Tentative civil airworthiness flight criteria for powered-lift transports

Representatives of the U.S., British, French, and Canadian airworthiness authorities participated in a NASA/FAA program to formulate tentative civil airworthiness flight criteria for powered-lift transports. The ultimate limits of the flight envelope are defined by boundaries in the airspeed/path-angle plane. Angle of attack and airspeed margins applied to these ultimate limits provide protection against both atmospheric disturbances and disturbances resulting from pilot actions or system variability, but do not ensure maneuvering capability directly, as the 30% speed margin does for conventional transports. Separate criteria provide for direct demonstration of adequate capability for approach path control, flare and landing, and for go-around. Demonstration maneuvers are proposed, and appropriate abuses and failures are suggested. Taken together, these criteria should permit selection of appropriate operating points within the flight envelopes for the approach, landing, and go-around flight phases which are likely to be most critical for powered-lift aircraft

Hubble Space Telescope Observations of the Black Hole X-ray Transient GRO J0422+32 Near Quiescence

We present HST/FOS ultraviolet and optical spectroscopy of the black hole X-ray transient GRO J0422+32 shortly before the system reached quiescence. We find that the accretion spectrum from 2500-9000A can be very well fit by a self-absorbed synchrotron model, with superposed HI and MgII emission lines. The explanations we suggest for this spectrum are that it is either due to active coronal regions above a geometrically thin accretion disc, or that the disc is evaporated into an advective flow.Comment: 7 pages with 7 postscript figures included, uses mn.sty. Accepted for publication in MNRA

Factors affecting handling qualities of a lift-fan aircraft during steep terminal area approaches

The XV-5B lift-fan aircraft was used to explore the factors affecting handling qualities in the terminal area. A 10 deg ILS approach task was selected to explore these problems. Interception of the glide slope at 457.2 m, glide slope tracking, deceleration along the glide slope to a spot hover were considered. Variations in airplane deck angle, deceleration schedule, and powered-lift management were studied. The overall descent performance envelope was identified on the basis of fan stall, maximum comfortable descent rate, and controllability restrictions. The collective-lift stick provided precise glide slope tracking capability. The pilot preferred a deck-parallel attitude for which he used powered lift to control glide slope and pitch attitude to keep the angle of attack near zero. Workload was reduced when the deceleration schedule was delayed until the aircraft was well established on the glide slope, since thrust vector changes induced flight path disturbances