Airships and the Future that Never Was

Roman Mars:
This is 99% Invisible. I’m Roman Mars.

Roman Mars:
They are hulking but graceful. Human-made whales that float in the air. For over 100 years lighter than air aircraft have fascinated us and they have this recurring starring role in our dreams of an alternate reality, of a future that might have been. Where cargo and passengers traverse the globe in a civilized fashion and dock elegantly on the mooring towers on top of art deco skyscrapers.

Roman Mars:
If you’ve seen one in real life, it was likely a blimp emblazoned with the Goodyear logo. A blimp is a non-rigid airship, meaning there’s no structure inside the balloon. It’s just a balloon. The shape is maintained by the pressure of the lifting gas inside. Then you had a little cockpit and engines and rudders on the outside of that big balloon to make it fly.

Roman Mars:
Today’s blimps are basically cute PR novelties. But for around 100 years, lighter than air aircraft were seriously proposed as the perfect design solution for all kinds of problems. Even though none of these proposals actually happened. People just couldn’t give up on the promise of airships.

Bill Hammack:
In the ’90s there was a company called Sky Station. They raised some 4.2 billion or at least solicited it to put 250 antenna-equipped airships to deliver internet service.

Roman Mars:
This is Bill Hammock. He’s the “Engineer Guy” on YouTube and an airship enthusiast.

Bill Hammack:
In the ’80s there was the British Antarctic survey. They revealed a hole in the ozone layer over the South Pole. And so pretty soon a professor suggested sending blimps that dangled electrical wires to zap ozone-eating chemicals.

Roman Mars:
Then in the ’70s, they were supposed to help developing nations.

Bill Hammack:
Using a hybrid blimp to usher those nations into the 20th century. No need for roads, no need for railroads and tunnels and bridges, but just to lift stuff in.

Roman Mars:
In the 1950s and ’60s, nuclear-powered airships with unlimited energy and an unlimited capacity for work were proposed.

Bill Hammack:
In the ’20s and ’30s they were to fulfill imperial ambitions. Both Germany and the British were looking for that, and the Americans too. They had imperial ambitions in the Philippines.

Roman Mars:
Of all those failed attempts to realize the full potential of airships, it was those imperial rigid airships heavily developed in the ’20s and ’30s that came the closest to actually changing the world.

Bill Hammack:
In an airship, you have a metal framework, and that houses gas bags that lift the ship.

Roman Mars:
Those gas bags are arranged in the metal scaffolding like peas in a pea pod.

Bill Hammack:
And then a cloth cover is stretched over that and that cloth cover is not airtight. It protects the gasbags from weather.

Roman Mars:
Underneath the fabric cover are not just gasbags.

Bill Hammack:
Because it’s not a pressure vessel, they’re able to build things inside the airship.

Roman Mars:
Like crew quarters, dining rooms, lounges, all built into the metal framework. So people move around inside the thing that you might think of as the balloon, but it’s not really a balloon.

Bill Hammack:
And that structure enables an airship to travel faster than a blimp because the force of the wind, for example, would deform the nose of a blimp and it also allows the ship to be built much, much bigger.

Roman Mars:
You’ve maybe heard the term dirigible, which is the French name for an airship, or Zeppelin, which is a German company that makes airships. Zeppelin is like the Kleenex or Band-Aid of the airship world. But the proper term, as generic and boring as it sounds, is airship.

Roman Mars:
The most promising, most opulent rigid airship of its time and I’m talking about the 1920s here, was Britain’s R101. The “R” there stands for rigid.

Roman Mars:
The rise and dramatic fall of Britain’s last great airship is the primary subject of Bill Hammock’s new book called “Fatal Flight”. Spoiler alert, when it comes to the dream of airships dominating the skies, the catastrophic and very public Hindenburg disaster may have been the final nail in the coffin.

Roman Mars:
There was the crash of R101 that built the coffin.

Roman Mars:
R101 was supposed to connect the global British Empire. It was designed to fly from London to Karachi in five days. That’s ten days faster than by sea. Taking a plane that distance took 16 days because planes had to stop so often to refuel.

Roman Mars:
Airships could also carry 30 to 40 times the cargo of airplanes. Airships just made so much sense for an empire whose reach exceeded its grasp.

