Umboi: Did Rays Evolve The Ability To Fly?

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common_sense_seeker said:
For the cryptozoologically minded, here's a related thread: Springheel Jack & The Jersey Devil.
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That just makes you look even more bloody crazy.

1) You make a claim about ocean dwelling rays which has no evidence and is contradicted by basic anatomy and aerodynamics. You claim to have worked in aeronautics but show no understanding of it.

2) You are obsessed with mythical creatures, citing heresay and rumour as 'evidence' and suggest detection methods which are utterly impractical (ie the satellite photos)

3) You then make claims these unobserved mythical creatures are descended from your unobserved flying rays, despite having neither animal to examine, no evidence either exists, no evidence they have existed and no fossil records of their evolution.

You mount assumption on guess on random idea on unsupported views. And you do the same when it comes to your attempts at science, you have absolutely no clue how science is done.

I am absolutely certain you have lied about having a degree in a science based subject and your career in aeronautics. You lack basic common sense (which makes your name ironic), never mind a firm grasp of the scientific method and practical understanding of a quantitative area like aeronautics.
 
AlphaNumeric said:
I am absolutely certain you have lied about having a degree in a science based subject and your career in aeronautics.
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What? He claims to have a degree? To have worked in aeronautics? Oh dear, I just re-read the thread, he claims to 'have a distinction' in aeronautics, but then comes up with crap like this;

commonsenseseeker said:
You obviously haven't ANY knowledge of aerodynamics; a flying wing shape can provide just as much lift as long slender wings. The weight aspect is often a red-herring that novices can't see past.
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Which shows an utter ignorance of this;

fourforces.jpg


Weight isn't something 'novices can't see past' it's one of the fundamental aspects of aircraft design.
 
phlogistician said:
What? He claims to have a degree? To have worked in aeronautics?Oh dear, I just re-read the thread, he claims to 'have a distinction' in aeronautics
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I thought he said it was astronomy and then went on to work in aeronautics. The fact he later then said Newtonian and Einsteinian gravity don't account for the directional nature of gravity seemed to stick a fork in his claim he has ever done astronomy.

Claims to have got 98% in his 1st year and to be a 'simulation modeller'.

Claim of a degree in astronomy and computing.

Repeats claim of astronomy and computing degree and having won an award for being top

Claims a distinction in aeronautics

So which is it, aeronautics or astronomy & computing, CSS? And where did you go to university? If you were the top person out of 300 then you must have gone to a terrible university, utterly utterly terrible.
 
OK, he's definitely talking out of his anus, because the simple numbers rule out his stupid claims, and he's clearly not scratched the surface of a quantitative investigation of his stupid pipe dream.

Let's revisit the numbers, an Albatross (which he uses an an example of an bird that can soar using minimal energy) has a wingspan of around 3m, and weighs about 20kilos. If we scale that up to the size of the 'ropen' it would weigh less than 100kg.

His proposed ray exist in the oceans with the wingspan he proposes, but weigh in about three metric tonnes, THIRTY times the weight of the scaled up Albatross.

A Cessna weighs less than a tonne. About 700kg, and has a 75Kw engine. If we try and fly something weighing three tonnes, well, we can soon see the energy requirements are HUGE.

So what's he going to say next, maybe he'll propose light weight rays, but then forget that their density needs to be about that of water, or they'd float, and not be able to dive ever. Maybe he'll forget he needs that 6 metre wingspan to fit the silhouette of the cryptozoological creature.

Maybe he'll propose it flies using magic.
 
phlogistician said:
Maybe he'll propose it flies using magic.
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No no no, it'll clearly be proof of his new theory of gravity, where the core of the ray is filled with 'non-baryonic matter', just like he thinks the Sun is, and that'll allow it to fly and swim normally and it also means it won't leave any fossils so that's why there's no evidence for his claims.

It all fits perfectly, his new gravity theory proves his cryptozoology theories!

:rolleyes:
 
Right, just listen for a minute. The weight to lifting_area ratio of the proposed ray needs to be compared with the weight to lifting area of a flying fish. Its that simple.
 
common_sense_seeker said:
Right, just listen for a minute. The weight to lifting_area ratio of the proposed ray needs to be compared with the weight to lifting area of a flying fish. Its that simple.
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And if you understood any basic principles of fluids you'd know that your claims are flawed.

Animals are generally internally moist (ie blood, tissue liquids etc) and so their density is generally around that of water. Therefore floating at a specific depth in water can be achieved purely by buoyancy principles (like those used by submarines), no energy is required to stay a set distance from the surface. That isn't the case in air. All animals are much denser than air and so in order to remain off the ground energy must be expended.

