Large-scale advanced prop-fan (LAP) blade design

Original publisher: [Windsor Locks, Conn.?]: Hamilton Standard Division, United Technologies ; [Cleveland, Ohio]: National Aeronautics and Space Administration, Lewis Research Center, [1984?] OCLC Number: (OCoLC)188768942 Subject: Airplanes -- Turbofan engines. Excerpt: ... 3.0 Requirements and Goals The design objectives for the SR-7L blade are divided into requirements and goals. The requirements are objectives which must be satisfied in the design process. The goals are additional objectives that are desired but need not be satisfied. Four conditions were used to assure the structural adequacy of the design with respect to the requirements. After this was achieved, eight addltlonal conditions were evaluated. Satisfying the requirements for these eight additional conditions was not mandatory. 3.1 Design Requirements The deslgn requirements can be divided into six categories. These categor-ies, along with the requirements of each, follow: 3.1.1 Configuration No. of blades per rotor..................... 8 Tip diameter....................:........... 2.75 m. ( 9 ft. ) Tip speed................................... 244 mps ( 800 fps ) Activity factor............................. 227.3 Direction of rotation, aft looking forward., counter-clockwise 3.1.2 Flutter Limits The Prop-Fan assembly shall be Free of flutter instabllitles over a normal Flight proflle shown in Figure 3-I For a representative aircraft installation For normal operating conditions. 3.1.3 Critical Speed Margins For the two-per-revolution ( 2-P ) excitation at 244 meters per second ( 800 feet per second ), tip rotational speed, the critical speed margin shall be a minimum of ten percent of propeller speed and resonant Frequency. As indi-cated in Figure 3-2, this margin shall be reduced inversely as the exciting order is increased from 3-P to 5-P. No I-P critical speeds sha ] 1 be permit-ted in the operating speed range and the minimum I-P margin shall be 40 per-cent of the maximum Prop-Fan operatin...