Copyright © Philip M. Parker, INSEAD. Terms of Use.
Definition: Propeller |
PropellerNoun1. A mechanical device that rotates to push against air or water. Source: WordNet 1.7.1 Copyright © 2001 by Princeton University. All rights reserved. |
Date "propeller" was first used in popular English literature: sometime before 1844. (references) |
| Domain | Definition |
Transportation | An airscrew is a screw propeller designed to operate in air. Source: European Union. (references) |
Electrical Engineering | Wind collector of a horizontal axis machine, consisting of a number of blades disposed radially round a shaft to which they are attached. Source: European Union. (references) |
Food & Agriculture | Any device which will produce thrust to propel a vehicle. The most common form is the screw propeller, which basically consists of a central hub and a number of fixed blades extending out radially from the hub. Lift is generated by the blades when the propeller is rotated. One component of the lift force produces the desired thrust and the other component creates torque which must be overcome by the engine to sustain rotation. Source: European Union. (references) |
Source: compiled by the editor from various references; see credits. | |
(From Wikipedia, the free Encyclopedia)
A propeller can be seen as a rotating fin in water or a wing in air. The horizontal axis of rotation produces a dynamic force as thrust. The force produced is from the difference in pressure from the forward and rear surfaces of the blades.
Aircraft propellers
On an aircraft, the propeller is an airfoil, much like the wing of an aircraft, except that the shape of the airfoil varies along the length of the blade, however any point on on the blade describes a helix as it moves through the air. The motion of the propeller blade, when placed at a positive angle of attack, produces forward thrust and tangential resistance. The resistance produces a turning moment about the propeller axis, called resistance torque, which it is necessary for the engine to overcome.
An propeller's efficiency is determined by (thrust x axial speed)/(resistance torque x rotational speed). Changes to a propeller's efficiency are produced by a number of factors, notably adjustments to the helix angle, the angle between the resultant relative velocity and the blade rotation direction, and to blade pitch. Very small pitch and helix angles give a good performance against resistance but provide little thrust, while larger angles have the opposite effect. The best helix angle is as if the blade was a wing producing much more lift than drag, roughly 45° in practice. However due to the shape of the propeller only part of the blade can actually be operating at peak efficiency, the outer part of the blade produces the most thrust and so the blade is positioned at a pitch that gives optimum angle to that portion. Since a large portion of the blade is therefore at a inefficient angle the inboard ends of the blade are subsumed into a streamlined spinner to reduce the resistance torque that would otherwise be created.
Very high efficiency propellers are similar in aerofoil section to a low drag wing and as such are poor in operation when at other than their optimum angle of attack. It required advanced control systems and better section profiling to counter the need for accurate matching of pitch to flight speed and engine speed to power so as to make these type of propellers usable.
However with a propeller at a pitch angle of 45° at low flight speeds the angle of attack will be high, possibly high enough to stall the aircraft. The obvious need to avoid this means that most propellers are fitted with mechanisms to allow variable pitch - Coarse pitch for high speed flight and fine pitch for climbing or accelerating at lower speeds. Early pitch control settings were pilot operated and so limited to only three or so settings, later systems were automatic. Variable pitch was replaced with the constant-speed mechanism.
Constant-speed propellers automatically adjust the blade pitch angle to alter resistance torque in response to sensed changes in speed. Initially in a rather crude fashion with the pilot altering the setting, but in more advanced aircraft the mechanism is linked into the entire engine management system for very fine control. The system is termed constant-speed because aeroengines produce maximum power at high revolutions and changing engine speed increases fuel consumption. It is, therefore, beneficial to run a engine at an optimum constant independent of flight speed, setting separate requirements for high power situations and cruising and controlling speed within these bands without changing engine speed.
