Investigation of a moving-model technique for measuring ground effect

A ground-based testing technique is under development for the measurement of dynamic or time-dependent ground effects which may be present during aircraft approach and landing. The technique utilizes a model moving horizontally over an upwardly-inclined ground plane to simulate rate of descent. Results were obtained in the Langley Research Center (LaRC) Vortex Research Facility (VRF) for a generic 60 delta wing and for an F-18 configuration, both with and without thrust reversing, at forward speeds up to 100 ft/sec. These same models and support hardware were also tested in the LaRC 14 by 22 Foot Subsonic Tunnel at identical conditions (but without rate of descent) with and without a moving-belt ground plane to obtain data for comparison

An assessment of ground effects determined by static and dynamic testing techniques

A new testing technique was developed wherein the rate of descent can be included as a parameter in ground effects investigations. This technique simulates the rate of descent by horizontal motion of a model over an inclined ground board in the Langley Vortex Research Facility (VRF) During initial evaluations of the technique, dynamic ground effects data were obtained over the inclined ground board, steady state ground effects data were obtained over a flat portion of the ground board, and the results were compared to conventional static wind tunnel ground effect data both with and without a moving belt ground plane simulation. Initial testing and analysis led to the following conclusions: the moving belt ground plane had little effect on static ground effects for the configurations tested unless thrust reversers were employed; in general, rate-of-descent reduced ground effects to the point that for reversed thrust cases an expected loss of lift due to ground effects was eliminated at approach conditions; and, in general, the steady state results from the VRF matched static results obtained from the wind tunnel once the flow field stabilized over the flat portion of the ground board

Cross-training Christians for rural servant-leadership : an exploration of the role of a congregation in nurturing leadership in the community of Wessington Springs, South Dakota

This study explores the relationship between what is learned and experienced in the Christian faith community and people’s involvement in collaborative leadership within the rural community of Wessington Springs, South Dakota. The author makes use of Martin Luther’s theology of the cross and his teachings regarding Christian vocation, including the calling of parents as family leaders. This approach to leadership development employs a missional ecclesiology, with attention to the Triune God’s transformative, sending work in the world, and examines contributions from knowledge about civil society and human and social capital. Asset mapping is examined as a tool for leadership development

HSCT high lift system aerodynamic requirements

The viewgraphs and discussion of high lift system aerodynamic requirements are provided. Low speed aerodynamics has been identified as critical to the successful development of a High Speed Civil Transport (HSCT). The airplane must takeoff and land at a sufficient number of existing or projected airports to be economically viable. At the same time, community noise must be acceptable. Improvements in cruise drag, engine fuel consumption, and structural weight tend to decrease the wing size and thrust required of engines. Decreasing wing size increases the requirements for effective and efficient low speed characteristics. Current design concepts have already been compromised away from better cruise wings for low speed performance. Flap systems have been added to achieve better lift-to-drag ratios for climb and approach and for lower pitch attitudes for liftoff and touchdown. Research to achieve improvements in low speed aerodynamics needs to be focused on areas most likely to have the largest effect on the wing and engine sizing process. It would be desirable to provide enough lift to avoid sizing the airplane for field performance and to still meet the noise requirements. The airworthiness standards developed in 1971 will be the basis for performance requirements for an airplane that will not be critical to the airplane wing and engine size. The lift and drag levels that were required to meet the performance requirements of tentative airworthiness standards established in 1971 and that were important to community noise are identified. Research to improve the low speed aerodynamic characteristics of the HSCT needs to be focused in the areas of performance deficiency and where noise can be reduced. Otherwise, the wing planform, engine cycle, or other parameters for a superior cruising airplane would have to be changed

Low-speed longitudinal and lateral-directional aerodynamic characteristics of the X-31 configuration

An experimental investigation of a 19 pct. scale model of the X-31 configuration was completed in the Langley 14 x 22 Foot Subsonic Tunnel. This study was performed to determine the static low speed aerodynamic characteristics of the basic configuration over a large range of angle of attack and sideslip and to study the effects of strakes, leading-edge extensions (wing-body strakes), nose booms, speed-brake deployment, and inlet configurations. The ultimate purpose was to optimize the configuration for high angle of attack and maneuvering-flight conditions. The model was tested at angles of attack from -5 to 67 deg and at sideslip angles from -16 to 16 deg for speeds up to 190 knots (dynamic pressure of 120 psf)

Evaluation of Four Advanced Nozzle Concepts for Short Takeoff and Landing Performance

Four advanced nozzle concepts were tested on a canard-wing fighter in the Langley 14- by 22-Foot Subsonic Tunnel. The four vectoring-nozzle concepts were as follows: (1) an axisymmetric nozzle (AXI); (2) an asymmetric, load balanced exhaust nozzle (ALBEN); (3) a low aspect ratio, single expansion ramp nozzle (LASERN); and (4) a high aspect ratio, single expansion ramp nozzle (HASERN). The investigation was conducted to determine the most suitable nozzle concept for short takeoff and landing (STOL) performance. The criterion for the best STOL performance was a takeoff ground roll of less than 1000 ft. At approach, the criteria were high lift and sufficient drag to maintain a glide slope of -3 to -6 deg with enough pitching-moment control from the canards. The test was performed at a dynamic pressure of 45 lb/sq ft and an angle-of-attack range of 0 to 20 deg. The nozzle pressure ratio was varied from 1.0 to 4.3 at both dry power and after burning nozzle configurations with nozzle vectoring to 60 deg. In addition, the model was tested in and out of ground effects. The ALBEN concept was the best of the four nozzle concepts tested for STOL performance

Lost conversations: finding new ways for black and white Australians to lead together

It\u27s time for a game-changer in how black and white Australians relate.   The difficulties we have in coming together—to talk, to work, to lead change—are core to our challenge to reconcile, as a country. But if we want to shift the status quo, if we want to lead change on entrenched Indigenous disadvantage, we don\u27t need another program, initiative or money to try and \u27fix\u27 the problem. We need to start having a different conversation.  The result of two years experience working together as part of a Social Leadership Australia initiative, Lost Conversations brings together the diverse perspectives and personal stories of five Aboriginal and four non-Indigenous authors, all with first-hand knowledge of what happens when black and white Australians come together to try and work on change.  Lost Conversations asks the questions and starts the conversations that we daren\u27t have in Australia ... until now:  What is \u27black\u27 power? What is \u27white\u27 power?  What qualifies someone to lead in this cross-cultural space?  Why is this so hard to talk about?  Can we start to name these things and try to shift the status quo?  Can we change?  Should we?  &nbsp

Greece is insolvent but illiquid. CEPS Commentary, 18 June 2015

In a new CEPS Commentary, Paul De Grauwe argues that the Greek government is solvent but is trapped in a liquidity dilemma in which cannot find liquidity because markets believe it cannot find liquidity. He then explores the role of the European Central Bank in this self-fulfilling problem and ask specifically whether its outright monetary transactions (OMT) programme, introduced in September 2012, should be used to ease the constraints on Greece

De Novo Pudendal Neuropathy After TOT-O Surgery for Stress Urinary Incontinence

Complications from needle placement and exit during a TOT procedure exist and must be considered when placing the needle through the area of the obturator fossa