By John Keller
ST. LOUIS - Avionics experts from McDonnell Douglas Corp. are ready to move an important experimental software architecture out of the laboratory and into operational aircraft. This new approach to software engineering makes it possible for developers to use the same software applications across a diverse range of tactical aircraft.
McDonnell Douglas Aerospace engineers in St. Louis have demonstrated the architecture, called the Common Operational Flight Program (OFP), in the AV-8B jump jet, F-15 jet fighter, and F/A-18 fighter-bomber, and plan to extend the architecture`s use to the C-17 airlifter and AH-64 attack helicopter, says Don Winter, the OFP project manager.
"We are making the transition from proof of concept to implementation," Winter says. "We have proven that software reuse across diverse aircraft programs is viable."
The first real-world use of the OFP will be in the Open Systems Core Avionics Requirements (OSCAR) program to upgrade the mission computer of the AV-8B from the current AN/AYK-14 Navy standard airborne computer to a new system based on the IBM/Motorola PowerPC microprocessor, Winter says.
McDonnell Douglas received a Navy contract to upgrade the flight computers in the U.S. inventory of AV-8B aircraft last October. Engineers from Computing Devices International in Minneapolis will build the computer, and McDonnell Douglas software engineers will write all the code for OSCAR.
"The government will acquire these [OFP] assets for the first time under the OSCAR program, and could make it available to other developers," Winter says.
He cautions, however, that company and government officials still must work out some of the intellectual property issues before they make the OFP technology available to companies that might want to turn it into a commercial offering. The OFP has some off-the-shelf third-party technology, such as the VX Works real-time kernel from Wind River Systems in Alameda, Calif.
The OFP, which began in late 1995, first focused on developing generic navigational flight software in the C++ programming language. Winter and his staff ran the software in PowerPC-based flight computers on an AV-8B in March 1996 and on an F-15 in May 1996. In September 1996 they flight tested the same software on a MIPS R4400-based computer aboard an F/A-18 jet.
Now Winter and other company experts are flight testing weapons-control software written in the Ada 95 programming language on the PowerPC-based computer on an AV-8B. This software performs all release calculations for accurately dropping gravity bombs.
One primary objective of the latest test flight "is to show inherent capability for our architecture to support mixed languages," Winter explains. "The air-to-ground application, developed in Ada 95, will co-exist with the C++ navigation module for this demonstration."
The navigation module is 3,000 lines of C++ code, and the bomb-control module is 5,000 lines of Ada 95 code, Winter says. Company engineers used the Rose software engineering environment from Rational Software Corp. of Santa Clara, Calif., for the navigation module, and used the MULTI software engineering environment and cross compiler from Green Hills Software Inc. of Santa Barbara, Calif., for the bomb-control module.
A central thrust of the OFP is creating a hardware-independent software architecture, Winter says. "In our layered architecture, the objective is to isolate code at the application level from the peculiarities of the hardware at the bottom - from the processor and even the bus topology," he explains. Application program interfaces in the OFP include the POSIX operating system interface and the Common Object Request Broker Architecture, better known as CORBA.
Overall, Winter says the OFP should help avionics developers stop re-inventing the wheel when they add capabilities to different aircraft, such as the Joint Direct Attack Munition (JDAM).
"We should be able to take the [JDAM] AV-8B component and use it on the F-15 and F/A-18," Winter says. "Historically we were organized in program silos. We would have implemented JDAM separately for all three aircraft. We would have had little synergism, and the government would have paid for it three times."
Although there are no firm plans to migrate the OFP architecture to civil aircraft, Winter says it has potential for commercial airliners. He says he has explained the architecture to officials of the Requirements and Technical Concepts for Aviation group in Washington, better known as RTCA, "so there has been some interchange," he says.