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Old Aug 09, 2012, 04:54 PM
UberZogster is offline
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Be the duck. Whaaaa?
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Humm bird scaring.... We have a seagull problem at work, maybe I could get paid to fly something like this around to scare them off.
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Old Aug 09, 2012, 05:41 PM
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Quote:
Originally Posted by DownUnderPilot View Post
Fantastic project! With the videos I've seen so far, there didn;t look to be much Dutch roll? How do real birds avoid this?

If someone could come up with an EPP version, they would sell extremely well IMO.
Ill be the FIRST one in line.
Old Aug 09, 2012, 05:50 PM
Lil Stinkpot is offline
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Egads! It's a GIRL!
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I think birds would feel the roll start to happen and with the flick of the "wrist" correct it before it becomes a problem. All it would have to do is lean toward the wing that is rising.

V2, put me in line for a copy, if you would. I'll also happily wait for the final version wing, while playing with a built-up version. What eyes are you going to use? I assume from a taxidermy supply shop?

BTW, if I haven't already said, this is beautiful work you are doing.
Old Aug 09, 2012, 06:18 PM
kcaldwel is offline
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Advancing the Schmilblick!
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Quote:
Originally Posted by DownUnderPilot View Post
Fantastic project! With the videos I've seen so far, there didn;t look to be much Dutch roll? How do real birds avoid this?

If someone could come up with an EPP version, they would sell extremely well IMO.
Dutch roll can occur when the ratio of lateral stability to directional stability is too large. If you have very low directional stability with no aft vertical surface, you need to have low lateral stability - or an active stability system like birds have! You can lower the lateral stability by reducing the dihedral or adding anhedral; removing aft sweep in the 1/4c of the wing or introducing forward sweep; raising the CG position relative to the wing; and/or adding a yaw damper if there is yaw control available.

In the last German video linked, the model appears to have some anhedral and a transparent fin and rudder, so it would not be likely to have Dutch roll issues (low lateral stability/significant directional stability). The Japanese models look like they have no wing sweep and no dihedral, so they would have very low lateral stability as well as low directional stability. Those combinations are unlikely to have Dutch Roll problems.

Birds fly with pitch unstable CG positions, and have no trouble dealing with that. Dutch Roll is unlikely to be a problem for them.

Cool project! I just had another eaglet fledge from behind my house. I love watching them soar on the ridge in front.

Kevin
Old Aug 09, 2012, 06:32 PM
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2012 NZ Speedcup - 231 MPH
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Ok... I wonder if one of the flight stabilisation systems (eagletree or FY30A etc) would assist here? I.e. allow the model to be more bird like whilst maintaining control?
Old Aug 09, 2012, 06:59 PM
kcaldwel is offline
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Advancing the Schmilblick!
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I've got an Eagle Tree Guardian on it's way to try. You still need some form of yaw control for a yaw stabilizer to work.

Herk Stokely has been having success without any vertical or stabilizer:

https://www.rcgroups.com/forums/show....php?t=1654485

https://www.rcgroups.com/forums/show....php?t=1699318

Kevin
Old Aug 09, 2012, 07:17 PM
V1VrV2 is offline
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Mongo like wind. Wind Good.
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Wow!

All this interesting stuff coming out of the woodwork!

The project bird I am working on can be either a Bald Eagle or Golden Eagle. The supplier of glass eyes (eagle specific and correct) makes both types. Attached are pix of both types.
Old Aug 09, 2012, 07:38 PM
V1VrV2 is offline
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Mongo like wind. Wind Good.
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Heres some pictures of the Golden Eagle.

The Golden eagle is Mexico's national symbol and North America's largest Bird of Prey (source: National Geographic)
Old Aug 09, 2012, 07:47 PM
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I am really learning something from you guys. That bit of new info is actually up my ally. I want to find a way to eliminate the rudder for a more natural (bird) look.
Old Aug 09, 2012, 09:03 PM
Weinig is offline
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Pterasaur builder
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Eagle Glider


Here is one I built from a Jack Edwards plan, no vertical cheaters. flys well.
Eddie the Eagle Glider (3 min 21 sec)
Old Aug 09, 2012, 09:55 PM
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I have always liked that video ever since I stumbled a a crossed it some years back. Great job Weinig.
Old Aug 09, 2012, 11:21 PM
Lil Stinkpot is offline
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Egads! It's a GIRL!
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Ooooh, I would just love to paint up an immature golden. They are soo pretty!
Old Aug 10, 2012, 06:57 AM
samwei1950 is offline
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DIY Mania from Taiwan
Quote:
Originally Posted by kcaldwel View Post
Dutch roll can occur when the ratio of lateral stability to directional stability is too large. If you have very low directional stability with no aft vertical surface, you need to have low lateral stability - or an active stability system like birds have! You can lower the lateral stability by reducing the dihedral or adding anhedral; removing aft sweep in the 1/4c of the wing or introducing forward sweep; raising the CG position relative to the wing; and/or adding a yaw damper if there is yaw control available.

In the last German video linked, the model appears to have some anhedral and a transparent fin and rudder, so it would not be likely to have Dutch roll issues (low lateral stability/significant directional stability). The Japanese models look like they have no wing sweep and no dihedral, so they would have very low lateral stability as well as low directional stability. Those combinations are unlikely to have Dutch Roll problems.

Birds fly with pitch unstable CG positions, and have no trouble dealing with that. Dutch Roll is unlikely to be a problem for them.

Cool project! I just had another eaglet fledge from behind my house. I love watching them soar on the ridge in front.

Kevin
Very educational,a good learning too
all the Japaness finless models made by Kanai-san have no dihedral as mentioned on his plans
regards
Sam
Old Aug 10, 2012, 09:16 AM
Lil Stinkpot is offline
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Egads! It's a GIRL!
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Are Kanai-San's plans available?
Old Aug 10, 2012, 11:43 AM
samwei1950 is offline
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DIY Mania from Taiwan
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Originally Posted by Lil Stinkpot View Post
Are Kanai-San's plans available?
See page 2 of the thread
Sam


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