A further consideration is the number and the shape of the blades used. Increasing the aspect ratio of the blades reduces drag but the amount of thrust produced depends on blade area, so using high aspect blades can lead to the need for a propeller diameter which is unusable. A further balance is that a smaller number of blades reduces interference effects between the blades, but to have sufficient blade area to transmit the available power within a set diameter means a compromise is needed. Increasing the number of blades also decreases the amount of work each blade is required to perform, limiting the local Mach number - a significant performance limit on propellers.
Contra-rotating propellers involves placing a second propeller rotating in the opposite direction immediately 'downstream' of the main propeller so as to recover energy lost in the swirling motion of the air in the propeller slipstream. Contra-rotation also increases power without increasing propeller diameter and provides a counter to the torque of high-power piston engines and the gyroscopic precession effects of the slipstream swirl. However on small aircraft the added cost, complexity, weight and noise of the system rarely make it worthwhile.
The propeller is usually attached to the crankshaft of the engine, either directly or through a gearbox. Light aircraft sometimes forego the weight, complexity and cost of gearing but on larger aircraft and with turboprop engines it is essential.
As mentioned, a propeller's performance suffers as the blade speed exceeds the speed of sound. As the relative air speed at the blade is rotation speed plus axial speed, a propeller blade will reach sonic speed sometime before the rest of the aircraft (with a theoretical blade the maximum aircraft speed is about 845 km/hr (Mach 0.7) at sea-level, in reality it is rather lower). When a blade tip becomes supersonic, drag and torque resistance increase suddenly and shock waves form creating a sharp increase in noise. Aircraft with conventional propellers therefore do not usually fly faster than Mach 0.6 although there are certain craft, usually military, which do operate at Mach 0.8 or higher although there is considerable fall off in efficiency.
Naturally there have been efforts to develop propellers for aircraft at high subsonic speeds. The 'fix' is similar to that of transonic wing design. The maximum relative velocity is kept as low as possible by careful control of pitch to allow the blades to have large helix angles; thin blade sections are used and the blades are swept back in a scimitar shape; a large number of blades are used to reduce work per blade and so circulation strength; contra-rotation is used. The propellers designed are more efficient than turbo-fans and in terms of cruising speed (Mach 0.7-0.85) suitable for airliners except that the noise is tremendous.
Aircraft Fans
A fan is a propeller with a large number of blades. A fan therefore produces a lot of thrust for a given diameter but the closeness of the blades means that each strongly affects the flow around the others. If the flow is supersonic this interference can be beneficial if the flow can be compressed through a series of shock waves rather that one. By placing the fan within a shaped duct specific flow patterns can be created depending on flight speed and engine performance. As air enters the duct its speed is reduced and pressure and temperature increased, if the aircraft is at a high subsonic speed this creates two advantges - the air enters the fan at a lower Mach speed and the higher temperature increases the local speed of sound. While there is a loss in efficiency as the fan is drawing on a smaller area of the free stream and so using less air, this is balanced by the ducted fan retaining efficiency at higher speeds where conventional propeller efficiency would be poor. A ducted fan or propeller also has certain benefits at lower speeds but the duct needs to be shaped in a different manner to one for higher speed flight. More air is taken in and the fan therefore operates at a efficiency equivalent to a larger unducted propeller, noise is also reduced by the ducting and should a blade become detacted the duct would contain the damage. However the duct adds weight, cost, complexity and (to a certain degree) drag.
See also Propeller wind generator.
Ship/Submarine propellers
Cavitation can happen if a propeller turns too fast in the water, with a resultant waste of energy and excessive noise production.
