Construction technique

[Jim Jennings]

Is there a “best” method for applying cap strips? Also what is the best adhesive? I am building wings with carbon tube spares, & carbon trailing edge. Any advise?

[MIKE SZURA]

Jim,
This is one way, maybe not the only way.
It is best to place top strips prior to removing from building board. Check that any warps that are to be put in are set-up prior to installing strips
Wipe strips and other surfaces to be bonded clean with alcohol or MEK.
Medium CA works well for bonding, I like thick. A uniform coating is laid on the rib and other carbon surfaces. Place the strip on at the front surface first. Hold there for about 10 seconds or so to insure bond. Then place strip with proper alignment.
Firmly press the strip with a rubbing motion, back and forth. Check to make sure that the strip is holding over the entire area. You may need to weight the area at trailing edge to insure a quality joint. When strips are applied on the bottom, a small plastic clamp works for holding until dry at this joint.
This should give you a start. Let us know how things come out.
Oh yea, what are you building? Building. I like that word.

[Anonymous]

I have just built a wing using a very similar technique, but I used activator on the cap strip and cyano on the rib.This works particularly well with the undercamber.I allow a couple of seconds for the strip to stick at the front end of the rib holding it in place with the tip of a scalpel blade.I twist the blade off and then run the blunt side along the strip till I get to the trailing edge.I then break the strip across the sharp edge of the blade.I find it best if the trailing edge is on the edge of the work table so the cap strip can be pulled down.I line up the strip with my left hand.For the underside I push the strip so that it bends to the undercamber.I did the underside with the wing not held down in any way, and it did not warp.My main problem is getting the polyspan to stick to the undercamber.I covered the bottom first and then applied more dope from above to get it to stick to the capping.Even then, some has pulled away on shrinking.I used spray mount adhesive on another panel rather than dope but that wasn’t much better.

[Jim Jennings]

Thanks guys. It sounds like CA is the adheasive of choice. I have built the WHobby Siga F1A kit using thin CA and stuck as much carbon to my fingers as I did the ribs 😆 . I will try both methods described with thick CA and see which works out. I am currently working on an E-36 electric model. I have built a prototype with hand cut ribs (verbitsky) and balsa trailing edge covered in poly span. It is still 8g heavy, and with a 6″ cord and 36″ wingspan I fear it will be prone to warping. I am hoping that the carbon trailing edge and cap strips will make the wing both lighter and stiffer. Thanks for the advise.

[Anonymous]

I use 1.5mm wide cap strips and trapezoidal t.e. The ribs are 1/16″ balsa,and the structure is rigid.

[Jim Jennings]

The wing is finished. It came in at 32g. I found the 6g I was looking for. What a difference in rigidity! I used thick CA and mini cloths pins for clamps. I cut small pieces of wax paper to shield the clamps. The ribs were strung on the spar on a piece of glass with 123 blocks to insure squarness to the spar. The bottom caps went on next. They were left long and trimmed after the trailing edge was on. The top caps went on last. In the end I did not have any carbon stuck to my fingers and I am very pleased with the results. I appreciate the advise. What a great resource this forum is.

[JLorbiecki]

I also use the thick CA for applying the cap strips. The other trick I use is to make sanding blocks out of popsicle sticks. I apply 120 grit (or other weights) of sandpaper to the sticks. Then, I use these to sand the cap strips to the width of the rib. It is quite easy and, if you happen to miss on the width that you cut the carbon, it trues them up. Works real easy….

Plus, I have found that the popsicle stick sanding “blocks” works well in many other hard to get to areas….

[Dean McGinnes]

Jim,

How did you lose the weight on the wing when you added the CF reinforcing. What was the original construction, and what did you change?

Thanques

[Ed Hardin]

I am new at building with carbon. I noticed the other night when I was cutting cap strips from carbon sheet that my face, especially around my nose and eye started itching, I assume some carbon fibers were released during cutting. Has anyone else had this problem, or am I just more sensitive that others. I have also noticed this when working with fiberglass cloth.
Ed

[MIKE SZURA]

I experienced and still do, the same symptoms. According to my allergist,
the reaction is two fold. Irratation from particles,cutting and sanding
and chemical from contact with the resin and fumes. Reactions can get worse with time. Disposable respirator and either fan or shopvac in reverse to redirect the fumes. This same problem to a lesser extent started with CA a short while ago. Cover up and back to building.

[Anonymous]

I use a vacuum cleaner if I am cutting carbon with a power tool.It is seriously bad for your lungs,although most gets deposited in mucous on the way down and then gets coughed up. Cap strips can be cut with a scalpel blade and bending to make them snap.If I do any filing I do it outdoors.The carbon powder is an irritant rather than allergen.The body has difficulty eliminating carbon as it is inorganic.Thats why miners get pneumoconiosis from carbon dust.

[Anonymous]

A better way than a scalpal, is to just use a scissors. It cuts really nice. No nasty carbon particles.

[Author]

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