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Volume 5128
By Rick Johnson
Diagrams by Rick Johnson
Steel ships float because the weight of the water they displace is greater than the weight of the steel plus cargo of the ship.  What this means is that if you take a block of steel one foot on a side, that block will weigh about 490 pounds.  A block of water the same size will weigh about 62 pounds.  Actually, a cubic foot of distilled water at 68 degrees F will weigh about 62.31 pounds.  But weíre not talking rocket science here, we just want to know if the O-220 can fly so weíll use some basic math that we all will understand and round the numbers off.  So a block of steel tossed into the swimming pool will sink!

Actually, that's not really true.   Go to your fridge and pull out a bottle of vinegar-&-water salad dressing.  Notice how the vinegar floats on top of the water?  This is because the vinegar weighs less that the water so floats.  Water, weighing less than steel, floats too.  So the steel isnít really sinking so much as the water is floating on top of the steel.

So steel weighs about eight times as much as water!  What happens if we pound that steel into sheets and form it into a box about two feet on a side?  It will still WEIGH 490 pounds but will now be 8 times as large or cover 8 cubic feet.  Water in a box that size will weigh 496 pounds!  The water will weigh more than the box so the steel box now floats!  Not by much but that's ok.   Pound the steel thinner and make a box 8 feet on a side and it will still weigh 490 pounds but is now cover an area of 512 cubic feet.  Water that size weighs more than 15 tons!  So your steel box can now carry more than 14 tons of cargo and still float on top of the water.

It's all about displacement!

So let us look at displacement airships!

There are two main kinds of aircraft, displacement airships and balloons (aka lighter-than-air) and airplanes and helicopters (aka heavier-than-air).  Airplanes fly by forcing enough air over their wings to create a vacuum above the wing causing the craft to essentially 'fall up'.  So long as the aircraft is moving fast enough, the vacuum is maintained and the craft remains up.  Slow it down to remove that vacuum and it falls! (aka stall-speed)  Helicopters are more like rockets in that they force air down with such force that Newtonís Third Law of Motion takes into effect.  Very loosely, it means that you exert a force upon an object and that object exerts an equal force upon you.  Throw a ball and that ball also throws you back.  You donít notice it because you weigh so much more that your inertia prevents any real opposing force.  But stand on a skateboard and throw that ball!  But we really donít care about this unless we are examining Barsoomian airships.  So letís forget this paragraph and move back to displacement airships, and weíll focus on the Hindenburg simply as being the most famous and largest airship made.

The Hindenburg, aka LZ-129, was possibly the largest and most famous of
the lighter-than-air craft built even though it lived barely more than a single year.
Length  803' or 245m
Diameter 135' or 41m
 Weight  215 tons (total weight if you put it on a scale)
 Displacement 232 tons  (weight of the air that would fill a Hindenburg-sized hole)
 Speed  85 mph or 135 kph
 Crew  40-61
 Passengers 50-72

Here's a pic of it for scale.

The thing is freaking BIG!  See that little blue fish under the Titanic?  It ainít a goldfish, that is a Blue Whale!

All that size and weight just to move maybe 100-150 people across the ocean?  Why?

Well, remember that paragraph I told you to forget?  Remember it now.  Back in the days of the Airships, propeller-driven aircraft had neither range nor size to cross the Atlantic safely.  They could, but required multiple refueling stops and were so small that they couldnít carry many passengers.  When I flew across the Pacific in the late 50ís, federal law required four engines and we still had to refuel at every opportunity.  See that 747 above the thing?  Passenger aircraft back then were less than half that size.  Airships were the only aircraft with the necessary range that could safely cross the Atlantic!  Ok, the Hindenburg blew up, but only after making 63 completely safe flights.  And the final flight is mired in conspiracy concerning sabotage!  Really, look at the politics of the time and ask yourself if one (unnamed) nation would be willing to destroy that German Airship and kill all those people just to prove that they (German airships) were unsafe!  Was it an accident or not?  I donít know.  I DO know that the Hindenburg was built with British dura-aluminum and designed to fly with Helium but the US refused to sell the LZ company that much safer gas, forcing them to redesign the craft to carry the much more dangerous hydrogen.

Although I am unable to find the total volume of the Hindenburg, some very rough calculations gives me a maximum volume of 5,749,690 cubic feet.   Air weighs (at sea level) 0.0807 pounds per cubic foot.  Multiply that by 5.7 million and you get 464,000 pounds = 232 tons of air.  The total amount of air that the Hindenburg would displace is 232 tons.  Thus to floats above the air as a cork floats above water.  The idea is to replace as much of the air INSIDE the Hindenburg with something that is much lighter than air, and that is all those fantastically huge bags of hydrogen gas which weighs in at 0.053 pounds per cubic foot then compare that to the weight of the bags when filled with air, you end up with 232 tons of lift!  As the Hindenburg weighed only 215 tons, you have a very comfortable safety range of 17 tons.


Modern airships use the much safer Helium which weighs four times as much as hydrogen but is still half the weight of air so they fly, but must be lighter than before to do so.  Modern blimps reduce weight by removing the metal skeleton to reduce weight and increase lift.  Even then they must displace a fantastic amount of air to even lift.  Airships MUST be huge to lift the weight of the ship and the people.  Look at a hot-air balloon!  They use a wicker basket to reduce weight and still are fantastically huge.