As someone pointed out, birds are specialised for this. They have very light bones and the cores of feathers are hollow to reduce their weight and thus energy requirements as much as possible. A bird with dense bones is going to get tired and eaten quicker than its friends.

Then consider a ray. It is 'flying' in water usually and has almost no need to expend energy to stay at a particular depth. Moving through the water is then best done by having a streamlined body but the body is specialised for streamlined swimming not producing lift. Birds must constantly produce lift, rays don't, they just change their buoyancy. So ocean dwellers are generally much denser than fliers.

Then there's another problem, that of scaling. A ray 2 metres in length is 8 times more massive than a ray 1 metre across. And, even allowing for the assumption that it's a 'flying wing', the big ray has only 4 times the surface area as the smaller one. Doubling the size of the ray halves its lift to weight ratio! That's why larger birds have disproportionally larger wings compared to smaller birds. A sparrow's wings are about the same size as its body length. An eagle's are much larger than its body length, because its more massive. This scaling issue reveals itself everywhere in Nature. Ants don't have lungs, they absorb air through their skin (well, holes in their shells). We can't do that, we don't have enough skin surface area to supply our needs, hence why our lungs are folded over so much, the surface area is the size of a tennis court.

The problem with the rays is their 'wings' are too massive. The lift they might (might
) get from having larger 'wings' is more than off set by the additional mass of the wing. Hence feathers, they had more lift than they weigh so its worth having them.

CSS, you once again show you haven't got a clue about even the basics of mechanics and anatomy. This isn't even university stuff, its basic high school material (or if you're in the UK, as I suspect you are, secondary school).
 
There is something about figuring wing lift that is very well known to real aerodynamic experts. And you know who even knows it too. It is something of quite notable importance in the size range of wings that you all are discussing.

Lift is rigorously never a simple function of wing area X lift coefficient. However, in many cases the simple formula gives a close enough answer to be useful when ballpark grade numbers are good enough.

In your size range there is a scale factor. In such a wing size range, the lift is pretty much in proportion to the volume of the wing. Not simply its area. A ray fish that is bigger would indeed have greater lift pretty much in proportion to its greater weight which may be guessed to be pretty much in proportion to its greater volume.

The scale factor levels off with greater wing size. At the size of jet fighters and airliners and such like, the scale factor dies down to being negligible. Professional aerodynamicists do not pay much attention to lift scale factor of wings only a few feet in dimension. The wings in their daily work are much larger. Many probably have forgotten about it since classroom days. Model aviation enthusiasts are acutely aware of it. Model wings ranging from a few inches in dimension to a few feet have very noticeable lift differences proportional to their "volume" and not simply their area. This is always a very serious matter to the hobbyist.
 
Uno Hoo said:
There is something about figuring wing lift that is very well known to real aerodynamic experts. And you know who even knows it too. It is something of quite notable importance in the size range of wings that you all are discussing.

Lift is rigorously never a simple function of wing area X lift coefficient. However, in many cases the simple formula gives a close enough answer to be useful when ballpark grade numbers are good enough.

In your size range there is a scale factor. In such a wing size range, the lift is pretty much in proportion to the volume of the wing. Not simply its area. A ray fish that is bigger would indeed have greater lift pretty much in proportion to its greater weight which may be guessed to be pretty much in proportion to its greater volume.

The scale factor levels off with greater wing size. At the size of jet fighters and airliners and such like, the scale factor dies down to being negligible. Professional aerodynamicists do not pay much attention to lift scale factor of wings only a few feet in dimension. The wings in their daily work are much larger. Many probably have forgotten about it since classroom days. Model aviation enthusiasts are acutely aware of it. Model wings ranging from a few inches in dimension to a few feet have very noticeable lift differences proportional to their "volume" and not simply their area. This is always a very serious matter to the hobbyist.
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I appreciate another opinion on the matter. Incidentally, I once bought an excellent model glider with it's wings made from tent material, it being stretched into an 'arc' when the outer oval is bent into a curve to make a saddle shape. German design with no volume to the wing area. It flew beautifully and weighed next-to-nothing.

People seem to be obsessed with imagining a 20 ft manta-ray flying. There's no good reason why a SMALL ray the size of a flying fish couldn't evolve sustained gliding in the same manner. It's irrefutable surely?
 
Flying fish have very thin, light wings. A ray of the same size does not.

