Why were gliders not invented WAY earlier?

Who were these people?

I’ve read a fair amount about the development of manned heavier-than-air flight without coming across mention of the contribution of hydrodynamics.

Here’s a link to a page featuring a bamboo hang glider.

Yes, and that was one of the things that the Wright Brothers did well.
They made extensive use of their own wind tunnel; they built one over 2 years before the first successful airplane flight, and used it extensively on each successive version of their gliders & planes.

Wel before the Wright brothers, John Stringfellow built a steam-powered (unmanned) propeller-driven monoplane that he flew in 1848

https://en.wikipedia.org/wiki/John_Stringfellow (I had a piece that I wrote on him for Teemings, way back when, but it’s no longer up)
Both Stringfellow and the Wrights relied heavily on the pioneering work of George Cayley, who wrote treatises on flight starting in 1799 (!) and built a working glider I the first decade of the 19th century.

I agree that you’d think that there would be earlier work with gliders. The fact is, there may have been people flying gliders and kites, but we can’t tell fro the accounts if they’re true, legendary, or fiction.:

Perhaps all these tower and cliff jumps were inspired by the vague notion that you had to get clear of the “influence” of the ground in order to fly. :smack: At least Lilienthal had the good sense to test his gliders on a downhill slope.

OK I think by now we can summarize the answer to the original question: Why were gliders not invented WAY earlier?
Answer: They were, just not very good ones. It was not until the late 1880s that understanding of aerodynamic advanced enough to allow people to design and fly decent gliders.

A couple of loose ends:

Yes, failure to understand this was one of the reasons Alexander Graham Bell did not beat the Wright Brothers, despite having a head start and more funding: https://www.thevintagenews.com/2016/06/19/57443-copy-2/

Nobody said Lilienthal, the Wright brothers, nor anyone else got ideas nor designed their machines from hydrodynamics. No one said the early working gliders are like ship’s props.

What was said: “When people started making props for steam powered boats and ships, they noticed some worked better than others. Trying to figure out why and what was the best shape for a prop led to the science of hydrodynamics. People took the discoveries in hydrodynamics and learned variations of the same concepts applied to air flow. Several people sought to apply these new aerodynamic principles to the problem of manned flight.”

The rush to develop bigger and better steam ships in the 1800s lead to advances in hydrodynamics. Several new discoveries in hydrodynamics, like laminar/turbulent flow, also apply to air flow. Because air is compressible and has very low viscosity, and water is (generally) non-compressible and has greater viscosity, people had to learn how principles of water flow are different with air flow. Like the Wright Brothers learning the prop they needed had to be different from a propeller that works well in water. This learning about air is called aerodynamics. And understanding aerodynamics is what allows you to make a successful glider.

It also helps if one’s knowledge of aerodynamics is actually correct. One major thing that prompted the Wrights to build their wind tunnel was much the published data on things like aerofoil shape was flat-out wrong.

And that’s probably another interesting issue. We know to get a running start and take off with airspeed with modern gliders and fixed-wing aircraft. Before the principles were established, one prevalent idea seemed to be that jumping off a tall building was sufficient. However, in the end the same problem killed Lillienthal - unless you have really good control surfaces, it’s difficult to pull out of the resulting dive in enough time, and especially so if you rely on weight shift to change angle of attack - it is ineffective if the glider is too much nose down. Birds could get away with standing starts, but they were far more maneuverable. One of Lillienthal’s biggest break-throughs was taking the running start on a slope.

And as long as the foolhardy jumped off towers and killed themselves, the sensible failed to see value in pursuing that line of experimentation.

Somehow, I’d like to see a cartoon of ancient Egyptian schoolkids throwing papyrus planes in classroom, with the subtitle “Where did all that ancient knowledge go?”

(I bet it’s been done!) :slight_smile:

What people did this?

Based on what they wrote, I’m confident that neither Lilienthal or the Wrights (much the most successful early glider builders) were among them.

You’d probably be interested in the Saqqara Bird a wooden bird model from Egypt, about 2200 years old.

There’s been speculation that this was actually a model airplane, though this seems fanciful - its flying qualities would definitely be most unimpressive.

Yeah, I know about this artifact (mostly from the over-interpretations of von Däniken); but the gist of my joke was that the school-kids’ play might, in the long run, prove more important to mankind than the writ on the torn-out pages…

See, it works on two planes! :slight_smile:

When the Wright brothers first began exhibiting their flyer, onlookers were alarmed to see it bank into turns; they’d imagined it would simply yaw around like a ship making a turn.

And the Sumerian exchange student frustrated trying to fold his clay tablet.

Heck, didn’t the Mythbusters build a concrete glider?

But the most common paper airplane designs are a lot more like a dart than like a glider: The surfaces mostly just provide stabilization, not lift.


That last link is a catapult. It uses bungee cords.

Yes - but it does not depend on anything that could be called modern technology.

Nor does this horse-powered launch.

It very, very much all postdates Lilienthal and the Wrights, so is pretty much moot to the point at argument, but existing research on marine propellers did explicitly feed into Durand and Lesley’s work on designing good aviation ones from 1916 onwards. Chapter 5 of Vincenti’s What Engineers Know and How They Know It: Analytical Studies from Aeronautical History (Johns Hopkins, 1990) goes through that in some detail.

I disagree. there’s nothing complex about glider construction. It could easily be made with animal hide and bamboo or wood. What is necessary is an understanding of the Bernoulli principle. Even without the math behind it a glider can be made through trial and error.