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Old Feb 17, 2014, 07:06 PM
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Pteronautn, are saying you're going to commercializ wings that will go on an actual ornithopter, or wings for educational purposes?
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Old Feb 17, 2014, 07:19 PM
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Originally Posted by G-LO View Post
Pteronautn, are saying you're going to commercializ wings that will go on an actual ornithopter, or wings for educational purposes?
On all sorts of actual ornithopters. I'm most interested in applying it to manned flying machines.
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Old Feb 18, 2014, 01:17 AM
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Pteronaut..to create a flapping wing model that really flies is one big step. And I am not talking about a simple membrane wing. Most people talk about it but never succeed. An flapping wing that flies and with the right articulation is a big step more. The next huge step is folding or bending. I would suggest to do it step by step to understand the problems because it is so much more complex. All feathers of a bird are controlled by muscles to keep them in the right position. I filmed my hawk in slow-motion to get an idea:

Goshawk in slow-motion (1 min 20 sec)
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Old Feb 18, 2014, 08:24 AM
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Originally Posted by bluefalconhollan View Post
Pteronaut..to create a flapping wing model that really flies is one big step. And I am not talking about a simple membrane wing. Most people talk about it but never succeed. An flapping wing that flies and with the right articulation is a big step more. The next huge step is folding or bending. I would suggest to do it step by step to understand the problems because it is so much more complex. All feathers of a bird are controlled by muscles to keep them in the right position. I filmed my hawk in slow-motion to get an idea:

http://www.youtube.com/watch?v=dj2ziYV9Feo
Beautiful bird you have there.

It would be very difficult, if not impossible to model all the functionality of your hawk. It has a very dynamic set of capabilities.

I think it is possible to achieve a practical folding wing with much less range of motion than we see in your hawk. Picture a wing that can fold some, but can not fold all the way in and tuck into the body. Just a little bit of fold goes a long way.

This albatross is operating within a range of motion that I think is much more achievable than what your hawk is utilizing:
(I can't figure out how to embed the video here)

http://www.arkive.org/black-footed-a...video-06c.html
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Old Feb 18, 2014, 10:52 PM
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@ Arthosaur

My thoughts about 3D articulation

In order to succeed we have to put on ourselves some limitations !
Your last post show me that you understand that. "Put in everything" designs usually doesn't work and lead only to frustration , los of motivation, waste of time and spending a lot of money without reaching the desired result.
The proper way is to go forward step by step and I will try to point out these steps.

1. Concentrate on only one specific type of bird ( not on "arthopters" in general !
Bats have evolved towards maneuverability , if the pterosaurs have
been adequate they would have ménage to exist until today and wouldn't have had to evolve in to birds.

2. Choose the right type of bird for emulation -in the range of those ones which move thru the air mainly by flapping .Ducks for example ! Ornithologists opinion is that moderate aspect ratio wings work best for flapping flight. -dew to lower inertia and higher relative strength

3. Concentrate only on an specific regime of flight of the chosen bird (It's logical to be chosen the most used one the cruising flight)

4. The membranes even the stretchable ones can't match even close the performance of "feathered" wings not only because of reduced range of wing articulation/folding but mostly because of lack of progressive elasticity along the wing chord and span . This is related to the "in the wing energy recuperation" (during the up stroke and in the ends of up and down strokes) and the wings auto adaptivity against the airflow.

5. You no need of feathers until you give up to complete folding and high amplitude articulation as during take off / lending /hovering ,so the wings can be divided on few zones which can be covered by thin elastic plates of composites or elastic plastic which slide over each other in the joints areas.
The thickness of the plates have to be higher close to the "wing bones" and thinner to the trailing edge in order to achieve progressive elasticity or better by overlapping uniform thickness sheets as in the leaf springs .

6. Most of the engineers/inventors didn't know that but elbow and wrist joints fold/unfold synchronously which make the task a bit easier. Also many of them didn't know about the last wing finger joint which is very important for changing the wing tip shape what to say about alula feathers and their impact on the boundary layer.

7. Wings control mechanisms have to be placed in the fuselage and connected to the relative joints by strings/pulley system in order to keep the wing masse and inertia as low as possible.

8. There is the harder wing part for emulation which is the leading edge between shoulder and wrist joints and it is responsible (along with other muscles) for changing/adjusting the inner wing chamber for optimal L/D ratio .

