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Topic: Propeller

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  Propeller Propulsion
The engine takes air from the surroundings, mixes it with fuel, burns the fuel to release the energy in the fuel, and uses the heated gas exhaust to move a piston which is attached to a crankshaft.
The details are complex because the propeller acts like a rotating wing creating a lift force by moving through the air.
Propellers are not used on high speed aircraft.
www.grc.nasa.gov /WWW/K-12/airplane/propeller.html   (546 words)

 Propeller Solutions
Propeller Solutions, Inc. is a technology-based company specializing in custom performing propellers for pleasure yachts, sport-fishing vessels, high-speed vessels, and for those concerned with smoothness, efficiency, and performance.
Propeller Solutions is called on by Naval Architects, Builders, Owners, and Captains for assistance in the design process with problem-solving or for performance and efficiency solutions.
Our propeller designs range from a flat face constant pitch for slow to medium speeds, to a cambered, skewed design with a variable pitch distribution for high load conditions and maximum performance.
www.propellersolutions.com   (353 words)

  Wright 1903 Flyer - Propeller Propulsion   (Site not responding. Last check: )
The propeller blade is shaped like an airfoil and there is a pressure difference created across the blade because of the motion of the spinning blade.
The pressure difference causes large amounts of air to be accelerated through the plane of the propeller and the reaction of the vehicle to this motion generates a force called thrust.
Propellers are still used today on general aviation and commuter aircraft and were the primary propulsion system for all aircraft until the development of jet engines during World War II.
wright.nasa.gov /airplane/propeller.html   (369 words)

  Propeller - Wikipedia, the free encyclopedia
A propeller is a device which transmits power by converting it into thrust for propulsion of a vehicle such as an airplane, ship, or submarine though a fluid such as water or air, by rotating two or more twisted blades about a central shaft, in a manner analogous to rotating a screw through a solid.
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.
Contra-rotating propellers use 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.
en.wikipedia.org /wiki/Propeller   (2287 words)

 Propeller Info - Encyclopedia WikiWhat.com   (Site not responding. Last check: )
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.
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.
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.
www.wikiwhat.com /encyclopedia/p/pr/propeller.html   (1311 words)

 propeller. The Columbia Encyclopedia, Sixth Edition. 2001-05   (Site not responding. Last check: )
In a single-screw ship the propeller is mounted on the end of a shaft immediately in front of the rudder; the shaft is connected to a transmission or directly to an engine, which turns it and the propeller.
The thrust generated by the propeller is transmitted to the hull of the ship by a thrust bearing attached to the shaft.
Screw propellers are made of cast iron, cast steel, or manganese bronze, the last being noted for its resistance to corrosion.
www.bartleby.com /65/pr/propelle.html   (437 words)

 Hartzell Propeller: Product Support General Service and Maintenance
Damage to a propeller component, such as a stone nick, corrosion, or a ground strike, may act as a stress riser and become the initiation site for a fatique failure which can progress to an abrupt failure of the propeller.
The propeller should be inspected and overhauled in accordance with the proper procedures, and at the specified intervals.
Propeller vibration is normally felt throughout the RPM range, and increases in intensity with RPM.
www.hartzellprop.com /product_support/support_maintenance.htm   (2622 words)

 Office of Boating Safety Boating Articles
Propeller guards suffer to some extent from negative impact on handling characteristics, loss of power/speed, and in some circumstances can actually increase the likelihood of blunt trauma injuries, even though reducing the risk of actual propeller impact.
This is a replacement device for the propeller on outboard drives and consists of an axial flow pump enclosed in a ducted housing.
The propeller on the conventional outboard is removed and the pump impeller attaches directly onto the propeller shaft; the forward, neutral, and reverse functions are retained.
www.uscgboating.org /articles/boatingview.aspx?id=67   (1645 words)

