Researching the commercial structure on Eleventh Avenue and West 46th Street now named Metropolitan Lumber, I came across a gigantic cylindrical structure looming over that same entire block on 1940 tax photos. Checking the map it became obvious that it must have been a gas holder of the Consolidated Gas Company of New York.
History
Digging a bit deeper, I learned this gas holder replaced a number of smaller ones one block further south. In 1940, as we see it on several tax photos from that year, this large gasometer was fairly new. Its unusual appearance is based on a type of gas holder developed by the German manufacturer M.A.N. developed in the 1920ies. The earliest photo I could find showing the new gas holder is from December 1927. With an estimated height of more than 200 feet it must have been a constant presence in the neighborhood. The neighboring block south of West 45th Street also included buildings from that same company, most likely used for the local manufacturing of coal gas.
It’s not clear to me if town gas was still manufactured in 1940 on place or if the gasometer was just used for storage and maintaining the necessary pressure of gas manufactured elsewhere in the city. Most likely, the days of that relatively new gas holder were numbered anyway. By the 1950ies the conversion from coal to natural gas in the US was already progressing. We can assume that there was no more use for the gas holder twenty years later. It had disappeared from the corresponding tax photos from 1980.
In any case, I decided it could be an interesting project and I’d consider it for my 1950ies timed layout. Not only it would look great but it could also add operational interest if I assumed for the purpose of my layout that a nearby facility manufactures the gas. Some close-ups of a MAN type gasometer helped me also better understand how it was designed and what would create that unusual surface with the horizontal linear texture.
Selective Compression and Design
Unlike the more traditional column-supported gas holders, the MAN type is a static, self-supporting structure. It has no movable parts visible from the outside. The movable cover that rises and lowers with the amount of gas stored is inside the cylinder and not visible. This makes is easier to build as a model as it is basically just a static cylinder.
The structure has an (equilateral) polygonal base with 22 or 24 corners. Horizontally, it is structured into a stack of cylindrical segments (between five to seven), each one built with as many (vertical) plate girders as there are corners. Each plate girder has longitudinal stiffeners, in the case of the W45th Street gasometer eighteen. Each segment has a circular walkway that goes around the entire gas holder. Additionally, the structure has a vertical elevator shaft from bottom to top and a staircase connecting the walkways of the various levels. The top of the gas holder includes walkways, an access door to a dome-like central structure, as well as other rooftop installations like vents and skylights.
The full estimated size of the structure of 180 by 230 feet (the typical MAN type gasometer has a 70 meter elevation) would translate into a giant 13″ by 17″ cylinder in N scale. That’s beyond the real estate I can and want to provide on my layout for a single industrial structure. I figured out that a 4″ diameter would be big enough to make a good impression. For the elevation I settled on three stacks plus a cover on top of a smaller segment. This would give me a height of 7.5″. That’s a compression factor of more than 2 for both dimensions. I also decided to make the polygon with 16 corners or sides, much less than the prototype.
Construction
Once I understood the design, I mapped out the parts required for the hull in a hierarchy. Starting with the design of a single vertical girder, I’d be able to build a 90/4 or 22.5 degree sector. To get the proper curvature of the surface, I’d combine 4 out of the 16 girders for a full circle into one 90 degree sector. Ten horizontal stringers define the shape of the sector and are its starting point. The 90 degree sector is the basic building block for my design.
On the inside, the four separate web plates are glued onto the stringers. Gaps cut into the web plates and tabs on the inside of the stringers ensure a perfect fit. With the web plates glued into place, I then could insert the vertical flanges of the web plates from the outside. To complete the raw 90 degree sector, I’d add a cover that emulates flange plates of the stiffeners on the outside as well as their gusset plates. Again, interlocking horizontal tabs in the stiffeners and tabs in the vertical flanges inserted into gaps in the cover ensure a perfect fit (this one has a tolerance of less than a 0.1 mm).
In total, a sector required 10+4+4+1 or 19 parts (leftmost photo below). I used .015″ laser board for all parts. The assembly consisting of these 19 parts is stiff and strong, just as its prototypical counterpart. Priming the stiffeners and web plates before adding the cover for the web flanges makes the assembled structure even more robust.
Assembly
To facilitate the gluing of the web plates onto the ten stiffeners, I first created a jig (center photo above). This made the construction of a four-girder sector very efficient and helped with scaling up the construction. Four of these would then give me one segment of 2″ height (or about 27 scale feet). For the entire hull, I needed 3×4 = 12 such sectors. Once I had built an entire one-story segment of four sectors, I realized that by shifting the cover by 45 degrees, I’d get a more perfect cylinder (rightmost photo above). The shifted layers also result in a much stronger segment. I also added a fitting ring made of 1/16″ MDF at the bottom. This would give me a flange that also facilitates connecting two segments.
A circular walkway tops each segment. I constructed it from one circular ring, adding railings at the outside and brackets on the underside, all made from .015″ laser board (leftmost photo below). I gave it a metallic surface by applying Vallejo aluminum spray paint. The handrails have a diameter of less than .020″ but the paint renders them elastic. I delayed gluing the walkways to their segments until the very end, avoiding to much stress on those delicate parts.
Building the Cover and Adding an Elevator
Designing and building the roof of the gasometer was a bit more complicated. According to other photos of MAN-type gas holders, the roof has a spherical shape with a cylindrical structure at the center which provides access to the space between the roof and the top of the gas storage. Again, I had to use a modeler’s license to get a shape that meets these basic criteria. I first built a hub-and-spoke skeleton structure with 1/8″ and 3/32″ basswood, then covered it with laser board. The roof walkways are entirely on the roof and don’t need brackets. I used a similar design to the circular walkways on top of the segments.
The last challenge was the elevator shaft. I designed it such that I could hook it into the flanges of the horizontal stiffeners. But that meant that I had to build it in segments with a flexible height. To achieve this, I built the three plus one segments in two layers so that the segment on top could telescope into the lower one. To keep the segments straight in line, I built them around a 10 mm wide square basswood dowel. I engraved the outer layer as corrugated sheet even though I could not find evidence of that material.
To finish it, I primed and painted the elevator shaft in a beige-gray color and weathered it with red oxide powdered pastels. The same way I also weathered the gas holder’s roof.
Model and Prototype
Looking at the finished product, I’m aware that the model differs significantly from the real object. The translation of the original plate girder design into N scale requires an adjustment of the proportions, at least when using precision-cut sheet material. For me, building this model was more an educational process than a prototypical reconstruction of a MAN-type gas holder. My next version of the West 45th Street gas holder I will most likely build with the help of more prototypical 3-D printed plate girders. Nevertheless, I like my gasometer and it was definitely fun to build.