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Old Dec 16, 2011, 06:12 AM
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Ornithoid with passive articulated adaptive wing 2

http://velkovelkov.blogspot.com/2011...ticulated.html
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Old Dec 16, 2011, 12:42 PM
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You know Velko, I see no reason why the bobbing mechanism wouldn't work as long as you use the right wings. I'd be willing to bet you might get airborne if you stuck a set of Lazy Hawk wings onto that bobbing pylon mechanism. But you have two experimental designs in your machine..the bobbing central pylon, and the semi-span wing hinges. Why don't you test the pylon without the hinged wings? Try a rigid leading edge spar first which is a proven design that will more likely get airborne, then experiment with the wing hinges afterwards. Just a suggestion.
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Old Dec 16, 2011, 10:30 PM
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Originally Posted by Velko Velkov View Post
Hi Velko Velkov,

This one is better than ornithoid #1 at least because the driving mechanism
will generate less drag.
Did you perform some static or/and field tests already?
Please post some videos if you have it.


Success !

Otto
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Old Dec 17, 2011, 09:53 AM
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Sean, Otto,

Thank you for your comments. See video:

ORNITHOID WITH PASSIVE ARTICULATED ADAPTIVE WING (0 min 44 sec)
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Old Dec 17, 2011, 12:33 PM
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Ahhh Velko! Come on, nother teaser??? I was getting excited thinking this video was going to show an actual launch! I was ready to cheer you on!

I know that is probably your only model and you don't want to risk destroying it. Trust me, I've been there. My early VT-1 flights were like that. But you have to see what the machine will actually do unthethered so you need to give it a toss. You don't have to do that on video if you don't want to but you will learn a lot by doing it. Even the SkyBird has an awkward ROG although I have ROG's it extensively. But you may find your machine does a lot better from a hand toss than from an ROG attempt, even if it only achieves a powered descent at first until you work the bugs out.

Just one more observation...just as all birds and ornithopters have a mechanical wing hinge point, they also have an aerodynamic wing hinge point. It's more pronounced in ornithopters than live birds because they lack wing folding but the aerodynamic hinge point is produced because the body of the machine bobs up and down a certain amount with each flapping stroke. This places the aerodynamic hinge point further out along the wing spar than the mechanical hinge point.
This makes me wonder about your bobbing wing design. In the air will the body have enough mass to insure the wings do the bobbing and not the body? The body due to its weight will always bob and impart energy into the system but I'm just wondering if the wings will bob a lot less in flight than on the ground or in the hand. I would see where you would probably need to concentrate all possible weight into the core fuselage so the wings work against the mass of the body. Just musing here. It's your invention. You tell us!
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Old Dec 17, 2011, 12:52 PM
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yeah, like to see it get airborned. Actually, if he can find a soarable ridge would be an idea for slow flapping devices.
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Old Dec 17, 2011, 12:58 PM
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Does anybody else here see what I'm saying? Won't the wings flowing through the airstream try to act like a horizontal stab themselves and simply try to bob the body up and down? Like I said, I don't think it can help but impart energy into some form of thrust but I just imagine a throttle burst resulting in a very fast body bob instead of a fast wing bob. Not being critical. Just wondering out loud.
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Old Dec 17, 2011, 01:35 PM
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I hear you that's why I am anxious to see how goes it once released
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Old Dec 17, 2011, 01:53 PM
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Originally Posted by Kinkade View Post
Ahhh Velko! Come on, nother teaser??? I was getting excited thinking this video was going to show an actual launch! I was ready to cheer you on!

I know that is probably your only model and you don't want to risk destroying it. Trust me, I've been there. My early VT-1 flights were like that. But you have to see what the machine will actually do unthethered so you need to give it a toss. You don't have to do that on video if you don't want to but you will learn a lot by doing it. Even the SkyBird has an awkward ROG although I have ROG's it extensively. But you may find your machine does a lot better from a hand toss than from an ROG attempt, even if it only achieves a powered descent at first until you work the bugs out.

Just one more observation...just as all birds and ornithopters have a mechanical wing hinge point, they also have an aerodynamic wing hinge point. It's more pronounced in ornithopters than live birds because they lack wing folding but the aerodynamic hinge point is produced because the body of the machine bobs up and down a certain amount with each flapping stroke. This places the aerodynamic hinge point further out along the wing spar than the mechanical hinge point.
This makes me wonder about your bobbing wing design. In the air will the body have enough mass to insure the wings do the bobbing and not the body? The body due to its weight will always bob and impart energy into the system but I'm just wondering if the wings will bob a lot less in flight than on the ground or in the hand. I would see where you would probably need to concentrate all possible weight into the core fuselage so the wings work against the mass of the body. Just musing here. It's your invention. You tell us!
Sean,

This "demonstration" is after toss. The "flight" was not interesting. The model is to hevy-1,6 kg /wing span-1,8 m/. The materials are mainly aluminium and fiberglass. CG was forward. But this is the beginning. I hope #2 will be better.