 Propeller at opensource encyclopedia   (Site not responding. Last check: )
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/h (Mach 0.7) at sea-level, in reality it is rather lower).
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 detached the duct would contain the damage.
This design was common, but inventors endlessly experimented with different profiles and greater numbers of blades In the early days of steam power for ships, when both paddle wheels and screws were in use, ships were often characterized by their type of propellers, leading to terms like screw steamer or screw sloop.
www.wiki.tatet.com /Propeller.html   (1561 words)

 Encyclopedia article on Propeller [EncycloZine]   (Site not responding. Last check: )
A propeller's efficiency is determined by (thrust ×; axial speed)/(resistance torque × rotational speed).
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 airfoil.
Since this is an extremely inefficient regime in which to operate the propeller, it 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.
encyclozine.com /Propeller   (1589 words)

 propeller on Encyclopedia.com   (Site not responding. Last check: )
PROPELLER [propeller] device consisting of a hub with one or more blades that propels a craft to which it is attached by rotating its blades in a fluid such as air or water.
In a single-screw ship the propeller is mounted on the end of a shaft immediately in front of the rudder; the shaft is connected to a transmission or directly to an engine, which turns it and the propeller.
The thrust generated by the propeller is transmitted to the hull of the ship by a thrust bearing attached to the shaft.
www.encyclopedia.com /html/p1/propelle.asp   (968 words)

 Aerospaceweb.org | Ask Us - Number of Aircraft Propeller Blades
The job of the propeller is to "absorb" the power produced by the engine and transmit that power to the air flow passing through the propeller disk.
A propeller blade is composed of airfoil shapes just like a wing is. Increasing the camber of a propeller blade creates a greater thrust force just like increasing the camber of a wing creates a greater lift force.
Solidity simply refers to the area of the propeller disk that is occupied by solid componenets (the blades) versus that area open to the air flow.
www.aerospaceweb.org /question/propulsion/q0039.shtml   (751 words)

 Prop Tracker Boat Propeller Tuning Equipment for boat prop repairs inboard & outboard
This propeller rpm times the prop pitch determines the theoretical distance that the boat should have moved in one minute, which can be converted to a theoretical boat speed in miles per hour.Calculating boat speed in miles per hour given propeller pitch, engine RPM, final drive ratio, and estimated propeller slip.
The sophistication of electronic measuring designed for Navy propellers has been redesigned to process the data and present detailed but simple graphical reports which ‘point’ you in the right direction making propeller measuring, repair and modification a basic task.Propellers were once a mystery, electronic inspection was expensive, and software was not available.
Propeller Dynamics is conducting training from basic propeller repair to sophisticated propeller repair and tuning.
www.proptracker.com   (522 words)

 Stingray Powerboats - Propeller FAQ
When a propeller is identified as 13 3/4 x 21, it has a 13 3/4" (35 cm) diameter with 21" (53 cm) of pitch.
Massive cavitation by itself is rare, and it usually is caused by a propeller that is severely bent or has had its blade tips broken off resulting in a propeller that is far too small in diameter for the engine.
When we select a standard propeller, it is the one with the best combination for top speed, cruising, skiing, etc. In other words, it is a "general use" propeller.
www.stingrayboats.com /products/faq/prop_faq.html   (2745 words)

 Prop Scan for Boat Props, Boat Propeller repair, Tuning, sizing, calculation, sales, nibral, ski, blade, pitch, computer
Both propellers were fine tuned with Prop Scan and the pitch was reduced by ½" to 19".
Propeller Dynamics will provide extensive training and supply a long term commitment to assist you in becoming successful.
When propeller blades pass through water at an increasing speed, the pressure that holds the water to the sides of the blades is reduced which causes the formation of water vapor.
www.props.com.au   (909 words)

