The D class blimp was a patrol airship used by the US Navy in the early 1920s. The D-type blimps were slightly larger than the C-type and had many detail improvements. The Navy continued the practice of dividing the envelope production between Goodyear and Goodrich. The control cars were manufactured by the Naval Aircraft Factory. The major improvements over the C-type blimps were a better control car design and easier, more reliable controls and instrumentation. The engines were moved to the rear to reduce noise and allow better communications between crew members. The fuel tanks were suspended from the sides of the envelope. The envelope was identical to the C-type, except an additional six-foot panel was inserted for a total length of 198 feet (60 m) and a volume of 190,000 cubic feet (