THE DELETERIOUS EFFECTS OF PASSING GAS

One of the major by-products of the internal-combustion engine is water vapor. In the 1930s, German aeronautical engineers devised a scheme to collect, condense, and retain the water from the engine. Further, they strove to have collected at any given moment the exact same weight of water equivalent to the weight of the fuel burned.

Can you figure out why they would want to do this? The answer is below. You just have to scroll through the picture of the cats to get to it.

The answer is, of course, for use in dirigibles. The dirigible was a rigid bag of lighter-than-air gas (the Germans used highly-inflammable hydrogen) holding suspended below it a passenger gondola and an engine (or engines) with propellers to shove the whole thing forward. If the weight of the fuel burned by the engines was not replaced, the whole contraption would eventually get lighter and fly too high. It was much easier, safer, and less expensive to compensate for the lost weight of the fuel with an equivalent amount of water rather than trying the alternative of bleeding off hydrogen--especially since there would often be the risk of sparks from static electricity present.

The below photo of the dirigible Hindenburg illustrates why one would want to avoid as much as possible messing with the hydrogen and static electricity. The Hindenburg, by the way, did not have a water-recovery system and had to rely upon dropping water ballast that had been loaded prior to flight. It also purged 1 million to 1.5 million cubic feet (28 million to 42.5 million liters) of hydrogen gas per each flight across the Atlantic.

If you wished to see how long it takes to disable by fire a dirigible filled with hydrogen, click here.