Minke whales (Balaenoptera acutorostrata) are the smallest member of balaenopterid whales and little is known of their kinematics during feeding maneuvers. These whales have narrow and elongated flippers that are small relative to body size compared to related species such as right and gray whales. No experimental studies have addressed the hydrodynamic properties of minke whale flippers and th...

The flight paths and wingbeat patterns of 39 barn swallows (Hirundo rustica) and 26 house martins (Delichon urbica) were recorded by tracking radar during the spring migration. Depending mostly on flight angle, hirundines performed anything from continuous flapping flight during climbing to single pulse-like wing beats during descent. Unlike most other passerines, hirundines rarely showed regul...

A method of scaling is described that easily converts the aeroelastic equations of motion of a full-sized aircraft into ones of a wind-tunnel model. To implement the method, a set of rules is provided for the conversion process involving matrix operations with scale factors. In addition, a technique for analytically incorporating a spring mounting system into the aeroelastic equations is also p...

This report describes the formulation of a model of the dynamic behavior of the Benchmark Active Controls Technology (BACT) wind tunnel model for active control design and analysis applications. The model is formed by combining the equations of motion for the BACT wind tunnel model with actuator models and a model of wind tunnel turbulence. The primary focus of this report is the development of...

The present work is devoted to develop a numerical wind tunnel to study the local turbulent flow fields over complex topography by using large eddy simulation. Firstly, the mean and turbulence flow over flat terrain and that over a steep 3-dimensional circular hill were simulated and the accuracy of these computations was assessed by comparing the results with those from the experiment. Then th...

Tonal, non-vocal sounds are widespread in both ordinary bird flight and communication displays. We hypothesized these sounds are attributable to an aerodynamic mechanism intrinsic to flight feathers: aeroelastic flutter. Individual wing and tail feathers from 35 taxa (from 13 families) that produce tonal flight sounds were tested in a wind tunnel. In the wind tunnel, all of these feathers could...

An investigation is presented of Mach 12 flow over a wind tunnel model of a tether connecting an aerobraking spacecraft to an inflatable drag device. The study was undertaken to support numerical simulations employed in the design of a “ballute” (balloon-parachute) aerobraking device currently being developed by Ball Aerospace and NASA. The attachment point of the tether to the ballute is subje...

An automatic rotor trim control system was developed and successfully used during a wind tunnel test of a full-scale UH-60 rotor system with Individual Blade Control (IBC) actuators. The trim control system allowed rotor trim to be set more quickly, precisely and repeatably than in previous wind tunnel tests. This control system also allowed the rotor trim state to be maintained during transien...

This paper explored the effect of building shape on the wind-induced response of a structure through a comprehensive investigation of wind tunnel studies performed at Rowan Williams Davies and Irwin, Inc. (RWDI). The study focused on buildings with foot prints of square, circular, triangular, rectangular and elliptical shapes. Seed buildings were selected from an inventory of structures previou...

A trisonic wind tunnel has been modified to improve its flow quality when operating at transonic speeds through perforated walls and side suctions. The usefulness of such a perforated wall, already known, is reduction of the blockage effect as well as the shock elimination. Two types of perforated walls have been used in this investigation. The first wall had a porosity of about 22% and the hol...