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engine to drive two propellers in opposite rotation. Contra-rotating propellers are also common in some marine transmission systems, in particular for large speed boats with planing hulls. Two propellers are arranged one behind the other, and power is transferred from the engine via
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The propeller efficiency is increased by recovering energy from the tangential (rotational) flow from the leading propeller. Tangential flow does not contribute to thrust, conversion of tangential to axial flow increases both thrust and overall system
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due to the natural torque compensation and are also used in some motor boats. The cost of boring out the outer shafts and problems of mounting the inner shaft bearings are not worth pursuing in case of normal
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While several nations experimented with contra-rotating propellers in aircraft, only the United
Kingdom and Soviet Union produced them in large numbers. The U.S. worked with several prototypes, including the
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81:, a term which describes propellers rotating in opposite directions but sitting apart from each other on separate shafts instead of sharing a common axis.
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The efficiency of a contra-rotating propeller is somewhat offset by its mechanical complexity. Nonetheless, coaxial contra-rotating propellers and
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have commonly used contra-rotating propellers to give the maximum possible speed within a limited diameter as well as counteracting the
42:, is a technique whereby parts of a mechanism rotate in opposite directions about a common axis, usually to minimise the effect of
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The mechanical installation of coaxial contra-rotating shafts is complicated and expensive and requires more maintenance.
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211:), an integrated diesel, transmission and pulling contra-rotating propellers for motor yachts.
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Contra-rotating propellers have benefits when providing thrust for boats for the same reasons.
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that would otherwise tend to cause the torpedo to rotate around its own longitudinal axis.
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The hydrodynamic gains are partially reduced by mechanical losses in shafting.
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technology was advancing rapidly and the designs were deemed unnecessary.
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Two
Propellers in Tandem Turning in Opposite Ways Give Warplane New Speed
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Parts of a mechanism rotating in opposite directions on a common axis
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strike fighter uses a lift fan with contra-rotating blades.
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More power can be transmitted for a given propeller radius.
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Contra-rotating propellers should not be confused with
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184:is inspected aboard a destroyer in April 2005
50:, resulting in the maximum power of a single
89:also use a counter-rotating arrangement.
196:for ShinNihonkai Ferries in form of the
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66:. The configuration can also be used in
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262:Contra-rotating propellers are used on
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234:is compensated (negligible for larger
145:Some helicopters use contra-rotating
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312:The CRP Azipod® Propulsion Concept
149:mounted one above the other. The
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157:turning in opposite directions.
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29:coaxial contra-rotating rotors
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153:helicopter uses non-coaxial
112:Aircraft propulsion and lift
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318:, ABB, 2002, archived from
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79:counter-rotating propellers
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209:Inboard Performance System
118:Contra-rotating propellers
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96:are moderately common in
46:. Examples include some
281:Use in marine propulsion
85:helicopters such as the
336:home : Volvo Penta
207:have launched the IPS (
40:coaxial contra-rotating
230:The propeller-induced
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182:Mark 46 Mod 5A torpedo
104:applications, such as
38:, also referred to as
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299:ABB Marine Solutions
155:intermeshing rotors
48:aircraft propellers
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172:Marine propulsion
166:F-35 Lightning II
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147:coaxial rotors
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72:coaxial rotors
61:planetary gear
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132:Lockheed XFV
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83:Tandem-rotor
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64:transmission
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245:efficiency.
205:Volvo Penta
151:H-43 Huskie
128:Convair XFY
367:Propellers
287:References
225:Advantages
140:jet engine
68:helicopter
264:torpedoes
215:Torpedoes
106:torpedoes
56:turboprop
31:, in 1989
23:A Soviet
361:Category
275:See also
98:military
134:"Pogo"
219:torque
200:Azipod
94:rotors
52:piston
44:torque
323:(PDF)
316:(PDF)
269:ships
236:ships
162:F-35B
102:naval
25:Ka-32
198:CRP
160:The
136:VTOL
130:and
190:ABB
54:or
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180:A
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