Anzani A 2 Radial 3 Engine: Fabricating Missing Aluminum Intake Elbows

The Anzani Model A 2 was introduced in 1910 and was one of the earliest air-cooled stationary radial type aircraft engines. This type of engine powered several aircraft, including the Bleriot XI and Deperdussin monoplane.

Recently, we completed conservation on the Museum’s Anzani A 2, which will go on display in the upcoming Early Flight gallery, part of the transformation of the exhibitions in our National Mall location. The Museum’s Anzani A 2 was an incomplete example of this engine; it was missing the cast aluminum intake elbows, rockers arms, and push rod assemblies on each cylinder. While the engine was being treated, fabrication specialists in the Mary Baker Engen Restoration Hanger endeavored to recreate these missing components so that the engine could be displayed in a more complete and accurate state.

With no original parts to use as models for their replacements, welder fabricator Kenny Mills had to rely on images he found of complete Anzani A 2 engines. He was able to scale his fabrication plans using these photos, determining the appropriate size, shape, and construction of each part he and machinist Gary Gordon would collaboratively make.

The fabrication of each missing engine component has its own complex and unique process, so we will only focus on the aluminum intake elbows in this blog. Gordon began fabrication by milling a solid billet of aluminum into the basic shape of the elbows using his Bridgeport mill. He also drilled and tapped the bottom of each rough piece, allowing Mills to thread a holding post into each so that he could clamp them in a vise. This allowed him to work all the way around the rough milled elbows as he continued to shape them into their final form.

Using a grinder and file, Mills shaped the elbows by hand, constantly checking his work against a set of contour gauges he had cut out. Once the final form was achieved, he sanded and polished each part until there were no flat spots. It was extremely challenging to create three identical parts by hand in this manner.

Although extremely beautiful, the highly polished elbows created by Mills and Gordon didn’t quite look the part at this point in the process. The original intake elbows were cast aluminum and therefore had a very characteristic appearance. To achieve this casted look, Kenny took the three elbows outside and threw them against gravel. Roughing the parts gave them the same kind of imperfections and pits that would be found on the original cast aluminum parts.

To match the aged and oxidized appearance of the other parts on the Museum’s Anzani A 2, dirt and black shoe polish was ground into the crevices and pits of each elbow.

With the newly fabricated aluminum intake elbows installed alongside the newly fabricated rocker arms and push rod assemblies, the Museum’s Anzani A 2 has been made whole, once again. Thanks to the incredibly talented metalworking specialists in the Preservation and Restoration Unit, the National Air and Space Museum is able to restore our collection and display these artifacts of aviation history in the most accurate and complete ways possible.

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Authors: Meghann Girard and Kenny Mills, Museum Specialists of Welding & Fabrication