An experimental investigation was conducted to determine the feasibility of a high-pressure (4000 psig) hydraulic fluidic vortex rate sensor. The impetus for this investigation stems from the expanding implementation of fluidics in aircraft, ground vehicle, and helicoper controls. The feasibility of a fluidic stabilization system for low-pressure pneumatic/hydraulic operation has been demonstrated(1)*. In such a system, the vehicle's angular rate is sensed by a low-pressure fluidic vortex rate sensor. Greater overall system simplicity can be achieved by direct utilization of the high-pressure hydraulic fluid from the helicopter's primary hydromechanical system. The objective of this program was to investigate the vortex rate sensor for operation with high-pressure hydraulic fluid.To accomplish this objective, a variable-geometry rate sensor was designed, fabricated, and tested. Blocked-output signal pressures were obtained over a range of temperatures and supply pressures from 0-160 F and 100-4000 psig, respectively, for supply flow rates of 0.5-3 gpm of MIL-H-5606 oil and an input angular rate range of ± 50 deg/sec. Data are presented for these operating conditions using different internal geometries. A combination of a vortex chamber diameter and vortex chamber height was found for which the output signal pressure was a maximum. Output signal pressure-flow characteristics were obtained at 4000 psig fluid pressure and 0.5 gpm supply flow rate.From this investigation, it was concluded that vortex rate sensor operation is feasible at very high (4000 psig) hydraulic fluid pressures over a wide range of temperatures.