A piloted simulator investigation of stability and control, display and crew-loading requirements for helicopter instrument approach. Part 2: Supporting data

Pilot rating comments and standard deviation measures of flight performance and control use are presented

A piloted simulator investigation of stability and control, display and crew-loading requirements for helicopter instrument approach. Part 1: Technical discussion and results

A ground-simulation experiment was conducted to investigate the influence and interaction of flight-control system, fight-director display, and crew-loading situation on helicopter flying qualities during terminal area operations in instrument conditions. The experiment was conducted on the Flight Simulator for Advanced Aircraft at Ames Research Center. Six levels of control complexity, ranging from angular rate damping to velocity augmented longitudinal and vertical axes, were implemented on a representative helicopter model. The six levels of augmentation were examined with display variations consisting of raw elevation and azimuth data only, and of raw data plus one-, two-, and three-cue flight directors. Crew-loading situations simulated for the control-display combinations were dual-pilot operation (representative auxiliary tasks of navigation, communications, and decision-making). Four pilots performed a total of 150 evaluations of combinations of these parameters for a representative microwave landing system (MLS) approach task

A ground-simulator investigation of helicopter longitudinal flying qualities for instrument approach

A ground-simulation experiment was conducted to investigate the direct and interactive influences of several longitudinal static and dynamic stability parameters on helicopter flying qualities during terminal-area operations in instrument conditions. Variations that were examined included five levels of static control-position gradients ranging from stable to unstable; two levels of dynamic stability for the long-period oscillation; two levels of the steady-state pitch speed gradient; two levels of angle-of-attack stability and pitch-rate damping; and two levels of stability and control augmentation. These variations were examined initially in calm air and thin in simulated light-to-moderate turbulence and wind shear. Five pilots performed a total of 223 evaluations of these parameters for a representative microwave landing system precision approach task conducted in a dual-pilot crew-loading situation

Results of NASA/FAA ground and flight simulation experiments concerning helicopter IFR airworthiness criteria

A sequence of ground and flight simulation experiments was conducted to investigate helicopter instrument-flight-rules airworthiness criteria. The first six of these experiments and major results are summarized. Five of the experiments were conducted on large-amplitude motion base simulators. The NASA-Army V/STOLAND UH-1H variable-stability helicopter was used in the flight experiment. Artificial stability and control augmentation, longitudinal and lateral control, and in pitch and roll attitude augmentation were investigated

Towards Predicting Street-Level Inundation: using Operational Forecast Modeling Techniques during 2011 Hurricane Irene

Storm surge-induced coastal inundation poses numerous personal, commercial, industrial, and sociopolitical challenges for society. Flooding can be caused by the combination of storm surge and river-induced inland flooding in many locations throughout the coastal plain. The cross-disciplinary nature of the hydrodynamics involved (hydraulics, oceanography, and hydrology), coupled with the complexity of the atmospheric forcing, makes a numerical model the best approach for a comprehensive study of the dynamics of coastal inundation. This study builds upon the lessons learned from forecast modeling experiences during 2011 Hurricane Irene in Tidewater Virginia, to ascertain the most effective way to approach predicting street-level inundation. During the storm event, a large-scale ocean model (SCHISM) was provided atmospheric forcing from the National Oceanic and Atmospheric Administration’s Global Forecast System, updated every 6 hours to simulate 9 separate 30-hour simulations, which were provided to emergency managers and the National Weather Service in Wakefield, VA. Forecast water level predictions were evaluated at 5 stations near the Hampton Roads region in the Lower Chesapeake Bay to yield an aggregate RMSE=19.9 cm. To accurately predict street-level inundation, water elevations at key points near the mouths of vulnerable tributaries can be used to drive a separate street-level high-resolution sub-grid model (UnTRIM) to simulate localized flooding events on the scale of 5-meter resolution. To this end, high-resolution Digital Elevation Models including building and roadway infrastructure were developed from Lidar-derived topography for the Hampton Roads Region of Virginia, and used to accurately predict flooding in low-lying areas of the Cities of Norfolk, Portsmouth, and Chesapeake along the Elizabeth and Lafayette Rivers. Additionally, grids were prepared for the City of Virginia Beach along the Lynnhaven River, and along Hampton, York, and Poquoson along the Back River. Tropical storm surge flood heights were validated via temporal comparison with water level observations from NOAA, the USGS, and NASA; aggregated to an average RMSE=0.18 cm. Spatial extent of flooding was evaluated using USGS data retrieved from high water marks and from rapid deployment overland water level gauges during Hurricane Irene to reveal favorable agreement with the model’s inundation predictions

