Subsonic tests of an all-flush-pressure-orifice air data system

The use of an all-flush-pressure-orifice array as a subsonic air data system was evaluated in flight and wind tunnel tests. Two orifice configurations were investigated. Both used orifices arranged in a cruciform pattern on the airplane nose. One configuration also used orifices on the sides of the fuselage for a source of static pressure. The all-nose-orifice configuration was similar to the shuttle entry air data system (SEADS). The flight data were obtained with a KC-135A airplane. The wind tunnel data were acquired with a 0.035-scale model of the KC-135A airplane. With proper calibration, several orifices on the vertical centerline of the vehicle's nose were found to be satisfactory for the determination of total pressure and angle of attack. Angle of sideslip could be accurately determined from pressure measurements made on the horizontal centerline of the aircraft. Orifice pairs were also found that provided pressure ratio relationships suitable for the determination of Mach number. The accuracy that can be expected for the air data determined with SEADS during subsonic orbiter flight is indicated

The use of the tethered satellite system to perform low density aerothermodynamics studies

The Tethered Satellite System (TSS) is a cooperative space system development activity of the U.S.A. and Italy. It is comprised of the Tether Satellite (TS) and the deployer. Within TSS, the Shuttle Tethered Aerothermodynamic Research Facility (STARFAC) concept has the potential to provide access to vast portions of the upper atmosphere for atmospheric and aerothermodynamic research. The feasibility and capability of the TSS to operate as a continuous open wind tunnel and to perform low density aerothermodynamic studies are investigated. This is accomplished through a modified version of the TS simulation program (SKYHOOK). The results indicate that STARFAC concept is both feasible and practical. The TS can go below 100 km but, if thrust is used, large velocity variation (delta V) maneuvers and an attitude control are required; if a satellite lift is considered, large tether tension is produced and an attitude control is required

Wind-tunnel investigation of a flush airdata system at Mach numbers from 0.7 to 1.4

Flush pressure orifices installed on the nose section of a 1/7-scale model of the F-14 airplane were evaluated for use as a flush airdata system (FADS). Wing-tunnel tests were conducted in the 11- by 11-ft Unitary Wind Tunnel at NASA Ames Research Center. A full-scale FADS of the same configuration was previously tested using an F-14 aircraft at the Dryden Flight Research Facility of NASA Ames Research Center (Ames-Dryden). These tests, which were published, are part of a NASA program to assess accuracies of FADS for use on aircraft. The test program also provides data to validate algorithms for the shuttle entry airdata system developed at the NASA Langley Research Center. The wind-tunnel test Mach numbers were 0.73, 0.90, 1.05, 1.20, and 1.39. Angles of attack were varied in 2 deg increments from -4 deg to 20 deg. Sideslip angles were varied in 4 deg increments from -8 deg to 8 deg. Airdata parameters were evaluated for determination of free-stream values of stagnation pressure, static pressure, angle of attack, angle of sideslip, and Mach number. These parameters are, in most cases, the same as the parameters investigated in the flight test program. The basic FADS wind-tunnel data are presented in tabular form. A discussion of the more accurate parameters is included

Wind tunnel investigation of an all flush orifice air data system for a large subsonic aircraft

The results of a wind tunnel investigation on an all flush orifice air data system for use on a KC-135A aircraft are presented. The investigation was performed to determine the applicability of fixed all flush orifice air data systems that use only aircraft surfaces for orifices on the nose of the model (in a configuration similar to that of the shuttle entry air data system) provided the measurements required for the determination of stagnation pressure, angle of attack, and angle of sideslip. For the measurement of static pressure, additional flush orifices in positions on the sides of the fuselage corresponding to those in a standard pitot-static system were required. An acceptable but less accurate system, consisting of orifices only on the nose of the model, is defined and discussed

Implications of sensory ecology for species coexistence: biased perception links predator diversity to prey size distribution

Inherent to sensory systems is a discrepancy between the perceived and the actual environment. We modelled prey perception in different species of echolocating bats and show that differences in sensory systems can be important for shaping the niches of animals and for structuring animal communities. We argue that sensory specialization can lower interspecific competition by making the same world appear different. We specifically raise the claim that it is important to consider the interaction of sensory bias and the distribution of (prey) resource size. Using a modeling approach we assessed the potential contribution of sensory bias for species coexistence for the example of bat echolocation. We show that even relatively small sensory differences among coexisting species can translate into significant differences in access to food resources, if prey size distribution is skewed towards small prey. Specifically, for the prey size distribution occurring most frequently in nature, differences in sensory access to resources seem large enough to relax competition and facilitate species coexistence. Interaction between sensory bias and prey size distribution in a way that enhances species coexistence may be a general phenomenon not limited to bat echolocation.publishe

Variability in Echolocation Call Intensity in a Community of Horseshoe Bats: A Role for Resource Partitioning or Communication?

