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A low disk loading is a direct indicator of high lift thrust efficiency. [4] Increasing the weight of a helicopter increases disk loading. For a given weight, a helicopter with shorter rotors will have higher disk loading, and will require more engine power to hover. A low disk loading improves autorotation performance in rotorcraft.
In geometry, a disk (also spelled disc) [1] is the region in a plane bounded by a circle. A disk is said to be closed if it contains the circle that constitutes its boundary, and open if it does not. [2] For a radius, , an open disk is usually denoted as and a closed disk is ¯.
This is a control-volume analysis; the control volume must contain all incoming and outgoing flow in order to use the conservation equations. The flow is non-compressible. Density is constant, and there is no heat transfer. Uniform pressure is applied to the disk. (No radial dependence on pressure in this 1-D model.)
The amount of deflection can be determined by solving the differential equations of an appropriate plate theory. The stresses in the plate can be calculated from these deflections. Once the stresses are known, failure theories can be used to determine whether a plate will fail under a given load.
The essence of the actuator-disc theory is that if the slip is defined as the ratio of fluid velocity increase through the disc to vehicle velocity, the Froude efficiency is equal to 1/(slip + 1). [2] Thus a lightly loaded propeller with a large swept area can have a high Froude efficiency.
In the simplest case of a spinning disk, the angular momentum is given by [4] = where is the disk's mass, is the frequency of rotation and is the disk's radius. If instead the disk rotates about its diameter (e.g. coin toss), its angular momentum L {\displaystyle L} is given by [ 4 ] L = 1 2 π M f r 2 {\displaystyle L={\frac {1}{2}}\pi Mfr^{2}}
In the case of a disk seen face-on, area density for a given area of the disk is defined as column density: that is, either as the mass of substance per unit area integrated along the vertical path that goes through the disk (line-of-sight), from the bottom to the top of the medium:
Variation of Pressure and Velocity of Flow through a Propeller disc. [1] In the figure, the thickness of the propeller disc is assumed to be negligible. The boundary between the fluid in motion and fluid at rest is shown. Therefore, the flow is assumed to be taking place in an imaginary converging duct [1] [2] where: D = Diameter of the ...