Evolution of Piston-Engine Fighter Aircrafts: Cluster Analysis to Study the History of Technology. Part 2

Abstract

The article carries out cluster analysis of serial piston-engine fighters. 672 modifications built in 26 countries from 1913 to 1951 are taken into account. Maximum speed, wing load, power load and weight ratio are chosen as coordinates. Clustering reveals pioneering design: the earliest models in each cluster. One can also measure the dynamics of ideas lifetime that is the period when similar aircrafts (those within one cluster) were manufactured following the same methodology. The frequency new clusters emerged demonstrates the speed of technological progress. The author has found the turning points of development. These are 1930 and 1935. Until 1930 flight characteristics were increasing both due to an increase in thrust-to-weight ratio and an increase of wing load. Later the thrust-to-weight ratio remains practically unchanged. In 1935 the first aircraft appeared from three of the 19 clusters at once. Among them are the little-known Yugoslav fighter Ikarus IK-2 and the Soviet I-16 Type 5. The change of leading countries and the lifetime of ideas have been studied as well. The interval between the manufacture of the first and the last model, related to the cluster, corresponds to the time period when designers followed the same approach when designing an aircraft. Between wars, this interval exceeded 10 years whereas during rapid development periods it was 5-6 years shorter.