Production and development of four-seat airplanes in the XX century. Statistical analysis

Kuzmin Yurii Viktorovich PhD in Physics and Mathematics Senior researcher, S.I.Vavilov Institute for the History of Science and Technology, RAS 125315, Russia, g. Moscow, ul. Baltiiskaya, 14 ykuzmin@rambler.ru Other publications by this author

Introduction

The article studies the history of production and development of an important segment of aircraft construction of the XX century – four-seat civil aircraft.

For the first time in the world, consolidated data on the production of four-seat aircraft and the number of their models, broken down by country and design features, have been collected.

It shows how many planes, when, in which countries and by which companies were built. As far as I know, such summary data has never been published. It was studied how the demand for aircraft of this class changed, did the intensity of development correlate with this?

Based on the collected data, it is proved that developers and business owners, in general, respond adequately to market growth, but inadequately to its decline. Instead of adaptation, cost reduction, there is an "agonistic" reaction – disorderly activity, an increase in the volume of design work during a decline in sales, attempts to improve the quality of the proposed product despite the increase in cost, and even attempts to occupy neighboring markets.

To identify the described reaction, the method of calculating the sliding correlation of series describing the release and development of new aircraft models was used.

In the second part of the article, the technical evolution of four-seat aircraft during the XX century will be considered.

Problem statement

During the XX century, airplanes have changed a lot. Their speed has increased tenfold, their mass has increased by hundreds, and the power of power plants has often increased by thousands. Graphs in articles and books on the history of aviation either take off exponentially, or have a pronounced form of an integral curve, the values of the lower and upper asymptotes of which differ at times, if not by orders of magnitude.

For example, the speed of the first fighters was just over 100 km/h, and in recent decades it has stabilized (with some exceptions) at the level of 2000-2500 km/h. The growth of the most important indicator by one and a half orders of magnitude was achieved in just half a century.

At the same time, it is not taken into account that the requirements for aircraft themselves change over time. Cargo and passenger traffic are growing sharply in the civilian area, which requires more spacious aircraft. The globalization of the economy, the emergence of new development centers lead to an increase in the range of transportation. If between the World Wars the busiest international route was the route across the North Atlantic, now an increasing proportion of passengers need to cross the Pacific Ocean.

The growth in traffic volume has made it profitable to invest heavily in infrastructure – the construction of airports with long and strong runways. And this weakened the requirements for the take-off and landing characteristics of civil aircraft.

The military area feeds itself. If a potential opponent has faster ones (for example) aircraft, then this means that during the fighting he will impose the initiative: choose when to take the fight, when to dodge it. Therefore, the aircraft being created should fly even faster. The development of military equipment, unlike civilian technology, is a process of continuous competition with constant overcoming of physical and economic barriers.

So, in both the civil and military industries, rapid progress, expressed, among other things, in the growth of the main indicators (masses, sizes, absolute and specific capacities, wing loads, range, altitude, etc.) at times, or even more than an order of magnitude, is natural and has its own internal logic.

Sometimes such growth can be stopped by a psychological, physical economic barrier, and more often by their combined action. So, for most passengers, it is not so important whether they will fly to another hemisphere in six hours or fifteen, since such trips are relatively rare and are not planned in one day. On the other hand, air resistance at supersonic speeds increases dramatically, aerodynamic quality decreases and flight becomes much more expensive for the consumer. Therefore, the increase in the speed of passenger aircraft slowed down on the approach to the speed of sound.

Fig. 1. Some four-seat aircraft produced in a series of at least 800 copies, on the same scale

The military has its own limitations, again, combining both needs (a further increase in the speed of the aircraft does little to reduce reaction time, but makes it difficult to detect targets) and physical and technical limitations (a speed of 3 or more sound speeds requires the use of non-standard materials for aviation, much more expensive and less processed than usual duralumin alloys). So rapid growth is replaced by a plateau.

But will such a picture of development persist if we choose a subclass of aviation technology that solves the same problem throughout the period under review? Will there be a period of rapid growth of characteristics or not? How quickly the change of generations differing in design solutions will be replaced by their coexistence (for this change in the phases of technology development, see ^{[1, 2]}).

This article answers these questions.

The object of the study

In articles ^{[3, 4]}, an analysis of the development of piston fighters was carried out, in ^[5] – agricultural aircraft. Passenger cars are the next big class, but their commercial load has grown dramatically over the century, so it's difficult to compare the six-seat Junkers F.13 (1919) and the wide-body Boeing 747 (1969).

Therefore, a subgroup with the same commercial load was chosen for the study, namely, four–seat, including pilot, general-purpose aircraft. This is one of the most popular classes.

Such aircraft are widely in demand, they are used both as "air taxis", and as private planes, and, often, as training or patrol, and as glider towers, and sanitary, and for many other purposes. Of course, we do not include combat and cargo aircraft with a crew of four people in this class.

The almost constant commercial load (although the estimated mass of a person in aviation has grown noticeably over the XX century) greatly reduces the spread of aircraft characteristics. Almost all four-seat aircraft have the same cabin layout: two rows of two seats. In three-seat airplanes, there are more options: one or two people in front.

The uniformity of tasks, layout, and load reduces the variation in the characteristics of four-seat aircraft and allows you to isolate the changes associated with the progress in aviation.