Millenium Wing....

Anyone else building these?

Well, of course I have a problem. I followed the directions for the thing. I glue in the upper rib strips to the spar. When I flip it over the rib strips won't rest on the shelf of the leading/trailing edge. I've examined what I am doing several times. I dry build, as far as laying the rib strips over the plans and it is still wrong. It is a Cardinal wing I am trying to do this on.

I built a Chipmunk with a lincoln log and it came out fine.

So I'm scratching my head on this one. Any ideas?

rib slices, doesn't that make you hungry? Does me....

LAST EDITED ON Feb-06-04 AT 07:26 PM (CDT)
 
I'm not sure I understand the problem. Are you saying that you put in the rib strips on one side of the wing, flip it over and it doesn't fit in the jig? Or is something interfering with the wing laying back in the jig?

Generally, if you build the wing in one piece instead of separate inboard and outboard panels, those panels must be of equal length. If the wing is asymetrical, you need to make provisions for when you turn it over since it won't fit the other way. If you build separate panels, remember that you can't just flip it over in the same jig. You have to move it to the ajoining jig since the taper will now be ther wrong way.

Hmm, I don't know how clear that is. Unless the inboard and outboard panels are the same, building the wing in one piece in a millenium wing jig may be problematic.

Randy Powell

Edit: for clarification---

>>When I flip it over the rib strips won't rest on the shelf of the leading/trailing edge.<<

So, are the rib interfering with the LE/TE resting in the jig? or does the wing now not fit in the jig?

I'm guessing that he means that the strip ribs on the second side did not extend far enough toward the 1/16" sandwiched "ledge" of the l.e. and/or t.e. to make contact - or that they extended too far and thus arched up over the spar. Probably the former. I was worried about that possibility on mine, and since all my ribs were particular sections generated in a tapered array, I decided to build them up before inserting them into the spar slots. I was very careful in cutting everything, and they fit pretty closely. You can move "New Millenium" jig blocks to match taper when flipping an asymmetrical wing.

I can see how the rib slices might miss though. Perhaps they even changed camber from release of internal stresses when they were cut. If my interpretation of the problem is correct and IF resulting asymmetry is not too great, one or a combination of the following might be done, depending on the particular type of problem:

1) The slots can be deepened, and some of the spar sanded down to rib height.

2) The "ledge" could be augmented with a lamination, or the ribs shimmed up, effectively increasing section thickness without asymmetry.

3) New slices can be cut with more vertical thickness at the ends (if already too high, of course you'd just cut them down).

4) The spar can be built up between ribs, if extra height is to be retained.

In other words, if the fit isn't too far off, the fix is not too difficult. Otherwise, it sounds as though the rib slices and spar dimensions will have to be refigured and cut.

Perhaps there are other options? If I've interpreted wrong, then, "Never mind".

SK

Serge,

I must build mine different. I put in the LE and TE into the jig. I then glue the rib strips in and flip the wing in the jig to put in the ribs on the other side. I build symetrical wings, so it works OK. I then insert or build up the spar or spars. The new elliptical plane has 2 spars, one at the high point and one along the front side of the TE sheeting. But they are built up after the ribs are in. It was the only way I could get the taper to stay consistent and the wing to stay straight throughout the building process.

So, I didn't experience what your describe. No wonder I didn't get it.

Thinking further on the problem, I remembered that this is a "Cardinal" wing. That must mean that the spar plans were hand drawn, since the cardinal wasn't designed as a "New Millenium" wing. Otherwise, I would not expect initially identical rib strips (but chopped to different lengths) to fit the taper of a wing design with a succession of family ribs having similar shapes. Perhaps the spar taper isn't correct? It would have to be designed using rib strips cut to appropriate length for root and tip, layed out to determine the vertical separation between the 1/4" thick slices. That SHOULD insure that appropriate contact is made when the wing is assembled. Otherwise, built up ribs from individual slices fitting the original design contours can be used to give the original thickness taper. Either way, the spar taper must correlate to the rib heights.

SK

Yes, Serge you were correct. The whole mess is still sitting on my work bench. I encountered many problems.

When I had cut the rib length off the plans they wouldn't touch between the leading and trailing edges. For that I redrew the ribs by hand, with a smoother taper.

