Air forces on airfoils moving faster than sound

We are undertaking the task of computing the air forces on a slightly cambered airfoil in the absence of friction and with an infinite aspect ratio. We also assume in advance that the leading edge is very sharp and that its tangent lies in the direction of motion

Experiments on airfoils with trailing edge cut away

Airfoils with their trailing edge cut away are often found on aircraft, as the fins on the hulls of flying boats and the central section of the wings for affording better visibility. It was therefore of some interest to discover the effect of such cutaways on the lift and drag and on the position of the center of pressure. For this purpose, systematic experiments were performed on two different airfoils, a symmetrical airfoil and an airfoil of medium thickness, with successive shortenings of their chords

Analysis of saturation flows at single, dual and triple left-turn lanes

The primary objective of the research presented in the dissertation, Analysis of Saturation Flows at Single, Dual and Triple Left-Turn Lanes, is to gain a better understanding of the operational characteristics of single and multiple left-turn lanes as compared to adjacent through-lanes on the same intersection approach. The findings of this study are based on average saturation flow headways as observed between the 4th and 8th vehicles within a saturation queue discharge. These observations were made for left turn movements at signalized intersections with protected left-turn phases. The findings of this study are based on field measurements taken at 62 individual intersection approaches located on major arterial streets throughout the Las Vegas Metropolitan Area of Nevada outside the Central Business District of the urbanized community. The field observations are from 23 single, 36 dual and 3 triple left-turn lane intersection approaches comprised of 35 individual intersection sites. The collected saturation flow data contained in this study for analysis represents a total of 3,662 time observations of four vehicles each or a total of 14,648 individual passenger vehicles. The intersection sites were selected to be comparable among each other for geometric and operational conditions as well as driver behavior; The findings of this study support the 1994 Highway Capacity Manual suggested ideal through-lane saturation flow rate of 1900 (pcphgpl). However, the field observations suggest that the left-turn factor for single left-turn lanes with protected left-turn signal phasing should be 1.0 and dual left-turn lanes should be a minimum of 0.98 per Lane The results represent a significant increase over the suggested left-turn factor of 0.95 as recommended within the 1994 Highway Capacity Manual. The triple left-turn lane observations were found to continue to support an average left-turn factor of 0.95. These observations should be of particular interest to transportation engineers and planners who are responsible for the evaluation and development of cost-effective alternatives to improve at-grade signalized intersection capacities as the results indicate higher than expected left-turn capacities relative to the adjacent through lanes

Removing Boundary Layer by Suction

Through the utilization of the "Magnus effect" on the Flettner rotor ship, the attention of the public has been directed to the underlying physical principle. It has been found that the Prandtl boundary-layer theory furnishes a satisfactory explanation of the observed phenomena. The present article deals with the prevention of this separation or detachment of the flow by drawing the boundary layer into the inside of a body through a slot or slots in its surface

Drag measurements of two thin wing sections at different index values

It is stated that the index value 6000, as found in normal tests of wing sections with a 20 cm chord, falls in the same region where the transition of laminar to turbulent flow takes place on thin flat plates. It is to be expected that slightly cambered, thin wing sections will behave similarly. The following test of two such wing sections were made for the purpose of verifying this supposition

Present and Future Problems of Airplane Propulsion

Some of the problems considered in this report include: thermodynamics of surface friction, application of thick wing sections, special applications of controllable propellers, and gas turbines for aircraft

Factors Contributing to Elite Athletes' Mental Health in the Junior-to-Senior Transition: A Mixed Methods Study.

The goals of this study were to examine factors that may affect the mental health of elite athletes during their junior-to-senior transition and to explore the types and frequency of facilitators and challenges athletes encounter during this transition. Using a cross-sectional, embedded QUAN(qual) mixed methods study design, we surveyed two samples for the study goals. All participants completed demographic data (e.g., gender, age, sports). Sample one (N = 394, Mage = 18.46 years, SD = 2.2) consisted of current transitioning athletes which completed questionnaires on stress, anxiety, depression, well-being, self-compassion, and social support. Mediation and moderation analyses revealed that stress leads to resource depletion, and that self-compassion can be an important resource for young athletes to draw upon to maintain their mental health. Regarding social support results were less conclusive. Sample two (N = 371, Mage = 27.70 years, SD = 8.3) consisted of athletes that have passed the transition. They responded to open questions about helpful strategies and challenges faced during their junior-to-senior transition, which were analyzed using thematic content analysis. Results showed that during the junior-to-senior transition, external resources were more frequently mentioned than internal resources when it came to facilitators. Furthermore, external challenges were perceived as hindering more frequently than internal challenges. These findings can guide practitioners by providing potential starting points for improving the mental health of transitioning elite athletes, as well as information on helpful strategies and barriers during the transition

Aeronautical education and research at the Swiss Institute of Technology in Zurich

Progress in the scientific and practical fields of aviation has caused the Swiss Institute of Technology to organize lectures and practical training courses in all three branches of aeronautics and to found centers of scientific research, laboratories, etc., in order to supply the government and industries with scientifically and technically trained engineers

Experiments with an Airfoil from which the Boundary Layer Is Removed by Suction

Our attempts to improve the properties of airfoils by removing the boundary layer by suction, go back to 1922. The object of the suction is chiefly to prevent the detachment of the boundary layer from the surface of the airfoil. At large angles of attack, such detachment prevents the attainment of the great lift promised by the theory, besides greatly increasing the drag, especially of thick airfoils. This report gives results of those experiments