Accession Number : ADA290130

Title :   Hot Gas Ingestion Effects On Fuel Control Surge Recovery and AH-1 Rotor Drive Train Torque Spikes.

Descriptive Note : Final rept. Sep-Oct 92,

Corporate Author : COLTEC INDUSTRIES INC WEST HARTFORD CT CHANDLER EVANS CONTROL SYSTEMS DIV

Personal Author(s) : Tokarski, Frank ; Desai, Mihir ; Books, Martin ; Zagranski, Raymond

PDF Url : ADA290130

Report Date : APR 1994

Pagination or Media Count : 54

Abstract : This report summarizes the work accomplished through computer simulation to understand the impact of the hydromechanical turbine assembly (TA) fuel control on rocket gas ingestion induced engine surges on the AH-1 (Cobra) helicopter. These surges excite the lightly damped torsional modes of the Cobra rotor drive train and can cause overtorqueing of the tail rotor shaft. The simulation studies show that the hydromechanical TA control has a negligible effect on drive train resonances because its response is sufficiently attenuated at the resonant frequencies. However, a digital electronic control working through the TA control's separate, emergency fuel metering system has been identified as a solution to the overtorqueing problem. State-of-the-art software within the electronic control can provide active damping of the rotor drive train to eliminate excessive torque spikes due to any disturbances including engine surges and aggressive helicopter maneuvers. Modifications to the existing TA hydromechanical control are relatively minor, and existing engine sensors can be utilized by the electronic control. Therefore, it is concluded that the combination of full authority digital electronic control (FADEC), with hydromechanical backup using the existing TA control enhances flight safety, improves helicopter performance, reduces pilot workload and provides a substantial payback for very little investment.

Descriptors :   *COMPUTERIZED SIMULATION, *ATTACK HELICOPTERS, *GAS TURBINES, *HOT GASES, *INGESTION(ENGINES), *OVERLOAD, *TORQUE, *HYDROMECHANICS, *TAIL ROTORS, COMPUTER PROGRAMS, CONTROL, DIGITAL SYSTEMS, RECOVERY, EMERGENCIES, DETECTORS, STATE OF THE ART, PERFORMANCE(ENGINEERING), PILOTS, DAMPING, ELECTRONIC EQUIPMENT, RESONANT FREQUENCY, TURBINES, AVIATION FUELS, SHAFTS(MACHINE ELEMENTS), FLIGHT MANEUVERS, AVIATION SAFETY, SURGES, TORSION, SPIKES.

Subject Categories : Safety Engineering
      Jet and Gas Turbine Engines
      Helicopters

Distribution Statement : APPROVED FOR PUBLIC RELEASE