Discovery Ch Massive Engines_09of10_Airships
Transcript
00:00The Zeppelin airship Hindenburg, 7 million cubic feet of hydrogen for lift and four massive
00:24diesels for forward propulsion, together the largest ever flying engine, and the most infamous.
00:41I know what you're thinking, big Zeppelin, masses and masses of hydrogen going boom,
00:46big disasters, bye bye airships. But no, these were brilliantly designed complex machines.
00:53There was nothing wrong with the design of the Hindenburg. The hydrogen didn't explode
00:58and there was a completely different reason why it was destroyed. And one day soon, giant
01:03airships of this size may fly again.
01:07Need more lift. Need more lift.
01:19For centuries before the first engines were invented, humans dreamed of taking to the
01:24skies.
01:26It wasn't until medieval times that people even realised that air had substance, that
01:30this stuff was in fact stuff. And that Archimedes' ancient principle of objects floating in his
01:37bathtub could in theory be applied to objects floating on air.
01:41Unfortunately, even the fittest humans don't have enough muscle power to lift their own
01:46weight up into the air.
01:49But in the 18th century, a couple of French paper manufacturers, the Montgolfier brothers,
01:54stumbled on the solution that had been staring us all in the face since Neanderthal times,
01:59that hot air rises.
02:01The story goes that the Montgolfier brothers were inspired by a piece of paper rising above
02:06their bonfire.
02:09The other version is that Joseph's wife had hung her chemise out to dry in front of a
02:13fire and it took flight.
02:17It was probably the wind. Less plausible, OK, but maybe it explains why balloonists
02:23to this very day insist on using oversized laundry baskets as their passenger compartments.
02:31After so many people had talked so much hot air about human flight for so long, the Montgolfiers
02:36solution, the first aero-engine, was a bag of hot air.
02:41Hot air balloons work because when air is heated, it expands, it becomes less dense.
02:46So the hot air inside the balloon is lighter than the cold air outside it.
02:50Let's see if it works.
02:55The Montgolfiers' first pilots were a cockerel, a duck and a sheep, which flew over Paris
03:00in a big balloon for several hours in 1783.
03:06Then followed by even bigger balloons carrying the first human passengers.
03:14But right from the beginning, balloons proved very hard to control.
03:19On a windy day, the only place to fly is indoors.
03:24This is called a skyhopper, a one-man balloon with no laundry basket.
03:29In the balloon, there's 31,000 cubic feet of hot air, which is enough to keep me, me
03:35engine and me fuel tank up in the air, as you can see.
03:43The controls couldn't be simpler. To go up, create more hot air.
03:50To go down, simply wait for the hot air to cool and the balloon slowly sinks.
03:58The problem with a hot air balloon is that it's very hard to control where you're going.
04:02You're at the mercy of the wind, or in my case, the odd draft coming through the hangar doors.
04:10Of course, what I need is a propeller, which can move me in the direction I want to go.
04:17It can even move me head on into the wind.
04:24And a propeller means another engine and more fuel, and that means more weight.
04:28And if I've got more weight, I'm going to need more lifting power.
04:33The solution invented just a few years after the Montgolfiers was a much more efficient
04:37type of balloon.
04:39Airships became possible with the invention of a new lighter-than-air lifting engine.
04:44Just as hot air is lighter than cold, hydrogen gas is lighter than the mixture of nitrogen
04:49and oxygen that make up air.
04:54In theory, one cubic metre of hydrogen can lift one kilogram.
04:59Right, let's have liftoff here.
05:03One last match out and I think that should be it.
05:07I think we do. Up we go.
05:12John Mousavich, enjoy your flight.
05:17This is helium, by the way. It doesn't have a lifting power of hydrogen, but it's also
05:21not dangerously explosive.
05:24A gas balloon gives you just as much lifting power as a hot air balloon, but with no burner
05:29or tank of fuel, it weighs a lot less.
05:35With no burner to turn on or off, gas balloons rely on other methods to control altitude.
05:40To go up, you remove ballast, like so, and to come down, you vent a bit of gas.
05:53The lifting power of lighter-than-air gases made airships possible.
05:58Now you can add the extra weight of forward propulsion engines and propellers.
06:04As long as you do one thing, you've got to think massive, and a very clever chap from
06:09Lake Constance in southern Germany certainly knew how to do that.
06:14Count Ferdinand von Zeppelin was born in 1838, just over there in the town of Constance.
06:19He returned here over 50 years later to build the world's largest and greatest airships.
