Small Test Stand D-4
Building number 620c

This test stand was built in 1953. It was 14' square, of heavy reinforced concrete, with large double doors which were opened for horizontal firings out the south side. Engine mounts were attached to steel rails in the floor during testing. Apparently firings in D-4 were controlled and monitored from the Central Control Room (Building 3607) for the first few years. Then in 1956 a new control room (Building 3605) and test stand (Building 3606, Test Stand D-6) were built immediately to the east, forming a 3-building unit. In 1958, plans were drawn up to convert both D-4 and the adjacent large vertical test stand (D-1) to specialized stands for testing liquid-propellant engines. The conversion of D-1 was never carried out, but D-4 was altered substantially. An 18' reinforced concrete addition was built on the north side, comprising two main sections. One large section (14' x 14') was divided into two rooms with a north-south wall separating them. The west bay was for fuel tanks, the east for oxidizer tanks. New wall pockets were cut into the concrete wall between the test bay and the tank rooms. Two smaller valve rooms (each 4' deep) were located on the north side of the tank bays, with exterior doors at the sides, and there was a 5'-deep rectangular concrete-block neutralization pit, with a steel cover, adjacent to the north exterior, to provide access to piping. Tanks were pressurized with Nitrogen that was piped throughout Test Area D. According to a circa 1959 description of Test Stand D-4, it could be used for testing engines with up to 30,000 pounds of thrust.

Building Information

Year Built



Reinforced concrete


1 story, 32' x 14'


Northern 14’x18’ section with tank and valve rooms added 1958

Additional Building Photographs

  • Building No. 3603Building No. 3604
  • Building No. 3604Building No. 3604

Drawings (click on the image for a separate close-up view)

  • Building 3604 framing plan
  • Building 3604 heating and plumbing plan
  • Building 3604 Section Plan
  • Building 3604 electrical plan