Westland Helicopters is an AgustaWestland Company Complex Models If not Simple, then a Complex model: –Large (lines of code) –Lot of input data –Involves wide range of aspects.

Westland Helicopters is an AgustaWestland Company Complex Models Drawbacks: Advantages: –Takes time to collect data –Takes time to set up –May not be easily understood; can be rather a “black box” –Requires a great deal of documentation –High development costs in time & effort before can use –High cost of further development, –Models details –Copes with interactions of many systems –Variety of output.

Westland Helicopters is an AgustaWestland Company Simple Models Simple models: –Simple enough to develop or tailor for a particular problem –Fast enough to provide a quick turnround of results –Transparent enough for ready understanding. –Small (lines of code) - small enough to operate on a PC –Limited input data –Limited number of aspects

Westland Helicopters is an AgustaWestland Company Simple Models Drawbacks: Advantages: –Model few details or is high level –Limited number systems –Limited output, –Relatively easy to collect data –Quick to set up –Easily understood; “transparent” - fairly easily assimilated –Requires limited documentation –Can be tailored relatively cheaply / easily.

Westland Helicopters is an AgustaWestland Company WHL OA - Modelling: Simple Models Benefits for WHL OA of using simple models: Easier to set up and run Easier to explain Easier to maintain So we need simple models.

Westland Helicopters is an AgustaWestland Company OA at Westland Helicopters (WHL) OA Modelling at WHL Complex and Simple Models Abuse - Potential for Misuse of Simple Models

Westland Helicopters is an AgustaWestland Company Abuse of Simple Models But there is potential for abuse: –They may think it does what it cannot Customers may think there’s more in a simple model than there really is: –They may have too much faith in the results (nobody reads the caveats).

Westland Helicopters is an AgustaWestland Company Such as compare apples with pears... & lemons, pineapples, bananas, strawberries, … Or customers may want to bend models to do what they cannot. Abuse of Simple Models

Westland Helicopters is an AgustaWestland Company Abuse of Simple Models Or introduce details that may add realism, but are not really necessary.

Westland Helicopters is an AgustaWestland Company Customers may think they understand it enough to want to take it and use it themselves: –It may be a simple model to a specialist –But in the wrong hands, it may not be recognized for what it really is. Abuse of Simple Models This is particularly true of soft OA tools.

Westland Helicopters is an AgustaWestland Company OA at Westland Helicopters (WHL) OA Modelling at WHL Complex and Simple Models Abuse - Potential for Misuse of Simple Models –Example

Westland Helicopters is an AgustaWestland Company Example Target Scores (Requirements ) One example is an MCDA tool that we use:

Westland Helicopters is an AgustaWestland Company Example Target Scores (Requirements ) Aircraft Scores (Capabilities ) One example is an MCDA tool that we use:

Westland Helicopters is an AgustaWestland Company Example Target Scores (Requirements ) Aircraft Scores (Capabilities ) Comparison: Aircraft Scores minus Target Scores One example is an MCDA tool that we use:

Westland Helicopters is an AgustaWestland Company Example Each characteristic is represented by a 5 level scale e.g. Troop Capacity: (No. of troops carried in crashworthy seats) Level 1 = <2 Level 2 = 2-3 Level 3 = 4-5 Level 4 = 6-7 Level 5 = Over 7.

Westland Helicopters is an AgustaWestland Company Advantages: Example - Advantages One can use hard and/or soft data It permits comparisons of different aircraft / system configurations or types. It allows one to address diverse problems,

Westland Helicopters is an AgustaWestland Company Drawbacks: Example - Drawbacks (1) –The scoring scales must be representative of the problem being examined e.g. Troop Capacity scale shown may be unsuitable for large lift operations. The scoring process must be set up very carefully –Steps must have similar impact e.g. Troop Capacity: Level 1 = <2<2 Level 2 = 2-32 Level 3 = Level 4 = 6-77 Level 5 = Over 7>7,

Westland Helicopters is an AgustaWestland Company Example The user must be aware of any potential interdependencies –e.g. Payload / Range could be separated, but interdependency makes it difficult. –Hence, combine them, supported by lower level modelling The user must be aware of any potential conflict. –e.g. Payload / Range and Troop Capacity. Example - Drawbacks (2)

Westland Helicopters is an AgustaWestland Company Example Aggregation needs to be handled with care (if at all) –Could: Take worst of a set of results (sometimes useful) Accumulate negative scores (no credit for overachieving) Must capture and record all: –Assumptions –Judgements –Reasoning. Example - Drawbacks (3)

Westland Helicopters is an AgustaWestland Company This is a lot to expect of a “naïve” user - who may not appreciate these subtleties. Abuse of Simple Models

Westland Helicopters is an AgustaWestland Company Some things are best left in the hands of specialists. Abuse of Simple Models

Westland Helicopters is an AgustaWestland Company OA at Westland Helicopters (WHL) OA Modelling at WHL Complex and Simple Models Abuse - Potential for Misuse of Simple Models –Example Summary

Westland Helicopters is an AgustaWestland Company In Summary At WHL we use a range of modelling techniques in support of the company, underpinned by more complex models We need relatively simple models because they are: –Easier to use –Easier to explain –Easier to maintain There is always potential for these models to be abused, and we need to guard against this. Summary

Westland Helicopters is an AgustaWestland Company