I'm getting ready to start a new build that has 1/8" wing ribs. Being rather large and ham fisted, I have a tendency to break ribs during the building process. I have considered reinforcing them with strips of dryer sheets and diluted white glue, but I'm afraid that I might create stress risers in the process. Anyone have any suggestions? Don't really want to cut new 3/32" ribs.

Steve

 These are "regular" ribs. The kit is a RSM Naughty Girl. I'm sure they would be fine if I wasn't a bull in the china shop when it comes to handling the fragile parts.
Steve

Steve, I have to agree with the above replies. But if you do decide to reinforce the ribs, dryer sheets are probably not right for the job. They are covered with antistatic something or other, and some sort of lubricant as a softener which I have always guessed is paraffin. So it may not stick very well. If you really feel the need to strengthen the ribs, the thinned white glue alone, lightly rubbed in with your finger is probably enough. Then you get the added fun of peeling the glue fingerprints off for the rest of the day.
Rusty

This rib Thread got me thinking, so I pull out a wing I built five or so years ago. Halves aren't joined, but the curious thing is, the ribs are all 1/8" thick.

The ribs are from Sig and are the Twister rib. No mistake, says it on some.

I looked at other ribs I have from Sig also, purchased back then, and they are only 1/16" thick, both Twister and Banshee ribs. I have a bunch of them, enough for a wing of each type rib.

Now I'm thinking the 1/8" may be overkill and a bit heavy?

Charles

..... I have a tendency to break ribs during the building process. Anyone have any suggestions? Don't really want to cut new 3/32" ribs.
Steve

Well ........ I am assuming that you are breaking the ribs along the grain so hows about using your original ribs and gluing a cap strip sized vertical grained piece on each rib where you would normally have the trouble. (Again assuming that the breakages are around the rear lead-out area?)

Cheers.

Steve, the difference in strength between 1/16 and 1/8 is pretty big, so that makes a difference.  I would expect to have problems on a rib that's a foot long, perforated like swiss cheese, and made out of good light 1/16.  I'd be much more surprised to break one that's all of the above but is made out of 1/8 unless its super light.

If the problem is something that can be overcome with a light touch and patience, then you may want to work on developing that.

If the problem is something physical -- if you've got neuralgia or some sort of tremors or whatever -- then instead of adding weight to the ribs forever just to get you through the build process, perhaps you should think about ways to make the ribs stronger while you're building the plane.  I'm thinking of some sort of a clamp (if they break when they're going in), or John's vertical strip (which is permanent but hopefully light, particularly if you're sparing with the glue).  I'm not sure what to do if the ribs always break when you put in the spars -- other than to observe that I always clean up my spar slots and mate them to the spars: when I'm thinking about it I do it before they go into the wing, but even if I forget until they're in the plane I do it.

I used CA and balsa scraps to repair the Brodak ribs. They split aft of the LO holes, sometimes between them. I think I'll try the vertical grain pieces where I usually split them . I do have an inherited tremor, much like the one P. Cartier wrote about in his combat column several years ago. Diagnosed 15yrs ago, before I started building planes.
 Its amazing I can shoot .25" groups from my .22Lr @ 50yds. but can't keep from breaking airplane parts. Something about a shooting session  that really calms me, maybe I need to do that before a building session?

One idea is to use a 1/16th X 1/4 piece, vertically between the upper and lower spar cut outs.  This adds a bunch of strength with minimal weight gain.

BIG Bear

I've been installing rib "pillars" to prevent C-Tube wings from crushing when building wings in my Lost-Foam system for more than 20 years. In that system we use weights on top of the top cradle piece to hold the molded shells in place while the glue dries. Tried doing that without the pillars and the result was a very thin (ahem) wing...

The photos attached here show the simple method of stripping 1/16-inch thick balsa that is the same width as the C-Tube spars, applying glue between the spar notches and installing the pillar strip. Simply use the bottom of the notch as a cutting guide and presto, you have a sturdy pillar installed. I make all the pillars face towards the center of the wing. I put them on the right side of the left wing panel's ribs and on the left side of the right wing panel's ribs. Just looks neater that way!

The entire Lost-Foam construction manual is available for the asking. It is broken up into four separate PDF files because of its size. If anyone wants this manual, please send me a request via email at robinhunt(at)rcn(dot)com

I will gladly send out the manual in four separate emails.

