Flight-path and airspeed control during landing approach for powered-lift aircraft

Manual control of flight path and airspeed during landing approach has been investigated for powered-lift transport aircraft. An analysis was conducted to identify the behavior of the aircraft which would be potentially significant to the pilot controlling flight path and airspeed during the approach. The response characteristics found to describe the aircraft behavior were (1) the initial flight-path response and flight-path overshoot for a step change in thrust, (2) the steady-state coupling of flight path and airspeed for a step change in thrust, and (3) the sensitivity of airspeed to changes in pitch attitude. The significance of these response characteristics was evaluated by pilots on a large-motion, ground-based simulator at Ames Research Center. Coupling between flight path and airspeed was considered by the pilot to be the dominant influence on handling qualities for the approach task. Results are compared with data obtained from flight tests of three existing powered-lift V/STOL aircraft

Digital interface for bi-directional communication between a computer and a peripheral device

For transmission of data from the computer to the peripheral, the computer initially clears a flipflop which provides a select signal to a multiplexer. A data available signal or data strobe signal is produced while tht data is being provided to the interface. Setting of the flipflop causes a gate to provide to the peripherial a signal indicating that the interface has data available for transmission. The peripheral provides an acknowledge or strobe signal to transfer the data to the peripheral. For transmission of data from the peripheral to the computer, the computer presents the initially cleared flipflop. A data request signal from the peripheral indicates that the peripheral has data available for transmission to the computer. An acknowledge signal indicates that the interface is ready to receive data from the peripheral and to strobe that data into the interface

Flight evaluation of configuration management system concepts during transition to the landing approach for a powered-lift STOL aircraft

Flight experiments were conducted to evaluate two control concepts for configuration management during the transition to landing approach for a powered-lift STOL aircraft. NASA Ames' augmentor wing research aircraft was used in the program. Transitions from nominal level-flight configurations at terminal area pattern speeds were conducted along straight and curved descending flightpaths. Stabilization and command augmentation for attitude and airspeed control were used in conjunction with a three-cue flight director that presented commands for pitch, roll, and throttle controls. A prototype microwave system provided landing guidance. Results of these flight experiments indicate that these configuration management concepts permit the successful performance of transitions and approaches along curved paths by powered-lift STOL aircraft. Flight director guidance was essential to accomplish the task

Birkhoff for Lovelock Redux

We show succinctly that all metric theories with second order field equations obey Birkhoff's theorem: their spherically symmetric solutions are static.Comment: Submitted to CQ

Extraordinary sensitivity of the electronic structure and properties of single-walled carbon nanotubes to molecular charge-transfer

Interaction of single-walled carbon nanotubes with electron donor and acceptor molecules causes significant changes in the electronic and Raman spectra, the relative proportion of the metallic species increasing on electron donation through molecular charge transfer, as also verified by electrical resistivity measurements.Comment: 15 pages, 5 figurre

Photographic Assessment of Change in Trichotillomania: Psychometric Properties and Variables Influencing Interpretation

Although photographic assessment has been found to be reliable in assessing hair loss in Trichotillomania, the validity of this method is unclear, particularly for gauging progress in treatment. The current study evaluated the psychometric properties of photographic assessment of change in Trichotillomania. Photographs showing hair loss of adults with Trichotillomania were taken before and after participating in a clinical trial for the condition. Undergraduate college students (N = 211) rated treatment response according to the photos, and additional archival data on hair pulling severity and psychosocial health were retrieved from the clinical trial. Photographic assessment of change was found to possess fair reliability (ICC = 0.53), acceptable criterion validity (r = 0.51), good concurrent validity (r = 0.30–0.36), and excellent incremental validity (ΔR2 = 8.67, p \u3c 0.01). In addition, photographic measures were significantly correlated with change in quality of life (r = 0.42), and thus could be considered an index of the social validity of Trichotillomania treatment. Gender of the photo rater and pulling topography affected the criterion validity of photographic assessment (partial η2 = 0.05–0.11). Recommendations for improving photographic assessment and future directions for hair pulling research are discussed

Flight evaluation of the STOL flare and landing during night operations

Simulated instrument approaches were made to Category 1 minimums followed by a visual landing on a 100 x 1700 ft STOL runway. Data were obtained for variations in the aircraft's flare response characteristics and control techniques and for different combinations of aircraft and runway lighting and a visual approach slope indication. With the complete aircraft and runway lighting and visual guidance no degradation in flying qualities or landing performance was observed compared to daylight operations. elimination of the touchdown zone floodlights or the aircraft landing lights led to somewhat greater pilot workload; however, the landing could still be accomplished successfully. Loss of both touchdown zone and aircraft landing lights led to a high workload situation and only a marginally adequate to inadequate landing capability

Radio-frequency discharges in Oxygen. Part 1: Modeling

In this series of three papers we present results from a combined experimental and theoretical effort to quantitatively describe capacitively coupled radio-frequency discharges in oxygen. The particle-in-cell Monte-Carlo model on which the theoretical description is based will be described in the present paper. It treats space charge fields and transport processes on an equal footing with the most important plasma-chemical reactions. For given external voltage and pressure, the model determines the electric potential within the discharge and the distribution functions for electrons, negatively charged atomic oxygen, and positively charged molecular oxygen. Previously used scattering and reaction cross section data are critically assessed and in some cases modified. To validate our model, we compare the densities in the bulk of the discharge with experimental data and find good agreement, indicating that essential aspects of an oxygen discharge are captured.Comment: 11 pages, 10 figure

Thinning and Harvesting Regimesf or Yellow-Poplar

Grade I yellow-popular logos were recently selling for $150/mbf, three times the price for grade 2 logs in North Carolina. A computerized stand development model was used to examine the profitability of thinning and holding yellow poplar stands for increased diameter and grade. Analyses were done over wide ranges in stand age, site quality, and stocking, at 5% and 10% discount rates. At a 5% discount rate, the maximum net present stumpage value was obtained by thinning in most regimes. Lower stand age, higher initial stocking, and higher site indices favored thin-clearcut regimes over regimes with no initial thinning. At a 10% discount rate, thinning was optimal only at initial age 30 on the highest quality sites at the highest initial stocking. All other combinations of variables favored clearcutting immediately or with a 1O -year delay. Thinning options with net values within 50% of maximum were numerous at a 5% discount rate in younger stands but decrease rapidly as initial age increased. Only a few such options were available at the 10% discount rate. South. J. Appl. For. 14(3):101-103

Flight evaluation of advanced flight control systems and cockpit displays for powered-lift STOL Aircraft

A flight research program was conducted to assess the improvements, in longitudinal path control during a STOL approach and landing, that can be achieved with manual and automatic control system concepts and cockpit displays with various degrees of complexity. NASA-Ames powered-lift Augmentor Wing Research Aircraft was used in the research program. Satisfactory flying qualities were demonstrated for selected stabilization and command augmentation systems and flight director combinations. The ability of the pilot to perform precise landings at low touchdown sink rates with a gentle flare maneuver was also achieved. The path-control improvement is considered to be applicable to other powered-lift aircraft configurations