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Old Feb 20, 2011, 12:51 AM
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ieyasu's Avatar
USA, CO, Fort Collins
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Build Log
Chrysalis 2m Build

I have begun my Chrysalis 2m build, starting with the wing. First, I taped the instructions, a full-size sheet, to the wall for easy access. The next step was to label each rib as per the diagram. Easy enough.

Next, I weighed the spar stock and sheeting, distributing weights to balance the panels and putting heavier stuff inboard and on the top. This should maximize strength and limit the need to balance things later.

Then I laid out the trailing edges, spars, and cut balsa sheeting for the dihedral and poly breaks. The ribs help align the spars and the shear webs help to align the ribs. So far only minimal cutting and sanding. Yay kits!

I have chosen to use Titebond for most joints, even when CA is called for. I find I make a clumsy mess with CA, and I never can get the thin stuff to stick. Not sure what I'm doing wrong, but wood glue makes me happier anyway. Where epoxy is called for, I will still use epoxy of course.
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Old Feb 20, 2011, 09:03 AM
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United States, OK, Moore
Joined Jan 2006
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Looking good! I've heard all the high praise about the Chrysalis kits, but being able to see the instruction sheet, plans, and parts makes me a believer. Looking forward to more construction photos.
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Old Feb 20, 2011, 09:08 AM
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One thing to watch out for when using Titebond or other water-based glue: when you're gluing flat surfaces together, particularly the upper spar cap to its doubler on the inboard wing panel, the water in the glue can make the wood curl away from the joint, making the upper cap and doubler want to split apart from each other at the edges of the joint.

Possible fixes:

Brute force - clamp the daylights out of it. Not really very effective or reliable.

Use epoxy instead of Titebond in those cases. A bit heavier, but good strength and it works.

Wet the outside faces of the wood on both sides of the joint, so the wood pieces are wet on both sides. This cancels out the tendency to curl.

Just use C/A for those joints.

This problem can also be an issue when gluing the balsa fuselage sides to the ply doublers. In that case you're dealing with balsa, which is a little easier to "brute force", but the place you will need to watch is along the botttom edge. The curling effect can make that try to spread the joint open, where it's difficult to detect and difficult to clamp.
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Old Feb 20, 2011, 09:25 AM
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United States, TX, Blackwell
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Quote:
Originally Posted by Don Stackhouse View Post
One thing to watch out for when using Titebond or other water-based glue: when you're gluing flat surfaces together, particularly the upper spar cap to its doubler on the inboard wing panel, the water in the glue can make the wood curl away from the joint, making the upper cap and doubler want to split apart from each other at the edges of the joint.

Possible fixes:

Brute force - clamp the daylights out of it. Not really very effective or reliable.

Use epoxy instead of Titebond in those cases. A bit heavier, but good strength and it works.

Wet the outside faces of the wood on both sides of the joint, so the wood pieces are wet on both sides. This cancels out the tendency to curl.

Just use C/A for those joints.

This problem can also be an issue when gluing the balsa fuselage sides to the ply doublers. In that case you're dealing with balsa, which is a little easier to "brute force", but the place you will need to watch is along the botttom edge. The curling effect can make that try to spread the joint open, where it's difficult to detect and difficult to clamp.
Don, I appreciate these insights as I ordered one of your Chrysalis kits a couple of weeks ago and I'm eagerly awaiting it's arrival.

ieyasu, Looking good! I'll be following your progress closely. Thanks for posting your build!

Jim
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Old Feb 20, 2011, 11:07 AM
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Keep the pictures comming

ieyasu,

Thanks for doing the build log. Keep the information and pictures comming.
I will start building on mine sometime next week,so I'll be watching your every move I first have to complete my DLG conversion to electric.

This will be my first build since I was a kid,other than some Arf's, so I may be asking some questions if you don't mind.

Don,thanks for all your help and input. I'll probably be asking you some questions also.

Looking forward to following your build,and building mine.

Eddie
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Old Feb 21, 2011, 05:03 AM
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I don't have one of these but I always enjoy following a build thread.
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Old Feb 21, 2011, 07:23 AM
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Originally Posted by aeajr View Post
I don't have one of these...
You know, there is a way to fix that. ;-)
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Old Feb 21, 2011, 08:55 AM
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Wow, so many comments! Thanks for the interest. I'm sure this will help me finish the plane faster than I otherwise would.

I've made a bunch more progress since my first post. Also my first blunder. Like Adam Savage on Myth Busters, I sometimes charge ahead without thinking about what I'm doing. I got to the step where you glue in the tip sheet and gusset and decided that it should be mounted flush with the board and started cutting to fit between the spars. WRONG! After thinking a bit and slicing through half-dried aliphatic, I discovered that it was obviously correct to place these bits on top of the spars, centered on the ribs so they are level with the leading edge; they do not need cutting at all. Fortunately I had some scrap balsa to splice the tip back together.

I've got more photos to come, but I will post them later.

Don: I just double-checked the instructions, and they indicate the use of "white glue" for the spar doublers. At any rate, I used Titebond on them already, and after holding them together by hand until they stayed in alignment, I placed them on my wood floor with several pounds of lead on top while the glue dried. Maybe it was dumb luck, but they came out fine.

I'll take extra care when I get to the fuselage. I've laminated balsa on Gentle Ladies both ways. The thinly spread CA cured instantly and freaked me out, but I can get things aligned the first time sometimes, so it all worked out
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Old Feb 21, 2011, 02:19 PM
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This whole issue is a bit of a "grey area".

