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Digitool's History

Coral Software was formed in 1985 to develop a high-quality Common Lisp development environment for Macintosh computers. Coral's flagship product, Coral Common Lisp, became an overnight sensation among professional Lisp programmers and Macintosh enthusiasts.

Apple Computer adopted Coral Common Lisp in its research and development organizations for some very ambitious projects, including Apple Dylan, a full-featured IDE, compiler, and application framework for the Dylan programming language. Apple's heavy involvement in Lisp programming led it to acquire Coral software in 1989.

Apple changed the name to Macintosh Common Lisp and continued to develop and improve the product, including release of a major upgrade to bring the implementation into line with the 1990 second edition of "Common Lisp: The Language."

Later, Apple decimated its Developer Tools Group and stopped development of many of its IDE and compiler products, including Macintosh Common Lisp. Despite this setback, programmers worldwide continued to develop leading-edge software technology using Apple's Lisp, which was regarded as superior to competitive products still in active development.

Apple Computer licensed Macintosh Common Lisp to Digitool on November 10, 1994. Digitool was founded to develop and market Macintosh Common Lisp, with financial backing from eleven corporate sponsors and staffed by many of the original developers of Coral Common Lisp and Macintosh Common Lisp.

Digitool's first objective was to port Macintosh Common Lisp to run native on Power Macintosh (PPC) computers. This was a major effort involving a complete rewrite of the compiler and the Lisp kernel. Along the way, Digitool developed a common code base for the IDE and library of its 68K and PPC versions of Macintosh Common Lisp and added support for WorldScript and lightweight Lisp processes. Digitool released the 68K version of this major upgrade in May 1995, and the first PPC version in April 1996.

Digitool continues to support and improve Macintosh Common Lisp, releasing compatible 68K and PPC versions every four to six months.

Digitool's founding sponsors are companies, universities and individuals with a strong belief in Common Lisp and a solid commitment to its success on the Macintosh and the PowerPC. Founding sponsors benefit in a number of ways from the early association with Digitool's MCL development effort. These include early access to the MCL PowerPC technology and closer coordination of related development activities.

Opportunities exist for additional sponsors to support MCL and to garner similar benefits. Contact Digitool for information about becoming an MCL sponsor.

Apple Computer, Inc.
We all know who Apple is, but did you know they once had a Cambridge Developer Group? Though no longer in existence, they were forging new ground with Dylan, and MCL was helping to pave the way.

Flavors Technology, Inc.
Flavors Technology, Inc. sells hardware and software tools for massively parallel real-time control, scheduling, and simulation. Our customers include major corporations involved in manufacturing, transportation, utilities, and semiconductor fabrication. These customers are using our unique tools and techniques to solve very difficult problems. Our parallel programming language, Paracell, is used to construct these multi-agent simulation and control systems. Flavors has also been involved in a few ARPA contracts to study the application of our approach to job shop and process scheduling and simulation, materials and requirements planning, and battle management.
For additional information, contact:

Doug Currie, VP, Engineering, Flavors Technology, Inc., 670 N. Commercial Street, Manchester, NH 03101-1149
Tel: 603-647-1270, Fax: 603-647-6180, Data: 603-647-6380
E-mail: e@flavors.com

Lissys Ltd.
Lissys Limited is the developer of PIANO, an MCL-based system for Commercial Aircraft Project Design and Competitive Analysis. PIANO can analyse aerodynamics, weights and performance characteristics of commercial aircraft. The package includes a reference database of more than 100 current and projected aircraft and is in use with many international aerospace companies including AIRBUS Industry, Rolls-Royce plc and De Havilland Inc.

A design desktop option

The art of evaluating the characteristics of both existing and projected aircraft is critical for competitiveness and success. A novel software package called PIANO bridges the gulf between back-of-the-envelope guesses and multi-million-dollar, year-long studies.

Every new aircraft that appears in the market is compared with other designs and analysed by its makers, its competitors and its potential customers. Future options are examined in the context of any aircraft which are currently available and the alternatives which other manufactures are contemplating. And yet, strategy, marketing, design and acquisition analysts rarely have any common reference points around which to coordinate their actions.

