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Old Nov 05, 2012, 10:02 AM
a.k.a. Matt Nelson
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North Tustin, CA
Joined Oct 2008
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Nick - nice pictures of your build. You obviously have some finely tuned skills!

I do have some comments re: joining the wings - please do not take them as criticism, as your work is very good. I have thought about the wing joint a lot in the past, and have come to the conclusion that Oleg has it figured out perfectly in his Taboo building instructions. When I sat down and thought about the forces exerted on the wing joint (tension and compression) and which materials come into play to resist them (skins, spar, splooge), I quickly converged on Oleg's joining method.

Specifically:
  • Poking holes in the face of the root joint is pointless. The foam cannot resist tension - imagine trying to pull apart a wing with only the foam faces glued together; the foam would tear out very easily. The epoxy in the root joint is there to fill any gaps between the faces to ensure that compressional forces are spread out over the entire surface.
  • Hollow-out the foam under the skin edge. If you look closely at Oleg's pictures, you can see that on each root face, he scrapes out a very small line of foam under the edge of the wing skin. When joined, this gap creates a bead of epoxy that very strongly bonds the skins together across the joint. This is very important, as the skin is one of the structural components that resists tensional forces on the joint.
  • Join the spars with a resin column. Hollow out a groove of foam between the upper and lower spars. This creates a void that will be filled by epoxy creating a structural column between the upper and lower spars - this column will strengthen the spar structure, and help prevent "buckling" failure at the root joint.

Take it or leave it - but I'm convinced that Oleg got it right.

Once again, beautiful build (I like the ball link - nicely done!). That Neos is looking better and better all the time!

-matt
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Old Nov 05, 2012, 01:44 PM
Thermal, where art thou?
BavarianCharles's Avatar
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Quote:
Originally Posted by MattN View Post
Nick - nice pictures of your build. You obviously have some finely tuned skills!

I do have some comments re: joining the wings - please do not take them as criticism, as your work is very good. I have thought about the wing joint a lot in the past, and have come to the conclusion that Oleg has it figured out perfectly in his Taboo building instructions. When I sat down and thought about the forces exerted on the wing joint (tension and compression) and which materials come into play to resist them (skins, spar, splooge), I quickly converged on Oleg's joining method.


Specifically:
  • Poking holes in the face of the root joint is pointless. The foam cannot resist tension - imagine trying to pull apart a wing with only the foam faces glued together; the foam would tear out very easily. The epoxy in the root joint is there to fill any gaps between the faces to ensure that compressional forces are spread out over the entire surface.
  • Hollow-out the foam under the skin edge. If you look closely at Oleg's pictures, you can see that on each root face, he scrapes out a very small line of foam under the edge of the wing skin. When joined, this gap creates a bead of epoxy that very strongly bonds the skins together across the joint. This is very important, as the skin is one of the structural components that resists tensional forces on the joint.
  • Join the spars with a resin column. Hollow out a groove of foam between the upper and lower spars. This creates a void that will be filled by epoxy creating a structural column between the upper and lower spars - this column will strengthen the spar structure, and help prevent "buckling" failure at the root joint.
Take it or leave it - but I'm convinced that Oleg got it right.

Once again, beautiful build (I like the ball link - nicely done!). That Neos is looking better and better all the time!

-matt
I'd like to second Matt's comments: Sand the dihedral into each panel. and then remove a small amount of foam, maybe 1/16 deep, over the entire cross-section of the root chord. A Dremel with a router bit and the router attachment makes it easy, just like it does for creating the servo pockets. Towrds the LE, just pick the foam out with a sharp pointy thing.

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Old Nov 06, 2012, 01:21 AM
SCSA - Nick Wu
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China, Guangdong, Guangzhou
Joined Apr 2009
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Thanks Matt for your great advice!

Actually it's the second bagged plane build of mine, still need to learn a lots of skills from you guys.



I've noticed Oleg's build guide as Thomas send to me, the reason why I did't hollow-out the foam under the skin edge is that I used carbon cloth on both side of the wing, (I can use fiberglass strips for the bottom side, but I just don't like what it will looks like as you need to sand the carbon surface.) I just want to save the weight, but I did't know how the enforcement works.