Velko
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Old Dec 17, 2011, 01:54 PM
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Originally Posted by Kinkade View Post
Does anybody else here see what I'm saying? Won't the wings flowing through the airstream try to act like a horizontal stab themselves and simply try to bob the body up and down? Like I said, I don't think it can help but impart energy into some form of thrust but I just imagine a throttle burst resulting in a very fast body bob instead of a fast wing bob. Not being critical. Just wondering out loud.
While watching the video, I asked myself if this "Ornithoid" would end up as Tail flapper but perhaps with a bigger tail, more like a tandem wing...
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Old Dec 17, 2011, 02:22 PM
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Originally Posted by Velko Velkov View Post
Sean,

This "demonstration" is after toss. The "flight" was not interesting. The model is to hevy-1,6 kg /wing span-1,8 m/. The materials are mainly aluminium and fiberglass. CG was forward. But this is the beginning. I hope #2 will be better.

Velko
At least you tried. Don't give up. If you are using fiberglass spars I think it would help to switch to carbon if you can get them.
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Old Dec 18, 2011, 12:57 AM
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Originally Posted by Velko Velkov View Post
Sean,

This "demonstration" is after toss. The "flight" was not interesting. The model is to hevy-1,6 kg /wing span-1,8 m/. The materials are mainly aluminium and fiberglass. CG was forward. But this is the beginning. I hope #2 will be better.

Velko
Velkov,

Thank you for the video and congratulations for the bravery to toss it in the air . It seems the video is showing your previous model #1.
I disagree with you about your statement: "The "flight" was not interesting". If you have video of the "flight", please show it here. I am sure nobody will laugh and the guys will be glad to help you with analyzing and debugging your machine. I am sure you can do this alone but it will take longer, and I am not sure if your patience will be enough for that. I have watched your work for a long time /because I like it / and I'm afraid that you will start building a new machine before taking the current one in the air.
Kinkade's analysis and notes are very good. I only disagree with him about the statement that his stock wings will work better than yours.IMO yours are better because of the chord curvature and use of ribs.They seems to be much more rigid which is better in your case. Also I'm not sure what the purpose of the ornithoid's wing articulation is, and that's why I like your very first not articulated ornithoid model more. IMO only spring loaded adaptive central hinge is enough.
LIG's idea:ridge soaring test is very good , I just don't know how good of a pilot you are and whether you have appropriate sites around you.

Overall, good effort.

Otto
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Old Dec 18, 2011, 05:46 PM
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Otto,
I like the way Velko's wing looks but to date as far as we know it has never produced actual flight. How can he learn anything from a new bobbing concept with a wing that itself has not been proven to produce flight while flapping? It just makes sense to separate the two experimental concepts so you can better assess each. A flapping Lazy Hawk ( or similar rigid spar membrane wing) works. Since we know it works while flapping, a wing like that would better allow assessment of the bobbing concept. I just suggest he fabricate a Lazy Hawk style wing so he can learn what the bobbing system has to offer without getting potentially false data caused by a non proven wing.
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Old Dec 19, 2011, 06:37 AM
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Originally Posted by Kinkade View Post
Otto,
I like the way Velko's wing looks but to date as far as we know it has never produced actual flight. How can he learn anything from a new bobbing concept with a wing that itself has not been proven to produce flight while flapping? It just makes sense to separate the two experimental concepts so you can better assess each. A flapping Lazy Hawk ( or similar rigid spar membrane wing) works. Since we know it works while flapping, a wing like that would better allow assessment of the bobbing concept. I just suggest he fabricate a Lazy Hawk style wing so he can learn what the bobbing system has to offer without getting potentially false data caused by a non proven wing.
+1

Khaled
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Old Dec 19, 2011, 12:16 PM
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Originally Posted by khaled_abobakr View Post
+1

Khaled
Kinkade and Khaled,

I totally agree with the old aircraft designers methodology that there should be "No more than one new unproven element in every new aircraft" because this rule has been written with a lot of human blood.
We are of course far from this jeopardy but just following the rule helps to hold the things under control.
The aerodynamic science and practice have proven that in terms of ratio :useful aerodynamic force(lift+thrust for us) /drag, curved surfaces are better than planes, and profiles are better than simply curved surfaces. So I don't think that Velkov's wing is cutting edge technology but I think that it's better than yours at least as a concept.
This is not meant as an offense, Kinkade. I know the limitations imposed by mass production and the need to keep the cost low in order for the product to be more affordable, but to say that this type of wing is better than Velkov's just won't be the truth.

Otto
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