Only recently data on bat echolocation call intensities is starting to accumulate. Yet, intensity is an ecologically crucial parameter, as it determines the extent of the bats' perceptual space and, specifically, prey detection distance. Interspecifically, we thus asked whether sympatric, congeneric bat species differ in call intensities and whether differences play a role for niche differentiation. Specifically, we investigated whether R. mehelyi that calls at a frequency clearly above what is predicted by allometry, compensates for frequency-dependent loss in detection distance by using elevated call intensity. Maximum echolocation call intensities might depend on body size or condition and thus be used as an honest signal of quality for intraspecific communication. We for the first time investigated whether a size-intensity relation is present in echolocating bats.We measured maximum call intensities and frequencies for all five European horseshoe bat species. Maximum intensity differed among species largely due to R. euryale. Furthermore, we found no compensation for frequency-dependent loss in detection distance in R. mehelyi. Intraspecifically, there is a negative correlation between forearm lengths and intensity in R. euryale and a trend for a negative correlation between body condition index and intensity in R. ferrumequinum. In R. hipposideros, females had 8 dB higher intensities than males. There were no correlations with body size or sex differences and intensity for the other species.Based on call intensity and frequency measurements, we estimated echolocation ranges for our study community. These suggest that intensity differences result in different prey detection distances and thus likely play some role for resource access. It is interesting and at first glance counter-intuitive that, where a correlation was found, smaller bats called louder than large individuals. Such negative relationship between size or condition and vocal amplitude may indicate an as yet unknown physiological or sexual selection pressure

Pressure distributions obtained on a 0.04-scale and 0.02-scale model of the Space Shuttle Orbiter's forward fuselage in the Langley 20-inch Mach 6 air tunnel

Results from pressure distribution tests on 0.04-scale and 0.02-scale models of the forward fuselage of the Space Shuttle Orbier are presented without analysis. The tests were completed in the Langley 20-Inch Mach 6 Tunnel. The 0.04-scale model was tested at angles of attack from 0 to 35 and angles of sideslip from 0 to -4. The 0.02-scale model was tested at angles of attack from -10 to 45 and angles of sideslip from 0 to -4. The tests were conducted in support of the development of the Shuttle Entry Air Data System (SEADS). In addition to modeling the 20 SEADS pressure orifices, the wind-tunnel to models were also instrumented with orifices to match Development Flight Instrumentation (DFI) port locations currently existing on the Space Shuttle Orbiter Columbia (OV-102). This DFI simulation had provided a means for comparisons between reentry flight pressure data and wind-tunnel data

Pressure distributions obtained on a 0.04-scale and 0.02-scale model of the Space Shuttle Orbiter's forward fuselage in the Langley continuous flow hypersonic tunnel

Results from pressure distribution tests on 0.04-scale and 0.02-scale models of the forward fuselage of the Space Shuttle Orbiter are presented without analysis. The tests wre completed in the Langley Continuous Flow Hypersonic Tunnel (CFHT). The 0.04-scale model was tested at angles of attack from -5 deg to 45 deg and angles of sideslip from -3 deg to 3 deg. The 0.02-scale model was tested at angles of attack from -10 deg to 45 deg and angles of sideslip from -5 deg to 5 deg. The tests were conducted in support of the development of the Shuttle Entry Air Data System (SEADS). In addition to modeling the 20 SEADS pressure orifices, the wind-tunnel models were also instrumented with orifices to match Development Flight Instrumentation (DFI) port locations currently existing on the Space Shuttle Orbiter Columbia (OV-102). This DFI simulation has provided a means for comparisons between reentry flight pressure data and wind-tunnel data

Forming peculiarities and manifestation of tectonic faults in soft rocks

Features of distribution of tectonic structures in soft rocks confirm the presence of horizontal tectonic forces in the formation of faults and are based on the manifestation of their morphological features. Linear dependences of the amplitude on the length of tectonic dislocation in the area of wedging were obtained as a result of mathematical processing of the experimental data. Actual position of the crossing lines of fault plane with the seam were considered while studying the distribution of co-fault fracturing. Analysis of the data confirms that the distribution of faulting has an undulating character. Analysis of observations showed that the deviation of the crossing line of fault plane with the seam from the middle line is subject to the normal law of random variable distribution. Thus, the studies and the obtained results allow planning mining operations assessing the utility while developing fault areas

Aeroassist Flight Experiment (AFE)

Information is given in viewgraph form on the Aeroassist Flight Experiment (AFE), an experiment with the objective of investigating critical vehicle design and environmental technologies applicable to the design of aeroassisted space transfer vehicles. Information is given on design, simulation, flight regime, mission requirements and objectives, instrumentation, and the project schedule