HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Aug 09, 2012, 03:54 PM
Be the duck. Whaaaa?
UberZogster's Avatar
United States, CA, Guerneville
Joined Mar 2012
312 Posts
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.
UberZogster is offline Find More Posts by UberZogster
Reply With Quote
Sign up now
to remove ads between posts
Old Aug 09, 2012, 04:41 PM
Registered User
G-LO's Avatar
Va.Beach VA.
Joined Aug 2007
2,147 Posts
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.
G-LO is offline Find More Posts by G-LO
Reply With Quote
Old Aug 09, 2012, 04:50 PM
Egads! It's a GIRL!
Lil Stinkpot's Avatar
United States, CA, San Jose
Joined Jul 2011
3,321 Posts
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.
Lil Stinkpot is offline Find More Posts by Lil Stinkpot
Reply With Quote
Old Aug 09, 2012, 05:18 PM
"...certainty is absurd."
kcaldwel's Avatar
Joined Jan 2007
3,631 Posts
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
kcaldwel is offline Find More Posts by kcaldwel
Reply With Quote
Old Aug 09, 2012, 05:32 PM
2012 NZ Speedcup - 231 MPH
DownUnderPilot's Avatar
New Zealand, Tasman, Richmond
Joined Mar 2006
2,035 Posts
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?
DownUnderPilot is online now Find More Posts by DownUnderPilot
Reply With Quote
Old Aug 09, 2012, 05:59 PM
"...certainty is absurd."
kcaldwel's Avatar
Joined Jan 2007
3,631 Posts
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:

http://www.rcgroups.com/forums/showthread.php?t=1654485

http://www.rcgroups.com/forums/showthread.php?t=1699318

Kevin
kcaldwel is offline Find More Posts by kcaldwel
Reply With Quote
Old Aug 09, 2012, 06:17 PM
Mongo like wind. Wind Good.
V1VrV2's Avatar
Joined Apr 2004
424 Posts
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.
V1VrV2 is online now Find More Posts by V1VrV2
RCG Plus Member
Latest blog entry: Superhawk Build 2014
Reply With Quote
Old Aug 09, 2012, 06:38 PM
Mongo like wind. Wind Good.
V1VrV2's Avatar
Joined Apr 2004
424 Posts
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)
V1VrV2 is online now Find More Posts by V1VrV2
RCG Plus Member
Latest blog entry: Superhawk Build 2014
Reply With Quote
Old Aug 09, 2012, 06:47 PM
Registered User
G-LO's Avatar
Va.Beach VA.
Joined Aug 2007
2,147 Posts
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.
G-LO is offline Find More Posts by G-LO
Reply With Quote
Old Aug 09, 2012, 08:03 PM
Pterasaur builder
Weinig's Avatar
LaPorte IN
Joined Oct 2008
124 Posts
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)
Weinig is offline Find More Posts by Weinig
Reply With Quote
Old Aug 09, 2012, 08:55 PM
Registered User
G-LO's Avatar
Va.Beach VA.
Joined Aug 2007
2,147 Posts
I have always liked that video ever since I stumbled a a crossed it some years back. Great job Weinig.
G-LO is offline Find More Posts by G-LO
Reply With Quote
Old Aug 09, 2012, 10:21 PM
Egads! It's a GIRL!
Lil Stinkpot's Avatar
United States, CA, San Jose
Joined Jul 2011
3,321 Posts
Ooooh, I would just love to paint up an immature golden. They are soo pretty!
Lil Stinkpot is offline Find More Posts by Lil Stinkpot
Reply With Quote
Old Aug 10, 2012, 05:57 AM
DIY Mania from Taiwan
Taiwan
Joined Aug 2011
1,986 Posts
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
samwei1950 is offline Find More Posts by samwei1950
Reply With Quote
Old Aug 10, 2012, 08:16 AM
Egads! It's a GIRL!
Lil Stinkpot's Avatar
United States, CA, San Jose
Joined Jul 2011
3,321 Posts
Are Kanai-San's plans available?
Lil Stinkpot is offline Find More Posts by Lil Stinkpot
Reply With Quote
Old Aug 10, 2012, 10:43 AM
DIY Mania from Taiwan
Taiwan
Joined Aug 2011
1,986 Posts
Quote:
Originally Posted by Lil Stinkpot View Post
Are Kanai-San's plans available?
See page 2 of the thread
Sam
samwei1950 is offline Find More Posts by samwei1950
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Build Log Project "Bald Eagle" P51 Micro mod (1stVideo post 89). cabman1969 Scratchbuilt Indoor and Micro Models 129 Nov 20, 2011 05:32 AM
Bald Eagle grabbed my sloper! JWC Electric Sailplanes 15 Mar 31, 2008 11:09 PM