The utility of helicopter aviation is limited by the high vibration levels caused by the interaction of each rotor blade with the wake of preceding blades. Existing full-blade actuation using a swashplate has various problems such as insufficient bandwidth, limitations in the number of harmonics controlled, high maintenance, and lack of spanwise lift variation. These problems are avoided by the proposed flap operated, individual blade control system, which uses magnetostrictive actuation technology. Terfenol-D actuation has many advantages over competing technologies such as hydraulic systems, electric motors, and piezoelectric elements. These benefits include all-electric operation, simplicity and reliability, low mass, low voltage, and insensitivity to centripetal acceleration. A blade mounted Terfenol-D actuator was developed for the high-weight-penalty helicopter application. The optimum coil to Terfenol-D volume ratio was derived that gives the highest mechanical power output for a small actuator envelope and mass. A fixed ability to dissipate coil resistive losses is assumed. The magnetostrictive actuation system will weigh less than 1% of gross vehicle weight, and use only 0.7% of cruise power. Other required subsystems of the vibration reduction system are available from commercial sources or are described in the literature. Helicopter vibration reduction greater than 90% is predicted because of superior actuator performance and individual blade control. This magnetostrictive actuator technology will also produce future helicopter systems having lower noise and higher performance. Such advances will significantly improve the utility and competitiveness of helicopters for civilian and military transportation.

No abstract

Ah.~tmcf -Ttic poteiitinl of tiigli-teinpernti~rc supercondricting (].ITS) inagncts for iisc in naval mine coiiutcrmcasurc (MCM) systcms is bcing itivcstignted. Pnrnmetric studics wcrc performed to determiile an optimal system thRk fits within n 56O-ma diametcr by 3-m loiig cnvelnpc, wid is capnble o f gcnersting n dipole tnomcnt of 300 k h i ? A demonstration niodcl magnct, of dipole inoincnt 15 kAin2, was lnycr-wouiirl 011 a 457-in111 inandrcl. 'Chis is one of the lurgest layer-wound IITS solenoid inagnets constructed to datc. 'I'tie magnet is conduction-caolcd with a two-stagc cryocoolcr. It has low AC loss anit can bc rampod lip to fiill currcat (3381 A) in 1 scconcl.Tho inognot lins bcen tested to 400 A DC cirrrent with iuinimal voltegc. Thc design niid construction o f thc iiiagnet will bc prcscntcd.

No abstract

No abstract