And the join of the spars, oh,man! I just missed that important part!!

I have make some big mistake when I build my Neos. one is I drilled the hole of the spring in a wrong way. it should be reverse. two inside the front, and one hole near the horn....

I may change the tails to a lighter set, I'm looking forward to test Thomas' new CNC tails. lol

Thanks again for your comments!

Nick
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Old Nov 06, 2012, 01:40 AM
Team Hong Kong F3K
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Hong Kong
Joined Sep 2010
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Great points Matt, totally agree. Oleg's building guide is a must-read for everything IMHO, even if you only fly mouldies, it goes through so much stuff that you'd use most of those skills eventually.

Nick, time for you to build another Neos!!
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Old Nov 06, 2012, 02:04 AM
Launch high. Fly low.
United States, CA, Lake Elsinore
Joined Aug 2003
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Thomas,

Did you try adding more dihedral with your latest build?

Jun
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Old Nov 06, 2012, 02:08 AM
Team Hong Kong F3K
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Hong Kong
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Yeah, it's at 6 degrees right now, plus slightly bigger vert and 5.X% larger stab.
Should make it fly even smoother!
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Old Nov 06, 2012, 02:20 AM
Team Hong Kong F3K
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Hong Kong
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Both planes weighted to 262 grams, ready to rock!
Also a shot of both the new and old tails
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Old Nov 06, 2012, 02:28 AM
DS Addict
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Christchurch, New Zealand
Joined Jul 2005
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I really think it is fantastic how you are developing this model continually! Great work, keep it up =)
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Old Nov 06, 2012, 03:02 AM
Team Hong Kong F3K
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Hong Kong
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Thanks Alex!
It's my goal to continue developing this model as I go along, and eventually have a version suitable for light light air, and a very finished moulded version what can be airborne in 2 or 3 hours. Each day is 1 step closer!!

Thomas
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Old Nov 06, 2012, 05:44 AM
SCSA - Nick Wu
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China, Guangdong, Guangzhou
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Quote:
Originally Posted by ThomasLee View Post
Nick, time for you to build another Neos!!

No money no talk.lol~~~
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Old Nov 06, 2012, 06:35 AM
Planes dress doors...
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Australia, QLD, Kippa-Ring
Joined Mar 2011
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Wow - those new tails just look plain sexy! Love the outline, will I get one of those? Pleeeeease
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Old Nov 06, 2012, 02:05 PM
Registered User
New Zealand, Waikato, Hamilton
Joined Jul 2011
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Quote:
Originally Posted by ThomasLee View Post
Thanks Alex!
It's my goal to continue developing this model as I go along, and eventually have a version suitable for light light air, and a very finished moulded version what can be airborne in 2 or 3 hours. Each day is 1 step closer!!

Thomas
thats what I love about it - the development. I have a few ideas on some changes - but I would need to fly the current one a lot more to see how it works out....
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Old Nov 07, 2012, 04:16 AM
Team Hong Kong F3K
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Hong Kong
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Flew for 3 hours today, mainly spent trimming the new CNC plane.
Took a few videos of the launches, but shot with a lower resolution again by accident... will cut it up and upload it in a day or two. Will shoot a better one on Sunday if possible.

Collected a sample of 10 launches on each plane, the new plane is definitely a little higher, even though it has 0.5 degrees more dihedral, and is ruddered. Both planes weighted at 262 grams.

I still cannot draw conclusions on handling, will keep flying them more.
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Old Nov 07, 2012, 08:36 AM
Team Hong Kong F3K
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Hong Kong
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Rhys, you bet!!!
Wynn, get it back in the air buddy!

Some launches from today, I can't wait to break my new PB and reach 60m!!

Neos (CNC Core) Flight Testing (2 min 10 sec)
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Old Nov 07, 2012, 10:17 AM
SCSA - Nick Wu
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China, Guangdong, Guangzhou
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0 _ 0 !

I bet you have eaten a lot of MEAT today!
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