# Why were gliders not invented WAY earlier? **URL:** \ **Category:** Factual Questions\ **Created:** [November 19, 2018, 2:58pm UTC](https://boards.straightdope.com/t/why-were-gliders-not-invented-way-earlier/824790 "2018-11-19T14:58:57Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [November 20, 2018, 2:27am UTC](https://boards.straightdope.com/t/why-were-gliders-not-invented-way-earlier/824790/21 "2018-11-20T02:27:23Z")
> [@LowSignalToNoise](#): > > 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. 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. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [November 20, 2018, 2:33am UTC](https://boards.straightdope.com/t/why-were-gliders-not-invented-way-earlier/824790/22 "2018-11-20T02:33:27Z")
> [@Arkcon](#): > > And I directly question this statement. Bamboo and silk are the lightest, strongest materials available, but they are in no way strong enough to support a human glide. Here’s a link to a page featuring a [bamboo hang glider](https://www.delta-club-82.com/bible/634-hang-glider-bamboo-bomber.htm). ---
**Author:** ![Tim\_T-Bonham.net](https://avatars.discourse-cdn.com/v4/letter/t/46a35a/32.png) [@Tim\_T-Bonham.net](https://boards.straightdope.com/u/Tim_T-Bonham.net)\ **Post date:** [November 20, 2018, 5:39am UTC](https://boards.straightdope.com/t/why-were-gliders-not-invented-way-earlier/824790/23 "2018-11-20T05:39:01Z")
> [@Corry\_El](#): > > … But little changed from 1900 to well past mid century, exactly what shape of prop blade would work best for either ships or planes. It was based on empirical tests. 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. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [November 20, 2018, 1:56pm UTC](https://boards.straightdope.com/t/why-were-gliders-not-invented-way-earlier/824790/24 "2018-11-20T13:56:56Z")
Wel before the Wright brothers, John Stringfellow built a steam-powered (unmanned) propeller-driven monoplane that he flew in 1848 **[John Stringfellow - Wikipedia](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. > **[George Cayley](https://en.wikipedia.org/wiki/George_Cayley)** > > Sir George Cayley, 6th Baronet (27 December 1773 – 15 December 1857) was an English engineer, inventor, and aviator. He is one of the most important people in the history of aeronautics. Many consider him to be the first true scientific aerial investigator and the first person to understand the underlying principles and forces of flight and the first man to create the wire wheel. > In 1799, he set forth the concept of the modern aeroplane as a fixed-wing flying machine with separate systems for... 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.: > [@](#): > > Early pre-modern accounts of flight are in most cases difficult to verify and it is unclear whether each craft was a glider, kite or parachute and to what degree they were truly controllable. Often the event is only recorded a long time after it allegedly took place. A 17th-century account reports an attempt at flight by the 9th-century poet Abbas Ibn Firnas near Cordoba, Spain which ended in heavy back injuries.[3] The monk Eilmer of Malmesbury is reported by William of Malmesbury (c. 1080–1143), a fellow monk and historian, to have flown off the roof of his Abbey in Malmesbury, England, sometime between 1000 and 1010 AD, gliding about 200 metres (220 yd) before crashing and breaking his legs.[4] According to these reports, both used a set of (feathery) wings, and both blamed their crash on the lack of a tail.[5] Hezârfen Ahmed Çelebi is alleged to have flown a glider with eagle-like wings over the Bosphorus strait from the Galata Tower to Üsküdar district in Istanbul around 1630–1632.[ > **[Glider (aircraft)](https://en.wikipedia.org/wiki/Glider_(aircraft))** > > A glider is a fixed-wing aircraft that is supported in flight by the dynamic reaction of the air against its lifting surfaces, and whose free flight does not depend on an engine. Most gliders do not have an engine, although motor-gliders have small engines for extending their flight when necessary by sustaining the altitude (normally a sailplane relies on rising air to maintain altitude) with some being powerful enough to take off by self-launch. > There are a wide variety of types differing in ... > [@](#): > > Eventually some tried to build real flying devices, typically birdlike wings, and attempted to fly by jumping off a tower, hill, or cliff. During this early period physical issues of lift, stability, and control were not understood, and most attempts ended in serious injury or death when the apparatus lacked an effective horizontal tail, or the wings were simply too small. > > In the 1st century AD, Chinese Emperor Wang Mang recruited a specialist scout to be bound with bird feathers; he is claimed to have glided about 100 meters.[1] In 559 AD, Yuan Huangtou is said to have landed safely following an enforced tower jump.[2] > > In the seventeenth century, the Algerian historian Ahmed Mohammed al-Maqqari stated that the Andalusian scientist Abbas ibn Firnas (810–887 A.D.) made a jump in Cordoba, Spain, covering his body with vulture feathers and attaching two wings to his arms.[3][4] No other sources record the event.