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Old Jan 23, 2013, 06:25 PM
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Originally Posted by seagull10 View Post
You are welcome Sir .Proud to be one of 'Kjellians' guys, as George described us
I said: "Or fishing for Kjellians." Fishing implies 'new' fish, not the ones already in the bag

I don't see anyone here, or any other orni thread, with 'his' attitude of tearing down what he does not understand and wanting to replace aerodynamic theory with his own speculative theory put forward as fact.

Those working on 'sine wave drives' I wish you success!
George
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Old Jan 23, 2013, 07:19 PM
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Originally Posted by Plantoflap View Post
I said: "Or fishing for Kjellians." Fishing implies 'new' fish, not the ones already in the bag

I don't see anyone here, or any other orni thread, with 'his' attitude of tearing down what he does not understand and wanting to replace aerodynamic theory with his own speculative theory put forward as fact.

Those working on 'sine wave drives' I wish you success!
George
I think he has pretty good understanding and explanation how fan - flapping ornithopter's wings work and especially to the moment when flapping speed is faster than forward speed. I will just suggest him to replace the term "Partial vacuum" with "Lower pressure area" everything else is OK for me.
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Old Jan 24, 2013, 05:57 AM
Kjell Dahlberg
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Originally Posted by seagull10 View Post
I think he has pretty good understanding and explanation how fan - flapping ornithopter's wings work and especially to the moment when flapping speed is faster than forward speed. I will just suggest him to replace the term "Partial vacuum" with "Lower pressure area" everything else is OK for me.
I understand that a low-pressure area is a region where the atmospheric pressure is lower than that of surrounding locations and a partial vacuum is anything between zero and 14.7 inHg.
I prefer calling it Partial vacuum on the phenomena that can change place in every wing stroke, (25 times/second on the humming bird flapping).
Some flies beat their wings up to 1000 times per second.
The “Kjell-Effect” is there in every stroke.
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Old Jan 27, 2013, 04:15 AM
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This seems to be a slightly different hybrid of the vwd, swashdrive, and wiggle drive. Unfortunately they've got a bloody basket of patents, fortunately they are all for changing reciprocal motion into rotary and not the other way around.

http://www.s-ram.com/home.html
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Old Jan 28, 2013, 05:35 PM
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Originally Posted by MattK_NZ View Post
This seems to be a slightly different hybrid of the vwd, swashdrive, and wiggle drive. Unfortunately they've got a bloody basket of patents, fortunately they are all for changing reciprocal motion into rotary and not the other way around.

http://www.s-ram.com/home.html
Hi Matt
I like the way the offsetting boss is handled, kinda like Kjells dog-leg boss (Bent shaft) !
What looks a little odd is in the animation, i see lateral piston movement produced from the arking swashplate...if you look closely you can see the piston moving out of concentricity of the said cylinder ! Karcha have similar patents on a system for a water blaster which they so kindly named swashdrive
I kinda wonder how useful all those patents are in todays world with all the copies / knockoffs that come out of china
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Old Jan 28, 2013, 06:57 PM
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Very nice catch, Craig, you must have watched that video more times than me or you have a better eye for detail.

I've been mulling this stuff over in my head for the past week and my current point of view is that these systems need to be designed around the type of thrust bearing available. For water contacting fin applications... A pair of ceramic angular contact bearings is required although a pair of ceramic tapered roller bearings would be better, if such a thing is ever manufactured. Unfortunately, outside China a pair of angular contact ceramic bearings will cost $USD240 for each drive.

For winged applications I'm quite sure a pair of needle thrust bearings will be best because of their low weight and their ability to be purchased / used without races so that the needles roll on the inner surfaces of the VWD.
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Old Jan 29, 2013, 01:31 AM
Kjell Dahlberg
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Originally Posted by MattK_NZ View Post
This seems to be a slightly different hybrid of the vwd, swashdrive, and wiggle drive. Unfortunately they've got a bloody basket of patents, fortunately they are all for changing reciprocal motion into rotary and not the other way around.

http://www.s-ram.com/home.html
About all this patents.
If the invention has been described in a printed publication anywhere in the world a patent cannot be obtained.
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Old Feb 04, 2013, 02:48 AM
Kjell Dahlberg
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The name of the VWD have to alter its name to Variable Swashplate Drive(VSD) and the Fixed Swashplate Drive (FSD).
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Old Feb 05, 2013, 12:29 AM
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Originally Posted by KJELL View Post
The name of the VWD have to alter its name to Variable Swashplate Drive(VSD) and the Fixed Swashplate Drive (FSD).
Gday Kjell
That is very humbling to read those words, thanks my new old friend
On my part it is now a little easier to understand !
Im working on an Orni (FSD) prototype at present, like your test setup with just one side operating on a rotating test boom....should have some footage soon i hope, just a lil busy with work & all

regards
Craig
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Old Feb 05, 2013, 04:12 AM
Kjell Dahlberg
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I am glad to hear that you are going to make a rotating test bench. Hoping to see pictures soom.
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Old Feb 06, 2013, 06:12 PM
Mad on everything Swash
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swashplate CV

