interior facing edge 46 as is illustrated in fig4 this doubly tapered edge 46 minimizes turbulence created by the airflow around the straight edge portions 45 fabrication is completed by installation of the panels 33 by bolting the upturned edges of the perforated sheets 34 along with the reinforcement strips 37 to the edge portions 45 as described above and illustrated in fig4 because the entire turbulence control structure 10 is cantilevered from the vertical support shafts 24 and 25 greater stress bears on the area of the dome closest to the support shafts 24 and 25 to keep overall weight to a minimum and to keep the center of gravity near the base ring 17 the frame material was chosen as a function of the frame location in the dome polygonal frame members 44 nearest the base ring 17 are constructed of one eighth inch stainless steel polygonal frame members 44 in the middle one third of the structure 10 are constructed of one eighth inch aluminum plate and the frame members 44 in the forward third of the structure 10 are constructed of one tenth inch aluminum plate by minimizing the weight and size of the frame members 44 and by using the means of fabrication described above the total area of the dome surface occupied by the frame 32 is only 2 9 of the total spherical area of the turbulence control structure 10 this represents a significant improvement over previous turbulence control structures wherein the total frame area was typically.