 This model shows the largest airship of its time and perhaps the grandest, the most luxurious craft ever to fly. This is the British airship R101, built between 1924 and 1930. It was Britain's answer to Germany's Zeppelin. To give you an idea of its size, compare it to this 747, one of the largest planes flying today. This miniature jet is the same scale as the airship model, but the airship is over 500 feet longer. You know, the engineering of this airship fascinates me so much that I wrote a book telling its story. So in this video, I'll draw on the research for that book and use some of the old magazine articles, newspaper clippings, and photos that I've gathered over the last decade to reveal the design choices of the ship's engineers, the daily life of a crew member, and the opulence of the passenger areas. But first, let's look at the grand plan for this airship. It was to fly a regular route from England to India, connecting the countries in five days, ten days faster than by sea. The airship's air rival, the plane, linked London to Karachi, then in India, in 16 days, but with frequent stops to refuel. This airship was one of two built by Britain about a decade after the end of the war when they embarked on an ambitious airship building program. They constructed the airship R101, but also R100, the stands for rigid, which were to carry 50 passengers at a cost close to that of first class in an ocean liner. One proponent estimated a ticket from Australia to the United Kingdom would cost ten pounds. The British spent over two million pounds in the 1920s to create commercial airships. Their competitor was Germany's Graf Zeppelin. It was 40 feet longer, but R101 had a larger cross section and so held 30% more hydrogen and carried more passengers. To put these ships in perspective, here's the Hindenburg, built about seven years after R101. The British intended R101 and its sibling ship to be the first of a fleet. Ultimately, the British envisioned an old red girdle of air transport that reached more than halfway around the globe. Red was the striking color of empire territories on official maps. Now, this map illustrates that vision. At the bottom, in the legend it reads, possible imperial airship routes. The British envisioned using airships to link the far flung corners of their colossal empire. It covered a quarter of the world and encompassed a fifth of its population. R101 promised British dominance of the air to rule the skies as British dreadnoughts ruled the seas. They planned an infrastructure of towers centered on the Royal Airship Works, west to Canada, Halifax, Ottawa and Quebec, and then south to Cairo, Karachi, the time in India, Cape Town, Mumbasa and Melbourne in Australia. This vision might seem grand to us today because we often think of lighter-than-air craft as a novelty, a hot-air balloon or the blimps used to cover the Super Bowl, but these are mere shadows of the greatest of all lighter-than-air craft. The Airship Unlike an airship, balloons and blimps are both pressure vessels. Their shape is maintained by the pressure of the lifting gas. In contrast, in an airship like R101, its shape is formed by a metal framework. The metal skeleton houses the hydrogen-filled balloons, called gas bags, that lift the ship. These bags are protected by a cloth cover stretched across the framework. The cloth cover is not, of course, gas-tight. Its purpose instead is to keep wind, rain and sun from damaging the gas bags. This structure enables an airship to travel faster and have a much larger payload than a blimp or balloon. To construct such a craft required clever engineering in the 1930s and era before plastics. This is best reflected in the ship's 15 giant gas bags that held over 5 million cubic feet of hydrogen, enough to lift about 170 tons. To construct these gas bags, the engineering staff searched for a material that was impermeable to hydrogen, a small molecule that is notoriously difficult to contain. Yet they also needed a material that was lightweight, flexible, yet durable. They investigated rubber and viscose, an early synthetic fabric coated with latex, but when crumpled and inflated, each of these materials cracked and leaked. So they settled for the traditional material used to construct airship gas bags, oxen, more specifically part of the intestine of an ox. The outside of an ox's intestine is lined with a fine membrane called the cecum, which is thin and flexible and through which hydrogen seeps only slowly. The grisly work of fabricating the gas bags was done by the women of the Royal Airship Works. In a room reeking of rotting meat, they soaked in testines, scraped away lumps of fat with blunt knives, soaked the skins overnight, and then scraped again, and then glued the pieces into larger and larger sheets, no stitching unlike for zeppelins, until they had enough to wrap around an air-filled form to construct a gas bag. To appreciate the magnitude of their task, consider how many entrails were needed to make a bag. The cecum of an ox is about 30 inches by 6 inches, a little over a square foot. Yet one of our 101's gas bags, when spread flat, covers 30,000 square feet, a square about 175 feet on a side. So inside that yellow circle, the tiny dash, is a single cecum. So in total, they glued together for a typical gas bag, some 50 or 60,000 entrails, to create a double walled gas bag that held 37,500 cubic feet of hydrogen, yet weighed a mere 30 pounds. Flammable hydrogen to fill these bags seems a poor choice for an airship compared to inert helium. In principle, helium lists 93% of the weight hefted by hydrogen. You would think