Titebond counts as a "white glue". In terms of the finished strength of the joint, the general consensus seems to be that these glues give the best and most consistent joints in wood-to-wood joints, although the differences for most of the other options are relatively small.

One of the woodworking magazines did a pretty extensive test recently and found that glues like Titebond were best for overall joint strength in most cases, most of the other options for joining hardwoods (epoxies, old-style hide glue, etc.) were close, with some variations due to species, fit of the joint, etc., but about the only one that was substantially weaker on hardwood was urethane adhesives (Gorilla Glue, etc.). Those foam up when they cure, and besides tending to push joints apart if not adequately clamped, the foamed nature of the cured adhesive does reduce its strength. For joining materials with limited strength, such when gluing foam or balsa, that isn't a problem, but for stronger materials it could be.

Back when I wrote those portions of the instructions for the HLG and 2-meter, it seemed like the best choice, but today I have mixed feelings. Fortunately, the spar caps are narrow enough that the curling effect is minimal, so it normally isn't a problem. However, since I began repairing fiddles and other stringed instruments I've become a lot more knowledgeable about, and sensitive to some of the nuances of fine woodworking, and the curling in response to moisture in particular.

What you do need for that joint is something thin enough that it doesn't interfere with getting the joint assembled, but not so thin that it wicks away into the wood, and above all else it must be slow enough to give you time to get everything together before it starts to set up. For this reason slow C/A might work OK, medium C/A might be a little trickier, thin (fast) C/A would definitely not be a good choice. Epoxy might work, provided that it was not so thick that it interfered with getting the parts together (some 5-minute epoxies could have some problems).

The "aspect ratio" of the parts involved is definitely a factor. In the case of the spar caps for the 2-meter, the width is only about four times the thickness, so the curling is less of an issue. One of the projects I'm working on now uses much wider spar caps (but still about the same thickness), and on that aircraft the curling effects of moisture in the upper spar cap doubler region are definitely a potential problem. The species of wood involved is also an important factor, some types are much more sensitive to this than others, and the ease or difficulty of dealing with it also varies. The first one on the prototype that I tried using Titebond had serious curling problems. Actually, the easiest option on that one turned out to be medium C/A. 15-minute epoxy would also work, but the instructions will definitely advise against white glue on that joint.
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Old Feb 21, 2011, 08:49 PM
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More Progress

As promised, more pictures. I put in the rest of the ribs, top spars, and shear webs. There was a little more sanding to fit, but it went quite smoothly all the same. I 'cheated' and did half of the next step in the last photo by installing the leading edge already.

The L.E. would have benefited from CA, but I stubbornly stuck with my aliphatic ways. To help deal with the sharp curvature on the outer panel, I used steam from an electric teakettle to bend the dowel into roughly the right shape. I haven't bent much wood before, but that was a blast! It makes it harder to get glue into the joint since the dowel has to be actively bent back straight again, but I like the idea of less tension in that bit of wood.
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Old Feb 21, 2011, 09:02 PM
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[QUOTE=ieyasu;17477846]As promised, more pictures. I put in the rest of the ribs, top spars, and shear webs. There was a little more sanding to fit, but it went quite smoothly all the same. I 'cheated' and did half of the next step in the last photo by installing the leading edge already.

Looking good.

I hope to get to mine by this comming weekend. Retirement seems to keep me busier than when I was working.

Good pictures, keep them comming.

Eddie
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Old Feb 21, 2011, 09:53 PM
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I'm following this thread with much interest. I've long admired the looks of the Chrysalis- it reminds me of the classic "Great Speckled Bird" FF designs from George Perryman. Any influence from there Don?

I may just have to order a kit and add it to my collection of models I don't have time to build.

Cheers,
Dave
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Old Feb 21, 2011, 10:59 PM
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... I've long admired the looks of the Chrysalis- it reminds me of the classic "Great Speckled Bird" FF designs from George Perryman. Any influence from there Don?...
No, I vaguely remember hearing the name, but I'm not familiar with those. I recall the country and western song with that title, mainly because I intensely disliked it.

Growing up, I liked the designs of Carl Lorber, among others.

I like conic sections (the curves you get when you slice through a cone, such as circles, ellipses, parabolas and hyperbolas). Their perfect mathematical smoothness (natural for a second-order curve, unlike third order cuves such as the NURBS and other splines most CAD systems use) is naturally pleasing to the eye and to the airflow. A conic is mathematically incapable of any wiggles, even on a microscopic, subliminal level. In general, almost any curved shape you see in the Chrysalis, other than the airfoils themselves, is some form of conic section. Even in the airfoils, there are three baseline airfoils along the span, but the non-linear blending in the portions in between also uses conics for smooth transitions of things like camber and thickness.

The technology in the wings goes all the way back to extensive experiments on low Reynolds number airfoils that I began in the late '60's, along with various influences from other sources that I picked up along the way.

Much of the overall design is the natural result of choosing what would fly best. No, I'm not saying that something that looks good will fly well. I don't really subscribe to that old adage. I generall believe the inverse - that something designed to fly well will tend to look good.
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Old Feb 22, 2011, 09:12 PM
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Not familiar with the song, but here's a picture of the model. There's a definite resemblance I think.
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Old Feb 22, 2011, 09:27 PM
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Michigan, USA
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And here's the song...

Roy Acuff The Great Speckled Bird (2 min 44 sec)


Enjoy!
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