Vast amounts of information must be processed when a competitive evaluation takes place. Although experience and instinct are key factors in reaching correct decisions, they do not function in a vacuum. Exhaustive evaluations of mass, aerodynamics, payload-range capabilities, field performance, altitude capabilities etc. must be undertaken by computers. Thankfully, the complexity of this task can now be handled at a much higher and more accessible level than ever before. PIANO is a software tool which provides such powerful new resources directly on the desk of the decision makers. It offers a widely-used, consistent and common reference platform around which judgments can be made with confidence. A number of major Aerospace Companies such as AIRBUS, Allison GM, BMW-RR, De Havilland, Rolls-Royce and SNECMA are already using the system for a variety of purposes.

System Architecture

The PIANO system has a number of key features:

• Reference designs covering a broad spectrum of both existing and projected competing aircraft.
• The ability to very quickly create and analyse new designs.
• The ability to examine growth potential or other future modification options including family strategies.
• Extensive parametric study and optimisation facilities.
• Interactive, high-level handling of all of the above tasks.
• Productivity from the first day after system installation.

These capabilities could not have been achieved without adopting a radically new approach. The hardware platform selected at the beginning of system development, approximately six years ago, was the Apple Macintosh personal computer. PIANO has taken full advantage of its unique user-friendly window-based interface in order to intuitively handle some very complex tasks. Rapid increases in processing power have meant that PIANO can now run even on laptop or notebook computers (i.e. the Macintosh Powerbook) and yet rival performance levels only available in the mainframes of some years ago. At a deeper level, which is entirely transparent to the user, the code has been developed around the advanced Macintosh Common Lisp (MCL) language. This proved to be a perfect vehicle for complex software delivery. It offers object-oriented features and many dynamic programming facilities which were instrumental in keeping track of the approximately 2 Megabytes of source code which currently form PIANO. This code embodies more than a decade of Aerospace design and consultancy experience.

Easy interaction

Using PIANO, individual aircraft or 'point designs' can be modelled from scratch within some tens of minutes. Only 20 fundamental parameters (such as wing area, aspect ratio, sweep, thrust, gross weight etc.) need to be initially supplied for the purposes of a basic definition. A total of approximately 200 design parameters are available if required for detail refinement. These parameters can be input and modified in any order, with the system keeping track of consistency requirements. All features of the system can be accessed through menus and dialogs and include on-line self-documentation and automatic search facilities.

Designs are stored in compact files which retain only the fundamental defining parameters. The full characteristics of each design are then automatically re-created when such files are loaded back in. For practical purposes, an unlimited number of such designs can be stored. Factors and adjustments are available allowing the user to fine-tune or override internal calculations in order to match external data.

Engine characteristics are kept in separate files. They consist of thrust rating structures (takeoff, max. climb, max. cruise, and max. continuous) as well as fuel consumption characteristics and are modelled in the form of data matrices. Such 'rubber' engines can be scaled to any thrust, plotted and modified. New engines can be added to the database independently of the aircraft.

Geometry, mass and balance calculations are carried out when required to arrive at a self-consistent design. The system will determine the values of Operating Empty Weight (OEW) which correspond to any specified values of Maximum Takeoff Weight (MTOW). Automatic iteration options permit determination of the MTOW required to match specific Payload-Range capabilities. Adjustments can also be introduced to match precisely known (or claimed) values of OEW. All internal mass estimations are based on industrially-derived methods and have been calibrated against a large database of real aircraft data which are not generally available in the public domain.

Aerodynamics are evaluated on the basis of aircraft geometry and technology levels. Complete Lift-Drag polar plots, tabulations, or itemised drag component contributions can be produced. The calculations of zero-lift, induced, and compressibility contributions are built up using classical preliminary design methods and reflect all major effects of varying wetted areas, sweep, aspect ratio, thickness/chord ratios, etc.