Roman Mars:
So Great Britain built R101 and R100, which was its sister ship that was supposed to go to Canada and back, as the first two rigid ships in a fleet that would give the Crown dominance over the skies to match it’s centuries-long dominance of the seas.

Roman Mars:
An airship is conceptually quite simple, but it’s still an engineering marvel. It’s a gargantuan cigar-shaped math equation, balancing lift on one side of the equation and weight on the other. Minimizing the weight of the airship was always a challenge.

Bill Hammack:
There’s that rigid metal framework and that is one of the most difficult parts because that has to be lightweight, yet strong.

Roman Mars:
Yet R101 was supposed to match the sturdy luxury of a high-end ocean liner.

Bill Hammack:
I mean, I can just picture this white china that was trimmed with royal blue and silver salt shakers and crystal glasses and and small butter dishes.

Roman Mars:
But to allow for those essential refinements, everything else could only have the thinnest veneer of opulence because they needed everything to weigh as little as possible.

Bill Hammack:
One person described it, when they touch the ceiling is like a piece of stage scenery. All the walls were actually fabric. The pillars in the lounge were made from balsa covered with metal. The tables were also balsa and the chairs were made of the lightest cane. So it was really kind of an illusion, the solidity of the ship, because you just couldn’t afford to lift tons and tons of stuff.

Roman Mars:
On the other side of the equation is lift. You get lift from pumping in gas that’s lighter than air. In the case of R101, the gas they used was hydrogen.

Bill Hammack:
Well, flammable hydrogen seems like a very poor choice. It was, for a commercial airship, the only choice.

Roman Mars:
You used hydrogen instead of helium which is non-flammable because the purpose of a ship like R101 was to transport cargo. And helium is both heavier and provides less lift than hydrogen.

Bill Hammack:
What you’re interested in is the payload that you can lift. So if you subtract all of the weight that you have to lift the rigid ship, the gasbags, the water, the personnel, in a ship like R101 if you filled it with helium, you would not have enough lift to lift the ship.

Roman Mars:
The flammability of hydrogen was indeed a concern in airships, but flight engineers and crew were habituated to its dangers, much like we’re habituated to the dangers of combustion engines today.

Bill Hammack:
They felt that you just take the proper precautions. One engineer pointed out, you don’t light a match and look in your gas tank in your car. When you’re driving around with something highly flammable all of the time right now you get the proper engineering solutions and controls to do it.

Roman Mars:
The other reason why helium wasn’t an option on commercial airships was the cost.

Bill Hammack:
Helium at that time was produced in the U.S. It comes from natural gas that’s required, expensive distillation plants and most of the helium is in places like Kansas and Oklahoma and Texas. So they would have to pay for it to be imported into Britain.

Roman Mars:
Instead, you can make hydrogen onsite very cheaply.

Bill Hammack:
Almost 1/100th of the cost of helium. So that was never really an option. Never really considered.

Roman Mars:
The gasbags that contain the hydrogen are their own engineering marvel.

Bill Hammack:
It’s interesting to me as an engineer to think about the materials they had to make these gasbags because you have a problem in that hydrogen wants to permeate. It’s a small molecule and it likes to go through things. So you need something that’s very strong, that is impermeable to hydrogen or largely impermeable, and that is lightweight. And so they tried things like rubber, gelatin, glycerin, something called viscose, which is a synthetic fabric. It’s coated with latex. But they all failed one way or another. Like the viscose, if you crumpled it up, you could not uncrumple it. It would just crack.

Bill Hammack:
So they used, and this stuns me to this day, the intestines of an oxen. And specifically, the oxen intestine, it’s lined with a very fine membrane. It’s called the cecum, it’s very thin and flexible and hydrogen seeps only slowly through it.

Roman Mars:
Ox intestines are nearly the perfect material except for the size.

Bill Hammack:
That cecum of an ox is about 30 inches by 6 inches, so a little over a square foot. And yet one of those gasbags, if you laid it out, is 30,000 square feet. And so to create one of these gasbags, you would use 50,000 of these entrails or so. In fact, there was over a million and a half oxen intestines that were needed to create the 15 gas bags for R101, and it was fairly grizzly work. They delivered from slaughterhouses in Argentina, at least some of the animals, barrels of these guts. And then they would scrape them and go through this long process to prepare them and eventually to glue them together.

