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Theoretical study of the effect of ground proximity on the induced efficiency of helicopter rotors
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Heyson, H. H. |
| Copyright Year | 1977 |
| Description | A study of rotors in forward flight within ground effect showed that the ground-induced interference is an upwash and a decrease in forward velocity. The interference velocities are large, oppose the normal flow through the rotor, and have large effects on the induced efficiency. Hovering with small ground clearances may result in significant blade stall. As speed is increased from hover in ground effect, power initially increases rather than decreases. At very low heights above the ground, the power requirements become nonlinear with speed as a result of the streamwise interference. The streamwise interference becomes greater as the wake approaches the ground and eventually distorts the wake to form the ground vortex which contributes to certain observed directional stability problems. |
| File Size | 2933565 |
| Page Count | 96 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_19770017115 |
| Archival Resource Key | ark:/13960/t6xw96t9s |
| Language | English |
| Publisher Date | 1977-05-03 |
| Access Restriction | Open |
| Subject Keyword | Aerodynamics Aerodynamic Drag Helicopter Tail Rotors Hovering Stability Upwash Rotor Aerodynamics Helicopter Performance Ground Effect Aerodynamics Rotary Wings Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Technical Report |