Source: adapted by the editor from Wikipedia, the free encyclopedia under a copyleft GNU Free Documentation License (GFDL) from the article "Propeller."
| The following table is compiled from various sources, across various languages. When English abbreviations or acronyms come from a non-English source, this is noted. | |||
| Entry | Source | Expression | Field |
| propjet | English | Propeller turned by jet engine | Mechanical Engineering |
Source: compiled by the editor, based on several corpora (additional references). | |||
Synonym: PropellerSynonym: propellor (n). (additional references) |
| Context | Synonyms within Context (source: adapted from Roget's Thesaurus). |
Regression | Propeller, screw, twin screws, turbine, jet engine. |
Ship | Jet plane, rocket plane, jet liner, turbojet, prop-jet, propeller plane; corporate plane, corporate jet, private plane, private aviation; airline, common carrier; fighter, bomber, fighter-bomber, escort plane, spy plane; supersonic aircraft, subsonic aircraft. |
| Source: adapted from Roget's Thesaurus. | |
| Domain | Usage | |
Movie/TV Titles | Der Lebende Propeller (1921) | |
Source: compiled by the editor from various references; see credits. | ||
| Domain | Title | ||
Books |
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Music |
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High Tech |
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Source: compiled by the editor from various references; see credits. | |||
| Thumbnail | Description & Credit | Thumbnail | Description & Credit |
 | Lieutenant Larsen heading over the side to check if propeller fouled OCEANOGRAPHER around the world cruise. Credit: Coast & Geodetic Survey Historical Image Collection. |  | Figure 39. Massey sounder, a propeller driven sounding device first developed in 1802 by Edward Massey. Many improvements were made to this device through the Nineteenth Century. The instrument in the image was created by Thomas Walke r in 1874. It consists of a propeller driven registering device which is fixed to a sounding line and weighted by ballast. Credit: Sailing for Science - the NOAA Fleet Then and Now. |
 | Figure 60. Joe Soundings sounder. This device was described in nautical magazine in 1832 by an individual with the pen name "Joe Soundings." It used a counter incremented by a propeller to measure the distance to the bottom. It is similar to the Massey sounder and Massey is sometimes cited as the inventor. There is no information concerning testing or use of this instrument. Credit: Sailing for Science - the NOAA Fleet Then and Now. |  | Overturned on the reef, on the western side of Apia Harbor, Upolu, Samoa, during salvage work after the storm. Note the gun mounted on her poop deck, and bent propeller shaft visible at her stern. Credit: NAVY. |
 | View looking aft with deck awash, while the monitor was operating at sea off Cape Cod, Massachusetts, 4 May 1898. Note water splashing up from the open propeller well, and the "flying" deck structure overhead. Credit: NAVY. |  | Confer on board RAdm. Barbey's flagship, 5 January 1944. They are examining a map of New Guinea. Note small propeller used as a paperweight. Credit: NAVY. |
 | Clare Boothe Luce, U.S. Ambassador to Italy, and Mr. H.S. Campbell, Director, European Division of American Pres. Lines, on the occasion of the Ambassador's appearance before the Propeller Club, Genoa, Italy. Credit: Library of Congress. |  | Mitchell Field. Business end of a bomber engine. The controllable pitch housing in the propeller hub assembly contains the mechanism that automatically adjusts the set of the three propellers. Credit: Library of Congress. |
 | YB-17 bombardment squadron, Langley Field, Virginia. A master sergeant of a bombardment squadron at Langley Field, Virginia checks over a propeller adjustment job his soldier-mechanics have just made on a big YB-17 bomber. Credit: Library of Congress. |  | Starting a propeller at the Naval Air Base, Corpus Christi, Texas. Credit: Library of Congress. |
Source: pictures compiled by the editor from various references; see picture credits. | |||
| Play | Caption | Play | Caption |
 | Low-flying propeller plan passing by; biplane flying by. | | A low-flying propeller plane passing by. |
| Source: compiled by the editor from various references; see credits. | |||
| Subject | Topic | Quote |
Civil Liberties | Togo | In June the Government refused entry to the MV Alnar, a ship carrying Liberian migrants; however, the Navy helped the ship repair its propeller and provided food and water for the passengers and crew. (references) |
Source: compiled by the editor from ICON Group International, Inc.; see credits. | ||
| "Propeller" is generally used as a noun (singular) -- approximately 100.00% of the time. "Propeller" is used about 146 times out of a sample of 100 million words spoken or written in English. Its rank is based on over 700,000 words used in the English language. Some parts-of-speech are not covered due to the samples used by the British National Corpus. (note: percents less than one-hundredth of one percent have been omitted) |
| Parts of Speech | Percent | Usage per 100 Million Words | Rank in English |
| Noun (singular) | 100% | 146 | 26,107 |
Source: compiled by the editor from several corpora; see credits.
