One of the great what-ifs of history is "What if the Hindenburg hadn't burned down on live radio- making it one of the most indelible news events of the 20th century?" And what if WWII->Cold War hadn't shifted our technological priorities toward high-altitude, high-speed jet-powered aircraft- the civilian application of which is the commercial airliner. What if airships had continued to be developed? Helium, with a molecular weight of about 4 grams / mol, is twice as heavy as diatomic hydrogen (around 2 gram/mol). However, compared to air, which is about 29 grams/mol, it's still excellent. The difference between 2 and 4 grams compared to 29- about 7%. In other words, if the Hindenburg had used helium- as it was originally designed to- it would have been able to carry 7% less payload.
The real what-if actually comes earlier. What if the U.S. (the world's only supplier) hadn't banned the export of helium to Germany in the run-up to WWII? Not counting dark matter, helium accounts for 24% of our galaxy- 12x more mass than the rest of all other elements combined. Hydrogen accounts for 73.9% of what's visible. Here on earth, the only viable source for helium is as a radioactive decay product that accompanies the natural gas from certain wells in the U.S. and a- to a lesser extent- Poland.
Helium, unlike hydrogen, isn't something you'd want to throw away. The Hindenburg was designed to use dynamic envelope control which requires a heavier airframe and a higher margin of error. That's because the helium wasn't going to be vented to make for an easy decent. Switching to hydrogen allowed the Hindenburg to carry 7% more passengers and freight according to the raw numbers. It probably would have carried several percent more because of how it was being flown.
We (now) know hydrogen is dangerous. Hydrogen is actually two gases mixed together- both consisting of diatomic hydrogen- the molecules of which are arranged differently. The exact properties of hydrogen gas depends on the combination of these two isomers, which in turn, depends on how long the gas has had a chance to reach equilibrium.
In other words, fresh hydrogen is quite different from stale hydrogen.
As for safety, when it burns, it burns rapidly, invisibly (it skips the visible spectrum but is visible in IR and UV), and- provided enough oxygen- totally. It's ignition temperature (500C) is well within reach of all manner of things, including matches and static electric sparks. One of its not-quite-saving graces is that, in its pure form, it doesn't burn at all. It needs oxygen. Also, when it burns, the flames tend to rise quickly and it produces no smoke. Most of the people who died on the Hindenburg died because they were inside the hull and had nowhere to escape to as the ship's diesel burned nearby. Out of 97 passengers and crew, 61 survived.
Helium is relatively safe. Its stable, non-reactive, and fun. The only way it can kill you is by asphyxiation- since breathing pure helium has all the health benefits of not breathing anything at all. Mix it with the right amount of oxygen, however, and you've got a superior diving gas.
Helium, if made available at the right moment, would have harnessed innovative energy that was dedicated to high speed aircraft. That shouldn't sound like a total shame. Jets are fast. And not too expensive. And safe. But they're also the only option. And they're expensive. Take a 15 hour trans-oceanic flight without enough room to unfold your knees. And then consider the following:
According to estimates, there were over 4 trillion ton-miles of intermodal domestic freight shipped in the United States during 2008. Intermodal means "by every method." The worldwide volume of freight transported by sea is over 35 trillion ton-miles. This represents 4x increase over the last four decades. And all of it, ALL OF IT, is powered by fossil fuels. In fact, around *half* of that freight volume IS fossil fuels: crude, oil products, and coal being freighted from one part of the world to another.
The most efficient mode of transport is using very large ships (boats). Boats are incredibly efficient when compared to rail, road, and runway. Boats are made of steel, which is cheap and abundant. Large ships involve a lot of surface area, and hence, a lot of friction with the water they travel through. But they also have enormous amounts of internal volume. And the bigger they are, the more favorable the ratio between area and volume. And they don't go very fast, so induced drag isn't too bad. Only problem. Boats don't work on land.
Next most efficient is rail. Low speed hence low friction. Low manpower costs. Efficient engines. Logistics are slow and, for many products, unworkable. To really do point-to-point transport, you need trucks. High manpower costs- which mitigates the highly fluid logistical challenges. Not extremely efficient, but enormously flexible. And both rail and trucking require infrastructure that needs to be maintained. And we won't discuss airfreight, which has only speed to its advantage, which solves a lot of logistical issues in one fell swoop. Remember when the idea for FedEx got a C when it was turned in as an assignment at Harvard Business School?
So here's the question we're drifting toward: could airships have had a role in transporting freight? The short answer should be obvious: no. They don't so they couldn't. There are only around 50 working airships- most of them blimps- and precious few of them are used for transporting anything resembling freight in any meaningful way. The golden age of airships ended with the burning of the Hindenburg- just as it was getting off the ground. But the reality is, airships were on their way out anyway. The Hindenburg wasn't the first airship to go down. The U.S.S. Macon, which was nearly as large- and which was filled with helium- experienced a far more dramatic trip to earth (unless dramatic = flames, in which Hindenburg wins most competitions). Hindenburg was just the most visible. Also, at the time, airships were competing, not with air travel, but with sea travel. Considering the risk of being sunk by a submarine, the definition of "safe" was a rather low mark. And the Hindenburg would have made for an extremely poor flying truck. It's crew consisted of more than forty people. It was a niche craft.
It may have been beautiful, immensely romantic, and intensely inspiring to look upon. But inspiring doesn't pay bills. And inspiration that doesn't reproduced isn't worth much.
Here's the crazy thing, though. The design for airships like the Hindenburg- that distinctive torpedo-like shape- actually pre-date the invention of the airplane by a about twenty years. Count Ferdinand von Zeppelin was making flying cigars in 1894. And there were elongated dirigibles that date back to the 1880s. By the time Orville and Wilbur started toying around with powered kites, Zeppelins were a major industry. And everyone knows that airplanes win wars while airships much prefer peace. (German Zepellins were used to bomb London during WWI but after 1915- during which they lost at least half their airships, they abandoned their use. One of them was bombed out of the air by a British pilot flying an early monoplane. Live by the bomb, die by the bomb.
So here's another big "what if?" What would have happened if airships and airplanes had been developed at the same time?
What would have happened if the following ingredients were combined in a single place?
1. Helium made available as an openly-traded commodity.
2. Aerodynamic lift theory applied to lighter-than-air craft.
3. Application of progressive materials science coupled with advanced structural engineering.
4. No intrinsic fear of airships among the general public.
I'll tell you what *might* have happened.
Airships might have matured into lifting body hybrids. Flying cruise ships. Flying trucks- able to sail on prevailing winds. Flying construction cranes. Maybe even flying towns. Flying launch platforms.
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