There are my favorite examples for articulating wings underling structure and wing covering the combination of which illustrate an faceable way of solving the articulation problem (in the earlier limited already range)

Morphing aircraft mimics a bird's wing (0 min 48 sec)


University of Florida: Radical Airplane Design (4 min 28 sec)


Duck WIng (0 min 40 sec)


ORNITOPTERO EXPERIMENTAL, PATRICIO ALDAO,VILLA CONSTITUCION,SANTE FE,ARGENTINA (2 min 59 sec)


Maquina de voar, anatomia mecânica aves, não Ornitóptero (fly machine articulated, not Ornithopter) (4 min 50 sec)
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Old Feb 19, 2014, 11:32 AM
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:Thanks very much for your input Seagull10. I think we have similar perspectives on articulating wing flight.

1. Concentrate on only one specific type of bird ( not on "arthopters" in general !
Bats have evolved towards maneuverability , if the pterosaurs have
been adequate they would have ménage to exist until today and wouldn't have had to evolve in to birds.

I only discuss arthropters in general to point out the underlying system that all 3 groups share. Nature has arrived at this system independently 3 times. This convergent evolution is remarkable and we should pay very close attention to what all these groups share.

I have chosen a basic bird type to focus on as my model: gulls. It is also an arthropter .

Regarding Pterosaurs. You might take another look. I'm not sure their effectiveness at flight had anything to do with their extinction. Very few animals survived the KT extinction. Pterasuars did not "evolve into birds", the 2 groups are separate, independent lineages. The largest pterosaurs had wingspans and mass greater than what a human would require (estimates range, but 35 foot wingspan, 350 lbs!!). Studying how they worked may be as valuable as studying birds and certainly complimentary.

2. Choose the right type of bird for emulation -in the range of those ones which move thru the air mainly by flapping .Ducks for example ! Ornithologists opinion is that moderate aspect ratio wings work best for flapping flight. -dew to lower inertia and higher relative strength

Again, I am modeling gulls as they have long slender wings for efficient gliding and reduced drag and also resemble the large pterosaur wings in aspect raitio


3. Concentrate only on an specific regime of flight of the chosen bird (It's logical to be chosen the most used one the cruising flight)

My primary focus is wing articulation for manueuver/control and optimizing gliding efficiency. If this can be achieved, you will also have all the necessary elements for flapping flight.

4. The membranes even the stretchable ones can't match even close the performance of "feathered" wings not only because of reduced range of wing articulation/folding but mostly because of lack of progressive elasticity along the wing chord and span . This is related to the "in the wing energy recuperation" (during the up stroke and in the ends of up and down strokes) and the wings auto adaptivity against the airflow.

I agree that progressive elasticity along the chord is of critical importance, but there is no reason you can't optimize elasticity and deflection in a membrane wing. There are advantages to membranes and also disadvantages. A hybrid approach between feather and membrane can reduce many of the drawbacks that you typically see in membrane wings. I favor a membrane wing comprised of numerous overlapping members (like feathers, but fewer)

5. You no need of feathers until you give up to complete folding and high amplitude articulation as during take off / lending /hovering ,so the wings can be divided on few zones which can be covered by thin elastic plates of composites or elastic plastic which slide over each other in the joints areas.
The thickness of the plates have to be higher close to the "wing bones" and thinner to the trailing edge in order to achieve progressive elasticity or better by overlapping uniform thickness sheets as in the leaf springs .

I get your basic point and agree generally. Thinking of the wing as separate "zones" is good. "Plates" sound to heavy and rigid. I like fabric around framework which is rigid in some ways and flexible in others. The goal is to achieve a basic construction and architecture that can be optimized by changing its parts without redesigning the entire wing.

6. Most of the engineers/inventors didn't know that but elbow and wrist joints fold/unfold synchronously which make the task a bit easier. Also many of them didn't know about the last wing finger joint which is very important for changing the wing tip shape what to say about alula feathers and their impact on the boundary layer.

Yes. Bird wings have a double joint at elbow and wrist that creates a parallelogram which allows passive wing tip fold when the wing is folded.

7. Wings control mechanisms have to be placed in the fuselage and connected to the relative joints by strings/pulley system in order to keep the wing masse and inertia as low as possible.

