Why did it take us so long to invent flying in balloons?

Factual Questions
21

That’s a good point, but scaling the envelope was also nontrivial. I’d argue that doing so was infeasible prior to the appearance of cheap, strong, consistent paper. I don’t think it’s a coincidence that practical human-scale balloon flight first appeared around the time of the industrial revolution.

Balloon flight at any scale requires materials with uncommonly good strength-to-weight ratios. Beyond silk, I can’t think of a natural material in the right ballpark. Even then, in a world without balloons, it’s not obvious that any silk bag full of air could ever lift itself (no matter how hot the contents).

Paper was the first practical material for balloon envelopes that I’m aware of. The Chinese, who had plenty of silk, made most of their balloons from paper (AFAIK). The Montgolfier brothers started out with taffeta, but moved to paper almost immediately—and didn’t look back.

I’d argue that the appearance of large-scale ballooning depended upon on paper manufacturing at an industrial scale. Without that, there was no known material strong enough—I mean consistently strong enough—to pull it off.

Prior to the invention of synthetic polymers, balloons were a lot more challenging from a materials science perspective than contemporary heavier-than-air machines. Aside from paper and silk, we had almost no thin, strong fibers or films until after WWII.

The Germans didn’t build the Hindenburg out of cow guts, hydrogen*, cellulose and thermite because they were quirky or unaware of how fire works. There were simply no other options.

  • I know—the Germans used hydrogen because the Americans wouldn’t sell them helium. But helium is less buoyant than hydrogen and only exacerbates the strength-to-weight problem.
22

Years from now people will be asking why it took so long for robot servants to be put into everyone’s homes, when robot toys (programmable and/or voice command) were around for so long.

23

Remember 2 things - industrialization and technology. yes, the ancients had paper- but until it was being made by machines in industrial quantities, every square yard was made by hand. If the merchant was lucky, he had water power to help some of the heavy lifting. Ditto for cloth - look at a decent sized Mongolfier balloon, there’s enough paper to keep a monastery going for a year, and enough cloth to cover a small village. Not to mention hundreds of feet of ropes… Also - all this stuff weighs something. Industrial machine works can consistently make reliable rope, or paper, or cloth, strong yet light enough in quantity. Burner? Need a lightweight metal bucket that can hold a fire - until modern metallurgy, producing things like sheet steel was very difficult and expensive.

Sails are a bad counterexample - they had to be heavy to stand up to squalls and gusts without tearing. A balloon probably uses the thinner, much lighter fabric - the sort that was at a premium for women’s fancy dresses. (i.e. expensive)

The issue is we tend to forget the cascade effect of the growing industrial revolution in Europe. When everything had to be made and moved by hand or beast of burden, items were relatively expensive. To make iron, once you’ve denuded the countryside, requires coal. Unless you and the coal mine are on a fortuitous waterway, the best that can be done is to cut coal by hand, haul out of the mine by pulley, haul it by cartload and hope the oxen can get the loaded cart through the mud ruts if it recently rained… ditto for the iron ore. The bellows were operated by hand, and the hammers for beating the iron… etc. In middle ages and earlier, metal was precious - all those Greek ruins have pits in the pillars where locals dug out the lead anchors that held the drums together, once adult supervision disappeared during times of strife… heck, people still steal any copper not nailed down, and much that was.

the other problem alluded to - when everything was done by hand, slaves were the “hands”. Thus any physical practical work was looked down on as menial and beneath a thinking intellectual. So a Brainiac of the Roman empire would probably ask his slaves to make something like that, and odds are the slaves would not grasp the nuances of making a practical device. (Or didn’t care, or were happy to build something badly that might kill the master.) To top that off, practicality reigns. What good is a hot air balloon? The Mongolfiers were just having fun. If the balloon carried you twenty miles away, someone had to follow in a cart (or several) to collect the balloon and haul it back - it didn’t automatically return. A tethered balloon has to lift a spool of rope that lets it float above arrow range, if you’re going to use it as a shooting platform (and enough ammunition to make a difference, and hope the base doesn’t get overrun while you’re up there…)

Similarly iron boats - what good are they until you have to defend against canon? And canon in the first few years were liable to blow up until the metallurgy caught up with the need. Again, making enough iron to build a decent sized ship requires industrial technology. And rivet or welding technology. Similarly for steam engines. The early days of steam are full of stories of badly made boilers and bursting vessels or pipes. Before giant foundries and mass production, consistent quality metal was always an issue - and it was too expensive to fiddle with for fun. The evolution of mechanization follows a predictable path of response to real need resulting in refined or new devices. Necessity, not tinkering, is the mother of invention.

(I had a discussion with a history prof who offered a “History an technology” course years ago. Romans didn’t put big catapults on warships because the recoil would twist the spine of the ship, loosen the planking so it leaks, etc. It just didn’t work. Firing down the length of the ship interfered with the rigging that held up the mast, and severely limited your aim, especially if you were trying to aim into the wind. Plus, you had to carry a lot of big rocks, which slowed you down for maneuvering.)

24

Helium is less buoyant than hydrogen, but not by very much. The important point is that either one is a small percentage of the density of air. On the other hand, hydrogen isn’t actually all that dangerous as a lifting gas, and it’s a fair bit cheaper than helium.

25

I don’t see this as a valid analogy. Robots (as far as we know) are a complicated technology. Balloons are not. You can explain how a balloon works to a preschooler.

26

I think you might be on to something, but I’d speculate that this isn’t a characteristic of particular cultures, but usually a manifestation of individual insecurity.

Nearly every time I hear something dismissed as a “toy,” the speaker is a blustery man who’s out of his technical depth.

