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View Poll Results: Please help name this glider
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Old Feb 28, 2011, 11:38 PM
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Don Stackhouse's Avatar
United States, OH, Bradford
Joined Jun 2005
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They're called your Gluteus Maximus muscles. They're much larger in humans than in other primates because we walk upright instead of on all fours, and the "glutes" help hold us upright.

http://en.wikipedia.org/wiki/Gluteus_maximus_muscle
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Old Mar 01, 2011, 10:11 AM
cq cq de kr4is
flexsphincter's Avatar
USA, VA, virginia beach
Joined Jan 2011
277 Posts
do you guys use these wing rods on steroids for all your builds? seems like over kill for i can barely flex this rod with my bare hands and im in construction,,,,seems to me the nylon bolts would shear/pull out or the blocking for bolts would pull out b4 the wing folded up...or am i being nieve. ill order it and one for the ollyIIs im waiting for if replacing the is rod the norm. just asking
jeff
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Last edited by flexsphincter; Mar 01, 2011 at 10:21 AM.
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Old Mar 01, 2011, 10:52 AM
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Don Stackhouse's Avatar
United States, OH, Bradford
Joined Jun 2005
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Depends on the plane. The wing rod has to be strong enugh for the loads applied to it. For an open class airplane that has to be tolerant of winch launching, that means being able to handle about 300 pounds of winch line tension.

That means each wing is carrying about 150 pounds, centered about 40% of the way out from the root, so on a 10 ft. span airplane that's a bending moment at the root of about 3600 in-lbs. If you have a 1/2 inch diameter joiner, stress = Mc/I, where M is the moment, c is the distance from the neutral axis to the outermost fiber (so half the diameter, or 1/4" in this case), and I is the section modulus. For a round rod:

I = (Pi * D^4)/64 which in this case is 0.00307

Plugging all of that into our equation, we get:

stress = 3600 * .25 / .00307 = 293,000 PSI

which would require a hardened alloy steel with a hardness of about 55 Rc or better, which means heat-treated tool steel. Some of the ejector pins in the previous posts are that strong, some are not. Music wire, particularly piano wire, is that strong and hard (which is why it can put nice little dents in tool-steel diagonal cutters), but good luck trying to find some 1/2" piano wire!

If all you plan to do is high-start or electric, you can get away with less.

It all depends on what you plan to do. If you are going to apply a certain load to a part, then that part must be strong enough to handle that load.
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Old Mar 01, 2011, 11:50 AM
Unrepentant Paragon addict
LVsoaring's Avatar
United States, OK, Moore
Joined Jan 2006
2,543 Posts
Nylon bolts are incredibly strong in tension, but are designed to shear relatively easily, thus preventing damage to your wing. As for seeming like they would pull out of the mounting blocks with such a heavy load, somebody explained that to me once, but I can't remember how it goes. But basically, the load is the weight of the fuse on the wing times any g-load, or extra load imposed by a winch or hi-start. Not nearly enough to cause structural failure..... unless you really try!
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Old Mar 01, 2011, 03:19 PM
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John Cole's Avatar
Peoria, AZ
Joined Jun 2001
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Another Bird of Time emerges.

Just a bit over 40oz., too light I reckon. But I'm already thinking of ways to add ballast. Build info in Sailplane Talk, LISF BOT one-design thread.

It's a fun glider.

John
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Old Mar 01, 2011, 03:30 PM
life long racing nut & modeler
granada don's Avatar
Granada Hills Ca.
Joined Nov 2009
1,881 Posts
Hi John

Very clean build job i like your set in rudder and hindge pin , i put a set up like that on my Goose in the avatar pic works well and looks good too.

Don
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Old Mar 01, 2011, 07:02 PM
ein flugel schplinterizer
seanpcola's Avatar
USA, FL, Pensacola
Joined Sep 2004
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John,

That really is a fantastic looking BOT! Love the fuse.
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Old Mar 01, 2011, 07:11 PM
ahh crap! crunch..
atmosteve's Avatar
Australia, QLD, Fraser Island
Joined Nov 2007
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What a fuse! nice to see originality.

She looks a peach.
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Old Mar 01, 2011, 08:55 PM
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John Cole's Avatar
Peoria, AZ
Joined Jun 2001
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Thanks you guys. I've only got a few flights so far, still getting the feel of it.

Don, I've always liked the hinge pin idea too. Rudder removal is very easy as well.

John
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Old Mar 01, 2011, 09:01 PM
ein flugel schplinterizer
seanpcola's Avatar
USA, FL, Pensacola
Joined Sep 2004
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John,

I like the rudder hinge setup too. I use pins too but can you elaborate on the retention system? I can't tell in the photo but is the retainer soldered into the tail skid? I just can't make out the details. Probably my eyes ain't what they used to be.
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Old Mar 01, 2011, 10:16 PM
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John Cole's Avatar
Peoria, AZ
Joined Jun 2001
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Hey Sean,

Here ya go, these pictures may help. I flattened a short piece of alum tube, wire hinge has a folded-over prong that inserts. It has lots of friction, but I dabbed on a bit of glue for peace of mind.

The skid wire inserts into a seperate nylon tube. It's held in place w/ friction too. The top rudder pin is glued into the fin, shaped like an inverted 'U'.

Hope this helps.

John
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Old Mar 02, 2011, 06:13 AM
ein flugel schplinterizer
seanpcola's Avatar
USA, FL, Pensacola
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Ahhhhh! Got it! Thanks John! I shall now steal that idea on my next project.
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Old Mar 02, 2011, 07:02 AM
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Don Stackhouse's Avatar
United States, OH, Bradford
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What keeps the U-shaped pin from wagging side-to-side around its forward end?
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Old Mar 02, 2011, 07:03 AM
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John Cole's Avatar
Peoria, AZ
Joined Jun 2001
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Sean,

I've also 'borrowed' ideas from others too, and these threads always have good tidbits, if not just entertaining.

I mess around with WW1 scale stuff, and this quote applies there big time, but perhaps with most areas of this hobby:

"Stealing from one is plagiarism, stealing from many is research." anon

John
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Old Mar 02, 2011, 07:05 AM
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John Cole's Avatar
Peoria, AZ
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Quote:
Originally Posted by Don Stackhouse View Post
What keeps the U-shaped pin from wagging side-to-side around its forward end?
Hi Don,
The flattened alum tube keys the prong into position. The fit is quite snug.

If you meant the top pin..the top 'U' pin inserts about 3/4" into the fin and is epoxied in place. Part of the 'U' is also bonded to the tip of the fin.

John
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Last edited by John Cole; Mar 02, 2011 at 07:10 AM.
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