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Owls and vortices


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Guest Machtuk

I giggled at the ref to "toy plane" the RC lovers get their noses out of joint when their models are ref to as "toy planes"? The very early days of pioneering flight watching the birds & experimenting must have been both exciting & frustrating. Oddly enough the planes of today use the same principle as the 'Wrong Bros' did all those years ago & they still crash the same?

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Very interesting video. Main thing I took from it was the very small vortices from the owl in glide mode - incredibly efficient. Presumably that's why their flight is so quiet.

 

As an aside, I've often wondered why birds don't have any trace of a vertical tail surface. Fitting a fin to early flying machines was a stroke of genius by whoever first did it.

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Soleair it's my understanding that the silent flight of owls is due to some special feather arrangement they have:

 

https://www.audubon.org/news/the-silent-flight-owls-explained

 

>“Owls have a suite of unique wing and feather features that enable them to reduce locomotion-induced sound,” says Krista Le Piane, a graduate student at the University of California, Riverside who recently presented her work on the evolution of silent owl flight at the Animal Behaviour Society conference in Ontario, Canada. They have large wings relative to their body mass, which let them fly unusually slowly—as slowly as two mph for a large species like the Barn Owl—by gliding noiselessly with little flapping. Additionally, the structure of their feathers serves as a silencer. Comb-like serrations on the leading edge of wing feathers break up the turbulent air that typically creates a swooshing sound. Those smaller streams of air are further dampened by a velvety texture unique to owl feathers and by a soft fringe on a wing's trailing edge. These structures together streamline the air flow and absorb the sound produced.

 

As for the tail fin, most birds are able to twist their lower body, so tilting the 'stabiliser' of their tail feathers to the left or right.

This is easiest seen in large birds water birds when they are landing.

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The next quantum leap in aviation efficiency will happen when we develop man-made, larger versions of wing feathers, individually controlled by flight computers.

Interesting idea. I recently saw this Mercedes AVTR concept car that uses individual aero surfaces controlled by computer.

 

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Guest Machtuk

Flight will have no significant change in what we have today in our lifetime or even the next few generations. Automation & efficiency are the only areas that can be sought out for improvement in a practical way. EP flight for Eg on a commercial level is simply Jules Verne stuff!

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The big barrier is going above Sonic. Cruise speeds haven't really changed for commercial jets for over 40 years. Fuel efficiency is all that's changed and flying a bit higher. Larger planes ( A -380) are efficient because of scale effect but hard to fill, so size wise and speed wise we are stuck. Faster will be a lot more expensive. We've tried that and sub orbital also expensive. Squeezing people in is profitable and unpleasant. Fares are as cheap as they will ever be. It's only UP from here on. I would NOT invest in anything to do with Airlines or making CARS. Nev

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Flight will have no significant change in what we have today in our lifetime or even the next few generations...

 

Sounds like a lot of brave, but famously wrong predictions.

 

In the late 19th century it was predicted that the US Patent Office would soon have to close down, because all the inventions had already been made.

IBM thought there was a world market for a dozen or so computers.

Bob Menzies couldn't see any future in computers (Australia built the world's fourth mainframe whle he was PM- it's still intact and now the world's oldest). Menzies couldn't see any future in space even through Australia was a pioneer...

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Guest Machtuk

....

Sounds like a lot of brave, but famously wrong predictions.

 

In the late 19th century it was predicted that the US Patent Office would soon have to close down, because all the inventions had already been made.

IBM thought there was a world market for a dozen or so computers.

Bob Menzies couldn't see any future in computers (Australia built the world's fourth mainframe whle he was PM- it's still intact and now the world's oldest). Menzies couldn't see any future in space even through Australia was a pioneer...

 

oh and all the above means my beliefs are wrong? Hello anybody home there??

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One has to be careful when making future predictions, because when one is doing so, one can be completely blindsided by technological advances that come out of left field, which technological advances can be quite revolutionary.

 

I have a copy of the (American) Peoples Almanac from 1975, and it has an entire chapter devoted to future predictions (going past year 2000) by acclaimed seers, scientists, engineers, religious leaders, and many industry leaders.

It's quite amusing to read now, how the vast majority of these "experts" got all their predictions seriously wrong. Only one person predicted something similar to the Internet, to be in operation by year 2000.

Not one of them foresaw the collapse of Eastern Bloc Communism, none predicted or foresaw the pulling down of the Berlin Wall and the re-unification of Germany.

Many forecast personal flight vehicles, none of which has come to pass. Numerous predictions saw world wars between China and the U.S., or Russia and the U.S. in the 1990's and early 2000's.

Only one forecaster predicted Chinas rapid rise to a global power in the 1990's to early 2000's period. Not one predicted the rise of battery power for energy, and not one predicted the invention and universal use of smartphones.

