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NACA-TN-3228
Aerodynamic investigation of a four-blade propeller operating through an angle-of-attack range from 0 to 180 degrees
Year: 1954
Abstract: An investigation of the aerodynamic characteristics of a four-blade rigid model propeller has been conducted in the Langley full-scale tunnel for angles of attack from 0° to 180°, blade angles from 0° to 67.5°, and a range of advance ratio from 0 to 6.2. The investigation included a preliminary exploration of vertical descent and a comparison with theory of the rate of change of the normal-force coefficient with angle of attack and of the aerodynamic characteristics of the propeller at zero angle of attack.
The static-thrust results indicate that the blade angel for the maximum figure of merit is slightly greater than 8°. The blade angle for maximum efficiency for forward flight at zero angle of attack is approximately 60°. For the unstalled portion of the advance-ratio range investigated, thrust, power, and normal-force coefficients increase with increasing angle of attack for a given value of advance ratio and blade angle. Vertical-descent velocity should probably be limited to values removed somewhat from the slipstream velocity because of increasingly violent fluctuations of forces and moments as the descent velocity approaches the slipstream velocity because of increasingly violent fluctuations of forces and moments as the descent velocity approaches the slipstream velocity in a fully developed vertex-ring state of flow at the propeller disk.
The Theoretical method used for calculating the rate of change of the normal-force coefficients with angle of attack, normally applied to propellers, does not adequately predict the experimentally determined results for angles of attack greater than 15°. For the blade angles investigated, the strip-analysis theory using available two-dimensional airfoil data adequately predicted the variation of the thrust and power coefficients and efficiency with advance ratio for an angle of attack of 0°.
The static-thrust results indicate that the blade angel for the maximum figure of merit is slightly greater than 8°. The blade angle for maximum efficiency for forward flight at zero angle of attack is approximately 60°. For the unstalled portion of the advance-ratio range investigated, thrust, power, and normal-force coefficients increase with increasing angle of attack for a given value of advance ratio and blade angle. Vertical-descent velocity should probably be limited to values removed somewhat from the slipstream velocity because of increasingly violent fluctuations of forces and moments as the descent velocity approaches the slipstream velocity because of increasingly violent fluctuations of forces and moments as the descent velocity approaches the slipstream velocity in a fully developed vertex-ring state of flow at the propeller disk.
The Theoretical method used for calculating the rate of change of the normal-force coefficients with angle of attack, normally applied to propellers, does not adequately predict the experimentally determined results for angles of attack greater than 15°. For the blade angles investigated, the strip-analysis theory using available two-dimensional airfoil data adequately predicted the variation of the thrust and power coefficients and efficiency with advance ratio for an angle of attack of 0°.
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| contributor author | NASA - National Aeronautics and Space Administration (NASA) | |
| date accessioned | 2017-09-04T15:45:54Z | |
| date available | 2017-09-04T15:45:54Z | |
| date copyright | 01/01/1954 | |
| date issued | 1954 | |
| identifier other | PTNUYDAAAAAAAAAA.pdf | |
| identifier uri | https://yse.yabesh.ir/std/handle/yse/48495 | |
| description abstract | An investigation of the aerodynamic characteristics of a four-blade rigid model propeller has been conducted in the Langley full-scale tunnel for angles of attack from 0° to 180°, blade angles from 0° to 67.5°, and a range of advance ratio from 0 to 6.2. The investigation included a preliminary exploration of vertical descent and a comparison with theory of the rate of change of the normal-force coefficient with angle of attack and of the aerodynamic characteristics of the propeller at zero angle of attack. The static-thrust results indicate that the blade angel for the maximum figure of merit is slightly greater than 8°. The blade angle for maximum efficiency for forward flight at zero angle of attack is approximately 60°. For the unstalled portion of the advance-ratio range investigated, thrust, power, and normal-force coefficients increase with increasing angle of attack for a given value of advance ratio and blade angle. Vertical-descent velocity should probably be limited to values removed somewhat from the slipstream velocity because of increasingly violent fluctuations of forces and moments as the descent velocity approaches the slipstream velocity because of increasingly violent fluctuations of forces and moments as the descent velocity approaches the slipstream velocity in a fully developed vertex-ring state of flow at the propeller disk. The Theoretical method used for calculating the rate of change of the normal-force coefficients with angle of attack, normally applied to propellers, does not adequately predict the experimentally determined results for angles of attack greater than 15°. For the blade angles investigated, the strip-analysis theory using available two-dimensional airfoil data adequately predicted the variation of the thrust and power coefficients and efficiency with advance ratio for an angle of attack of 0°. | |
| language | English | |
| title | NACA-TN-3228 | num |
| title | Aerodynamic investigation of a four-blade propeller operating through an angle-of-attack range from 0 to 180 degrees | en |
| type | standard | |
| page | 63 | |
| status | Active | |
| tree | NASA - National Aeronautics and Space Administration (NASA):;1954 | |
| contenttype | fulltext |