contra-rotary

contra-rotary adj TECH gegenläufig

contra-rotary ripper WERKZ gegenläufiger Aufreißer m

SUBJECT AREA: Aerospace

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Between 1911 and 1914 Heinrich Focke and Georg Wulf built a monoplane and some years later, in 1924, they founded the Focke-Wulf company. They designed and built a variety of civil and military aircraft including the F 19Ente, a tail-first design of 1927. This canard layout was thought to be safer than conventional designs but, unfortunately, it crashed, killing Wulf. Around 1930 Focke became interested in rotary-wing aircraft, and in 1931 he set up a company with Gerd Achgelis to conduct research in this field. The Focke-Wulf company took out a licence to build Cierva autogiros. Focke designed an improved autogiro, the Fw 186, which flew in 1938; it was entered for a military competition, but it was beaten by a fixed-wing aircraft, the Fieseler Storch. In May 1935 Focke resigned from Focke-Wulf to concentrate on helicopter development with the Focke-Achgelis company. His first design was the Fa 61 helicopter, which utilized the fuselage and engine of a conventional aeroplane but instead of wings had two out-riggers, each carrying a rotor. The engine drove these rotors in opposite directions to counteract the adverse torque effect (with a single rotor the fuselage tends to rotate in the opposite direction to the rotor). Following its first flight on 26 June 1936, the Fa 61 went on to break several world records. However, it attracted more public attention when it was flown inside the huge Deutschlandhalle in Berlin by the famous female test pilot Hanna Reitsch in February 1938. Focke continued to develop his helicopter projects for the Focke-Achgelis company and produced the Fa 223 Drache in 1940. This used twin contra-rotating rotors, like the Fa 61, but could carry six people. Its production was hampered by allied bombing of the factory. During the Second World War Focke- Achgelis also produced a rotor kite which could be towed behind a U-boat to provide a flying "crow's nest", as well as designs for an advanced convertiplane (part aeroplane, part helicopter). After the war, Focke worked in France, the Netherlands and Brazil, then in 1954 he became Professor of Aeroplane and Helicopter Design at the University of Stuttgart.

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SUBJECT AREA: Land transport, Ports and shipping, Railways and locomotives

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Stevens, a wealthy landowner with an estate at Hoboken on the Hudson River, had his attention drawn to the steamboat of John Fitch in 1786, and thenceforth devoted much of his time and fortune to developing steamboats and mechanical transport. He also had political influence and it was at his instance that Congress in 1790 passed an Act establishing the first patent laws in the USA. The following year Stevens was one of the first recipients of a US patent. This referred to multi-tubular boilers, of both watertube and firetube types, and antedated by many years the work of both Henry Booth and Marc Seguin on the latter.

A steamboat built in 1798 by John Stevens, Nicholas J.Roosevelt and Stevens's brother-in-law, Robert R.Livingston, in association was unsuccessful, nor was Stevens satisfied with a boat built in 1802 in which a simple rotary steam-en-gine was mounted on the same shaft as a screw propeller. However, although others had experimented earlier with screw propellers, when John Stevens had the Little Juliana built in 1804 he produced the first practical screw steamboat. Steam at 50 psi (3.5 kg/cm²) pressure was supplied by a watertube boiler to a single-cylinder engine which drove two contra-rotating shafts, upon each of which was mounted a screw propeller. This little boat, less than 25 ft (7.6 m) long, was taken backwards and forwards across the Hudson River by two of Stevens's sons, one of whom, R.L. Stevens, was to help his father with many subsequent experiments. The boat, however, was ahead of its time, and steamships were to be driven by paddle wheels until the late 1830s.

In 1807 John Stevens declined an invitation to join with Robert Fulton and Robert R.Living-ston in their development work, which culminated in successful operation of the PS Clermont that summer; in 1808, however, he launched his own paddle steamer, the Phoenix. But Fulton and Livingston had obtained an effective monopoly of steamer operation on the Hudson and, unable to reach agreement with them, Stevens sent Phoenix to Philadelphia to operate on the Delaware River. The intervening voyage over 150 miles (240 km) of open sea made Phoenix the first ocean-going steamer.

From about 1810 John Stevens turned his attention to the possibilities of railways. He was at first considered a visionary, but in 1815, at his instance, the New Jersey Assembly created a company to build a railway between the Delaware and Raritan Rivers. It was the first railway charter granted in the USA, although the line it authorized remained unbuilt. To demonstrate the feasibility of the steam locomotive, Stevens built an experimental locomotive in 1825, at the age of 76. With flangeless wheels, guide rollers and rack-and-pinion drive, it ran on a circular track at his Hoboken home; it was the first steam locomotive to be built in America.

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See also: Allen, Horatio; Cooper, Peter