that lift would drop by only 7%, which would be a small cost to pay for safety. Yet for a commercial airship, hydrogen is the only choice. It allows a lighter and thus less expensive airship to be built. Here's why. Let's look at the lift of our 101 with both hydrogen and helium. A ship like our 101 carries about 5 million cubic feet of lifting gas, that's a gross lift of a bit over 177 tons for hydrogen, and for helium, about 93% of that lift, or about 165 tons. But that's for pure hydrogen and pure helium. In practice, the purity is less than 100%, especially for helium, and so you lose several tons, which means helium lifts only about 88% of the amount lifted by hydrogen. Now, let's calculate the amount of payload available. The airship's framework weighs about 113 tons. Next, the essential fuel in so-on needed to operate the airship take up another 44 tons. So in the case of hydrogen, that leaves 13 tons of payload, lift for passengers, fuel, freight, and so on. The stuff that makes an airship commercial, well, for helium, that net payload is an astonishing minus 7 tons. That is, the airship could not lift a payload. In fact, in this example, which is typical, they could not even lift the crew and fuel. In addition, helium was tremendously expensive, some 70 times the cost of hydrogen. Typically, helium was captured at gas wells in the United States and shipped to the United Kingdom while hydrogen was produced on site from steam. The Royal Airship Works used the lane process, in which steam was reduced to hydrogen by passing it over metallic iron at a high temperature. Once lifted by the hydrogen, the airship flew at an altitude of about 2,000 feet and at a maximum of about 60 miles per hour. The ship was powered by five heavy oil engines housed in cars underneath the airship, two in the front, two near the middle, and one near the tail. Each engine was attended by an engineer, and the rear engine car was Joe Binks. He's on the right here, dressed in his flying suit. For eight hours at a time, Binks kept the engines in repair as he waited for orders from the control car. The orders were communicated via dial labeled standby, slow, half-throttle, or full-throttle. A rotating pointer indicated the proper action. The pointer's rotation was punctuated by a bell. Binks worked under harsh conditions. This illustration from a popular magazine makes it seem roomy, but in reality he couldn't stand at full height. This photo of the car being built makes clear how little room Binks had. The man sitting down shows where Binks could walk, or more often shimmy along the floor to work on the engine. The man in the center stands where the engine will be placed. In this photo, with the engine installed, you can see the narrow space on either side where Binks worked. Imagine working within a few inches from this 650 horsepower monster. It was originally mounted on a locomotive. It filled the car with a sound so deafening that Binks filled his ears with plasticine and cotton to protect his hearing. Yet as amazing as this is, the most stunning moment of his day was getting to and from work. As the airship zipped along at 60 plus miles per hour, Joe Binks climbed from the belly of the ship down the ladder into the car. The propeller spun with such force that its prop wash could lift him parallel to the ground, turning him into a human flag tethered only by his tenuous grip. Not only did the British develop this naval airship, they also created the necessary infrastructure. For example, to land this giant ship, the British developed a mooring tower because they thought ground landing too difficult for an airship of this size, although Germany always used ground landings for its zeppelins. The ship approached the tower, dragging a cable which was then hooked to the tower cables on the ground. And then at the tower space, steam powered winches pulled the ship toward the tower. In 15 or 20 minutes, our 101 latched to an arm extending from the tower. And then there was a flurry of activity inside the tower head as crew secured the ship. The mooring tower could withstand a 30-ton pole at its top. Each of its four legs was embedded in a piece of concrete about 12 feet square that extended 6 feet into the ground. The tower offered an easy way to supply the airship with water, fuel, and hydrogen. Huge pumps at the base could lift 5,000 gallons of water per hour and pump fuel at 2,000 gallons per minute from the 10,000 gallon tank buried in the ground near the tower. At the tower, passengers boarded via a flexible bridge that had a chill-inducing view of the ground 170 feet below. Yet the boarding could be even more thrilling. Wheels on the bottom of the bridge allowed it to revolve around the tower as the ship swung with the wind. Unlike the Zeplins that preceded it, our 101 had a novel feature. The passengers rode inside the body of the ship, not in a car hung from the ship. They built in an elegant dining room. The cutlery and tableware were blazoned with the Royal Airship Works crest. As passengers dined, the airship steward stood against a wall with his back straight and his chin raised. His appearance was spick and span, said a crew member. He planned and organized the meals. His goal was seven course meals comparable to those of the best London hotels. A large, brightly lit lounge the size of a tennis court spanned the width of the airship. Its polished wood floor gleamed in the sunlight that spilled through giant windows, port and starboard. On this floor, the airship's designers planned for passengers to foxtrot all night as the airship flew to India. At the end of each