Steven X. S. Bauer

Simple and Low-Cost Aerodynamic Drag Reduction Devices for Tractor-Trailer Trucks

Three simple, low cost aerodynamic drag reduction devices have been developed for application to the trailer of a tractor-trailer truck. The three devices have undergone extensive operational testing where they have amassed over 85,000 miles of use. These technologies have shown a combined fuel savings of 10% at an average speed of 47.5 mph. This improvement in fuel economy correlates to an equivalent drag reduction of approximately 30% with a corresponding drag coefficient of 0.45. Observations and anecdotal evidence from the test activity have shown that the addition of these devices to the trailers has not had a negative impact on either the operational utility of the trailers or the maintenance procedures and requirements.

Flying wings/flying fuselages

The present paper has documented the historical relationships between various classes of all lifting vehicles, which includes the flying wing, all wing, tailless, lifting body, and lifting fuselage. The diversity in vehicle focus was to ensure that all vehicle types that map have contributed to or been influenced by the development of the classical flying wing concept was investigated. The paper has provided context and perspective for present and future aircraft design studies that may employ the all lifting vehicle concept. The paper also demonstrated the benefit of developing an understanding of the past in order to obtain the required knowledge to create future concepts with significantly improved aerodynamic performance.

Assessment of passive porosity with free and fixed separation on a tangent ogive forebody

Subsonic wind tunnel tests were performed on solid and porous (22 percent) 5.0-caliber forebody models to assess the effect of free and fixed cross-flow separation on the effectiveness of passive porosity. The effectiveness of passive porosity to control the local pressure loading for forced cross-flow separation is found to be similar to that observed for the free cross-flow separation condition. It is also found that the effectiveness of passive porosity is significantly enhanced in the presence of large positive pressures on the porous surface.

Configuration trade and code validation study on a conical hypersonic vehicle

A study has been conducted on a generic wing-cone transatmospheric vehicle at Mach numbers form 2.5 to 4.5. The objectives of the study were to experimentally define the aerodynamic characteristics of the vehicle and evaluate several computational aerodynamic prediction methods through comparison with the experimental results. The baseline wing-cone configuration fuselage consisted of a 5 deg half-angle cone forebody, cylindrical midbody, and 9 deg truncated cone afterbody. The 4-percent-thick diamond airfoil wing had an aspect ratio of 1. Several configuration variables were investigated to provide trade information on canard, wing-position and incidence, vertical tail, and nose bluntness effects. Results of the study show that wing-position and wing-incidence effects on the longitudinal aerodynamic characteristics can be significantly influenced by wing-body interference. The use of positive wing incidence to provide favorable forebody orientation for possible inlet performance improvement is accompanied by trim drag and lift-drag ratio penalties. The lateral-directional stability characteristics were strongly influenced by the location of the vertical tails. The higher-order full-potential method provided better estimates of the aerodynamic characteristics than either the linearized supersonic potential method or the tangent-cone/tangent-wedge/shock-expansion on method.

A natural flow wing design employing 3-D nonlinear analysis applied at supersonic speeds

A wing-design study has been conducted on a 65-deg-swept leading-edge delta wing in which a near-conical geometry was employed to take advantage of the naturally occurring conical flow which arises over such a wing in a supersonic flow field. Three-dimensional nonlinear analysis methods were used in the study. In preliminary design, wing planform, design conditions, and near-conical concept were derived and a baseline standard wing (conventional airfoil distribution) and a baseline near-conical wing were chosen. During the initial analysis, a full-potential solver was employed to determine the aerodynamic characteristics of the baseline standard delta wing and the near-conical delta wing. Modifications due to airfoil thickness, leading-edge radius, and camber were then applied to the baseline near-conical wing. The final design employed a Euler solver to analyze the best wing configurations found in the initial design, and to extend this study to develop a more refined wing. Benefits due to each modification are discussed, and a final natural flow wing geometry is chosen and its aerodynamic characteristics are compared with the baseline wings.

Evaluation of a three-dimensional empirically derived wing at supersonic speeds

A novel wing design concept is introduced which takes advantage of the existence of conical flow at supersonic speeds. The present wing design concept is to create a near conical wing geometry by redistributing airfoils in a spanwise direction. In addition, a set of graphs which review the supersonic aerodynamics of delta wings have been employed to select a design wing sweep and Mach number. An iteration through the wing design logic resulted in the selection of a 65 deg swept delta wing and a design Mach number of 1.62. Theoretical analysis was performed with a nonlinear full-potential analysis method to assess the merits of the wing design approach. The analysis showed large reductions in drag due to lift compared to delta wings configured with traditional thickness and airfoil distributions.

Creativity and creative teams

A review of the linkage between knowledge, creativity, and design is presented and related to the best practices of multidisciplinary design teams. The discussion related to design and design teams is presented in the context of both the complete aerodynamic design community and specifically the work environment at the NASA Langley Research Center. To explore ways to introduce knowledge and creativity into the research and design environment at NASA Langley Research Center a creative design activity was executed within the context of a national product development activity. The success of the creative design team activity gave rise to a need to communicate the experience in a straightforward and managed approach. As a result the concept of creative potential its formulated and assessed with a survey of a small portion of the aeronautics research staff at NASA Langley Research Center. The final section of the paper provides recommendations for future creative organizations and work environments.