Roman Mars:
And to answer your question, 50,000 ox intestines, even once cured and treated to make them into gas bags, do kind of stink.

Bill Hammack:
They did. They did. Apparently, if you were up in the airship, you would smell kind of an animal smell. A musty smell also, because the cloth cover didn’t allow light in.

Roman Mars:
R101 had a few test flights in and around its hanger outside London to great fanfare. In fact, Bill Hammock surmises that the focus on PR and fanfare, rather than more rigorous and deliberative testing, led to the tragedy that was about to come on the ship’s first attempted flight to India in 1930.

Bill Hammack:
It left on October 4th about 6:30 at night, about 54 people on board. Most of them work for the Royal Air Support but some were observers and some were dignitaries. So it traveled across England and traveled across the channel into France and there were these bruising winds, and just winds so fierce that ground speed was only 30 miles per hour or so.

Bill Hammack:
And then a few minutes past two, it was about 40 miles or 64 kilometers North of Paris, and it kind of chopped through the turbulent air flying at about 1200 feet, but moving up and down a couple of hundred feet. And the top cover ripped open. The top cover was weak. It was one of the weakest parts of the ship. Then at that point, the gasbags which are made of these very thin intestines were exposed to rain. The rain pelted the gasbags. There was some decrease in lift, maybe dropped to 500 feet or so. And the control car, and no one knows why today, signaled for the engine power to be cut off. And of course it lost all dynamic lift at that point and it drove nose-first to the ground. It slid into a grove of hazel and oak trees and it burst into flame.

Roman Mars:
There’s some debate as to why it burst into flames. Bill Hammack thinks the fire might’ve been caused by calcium phosphide flares that were kept in the control car. Those ignite when water hits them.

Bill Hammack:
And of course, that ignited the hydrogen. At that point, just everything became charred. Only six people survived it. The ground was littered with these very sad everyday things. I mean suitcases, fur-lined boots, shard shaving brushes, a tin of cigarettes, I think there was a ticking watch still there, and tins of plums with its juice leaking.

Bill Hammack:
And then it was very quiet, and all you could hear was the hiss of the rain as it hit the hot metal and it evaporated.

Roman Mars:
The wreckage had barely cooled when the British government halted their airship program for good.

Bill Hammack:
It was almost immediate. R100 had flown to Montreal and back and it was in a shed and it never flew again. They eventually steamrolled R100. Sold some of the parts for scraps, sold some of it to people who wanted souvenirs.

Roman Mars:
Even though R101 was completely destroyed in the French countryside, the burned remains did float in the sky once again, at least for a little while.

Bill Hammack:
Well, the wreckage of that ship was cut up into pieces, shipped back in December to Great Britain, and it went to somebody who takes scrap metal. And then apparently, according to a newspaper account, it was sold to the Zeppelin company, and they used part of that metal to make the Hindenburg.

Roman Mars:
Because of the romanticism wrapped up in airships, their flexibility when it comes to moving huge cargo, and the fact that it requires very little infrastructure to support their operation, the hope that airships will make a return has never gone away.

Bill Hammack:
I mean, I get a question a lot. Are airships going to come back and with new materials?

Roman Mars:
Part of the reason why they don’t come back is this fiery disaster-filled legacy, which I am perpetuating right now.

Bill Hammack:
What politician wants to vote in an airship and have it crash? And somebody said, “Well, didn’t you know about the Hindenburg?” Right?

Roman Mars:
Right. (laughs)

Bill Hammack:
Now, I would note this isn’t quite fair. If you look at something like the Graf Zeppelin, which was a contemporary of R101 and a predecessor to the Hindenburg, it was in service for nine years. It crossed the Atlantic 144 times, 16,000 flight hours, 590 flights, 13,000 passengers. The first aircraft ever to exceed one million flight miles, and circumnavigated the globe in just 21 days. So there is another history back there that says that these things can be made and can be made well.

Roman Mars:
At this point, the airplane has had a century’s worth of development in efficiency, speed, and safety, so that the need for the airship has been largely eliminated, but it passed is precedent.

Roman Mars:
Some enterprising engineer is in a room full of venture capitalists right now trying to convince them that giant airships are the solution to some pressing world problem. In the meantime, the airship will continue on in science fiction stories as this quick and easy visual cue that we’re in a world that’s like ours, but somehow more wondrous.