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View Poll Results: Please help name this glider
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Old Oct 19, 2012, 02:22 PM
Laser Cutter Guy
United States, PA, Greensburg
Joined Oct 2009
250 Posts
a point not often thought about but adds great strentgth to an airframe is the tabbing and interlocking of parts. by doing this you are adding strength in shear and also contact area for joints. not to mention the ability to frame an assembly up very fast with little or no jigs.
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Old Oct 19, 2012, 03:18 PM
Making wood fly since 2007
Windependence's Avatar
USA, MN, Rochester
Joined Mar 2008
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Originally Posted by Don Stackhouse View Post
I could probably add a full-house version of the three meter Chrysalis to my list. Dunno about stretching it to more than 3 meters, not sure that's necessary. Other than that, it's already everything on your list. Only carbon in it is the joiner rods in the wing.

Still trying to get the RES version done, in between getting unpacked after moving back from Michigan, and getting settled into my new day job.
Hi Don, glad to hear you are getting back to your home in Ohio. I could live with 3 meters, the only reason I initially said 3.2 - 3.5 is that seems do be a fairly common size in the unlimited class.

Quote:
Originally Posted by seanpcola View Post
Off the top of my head:

Airfoil accuracy: It would be really hard to beat a moldie there.

AUW-Strength: Probably could be done by someone that's much better than I at building and wood selection.

Having said the above I would still say the big determining factor would be the pilot. What the woodie might lose in AF efficiency could be made up in skill.
Airfoil accuracy is important but with today's laser cut ribs it is a bit easier to get a good consistent wing. Also a fully wood sheeted wing would help out there. No covering sag to worry about but you do have to figure out how to properly support the sheeting without using foam.

Wayne
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Old Oct 19, 2012, 03:37 PM
Making wood fly since 2007
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Originally Posted by Lil Stinkpot View Post
A butternut veneer? I would soooo varnish that sucker.
Butternut veneer has virtually the same specific gravity as obechi but it is cheap and easy to get. It also looks like Walnut so it would make for a stunning wing. Why not use that for wing sheeting? It also takes stain very nicely so you could stain or dye the underside of the wing dark without needing to paint it. If you wanted to add colors simply use water based poly with some coler dye added.

Wayne
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Old Oct 19, 2012, 03:42 PM
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United States, AZ, Scottsdale
Joined Jul 2011
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I just took a gander at the ribs in my OLY III kit last night....man they are beautiful,and thin....I bet you could double or triple the amount of ribs with-out much extra weight to support sheeting. I'm just getting the hang of my refurb OLY III RES, I will build my new Oly with flaps as the next progression in my learning. It is a slick looking ship for a woody...
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Old Oct 19, 2012, 03:51 PM
Good, fast or cheap, pick two
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Napa, California
Joined Jul 2006
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Mr. Smith... I'm in the midst of an Oly II SX build and am just about to start the wings. I'm seriously considering adding flaps and bailing on the spoiler idea. I don't know, I think I prefer ships with flaps more than spoilers for some reason. I'm not exactly sure why, but the few planes that I've had with flaps I like more -maybe it's the ability to add a little camber/reflex if needed? I'll let you know which way I go, when I get there!

Cheers,

Rob
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Old Oct 19, 2012, 04:09 PM
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United States, OH, Bradford
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Quote:
Originally Posted by seanpcola View Post
...
Airfoil accuracy: It would be really hard to beat a moldie there....
Yes and no. Martin Hepperle has an article on the effects of covering sag. At low Reynolds numbers the turbulating and straightening effects can actually be beneficial.

On the Chrysalis series designs, I measured the covering sag, and noted that roughly 80-90% of the surface in between the ribs is at about the same airfoil shape, just not the same as the shape at the ribs. I then came up with "corrections" to the rib shapes to lift that surface in between the ribs up to the nominal airfoil shape. It was a HUGE amount of extra work (several individual segments of each individual rib that each had a different correction factor), but it paid off in the end results, excellent performance without having to use D-tube sheeting (something beginners often have trouble with).

If you look closely at a Chrysalis wing, you can see from reflections on the covering that there is no "kink" in the covering where it crosses the spar, unlike most open-framework wings.

