What is it, and what does it do?
Almost every time someone has their aircraft reupholstered I hear, "I wish we could leave out the windlace, but that darn cabin is already too drafty." They want to leave out the windlace because it was one of the first things to wear out on the old interior. Therefore, they think leaving it out will make the new interior last longer. But they are afraid that without the windlace the cabin will be draftier. I dont know if an interior without windlace lasts longer or not. However, I know that keeping out the wind is not the function of windlace.
The most misunderstood component of an aircraft interior is windlace. What is windlace? Its essentially an oversized, spongy welt. Its about a half-inch in diameter, and can be found occupying the outer perimeter of the door opening on many general aviation aircraft. Typical windlace construction is simply a foam core, about a half-inch in diameter, covered with vinyl, cloth, or leather. Sometimes, its just a vinyl cylinder. The flap of extra material along the edge is used to secure the windlace in place.
The purpose of windlace is to hide gaps. Thats right, its purely cosmetic. Take a look around and youll see windlace at work in a variety of applications. In restaurants it hides the gaps between the booths. In boats it hides the gap between the seats and the side of the boat. In cars it hides the same gaps that it hides in aircraft, the gap between the interior trim panel and the surface to which they attach, and the gap between the door and doorframe.
This gap between the side panel and the doorpost looks bad. You can see the back of the panel, and the metal surface the panel is supposed to be covering.
The windlace hides the gap and nicely finishes the area where the panel meets the doorpost.
When the door is closed there is a small gap between the door and the doorpost.
With the windlace installed, the gap between the door and doorpost is hidden. The effect of the windlace is more pronounced when the door upholstery goes right to the edge of the door. Then the windlace provides continuity of upholstery where otherwise there would be a gap.
If it doesnt keep out the weather, rain, or wind, why do they call it "wind" lace? Upholstery techniques were first applied to furniture. Then, as the automobile matured, furniture upholstery techniques were applied to auto interiors. Eventually, automotive upholstery evolved into a separate discipline. As aircraft developed, their upholstery needs were more closely related to automotive upholstery techniques than furniture techniques. The adoption of automotive upholstery techniques to aircraft applications is where we find the answer.
In the early days of coach building some auto bodies were made of wood, and even more had wooden frames covered with sheet metal. Windows were installed in these auto bodies in about the same way windows were installed in houses. The wooden frame was recessed to accept the glass, and wooden slats were installed to hold the glass in place.
When it came time to install the upholstery, the material was tacked to the wooden framework. Where the material met the window, it was tacked to the slats that held the window in place. As you might imagine, the raw edge of the material with a bunch of tacks showing looked rather crude. To put a pretty face on this ugly situation they attached a narrow strip of decorative material, known as lace, on top of the tacks. This lace covered the tack heads and the raw edge of the material, and became commonly referred to as window lace.
As time went on, window lace became known as windlace. The building of automotive bodies continued to evolve. The wood was replaced with metal and the area around the window now had a metal molding. The gap between the window and the molding was filled with an oversized, spongy welt. This new technique retained the old name, "windlace." The evolution of interior techniques continued, and eventually windlace was used to finish the edges around the door openings too. At this point we have a term, and a technique, that has no obvious connection to its origin, or current application.
As manufacturing processes improved, and interior fashion changed, the perceived need for windlace has been reduced. Some of todays aircraft, as well as most modern cars, have no trace of windlace.
When the time comes for your aircraft interior restoration you can decide to retain the windlace based on whether or not you feel the gaps need to be hidden, not whether or not the cabin is too drafty.
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