Expressions using "propeller": adjustable pitch propeller ♦ airplane propeller ♦ blade of propeller ♦ cycloidal propeller ♦ direct drive propeller ♦ feather to a propeller ♦ feathered propeller ♦ fixed pitch propeller ♦ Hydraulic propeller ♦ Jet propeller ♦ leading sweep of propeller ♦ maximum propeller overspeed ♦ pitch diameter ratio of propeller ♦ pitch setting of propeller ♦ propeller apertrure ♦ propeller blade ♦ propeller boss ♦ propeller disc area ♦ propeller fin ♦ propeller governor ♦ propeller head ♦ propeller hub ♦ propeller jet aircraft ♦ propeller key ♦ propeller pitch ♦ propeller plane ♦ propeller shaft ♦ propeller torque ♦ propeller wheel ♦ pusher propeller ♦ reversible pitch propeller ♦ screw propeller ♦ ship's propeller ♦ shrouded propeller ♦ slip of a propeller ♦ steam propeller ♦ tractor propeller ♦ variable pitch propeller ♦ windmilling propeller. Additional references. | |
| Hyphenated Usage | |
Beginning with "propeller": propeller-driven, propeller-driven plane, propeller-heads, propeller-like. | |
Ending with "propeller": arrested-propeller, contra-propeller, turbo-propeller. | |
Containing "propeller": double-propeller plane, single-propeller plane, turbo-propeller plane, twin-propeller-plane. | |
| Source: compiled by the editor from various references; see credits. | |
| The following statistics estimate the number of searches per day across the major English-language search engines as identified by various trade publications. Hyperlinks lead to commercial use of the expression at Amazon.com. |
| Language | Translations for "propeller"; alternative meanings/domain in parentheses. | |
Albanian | helikë (prop, rotor, screw, screw propeller). (various references) | |
Arabic | مروحة (fan, screw, ventilator), مدسرة, المسير, المروحة (fan), الداسر, دافع (advocate, apologize, assert, buckler, champion, cushion, defend, guard, guard against, hold off, impetus, impulse, impulsive, inducement, motive, object, payer, projectile, propellant, propulsive, repulsive, score, stand for, stick up for, urge, vindicate). (various references) | |
Bulgarian | витло, пропелер, перка (brace and bit, bucket, fin, flapper, paddle, palm, prop, vane). (various references) | |
Chinese | 螺旋槳 , 推进器. (various references) | |
Czech | vrtule (screw), lodní šroub (screw propeller). (various references) | |
Danish | skrue (helix, screw). (various references) | |
Dutch | schroef (helix, screw), propeller (helix), schroefdraad (helix). (various references) | |
Esperanto | helico (helix). (various references) | |
Faeroese | skrúva (helix, screw). (various references) | |
Farsi | پروانه هواپیماوکشتی وغیره . (various references) | |
Finnish | potkuri (air-screw, helix, screw). (various references) | |
French | hélice (screw propeller). (various references) | |
German | Propeller (airscrew, prop, screw), Schraube (bolt, helix, male screw, prop, screw, twist), schiffsschraube (ship's propeller), luftschraube (airscrew). (various references) | |
Greek | έλικας (airscrew). (various references) | |
Hebrew | מ"חף (airscrew, impulse). (various references) | |
Hungarian | propeller (prop), légcsavar (airscrew, propeller slip, screw). (various references) | |
Indonesian | titiran (kind of mill), bolang-baling (weathervane), baling-baling (rotor, toy windmill, vane, weathercock), baling. (various references) | |
Italian | elica (airscrew, helix, screw), propulsore (airscrew, engine, jet, motor, thruster). (various references) | |