But what about the O-220?  It doesnít use Hydrogen or Helium, it uses, nothing! The inside of that craft is empty!  Not, my closet is empty empty, more like space is empty empty.  The kind of emptiness that will suck  your lungs from your body and freeze-dry your blood at 1000 degrees F empty!  Hmmm, does this mean that despite our attempts to simplify matters, Vacuum airships are simply a figment of our imaginations?  It turns out that the math is simple and works.  Yes, the Vacuum airship, aka O-220 IS possible so why donít they exist?

Bit-o-trivia here.  Francisco Lana de Terzi first explored the idea of a vacuum airship back in 1670.  His plan didnít work, of course.  He was too bogged down in the water-boat concept (watch the 2011 Three Musketeers film to see galleons flying via hot air balloons for this) and the technology of the time prevented neither a decent vacuum or materials light enough and strong enough to support a vacuum.
Given in United States Units
215 tons
75 tons
232 tons
225 tons
85 mph
105 mph
CREW and 
Tarzan, Gridley, 
crew, WaziriÖ. 


As you can see from the brown overlap that the O-220 is a bit thicker but much longer than the Hindenburg, yet is almost 1/3 the weight.  It's longer than the Titanic!  It has to be!

Did you ever watch a science teacher attach a hose to a steel can, then suck the air out?  That steel can crumples like an empty beer can against a redneckís forehead.  And THAT is the problem with a vacuum airship.  We do not have any materials strong enough to support that pressure.  Consider that the air at sea level is pushing in at 14 ½ pounds per square inch.  Remember that steel box with each side being one inch?  Do the math.  14.5 x 6 = 87 pounds.  Make that box 4 times larger but keep the same weight and you have it 1/8th the thickness but the air pressure jumps to 348 pounds. Make it larger againÖ eventually you will have something thinner than paper but trying to support tons of air pressure.  Look at it like this.  Have a 140 pound woman walk across a wet lawn in her bare feet.  No problem.  Then have her put on stiletto heels and sheíll sink to her heels in the lawn!  Same basic principle.  Sit on a balloon and no problem, poke it with a needle and you destroy the balloon with less pressure.  Air is like that needle, only all over the thing!  A steel box large enough to resist 14.5psi will be too heavy to displace the required volume of air.  A steel box thin enough to be lighter than the air is too fragile to support  that pressure.  Aluminum is worse.

We simply do not have ANYTHING light enough and strong enough to make a vacuum airship that can resist that much air pressure!  Birds are experts on reducing weight.  They abandoned teeth and jaws for a lighter beak. They made their bones hollow then added internal rods to support that fragile system.  They even dump ballast upon take-off (which means that they poop when they lift) to loose every possible ounce.   And even then, there are limits.  The California condor is the largest flying bird alive and it is so fragile (to save weight) that it dares not attack anything larger or meaner than a puppy.  A child can punch a hole through a Condor's body.

So remember that crumpled steel can?  Consider how many vacuum containers are within the O-220 (6) and how large they are and do the math.  If normal air pressure can crush a steel can that resists the efforts of a grown strongman, what can it do to a vacuum airship?  And 90-95% of that airship MUST be empty wasted space to contain the massively huge vacuum chambers.

Vacuum Airships are like that!  Were the Hindenberg to be a Vacuum Airship instead of a Hydrogen Airship, instead of weighing 242 tons PLUS 18.7 tons of hydrogen = 260 tons total, the Hindenburg would weigh only 242 tons!  You could carry almost 19 tons of cargo or people or .. books and chocolate!  Instead of a crew * passengers of 80, you could carry an extra 200 passengers @ $?? Per person profit!

So the secret to the O-220 is the extreme lightness of the materials used in the construction of the airship.  Harbenite, found in the Valley of the Lost Legion MUST be so light it almost floats away, yet so strong that a sheet thinner than paper would deflect a bullet!  Even then, the internal vacuum tanks must have rods to hold the sides of the tank apart.  Iím thinking of some metallic composit that forms in a hollow crystalline shape similar to how water forms a hollow crystal when it freezes to become lighter than liquid water.

The hull of the O-220 must be paper thin, the girders must be pierced I-beams and restricted to critical areas.  Weight MUST be carefully calculated and, well, were the O-220 to be crushed to a single block, it would still weigh 75 tons but be a block slightly larger than 14 feet on a side.  Air weighs 0.08 pounds per square foot. The total volume of the O-220 is about 17,485,875 cubic feet (aprox, I had to fudge by estimating the curvature of the airship).  That volume of air weighs 225 tons!  Since the O-220 only weighs 75 tons, Harbenite must weigh about 57 pounds per cubic foot.

Here are a few stats for various materials per cubic foot:
-Cypress wood is 30 #
-chestnut wood is 41#
-Leather is 59#
-concrete is 70#
-water is 62#
-ice runs from 54 to 56#
So Harbenite is heavier than wood but lighter than water.  A block of Harbenite will float in water!  I donít know enough chemistry to know what metallic composition is that strong and light but we can shove a space-station into orbit with a bottle rocket with that stuff!

Is the O-220 possible!
With today.s materials, no.
We NEED Harbenite to make it work.  And even then, the airship must be freaking HUGE and mostly vacuum tanks to lift.

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