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Old Oct 10, 2012, 12:20 PM
Wood Chucker
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USA, TX, Allen
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Quote:
Originally Posted by Mark Miller View Post
OK it's on the site. Look under Models/Sailplanes. I have 6 parts sets but have to put them in the box as orders come in.

Mark
www.isthmusmodels.com
W00t!

In looking at this again I have a few questions. The site says it's a 3-piece wing which is very handy of course. I also see some comment from long ago about a winch-resistant wing. Could I follow the lead with other 2M designs and put carbon caps on the spars, maybe wrap them with kevlar to add some resistance to lead-foot? Would it make sense to build it as a single piece wing for winch resistance or would a 3-piece wing still fit the bill? I ask this largely from my experience with the DJ Aero Chrysalis 2M. It's pretty dang strong with just carbon spar caps on the center section but I do have a 1 piece wing as well.
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Old Oct 10, 2012, 01:10 PM
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United States, WI, Waunakee
Joined Oct 2002
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Lacq,

You can do what you wish to the spar. Surely won't hurt things. You may not need to do the whole wing and just do the center panel. The last three bays of the tips do not have shear webs and I doubt need it. The shear webs on the center panel are 3/16" with a 1/4x1/8" bass spar. The shear webs that are in the tip get thinner as you get nearer the tip intil there is none in the very tip. But hey. It's your plane and you can do as you wish.

I see no disadvantage to the three piece wing. The joiner is 7/32 steel music wire. It fits into a 1/4" OD brass tube. If you can bend or break it I'd be very impressed.

Mark
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Old Oct 10, 2012, 03:49 PM
Wood Chucker
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Thanks for the input Mark!
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Old Oct 10, 2012, 07:53 PM
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As a reference, I had a Sagitta 600 that used a 7/32" rod as a joiner in the center. I winch launched it many times and never bent it. The Oly 2 with 100 inch span, joined at the center with the same size rod, bent pretty often. I seem to recall that the Gentle Lady 3 piece wing used only 3/32" rod! The load goes as the square of the span, minus tip effects, if the chord stays constant, so if your joint is at 40 percent span, the load will be much less than a third as much as at the center, given a bit of taper, as on this glider. And per the sketch on the Isthmus web site, the join looks like it's more like at 45 percent. (On the GL, it's over 50 percent, which partially explains the tiny wing rods.)

Personally, I think I'd use a significantly smaller rod, either 5/32" or 3/16".

Definitely a nice looking model. I wish people did kits like this in, say, 100 inch size.
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Old Oct 10, 2012, 08:40 PM
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The joiners are the same as what I use in the Mini Bird of Time kit at the center of the two piece wing. I could do a smaller rod or maybe use a carbon rod but it is what I had easily available and so I used it.

Mark
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Old Nov 12, 2012, 08:57 PM
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Fort Collins, CO
Joined Nov 2006
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I also really enjoyed this log and though I'm not one of the lucky ones building a Duet, I do have a question regarding the wingtips. They look a really good idea, but I can't tell by the looks here if they are solid or built up. My guess is solid, then shaped. This makes the most sense to me but looking at "copying" the idea and wondering....

Thanks,
Dale
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Old Nov 14, 2012, 12:47 PM
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solid tips. The tips and nodeblock in the parts that Jack built here were laser cut but the finalkit they are just solid balsa to be shaped. I changed to just providing the balsa blocks to save on the cost of the laser cut parts.

Mark
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Old Nov 14, 2012, 08:17 PM
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Thanks, Mark. Maybe one of these days.....This is a pretty plane and I seem to be a 2M woodie kinda' guy.
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Old Nov 24, 2012, 08:56 PM
Full Scale Better! UOHHHH!
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United States, TX, Lytle
Joined Dec 2006
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Hey guys, got my wings framed, sanded and fit, the fuselage is ready for mounting, getting the tail feathers set up, got my covering on hand, ready to finish this up!!!
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Old Jul 05, 2013, 01:42 PM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
Joined Nov 2002
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Duet Day... July 4, 2013

So, I was supposed to go to my sisters place to celebrate July 4... but stuff happens. So, instead of loading my guitar... ( my sister likes for me to sing to her... no... really!)... I loaded up my Duet and went flying. Mind you, I had been all ready to go and sing, so I was a bit distracted. I get to the field with the Xploder 3.7, the Duet, the tool/hardware box, and the transmitter case. After assembling the gliders, I was going to put out the high start... That's right... not on the list above, and not in the truck...... I was alone at the field, and decided to just give the Duet a toss or two and go home. And so, I did. I tossed it 20 - 30 times, each time trying to read the almost still air. Finally, I see a good swirl in the grass coming right for me, and I threw it... and up it went. I flew for an hour and chatted with other flyers as they arrived. Finally i was down to about 200 feet and looking for lift, when the model rolled 360 degrees, rather suddenly. With no ailerons, that's quite a feat! As the roll out completed it went up about 50 feet like it was on an elevator and the inflow wind picked up strongly. I was on my way to another 20 minutes, added to the hour I had already flown. I landed the model and disassembled both. I put everything in the truck, and decided to hang around and visit with my new friends. One asked if I had already picked up my line, to which I replied that it's still at home in the garage... Does that qualify me as a purist?

Darth Purista
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Old Jul 05, 2013, 01:56 PM
Kurt Zimmerman ≡LSF 4461≡
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Montrose, NY
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Quote:
Originally Posted by schrederman View Post
So, I was supposed to go to my sisters place to celebrate July 4... but stuff happens. So, instead of loading my guitar... ( my sister likes for me to sing to her... no... really!)... I loaded up my Duet and went flying. Mind you, I had been all ready to go and sing, so I was a bit distracted. I get to the field with the Xploder 3.7, the Duet, the tool/hardware box, and the transmitter case. After assembling the gliders, I was going to put out the high start... That's right... not on the list above, and not in the truck...... I was alone at the field, and decided to just give the Duet a toss or two and go home. And so, I did. I tossed it 20 - 30 times, each time trying to read the almost still air. Finally, I see a good swirl in the grass coming right for me, and I threw it... and up it went. I flew for an hour and chatted with other flyers as they arrived. Finally i was down to about 200 feet and looking for lift, when the model rolled 360 degrees, rather suddenly. With no ailerons, that's quite a feat! As the roll out completed it went up about 50 feet like it was on an elevator and the inflow wind picked up strongly. I was on my way to another 20 minutes, added to the hour I had already flown. I landed the model and disassembled both. I put everything in the truck, and decided to hang around and visit with my new friends. One asked if I had already picked up my line, to which I replied that it's still at home in the garage... Does that qualify me as a purist?

Darth Purista


... Son.... you best bow when you are in the presents of the Darth Purista.... He is GOD!... He is KING!

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Old Jul 05, 2013, 04:49 PM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
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Maybe I should sign out as.... Darth Luckista...
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Old Jul 05, 2013, 06:49 PM
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So sounds way too cool!!!!
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Last edited by NZ7C; Jul 06, 2013 at 11:13 PM.
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Old Jul 07, 2013, 10:50 AM
Unrepentant Paragon addict
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United States, OK, Moore
Joined Jan 2006
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Yes, you are a purist....a dam lucky purist!

Congrats on salvaging the day and an excellent flight!
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Old Jul 07, 2013, 12:23 PM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
Joined Nov 2002
7,844 Posts
Yeah... after 20 - 30 tries... is it just luck, or perseverance? Low level lift on my current field is either close to non-existent, or, I'm just gettin' old and outa practice. Probably some of both...
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