The future of airships is smaller than you think
When you hear the word ‘airship’, do you immediately get a mental image of a gigantic zeppelin that is bursting into flames?
No wonder, since the tragedy of the Hindenburg, the largest airship ever built, has left its mark in our collective memories and still affects our common perceptions of airships and blimps. “The concept of an airship is doomed to fail”, “the use of hydrogen can never be safe” and “there is no use for airships in the era of aeroplanes” are common statements about lighter-than-air vessels.
But what if we said that the number of airship accidents is actually relatively small in relation to the huge number of operational hours?
What if we took a deeper look into the reasons behind the hydrogen airship disasters that many times were linked to detached parts or ignition of fires that had nothing to do with hydrogen? What if we took into account that airships were actually used in the US navy long after the Hindenburg disaster (with only one blimp lost in battle) — until the 1960’s when jet planes and the desire to go faster took over the aerospace industry?
However, the laws of physics don’t change. The concept of a lighter-than-air vessel is not outdated — but on the contrary, it is more topical than ever. Like Carl Sagan put it:
“You have to know the past to understand the present.”
Only by understanding the fundamentals of lighter-than-air vessels and learning from all the trial and error experiences of the past, we can develop something new. Something that might actually be smaller than you think. Something that will change the whole philosophy of use of airships.
But first, let’s take a look at the history of airships, to understand where it all started.
How did the idea of an airship develop?
The first person to sketch an idea of a “vacuum airship” was Italian aeronautics pioneer Francesco Lana de Terzi in 1670. His visualisation of the airship was more like a sailboat, with a central mast to which the sail was attached.
The vacuum would be produced with the help of four masts that had thin copper foil spheres attached to them. Once the air was pumped out of the spheres, a vacuum would form inside — and thus being lighter than air, it would provide lift.
However, this idea never realized, as at that time no one could produce such thin copper foil, and the spheres could not have handled the pressure.
To this day, we do not have materials that would allow building a vacuum airship that would be light enough. It would have to endure the pressure of the whole atmosphere since there is nothing inside to resist it — which doesn’t sound good at all as the weight of the atmosphere is over 10 tonnes per square meter which equals the weight of a 10-meter layer of water. Therefore, the idea of a vacuum airship has been abandoned as not realistic — a myth that no one in the field of aerospace engineering needs to bust.
However, the idea of a flying ship kept enticing people and soon they started experimenting with new airship designs — this time with balloons filled with hot air. As buoyant force is the weight of the displaced air, it is a more usable alternative to vacuum airships — as it is much easier to make a light envelope and fill it with lifting gas that weighs almost nothing than try to resist the whole weight of the atmosphere with a vacuum.
After people learned to use hydrogen, they started filling the balloons with that — allowing the manufacturing of airships that could float in the air, but could not yet be controlled because of the lack of propulsion. There was one airship that ran by a steam engine, as well as many attempts to use manpower, but the biggest game changer was the development of combustion engines in the late 1800’s.
Airships owe a lot to the Wright brothers who made the world’s first controlled flight on a motor-operated airplane in 1903. It was heavier-than-air, but the engine and the first proper propeller were achievements that greatly improved the performance of the early airships.
A certain gentleman, German general Ferdinand von Zeppelin was fascinated by the idea of using multiple balloons to lift a vessel up in the air. He was pursuing a military career when he decided to take leave to act as an observer for the Union Army during the American Civil War.
There he got to learn about observation balloons that were used for artillery spotting and got inspired: “what if you put several of these balloons together and cover them with fabric?” He then formulated the basic principle of a vessel that he realized after resigning from the army: a rigidly-framed outer envelope containing pockets of lifting gas — later known as a zeppelin, which marked the transformation from gas-filled blimps to the era of rigidly-framed zeppelins.
The golden era of gigantic zeppelins — maybe it was safer than you think?
The plain and simple reason for the massive size of the early airships was that it was easier to make them fly. As the airships had to carry everything with them, including heavy engines, fuel, control systems and a large crew, the buoyant force had to be big — i.e. the vessel had to displace a lot of air.
In addition to military purposes, airships were used to transport cargo and passengers. For instance, the British Empire wanted to develop airships to be used for mail and passenger transport to the distant corners of the Empire, such as India and Canada, because the heavier-than-air aircraft of that time could not have handled such distances.
The size and volume of the airships grew and grew — because obviously you had to be able to install a full set of oak furniture on the vessel, not forgetting the fluffy plush carpets or a grand piano, either!
Most American airships in the 1920s used helium for lift, and as a non-flammable gas it was the safest bet at that time. However, helium was also rare and expensive and only available from the U.S. And when the U.S. banned the export of helium in 1927, it forced the rest of the world to use hydrogen instead, including the Germans who also had to convert the Hindenburg from helium to hydrogen.
To some extent, hydrogen was a better alternative: it could be produced easily and with low cost, and as it produced a stronger lift, a few extra passenger cabins could be installed onto the vessels. Of course, due to the extreme flammability of hydrogen, extra precautions needed to be taken when building airships such as the 245-meter-long Hindenburg with an astonishing gas capacity of 200,000 cubic meters.
However, when you look at the reasons behind fatal airship crashes, you see exaggerated payloads, flying in bad weather, tears in the structures… But not a single hydrogen explosion. For instance, the British R-101 flew into extremely bad weather, experienced a tear in the forward cover that led to a deflated gasbag. Another example is the USS Akron which flew into a storm and lost its lower rudders that disabled all control of the airship.
The accident of the notorious LZ 129 Hindenburg
Let’s go back to the initial mental image: A zeppelin bursting into visible flames… Wait, doesn’t hydrogen burn with a pale, invisible flame?
