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PatriciaJB
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Posted: Mon Oct 15th, 2007 02:59 pm |
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This section is for the discussion of flapping mechanisms.
This is one of my first designs [just to get the conversation started  ]. The purpose behind this design was to allow the wings to sweep forward on the downstroke .[see animation below] It is fully adjustable by varying the attachment points of the fuselage guide arm and the conrod to the wingspar so it's capable of many interesting modifications. [we started discussing this mech' on the previous forum]
I'll add more designs later .
The designs that I include here are ones that I am or have been experimenting with [ I'm very interested in all flapping mechanisms not just those that are intended for testing on Nightingale] . Depending on the test results, I may or may not actually use any of them on Nightingale and some of my experimental designs are not intended for Nightingale at all !!.
This section is for the discussion of all flapping mechanism designs.
Cheers, Patricia
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 Last edited on Mon Oct 15th, 2007 03:00 pm by PatriciaJB
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PatriciaJB
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Posted: Mon Oct 15th, 2007 03:02 pm |
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This image has a few more details.
EDIT: There is an error in this image !
The link BC is incorrectly referred to in the annotations as link BDAttached Image (viewed 842 times):
 Last edited on Mon Oct 15th, 2007 03:58 pm by PatriciaJB
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PatriciaJB
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Posted: Sun Nov 11th, 2007 07:37 pm |
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Here's John Mack's Swash Amplitude Control Mechanism.
Uses angled bearing on crankshaft with swash plate to produce the flapping motion and has fully adjustable control rod to vary the flapping amplitude.
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murray
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Posted: Wed Nov 14th, 2007 06:57 am |
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Patricia's teardrop tip trajectory constitutes a loop which, in my opinion will produce a pitch stabilising effect. Though I have not developed a quantitative model for the effective "tail volume" introduced by such a flapping loop, I expect it to be proportional to the volume of the conical shape subtended by the tip motion loop.
Murray.
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PatriciaJB
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Posted: Thu Mar 6th, 2008 08:40 am |
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Kjell wrote: Patricia.
The John Mack’s design is clever. Have you seen any working model or it is only an idea written on a paper?
Kjell
John Mack [ my good friend and ornithopter mentor] has designed, built and flown many ornithopter test models. For photo's, drawings and his design descriptions see the ornithopter researchers page on my website http://www.ornithopter-pilot.com/Ornithopter_Researchers_Forum.html
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PatriciaJB
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Posted: Thu Mar 6th, 2008 09:22 am |
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Kjell wrote: Patricia,
I can’t se any working model of John Mack's Swash Amplitude Control Mechanism.
Do you have any picture?
Kjell
No, the drawings were part of a discussion we had on the feasability of using swash plates in flapping mechanisms for a manned ornithopter. His design allowed the flapping amplitude to be varied and the wing to be locked in best glide position in the event of engine failure. We also discussed the disadvantages of using swash plates in bouncing, thrashing ornithopters eg: the necessity for 'guides' to 'hold down' the followers [ increases design complexity, weight, friction] etc.Last edited on Thu Mar 6th, 2008 09:24 am by PatriciaJB
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Kjell
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Posted: Sun Apr 6th, 2008 11:23 am |
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This a variant of Patricia’s wing mechanism.
http://www.youtube.com/watch?v=mEWzo26Pnog
Kjell
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Sigurd
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Posted: Thu Dec 18th, 2008 01:44 pm |
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here is an unsymetric planetary drive, or whatever you'd call it.
It makes reduction and rotary to linear. It can be toothed or traction (friction) drive.
If traction drive, there can be space between the sun gear and the larger (it doesn't have to be larger) planet. Then there could be a tensioner on that planet's axle, on the carrier, to adjust the traction. So there's a clutch also.
You can play with cycle speed shapes by adding a pivot at the bottom of the red stick (linear out) and adding a linkage, pivoted at both ends, from the ring gear to ground.
You could also take out linear power from the carrier.
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 Last edited on Thu Dec 18th, 2008 01:47 pm by Sigurd
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Sigurd
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Posted: Thu Dec 18th, 2008 01:46 pm |
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| If ring is pivot linked to ground, two phases can be taken out in the same direction, one from the ring and one from the carrier. Attached Image (viewed 446 times):
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Sigurd
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Posted: Thu Dec 18th, 2008 05:55 pm |
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| Or if power is taken from a planet of half the ring size, the output is straight. Attached Image (viewed 446 times):
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PatriciaJB
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Posted: Thu Dec 18th, 2008 08:19 pm |
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Hi Sigurd,
This can also be done using external gears only. I made a small model a few years ago to experiment with. [ I'm interested in this type of thing because of the variation that it's capable of] - Will post photo later tonight - have to go out now.
Welcome to the forum !
Cheers,
Patricia
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Sigurd
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Posted: Sat Dec 20th, 2008 08:19 am |
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hehe, I forgot- the above mechanism with the "straight line", is only straight relative to the ring!! 
thanks! Always interested in more flapping mechanisms..Last edited on Sat Dec 20th, 2008 08:20 am by Sigurd
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Sigurd
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Posted: Sun Dec 21st, 2008 01:36 am |
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I've been thinking about phasing mechanisms for four wings. One possibility is to extract 90 and 0 degrees ~linear for one of the wingsets, and then mix them using two locomotive valve gears, like the baker gear for instance. This would require low actuation force*distance, I think, and one would get flap amplitude in the same mechanism. But alot of linkages are required, and an extra phase for instance for incidence control requires, well, a disgusting amount of parts, I think.
There are also commercial rotary phasers, based on a similar principle as a car differential. The ones I've found were pretty heavy.
I would like to hear other ideas too.
EDIT: Don't forget the photo, patricia! I'm suspended!
Last edited on Sun Dec 21st, 2008 01:38 am by Sigurd
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PatriciaJB
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Posted: Sun Dec 21st, 2008 02:58 pm |
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Hi Sigurd,
Sorry about the delay - and the blurry photo's - my camera is not focusing properly.
This is a simplified cardan gear using 3 spur gears. The large sun gear on the left is fixed. There is an idler gear which moves around around the sun gear and an output gear which is driven by the idler [it's not touching the sun gear].
The plywood base plate is fixed to the sun gear. The top plywood plate is not attached to the sun gear and is driven by the engine crankshaft. The red dot shows the output path.
The output gear must be 1/2 the diameter of the sun gear.
The red output pin must be the same distance [d] from it's axle as it's axle is from the sun gears's axis. The output stroke will then be 4d. This is one advantage of this setup - it gives a long stroke for the size of the gears used. Another advantage is that by varying the angle of the fixed base plate , the stroke angle can be varied and yet another advantage is that there is no need for an internal gear.
Here's a few photo's of the 'quick and scruffy' model I made. I'll look up some better diagrams for you .
Cheers,
Patricia
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PatriciaJB
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Posted: Sun Dec 21st, 2008 03:00 pm |
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