We did have a case or two of folks mistakenly trying to D-tube sheet the wings. It hurt the performance and handling.
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Old Oct 19, 2012, 04:15 PM
Dragons, Windmills. All Same.
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United States, IN, Indianapolis
Joined May 2002
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I found this interesting along with some products I was not aware of.
12 minute vid from Joe the carpenter,
http://www.woodworkersjournal.com/re...lue/index.html

Jared
Rats, I have not had a black light since the late 60's
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Old Oct 19, 2012, 05:12 PM
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Rob,

The big Oly III likes to move out, I think the flaps would be great on it for landing, etc. I think the II has the same airfoil, but it's a lot lighter/smaller...depends I guess if you want to be able to fly RES.
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Old Oct 19, 2012, 06:01 PM
Making wood fly since 2007
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USA, MN, Rochester
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So what do people think about the wing? Should the ultimate woodie contest sailplane have a fully sheeted wing or would a d-box/open bay design be sufficient? Maybe a combination of fully sheeted inner panels and open bay outer panels?

Wayne
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Old Oct 19, 2012, 06:49 PM
ein flugel schplinterizer
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[QUOTE=Don Stackhouse;23046819]Yes and no. Martin Hepperle has an article on the effects of covering sag. At low Reynolds numbers the turbulating and straightening effects can actually be beneficial.


Yeah, I know that. I was thinking more of the moldie guys cringing over .000001 variation.

Personally I wouldn't tell the difference anyway.


As for a full sheeted wood wing it's certainly workable. I know we're talking about all woodie gliders but if I was going to do that I might just wire out some foam cores and sheet them. However, it would be fun to build a fully sheeted, ribbed wing. Like Wayne (I think) said, wood ribbed and full sheeted center panels and D-box outers.

I worry more about weight on the extremities. When I built my Maurauder I went with CF rod instead of the provided steel for the out board joiners. Also went with lighter covering and replaced some of the kit wood with lighter stuff. Compared to a stock Marauder mine handled amazingly well and danced at the slightest indication of lift. Was just a dream to fly and much more responsive.

Speaking of the Marauder I have got to finish the two I have framed up. Both are pretty much down to final sanding, shaping and covering. Should be interesting to see how they compare to each other. I have a confession to make: When I started on my #2 Marauder, boss handed me another kit and asked me to build him one too. We argued about weight savings (he didn't care) so I dumped both boxes on the table, got out my gram scale and weighed every piece. I made a "Boss" pile and a "Sean" pile. He wanted some things done his way and I went my way on mine. Bet I'll see at least an 8 oz. variance between the two.
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Old Oct 19, 2012, 07:08 PM
Duane
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Quote:
Originally Posted by seanpcola View Post
Yeah, I know that. I was thinking more of the moldie guys cringing over .000001 variation.
Uh... That's about 25 nanometers, the wavelength of extreme ultraviolet light, smaller than some viruses, or the size of some transistor gates. There are very few manufacturing processes with that degree of accuracy.

http://htwins.net/scale2/
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Old Oct 19, 2012, 07:16 PM
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But there are lots of OCD-infected competition sailplane pilots who seem to think it's absolutely necessary!

(that, and getting incidences set within 0.00001 degree of the exactly correct number, whatever that is!)
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Old Oct 19, 2012, 07:26 PM
Duane
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Originally Posted by Don Stackhouse View Post
But there are lots of OCD-infected competition sailplane pilots who seem to think it's absolutely necessary!

(that, and getting incidences set within 0.00001 degree of the exactly correct number, whatever that is!)
Well sure, that's enough to make a difference of 1 inch about 100 miles away. Just think how much that will improve your landing scores.
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Old Oct 19, 2012, 07:30 PM
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The big problem with the "incidence obsession" is that a particular incidence is optimum for a particular airspeed. Even if we think we know what airspeed we want, within that level of precision, in actual practice we fly at more than one airspeed.
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Old Oct 19, 2012, 07:47 PM
ein flugel schplinterizer
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USA, FL, Pensacola
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Originally Posted by Wazmo View Post
Uh... That's about 25 nanometers, the wavelength of extreme ultraviolet light, smaller than some viruses, or the size of some transistor gates. There are very few manufacturing processes with that degree of accuracy.

http://htwins.net/scale2/
Try convincing a bunch of guys at the field, each one holding their new $3500 Thermal Dominatrix 9000, of that.
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