Designing the 777

Commercial aircraft design is no mean task. Spread over many years, many teams and many locations, the effort utilizes a variety of computing resources to deliver the goods. We look behind the scenes at one of the biggest design projects of all times

When the Boeing 777 came out in 1995, it had many firsts to its credit. The most significant of these, in our context, is that it was the first jetliner to be completely digitally designed. Traditionally, aircraft were designed on 2D CAD software, and during design, various scale mockups (including full-scale mockups) were created to ensure that all the parts fit properly. In the 777, all such testing was simulated inside computers, using 3D CAD solutions.

The design software used was Dassault Systèmes’ CATIA (Computer Aided Three Dimensional Interactive System) CAD/CAM design environment. Such 3D software can automatically identify the physical proximity of components, that is, how well and closely they fit. And, when the first plane was finally assembled, the error margin of parts fitting was apparently just 0.23 inches, as against the traditional 0.5 inches when design was done with mockups.

Designing a new aircraft of this scale is no mean job. The design of the 777 took about ten thousand people in 238 build teams across many companies and continents. The network that connected them obviously also had to span continents. The data transferred on this network during the design phase alone amounted to 1848 GB! This network had a variety of hardware, including eight Mainframes, in the US and Japan. The basic CAD software was enhanced using custom-created add-ons for data management, visualization and general user productivity. 

It is not just in designing the aircraft that computers come into play. There is a lot of computing power and software built into the aircraft itself. The 777 is a fly-by-wire aircraft. That is, instead of using wires to move the elevator, rudder and ailerons to control the aircraft, the 777 transmits the actions of the pilot as electric signals to the primary flight computer, which in turn controls the flight. So, the cockpit with all its LED displays and touch keypads is more of a computer network operations center than a traditional flight deck.

That brought up an interesting problem. In traditional wired systems, when the pilot operates the controls, he feels the resistance to the movement, much like a car driver feels the car respond to his actions. With fly-by-wire controls, there is no such mechanical response. So, to make the pilots more comfortable, motors have been built into the controls that do nothing but provide the traditional wired feedback; this is akin to the force-feedback mechanism built into gaming controls! 



Coming back to the computing systems in the 777, most of the code for the 777 is written in Ada. Different companies have developed different sub systems for the aircraft, all in Ada. Honeywell did the primary flight controls, Hydro-Aire did the brake-control system, while Sunstrand (Thomson Software Products) did the electrical power systems, and so on. 

The primary flight controls are made up of an airplane information-management system and an air/data inertial reference system. The airplane information-management system runs on the largest central computer onboard the aircraft, a multiprocessor and a rack-mounted system. This system, based on the AMD 29050 processor, is built along the lines of a Mainframe, with different functions running on the same machine, instead of on different systems, and with each function being guaranteed its CPU timeslot.

The systems disk drives can read MSDOS formatted disks. What for? The system also incorporates central maintenance.

That is, it collects information from other computers onboard and collates a maintenance report. This maintenance report can be copied out by the maintenance department that is using these drives. 

Like with any other good software projects, large parts of the code written for the 777

have been reused in other aircraft projects, both civilian and military.

As we said in the beginning, the project used eight Mainframes. Remember that that is just for one project. Boeing uses many supercomputers to design its aircraft, rockets and satellites. Current trends have been moving to clustered systems. Boeing’s most powerful supercomputer comes in at number 307 in the list of the 500 most powerful supercomputers in the world. This is based on the IBM P-series 690 turbo. In 2001, they had purchased four clustered supercomputers running Linux.

But computers as yet cannot simulate everything when designing an aircraft. For example, they cannot do the dead chicken test. Now, what is that? Many tests are done to prove the engines of a new aircraft. One of them is to fire an eight-pound, dead chicken from an air cannon onto a running engine. This is to simulate a largish bird being sucked up into the engine while in flight. Computers are not doing that test, yet.

Krishna Kumar