An Efficient Propeller Design
Efficient Propeller Design |
AbstractHow does a helicopter generate enough lift to fly? How does a speedboat get moving fast enough to pull someone on water skis? Here 's a project on designing propellers to do the job. ObjectiveThe goal of this project is to investigate how changes in chord length affect the efficiency of propellers.IntroductionA propeller, like an airplane wing, is an airfoil: a curved surface that can generate lift when air moves over it. When air moves over the surface of a moving propeller on an airplane, the air pressure in front of the propeller is reduced, and the air pressure behind the propeller is increased. The pressure imbalance tends to push the airplane forward. We say that the propeller is generating thrust.The same principle applies to helicopter propellers, only now the propeller rotates around the vertical axis. The pressure on top of the propeller is reduced, and the pressure underneath is increased, generating lift.The illustration below (Figure 1) defines some terms that are used to describe the shape of a propeller. The radius (r) of the propeller is the distance from the center to the tip. The chord length (c) is the straight-line width of the propeller at a given distance along the radius. Depending on the design of the propeller, the chord length may be constant along the entire radius, or it may vary along the radius of the propeller. Another variable is the twist angle (β) of the propeller, which may also vary along the radius of the propeller. | Figure 1. Illustration of terms used to describe propellers. The radius, r, of the propeller, is the distance from the center to the tip, along the center line. The chord length, c, is the straight-line width of the propeller at a given distance along the radius. The twist angle, β, is the local angle of the blade at a given distance along the radius (Hepperle, 2006). |
In this project you will investigate how changing the chord length affects the efficiency of the
AbstractHow does a helicopter generate enough lift to fly? How does a speedboat get moving fast enough to pull someone on water skis? Here 's a project on designing propellers to do the job. ObjectiveThe goal of this project is to investigate how changes in chord length affect the efficiency of propellers.IntroductionA propeller, like an airplane wing, is an airfoil: a curved surface that can generate lift when air moves over it. When air moves over the surface of a moving propeller on an airplane, the air pressure in front of the propeller is reduced, and the air pressure behind the propeller is increased. The pressure imbalance tends to push the airplane forward. We say that the propeller is generating thrust.The same principle applies to helicopter propellers, only now the propeller rotates around the vertical axis. The pressure on top of the propeller is reduced, and the pressure underneath is increased, generating lift.The illustration below (Figure 1) defines some terms that are used to describe the shape of a propeller. The radius (r) of the propeller is the distance from the center to the tip. The chord length (c) is the straight-line width of the propeller at a given distance along the radius. Depending on the design of the propeller, the chord length may be constant along the entire radius, or it may vary along the radius of the propeller. Another variable is the twist angle (β) of the propeller, which may also vary along the radius of the propeller. | Figure 1. Illustration of terms used to describe propellers. The radius, r, of the propeller, is the distance from the center to the tip, along the center line. The chord length, c, is the straight-line width of the propeller at a given distance along the radius. The twist angle, β, is the local angle of the blade at a given distance along the radius (Hepperle, 2006). |
In this project you will investigate how changing the chord length affects the efficiency of the
Bibliography: * Wikipedia is a good place to start for basic information on propellers: Wikipedia contributors, 2006