Accession Number:

ADA090398

Title:

On the Use of Active Higher Harmonic Blade Pitch Control for Helicopter Vibration Reduction,

Descriptive Note:

Corporate Author:

ARMY RESEARCH AND TECHNOLOGY LABS HAMPTON VA STRUCTURES LAB

Personal Author(s):

• Hammond,Charles E.
• Cline,John E.

Report Date:

1980-06-01

Pagination or Media Count:

17.0

Abstract:

Vibration levels have been a problem in helicopters since their inception. The reason for this lies in the method whereby the helicopter generates its lift, namely, the rotor system. As the rotor blades rotate they encounter a continuously changing aerodynamic environment which results in a continuously changing environment which results in a continuously changing aerodynamic loading on the blades. This changing environment is repeated on each revolution of the rotor. Hence, the rotor develops aerodynamic loads which are oscillatory in nature. These oscillatory loads are transferred directly to the helicopter airframe through the mechanical connection of the rotor to the airframe, i.e., the rotor-shafttransmission attachment. Oscillatory loads are also transmitted to the airframe by impingement of the rotor wake on the upper portion of the airframe, but the mechanically transferred loads are in most cases much more significant than the aerodynamically transferred loads. Author

Descriptors:

• *VIBRATION
• *ATTITUDE CONTROL SYSTEMS
• *HELICOPTER ROTORS
• CONTROL
• PITCH(INCLINATION)
• AERODYNAMIC LOADING
• WIND TUNNEL TESTS
• WAKE
• LIFT
• OSCILLATION
• TRANSONIC WIND TUNNELS
• AERODYNAMIC CONTROL SURFACES
• HARMONIC ANALYSIS
• IMPINGEMENT

Subject Categories:

• Helicopters

Distribution Statement:

APPROVED FOR PUBLIC RELEASE