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Old Apr 21, 2007, 10:14 AM
PNF
infopimp's Avatar
Los Gatos, CA
Joined May 2005
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Why not mega beefy layups for leadsled wings?

Planning my layup for the twisty-Jart, I have this sick (?) idea for the layup... something like:

0.75 oz veil (45 degree)
4.1 oz unicarbon (90)
8.95 oz glass (45?)
foam

Curious, is there a downside to making wing super beefy like this? It seems most people don't go this far... but I already have a 51 oz EPP Jart and am fine going heavier considering the local slopes. This layup would add... what... 6 oz to the wing weight?

Crazy? Downsides other than weight?

-s
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Old Apr 21, 2007, 10:29 AM
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AndreasMergner's Avatar
USA, NY, Albany
Joined Dec 2003
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It will never fly that way.

I have a new 60" plane that has 45 oz wings.

If you think about it, a plank or flying wing has a really heavy wing for the weight of its fuselage and they do fine.
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Old Apr 21, 2007, 10:55 AM
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Southern California
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There are a lot of Fermin Sleds built heavier than this that fly well. Go for it!
T
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Old Apr 21, 2007, 11:03 AM
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Sensiblenick's Avatar
Sweden: Ystad
Joined Oct 2004
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It makes perfect sense actually.. You WANT weight, so shove it in the wings and get strength as an added Bonus.

Not only that... but the wings will support thier own mass... reducing the stresses in the airframe by spreading the mass thoughout the plane
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Old Apr 21, 2007, 11:07 AM
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Warwickshire, England
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does it make a difference to roll rate?

just curious.......
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Old Apr 21, 2007, 11:12 AM
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BeeDee's Avatar
Fallbrook, California, United States
Joined Jul 2003
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yeah, the roll rate will suffer if you have the mass towards the tips... also tip stalls are more pronounced with weight in the tips.. oh and can you say "Snap Roll" ??


BD
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Old Apr 21, 2007, 11:13 AM
F3B
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i see. I was imagining that you would get a high roll rate with a lot of weight in the middle and not much on the outside.
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Old Apr 21, 2007, 11:17 AM
Vitruvian JART
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San Francisco
Joined Mar 2003
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All good points here. The heavier the wing the more inertia you get out where you ordinarily don't want it - BUT, if this is to be a lead sled timmig has it right: plenty of sleds are built with heavier layups than the one you describe, Steve. In fact, I'm working on a double carbon (2x5.7oz) wing right now. For big, smooth, ballistic halfpipes, your layup will be fine.
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Old Apr 21, 2007, 11:27 AM
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USA, CA, La Mirada
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Your best bet is to layoff so much glass and build your wing with sheeting and a hardwood LE. In my first sled wing layups with Bluffman and Slopeiron we found that regardless of how heavy you layup glass over a bare foam core (even with carbon) once the LE is comprimised it wont be long before cracks and delam start growing towards the TE. We tried to compensate for this with more glass but it still didnt help. One wng we did was 3 layers of 8 ounce cloth. Now we build are wings with plywood sheeting and hardwood LE then we bag them to seal them up and provide a nice surface for painting. I have detailed the process as best I can here http://www.rcgroups.com/forums/showthread.php?t=649145
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Last edited by RMD72377; Apr 21, 2007 at 11:33 AM. Reason: unfinished post
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Old Apr 21, 2007, 11:48 AM
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Southern California
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Robert's right--- the "conventional" build with glass over that is far stronger than foam/glass/carbon!
FWIW
Tim
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Old Apr 21, 2007, 12:16 PM
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Bellevue WA,
Joined Dec 2003
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My R3 wing will come in at about 31 to 32 oz. My layup was a layer of 5 oz S glass and a layer of 3 oz e glass. I used way to much epoxy which added at least 3 oz extra weight to the wing.
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Old Apr 21, 2007, 12:30 PM
Vitruvian JART
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San Francisco
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Quote:
Originally Posted by timmig
Robert's right--- the "conventional" build with glass over that is far stronger than foam/glass/carbon!
FWIW
Tim
True in my experience as well. Ply has great properties and it's cheap! Chunky LE's help as well. I still go for the all-composite experience most of the time because I don't have rocks and I don't fly much heavy formation.
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Old Apr 21, 2007, 01:17 PM
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United Kingdom
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your roll rate will be, as they say 'adequate' - the heavy lay up makes for a heavy aeroplane which flies faster and rolls like a bag full of rolly things
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Old Apr 21, 2007, 01:48 PM
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Warwickshire, England
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I wasn't suggesting it was a bad ideal because of slow roll rate. I was just wondering how the physics work out in the real world. I'm afraid I don't have anything in that category. Yet!
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Old Apr 21, 2007, 02:50 PM
Vitruvian JART
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San Francisco
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Quote:
Originally Posted by satinet
i see. I was imagining that you would get a high roll rate with a lot of weight in the middle and not much on the outside.
Yep, your intuition is correct. Better flying characteristics all around.
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