DYNAMIC MINIMUM CONTROL AIRSPEED TESTING OF THE U.S. NAVY MODEL E-2C PLUS AIRCRAFT EQUIPPED WITH THE HAMILTON SUNDSTRAND NP2000 PROPELLER SYSTEM USING A SPLIT-THROTTLE TEST TECHNIQUE

摘要

As part of the development of the Hamilton Sundstrand (HS) NP2000 Propeller System on the U.S. Navy Model E-2C Plus Hawkeye aircraft a series of single-engine minimum control airspeed (V_(MCa)) tests were conducted. While the static V_(MCa) tests were fairly straight forward, the dynamic V_(MCa) tests required a bit more thought, research, and planning. When planning the dynamic V_(MCa) tests, the E-2C Plus NP2000 Test Team conducted research to understand the test techniques used in previous efforts, the results that were obtained, and the effect of those results on various operational facets of the aircraft. Perhaps the primary obstacle all previous test teams had faced was the high power to weight ratio of the aircraft, which resulted in nose high attitudes and rapid changes in airspeed during the maneuver. Based upon that research and team discussions, a split-throttle test technique was developed that we called the Intermediate Power Setting Technique. The Intermediate Power Setting Technique was designed to take the best aspects of the previous test techniques (stabilize at the target airspeed, maximize power asymmetry) while reducing the undesirable aspects of previous tests. Among those undesirable aspects of earlier E-2C flight tests were unrepeatable pilot input and technique resulting in large data scatter, and the non-representative of the "real world", nose high, test technique. The Intermediate Power Setting Technique was, therefore, chosen for dynamic V_(MCa) tests of the E-2C Plus NP2000 aircraft. The E-2C Plus Hawkeye aircraft tested was a twin-engine land and carrier-based aircraft that conducts the Airborne Early Warning (AEW), and the Command, Control, and Communication (C~(3)) missions. The E-2C Plus Hawkeye aircraft was manufactured by Northrop Grumman Corporation. The aircraft's maximum catapult takeoff gross weight was 55,000 lb, and the maximum arrested landing gross weight was 46,500 lb. The test aircraft was powered by two Rolls-Royce (Allison) T56-A-427 turboprop engines with a maximum horsepower rating of 5,100 Indicated Shaft Horsepower (ISHP). Each T56-A-427 engine drives a HS NP2000 propeller, which is designed to produce approximately 9,000 pounds of thrust per engine and propeller at sea level standard day conditions. This results in a thrust to weight ratio of approximately 0.33 for takeoff and 0.39 for waveoff. The purpose of this paper is multi-faceted, and not meant to simply pass on data. It is also meant to demonstrate one approach to dynamic V_(MCa) testing for a dual engine, propeller driven aircraft with a relatively high power-to-weight ratio and will also describe some of the challenges that a test team can expect. Among the many lessons learned, the importance of research to understand test techniques, results and implications, was probably the most valuable.