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Jul 28, 2021, 08:46 AM
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Dantiel's Avatar
a problem in the flapping amplitude is backlash , because especially in small models the resulting amplitude will always tend to be lower than what you meant. in your video it looks like the resulting is 35degrees.... therefore it needs increasing or fixing the mechanism, just try for fun increase it to the maximum possible and check what performance you can get out of the wing.
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Jul 30, 2021, 09:38 AM
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Thread OP
I try to make articulated wing for small ornithopter which has no link but only use elastic & normal fishing line.
This mechanism is very light and easy to set up. I will set this to my Alula type2 to check flight condition.
This trial wing detail:
1) Wing: Depron 2mm
2) Inner and outer wing hinge uses 3M medical tape ( under side only)
3)Upper string is 0.5mm elastic beading thread, and lower is 0.27mm beading thread.
The aiming of this method is to keep from disturb bending action during up stroke and keep outer wing straight during gliding.
The video is not so clear how this mechanism works but just after upper most point outer wing quickly return to the straight position.
An idea of the articulated wing mechanism for small ornithopter (1 min 15 sec)
Jul 30, 2021, 12:50 PM
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Dantiel's Avatar
it is very interesting see new types of articulation, but it seems to me that this one is only passive, you may want to check out birds with active articulation in kazu's thread. active articulation = outer wing moves with higher angular velocity (bigger amplitude) than inner part of wing
Jul 30, 2021, 05:42 PM
K Kakuta
Kazu-kaku's Avatar
Quote:
Originally Posted by Dantiel
it is very interesting see new types of articulation, but it seems to me that this one is only passive, you may want to check out birds with active articulation in kazu's thread. active articulation = outer wing moves with higher angular velocity (bigger amplitude) than inner part of wing
Passive Articulated wing may decrease thrust.
Jul 30, 2021, 08:15 PM
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Thread OP
So I use elastic thread to upper.
Jul 31, 2021, 02:14 AM
K Kakuta
Kazu-kaku's Avatar
Quote:
Originally Posted by kajiyama
So I use elastic thread to upper.
I use Piano line.
Aug 15, 2021, 01:50 PM
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NChronister's Avatar
John's Birds, do you use an actual glide lock mechanism in those ornithopters, or is it just designed to glide when the wings go up in a V? I had good results with the latter approach, but I don't know of any reliable glide lock mechanism (except for rubber band powered ornithopters).
Aug 18, 2021, 12:15 AM
Registered User
Quote:
Originally Posted by NChronister
John's Birds, do you use an actual glide lock mechanism in those ornithopters, or is it just designed to glide when the wings go up in a V? I had good results with the latter approach, but I don't know of any reliable glide lock mechanism (except for rubber band powered ornithopters).
Nathan,
I use a Sean Kinkade style wing lock mechanism with an Arduino+Hall sensor to stop the motor and then the wings lock reliably. Here is a video showing repeated flap-glide cycles and the wings never fail to lock.

Steve

RC Ornithopter with Intermittent Flapping Flight (0 min 47 sec)
Aug 23, 2021, 12:22 PM
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NChronister's Avatar
Hi Steve. You've been getting some amazing flights with the new wing design. Did you get the email I sent you recently? I live in the bay area now.
Aug 26, 2021, 02:07 AM
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Johns birds's Avatar
Quote:
Originally Posted by NChronister
John's Birds, do you use an actual glide lock mechanism in those ornithopters, or is it just designed to glide when the wings go up in a V? I had good results with the latter approach, but I don't know of any reliable glide lock mechanism (except for rubber band powered ornithopters).
Sorry Nathan I did not check this tread recently. I explained in my thread there
https://www.rcgroups.com/forums/show...evival-project
how my glide lock mechanism works. Wings locks in predetermined dihedral position, not in top
position which would be fast descent in pigeon glide mode.
Sep 05, 2021, 07:56 AM
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G-LO's Avatar
Very interesting. The first forward swept ornithopter design I have seen anyone attempt to build. Especially with this much degree of sweep. Great job, Kajiyama. Thanks for keeping us posted on you progress!
Sep 06, 2021, 12:43 PM
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XXXmags's Avatar
Quote:
Originally Posted by kajiyama View Post
I have experience for fixed wing plane which has V-tail and No-tail as well.
But ornithopter has very interesting due to different flight characteristics comparing to fixed wing...
Hi Kajiyama,

First off, great job on this unique ornithopter! thanks for sharing with it us. You mentioned the ornithopter flies differently compared to what you're used to. Could you provides more details about these observations?

For example, how did the handling change between flapping flight and gliding flight?
It's been my experience an ornithopter can become harder to turn once the wings begin to flap, but this was with an aircraft with a tail.

Another thing might be the in-flight trim. In gliding flight I can see your model behaving like any model with a reflexed airfoil, but does this change once you're in flapping flight?
Do you need more or less reflex to stay flying?
How does the aileron effectiveness change?

Thanks and please keep us posted on your progress!
Sep 07, 2021, 10:21 AM
Registered User
Thread OP
Quote:
You mentioned the ornithopter flies differently compared to what you're used to. Could you provides more details about these observations?

For example, how did the handling change between flapping flight and gliding flight?
It's been my experience an ornithopter can become harder to turn once the wings begin to flap, but this was with an aircraft with a tail.

Another thing might be the in-flight trim. In gliding flight I can see your model behaving like any model with a reflexed airfoil, but does this change once you're in flapping flight?
Do you need more or less reflex to stay flying?
How does the aileron effectiveness change?
Type 1 has elevon system so it can control roll & pitch easily even has not so flex wing material. I set 5degrees reflex as initial setting, and has elevator mixed with throttle which move linearly increase 5degrees more until max throttle. You may adjust this value with try and error.
Fix wing case, there is no problem even if there has no rudder function, it very easy to turn only with elevon. But type1 has difficulty to turn during flapping without rudder. And very interesting matter is vertical stabilizer with rudder function characteristic which need to incline clockwise when turn to the right and vise versa. And of cause aileron mixed with rudder .
During gliding, there is exactly same controllability with normal fixed wing without tail.
Type 2 has wingeron so there has some difficulty for pitch control without enough flexible wing material case. I preset reflex 6degrees and this is good enough for the gliding but not enough for the flapping if there is harder material wing. Type2 has 1mm EPP wing which has enough flexibility to keep stable pitch moment. And type 2 also has throttle & elevator mix with same degree of type1 which is good enough for the 1mmEPP wing but not enough for harder material wing.
Type2 gliding condition is totally same as type1 . And also rudder function is same as type 1 too.
I am now confirming articulated wing on type2 which has interesting symptom which has better lift compare to the EPP wing without articulated.
After progress the trial I will up the content on this forum.


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