06:25A military man, his dream was to provide the fatherland with the ultimate weapon, a world-conquering
06:30flying machine.
06:33Early attempts at airships had used steam engines, but these proved too heavy and not
06:38powerful enough to fly into the wind.
06:43What was needed was a lighter, more powerful type of engine, like this one.
06:47It may not look very light, but this early Daimler petrol engine produced 110 horsepower
06:52and weighed 533 kilos, a far better power-to-weight ratio than any steam engine.
06:59It was originally designed as a car engine.
07:01On an airship, the pistons inside these four cylinders drove a propeller instead of the
07:06wheels of a car.
07:10The internal combustion engine was also much safer than a steam engine.
07:14There were no naked flames or sparks to ignite stray hydrogen, and safe, inert helium wasn't
07:20available at the time.
07:22To be an effective military aircraft, Count Zeppelin wanted plenty of power.
07:27So he came up with a way of making very big airships that could carry several petrol engines.
07:35He pioneered the idea of the rigid airship.
07:38Instead of using a single bag of hydrogen, his Zeppelins used a framework structure inside
07:44which a series of hydrogen bags could be inflated.
07:48All that hydrogen made a very powerful lifting engine, and the framework also made Zeppelins
07:54aerodynamically streamlined.
07:57The envelope fabric provided insulation, keeping the gas bags cool to prevent the hydrogen
08:02expanding.
08:04Like modern lighter-than-air balloons, Zeppelins were fitted with gas valves designed to safely
08:08release hydrogen should the pressure become dangerously high.
08:12They also had these smaller controllable valves which could vent a little bit of gas to control
08:17the altitude, but the better the gas balloons were insulated and kept at a constant temperature,
08:24the less venting was needed and the further the airship could travel without necessitating
08:28a hydrogen top-up.
08:30At 8pm on July 2nd, 1900, three years before the Wright Brothers first took to the air,
08:38Count Zeppelin personally piloted his LZ-1 on its maiden flight.
08:44Its success inspired the Count to build bigger and bigger airships with more and more powerful
08:50engines, and he established the world's first domestic airline service.
08:56By the outbreak of World War I, over 34,000 people had taken their first flight on an
09:01airship.
09:02One early passenger, Nobel Prize winner Hermann Hesse, wrote,
09:05I close my eyes and can feel that sensation of floating lightly and gently through the
09:10air.
09:11I know for certain that as soon as I find an opportunity to fly again, I will do it
09:16with the very greatest of pleasure.
09:21Following World War I, the airship finally fulfilled Zeppelin's original vision as a
09:26machine of war.
09:30On the 31st of May, 1915, London became the first capital city to be bombed from the air.
09:38At first, the Zeppelins had a huge advantage.
09:41They could fly at over 4,000 metres, well above the height ceiling for early fighter
09:45planes.
09:46With the war over, aircraft engines and anti-aircraft guns improved, and by the end of the war,
09:5177 airships had been shot down.
09:54By the time of Count von Zeppelin's death in 1917, they'd been discredited as a useful
09:59military weapon.
10:01As it turned out, his airships would transport more passengers than bombs.
10:08The Zeppelin factories were closed down until 1928, when the company returned to business,
10:14building a massive new airship, the Graf Zeppelin.
10:17Designed to compete with early fixed-wing airliners that were limited to short hops
10:21of just a few hundred miles, this airship was capable of flying non-stop for thousands
10:27of miles at speeds of up to 80 miles an hour, thanks to a radical new propulsion engine
10:32that could be serviced during flight.
10:36You can see there's just enough space around the engine for some regular maintenance and
10:40emergency repair work, but given the noise, the heat and the fumes, it must have been
10:45a pretty daunting job.
10:47But the most innovative thing about this engine was that it ran on a gaseous fuel called blaugas.
10:53Blaugas was a mixture of gases, including hydrogen, that altogether weighed almost exactly
10:59the same as air.
11:02The Graf Zeppelin was an experimental prototype for a new era of international air travel.
11:08It was 237 metres long and was filled with over 100,000 cubic metres of hydrogen in 17
11:15gas cells.
11:16Its 20 passengers were outnumbered by 43 crew.
11:20It had luxurious cabins and saloons, and a kitchen and a dining room.
11:25Plus, it was capable of flying non-stop across any ocean.
11:31The invention of the airship combined lifting engines with forward propulsion engines to
11:35produce the world's largest flying machines, machines which dominated passenger and military
11:41aviation well into the 20th century, until May the 6th, 1937, to be precise.
11:56It uses hydrogen as a lifting engine and diesel to go forwards.