I design scientific instruments for work; I’m also an amateur photographer. Some inexpensive lenses happen to have extraordinary optical quality, and I routinely hear amateur men (almost never women or working professionals of any stripe) dismiss those lenses as “just toys.”

You can make a heck of a scientific instrument out of a sewing needle and a buzzer from a broken smoke detector: an atomic force microscope, which is a really useful addition to any home nanotech research lab.

Technically competent people value result/data quality above almost all else. When the results are solid, dismissing the instruments as “toys” isn’t a great look. It implies that the speaker doesn’t understand what he’s looking at.

Sure, each society has cultural biases that can play a big role in which technologies it adopts. And while this can create dangerous blind spots, they tend not to last long.

There’s a long tradition of seeking out and exploiting technological blind spots. The Greeks fooled the famously martial Trojans by exploiting their preconceptions about what’s a threat and what isn’t.

Hint: not all weapons are sculptures, and not all sculptures are weapons. But some sculptures are definitely weapons. Especially the big, horsey kind.

27

Great post, md2000!

A few notes:

Sails - the point was that the width of a loom of was not a factor.

Coppicing was a sustainable method of harvesting wood indefinitely without denuding the countryside, widely used for many centuries.

Wood could be used to make charcoal. Charcoal burners still worked in parts of England well into the 20th century, making charcoal in small-scale operations in the traditional way. The charcoal was used in smelting furnaces, by blacksmiths, etc.

That depends what you mean by catapults. They didn’t use trebuchet-type stone throwers or onagers on ships, but they did use large bolt-firing catapults (ballistae). These could also be used to fire small stones with great force and accuracy.

28

But you don’t need metallurgy to make a balloon. You can make a balloon out of silk. And silk production is a technology so old it predates writing.

29

This. Even if conceived of in prior times the cost would have been too high. There must have been numerous times people somehow got a small bag of cloth or paper into the air over an existing fire, and even conceived of the bag large enough to carry a person and a flame aloft, but it required wealth and technical prowess to carry that concept through experimentation and into reality, and the Montgolfiers were blessed with both.

30

Smoke holes were used before chimneys, and also require the (fairly obvious) concept that smoke rises.

To what extent this leads to the conclusion that warm air rises whether or not smoke is involved may be uncertain*; but I doubt the difference has much to do with chimneys in particular. Anybody who’s ever looked at a fire knows that smoke rises.

31

Balloons are only simple when it comes to basic lift. When it comes to manufacturing in the pre-industrial era, nothing was simple. The principles of the steam engine are very simple as well, and we had demonstrated steam’s ability to do work when the aeolipile was developed in Egypt in the first century. But it took a thousand years for the first steam-powered device, which was an organ. Many inventors including Leonardo Da Vinci talked about steam turbines, steam cannons and all sorts of steam devices, but it wasn’t until 1698 that the first practical steam engine was developed.

To get there we needed advances in metallurgy, thermodynamic science, understanding of pressure and work, pistons, vacuum, yada yada. But we also needed precision machining and repeatable processes, which are fairly recent innovations.

32

Oh, absolutely. We fully agree about all of this. I mentioned it partly to illustrate extreme and less-than obvious requirements demanded of balloon envelope materials.

That said, hydrogen offers about 8% more lifting capacity than helium. You can fly an airship filled with either, of course; the technology was sufficiently advanced by the time dirigibles showed up. 8% more lifting power is a lot like having 8% less weight to lift, and that would be a huge deal even now. The margins have always been tiny.

I mention the difference only because I think it helps illustrate my answer to the original question. Nonexistent or tiny material margins are part of the reason we didn’t see human-lifting balloons earlier than we did.

33

Silk has great material properties, but translating those numbers into a practical gas bag is harder than you might appreciate.

As I said earlier, the Chinese had access to both and overwhelmingly used paper for their balloons. Silk isn’t the slam-dunk you seem to think it is.

34

I doubt very much that you can explain how to construct a proper burner used in a balloon vehicle. It’s not a camp fire in a basket.

Even the concept of heat making things rise is not something intuitive to people, let alone children. You could demonstrate it, but there’s a difference between showing that something works and explaining how it works.

My point wasn’t that balloons are robots. My point is that people estimate how difficult it is to scale up from a toy. An example made in this thread is a wheeled toy used by cultures that don’t use carts. A cart needs to be made of materials sturdy enough to bear weight but light enough to push with minimal effort. You need a flat, level surface (roads) to move it any appreciable distance. How do you keep it from falling apart when it jounces around with a lot of weight in it? These are things that people needed to figure out in order to implement something we might take for granted as simple.

35

Nazca Lines & the World’s First Hot Air Balloon: A Theory of Ancient Flight in Peru & Nazca Desert Mystery

36

You don’t need to fly to see the Nazca lines. Up on the nearby mountainside will serve just fine.

And “not as outlandish as von Däniken” isn’t saying much.

37

Indeed, the Montgolfier brothers, the ones who were to ballooning what the Wright brothers were to airplanes, initially thought it was SMOKE that caused the balloons to rise.

It takes an enormous amount of hot air to get even one person off the ground and prior attempts just didn’t use a big enough balloon. Much like early attempts at fixed-wing flight typically just didn’t have enough wing area to generate the lift needed to glide, much less actually fly.

38

I agree this is true for a steam engine or a robot. But a balloon is not a steam engine or a robot. In terms of complexity, a balloon is comparable to a ladder or a chair. It doesn’t have any moving parts and if you get it only ninety percent right, it’ll still do the job.

39

I understand why we didn’t have hydrogen or helium balloon earlier than we did. But I was asking about hot air balloons.

40

Clearly the ancient astronauts were landing their spacecraft on the nearby mountainside. Thank you for that clarification Chronos.