Gday

I have been corresponding with Kjell and its seems apparent he is of the view that a swash action has a sine wave motion / Velocity. So i thought it good to open discussion on this mis-understanding.

it is a fundamental feature of a swash action to have a constant pitch / velocity and is infact not a sine wave path, but rather straight line.
In a practical sense, once the wing / fin rocks over to complete the change of direction, i.e. the pitch angle. The fin / wing remains at a fixed angle and constant velocity until it reaches opposite rock over / change of direction. With a 30 deg deflection angle / pitch the rock over is 30 deg of TDC & BDC.... 60 deg stroke.
attached is a hand plotted graph of a swash lateral moment, i.e. the reciprocating path / velocity and also the pitch path of the said fin / wing .
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Old Feb 07, 2013, 05:51 PM
Mad on everything Swash
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Originally Posted by Lil aus View Post
Gday

I have been corresponding with Kjell and its seems apparent he is of the view that a swash action has a sine wave motion / Velocity. So i thought it good to open discussion on this mis-understanding.

it is a fundamental feature of a swash action to have a constant pitch / velocity and is infact not a sine wave path, but rather straight line.
In a practical sense, once the wing / fin rocks over to complete the change of direction, i.e. the pitch angle. The fin / wing remains at a fixed angle and constant velocity until it reaches opposite rock over / change of direction. With a 30 deg deflection angle / pitch the rock over is 30 deg of TDC & BDC.... 60 deg stroke.
attached is a hand plotted graph of a swash lateral moment, i.e. the reciprocating path / velocity and also the pitch path of the said fin / wing .
Sorry guys and specially Kjell, my wrong
It is actually not a fixed pitch at all, it is a varying pitch throughout a 180 deg shaft rotation and is a type sine wave, it is only once deflection angle is greater than 45 deg that pitch becomes a straight line or fix pitch for a portion of stroke.
The graph i plotted is velocity of movement across the stroke and nothing else !
Now that I'm aware of this i have some doubt in its abiliity for flight it may be more useful in water were symmetry and a curved path is good !
....onwards
regards
Craig
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Old Feb 08, 2013, 07:13 AM
Kjell Dahlberg
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Originally Posted by Lil aus View Post
Sorry guys and specially Kjell, my wrong
It is actually not a fixed pitch at all, it is a varying pitch throughout a 180 deg shaft rotation and is a type sine wave, it is only once deflection angle is greater than 45 deg that pitch becomes a straight line or fix pitch for a portion of stroke.
The graph i plotted is velocity of movement across the stroke and nothing else !
Now that I'm aware of this i have some doubt in its abiliity for flight it may be more useful in water were symmetry and a curved path is good !
....onwards
regards
Craig
Sometimes it is difficult to make and measure mechanical movements if you don’t have the proper instrument.
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Old Feb 08, 2013, 03:46 PM
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Don't give up Craig, have a look at slow motion hummingbird flight... I see nothing but extremely rapid reciprocating motion combined with a straight triangular wing that is fixed to the body at one point at its base.

Update: My Rostock Max 3D printer will be arriving this week, 50m of openbeam extrusion will be arriving the week after that and I'm ordering a 780kg milling machine out of Taiwan after the Chinese new year celebrations end which I will be converting to a steel cutting cnc beast. Hopefully within 6 months I'll be making rigs as pretty as craig and kjell.

Hopefully I'll quickly get the hang of the 3D printer and make my own variable swash drive before mid march when I go back to work for the winter.

One last thing Craig, most of what wikipedia says about how flight works is misleading, over-simplified or wrong. Just stick your hand out the window of your moving car to experiment with airfoil shapes and you'll find that the airfoil shape doesn't effect lift even ten percent as much as pitch. What I'm trying to say is that you shouldn't let anybody elses flight theory stop you from doing imperical tests. There are as many ways to fly as there are creatures that do so.
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Old Feb 09, 2013, 01:40 AM
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Gday

Don't get me wrong i'm not giving up, just a few doubts as to wether the symmetrical path is adequate to produce and efficient thrust & lift. But yes i totally agree if it can turn at humming bird speed, like 0 to 50 CPS (Cycle per second) = 0 to 3000rpm.... its gonna work.
Anyway i figured out the pitch path in the end and as it turns out stroke velocity and pitch path are totally different...took me a while but that penny has finally dropped

What instruments did you use Kjell when you plotted out the wiggle ?
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