LZ 130 Graf Zeppelin

The Graf Zeppelin II was virtually identical to the Hindenburg, and was originally designed to use hydrogen as lifting gas. The LZ 130 was built to replace the aging LZ 127 Graf Zeppelin on the South American transatlantic route while the Hindenburg would continue flying the North American route. Following the Hindenburg disaster in May 1937, Dr Hugo Eckener vowed never again to use hydrogen in a passenger airship. This led to modifications so that the Graf Zeppelin II could be inflated with helium. The only source of helium in large enough quantities at that time was the United States, so Eckener traveled to Washington, D.C. to lobby for helium for his airships. He visited President Franklin D. Roosevelt, who promised to supply helium, but only for peaceful purposes. After the German annexation of Austria in March 1938, U.S. Secretary of the Interior Harold Ickes refused to supply helium, and the Graf Zeppelin II was ultimately inflated with hydrogen. Though the LZ 130 was nearly identical in design to the LZ 129, there were a few minor improvements. The tail fins were shorter and the number of intermediate ribs was reduced to save weight and reduce stress on the trailing edge of the fin. As the ship was designed for hydrogen, there would be additional "luxury cabins" with windows on the starboard side allowing for a total of 70 passengers (this was added to the Hindenburg over the winter of 1936–1937). The lower fin had an upward curve similar to the Hindenburgs final configuration (repairs made after a tailstrike incident during the propaganda flight on March 26, 1936), giving more ground clearance. To further reduce weight, the girder shape and riveting were changed slightly. The four engine cars were initially designed and installed to have the same pusher configuration as the Hindenburg; after the Hindenburg disaster, they were completely redesigned, using the same DB-602 diesel engines powering tractor propellers. The new gondolas were slightly larger to accommodate the new exhaust water recovery system and were better insulated than those on the Hindenburg, with engine noise noticeably reduced. The water recovery system condensed the water vapor in the engine exhaust and stored them which compensated for the weight of fuel consumed during flight and eliminated the need to vent any lifting gas. In later flights, the airship used variable-pitch three-bladed propellers on both rear engines; trials were run on the forward port engine car as the ship neared completion, but only the aft-port engine car had a three-bladed propeller on its first flight. Unlike the wooden propellers of the Hindenburg, which had problems with moisture absorption causing imbalance, these three-bladed propellers were made of plastic wood and individual blades were assembled onto a main hub. The 16 gas cells were lightened and one was made of lightweight silk instead of cotton. On the bow near the nose cone there were just two windows, as in the Hindenburg's original design (in the Hindenburg, more windows were later fitted after its test flights.). The German investigation on the Hindenburg disaster suggested the poor conductivity of the Hindenburgs outer skin played a role in the ignition of hydrogen. As a result, the cords connecting the panels were treated with graphite to increase the outer covering's electrical conductivity. Other redesigns included the gas vent hoods, gondola windows and the landing wheel design. The interior of the Graf Zeppelin II was markedly different from the Hindenburg; the passenger decks were completely redesigned to accommodate 40 passengers, compared to the ''Hindenburg's 72. Viewed externally, the promenade windows were half a longitudinal panel lower compared to the Hindenburg. The twenty cabins were more spacious and had better lighting compared to those of the Hindenburg; thirteen of them had windows, and four of them were "luxury cabins" on the upper "B" deck. Instead of two passenger decks, the Graf Zeppelin II'' had one and a half, divided into four sections. The "A" deck consisted of the dining room along the central rear section of the passenger quarters, slightly elevated from the "B" deck running along the upper promenade windows, which contained lounges, smoking room and the luxury cabins. Sixteen passenger cabins as well as the galley and passenger lavatories were located in Deck "C". Deck "D", at the rear of the lower deck, contained the officer's mess, crew's mess and lavatories, as well as the radio and electrical rooms. Construction timeline 23 June 1936 – The keel of the airship was laid and the main rings were fastened onto the roof of the hangar. Although the first few rings were assembled within the hangar, a separate ring assembly shed was completed soon after, and rings were constructed and transported from the shed to the hangar using tracks on the field. 14 February 1937 – The nose cone was installed. In the same month, the fabric was also applied over the framework. 6 May 1937 – The LZ 129 Hindenburg bursts into flames and crashes while landing at Lakehurst, New Jersey, killing 35 out of 97 people on board and one member of the US Navy ground crew. Although the LZ 130 had intended to be launched later in the year with a passenger flight route to Rio de Janeiro on 27 October, the plan was cancelled after the loss of the Hindenburg and prompted several alterations of the LZ 130, such that its construction would be further delayed. November 1937 – Chief designer Ludwig Dürr proposes a redesign of the engine car gondolas to tractor configuration for better efficiency, so that both sides of the gondola can act as radiators. Wind tunnel tests in October showed a significant decline in propeller performance of the original engine cars with the water recovery system taken into account. 15 August 1938 – Inflation began on gas cells. 20 August 1938 – Engines and electrical connections are tested. 22 August 1938 – The radio communication system is tested. 14 September 1938 – The ship was christened and flew the first time. Only Zeppelin Company officials and Hermann Göring were present; no other government representatives came to the christening to congratulate Eckener, and he made the speech himself. Although a banner with the name Graf Zeppelin 2 (with Arabic numeral) was hung on the wall of the construction shed during the airship's assembly, the LZ 130 itself never bore an additional numeral, since the original Graf Zeppelin (LZ 127) had been retired. By the time the Graf Zeppelin was completed, it was obvious that the ship would never serve its intended purpose as a passenger liner; the lack of a supply of helium was one cause. The Reich Air Ministry permitted the Graf Zeppelin to fly "for one year until 1 September 1939 without any transportation of passengers and outside of tropical areas". Dr Ernst Breuning, who was responsible for radio development for the RLM, negotiated with the Zeppelin company to have the airship used as a laboratory for radio surveillance and measurements. As a result, the passenger accommodations were modified to contain radio and measuring instruments. Part of the cover was to have the airship make public appearances at air shows ("Flying Days") and deliver mail. In addition to Breuning's group of radio engineers (termed "Group R") who boarded posing as civilian passengers, there were also a team of physicists from the Drahtlostelegraphische und Luftelektrische Versuchsstation Gräfelfing (DVG) led by Max Dieckmann, whose intention was to study meteorological conditions and the role of electrostatic discharge in the Hindenburg disaster. ==Operational history==