ONE OF THE ENGINE GONDOLAS, of which there are four. Each gondola carries a water recovery system by which eighty per cent of the weight of the fuel used can be regained. The engines are Mercedes-Benz of 1,200 horsepower each and drive three-bladed tractor propellers. The cruising speed of the airship is eighty miles an hour.
THE new airship LZ 130, and now named Graf Zeppelin, is Germany’s 119th Zeppelin, eleven designs not having been put into construction. Similar in general design to the Hindenburg, the new Graf Zeppelin has an overall length of 804 feet and a maximum diameter of 135 feet. The length-to-breadth ratio is approximately 6 to 1. The airship’s gas capacity is 7,060,000 cubic feet and her greatest height over landing wheels is 146 feet. She is built on the well-proved rigid method (see the chapter “Types of Airship”), and the lifting gas is contained in sixteen independent gasbags.
This airship was originally designed for inflation with hydrogen gas and was almost completed when the Hindenburg was lost through the ignition of that inflammable gas. The German Air Ministry then ordered that all future airships should be inflated with a non-inflammable gas. This meant that the constructors of the LZ 130 were immediately faced with more than one problem if the ship were to carry a real payload across the Atlantic.
So far, the only known non-inflammable gas suitable for airship operation is helium, but this has the drawback of one-seventh the lifting power of hydrogen for the same capacity and costs ten times as much. Therefore the first two obstacles to be overcome with the new LZ 130 were a saving in weight without a loss in structural strength, and a reduction in operating costs.
The weight problem has been tackled so successfully that it has been possible to reduce the structural weight of the ship by twenty tons. Part of this reduction has been achieved by redesigning the passenger accommodation.
In the Hindenburg the accommodation was contained on two decks; in the new Graf Zeppelin this is built principally on the upper deck, or “A” Deck.
Twenty two-berths staterooms, with hot and cold running water, hanging wardrobes and so forth, are situated on the fore part of the starboard side and towards the centre of the hull.
Abaft the staterooms and athwart the centre of “A” Deck is a well-appointed dining-room, with tables and seating accommodation for forty people.
On the lower deck, or “B” Deck, are the officer’s mess room, electric kitchen, bathroom and lavatories. Both decks are fitted with large observation windows.
The airship, operating in the worst conditions of weather and temperature, will thus be able to carry forty passengers, a crew of thirty-eight, ten stewards, ninety hours’ fuel, and from five to six tons of mail and freight. The Hindenburg, inflated with hydrogen, carried fifty passengers and ten tons of mail and freight.
An airship after several hours or, in a transatlantic crossing, after two or three days’ flying consumes a certain amount of fuel, and before landing would have to valve an amount of gas equal in volume to the weight of the fuel consumed to reduce the quantity of gas to be released. British airship officers produced the first water recovery system in 1911 (see the chapter “Construction of Rigid Airships”), and this has from time to time been improved upon.
When the Hindenburg was lost the water recovery system was still a long way from perfection. If the operating costs of the helium-inflated Graf Zeppelin were to be reduced, the amount of the much more expensive gas to be valved during flight had to be reduced to a minimum. This could be done by a combination of two things: placing electric heaters in the gasbags, and a considerable improvement in the water recovery system.
By heating the gas 3° Centigrade over the existing atmospheric temperature, then allowing it to cool as the ship leaves the ground, she attains the required flying height without loss of volume. Further experiment has produced a water recovery system which gives a gain in weight of 80 per cent of the fuel consumed. This has been installed in the engine gondolas of the Graf Zeppelin.