Measuring Technological Change

Estimates turbine engine parameter trade-offs over time, using multiple regression analysis. Movement of the parameter trade-off curve is defined as technological advance. The database includes the first model of a given turbine engine to pass the Model Qualification Test. The history of turbine engines strongly suggests that single parameter analysis cannot capture the richness of the development process. The rate of technological advance seems fairly constant over time. However, two major manufacturers have been ahead of the others in the level of technology. Turboprops did exhibit a different technology from turbofans and turbojets. In 9 out of 10 cases, the rate of increase of technology of growth versions of engines was less than the average trend of technology for new engines, indicating that when design features become hardware, technology growth cannot take full advantage of new techniques. Comparison of Soviet and American equations revealed an early Soviet lead, reversed since the 1950s.