12:02It's the most massive engine ever built, but tragically, it turned out to be a flying bomb.
12:09Welcome aboard the Hindenburg.
12:15Double the size of the Graf Zeppelin and double the luxury.
12:19This is an accurate reconstruction of one small section.
12:23Everything was interior designed in the latest Bauhaus style.
12:28A luxury floating hotel that accommodated 72 passengers and 40 crew.
12:34Even the toilets were stylish.
12:38250 metres long and 40 metres in diameter, this was the world's largest ever flying machine,
12:46and a masterpiece of design and engineering.
12:49Behind the scenes, the structure looked like this.
12:52Above here were 16 enormous gas bags containing 7 million cubic feet of hydrogen.
12:59That's a lifting engine capable of carrying an incredible 600 tonnes.
13:03Much safer, inert helium was now available, but the United States had a monopoly on supplies
13:09and they weren't prepared to sell it to Nazi Germany.
13:12What Germany did have was state-of-the-art diesel engines.
13:15The Hindenburg used four massive 16-cylinder diesel engines.
13:20By the 1930s, this type of engine had become the ideal solution for airships.
13:25Compared to a petrol engine, diesel engines are much more low-revving and generate more
13:29torque, that's the twisting force on the crankshaft.
13:35The new diesel engines proved more reliable and much more fuel-efficient than petrol engines,
13:40and together produced a total of 4,000 horsepower for a top speed of 82 miles an hour.
13:46She was designed to withstand even a severe storm.
13:50All in all, the Hindenburg was about the same size as RMS Titanic, just as luxurious and
13:56capable of flying to New York in just three days, half the time it took by steamship.
14:03On the 6th of May 1937, the Hindenburg was approaching Lakehurst Naval Air Station near
14:08New York at the end of her 11th transatlantic flight, when the weather deteriorated.
14:16While attempting to land, disaster struck.
14:19In just 37 seconds, the great airship was reduced to its crumbling lightweight frame.
14:26The Inferno was blamed on a hydrogen leak, perhaps ignited by a lightning strike.
14:32It was the first major disaster of its type caught on newsreel, and the shockwaves spread
14:37around the world.
14:43Just when public confidence in airships was reaching an all-time high, a tragic series
14:48of events culminated in the Hindenburg disaster, and in an instant, the airship era was over.
14:54Or was it?
14:56Sixty years on, plans are afoot to build a new generation of massive airships, even bigger
15:01than the Hindenburg.
15:02Are they mad?
15:04Well no, thanks to new evidence that disputes the original theory as to why the Hindenburg
15:10crashed.
15:15In the early 1990s, a NASA scientist based in Florida investigated an alternative theory.
15:22He believes the Hindenburg had a fatal design flaw, but one that had nothing to do with
15:26the use of hydrogen, and more to do with a dodgy paint job.
15:31Dr. Addison Bain's theory is that a build-up of static electricity ignited the chemicals
15:37used to coat the outer fabric of the Hindenburg.
15:40This is an actual piece of the Hindenburg, look at that.
15:46On the other side we can see the original stitching, history before our very eyes, fantastic.
15:52Zeppelin coated the envelopes of his airships with a gooey substance known as dope.
15:56The chemicals in the dope provided weather protection, they made the hull smooth and
16:00aerodynamic, and the metallic particles reflected the sunlight, keeping the gas bags inside
16:05cool.
16:06The combination of chemicals caused problems.
16:09The actual nature of the chemicals were highly reactive, so when the electrical charge did
16:15flow across into the fabric, it caused those chemicals to react, and that's what started
16:20the fire.
16:22With a replica piece of envelope fabric, the theory is easily demonstrated.
16:28You see the sparking?
16:29Right, so that is the aluminium exploding.
16:31That's the reaction of the chemicals in there.
16:35Dr Bain believes that the stormy conditions that night in 1937 had exactly the same effect
16:40on the Hindenburg's dodgy paint job.
16:45Well this new theory fits the pictures and surviving eyewitness accounts.
16:49Once the envelope was alight, the hydrogen fuelled the flames, but it wasn't the cause.
16:56So the Hindenburg disaster was a freak accident, and not the inevitable demise of the airship
17:01as a viable way to travel.
17:04Formed with this knowledge in September 1997, the Zeppelin legend was reborn in southern
17:09Germany with the launch of the first rigid airship for 57 years.
17:14An airship filled with inert helium that has learned the lessons of the past.
17:19The key to the whole design of these new airships is the modern materials used in the envelope.
17:25Basically there are three layers.