It is possible to evaluate Payload-Range performance and altitude capabilities at any number of flight conditions, including off-design operations. A large choice of operating Mach/Altitude modes are available for range estimation. Field performance is estimated at arbitrary field elevation and Delta-I.S.A. conditions and can be adjusted to match external data. Direct Operating Cost is also estimated.

Usage and applicability

PIANO is geared around JAR-25 type conventional subsonic commercial aircraft. It has been successfully used to evaluate aircraft ranging in size from very small business jets (such as the Swearingen SJ30) to aircraft larger than the Boeing 747-400, such as projected 600 or 800 passenger ultra-high capacity aircraft.

The current aircraft database consists of approximately 100 sample designs. Data have been collected from a variety of sources and are constantly being updated. Although it is not always possible to precisely match existing designs in terms of the manufacturers' claimed performance, any adjustments needed to do so are generally minor. The fundamental design characteristics are well reflected and can be used as a basis on which to carry out studies. By using common methodologies and modelling algorithms, it is also possible to ensure a consistent basis for comparison. This is particularly important since brochure data and claimed characteristics are rarely supplied by different manufacturers in a uniform format which permits such comparisons.

Joint studies based on PIANO have recently been undertaken between airframe and engine manufacturers to evaluate a number of potential baseline ultra-high capacity designs and family concepts. Growth potential is particularly important when developing completely new designs. Over the past decade, many aircraft were sized to specific mission requirements and tightly optimised around them. It is possible however that such over-optimisation can adversely affect the ability to grow or shrink a design to meet new market needs. The effects of de-optimisation of a design can be easily demonstrated by PIANO. New large aircraft entering the marketplace must be able to eventually grow in MTOW and seating capacity, possibly up to 1000 passengers plus. The wing selected must be adequate for the task without requiring major redesign and without noticeably de-optimising the initial versions. Engine options have been examined in terms of likely new powerplants. Many open questions still remain regarding the numbers and types of engines. The impact of selecting existing thrust classes or relying on the growth of high-thrust engines currently under development for EROPS-certificated large twins must also be considered.

PIANO has also been used to examine other classes of aircraft such as the new generation of global-reach business jets. It has clearly shown the critical importance of technology assumptions in such aircraft. The quality of aerodynamic and structural development of these aircraft will need to improve and match the best practices of large commercial aircraft design if success is to be achieved.

Turning to existing aircraft, PIANO can help to show the improvements possible through standard developments such as re-winging, adding fuselage plugs and re-engining. Although some of the detail of such exercises is beyond the scope of preliminary design, the major effects of gross modifications can be anticipated for competitive evaluation purposes.

Utilities

In addition to its extensive analysis capabilities, PIANO bundles together a number of utilities which are useful in the normal everyday work of designers and analysts, such as airspeed conversions, atmospheric data and an expandable database of international airports and great circle distances.

Many tasks which previously required expensive mainframe hardware and supporting resources can now be handled directly through PIANO at the desks of the most appropriate design and evaluation personnel. This tightening of the design and analysis process is a significant step towards quick, effective and consistent decision making.

For additional information, contact:
Dr. Dimitri Simos
Lissys Ltd.
6 Paterson Drive, Woodhouse Eaves, LE 12 8RL
United Kingdom
E-mail: dim@lissys.demon.co.uk

University of Basel, Switzerland

Yaskawa Electric, Japan
Yaskawa Electric Corporation is a manufacturing company of industrial electrical and electronic equipment and systems since 1915. It has a strategic plan to get into industrial and non-industrial information technology and business. One of those new products is the user of LISP. The company size is 4500 employees and $1.3 B annual sales including industrial robots known as Motoman.
For additional information, contact:

Seiichi Yaskawa, Information Business Development, Yaskawa Electric Corp.
Tel: +81-3-3284-9103, Fax: +81-3-3284-9303
E-mail: 101132.2601@compuserve.com

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MCL and Macintosh Common Lisp are trademarks of Digitool, Inc. Apple, the Apple logo, and Macintosh are trademarks of Apple Computer. All other trademarks mentioned herein belong to their respective owners. Last update: Sat, Mar 06 1999 at 16:32:48