Aces High Bulletin Board
General Forums => The O' Club => Topic started by: DREDger on April 23, 2010, 01:18:14 PM
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The other day I saw a slow flying airplane with one of those advertisement banners in trail. Got me wondering how do they keep those banners from twisting or flapping uncontrollably.
You figure that the banner is connected by a single cable to the tail of the plane. From that single cable you can see it split to two, one holding the upper and the other the lower part of the banner.
What keeps it then from just twisting around? Perhaps the lower part of the banner is weighted, and the top has an airfoil to keep it up?
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Stall limiter?? :bolt:
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So how do we get such a huge banner into the sky? If the banner were attached to the plane before it took off, this would cause two problems. First, the banner would drag across the runway and get damaged. Second, The drag of the huge banner would make it more difficult to get off the ground and this means the banner would drag even longer.
Getting the airplane banner into the sky takes a great deal of skill. But the huge success of aerial advertising makes it worth the trouble. First, the airplane takes off with a device called a “grapnel hook” hanging in the window. The other end is attached to the tail of the airplane by either rope or cable.
When the airplane is safely off the ground, the pilot unhooks the device from the window, letting it trail behind the plane. On the ground the banner or billboard is folded up with a lead pole in front. A harness is attached to the lead pole. Then a pick up rope is attached to a loop of rope that is attached between two poles about five or six feet off the ground.
Now the plane circles around and, with the hook dragging below the plane and flying at 80 miles an hour, the pilot heads straight for the two poles. As he reaches them, he throttles the engine and pulls back on the stick, causing the plane to soar upward at a steep angle. The hook snags the loop of rope, which pulls the banner up, off the ground and into the sky. What if he misses? Then he circles around and tries it again.
But how does the banner stay upright and not, like a kite, spiraling in the wind? First, the tail end of heavy billboards or banners has tiny parachutes that catch the wind and keep it straight. Then the bottom has weights that keep that edge closest to the ground. The letters are usually seven feet tall and the banner might be up to fifty letters long. So everything must be planned just right so that the drag is not too great or too little.
Hope that helps some.
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http://video.google.com/videoplay?docid=-1754392853408472822#
http://video.google.com/videoplay?docid=-1754392853408472822#docid=1629852017280017615
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Do a search for "aerial banners tiger woods." :D
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When I first started at Morristown, I had a couple of pilot friends who built hours in Citabrias doing
banner towing. Apparently they fly just above stall speed and it makes for a long day. The other thing
that caught my attention is that when they were cruising just offshore, they'd pray the engine held out
as they could see very large sharks just outside the beaches!
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got some brass there