Later - Bob Hunt  

Hi Rusty:

I use a variety of sharpened tubes to cut the starter (end) holes. Then I connect the holes using a sharp #11 blade and a metal straightedge. The photos attached here should serve to explain the process. To sharpen the various brass tubes I use a #11 blade and "skive" a bevel onto the inside diameter of the tubes.

Later - Bob

PS: All these photos and lots more are in the Lost-Foam manual I mentioned above. If you want a copy, please email me at robinhunt(at)rcn(dot)com
 

Why not paint with thinned clear dope?  I know it will provide stability to the wood.  Many people paint the structure before covering anyways...

Phil

I have a couple of "hole makers" made out of old golf shafts with the grips still intact.  I sharpen the inside edge like Bob, but sometimes have to use the Dremel, the shafts are stainless steel.  I also add a slot with a cut off disc a couple inches up to knock out the plugs.  The step downs on the shafts allow a couple different sizes.

BIG Bear

Hi Rusty:

I use a variety of sharpened tubes to cut the starter (end) holes. Then I connect the holes using a sharp #11 blade and a metal straightedge. The photos attached here should serve to explain the process. To sharpen the various brass tubes I use a #11 blade and "skive" a bevel onto the inside diameter of the tubes.

   Brass works OK, but it gets dull or the edge bends after a short time. K&S has a series of stainless steel tubes that are also displayed in hobby shops. Sharpen those babies up, and they last forever.

     Brett

 

Now I have never tried this but ....... I have read about using an old chrome and steel telescopic car aerial as a set of balsa punches.

Just slide the interlocked tubes apart and sharpen the lower ends - the steel seems to be quite hard and should hold an edge.

And best of all it should be a zero cost item.

Oh, and Bob I love the light on a stick inside of your wing!

Now I have never tried this but ....... I have read about using an old chrome and steel telescopic car aerial as a set of balsa punches.

Just slide the interlocked tubes apart and sharpen the lower ends - the steel seems to be quite hard and should hold an edge.

And best of all it should be a zero cost item.

Oh, and Bob I love the light on a stick inside of your wing!

I do this with broken RC antennas, (back when everyone had 36mhz radios), but any telescoping antenna is pefect for small radii.

You lose strength.  When you just slap the shear webs onto the side of the spar the glue joint is very weak, and easily lets go in a crash or other high-stress situation.  This is pretty obvious when you look at a wing with such webs that has been thumped.

When you fit them up like Bob does, you almost don't need glue at all (don't anyone jump down my throat -- I said "almost").  The glue keeps the webs located in place, but the actual strength comes from the fact that you've got a rectangle of wood that's neatly filling a rectangular hole.

Note that to date I've been slapping them on the face of my spars, because I had been crashing all the time.  In this situation that's where you want them: when the webs are on the face of the spar, in a crash they break away before the spar suffers serious damage.  This would be dandy, but I've stopped crashing and now for the last year I've been flying a plane built with the philosophy that can be most easily stated as "it doesn't matter: it won't last the year".

Since my next plane may actually last long enough to show its flight time, rather than showing the times it's hit the ground hard, I'll probably do my next shear webs Bob's way.

Greengrocer's apos'trophe's removed, 14.2.4

I have never used the lost foam method, maybe it allows another way to glue the l.e sheeting in place.
But, a handy thing is to at first glue every second shear web in place. Even 1/2 in place gives lots of stability to the wing frame and you still have easy access to glue the ribs into l.e. sheeting. Once it's glued, put the missing half of webs! L

Hi Lauri:

The Lost-Foam Wing Building System provides the ability to perfectly install the molded leading edge shells. And, while it would be possible to glue in every other shear web while building the wing frame, I don't see any advantage to it. I've personally built more than 200 Lost-Foam wings, and while I still occasionally find new and better ways to do things in this system, I'm pretty sure that the sequence and techniques that I've developed are logical and effective as they are. Fitting and gluing in the shear webs after the leading edge shells have been installed allows me to adjust out any minor twists in the wing frames before locking everything up for the duration by gluing the shear webs in at that point.