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It's actually a continuation of a LONG stagnation period. Its economics. The boundaries have been prodded and found solid and resistant. Boeings SST failed metallurgically the A 380 is going out of production. Boeings shot itself in the foot with cost cutting and QA. We will see if the Carbon Dreamliner is good enough in the field. Fuel availability presents a big challenge with environmental s being an issue. WHO will invest? Aviation has ALWAYS been shaky and long runs of good returns just don't happen, and really never have. Governments Underwrite a lot of airlines. Producing big Turbo fan engines has nearly sent Countries broke. A virus can/will send Airlines to the wall. They have high cash flows with small profit margins. A fuel price hike or a drop in load factors and you are losing BIG money every hour you fly. Nev

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The number of major, earth-shattering technological inventions, that make for great leaps forward in design and cheaper/smoother/faster operation, are continually reducing.

I put this down to the limits on available money and the lack of pressure for new inventions. In WW2, money was thrown at inventions, improvements, testing, research, and new materials - and the pressure to find them, to win WW2, was intense.

But today, the improvements are only incremental, money in large quantities for research, development and new materials is in short supply, and there is no pressure to improve on what is already regarded as being satisfactory and "cutting edge".

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Sounds like a lot of brave, but famously wrong predictions.

 

In the late 19th century it was predicted that the US Patent Office would soon have to close down, because all the inventions had already been made.

IBM thought there was a world market for a dozen or so computers.

Bob Menzies couldn't see any future in computers (Australia built the world's fourth mainframe whle he was PM- it's still intact and now the world's oldest). Menzies couldn't see any future in space even through Australia was a pioneer...

I've been saying we need a battery break-through to make EVs feasible and that has been trotted out against me many times. There is even a long list of famous last words which circulates from time to time, so you do take a risk if you kill the chance of a new invention.....but I've been waiting 34 years for a battery that meets my specification.

 

The thing that happens is that as fast as new inventions come along knowledge is lost to the human race. About 20 years ago I remember how Alan Ramsey, Workshop Manager for Mayne Nickless Ltd diagnosed steering wander in a Prime Mover, requiring an additional chassis crossmember using four buckets of water and two broomsticks.

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I think the fixed number of elements on the periodic table and the laws of physics are the limiting factors more so than money. Every possible combination of metals and oxides must have been tested for their battery potential by now. The eventual use of two very successful products of recent times Glyphosate and Viagra were discovered by accident.

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That would be ominous for civilization, OT.

We have a developing crisis with antibiotic-resistant super-bugs, as pharmaceutical companies spend less on developing new antibiotics, preferring to maximise profits by pushing up prices for existing drugs.

 

Given the forces currently affecting global trade, the economic forces driving innovation may be easing off. It's conceivable that we might be entering an era of technological stagnation which would require some painful adjustments.

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The number of major, earth-shattering technological inventions, that make for great leaps forward in design and cheaper/smoother/faster operation, are continually reducing.

I put this down to the limits on available money and the lack of pressure for new inventions. In WW2, money was thrown at inventions, improvements, testing, research, and new materials - and the pressure to find them, to win WW2, was intense.

But today, the improvements are only incremental, money in large quantities for research, development and new materials is in short supply, and there is no pressure to improve on what is already regarded as being satisfactory and "cutting edge".

Not to mention regulation as a development killer.

I read an article a few months ago that discussing how new innovation in highly regulated areas such as aviation and medicine were in serious decline based on the significant decrease in the numbers of patents whereas the less regulated IT industry has been moving extremely fast with many new innovations.

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the premise being both are lifting surfaces (tail/wing) ... isn’t that what is behind canards, specifically the Quickie or Dragonfly. Both surfaces lift and as a consequence you have less drag and imo, a much smoother flight in turbulent air (through thermals).

 

so we already do this...and it works

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The next quantum leap in aviation efficiency will happen when we develop man-made, larger versions of wing feathers, individually controlled by flight computers.

 

Getting back to this, I can see it becoming more common in motorsport, like the Mercedes AVTR concept, and then maybe military aircraft.

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Getting back to this, I can see it becoming more common in motorsport, like the Mercedes AVTR concept, and then maybe military aircraft.

Maybe with the right technology we could do it, but it's not new. They've been working on variable geometry for years, decades even. They've tried to make flexible wing surfaces to change camber and wing area, but ended up with fowler flaps and slats and a swing wing such as the F-111 and F-14. eventually those were scrapped and we returned to simpler airfoils of better design.

 

I have wondered if anyone might use a variation of the idea for helicopter rotor blades though. Having blades which change geometry to control the aircraft instead of airframe mounted servos through a swashplate and PCRs. Such a machine could track and balance the head automatically instead a series of adjustments on the ground that have to suit all flight regimes.

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