Dragonflies and Damselflies

ISv

"The equipment that matters, is you"
Apr 30, 2017
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After little bit more digging: http://www.dragonflypix.com/speciespages/orthetrum_albistylum_en.html
I'm pretty sure there are more differences but this was what first got my eyes looking in the photos in Wikipedia. With the link above one can look for more.
I love this forum by many reasons but may be the learning photography and in the same time expanding my knowledge of the living around* stuff is the most important for me.
* - unfortunately I don't have any of these two species of dragons on the Island:)!
 
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Maximilian

The dark side - I've been there
Nov 7, 2013
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Sorry Maximilian but I think it's the Black-tailed Skimmer:unsure:! Great shots anyway!
See the locally highlighted spot: in the Black-tailed it is black (like in the Maximilian's photo). In the White-tailed it should be white!
Hi ISv!
You are right. I am always thankful if someone can teach me something I didn't know. Since this post I was and still am wondering what species this is.
Seeing this pic in the english wiki I am absolutely with you and I now see this as settled. YES!

My classification book shows a individual with a different black tail. Maxbe they got fooled by an old black tailed female that could look like this.
And after reading the description of the white tailed again I realise that I got fooled by not reading properly. Not only the female, but also the male have these white tail. The female in addition also has a white 10th abdomen segment.
 
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Maximilian

The dark side - I've been there
Nov 7, 2013
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...
I love this forum by many reasons but may be the learning photography and in the same time expanding my knowledge of the living around* stuff is the most important for me. ...
Same here :)

Thanks to all of you.
 

AlanF

Stay alert, control the camera, save photos
Aug 16, 2012
6,694
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See the locally highlighted spot: in the Black-tailed it is black (like in the Maximilian's photo). In the White-tailed it should be white!View attachment 191021
The Whitetailed Skimmer is so very similar to the Blacktailed apart from that white spot. Here is another Blacktailed taken with the 5DIV at 560mm with the DO.
2B4A0852-DxO_blacktailed_skimmer_side-lsss.jpg
 
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SteveC

M6 mk II
Sep 3, 2019
872
662
In a stationary turn (without any sideslip or change of altitude), the load factor is solely dependent of the bank angle. Speed is not involved at all. Turn rate and turn radius depend on both speed and load factor
View attachment 191006
View attachment 191007
Yep, absolutely correct.

But do note the assumptions--the lack of sideslip and no change in altitude.

If there is no change of altitude, then the plane's vertical force is one G. The G force felt by the plane (and pilot) is along the diagonal line. The horizontal component actually causes the turn. But you don't need to know the horizontal component if you know the vertical component (1 G) and the angle; from that it's easy to get the length of the diagonal line in relation to the vertical one.

If you're doing a 60 degree bank, you will experience 2G in the plane, because at that angle the diagonal line is twice as long as the vertical line.

And yes, a 90 degree bank is impossible because the vertical component will be zero (and if you push on that you end up with a divide-by-zero, which ONLY Chuck Norris can do).
 

privatebydesign

Would you take advice from a cartoons stuffed toy?
Jan 29, 2011
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But do note the assumptions--the lack of sideslip and no change in altitude.

And yes, a 90 degree bank is impossible because the vertical component will be zero (and if you push on that you end up with a divide-by-zero, which ONLY Chuck Norris can do).
Another huge assumption in the calculation by Erik X is the fact that dragonfly wings are not fixed so assuming a bank angle from a still image is extremely problematic. Plus, of course, the fact that dragonflies can hover so changes in pitch angle and g force can be as low as that change in angle.

As for the 90º bank, that is not limited to Chuck Norris as anything in free fall can attain a 90º (or any other angle) of bank which just illustrates the impracticality of deriving a G force loading from a single still image without any other data.

Example real world image of high bank angle and zero G.

14710827938_beaa78d04b_b.jpg
 
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Erik X

EOS RP
Jul 26, 2013
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Sweden
Another huge assumption in the calculation by Erik X is the fact that dragonfly wings are not fixed so assuming a bank angle from a still image is extremely problematic. Plus, of course, the fact that dragonflies can hover so changes in pitch angle and g force can be as low as that change in angle.
My conviction, not only assumption, is that dragonflies can't produce (any significant) horisontal thrust sideways. I would be delighted to see some evidence that I am wrong. :p Consequently, dragonflies must have the wings horisontally in a stationary hover.
A 90 degree bank is fully possible if vertical acceleration or sideslip is allowed, just look at the "hammerhead" or "knife edge" aerobatic manouvers.. But I'm quite sure a dragonfly can handle 80 degree / 5.7g without any problems judging from their incredibly fast turns..
 
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privatebydesign

Would you take advice from a cartoons stuffed toy?
Jan 29, 2011
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My conviction, not only assumption, is that dragonflies can't produce (any significant) horisontal thrust sideways. I would be delighted to see some evidence that I am wrong. :p Consequently, dragonflies must have the wings horisontally in a stationary hover.
A 90 degree bank is fully possible if vertical acceleration or sideslip is allowed, just look at the "hammerhead" or "knife edge" aerobatic manouvers.. But I'm quite sure a dragonfly can handle 80 degree / 5.7g without any problems judging from their incredibly fast turns..
I am quite sure they can handle that kind of loading, that wasn't my point, my point was from a single still image with no other data it is unwise and almost certainly inaccurate to put a figure on.

As for side loading, well they can flap their wings independently so if they stopped one side pair of wings and used the other side pair they could generate (for a dragonfly) a significant amount of non horizontal thrust, in a still image this would look like an extreme bank but wouldn't involve much in the way of g force.
 

SteveC

M6 mk II
Sep 3, 2019
872
662
Another huge assumption in the calculation by Erik X is the fact that dragonfly wings are not fixed so assuming a bank angle from a still image is extremely problematic. Plus, of course, the fact that dragonflies can hover so changes in pitch angle and g force can be as low as that change in angle.

As for the 90º bank, that is not limited to Chuck Norris as anything in free fall can attain a 90º (or any other angle) of bank which just illustrates the impracticality of deriving a G force loading from a single still image without any other data.

Example real world image of high bank angle and zero G.

View attachment 191043
But that involves a change in altitude.

(And furthermore, an accelerating change in altitude...what I said earlier could also apply to a turn with a change in altitude, provided the rate of change of altitude is constant--which for a falling diver, it isn't until they reach terminal velocity.)
 

Maximilian

The dark side - I've been there
Nov 7, 2013
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Now I'll have to be careful after our discussion about black-tailed versus white-tailed skimmer.

Because I also have scarce chasers (libellula fulva) in my territory:
(look at the blue eyes and at the wing tips, far away, heavy cropping, so some loss in detail)

scarce_chaser1.JPG
 
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Maximilian

The dark side - I've been there
Nov 7, 2013
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To all of you beeing frustrated trying to get some dragonflies in flight (DIF) here's a sequence how the majority (> 90%) my attemps look like.
These are mating black-tailed skimmers. They seem to be even faster in flight than the individual and I am 100% sure they were in focus when I started firing and I was so satisfied to get those shots until I looked at the results :cry:
Some 4 out of 25

So don't get frustrated, keep on trying and have fun just watching those artists of flight ;)

skimmers_mating2.JPG


skimmers_mating1.JPG skimmers_mating2.JPG skimmers_mating3.JPG skimmers_mating4.JPG
 
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