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Propeller

technology Maturity 7-9 Next article →

A propeller is a mechanical device used to generate movement through a working fluid. This fluid can be water or air.

Ship-propeller 2000
Ship-propeller 2000

The device consists of a central hub with radiating blades. These blades are set at a specific pitch, or angle. This arrangement forms a helical spiral shape. When the propeller rotates, it exerts linear thrust upon the fluid. This thrust is the force that drives a boat through water or an aircraft through the air.

Pratt & Whitney Canada PW100 Dash 8 OE-LGD 01
Pratt & Whitney Canada PW100 Dash 8 OE-LGD 01

The mechanism relies on a physical law called Bernoulli's principle. As the propeller blades rotate, they move through the fluid. This movement creates a pressure difference between the two surfaces of the blade. This difference in pressure exerts a force on the fluid. Because the fluid is pushed, the propeller receives a force in the opposite direction. This process converts rotational motion into forward travel.

Cavitating-prop
Cavitating-prop

Propellers can vary in design and application. Marine propellers are often called screws. They usually consist of helical blades rotating on a shaft with a horizontal axis. In aviation, they are often called airscrews. While a propeller can have a single blade, most designs use multiple blades. This is done to balance the forces involved during rotation.

Controllable pitch propeller schematic
Controllable pitch propeller schematic

The history of the propeller traces back to ancient methods of moving water. The principle is derived from stern sculling, where a blade moves through an arc. The innovation of the screw propeller was extending that arc through more than 360 degrees.

Archimedes screw
Archimedes screw

Early records from Ancient Mesopotamia describe bronze water screws used by King Sennacherib. Later, Archimedes used a screw to lift water for irrigation. This device became known as Archimedes' screw. Modern designs likely began by truncating a long screw at the tip.

Many inventors contributed to the development of practical propellers. In 1775, David Bushnell designed the Turtle, a submarine. It used a brass propeller that could be turned by hand or foot.

F. P. Smith's original 1836 screw propeller patent
F. P. Smith's original 1836 screw propeller patent

In 1827, Josef Ressel invented a screw propeller on a conical base. He tested it on a ship called the Civetta in 1829. The ship reached a speed of 6 knots. In 1835, Francis Pettit Smith and John Ericsson began working on propeller problems separately. Smith's wooden propeller accidentally became more efficient when it broke from two turns to one. This discovery helped him improve his design.

Francis Pettit Smith's work was vital for maritime history. He built a six-ton canal boat called the Francis Smith to demonstrate his invention.

Illustrirte Zeitung (1843) 21 335 1 Archimedische Schraube des Dampfschiffes Archimedes
Illustrirte Zeitung (1843) 21 335 1 Archimedische Schraube des Dampfschiffes Archimedes

In 1839, he launched the Archimedes, the world's first steamship driven by a screw propeller. This ship proved that propellers were more efficient than paddlewheels. Paddlewheels are often affected by a ship's motion or changes in draft. The screw propeller provides a more steady method of propulsion. This success encouraged the Royal Navy to adopt the technology.

John Ericsson also made significant contributions to the field. He built the Francis B. Ogden, which reached 10 miles per hour on the River Thames. Although the British Admiralty was initially skeptical, Ericsson's work led to the design of the first U.S. Navy screw-propelled warship. The development of these different designs allowed for specialized use in both military and commercial sectors. Today, the screw propeller remains the standard for moving many vessels through the world's oceans.

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🖼️ Images & Media (16)
File:Ship-propeller 2000.jpg
Ship-propeller 2000.jpg
File:Pratt & Whitney Canada PW100 Dash 8 OE-LGD 01.JPG
Pratt & Whitney Canada PW100 Dash 8 OE-LGD 01.JPG
File:Archimedes screw.JPG
Archimedes screw.JPG
File:F. P. Smith's original 1836 screw propeller patent.jpg
F. P. Smith's original 1836 screw...
File:EricssonCounterRotatingScrews.png
EricssonCounterRotatingScrews.png
File:Illustrirte Zeitung (1843) 21 335 1 Archimedische Schraube des Dampfschiffes Archimedes.PNG
Illustrirte Zeitung (1843) 21 335 1...
File:Great Britain propeller and rudder wideshot.jpg
Great Britain propeller and rudder wideshot.jpg
File:Precision air ATR72 5423a.gif
Precision air ATR72 5423a.gif
File:RMS Olympic's propellers.jpg
RMS Olympic's propellers.jpg
File:Cavitating-prop.jpg
Cavitating-prop.jpg
File:Cavitation Propeller Damage.JPG
Cavitation Propeller Damage.JPG
File:Propeller & anti-cavitation plate & Schilling rudder.jpg
Propeller & anti-cavitation plate &...

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