Agreed

8. There is the harder wing part for emulation which is the leading edge between shoulder and wrist joints and it is responsible (along with other muscles) for changing/adjusting the inner wing chamber for optimal L/D ratio .

Yes, this is the propatagium and it is present in all 3 natural model arthropters (birds, bats, pterosaurs). I agree that the propatagium must be present for an effective folding wing. With correct tension and elasticity, I think the propatagium can serve its function as a passive slave to the fold range of motion If it is designed well in a man made wing, it does not have to be actively controlled

There are my favorite examples for articulating wings underling structure and wing covering the combination of which illustrate an faceable way of solving the articulation problem (in the earlier limited already range)
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Old Feb 19, 2014, 11:13 PM
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Took me years to escape from gulls magic and to realize that if we looking for a model for flapping human personal transportation machine we have to look between migratory birds because we need a vehicle which move us from point A to point B in safe , fast , affordable and with lowest possible environmental impact manner and it with no mater of wind blowing direction !
Gulls are genial wind riders as BTW I hope pterosaurs have been (nobody doesn't know that exactly and probably the disputes about : have they been able of powered flapping flight continues till today) The question is what happens when there is no wind or even worst the wind blow against the direction we heading.

The fastest migratory bird on the planet without tailwind support:
http://phys.org/news/2011-05-great-s...tory-bird.html

Interesting video

Paleoworld Flight Of The Pterosaurs (25 min 11 sec)
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Old Feb 24, 2014, 12:16 PM
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Seagull10-

I'm glad you took a closer look at the pterosaurs. Keep in mind that this video is 20 years old and the fossil record has exploded with new finds and data since then. I tried to find something more up date, but there isn't much up on youtube. You can rent the attenborough movie and it's well worth it, though a little too much CGI and not enough science:

http://video.nationalgeographic.com/...sters-trailer/

The idea that pterosaurs were not capable of powered flight is preposterous to me (of course, their ancestors were likely only gliders)

Ther are many other resources if you are interested:
http://www.pterosaur.net/flight.php
http://www.ucmp.berkeley.edu/diapsids/pterosauria.html


It's worth noting that pterosaurs are thought to have overcome the size limitations of birds because they used the same muscles for takeoff and flapping. Where birds had to have strong legs for take off and strong wing muscles for flapping, pterosaurs were able to focus their resources on their front limb muscles while the hind limbs stayed relatively small.


Quote:
The fastest migratory bird on the planet without tailwind support:
http://phys.org/news/2011-05-great-s...tory-bird.html
Maybe. Gulls will be a fine model though. I don't think trying to fly as fast as possible should be the primary goal. Control is much more important than speed. We can figure that out later.
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Old Mar 07, 2014, 06:40 AM
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Good example of superiority of the active articulation


Like a Bird - Original Ornithopters Demonstration (8 min 46 sec)
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Old Mar 07, 2014, 07:33 AM
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Originally Posted by seagull10 View Post
Good example of superiority of the active articulation


https://www.youtube.com/watch?v=Uf6EAzEmpfU
What is the superiority ?
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Old Mar 07, 2014, 08:40 AM
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What is the superiority ?
Velkov , If you can't see that what is evident , it's OK and I can explain it to you, but IMO the problem is that you just don't want to see it so I'm going to save my time.
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Old Mar 07, 2014, 09:46 AM
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Velkov , If you can't see that what is evident , it's OK and I can explain it to you, but IMO the problem is that you just don't want to see it so I'm going to save my time.
Otto, I can see this too:

66" RC Ornithopter (0 min 28 sec)


Trial of Making of membrane wing with an articulation which bends to a one direction (19 min 42 sec)


This is passive articulation.
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Old Mar 07, 2014, 11:30 AM
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That "like a bird" video is the best I've seen. Both models are beautiful examples, but it's hard to see how active wing tip dip articulation would not be superior to passive wing tip dip articulation since it allows the wing to return to the up position faster.

Also, if you want to be able to use wing tip dip for control only (not flapping) you have to be able to actuate it actively and independently of flap.
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Old Mar 08, 2014, 02:06 AM
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Originally Posted by seagull10 View Post
Good example of superiority of the active articulation


https://www.youtube.com/watch?v=Uf6EAzEmpfU
The action of the wing at different frequencies is the same.

This is not superiority.
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