Japanese Kanji | プロトン磁力計 (probability, professional, professor, profile, profiler, profit, propaganda, propagandist, propagation, propane, propane gas, proper, property, propylene, proton magnetometer), 推進器 , 推進機 , 推進機 . (various references) | |
Japanese Katakana | すいし"き, プロペラ . (various references) | |
Korean | "진기. (various references) | |
Manx | seiyeyder (agitator, mixer), scrod (screw). (various references) | |
Pig Latin | opellerpray.(various references) | |
Portuguese | hélice (helix, screw, screw-propeller). (various references) | |
Romanian | propulsor (propelling), elice (airscrew, screw). (various references) | |
Russian | воздушный винт (airscrew), винт (helix, male screw, propellor, screw), пропеллер (airscrew, screw), двигательный (leading, locomotive, locomotor, motional, motive, motor). (various references) | |
Serbo-Croatian | propelerski, propeler (screw), elisni, elisa. (various references) | |
Spanish | hélice (airscrew, helices, helix, prop, screw, spiral). (various references) | |
Swedish | propeller (airscrew, prop, screw, windmill). (various references) | |
Turkish | pervane (fan, Miller, moth, prop, rotor). (various references) | |
Ukrainian | рушій, пропелер (airscrew, prop), двигун (engine, motor, power). (various references) | |
Vietnamese | máy đẩy đi, cái đẩy đi (propellant, propellent). (various references) | |
| Source: compiled by the editor from various translation references. | ||
Derivations | |
Words beginning with "propeller": propellers. (additional references) | |
| |
"Propeller" is suggested in spellcheckers for the following: Priapella, propale, propeler, propellar, properler, proppeler, Proteplex. (additional references) | |
| Source: compiled by the editor, based on several corpora (additional references). | |
| # of Phoneme Matches | Pronunciation | Word(s) rhyming with "propeller" (pronounced prupe"ler) |
| 4 | -p e" l er | speller. |
| 3 | -e" l er | dweller, bestseller, cellar, feller, Heller, interstellar, lamellar, reseller, seller, sheller, sneller, stellar, teller. |
Source: compiled by the editor (additional references); see credits. | ||
Scrabble® Enable2K-Verified Anagrams | |
| Words within the letters "e-e-l-l-o-p-p-r-r" | |
-2 letters: peopler. | |
-3 letters: eloper, lopper, people, pollee, poller, propel, proper, repoll, reroll, roller. | |
-4 letters: elope, leper, loper, poler, prole, repel, repro, roper. | |
-5 letters: leer, lope, lore, orle, peel, peep, peer, pele, pepo, perp, plop, pole, poll, pope, pore, pree, prep, prop, reel, repo, repp, role, roll, rope. | |
| Words containing the letters "e-e-l-l-o-p-p-r-r" | |
+1 letter: propellers. | |
| Source: compiled by the editor from various references; see credits. SCRABBLE® is a registered trademark. All intellectual property rights in and to the game are owned in the U.S.A and Canada by Hasbro Inc., and throughout the rest of the world by J.W. Spear & Sons Limited of Maidenhead, Berkshire, England, a subsidiary of Mattel Inc. Mattel and Spear are not affiliated with Hasbro. | |
| 1. Definition 2. Synonyms 3. Crosswords 4. Usage: Modern | 5. Usage: Commercial 6. Images: Slideshow 7. Images: Photo Album 8. Sounds | 9. Quotations: Non-fiction 10. Usage Frequency 11. Expressions 12. Expressions: Internet | 13. Translations: Modern 14. Abbreviations 15. Acronyms 16. Derivations | 17. Rhymes 18. Anagrams 19. Bibliography |
Copyright © Philip M. Parker, INSEAD. Terms of Use.
