Picture Credit: hakelbudel
May 6, 1937 German 245-meter airship “Hindenburg” ignited when landing near New York and in a few minutes burnt down almost to the ground. In the fire killed 36 people, and since then the former glory of airships has declined. Now no one will remember how these majestic giants once crossed the Atlantic or frightened civilians during the First World War. However, in the future everything can change.
Due to what airships are kept in the air
The most important thing in an airship is a shell filled with gas lighter than air, through which a hydrostatic force is created, pushing the airship up. In this way they are like balloons, but unlike them, airships can not only move up and down in the oceans of air, but also freely move horizontally, along the surface of the earth – even without a tailwind.
Depending on what is filled with their shell, airships can be of two types: thermal – their shell is filled with heated air (its density is less than the density of ambient air) – and gas. Previously, the gas blimp was filled with hydrogen – the lightest of gases, but because of the explosive nature of hydrogen-air mixtures, engineers switched to a neighbor of hydrogen according to Mendeleyev’s table – an inert gas helium.
Another airspace is classified by type of construction. They can be soft – their shell resembles a huge ball, the shape of which is maintained solely by the pressure of the gas. They can be semi-rigid when the lower part of the shell is enclosed in a metal frame, which gives rigidity to the whole structure. And finally, airships are just tough – then they have a fixed form, supported by a skeleton.
By the way, the classical cigar-shaped form is not typical for all airships: they are ellipsoidal, toroidal, lenticular, and sometimes resemble flying saucers.
How to fly a dirigible
Vertically, the airship moves, changing its lifting hydrostatic force. In thermal airships, it is possible to change the temperature of the injected air, because of which its density and, correspondingly, the lifting hydrostatic force change. In gas airships, inside one large shell, there are smaller containers – ballonets, into which the atmospheric air can be pumped or pumped out, thus controlling the total density of gas inside the airship.
For movement along the surface of the earth, airships are supplied with internal combustion engines creating a horizontal thrust. In addition, the airships are given a streamlined aerodynamic shape, and therefore during the flight an aerodynamic lift force acts on them, akin to the one that acts on the wing of the aircraft.
Even the airships usually have several ballonets in the stern and bow of the ship. This gives extra room for maneuver: the airship team can, by inflating the ballonet, tilt the aircraft either “forward” or “backward”.
It is important to understand that a well-loaded airship is not always lighter than air, and then besides the pushing aerostatic force, additional vertical-traction motors and lifting aerodynamic forces help it to stay in the air. So managing an airship is not an easy task. The team needs to monitor the filling of the shell and ballonet, the work of a variety of engines and be controlled by numerous aircraft gear that regulate aerodynamic force.
What is Zeppelins
Zeppelins are, in a sense, “Xeroxes.” In English, the word zeppelin means “airship”, but in reality it is only one brand of dirigibles of a rigid design produced by the German company Zeppelin GmbH from 1899 to 1938 and named after its creator, Count Ferdinand Zeppelin. In total, the Germans made 130 Zeppelins: some were put into the army, and some were for civilian transportation of people and cargo.
Most of all watches among all zeppelins flew LZ 127 Graf Zeppelin. It was a huge airship with a volume of 105,000 cubic meters, a length of about 236 meters and a maximum diameter of 30 meters. Under the keel of its shell was hung a few nacelles for engines, as well as a large gondola for passengers and crew, which among other things housed the captain’s cabin, technical rooms, ten double cabins, a spacious wardroom and a separate room with washbasins.
Flight on airships in general and Zeppelins in particular were much more comfortable than on the then aircraft. Of course, the designers tried to reduce the load of the aircraft, but all the same, because of the enormous carrying capacity of the airships, they had far more opportunities than the aircraft designers. Sometimes this led to strange compromises: for example, on the follower LZ 127-LZ 129 “Hindenburg” – a lightweight piano made of an aviation alloy of duralumin was installed in the wardroom.
In total, the LZ 127 flew 1.7 million kilometers or 17,200 hours. In total, he transported 13,000 passengers, made 590 flights to various countries of the world and 143 times crossed the Atlantic.
Airships – is it dangerous?
Picture Credit: skeeze
“Graf Zeppelin” was filled with hydrogen and flew without serious accidents all nine years of service until it was dismantled for metal. But even then the Germans understood that this was very dangerous, and therefore the “Hindenburg” was laid as a gas airship filled with helium. In reality, everything turned out differently. The right amount of gas could then only be bought in the US, and the Americans imposed an embargo on the export of helium. After the German side agreed on special conditions for the purchase of gas, but during this time the Nazis came to power in Germany, and as a result, the Nazis banned the import of expensive helium from America, which could be replaced, in their opinion, by their own hydrogen.
As a result, the huge “Hindenburg” (it was even larger than the “Count Zeppelin” – 200 thousand cubic meters of volume, slightly more was only the last Zeppelin LZ 130) was slightly altered and filled with hydrogen. To avoid danger, the Germans even introduced some strict rules on the airship: all passengers and crews were confiscated by lighters, matches and other sources of fire before landing, and smoking on the ship was possible only in the smoking room, separated from the rest of the rooms by gas valves. But none of this helped the evening of May 6, 1937.