Human genetics and genomics meetings going virtual: practical lessons learned from two international meetings in early 2020

The recent coronavirus disease 2019 (COVID-19) pandemic has caused worldwide disruption which also extends to the arena of scientific meetings around the world. Here, we explore the lessons learned from moving two human genetics and genomics meetings quickly to an online format in early 2020. The tips presented herein may be useful not only for future virtual meetings but may also enrich future physical if not hybrid meetings once they resum

Recent results from COMPTEL observations of Cygnus X‐1

The COMPTEL experiment on the Compton Gamma‐Ray Observatory (CGRO) has now observed Cyg X‐1 on four separate occasions during phase 1 and phase 2 of its orbital mission (April, 1991 to August, 1993). Here we report on the results of the latest analysis of these data, which provide a spectrum extending to energies greater than 2 MeV. A spectral analysis of these data, in the context of a classical Comptonization model, indicates an electron temperature much higher than previous hard X‐ray measurements would suggest (200 keV vs 60–80 keV). This implies either some limitations in the standard Comptonization model and/or the need to incorporate a reflected component in the hard X‐ray spectrum. Although significant variability near 1 MeV has been observed, there is no evidence for any ‘MeV excess.

Observations of the 1991 June 11 solar flare with COMPTEL

The COMPTEL instrument onboard of the Compton Gamma‐Ray Observatory (CGRO) is sensitive to γ‐rays in the energy range from 0.75 to 30 MeV and to neutrons in the energy range from 10 to 100 MeV. During the period of unexpectedly high solar activity in June 1991, several flares from active region 6659 were observed by COMPTEL. For the flare on June 11, we have analyzed the COMPTEL telescope data, finding strong 2.223 MeV line emission, that declines with a time constant of 11.8 minutes during the satellite orbit in which the flare occurs. It remains visible for at least 4 hours. We obtained preliminary values for the 2.2 MeV and 4–7 MeV fluences. Neutrons with energies above 20 MeV have been detected and their arrival time at the Earth is consistent with the γ‐ray emission during the impulsive phase

COMPTEL observations of gamma‐ray flares in October 1991

The COMPTEL experiment on GRO images 0.75–30 MeV celestial gamma‐radiation that falls within its 1 steradian field of view. During observation 12 (primary target Cen A) in October 1991 the sun had been in the fov and several solar flares associated with the active region 6891 had been observed. Time profile and energy spectra had been produced, using COMPTEL’s primary mode of operation (the telescope mode). Additionally the number of counts received in the D2‐single burst detector (the secondary mode of operation) are given. We summarize the preliminary results on all of these flares

Modeling Storm Surge and Inundation in Washington, DC, during Hurricane Isabel and the 1936 Potomac River Great Flood

Abstract: Washington, DC, the capital of the U.S., is located along the Upper Tidal Potomac River, where a reliable operational model is needed for making predictions of storm surge and river-induced flooding. We set up a finite volume model using a semi-implicit, Eulerian-Lagrangian scheme on a base grid (200 m) and a special feature of sub-grids (10 m), sourced with high-resolution LiDAR data and bathymetry surveys. The model domain starts at the fall line and extends 120 km downstream to Colonial Beach, VA. The model was used to simulate storm tides during the 2003 Hurricane Isabel. The water level measuring 3.1 m reached the upper tidal river in the vicinity of Washington during the peak of the storm, followed by second and third flood peaks two and four days later, resulting from river flooding coming downstream after heavy precipitation in the watershed. The modeled water level and timing were accurate in matching with the verified peak observations within 9 cm and 3 cm, and with R2 equal to 0.93 and 0.98 at the Wisconsin Avenue and Washington gauges, respectively. A simulation was also conducted for reconstructing the historical 1936 Potomac River Great Flood that inundated downtown. It was identified that the flood water, with a velocity exceeding 2.7 m/s in the downstream of Roosevelt Island, pinched through the bank northwest of East Potomac Park near DC. The modeled maximum inundation extents revealed a crescent-shaped flooding area, which was consistent with the historical surveyed flood map of the event