You really don't seem to grasp how science works, do you? You don't say "Prove me wrong!" and expect people to believe you until proven wrong, people disbelieve you until you provide evidence. It's presently irrefutable that the center of one of Pluto's moon is made of chocolate. But I cannot provide evidence for it and it is in direct contradiction to what we do know about planet formation. Being irrefutable is not the same as being right.

The anatomy of a flying fish compared to a ray is very different. The mechanics of flight in air is very different to swimming in water. This are points you have failed to address and seem unable to. If you can't provide a good motivational reason other than your desperate wish to explain cryptozoological animals which may or may not exist then why on Earth should anyone listen to you?

I asked you this before about your gravity claims. You defended them repeatedly with "Prove me wrong!" and then someone did. Why didn't you learn from that lesson?

Oh yeah, 'cos you're a fool.
 
Every airfoil has a volume. Flat plate and curved flat plate airfoils are considered to have a mean aerodynamic chord. This is an imaginary line drawn "midway" between the real top curve of a curved plate plate wing and a bottom line drawn between the center of the radius of the leading edge and the tip end of the trailing edge. The volume of the curved flat plate airfoil would be calculated as the cross section area between these two imaginary lines X the wing span, properly pro rated to allow for tapered leading or trailing edges or curved leading or trailing edges.

Talk about wing volume is a simplification of the rigorous method for exactly calculating wing lift. Rigorous lift analysis involves Reynold's Number, viscosity of the working fluid (such as air, or, water) et al. Look up Reynold's Number to get started learning about this stuff in a much more complicated way than speaking of the wing volume approximation. You will find that, for the range of small sizes in this discussion, and the small range of low speeds, "wing volume" gets you into the ball park.
 
 
common_sense_seeker said:
People seem to be obsessed with imagining a 20 ft manta-ray flying.
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Obsessed? No. You brought the dimensions to the table, not us.

There's no good reason why a SMALL ray the size of a flying fish couldn't evolve sustained gliding in the same manner. It's irrefutable surely?
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But that doesn't explain your 'ropen' does it? You allege a 6 metre wingspan, not a 'small' sized ray, flying about.

But anyway, how big is a 'small' ray? How much does it weigh? What's it's density compared to a bird? Oh, it's more dense, whatever the size, so must actually be MORE EFFICIENT at flying than a CREATURE EVOLVED FOR FLIGHT.

So yes, it is refutable, and that has been demonstrated to you over and over again, but you are too thick to accept it.
 
common_sense_seeker said:
A ray's body can act as a lifting surface, the body of flying fish is the wrong shape. Hence the ray has an aerodynamic advantage from the start.
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A ray is the shape it is because its streamlined to move through the water with minimal effort. Same goes for a fish. Neither of them are shaped for producing lift. They control their depth by altering buoyancy. A ray doesn't sink when it stops moving nor does it glide upwards when it starts moving forwards.

Superficially a ray might seem aerodynamic when compared to something like a B2 bomber but that's it. The B2 bomber required an enormous amount of research because 'flying wings' produce LESS lift than usual plane designs. The design has to be just right in order to get enough lift for the B2 to fly. There's a much larger margin of error for normal planes.

Wings can evolve from thin flaps of skin in a gradual process. Flying foxes or those jungle frogs don't fly so much as slow their falling. Over time this can evolve into more specialised and better flying limbs. Doesn't work like that with flying wings. If the aerodynamics isn't right you don't get any benefit. Flying fish obviousl developed their 'wings' gradually, each iteration adding new benefits. A ray isn't going to be able to do that, it's shape is simply not going to provide enough lift for the typical speeds they swim at.

The B2 has a higher take off speed than a jumbo jet because its shape provides poor lift. Hence the need for powerful engines. In the animal world this would mean the rays have to be moving much much faster than the flying fish to get anywhere near the kind of 'flight' capabilities they have. And flying fish swim pretty damn quick.

This isn't complicated stuff. I sat one course in fluid mechanics 6 years ago (jesus, that makes me feel old.....) and am just applying those basic principles and results I read about in books. You claim to have done aeronautics and read pop science books and you're bloody clueless!
 
common_sense_seeker said:
A ray's body can act as a lifting surface, the body of flying fish is the wrong shape. Hence the ray has an aerodynamic advantage from the start.
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As stated before, there IS a perfectly good mechanism for the evolution of sustained gliding (i.e. soaring) in the rays: getting rid of parasites. More oxygen is gained from air than water, so stiffened gills would extract more oxygen for a more powerful wing flap against the water. An added evolutionary advantage is the ability to soar away from enemies, as in the case of flying fish. No matter what the insults (which I don't read), it IS a distinct possibility IMO.
 
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