[3] Writing in the twelfth century, William of Malmesbury stated that the eleventh century Benedictine monk Eilmer of Malmesbury attached wings to his hands and feet and flew a short distance. Beyond those based on William’s account, there are no other known sources documenting Eilmer’s life.[3] > > In 1496, a man named Seccio broke both arms in Nuremberg while attempting flight.[citation needed] In 1507, John Damian strapped on wings covered with chicken feathers and jumped from the walls of Stirling Castle in Scotland, breaking his thigh, later blaming it on not using eagle feathers. > > Similar attempts continued until the early 19th century, with never more than partial success. Francis Willughby’s suggestion, published in 1676, that human legs were more comparable to birds’ wings in strength than arms, had only occasional influence. On 15 May 1793, the Spanish inventor Diego Marín Aguilera jumped with his glider from the highest part of the castle of Coruña del Conde, reaching a height of approximately 5 or 6 m, and gliding for approximately 360 metres. As late as 1811, Albrecht Berblinger constructed an ornithopter and jumped into the Danube at Ulm.[5] > **[Early flying machines](https://en.wikipedia.org/wiki/Early_flying_machines)** > > Early flying machines include all forms of aircraft studied or constructed before the development of the modern aeroplane by 1910. The story of modern flight begins more than a century before the first successful manned aeroplane, and the earliest aircraft thousands of years before. > Some ancient mythologies feature legends of men using flying devices. One of the earliest known is the Greek legend of Daedalus; in Ovid's version, Daedalus fastens feathers together with thread and wax to mimic t... ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [November 20, 2018, 4:46pm UTC](https://boards.straightdope.com/t/why-were-gliders-not-invented-way-earlier/824790/25 "2018-11-20T16:46:57Z")
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. ---
**Author:** ![LowSignalToNoise](https://avatars.discourse-cdn.com/v4/letter/l/ecae2f/32.png) [@LowSignalToNoise](https://boards.straightdope.com/u/LowSignalToNoise)\ **Post date:** [November 20, 2018, 6:04pm UTC](https://boards.straightdope.com/t/why-were-gliders-not-invented-way-earlier/824790/26 "2018-11-20T18:04:43Z")
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: > [@](#): > > Chinese kites were limited because they worked simply by air drag against the wind, and couldn’t glide if not on a rope. 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/](https://www.thevintagenews.com/2016/06/19/57443-copy-2/) > [@](#): > > Lilienthal makes no mention (that I’ve been able to find) of hydrodynamics in his well-known book Birdflight as the Basis of Aviation - the source of his inspiration is given in the title. He definitely wasn’t interested in aircraft propellers - he though flapping flight was clearly the way to go. > > The Wrights intended to use existing hydrodynamic theory in designing the propellers for their 1903 Flyer - but found there basically wasn’t any. At that time ships’ propellers were all designed by rule of thumb, and their best efficiency was around 75% of what the Wrights knew they’d need. > [@](#): > > This was definitely a limitation in adapting one invention from another at that time, that knowledge was so empirical and specific, even though a lot of progress was made that way. IOW ship’s props ca. 1900 were way more advanced than 1840, but with a very limited way of explaining exactly why. > > But the other issue with plane v ship props even to the extent some theoretical comparison was possible, which it was in rough terms, was the pretty different flow regimes of the two cases. Ship’s props are generally constrained to be much smaller area relative the thrust they have to produce, thus they speed up relatively little water by fairly a lot. Airplane props can generally speed up more air by less. That makes the ship prop inherently less efficient on basic momentum principal known at that time, even assuming a completely efficient black box mechanism for speeding up the fluid. It’s still true though that the particular shape of the props’ blades was not determined by theory, in either ship or airplane props. Not even 100% totally now, though more in the last few decades. But little changed from 1900 to well past mid century, exactly what shape of prop blade would work best for either ships or planes. It was based on empirical tests. 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. ---
**Author:** ![garygnu](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/garygnu/32/2924_2.png) [@garygnu](https://boards.straightdope.com/u/garygnu)\ **Post date:** [November 20, 2018, 7:25pm UTC](https://boards.straightdope.com/t/why-were-gliders-not-invented-way-earlier/824790/27 "2018-11-20T19:25:01Z")
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. ---
**Author:** ![md2000](https://avatars.discourse-cdn.com/v4/letter/m/73ab20/32.png) [@md2000](https://boards.straightdope.com/u/md2000)\ **Post date:** [November 21, 2018, 1:39am UTC](https://boards.straightdope.com/t/why-were-gliders-not-invented-way-earlier/824790/28 "2018-11-21T01:39:55Z")
> [@Lumpy](#): > > 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. 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. ---
