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Monthly Discussion

Supersonic Air Travel

The French-British supersonic Concord will be permanently grounded this year after 27 years of operation. For some this may seem as proof of failure. For others, the Concord will always be a success. The question that arises concerns the future of supersonic air travel in general. When (if at all) should we expect supersonic commercial travel to come into being again?

The success of the European Concorde was compromised from its inception by the fact that the time it gained flying, it lost refueling. Supersonic propulsion requires much fuel and small payloads. The gasoline content in hydrogen (the principal energy agent) is not high enough to permit long-distance supersonic travel. In retrospect, the scrapping of the supersonic transport project (SST) back in 1971 by the Senate may have been symptomatic of fundamental, if unconscious, reasoning. The technologies at hand were simply not suitable for commercial (i.e. voluminous) supersonic travel.

The only example of massive supersonic travel today is found in rocket technology and space vehicles. They invariably use pure hydrogen as fuel, in liquid form. Furthermore, hydrogen is aviation’s typical fuel. There is a discussion of transport infrastructures in Predictions in which primary energy sources are coupled to means of transportation. Gasoline is the typical fuel for cars even though some cars are electric and we may see cars run on natural gas soon. Similarly, the typical fuel for trains was coal even if today’s trains run mostly on electricity produced from oil, and early trains ran on wood. Airplanes have been so far fueled by gasoline the same way trains were fueled by wood in the 19^th century. The typical fuel for airplanes, however, is most likely going to be a liquid form of natural gas, much richer in hydrogen than gasoline.

The Concord proved one thing, however, that supersonic travel is here to stay. The plane enjoyed much publicity and popularity. It made a cultural dent and demonstrated public’s appreciation and need for high-speed travel. The fact that it had to close operations, if somewhat prematurely, was predictable. But instead of a failure Concord constitutes a “precursor”. In last week’s newsletter there was a drawing depicting first-order deviations from a natural-growth pattern. That drawing is reproduced in Exhibit 3 below with dates on it representing milestones in commercial supersonic air travel.

Exhibit 3. The natural growth pattern often shows deviations from the S-shaped pattern such as precursors, overshoots and catching-up effects, see Predictions. Dates at 27-year intervals begin with Concord’s launch in 1976.

Following the Concord (“precursor” in the drawing) there may be a period of another 27 years or so with no commercial supersonic planes. However, once the new-fuel technology becomes established, growth in supersonic travel will be rapid because of pent-up demand. If airplane-manufacturing companies did their jobs right they should soon begin the designing of the next generation aircraft. Considering the long development time, this is the only way to timely answer the demand.