The Reliability of Six 9s,or 99.9999% - Founded on NASA Techniques and Constant Effort
A platform car carrying a test dummy begins moving, quickly reaching a speed of 30 miles (48 kilometers) per hour as a small crowd of staff people watch in eager anticipation. Then comes the moment, with a thunderous "Bang!" The onlookers could see the dummy sway in its seat; moreover, the impact was so great that even those standing at a distance could feel it.
"Okay," someone says, affecting a tone of confidence. "We must have done it right this time." However, that person's hopes are quickly shattered when it is found the dummy had plunged forward before the airbag inflated.
It was always the same: They could not seem to inflate the bag within the target space of time. Of course, that particular window was only a fraction of a second, 0.003 sec. to be exact. The development staff had already experienced this failure a great number of times. Every test started with the highest hopes, only to end in disappointment as the test staff realized they had not achieved the correct timing for inflation. However, no one had the luxury of feeling down about it. They knew that if they couldn't leap this hurdle, no one could.
The year was 1975, and Honda had just begun an independent development project for an airbag system. One day Motohiro Okada, manager of the project, handed a notebook to Kiyoshi Honda (no relation to Soichiro Honda), a member of the development team. "Read this information," Okada said. But the book was nearly empty, except for a single remark about a test procedure designed to measure the sound of a "bang"; the sound an airbag makes at the instant of inflation. Since they had no development partner to rely upon, the staff had to start by groping in the dark for any available clue.
It seemed the moment was right for Honda to develop an airbag system. Ever since a 1970 review by the United States Congress there had been ongoing debates as to whether the automakers should be required to equip their passenger cars with passive restraint systems. Such systems would have included passive seatbelts, airbags and other devices that don't require an intentional action by the user in order to be deployed. Ford and GM had already carried out fleet tests in 1972 and 1973, respectively, and it was simply no longer possible to sell cars to the consuming public while claiming to the authorities that safety was a hindrance to production and marketing.
Honda, in order to develop its own airbag system, had decided to employ the "concurrent implementation of heterogeneous projects." Specifically, two teams would be formed, competing against one another with independently contrived airbag mechanisms. In Honda's case, one was based on an outside-air induction system, while the other relied solely on a charge of gas. Although both types had cleared the first hurdle with sufficient amounts of inflation, the gas-only system was ultimately chosen due to its simpler mechanism.
A gas-only dual-airbag configuration covering both the driver and front passenger. The system is linked to a 1500 cc cylinder filled with gas compressed to 400 barometric pressures.
According to the results of their crash tests, the team decided they had to increase the efficiency of gas blow-out. Therefore, the gas cylinder's pressure setting was increased to 400 barometric pressures. At that level, whatever knowledge they had would no longer apply. The staff had to think for themselves and try out each idea on their own.
"The creation of a new technology means there's no one else who has the information you want," said Kiyoshi. Honda. "We could consult experts in related fields, but to put all the pieces together in a complete system was another thing entirely."
The journey was an ongoing succession of obstacles. So, whenever the development staff hit a wall, they would go to experts in the field and learn from them. They would correct drawings, and often weld parts and work sheet metal themselves. Through these efforts, the crash speed gradually increased to 35 miles per hour. At the third evaluation meeting held in January 1979, the team finally succeeded in inflating the bag in time.