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Comment by rootusrootus | Hacker News Reader

Given how straightforward the physics are, what is the limiting factor that kept us from developing planes sooner? Insufficient propulsion power to overcome the drag of an inefficient wing?

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Almost none of this is intuitive without hundreds of years of hindsight. The more subtle aspects of stability, such as avoiding oscillation mostly had to be determined experimentally. Then there is also the matter of actually constructing a plane, if you want it to be useful, it's going to need to be a lot more then some folded paper.

Thrust was definitely also a problem, a glider is not particularly useful unless it has a huge lift-to-drag ratio, which is only possible with modern materials and a solid understanding of airfoil design, which is a whole other can of worms.

Even things that seem so basic that we don't even think about them, like high were not at all obvious: just look at Sir George Cayley's gliders.

Paper planes have been a thing for a long while, but I guess no one thought that could scale?

It's like fire, super obvious in retrospective, and yet took thousands of years to become a technology.

It’s not easy to scale materials and retain the necessary rigidity. Like if you tried to scale up a primitive kite to support a human it would either be too heavy or too bendy. You need better materials and better construction techniques.

>Paper planes have been a thing for a long while, but I guess no one thought that could scale?

... and they were right, because aerodynamics is not scale-invariant.

Well, airplanes do exist now, so that did definitely scale.

Airplanes were developed almost as soon as piston engines became available. Steam engines were too heavy for a plane. And even the early piston engine had a bad power/weight ratio. For french speakers, there is a video of a retired Dassault plane designer where he mentions (among other things) that developments in plane design basically followed developments in engines.

https://www.youtube.com/watch?v=lu4V9zn0wZ4

Also highly recommend his previous video about the design of the Rafale, it's basically a lecture in plane aerodynamics.

https://www.youtube.com/watch?v=XrpsptSLt90

Leonardo Da Vinci lacked good propulsion. But otherwise people have been toying with replicas of his designs and getting them to fly. Compact, petrol engines did not emerge until late 19th century. And they weren't very light. So, that was indeed a factor. Putting a steam engine on a plane was not going to fly.

Though, they might have invented some kind of functional glider and used a steam powered winch. But, I'm guessing the aero-dynamics weren't that widely understood yet. And making stiff lightweight air-frames also took some time to happen. The contraption that the Wright brothers flew was a bit flimsy. And it barely flew. It was more of a proof of concept. Things like thermals and other updrafts that make gliders work weren't that well studied probably.

Control was an almost completely unaddressed issue before the Wrights took it up, even though it is also crucial to useful glider development.

This video has a nice delineation of the collection of breakthroughs needed:

  https://youtu.be/EkpQAGQiv4Q?t=391

Yes. AIUI, as bicycle riders the Wright brothers understood the need for banking in turns rather than thinking of maintaining a constant roll orientation throughout a turn

Basically, understanding airfoils. Back in the 1840s they put miniature steam engines in model planes and got them to fly. There were powered ground-effect planes in the 1800s that had more powerful engines than the Wright Flyer, but the Wrights were the first people to invent the wind tunnel, so they had a better understanding of lift-to-drag and control surface issues. They adapted the flow-pattern analysis tanks used by ship designers.

As mcarmichael said https://youtu.be/EkpQAGQiv4Q?t=391

The basics are straightforward while having the hindsight of all the development we have enjoyed in the last hundred years. Stable flight was a hard nugget to crack. Better mechanical design, understanding of fluid dynamics, lighter materials, engines with higher power-to-weight ratios, etc all brought us to where we are today once the Wright Flyer was demonstrated.

My understanding is that it wasn’t power-to-drag but power -to-weight.

Although the Wright brothers deservedly get a lot of credit, I think they made progress once they enlisted the help of Curtis due to his knowledge of lightweight internal combustion engines.

The book Bird Men is a god read on this subject.

> The book Bird Men is a god read on this subject.

Thanks for that recommendation, I'll add that to my book reading list!

For anyone who has trouble finding this book like I did, the actual title is Birdmen (no space):

https://www.amazon.com/dp/B00GL3MGTI

Weight. A typical steam train has enough propulsion power to overcome an enormous amount drag, but its power-to-weight ratio is low.

Yes, the wright flyer came fairly soon after internal combustion engines became light enough.

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