|
|
|
Pole Banner Durability and the Effects of Wind A banner has the potential to be a sail or airfoil. Sails work best not when wind flows directly against one surface, but when it flows across the sail from one edge to the other, faster across one side than the other, creating lift. Lift is what drives a sailboat along at speeds faster than that of the wind. Lift is also what destroys banners on arms that flex. To combat wind load effects on pole banners, many bracket manufacturers have settled on combinations of aluminum bases, band straps and fiberglass poles, promising to extend banner life by allowing the fiberglass arms to flex under wind pressure. The claim is usually that if the banner flexes to reduce its profile to the wind, it will last longer. Such claims unscientifically avoid accounting for the aerodynamic properties of a piece of fabric which is stretched between two parallel arms. When wind pressure forces the ends of flexible arms to bend toward each other, the outer edge of the banner curves, forming an airfoil. Compared to remaining flat, its airfoil shape exerts more bending force on the brackets and more tearing force on the pocket seams. As the arms flex, the bond between the base of the fiberglass arm and its socket is strained, and can erode and loosen over time. The continuously flexing fiberglass arm can eventually loses its ability to return to straight. The stress on the banner pocket seams is distributed non-uniformly as the banner follows the curve of the bent arm. Eventually, the weakest stitch can give way under its unfair share of wind pressure. The banner may even try to slip off the arm unless tied to the pole with wire or other unsightly hardware. The combination of ripped seams and crooked arms results in the saggy, baggy banner displays that can be seen drooping off poles everywhere. Our business thrives on replacing this type of product. Our steel bracket system concept acknowledges that a banner wants to be an airfoil, but won't let it act like one. Installed or adjusted with one small wrench, our bracket arms remain parallel to each other, and do not yield to the wind or allow the banner to become an airfoil. Our brackets extend banner life by distributing wind load uniformly to all points in the system. In this way, each stitch and bolt shares the load equally and is less likely to fail. Banners typically remain nice and flat, and live to see many days when mounted on our brackets. Many of our brackets are now in their tenth year of continuous use. While our repeat and referral business has grown steadily, we have been fortunate to have not yet had a single serious complaint or a faulty product returned. The success of our product leads us to believe that our brackets are the easiest to install, best looking and longest lasting brackets available anywhere, making them a superior value.
|
|
||||||||||||||||||||||
|
|
||||||||||||||||||||||||
Banner Bracket
Banner Man • 88 Davis Place * Collinsville, IL 62234-1403
Phone: 618-344-0554 • Fax: 618-344-1654
E-mail: ok@bannerbracket.com
Copyright © 2010