J. Weissinger

Bio: J. Weissinger is an academic researcher from National Advisory Committee for Aeronautics. The author has contributed to research in topics: Wing twist & Lift (force). The author has an hindex of 1, co-authored 1 publications receiving 216 citations.

The Lift Distribution of Swept-Back Wings

Abstract: Two procedures for calculating the lift distribution along the span are given in which a better account is taken of the distribution of circulation over te area than in the Prandtl lifting-line theory. The methods are also applicable to wing sweepback. Calculated results for the two methods were in agreement.

DRAG DUE TO LIFT: Concepts for Prediction and Reduction

Abstract: ▪ Abstract This article describes some of the fundamental ideas underlying methods for induced-drag prediction and reduction. A review of current analysis and design methods, including their development and common approximations, is followed by a survey of several approaches to lift-dependent drag reduction. Recent concepts for wing planform optimization, highly nonplanar surfaces, and various tip devices may lead to incremental but important gains in aircraft performance. Focusing on relatively high-aspect-ratio subsonic wings, the review suggests that opportunities for new concepts remain, but the greatest challenge lies in their integration with other aspects of the system.

Optimization of Perching Maneuvers Through Vehicle Morphing

Abstract: This paper discusses the development and optimization of trajectories designed to bring a long endurance unmanned aerial vehicle from a loitering state to a planted landing referred to as a perching maneuver. These trajectories are developed for attached, partially stalled, and fully stalled flow regimes. The effects of nonlinear aerodynamics and vehicle shape reconfiguration are shown to lessen the initial distance from the landing site required to initiate the maneuver, reduce the spatial bounds on the trajectory, and decrease the required thrust for the maneuver. The aerodynamics are modeled using empirical and analytical methods in both attached and separated flow regimes. Optimal solutions of varying thrust-to-weight ratio and center-of-gravity location are compared. Additionally, perching trajectories that compare morphing versus fixed configuration and stalled versus unstalled aircraft are presented to demonstrate the effects of relaxed constraints on vehicle geometry and flight envelope. Control effort is also evaluated in these simulations; specifically, the available control for disturbance rejection is compared for morphing versus fixed-configuration aircraft. The results of these comparisons show that morphing increases the controllability of the aircraft throughout the maneuver as well as decreases the cost of the optimal perching trajectory.

Full Configuration Drag Estimation

Abstract: Accurate drag estimation is critical in making computational design studies. Drag may be estimated thousands of times during a multidisciplinary design optimization, and computational fluid dynamics is not yet possible in these studies. The current model has been developed as part of an air-vehicle conceptual-design multidisciplinary design optimization framework. Its use for subsonic and transonic aircraft configurations is presented and validated. We present our parametric geometry definition, followed by the drag model description. The drag model includes induced, friction, wave, and interference drag. The model is compared with subsonic and transonic isolated wings, and a wing/body configuration used previously in drag prediction workshops. The agreement between the predictions of the drag model and test data is good, but lessens at high lift coefficients and high transonic Mach numbers. In some cases the accuracy of this drag estimation method exceeds much more elaborate analyses.