The Cruciform Tail Structure

LIII

Goodyear-Zeppelin of Dayton, Ohio was building the world's two largest helium airships for the United States Navy in 1929. The U.S.S. Akron (ZRS-4) and the U.S.S. Macon (ZRS-5) were both designed by a protege of Graf von Zeppelin's, the aeronautical engineer, Dr. Karl Arnstein. They incorporated revolutionary new framing designs and ballast water retrieval systems. They were designed to be flying aircraft carriers, and were the world's two largest airships when they were launched.

1929 was also the year that Goodyear-Zeppelin partnered with DELAG to build the world's largest civilian airships. There were to be four, designated LZ-129, LZ-130, LZ-131 and LZ-132, and they would represent two different "classes" of airships.

DELAG ordered up the Duralumin for the frame and the gel rubber gas cells of LZ-129 in October 1929, but they were slow in arriving. The Great Depression, which began that month, slowed all business to a glacial crawl and Goodyear-Zeppelin essentially bowed out of the project. The first Duralumin was not delivered to DELAG until 1931, and construction did not begin, even fitfully, until 1932.

DELAG chose to make use of the Goodyear-Zeppelin designs so that outwardly, the LZ-129 and LZ-130 would look much like the Akron and the Macon.

The internal structure of DELAG airships LZ-129 and LZ-130

Akron and Macon each carried a crew of about 75, and had a top speed of 80 miles per hour. LZ-129 and LZ-130 both would fly at a top speed of 85 miles per hour. Each would carry fifty crew and 70 passengers.

The Akron and the Macon were both 785 feet long. The LZ-129 would be 804 feet long, and the LZ-130 (oddly) only 803.5 feet long. LZ-129 would be only eighteen feet longer than the Akron and Macon and just 79 feet shorter than the Titanic, in fact.

The Akron and the Macon would be 133 feet in hull diameter. The LZ-129 and LZ-130 would be 135 feet in diameter.

The internal structure of the Goodyear-Zeppelin airships U.S.S. Akron (ZRS-4) and U.S.S. Macon (ZRS-5). Note the external ring attachment of the stabilizers (top left).

The Akron and the Macon both carried 7,401,260 cubic feet of helium. The LZ-129 and LZ-130 would carry 7,062,000 cubic feet of hydrogen. The Akron and the Macon had a lift of 400,000 pounds; the LZ-129 and LZ-130 had a lift of 512,000 pounds, hydrogen being lighter than helium.

All the new DELAG ships were configured either for hydrogen or for helium, as Goodyear-Zeppelin had access to the more expensive but safer gas.

The cruciform tail structure of German airships meant that all four stabilizers were joined at a central point at the center of the hull adding strength to the ship

Dr. Eckener did not think much of Dr. Arnstein's framing designs or of the water condensers built into the ships' hulls, preferring to retain the water catchment system used on the Graf Zeppelin. He also retained the traditional compasslike cruciform tail structure, which, he felt, added strength to the ship (and was proven correct when both Akron and Macon were lost in accidents caused partly by structural failures).

The loss of the U.S.S. Akron in 1931 was the worst airship disaster in history, claiming 74 of the 76 lives aboard.

The U.S.S. Akron suffered a series of structural failures, including torquing and the loss of a stabilizer. She hit the ocean surface during a violent storm. Most of her crew was killed