Accession Number : ADA014890


Title :   Ch-47C Fixed-System Stall-Flutter Damping


Descriptive Note : Final rept. Feb 1974-Mar 1975


Corporate Author : BOEING VERTOL CO PHILADELPHIA PA


Personal Author(s) : Baskin, Joseph M


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a014890.pdf


Report Date : Aug 1975


Pagination or Media Count : 36


Abstract : This program was conducted to evaluate the effect of fixed-system damping on stall-induced control loads. Damping was introduced into the CH-47C aft-rotor control system by connecting the housing portion of the linear damper to the longitudinal-trim system and grounding the piston portion of the damper to the aft transmission. Five damper-rate configurations were evaluated on a helicopter with a gross weight of 40,000 pounds. Data obtained in speed sweeps at five density altitudes to 10,000 feet indicate that the rotating-system loads were reduced by 16 percent and the fixed-system loads were reduced by 22 percent. The program proved that fixed-system damping is effective in reducing stall-induced control loads. Recommendations are presented for reducing these loads by softening the swashplate support as well as by increasing the effectiveness of the fixed-system damper.


Descriptors :   *FLIGHT CONTROL SYSTEMS , *HELICOPTER ROTORS , *ROTOR BLADES(ROTARY WINGS) , *HELICOPTERS , VIBRATION , AERODYNAMIC LOADING , ACTUATORS , TORQUE , PIVOTS , FLUTTER , LINKAGES , WEIGHT , STALLING , LOADS(FORCES) , DAMPING , PITCH(MOTION)


Subject Categories : Helicopters
      Fluid Mechanics


Distribution Statement : APPROVED FOR PUBLIC RELEASE