- #1
Aun Muhammad
- 14
- 0
- TL;DR Summary
- Hey Physics Community, I'm reading a paper on Wind-Tunnel Tests carried out on a set of Dual-Rotating Propellers carried out by NACA in the 1940's. There is a paragraph I do not quite understand hope someone can explain it to me. It concerns single-rotation propellers. Thanks.
Hoping that someone can explain what the optimum angular displacement between the front and rear propellers actually means here in the following paragraph. It concerns the single-rotation case of the experiment:
"Both the eight-blade single- and dual-rotating propellers were mounted in four-way hubs spaced 9 15/16 inches apart, thereby providing identical blade shank and spinner conditions. Preliminary tests were made to determine the optimum angular displacement between the front and rear propeller blades for the single-rotation test; the blades of the front propeller were set to lead the blades of the rear-propeller by 75°, 52.5° and 30°. Although the results indicated little difference between these three spacings, the 52.5° spacing was considered the best. Equal spacing of 45° was not possible owing to a limitation imposed by the shaft spline."
"Both the eight-blade single- and dual-rotating propellers were mounted in four-way hubs spaced 9 15/16 inches apart, thereby providing identical blade shank and spinner conditions. Preliminary tests were made to determine the optimum angular displacement between the front and rear propeller blades for the single-rotation test; the blades of the front propeller were set to lead the blades of the rear-propeller by 75°, 52.5° and 30°. Although the results indicated little difference between these three spacings, the 52.5° spacing was considered the best. Equal spacing of 45° was not possible owing to a limitation imposed by the shaft spline."
Attachments
Last edited: