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Old Jan 07, 2012, 02:56 PM
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Knoll53's Avatar
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Yes, I believe that I am in good company.
From our friends at Moyes.

Kent
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Old Jan 07, 2012, 04:05 PM
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great shots Kent, thanks for posting

not sure but is this the same wing? edit- on closer inspection, no it's not is it!
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Old Jan 10, 2012, 04:41 PM
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Miniphase: Thank you for posting. That rigid wing really brings me back. Looks like an all wood framework from the early days. That flying site looks familiar. I too would like to know more about that glider. I flew hang gliders here on the coast of California back in the late 1970s and all gliders where early flex wings, except for one guy named Eagle who was building a spruce rigid wing something like your photo. I never heard whether he finished on not.
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Old Jan 10, 2012, 05:01 PM
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Quote:
Originally Posted by andrecillo76 View Post
We used also the cross spar, though.
Andrés
I'd like to think that the cross spar and the TE sub spar could be omitted if the main curved spar and D-tube were built properly. This would rely on stiff ribs to overhang back to the TE. Similar to the ATOS.

The cross spar would add a lot of strength to the main spar but would cut the sub spar and require a connection. This could be a moment resisting connection but that is hard to do and adds complexity.

This is what I like about the continuous curved sub spar. Easy to build with no connections to other spars and although it is not tied to the main spar, this long one piece spar should provide enough stiffness, working with the main through the ribs, to complete a flutter resistant design.

Besides, I like the way it looks.

I'll be bungee launching this glider at high speed so we'll get a chance to see if I got it right.

Kent
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Old Jan 10, 2012, 08:01 PM
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nmasters's Avatar
Colorado
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Quote:
Originally Posted by miniphase View Post
-edit- on closer inspection, no it's not is it!
It looked familiar to me. It's a very early Mitchell wing. Designed back in the '40s. You can see it or a later plane built from the same plans at 5:36 in this video. You might also recognize some names. I didn't realize until I saw this that Steven Morris is Australian.
Hang Ten Hang Gliding World Meet, Part 1 (8 min 27 sec)
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Old Jan 11, 2012, 07:05 AM
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Quote:
Originally Posted by Knoll53 View Post
Besides, I like the way it looks.
I like their looks too. Regarding crosspars, well , I like them in general because of several points:
  • do not add much mass behind the CG
  • strengthen the region with highest bending moments
  • bending axis oriented perpendicularly to the spar's principal axis
  • an aft joiner can be integrated very well

I'm sure your approach with the bent subspar will work perfectly. The low AR, higher sweep back, and thick airfoils suggest an intrinsic tendency to withstand flutter. There is only one way to find out

Regards,
Andrés
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Old Jan 11, 2012, 10:52 AM
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Norm: Great video, thanks. I did not recognize that early version of the Mitchell Wing. I only knew of his later wings. It looked very stable in the air. He seemed to have the "formula" even back then.

Andres: Thanks for your summation. It's amazing that you can do that in a second language. The cross spar has a near perfect location on the Manatee. It is AT the CG. Thus it is able to support the main spar at the middle of the main spar's loading.
I would think that the cross spar becomes less useful the farther away it is from the CG. Such as on a highly swept skinny wing, like the CO8. In that case, the cross spar is not only much shorter, but way forward of the CG. The analysis of the bending and moment forces at the root of the CO8 seem much much more complex. The normal main spar bending forces would be converted torque in that case. I would think that the CO8 would have rather high torsion loads at the kinked root.

regards,
Kent
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Old Jan 11, 2012, 11:42 AM
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Kent,

wow, a cross spar for the CO8 makes in my opinion no sense. It would profit more of having two spars.

"And one point more goes to Hortens" with their large chord at the center

Andrés
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Old Jan 15, 2012, 01:22 PM
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Modeling the major parts

The parts are getting modeled as solids ( as opposed to flat surfaces ), then cut files will be generated from those solids. With the solids, it is easier to check the work.

Kent
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Old Jan 15, 2012, 01:31 PM
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That's looking great Kent. I hear you about modeling in 3D with solid parts. Much easier to see that everything fits. What CAD are you using?

Mark
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Old Jan 15, 2012, 02:49 PM
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I REALLY need to get into 3D CAD. Oh, and buy a CNC router...
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Old Jan 15, 2012, 03:36 PM
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Quote:
Originally Posted by Shedofdread View Post
I REALLY need to get into 3D CAD. Oh, and buy a CNC router...
Here you go - http://sketchup.google.com/ (free) Oh, and here - http://www.phlatboyz.com/Phlatboyz-Machines_c_1.html (not so free) though in this department, there is every thing from 100% junk yard scrounged DIY to the ends of your wallet.

Mark
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Old Jan 15, 2012, 05:28 PM
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Quick: This is Rhino 3D.
Free full working demo here

Kent
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Old Jan 15, 2012, 05:39 PM
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From what I've seen (both Kent's work and that of others), Rhino really seems the way to go. OK maybe there are better packages out there but at greatly increased cost.

Hopefully this year will see the arrival of CNC kit at work. Maybe my boss'll let me use it 'after hours'. After all, he's such a decent chap
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Old Jan 15, 2012, 06:35 PM
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Although I was able to get Rhino 3D for $195, because I am a student, it would not be such a good deal if I didn't like it. Like it I do, but I've been using CAD since 1990 and compared to some of the junk I've had to suffer though, it's good.

Your experience may be different. So definitely burn some time using and testing in the demo mode which allows unlimited use but 25 maximum saves before you decide. There are definently bugs in the software which require work arounds. Surface offset and Boolean operations are not 100%.

Kent
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