For the spar:

I measured the wing panel, cut a piece of 1/8 X 3 balsa to length. Marked a center line. On the plans measured the height of ribs #1 and #14. Transposed those measurements to the balsa. Then cut in that taper. Measured out the rib locations and cut down 1/4 inch.

That internal stress thing makes sense...I'm going to see what I can do with the mess on my bench...

It definately didn't just go together like in the instructions or like one of you had previously written...

LAST EDITED ON Feb-07-04 AT 09:23 PM (CDT)
 
>On the plans measured the height of ribs #1 and #14. Transposed those measurements to
> the balsa. Then cut in that taper.

Just had to make sure: Did you measure the rib heights at the chordwise station where the spar passes and did you bevel the spar to mate with the rib contour? If so, it appears that warpage is the culprit. When I made my strips, I cut out balsa rectangles slightly bigger than respective ribs before drawing the ribs (actually rubber cementing a photocopy) on the balsa. This wasted only a little balsa, but minimized internal stresses. I honestly don't know how much this helped though, and it somewhat defeats the purpose of the mass-production rib-slice technique.

SK

Edit: P.S. I just read Dale's response below and agree with his concerns. I have spent some time looking for airfoils that lend themselves to this technique and find that they seldom approach the ideal for wings I've drawn. The wing design certainly determines optimum rib slice shapes, even to the point where few if any may work well for certain planforms and thickness tapers. I assumed initially that a "New Millenium" wing for a "Cardinal" would differ in sections from the original, since high point positions would often be a problem for planes originally designed with standard tapered C- and D-tube wings. I will be interested in responses to his questions.

LAST EDITED ON Feb-06-04 AT 07:40 PM (CDT)
 
I was also a bit confused by your question.
When I built mine, I glued 3 or 4 rib strips onto the
top side of the spar, as a straight as I could, then set the spar and
ribs into the jig, with the 3 stribs supporting the spar between
the LE and TE shelves. Then I added all the remaining strips
to the top, gluing them at the spar and both shelves.
That was fun; took about a minute.

After the glue dried, I flipped the whole thing over and
placed and glued rib strips for the other side.

Then sheeting, rib caps, etc.

The 3 initial strips were the only step that seemed worrisome.

LAST EDITED ON Feb-07-04 AT 00:41 AM (CDT)
 
I think Serge may be right with the rib strips relaxing their camber. His fixes seem correct too. I built 2 Mille wings, 1 for my Jamison Special, and the other for the Actroma 40. I have pictures of both wings when I was building them posted on my website. Good luck and let us know what you did to fix it.

Did you cut the rib strips yourself,or did they come as part of a piece kit?In the last 2 years I've built around 30 or 40 millenium wings of various designs and some have to be done differently.The Cardinal has a severe taper in thickness from root to tip,so to get it accurate you either have to cut all #1 ribs and size them as you go by taking some off the front and back as you go toward the tip,or build it Lincoln Log style.Wings such as Orientals,with a constsnt cord and constant airfoil from root to tip are the easiest.Randy Smith's SV wings work well also because his have very little thickness change from root to tip.Cardinal's,Trivial Pursuits&Patternmaster's all have the fat root and thin tip,so they have to have the ribs custom cut as you go to work out.
If you cut the slots deeper you end up with a different airfoil top and bottom.What I've done with some wings is get one side of the wing(top or bottom)done with all ribs in place,glued to the TE&LE,but not the spar,flip the wing over and do the other side.Sometimes the spar will find a mid-point and your airfoil will be accurate.
If the ribs are not far off the ledge,weights can be put front and back to hold them in place til they dry.A little forcing is OK,just check the airfoil.
Dale Barry

okay...That's what I experienced and was wondering about the building method.

As I said I have done a Lincoln Log wing, for a Chipmunk and actually for a Cardinal too. I saw alot of benefits to the millenuim wing and wanted to do one of those.

Dale just as you wrote. I started with the #1 rib and sliced as needed but by the time I get to rib #14, it is a different airfoil shape.

I know Tom Morris pretty much specializes in Caviliers and didn't know if that was a plane that worked perfectly for a Millenium wing.

Ever feel too, when you read any article. You can't find the same products / materials people use? Drives me crazy!!!!

Thanks for everyones input.