The design and integration of electromechanical actuators within the U-2S aircraft

Abstract

Several current aircraft missions require the ability to fly at high altitudes. To achieve these altitudes, actuation systems must be designed to be extremely light for a given performance level. In the case of the U-2S aircraft, the need to implement a lightweight, current technology, electromechanical actuator was evident. This paper presents the Actuator Development and Replacement Program (ADARP) Phase I ground test results for the new electromechanical servo actuators developed for the U-2S aircraft. Phase I included actuator design, Autopilot Computer Unit (APCU) flight control software development, brassboard and flight development unit hardware design, aircraft integration, ground testing, and an actuator performance specification for the new electromechanical servo actuators. The ADARP program was initiated to improve actuator and aircraft performance for the life of the U-2S. The current electromechanical servo actuator system has a mean time between failure (MTBF) rate of less than 300 hours. The ADARP actuators are expected to increase the MTBF rate to a predicted 8,180 hours. It is an ADARP program design goal that the actuators will require no scheduled maintenance. The Phase I program objectives have been achieved. Ground test results indicate that the ADARP electromechanical actuators can be safely installed and flight tested during the Phase n portion of the ADARP program. This paper will explain the U-2S autopilot system, the operation of the existing and ADARP actuators, and the simulated and ground test results for both the existing and ADARP actuators.