Indeed. While the source of the initial fire that led to the destruction of the Hindenburg still remains unclear, we do know that it did not explode.
After performing 62 successful operations, the 63rd landing was the fatal one for the LZ 129 Hindenburg, the largest lighter-than-air vessel ever built. It was 245 meters long and 41.2 meters in diameter with a record speed of 135 km/h. The vessel caught fire and it only took approximately 50 seconds before it hit the ground.
Of the 97 people onboard, 13 passengers and 22 crew members died, in addition to the one ground crew member, resulting in a total of 36 lives lost. Unfortunately, most of the people who died had jumped off the aircraft, while those who survived had run out from the burning vessel.
You can always speculate — was it was the electrostatic discharge of the thunderstorm that ignited the fire, as the vessel had to let out some hydrogen while landing? Could a more fire-resistant fabric covering have prevented the fire — instead of the fabric that was treated with chemicals containing extremely flammable metal compounds?
Whatever the reason for the unfortunate accident was, it marked the end of the development of large-scale zeppelins — quite literally, as the Germans recycled the scrap from the Hindenburg to build military planes.
However, the use of airships continued long after the Hindenburg disaster. The US navy used fleets of non-rigid airships, also known as blimps, in WWII in submarine patrolling — in an attempt to protect cargo ships from attacks. The patrolling was much needed as only one airship-guarded convoy was lost in comparison to 500+ unprotected ones. The blimps also carried bombs or gave orders to naval ships.
Regardless of the reliability of hydrogen-filled naval blimps at that time, the emergence of jet planes, space rockets and supersonic aircraft in the 1950–60s made lighter-than-air vessels look highly inefficient and slow. It was all about speed and futuristic thoughts — and airships did not fit this ideal. All in all, the golden years of airships lasted a good 50 years before jet planes took over completely in the 70s.
But why is the future of airships small?
That brings us to this day, when we are seeing a resurgence in the commercial development of airships. Several companies, big and small, are currently developing their own version of Count von Zeppelin’s initial prototype. In the U.S., they are mostly developed for military purposes, whereas some other companies are seeking to develop the ultimate low-carbon transportation method.
Low-carbon and zero-carbon transport is a high priority on the EU’s agenda, and climate change is an issue that the aviation industry also needs to take responsibility for.
What is in common with the modern versions, is, again, the size. Most of them attempt to lift a huge object and move it to another location. Which like we saw from the history of airships, can definitely be done.
If you want to lift a truckload of timber or a battle tank, your vessel has to have the lifting gas capacity of tens of thousands of cubic meters. You also need a lot of space for ground handling and storage (which actually is the most hazardous part of airship aviation) — and a huge airfield that lets your aircraft land in any weather.
However, we at Kelluu, an airship company from Finland, have taken a whole new approach to the concept of a lighter-than-air vessel. Our airship doesn’t even attempt to be large. On the contrary, it is small, around the size of a passenger car.
We figured that the principles of lighter-than-air aviation work best when we do not even attempt to carry heavy payloads — but instead, we transport something that is lightweight but highly valuable: data.
Our airships can do whatever modern-day sensors can do, as they are just big enough to carry any kind of sensor to any location, near or far. The “brains” of the vessel are the size of a matchbox — meaning a pile of electronic components that act as the pilot and co-pilot. The vessel is connected to a mobile data network and it can transfer the data in real time.
Due to their small size, we can easily produce fleets of Kelluu airships that can collect data from vast areas at the same time. As Kelluu airships are blimp-like, lightweight shuttles, they can be operated with a minimal amount of fuel for weeks on end.
We use hydrogen as a lifting gas and fuel for the fuel cell that provides the electric current for the electric components — the only by-products being heat and pure, clean water. Hydrogen is also easily available — 73 % of the mass of the universe is hydrogen — whereas the mass production of helium is a trickier process.
What Kelluu truly revolutionizes is the price and environmental-friendliness of data collection. By replacing for instance highly polluting helicopter flights with fleets of hydrogen airships, we can reduce CO2 emissions by over 99 %, while the actual airtime is much longer compared to drones or helicopters.
Of course, our work is about constant precautions — as following strict safety protocols and ensuring 100 % fire safety is a part of our everyday work with the dangerously flammable gas that in the right hands offers unbeatable lift and long operating hours.
If we compare a Kelluu vessel with the Hindenburg, we are talking about 1/10 000 of the volume. So, when it comes to flying in challenging weather conditions, for instance, storm winds treat a Kelluu airship much more gently than a rigid-framed zeppelin the size of the Titanic (like the Hindenburg was).
Where would such small vessels be used then?
Obviously, the fields of application are infinite for this kind of vessel when you choose the sensors according to the data needed. Thousands and thousands of kilometers of oil or gas pipes in this world need constant monitoring. Vast forests can burn endlessly if there is no one to report fires. Information from accidents or crisis areas is crucial to get. Weather data could be collected easily from hyperlocal points.
However, the first, already confirmed field of application is the energy industry. A fleet of Kelluu airships will soon be monitoring the status of power lines in remote areas. They can report any damages or potential threats in areas that can be almost impassable on foot.
Real time data that is obtained from remote locations via airships is truly valuable, when the limited human resources can be directed to fixing the potential threats before a major power outage even happens. When you compare the cost of a fleet of mass-produced, smart autopilot airships to manned helicopter flights and ground crew monitoring — well, the equation is easy to solve.
So, when we say that the future of airships is smaller than you think, we’re only referring to the physical size of the modern airship. We believe that the future of small-sized airships is big and bright.
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