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Old Jun 04, 2012, 01:12 PM
discus.fly is online now
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Tuck Effect


Ok so moved the cog further forward, flying great hit a large thermal and then found at 1000ft I had no control!

After a few seconds regained control and started a turn to the left but then she then put her nose down and dissapeared at a great turn of speed.

Found her after an extended search. Nose was a right off, interestingly one aerial wire on the Rx was detached and the depron had fractured arround one of the tailerons.

So was this the dreaded tuck effect or not. Not sure if I had control during the dive as could not hear the motor but suspect it was a combination of Rx, Ae wire and the dreaded tuck.
Last edited by discus.fly; Jun 04, 2012 at 01:20 PM.
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Old Jun 04, 2012, 09:41 PM
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Hope its repairable.

Hard to say what may have been going on at 1k' or whether the tail fracture took place at height or because of the crash. I had a scratch built sailplane fold up flying level into a thermal/mini wind shear once. You should have dive tested for tuck lower down where you could see what was going on. Several dive tests each time picking up more speed and checking how well it responded to up elevator.

Here is something else to confuse the issue. A flat bottomed airfoil when sitting flat will have a degree or 2 of positive angle of attack. After looking at the picture of your plane [nice looking btw] I noticed that the reflex might be enough to give it a negative AoA. The motor in its current location could give it just enough pitch up to compensate for this while under power. Draw an imaginary line through the nose of the foil to the highest part of the reflexed TE and see if it is so. The decalage of the tail should be the same or up a degree.

Richard
Old Jun 05, 2012, 07:29 AM
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Damage


Had expected to find a pile of Depron but was very surprised to find an more or less intact structure with the wings still intact given that the impact was near vertical.

Wings are repairable but probably best to construct a new fueselarge using the old tail.
Old Jun 05, 2012, 08:18 AM
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Today I did maiden my EPP seagull. She flies wonderful and gentle. Span 1,75m. I just have to finish some paint.
Last edited by bluefalconhollan; Mar 03, 2016 at 02:23 PM.
Old Jun 05, 2012, 11:30 AM
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Very nice.

Looks like you have a complex aerofoil. Would be interested to know the design
Old Jun 05, 2012, 11:36 AM
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Dance the skies...
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Quote:
Originally Posted by bluefalconhollan View Post
Today I did maiden my EPP seagull. She flies wonderful and gentle. Span 1,75m. I just have to finish some paint.
What a wonderful-looking scratch-build! The spinner emulation of the beak is very clever. I'd like to see some flight video, please, as well as build details.
Old Jun 05, 2012, 12:49 PM
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Hi Robert. That looks a lot like Lee's gull wing falcon. Very nice!

Can you take some close up pictures of the wings, servo placement, and the way the wings are mounted. I've emailed you pictures of my bird but I'm still at a stand still of what I should do next. I would love more help from you if you don't mind. Thanks*
Old Jun 06, 2012, 04:05 PM
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I will ad more details later. Today I did the maiden and film the gull.

https://www.youtube.com/watch?v=WOn3Z4Ax9d4
Old Jun 06, 2012, 04:10 PM
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Quote:
Originally Posted by bluefalconhollan View Post
Today I did maiden my EPP seagull. She flies wonderful and gentle. Span 1,75m. I just have to finish some paint.
I can't compete with that level of quality!
Where is the CG on yours?
What is your power setup?
Old Jun 06, 2012, 04:15 PM
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split-tail elevons? i'm so jealous it makes me mad! hahaha! dang i gotta redo mine and get it flying.
Old Jun 06, 2012, 08:16 PM
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skumgummi dave
bluefalconhollan:

WOW!
Old Jun 07, 2012, 04:41 AM
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New 160% Eagle


Made a start cutting out a new fuselage for my 160% EPP Eagle. Any advice as to changes to make to avoid the tuck problem I have.

Currently the wing and tail are set at the same angle.
Old Jun 07, 2012, 05:47 AM
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Originally Posted by G-LO View Post
Hi Robert. That looks a lot like Lee's gull wing falcon. Very nice!

Can you take some close up pictures of the wings, servo placement, and the way the wings are mounted. I've emailed you pictures of my bird but I'm still at a stand still of what I should do next. I would love more help from you if you don't mind. Thanks*
Just finished painting. The wings are fixed to the fuselage. The camera part can come off from the fuselage so there is space for the battery. I use a wing aileron and a leading edge-ron, differential controlled.
Last edited by bluefalconhollan; Mar 03, 2016 at 02:23 PM.
Old Jun 07, 2012, 09:24 AM
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What could possibly go wrong?
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Leading edge-ron? That's a new one for me. Very interesting!

Do you mean a single servo droops the leading edge at the same time as raising the aileron panel and vice versa? What's the benefit?

Whatever it is, it obviously works beautifully.

Cheers

Nick
Old Jun 07, 2012, 09:42 AM
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Thank you very much Robert. Is there a reason why you glued the wings to the fuse as appose to making it detachable? Sorry for the questions. I'm trying move forward with my falcon. I interested in trying something new this go around.

Lastly. Do you have any suggestions based on the pictures I sent you?

Thank you.


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