**Author:** ![Ignotus](https://avatars.discourse-cdn.com/v4/letter/i/ecc23a/32.png) [@Ignotus](https://boards.straightdope.com/u/Ignotus)\ **Post date:** [November 21, 2018, 2:19am UTC](https://boards.straightdope.com/t/why-were-gliders-not-invented-way-earlier/824790/29 "2018-11-21T02:19:32Z")
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!) 🙂 ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [November 21, 2018, 3:49am UTC](https://boards.straightdope.com/t/why-were-gliders-not-invented-way-earlier/824790/30 "2018-11-21T03:49:28Z")
> [@LowSignalToNoise](#): > > 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. 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. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [November 21, 2018, 3:54am UTC](https://boards.straightdope.com/t/why-were-gliders-not-invented-way-earlier/824790/31 "2018-11-21T03:54:45Z")
> [@Ignotus](#): > > 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!) You’d probably be interested in the [Saqqara Bird](https://en.wikipedia.org/wiki/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. ---
**Author:** ![Ignotus](https://avatars.discourse-cdn.com/v4/letter/i/ecc23a/32.png) [@Ignotus](https://boards.straightdope.com/u/Ignotus)\ **Post date:** [November 21, 2018, 6:18am UTC](https://boards.straightdope.com/t/why-were-gliders-not-invented-way-earlier/824790/32 "2018-11-21T06:18:35Z")
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! 🙂 ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [November 23, 2018, 12:14am UTC](https://boards.straightdope.com/t/why-were-gliders-not-invented-way-earlier/824790/33 "2018-11-23T00:14:10Z")
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. ---
**Author:** ![Aquadementia](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aquadementia/32/555_2.png) [@Aquadementia](https://boards.straightdope.com/u/Aquadementia)\ **Post date:** [November 23, 2018, 1:30am UTC](https://boards.straightdope.com/t/why-were-gliders-not-invented-way-earlier/824790/34 "2018-11-23T01:30:30Z")
> [@Ignotus](#): > > 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!) 🙂 And the Sumerian exchange student frustrated trying to fold his clay tablet. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [November 23, 2018, 3:23am UTC](https://boards.straightdope.com/t/why-were-gliders-not-invented-way-earlier/824790/35 "2018-11-23T03:23:20Z")
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. ---
**Author:** ![JKellyMap](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jkellymap/32/15880_2.png) [@JKellyMap](https://boards.straightdope.com/u/JKellyMap)\ **Post date:** [November 23, 2018, 4:32am UTC](https://boards.straightdope.com/t/why-were-gliders-not-invented-way-earlier/824790/36 "2018-11-23T04:32:11Z")
> [@Aquadementia](#): > > And the Sumerian exchange student frustrated trying to fold his clay tablet. 😃 ---
**Author:** ![Irishman](https://avatars.discourse-cdn.com/v4/letter/i/b487fb/32.png) [@Irishman](https://boards.straightdope.com/u/Irishman)\ **Post date:** [November 23, 2018, 3:40pm UTC](https://boards.straightdope.com/t/why-were-gliders-not-invented-way-earlier/824790/37 "2018-11-23T15:40:07Z")
> [@Xema](#): > > You definitely do not need a powered vehicle or a catapult to fly a glider. You can launch off a hill - this is done routinely with hang gliders, and occasionally with [3-axis-control gliders](https://www.youtube.com/watch?v=SwVRLw7TD5I). > > You can also [launch on level ground](https://www.youtube.com/watch?v=w9tE-OWyuK0) (with some help from your friends). That last link is a catapult. It uses bungee cords. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [November 24, 2018, 1:19am UTC](https://boards.straightdope.com/t/why-were-gliders-not-invented-way-earlier/824790/38 "2018-11-24T01:19:26Z")
> [@Irishman](#): > > 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](https://i.pinimg.com/originals/d3/d4/e1/d3d4e1ab327bcb0b612eff5cd80c4d35.jpg). ---
**Author:** ![bonzer](https://avatars.discourse-cdn.com/v4/letter/b/45deac/32.png) [@bonzer](https://boards.straightdope.com/u/bonzer)\ **Post date:** [November 24, 2018, 7:25pm UTC](https://boards.straightdope.com/t/why-were-gliders-not-invented-way-earlier/824790/39 "2018-11-24T19:25:51Z")
> [@Xema](#): > > > [@](#): > > > > 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. > > 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. 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. ---
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [November 24, 2018, 8:01pm UTC](https://boards.straightdope.com/t/why-were-gliders-not-invented-way-earlier/824790/40 "2018-11-24T20:01:42Z")
> [@Machine\_Elf](#): > > Thousands of years ago, people did not have the materials and manufacturing methods necessary to make a strong, lightweight glider capable of carrying a person and being controllable. 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. [Previous page](https://boards.straightdope.com/t/why-were-gliders-not-invented-way-earlier/824790.md?page=1) [Next page](https://boards.straightdope.com/t/why-were-gliders-not-invented-way-earlier/824790.md?page=3)