By that time the Hindenburg, launched on March 4, 1936, had already completed 63 flights, and the new one was little different from the previous ones. The airship flew from the German city of Frankfurt am Main, crossed the Atlantic, flew over New York (the captain even spent the “Hindenburg” as close as possible to the Empire State Building – so that passengers and townspeople would wave their hands in delight) and set off To land at the airbase of Lakehurst, about 135 kilometers south-west of New York. There was inclement weather, and the airship was circling for some time over the base, but then he was allowed to land and he successfully moored to the airship mast.
A few seconds later, an explosion occurred, and, blazing, the airship fell down on the ground in a few minutes. On board there were 97 people, 36 of them died. Someone gave out a flaming construction, someone received incompatible with life burns, and some crashed when in a panic they jumped from the airship to the ground. Later the commission decided that the accident was caused, on the one hand, by the depressurization of one of the cylinders with hydrogen mixed with air, and on the other – by the spark that had slipped in this explosive atmosphere due to the weatherproof of the shell that was electrified in the moist air.
In the history of airship construction there were also more terrible catastrophes. For example, in 1933, due to piloting mistakes, the American military airship USS Akron fell into the Atlantic due to piloting mistakes (73 of 76 people died, the majority was due to frostbite). But it was the collapse of the “Hindenburg” that was the beginning of the end of the airships. The catastrophe painfully struck the image of fascist Germany. The Germans at first forbade their airships to transport passengers and make any international flights, and then completely curtailed the production of Zeppelins and let the last of them to scrap.
In World War II, Americans still used airships for military purposes, but it was already the decline of former glory.
Airships in the War
Yes, in due time these hulking designs, reminiscent of huge whales, were a very dangerous weapon. In 1908, Herbert Wells in the book “War in the Air” described the bombing of airships, destroying whole cities, and soon his predictions began to come true.
At the beginning of the First World War airships were almost invulnerable. They flew at such a high altitude that it was difficult to knock them off the ground, and from the air-fighters of that time it was hard to climb to such a height. As a result, the same Zeppelins could almost attack the enemy with impunity.
The most famous case is the bombing of London on the evening of September 8, 1915. At about two o’clock in the afternoon three airships flew from the German airbase, two of them turned on their way because of emergency situations, and the third by eight o’clock in the evening reached the coast of the British Isles. There he waited for darkness and farther, at an altitude of 2,800 meters at a speed of about 100 km / h, no one noticed reached London. In the city, then, rules of light disguise were introduced, but in fact no one observed them. Brightly lit streets, embankments – an airship against the backdrop of this exposure and flew undetected to the very center of the city. As a result of the bombing, 22 people were killed and 87 people were injured. The British realized that they were not as invulnerable as it seemed.
Later the troops were able to withstand the airships. Anti-aircraft guns became more distant, air defense calculations worked more accurately and accurately, and the planes learned to climb above the airships and drop bombs on them. By the end of the First World Airships were no longer such a formidable weapon and their military functions began to change. In the Second World War, the US Navy used soft airships with a volume of 12-18 thousand cubic meters no longer for bombing ships, cities and various land targets, but for fighting submarines. The airships tracked them down and attacked them with depth charges, while they themselves remained relatively safe for obvious reasons.
Continued to use airships and after the Second World – most often for radar reconnaissance.
Airports for airships
At the dawn of airship construction with landing of airships, everything was very difficult. A few 200-meter ropes were thrown from the ship, and on the ground a mooring crew consisting of tens or sometimes hundreds of people had to tie them to the ropes on the mooring mast, using a winch to pull up to it a huge airship and fix its nose in the docking bay. After this, the airship could as a weathervane rotate around its mast.
Accordingly, for all this, we needed special masts, and a skilful team that could gently handle this physically challenging task. But gradually the technique developed, the mooring became semi-automatic and much simpler.
The hangars for ground parking of airships are another matter. Because of the huge size of the aircraft themselves, they must be so large that hangars of airships with a carrying capacity of several hundred tons are thousands of times larger than the size of hangars for airplanes, and of course they can not replace any warehouse or ancillary facilities.
Airship “Hindenburg” at the airbase of Lakehurst after the first transatlantic flight.
Photo: Wikimedia Commons
Airships against aircraft: minuses and pluses
Reality shows that there are more minuses in airships. First, load-lifting airships are always huge (hydrostatic force is small, and in order to raise with it a clear payload, the volume of working gas in the shell must be very large). Secondly, because of the large aerodynamic resistance of airships, the smallest speed limit is not more than 150 km / h. In addition, the shells of airships are constantly torn and broken, and for the stay of airships on the ground huge hangars are needed. As a result, ordinary people in everyday life with airships only face air shows or various sporting events, where they are traditionally used as carriers of advertising.
On the other hand, airships have their advantages: their stay in the air is almost free (because they are kept at the expense of hydrostatic force) and is not very limited in time; The carrying capacity of airships is much less limited by the structural properties of the hull materials than airplanes (more shell with gas – more cargo can be lifted); Airships do not require a runway; Use much less powerful engines and, accordingly, less pollute the air; The course of airships is much more stable than the course of helicopters (therefore they can be used as “air taxis”).