12 interesting hovercraft facts about hovercraft
1/. The “hovercraft” was invented by Sir Christopher Cockerell who probably drank coffee and owned a cat – his design resulted from experiments conducted with a hair dryer, studying airflow when high-pressure air was blown between two concentric tin cans, one coffee can and the one cat food can.
2/. This produced a ring of airflow, as expected, but he noticed an unexpected benefit as well; the sheet of fast moving air presented a sort of physical barrier to the air on either side of it. This effect, which he called the “momentum curtain”. He concluded that in terms of power, a hovercraft would only need between one quarter to half of the power required by a helicopter.
3/. It took great effort for Cockerell to get his invention taken seriously. He noted that “The Navy said it was a plane not a boat; the Air Force said it was a boat not a plane; and the Army was ‘plain not interested.
4/. The SRN1 made its first hover on 11 June 1959, and made its famed successful crossing of the English Channel on 25 July 1959 piloted by Peter (“Sheepy”) Lamb, an ex-naval test pilot and the Chief Test Pilot at Saunders Roe. Christopher Cockerell was on board, and the flight took place on the 50th anniversary of Louis Blériot’s first aerial crossing. Cockerell apparently was used as ballast to improve trim on the channel crossing, an uncomfortable experience by all accounts.
5/. In December 1959, the Duke of Edinburgh visited Saunders-Roe at East Cowes and persuaded the chief test-pilot, Commander Peter Lamb, to allow him to take over the SR.N1’s controls. He flew SR.N1 so fast that he was asked to slow down a little. On examination of the craft afterwards, it was found that she had been dished in the bow due to excessive speed, damage which was never allowed to be repaired, and was from then on affectionately referred to as the ‘Royal Dent’
6/. Although the SR.N1 was successful as a testbed, the design hovered too close to the surface, even small waves would hit the bow. The solution was offered by Cecil Latimer-Needham, following a suggestion made by his business partner Arthur Ord-Hume. In 1958 he suggested the use of two rings of rubber to produce a double-walled extension of the vents in the lower fuselage. French pioneer Jean Bertin was an advocate of the “multi-skirt” approach, which used a number of smaller cylindrical skirts instead of one large skirt.
7/. In Finland, small hovercraft are widely used in maritime rescue and during the rasputitsa (“mud season”)
8/. The Marylebone Cricket Club owns a ‘hover cover’ that it uses regularly to cover the pitch at Lord’s Cricket Ground. This device is easy and quick to move, and has no pressure points, making damage to the pitch less likely.
9/. The Flymo is an air-cushion lawn mower which uses a fan on the cutter blade to provide lift. This allows it to be moved in any direction, and provides double-duty as a mulcher.
10/. Lee-on-the-Solent, Hampshire, England, is the home to the Hovercraft Museum which houses the world’s largest collection of hovercraft designs, including some of the earliest and largest.
11/. The highest recorded speed by a hovercraft is 137.4 km/h (85.38 mph), by Bob Windt (USA) at the 1995 World Hovercraft Championships on the Rio Douro River, Peso de Regua, Portugal.
12/. Hovercraft are used as ice breakers using resonance. If static force is applied to a sheet of ice it will flex slightly before suffering a catastrophic failure. Since the ice will bend slightly when any vehicle capable of travelling on ice covered water, it follows that travelling at some critical speed may to impose sufficient flexing of the ice sheet to cause resonance, and this may result in positive feedback effectively amplifying the oscillation within the body of water supporting the ice beneath the vehicle. Using a hovercraft for destruction of ice is desirable because this type of vehicle makes possible a combination of transport and ice-breaking, and its all-terrain qualities facilitate year-round operation.