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Old Sep 20, 2012, 03:20 PM
JWs are Shear Fun!
Aerogance's Avatar
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The birds are tacking upwind, not flying straight upwind. Look closer.

In the first segment the bird is seen flying up and down the crests and troughs. The seas appear to be around 6 feet or more. The bird zig-zags his pattern at times to stay near the boat. Turns are clearly less than 180 degrees like we do in gliders.

The second bird tipstalls a few times momentarily (pointy wingtips!).

Quite amazing how effortless it looks for the birds to maintain the pattern. But the birds are correcting for terrain constantly.

Pelicans and sea gulls will slope soar the front of swells. I imagine the Albatross can you use that technique if it has a following sea. But the upwind potential of the Albatross' technique is simply amazing.
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Old Sep 20, 2012, 03:49 PM
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Thanks for reposting, I enjoyed rewatching.

The big thing will be to do it at all, under ideal conditions. The hope is to eventually do it as well as the albatross under any flyable conditions. Birds, in one form or another seem to have been around for 150 million years. I expect it will take a while before anything man made flies as well as them.

I'm gonna google a bit and see if I can find out the L/D of the Wandering Albatross.

Pete
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Old Sep 20, 2012, 04:04 PM
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Found this:

http://esoaring.com/albatros_presentation_esa.pdf

Dunno how accurate this is but he reports the L/D as 27

Pete
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Old Sep 20, 2012, 04:34 PM
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Ya, that's Phil's paper that sort of got this ball rolling. I wonder how much of his calculation
for the albatross's L/D accounts for all the time spent in ground effect, where L/D increases dramatically.

ian
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Old Sep 21, 2012, 06:28 AM
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The attribution is J. Philip Barnes.

http://www2.esm.vt.edu/~rkriz/classe...micSoaring.pdf
By Mark Denny gives an L/D of 25

Both values look high to me. I vaguely remember a study that measured the L/D at 22.
I can't remember the source or the methods. I'd be most curious to know what the best RC model L/D's are.

Pete
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Old Sep 21, 2012, 06:44 AM
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Ah! Swiped from Wiki, but I couldn't find who wrote it.

http://en.wikipedia.org/wiki/Wandering_Albatross

"The Wandering Albatross has the largest wingspan of any living bird, typically ranging from 2.51 to 3.5 m (8 ft 3 in to 11 ft 6 in), with a mean span of 3.1 m (10 ft 2 in) in the Bird Island, South Georgia colony and an average of exactly 3 m (9 ft 10 in) in 123 birds measured off the coast of Malabar, New South Wales.[3][8][9] The longest-winged examples verified have been about 3.7 m (12 ft 2 in).[9] Even larger examples have been claimed, with two giants reportedly measuring 4.22 m (13 ft 10 in) and 5.3 m (17 ft 5 in) but these reports remain unverified.[9] As a result of its wingspan, it is capable of remaining in the air without beating its wings for several hours at a time (travelling 22 m for every metre of drop)."

Note the last sentence in parenthesis.

There is a second article that gives the same figure.

http://en.wikipedia.org/wiki/Albatross

Pete
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Old Sep 21, 2012, 03:10 PM
JWs are Shear Fun!
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So again, its the pilot and not the equipment that makes the difference!

22:1 glide ratio is not that bad considering that the fuselage is a full-functioning living animal. And at 22:1, the craft is self-replicating. We could only wish for this capability in our favorite gliders.
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Old Sep 23, 2012, 01:24 AM
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Quote:
Originally Posted by Aerogance View Post
So again, its the pilot and not the equipment that makes the difference!

22:1 glide ratio is not that bad considering that the fuselage is a full-functioning living animal. And at 22:1, the craft is self-replicating. We could only wish for this capability in our favorite gliders.
The Schweitzer 2-22 has an L/D of 14/1 and it's the first glider I did an hour flight in. The 1-26 has an L/D of 23/1 and some spectacular flights have been done in them.

I'd love to know the L/D's of high performance gliders in the 1.5 to 4 meter range is.

I'd be a bit worried when we get electro mechanical devices that can self replicate. I'm not quite ready to sign up for a lifetime stint on Battlestar Galactica.

With more intelligence being crammed into smaller devices things like autonomous DSing UAV's become feasible, but we are overlooking the possibility of having the intelligence elsewhere. Whether the situation analysis and response is on board or twelve thousand miles away does not make any diff if the link is direct and not via satellite or repeaters.

Maybe Woods Hole has a supercomputer that can speed up the thinking until the software is refined enough to run onboard. Just an idea in case stuffing that much intelligence into a small volume turned out to be a bottleneck.

Pete
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Old Sep 25, 2012, 08:50 AM
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The possibility of UAV's using dynamic soaring was also studied extensively in the following Sandia paper published in 2002:

Autonomous Dynamic Soaring Platform for Distributed Mobile Sensor Arrays, by Mark B.E. Boslough.

They explore computer simulation of the dynamic soaring process and perform RC glider testing (but on land only!)
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Old Sep 26, 2012, 12:14 AM
JWs are Shear Fun!
Aerogance's Avatar
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I read the paper. Joe Wurts was involved, and the data logged looks eerily similar to the output from Alan's telemetry system. Fascinating!
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