lounge were the ship's master stroke, the promenade decks. As passengers relaxed there, they enjoyed a stunning panoramic view of the ground through large glass windows tilted at 45 degrees. Beyond the passenger quarters, R101 had an unusual feature for an airship, a smoking room, even though the ship carried over 5 million cubic feet of flammable hydrogen. On these delicate gas bags rested many hopes and dreams. Yet the ship was not up to the task. The Royal Airship Works technical staff concluded, after studying data from R101's test flights over the United Kingdom, that the ship didn't have the lift to fly to India. It was too heavy. Partly this was because R101 deviated from the time-tested principles used in zeppelins. An airship framework of that era was composed of a series of rings. Zeppelin engineers built strong yet light frameworks from thin, flexible, circular rings, which were then stiffened by radial wires drawn taut. The wires functioned like the spokes of a bicycle wheel. In R101, the wires were eliminated and the rings were made much thicker. This resulted in a heavier framework. This decreased the amount of lift available for fuel, so much so that on R101's return trip from India, the technical staff calculated that the ship would not be able to complete the first leg of the 2800-mile journey from Karachi to Ismalia. R101's fuel, they estimated, would run out over the desert in Saudi Arabia. The ship would float with its engine stalled 500 miles or so from the mooring tower in Egypt. To ensure that such a failure would not occur, the technical staff devised an audacious plan. In this photo, you can see the results of that plan. At the top is the airship in late June and at the bottom, six weeks later, the ship has been lengthened from 735 to 777 feet. The technical staff split the ship in two, inserted a section of framework and added a gas bag to gain enough lift to carry fuel. A short time after R101 was split in two and lengthened, it departed the Royal Airship Works for India. The airship departed the mooring tower on October 4th, a few minutes after 6.30 p.m. Greenwich Mean Time. On board were 54 people, 48 crew or members of the Royal Airship Works, and the rest observers and dignitaries, including Britain's Secretary of State for Air. The purpose of this flight was to demonstrate R101's ability to travel to India. But as it traveled across England, over the Channel and into France, the ship encountered bruising winds and pelting rain. Winds so fierce that often it traveled at a ground speed of only 30 miles per hour. At a few minutes past two in the morning, about 40 miles, 64 kilometers north of Paris, R101 chopped through the turbulent air at an altitude of 1200 feet just below a layer of clouds. The cover on top of the airship split open. The ship pitched down. The ship's crew used the elevators to restore the ship to horizontal. It was now 500 feet above the ground. The control car signaled for the engine power to be cut, and R101 dove nose-first to the ground. Then slid into a grove of hazel and oak trees. It burst into flames as navigational flares ignited the hydrogen. The imposing R101, the great machine to connect the vast geographic sweep of the British Empire, was now a tangle of debris on the ground. Only the rudder at the stern still stood tall. Rags and strips of fabric hung from it and fluttered in the wind, the center section rocking on its hinges, swinging aimlessly. 60 feet in the air at the tip of the stern, almost untouched by any flames, the ship's RAF instant flapped in the wind. The Union Jack on the flag was partly burned, but the RAF roundel was intact. Long gone from most of the framework were the delicate gas bags and plasticized cloth cover, both vaporized by the raging fire. The polished metal exterior of a crushed engine car glistened in the flames. The collision with the ground rotated the car 180 degrees. It's propeller now facing the wrong way. From this debris, a charred crew member rose, but then fell back into the flames. Inside, an engineer, his body carbonized, still clutching a wrench in his hand. The ground was littered with everyday articles, suitcases, fur lined boots, charred shaving brushes, a tin of cigarettes, and a ticking watch. The stores were strewn on the ground while few loaves of bread and a still labeled tin of plums its juice leaking from the can. After a few minutes, the only sound was the hiss of rain evaporating as it struck the smoldering wreckage. One of the few survivors, only six of the 54 survived, was Joe Binks from the rear engine car. The rest were buried in a communal grave near the Royal Airship Works in the United Kingdom. Each coffin was adorned with a small label fabricated for the Medal of R101's framework. 14 of the plates born names, but the others were never identified in the wreckage. Their coffins read to the memory of the unknown airman who died on October 5th. There's a little bit more to the story. In a sense, the airship flew again. The wreckage of R101 was hacked to pieces using blowtorches, chisels, and metal saws. The compacted 80 ton framework was transported to Sheffield where it was melted to scrap and then sold to the Zeppelin Company. They used it to create the Zeppelin LZ-129 an airship better known as the Hindenburg. If you'd like to learn more, you can read my book, Fatal Flight, The True Story of Britain's Last Great Airship. You can listen for free to the complete audiobook, details at engineerguy.com slash airship, or if you prefer, you can listen right here on YouTube. I've listed the link in the end card. I'm Bill Hammack, The Engineer Guy.