The cutting pattern of a fabric panel evolves in the model, and the floor & ceiling plans show the running length of each panel-to-be. If the difference in length between the upper edges of a panel and the edges on the ground is less than 1/3, it will be absorbed in the stretching. But if the difference is greater, either fabric wedges will have to be inserted in the longer edge, or the sides of segments tapered to make up the difference (shown in drawings). When patterning the fabric for models, the width of a ply of the fabric to be used in the installation must be scaled, and when the pattern calls for shaping, the more complex shapes are cut out of paper, and traced on the fabric before cutting. After the segments are cut & sewn together to form a panel, it is stretched in the model frame, the edges fastened with pushpins. The final cutting pattern (developed in the model) is kept for future reference.
Note 1: The fabric is cut unstretched; all patterns must align with the fabric's running length (not to be placed randomly); and when cutting patterns for models, allow 1/8" or 1/4" extra fabric all around for seams & attachments.
Note 2: Trying to eliminate these tedious steps of sectioning & sewing together small fabric segments and stretching instead a long strip of fabric as far as it will go, produces disastrous surprises when such a membrane is enlarged.
Note 3: When surface configurations are arrived at in a scale model by stretching fabric, and then plotted on a computer for patterning (intended for enlargement), the resulting cutting patterns are applicable only to rigid materials or stiffened industrial fabrics. The sections, put together to form a wide span fabric structure, produce a surface that simulates the appearance of a membrane in tension but not its behavior. Since such membranes are "draped" over rigid supports, and the enclosure is kept in shape by tension applied at the outer edges, the inflexible surface generates powerful shearing stresses. This suffices to illustrate why tensile shapes, enlarged by means of modern technologies and translated into modern materials, invite a disproportional investment of energy in resisting the elements.
see The 20th Century Environmant