17:26An outside layer for UV and weather protection, a middle layer purely for strength, and an
17:32inside layer to seal the gas.
17:34Consequently these airships are much stronger and a lot less leaky than the old Graf Zeppelin
17:39and Hindenburg.
17:42The Zeppelin NT's lightweight structure means more helium is used to lift passengers and
17:46less to lift itself.
17:50And modern engine technology makes this airship both fast and safe to fly.
17:56These engines are 200 horsepower Textron-like combing engines, basically the same sort of
18:01thing you'd find on a small six-seater aircraft.
18:04Now this is tried and tested 1950s piston engine technology, but what's new is that
18:10each engine swivels up about 120 degrees and turns into like a mini-helicopter.
18:16This is what's known as vectored thrust and it's used for take-off and landing.
18:21Flying one of these airships takes a lot of skill.
18:23It's a sort of cross between flying a plane, a helicopter, and a balloon.
18:28Pilots need 1,500 hours of flying other aircraft before they're even accepted on the training
18:32course.
18:34Let's hope they'll make an exception.
18:36I think I'm going to have to have a go at this.
18:47I'm flying this on the stick, which is in my left hand, and I'm heading out towards
18:54the lake.
18:55I've reduced power because once we've taken off in helicopter mode, we've got full thrust,
19:02full forward now in the forward mode.
19:07I'm currently cruising at 80 kilometers per hour at 2,000 feet.
19:12No problems so far, but the hardest task, as with the original Zeppelins, is landing.
19:18Time to go back to helicopter mode.
19:21There is the mast truck looking lonely and waiting for Zeppelin NT-07 to get there.
19:31Just keep it straight ahead of me, using the stick, of course.
19:34I'm coming down on it.
19:35I'm a bit like a stooker at the moment, which is not really what I should be doing.
19:41I'm 115 feet in the air at the moment.
19:46There's the mast truck coming towards me.
19:49We're all in swivel mode now.
19:51I've got to keep it right ahead of me.
19:5361 feet now.
19:56I'm going to smash into the mast truck.
19:59Oh, dear.
20:00Oh, bang.
20:01Smash into the mast truck.
20:04Not very good, really.
20:07In reality, in the hands of properly trained pilots, these new Zeppelins have run daily
20:12tourist cruises over Lake Constance for the last seven years with 100% safety record.
20:21And they've paved the way for airships to start getting massive again.
20:27Armed with a new confidence in safety, here in this hangar, they're taking airships one
20:31step further.
20:32They're getting ready to build airships bigger than the Hindenburg.
20:39This is a working prototype for an airship which will compete with the world's largest
20:43container ships and military transporters.
20:46It's not about luxury air travel.
20:48It's about bulk cargo, faster than ships or trucks, and much cheaper and easier to operate
20:54than the biggest transport planes.
20:56Like the Zeppelin NT, this airship uses tilting propellers.
21:00And the entire structure of the airship is made out of a Kevlar material of various consistencies.
21:06It's light.
21:07It's strong.
21:08It can take down to a bare minimum, which maximises the ship's lifting power.
21:12The full-sized airship, the Skycat, will be ten times the size of the Hindenburg.
21:18The gondola has room for the crew and 30 passengers or fully equipped marines.
21:24But the main load will be slung underneath the gondola, 1,000 tonnes of cargo.
21:29That's 800 saloon cars or 12 80-tonne tanks.
21:34If this airship proves reliable, it has the potential of being a cheaper and faster way
21:38of transporting cargo and military hardware over long distances than ships or trucks,
21:45having the distinct advantages of being able to fly in a straight line from A to B non-stop
21:49and land pretty much anywhere.
21:52But how will such a massive airship survive the unpredictable weather conditions of a
21:56battlefield or a long-distance cargo run?
21:59A really clever bit about this airship is invisible.
22:02It uses fighter-plane computer software to operate the controls.
22:07So to defeat the old enemy, the wind, the computer works at a speed far beyond human
22:12reaction time to keep the airship precisely on course.
22:16Like all its ancestors, the Skycat will be one great big flying engine, an engine that
22:22has taken longer to evolve and has had more setbacks and revivals than any other in history.
22:28The Montgolfier brothers first flew a bunch of farm animals over Paris 220 years ago.
22:33Count Zeppelin pursued a dream of the ultimate flying war machine and the designers of the
22:37Hindenburg turned airships into luxurious flying hotels.
22:43But perhaps at last the airship is about to find its true calling as a giant, graceful
22:49cargo transporter.
22:54One thing's certain though, they're the most massive engines ever.