Modeling the Southern Pacific A-50-17 Part I

Modeling the SP in late 1951 means I would like to have models of the following auto (double door) cars on the roster:

Class (HO scale model)

• A-50-4 (Speedwitch)
• A-50-5/6 (Funaro & Camerlengo)
• A-50-7 (no kit; radial roof version of A-50-6)
• A-50-9/10/11 (Speedwitch kit coming for A-50-11)
• A-50-12 (Sunshine)
• A-50-13 (Sunshine)
• A-50-14 (Proto 2000 redetail [not really a full-blown kitbash])
• A-50-15 (kitbash of Branchline)
• A-50-16 (Sunshine)
• A-50-17 (Branchline kitbash)

Prototype photo of SP 192866. Note the panels called out as having rectangular corrugations. Fayetteville, North Carolina, July 14, 1952, Col. Chet McCoid photo, Bob's Photo

The last class on this list is the subject of this post, Part I of what will be several. The A-50-17 class was built in 1950-1951, car nos. 190000-190499 and 192000-192999. All cars in the 190000-series were equipped with Evans Type F automobile loading racks (a note in SP Freight Cars, Volume 3 from Signature Press indicates that 100 cars mixed in the 192000-series also had auto racks, although the October, 1951 Official Railway Equipment Register does not yet show any cars in the 192000-series with racks.) Interestingly, cars in series 192000-192499 are classified XM "Box, All Steel" while cars in 192500-192999 are classified as XM "Auto, All Steel". The difference is not clear (if there is any difference) and no special loading equipment is noted in the ORER. 

While Branchline made a rather nice kit for late 1940s and 1950s 50' auto cars, the SP's A-50-17 incorporated details not covered by the Branchline models. There are two notable differences. The A-50-17 had sides that used "hat-section" structural members, necessitating two rows of rivets (one alternating) where the side sheets overlapped. Additionally, the A-50-17 had four steel sheathing "panels" to the left of the doors and six to the right, fewer than the five and eight of the Branchline models. This will be addressed and described in a separate post.

The other significant difference is that the roof employed was a hybrid of diagonal and rectangular panels. By the time these cars were constructed in late 1950 and early 1951, diagonal panel roof corrugations had superseded rectangular corrugations. However, in this instance, two panels near each end of the car used rectangular corrugations to accommodate automobile loading racks on cars so equipped (all cars had the "hybrid" roofs, regardless of whether equipped with racks). 

To replicate this unusual roof, I decided to marry pieces from a Branchline 50' diagonal panel roof and a Branchline 40' rectangular panel roof. The edges of the underside of the center portions of Branchline roofs do not have any "depth" like the ends do.  If not filled, this lack of depth would adversely affect the cuts with the razor saw, as well as efforts to square the cuts with a Northwest Shortline True Sander. I added strip styrene to fill in these areas (0.040" x 0.040" on the rectangular panel roof and 0.030" x 0.040" on the diagonal panel roof - white strips in the photo below). After sawing, the pieces were spliced together as shown here. I used a razor saw and mitre box to make the cuts, leaving excess material to be sanded using a Northwest Shortline True Sander. My goal was to reassemble the pieces using the "center" of the roof seam caps as the mating line, creating relatively easy joints to sand clean (the photo shown here is prior to sanding the seam caps.) 

Once I had the pieces glued together, but while the joints were still "soft" from the MEK, I placed the roof into the car body, with light pressure applied with rubber bands. This ensured that the parts would be in fairly good alignment and flat as the joints dried and hardened.

I am pleased with the results. I will have copies made for offer at some future time (along with decals for the A-50-12 through A-50-17 classes of SP auto cars).

Know of another prototype that used this roof? Please leave a comment below...