Note that the leading edge shells are accurately tacked to the leading edge strip on the wing frame while in the cradle fixture and weighted down against a flat bench. The rear of the shell is then trimmed to fit perfectly in alignment with the rear of the spar. Then the assembly is once again weighed down accurately and glued. The top cradle piece from the leading edge mold buck is used to hold the top of the shell in position during the gluing process and this allows access to the front of the ribs to glue them securely to the shells while perfectly aligned. If there is a better way. I'd like to see it...

This is going to sound like an advertisement, and so be it. I've used a great number of wing building systems over the years and none of them yielded consistently perfect wings for me. That's why I developed the Lost-Foam system. Again, I have a free instruction manual available for the Lost Foam Wing Building System. The manual files are large and so must be sent in four separate emails. If anyone out there wants a copy of that manual (from which all the photos I've posted here originate), please just email me at robinhunt(at)rcn(dot)com and I'll forward the PDF files to you right away.

Later - Bob Hunt

Thank you everyone for the info. My upcoming build will be my first "I don't expect to crash" airframe.

Steve

Hi Charles:

I can build any constant chord or any straight taper wing; the design does not matter. Let me know what design wing you are interested in and I'll provide a  quote.

Thanks - Bob

Within reason I can build any size wing; certainly any CL stunt size wing. Yes, I pride myself on making "contest quality" wings, but they can be used for any type of flying. Again, I can quote you a price on a specific wing if you send me the parameters of the design.

Later - Bob

No offense taken, all the pictures and input is what I was looking for. I hope to start the next build(RSM Naughty Girl) in a week or so, maybe post some pics as I go.

Steve

As far as primitive jig I have you beat Tim. I use a melanine covered shelf with 90 deg. brackets attached at the rib stations. I just tape down the bottom spar and then clothespin the ribs to the brackets. Tack glue once I check alignment, then recheck before applying glue. Time consuming but, I know you can force wood  to conform to a jig. If I have anything really far out I make a new part.

Steve

I've been installing rib "pillars" to prevent C-Tube wings from crushing when building wings in my Lost-Foam system for more than 20 years. In that system we use weights on top of the top cradle piece to hold the molded shells in place while the glue dries. Tried doing that without the pillars and the result was a very thin (ahem) wing...

    Another advantage of the pillars on airplanes otherwise lacking shear webs is that it keeps the ribs from splitting chordwise from shear in the spars. I recently had the, uh,  opportunity to see the inside of the Skyray wing (balsa version). It is a C-tube with 1/8x1/2 10 lb spars set vertically at the high point, which means about 3/4" of unsupported balsa between the top and bottom spar slots. The spars themselves are pretty stout, but the airplane has always been prone to pulling an alarming amount of dihedral. easily visible to casual observers.

    When it was disassembled, the wing that hit the ground had every single rib (3/32 4.8 lb) split from the front clearance to the rear clearance. I then stripped the other wing which had been undamaged - same thing. I am pretty well convinced that the ribs all split there on the first hard corner. Bobby's pillar would have kept it together.

    The obvious question is, why no shear ribs? Thats because I wanted to be sure that the wing was flexible enough to take multiple crashes. That it did, easily 30-40 of them, with only cosmetic damage. Shear webs would have kept the dihedral out of it, but they also would likely have caused massive damage on a crash. At the least, I would expect the spars to have broken in a pancake landing, probably at the root. As it was, when the covering shattered, the spar broke right at the end of the center section sheeting - which made it to rigid.

   The stock wing was light ply and spruce straight out of the kit, and it was much stiffer (and absurdly heavier) It shattered in to MANY pieces on the first significant crash and was utterly irreparable. I threw the balsa wing together in about and hour and a half, and it lasted close to 20 years and multiple crashes. Maybe surprisingly, the original airplane was something like 5-6 ounces heavier than the rebuilt model, but with the 20FP it made nearly NO difference in the performance. Right to the end, it was limited by the tail moment and elevator movement, not the wing loading. But the lighter wing was far more durable.

    It may have survived this crash, too, if the Monokote had remained flexible like it was when new. As expected, in the pancake crash, it shattered like glass after sitting out in the sun on and off for 20 ish years. I wadded it up and it cracked into a million pieces. The covering on the bottom was a little stiff, but didn't crack and could not have a finger punched through it easily like the top.

     Brett

Perhaps a little tent over the plane... we could call them Brett Buck's quonset huts.