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Standard Hovercraft design in 1968
Like Hoover, Hovercraft has become a generic term but it started out as the product name of vehicles made by Saunders-Roe and designed by Christopher Cockerell. According to The History of the Hovercraft, the vehicle is the only form of transport not inspired by nature and so represents a feat of pure engineering, technological skill and invention.
Cockerell’s experiments began by investigating boats. He noted that wave resistance cannot be removed but could be minimised. He also observed that friction from skates and sleighs causes ice to melt which provides lubrication that allows for a very efficient sliding motion. It was this effect that he sought to replicate with air.
Following many trials, Cockerell concluded that a cushion could be sealed in place by a curtain of jets of air ejected downwards and inwards all around the periphery of the craft. The cushion pressure, on the base area of the craft, would produce a greater upward force than the effect of the jet on its own. This led to the concept of flexible extensions, cited in his 1958 patent.
The invention was placed on a secrets list in 1956. Inventors were obliged to inform the government of any invention likely to have military application. The Ministry of Supply placed an evaluation contract with Saunders-Roe so that the concept could be tested and verified.
Rapid transit: Cockerell (above left) shows off a model of his tracked hovercraft concept
But the idea was so new that state experts couldn’t do the testing. The ministry therefore dropped the product, leaving Cockerell free to form Hovercraft Ltd. Following declassification in 1958, the project was sponsored by the National Research Development Corporation (NRDC).
The NRDC was an independent public body formed in 1948 by parliament to act with industry to bring to commercial success promising ideas and inventions. When development was complete, its role was to enable firms to manufacture the products. Firms made goods under licences issued by the NRDC, and in return the companies paid the corporation royalties on sales.
The NRDC saw the hovercraft as one of many inventions that would restore post-war Britain to prosperity: technological progress would secure this through new industries and exports. The corporation was uniquely placed to seize upon the promise of hovercraft, and an order was placed with Saunders-Roe. The company's work to develop the vehicle was such a success that in 1970 the engineer Sir Eric Mensforth said that “the hovercraft has certainly greatly enhanced British prestige”.
Cockerell saw the potential to use hovercraft on land in rapid-transit systems. The craft would sit in tracks built above roads to provide cost-efficient, fast public transport that reduced congestion. Cockerell set to work developing tracked hovercraft throughout the 1960s.
The idea was to use another British invention, the linear induction motor, to produce a train system that would provide a 250-300mph inter-city service with lower capital costs than roads and other high-speed solutions.
Flying boat: Vickers-Armstrong hovercraft from the 1960s
It was proposed that a British network be linked via a Channel bridge to a continental system: Paris to London would have taken an hour! A concrete inverted-T test rig was erected to examine the properties of a multi-pad hovercraft operating at high cushion pressures.
It was thought that tracked hovercraft would reduce journey times and fatigue, with cheaper fares and better all-weather reliability than air travel. There are parallels with today's debate about high-speed rail which also highlights the economic and social costs involved in removing or circumnavigating existing structures. At least elevated systems do not destroy the continuity of land below. But the tracked hovercraft project was cancelled in 1973 as part of government budget cuts.