The mathematics of propellers is quite complex and quite frankly we don't know the efficiency of any particular model propeller and it could be anywhere between 40 and 75%, also the blade shape is very important to working out the true median or mean blade diameter.
As you can see from this drawing of the original PT Boat propeller the average blade diameter is not where the mean blade area occurs due to the blade shape.
The propeller was 28" diameter and 28" pitch and turned clockwise when looking from aft, it had a tapered fit and a keyway onto a 2" diameter propshaft.
www.pt-boat.com /propeller/propeller.html   (1070 words)

 Boat Seem Underpowered?
The propeller is investment cast of Silicon Bronze for durability, prevention of marine growth, and accuracy of pitch and blade geometry.
With a "normal" bronze propeller, a zinc is installed on the stainless steel shaft to serve as a sacrificial anode.
This is necessary since the bronze propeller attached to the stainless steel shaft in a saltwater environment creates a galvanic couple [a very noble metal (shaft) electrically connected to a less noble metal (prop) immersed in an electrolyte (saltwater)].
www.atomic4.com /propeller.html   (1003 words)

 New Jersey Scuba Diver - Artifacts & Shipwrecks - Propellers, Shafts, & Rudders
Compared to screw-type propellers, the design and construction of a paddlewheel is much simpler, and therefore they remained the dominant method of propulsion through the mid 1800s, with some examples remaining in use until after World War II.
Paddlewheels were also much more delicate than propellers, especially in the stormy northern oceans, where waves have actually smashed the paddlewheels off a number of vessels, leaving them to drift, or limp home by sail if they were so-equipped.
Ultimately, however, the paddlewheel lost out to the propeller entirely, and today it is only found on antique vessels and a few excursion boats.
www.njscuba.net /artifacts/obj_propeller.html   (571 words)

 Bombardier Corporation - Propeller Information
The propeller on your outboard motor is the means by which the horsepower, developed by the engine, is converted into thrust to propel your boat.
Generally caused by a solid shape (propeller blade) passing through the water, in such a position and speed, that a low pressure area is formed due to the inability to move through the water in nonresistant manner.
propellers are expensive, very strong for longer life, more efficient due to greater strength permitting stiffer blades, and a blade design that provides less slippage and flexing.
parts.evinrude.com /info/parts/propellers_files/prop8.htm   (2153 words)

 Basic Propeller Design
While it was not implemented until the 19th century, the propeller uses that principle to provide propulsion through the air, much like a threaded screw advances through a solid medium, but with some notable exceptions, primarily related to the loss of forward movement because the medium is not solid.
of a propeller is the theoretical distance the propeller would move forward in one revolution (similar to a screw) and conceptually is the same as the pitch of a screw, namely the distance between threads if the propeller were a continuous helix.
The propeller gains efficiency by using this same airfoil concept, and it is important to recognize that virtually all propellers have a "front", curved surface, and a "back" flat surface.
www.woodenpropeller.com /Basic_Propeller_Design.html   (691 words)

 Propeller Craft Ales
Made with softened water, Propeller London Porter is a blend of pale, roasted and chocolate malts, hopped with English and North American varieties.
Propeller Honey Wheat will not taste like honey because it is fermented, but will have a hint of honey flavour in the finish.
Propeller Honey Wheat is flavoured with Cascade Hops, these hops are a popular North American Hop prized for their distinctive spicy and citric aroma and flavour.
www.drinkpropeller.ca /beer/ourProducts.html   (682 words)

 Engine Tech - Propeller Positioning
The through-hub type propeller directs exiting exhaust gases through the barrel of the propeller, filling the void that would otherwise create a vacuum if the exhaust gasses were not present.
The reason why most through the hub propellers have ventilation holes at the front of the blades, is introduce exhaust gases onto the positive side of the blade area, creating some controlled slip to allow the motor to spool on up into its power band quickly.
Also, this type of propeller is designed to be positioned slightly “inside” the torpedo of the lower unit, forming an efficient pathway for the exhaust gases.
screamandfly.com /home/engine_tech/ask_jsre/propeller_positioning.htm   (394 words)

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