I promised to post some more photos and a description of the bombsight vaults at Second Air Force training fields--I apologize in advance for those who are only interested in warbirds, but there are a few of us that are researching the bases and structures.
First, the description of the vaults. When the Norden bombsight came into use it was considered more secret by far than the aircraft that carried it. When the Corps of Engineers laid out a bombardment training or processing field, a vault was incorporated to store the sights when not in the aircraft, and a small workroom was incorporated as well. This smaller vault has only two rooms and has become known as a "first generation" vault. This is an entirely concrete building with safe vault doors and had electrical service to the smaller room for minor maintenance and repair. The larger room was the storage vault, and this style of building was constructed at "satellite" stations that were to have a single squadron training at a time. Here are several photos of the first generation design:
This is the front of the McCook original vault. Ivan Schmid, one of the Historical Society members, is opening the wooden door that was added several years ago to protect the steel doors. You can see the original security fence still standing in the background.
Here is a wartime photo of the Harvard AAF first generation vault complete with the same perimeter fencing. Harvard modified the roof of their vault to serve as part of the weather gathering apparatus after the larger vault was built.
This is a side view of the Bruning AAF first generation vault. The indentation shows the smaller and larger room dimensions:
At training fields that were to accomodate an entire Bombardment Group or other large number of aircraft, a much larger bombsight maintenance and storage building was required. This led to the "second generation" vault, commonly noted on 2AF Base Layout Guides as the Bombsight Maintenance Building. When a base was expanded from a satellite to a main base the larger building was constructed. These had concrete vaults with five rooms, again with steel bank vault doors. A wooden building was constructed that encompassed the vault and had a large work area for maintenance and repair. The best Midwest example of this larger building was at Great Bend AAF. When Ellen and I documented this structure back in August of 2004 it was a near time-capsule. Sadly the wooden building was torn down a couple of years ago after futile attempts to save it. The same is being done to two of the B-29 hangars as we speak.
Here is an overall shot of the two vaults together. The Engineers at Great Bend built the larger vault adjacent to the existing first generation vault that you see on the right:
Here is the interior of the maintenance room with the vaults to the left, the original coal stove and issue window at the far end on either side of Ellen. For some reason four of the five steel doors had been replaced with wooden doors after the war:
Inside four of the vaults we found the original shelving that the Norden sights were stored on! Sadly the shelves were destroyed along with the building:
This is the facility at Herington, with the first generation vault on your left and the foundation and vault for the second generation on the right:
Every 2AF Group Phase Training Base seems to have located the larger vault according to local needs. Several co-located the large vault next to the first generation structure in the center of the flightline, while the rest built the large building near the Sub-Depot hangar that was positioned at the end of the apron.
Not only were there vaults for bombsights, many fields constructed a concrete vault for the airfield lighting transformers and controls. The Finance Office had a large concrete vault, the Post Engineer and the Post Offices had a smaller one. Each Squadron Operations Building had a small vault for logbooks and other important documents, as did the Base Headquarters Building. Most of these vaults are still standing at Herington and Walker, and a number survived at McCook, Fairmont, Harvard and Bruning.
Holedigger, you're correct about an armed guard being posted at the earlier part of the war. That is obviously the reason for the fence around the early vaults. In addition, the Guardhouse was usually a stones throw from the first generation vault. The larger vaults didn't have any fence around them, and people who were stationed or worked at the bases I've been researching don't think they were too worried about the sights from late '43 on. They were still under lock-and-key, but armed guards were not deemed necessary in Kansas and Nebraska by that time.
Sorry to bore everyone,
Scott