The Theory and Practice of Controllable Pitch Propellers
Year: 1981 Language: english Author: COMMANDER E. R. MAY, R.N., C.Eng., F.I.Mar.E. Genre: Reference book Publisher: IMarEST ISBN: 0 900976 62 4 Format: PDF Quality: Scanned pages Pages count: 30 Description: Controllable pitch propellers were first introduced in sailing craft with auxiliary steam propulsion. The earliest auxiliary steamships frequently had lifting propellers. Much ingenuity was bestowed on unshipping and shipping propellers at sea, as an evolution. The phrase "up funnel, down screw" is typical of those days. It was soon found that the difficulties of shipping and unshipping a propeller at sea could be formidable. The objective was reconsidered. The only purpose of having a removable propeller was to reduce the induced drag when the ship was sailing. After some experience of lifting propellers, it was felt that an adequate reduction in drag might be achieved if the propeller blades could be feathered when sailing. To feather, the propeller blades were turned into a position in which their drag would be a minimum. The propellers concerned were nearly all two-bladed. They were fitted with mechanisms-usually a system of rods and levers-the ultimate function of which was to turn the blades on the pintIes to which they were secured on the cast iron boss of the propeller. Those parts of the mechanism which were outboard were permanently immersed in water. The mechanism was of the simplest description and commonly lacked any provision for lubrication.
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The Theory and Practice of Controllable Pitch Propellers
Year: 1981
Language: english
Author: COMMANDER E. R. MAY, R.N., C.Eng., F.I.Mar.E.
Genre: Reference book
Publisher: IMarEST
ISBN: 0 900976 62 4
Format: PDF
Quality: Scanned pages
Pages count: 30
Description: Controllable pitch propellers were first introduced in sailing craft with
auxiliary steam propulsion. The earliest auxiliary steamships frequently had
lifting propellers. Much ingenuity was bestowed on unshipping and shipping
propellers at sea, as an evolution. The phrase "up funnel, down screw" is
typical of those days. It was soon found that the difficulties of shipping and
unshipping a propeller at sea could be formidable. The objective was
reconsidered. The only purpose of having a removable propeller was to
reduce the induced drag when the ship was sailing. After some experience of
lifting propellers, it was felt that an adequate reduction in drag might be
achieved if the propeller blades could be feathered when sailing. To feather,
the propeller blades were turned into a position in which their drag would be
a minimum. The propellers concerned were nearly all two-bladed. They
were fitted with mechanisms-usually a system of rods and levers-the
ultimate function of which was to turn the blades on the pintIes to which they
were secured on the cast iron boss of the propeller. Those parts of the
mechanism which were outboard were permanently immersed in water. The
mechanism was of the simplest description and commonly lacked any
provision for lubrication.
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