Bonding ribs, horizontal stab

[Flyboy66]

When bonding horizontal stabilizer ribs into place, do I bond the sections where the welded structure passes through the ribs? How do I know if I need stiffeners? The ribs are all strait, but will they bend with an air load, or when the fabric is shrunk?

[jrevens]

Hi Steve,

FWIW, I installed stiffeners on most all of the ribs that weren't in contact with one of the steel "ribs"... that includes the elevator ribs. I also bonded to the structure that passes through them.
Here's a representative picture -

[Esser]

I did my rudder with no stiffeners only to find out the humidity caused them to swell and warp. In my opinion, stiffeners are not optional unless you are bonding it to something along side it.

[Flyboy66]

Half (just under) of the horizontal stab done. I need to go glue the ribs with weldments through them. Was waiting to hear/see back from you guys. Dinner, then trimming the ribs for the other side.

After gluing, I went upstairs to show neighbor wings and fuselage, and noticed that KF uses a lot of adhesive to bond the wing ribs in. Did I use enough adhesive to bond in my ribs?

Tomorrow, I will install stiffeners on today’s work and install ribs in the other half.

[jiott]

By all means, use stiffeners on all ribs not otherwise stiffened by a steel structural member. The kit typically does not include enough stiffener material so you will be tempted to skip it on some ribs, but go buy some 1/8" ply from the local hobby shop and cut some more. I skipped some on my elevator and was sorry I did. The fabric shrink process pulled the outer steel tubing in just enough so that some of my unstiffened ribs took on an "S" curve. Not a show stopper, but not good in my book.

[Flyboy66]

I am sold on stiffeners, but it raises another question. How do you clamp the stiffener in place while the adhesive sets?

Any pictures?

The outboard 8 ribs are now installed on the stab. Tomorrow is stiffener day as well as elevator rib day. Also, what about foam versus balsa wood for the outer edge of the stabilizer?

[aviator79]

By all means, use stiffeners on all ribs not otherwise stiffened by a steel structural member. The kit typically does not include enough stiffener material so you will be tempted to skip it on some ribs, but go buy some 1/8" ply from the local hobby shop and cut some more. I skipped some on my elevator and was sorry I did. The fabric shrink process pulled the outer steel tubing in just enough so that some of my unstiffened ribs took on an "S" curve. Not a show stopper, but not good in my book.

I stiffened all of the HS ribs, but since I didn't have enough material, I did not do the elevator ribs, as they were all nice and straight. Tightening the fabric was enough compression on the steel structure that most of them bowed a little. Fortunately, the elevator ribs follow a linear contour from LE to TE, and you actually can't tell in the finished product, but I wish I would have stiffened them.

Get the ratcheting gun with dubble barel syringes with mixing tips if your looking for great filets. If I remember from my visit in April, Brandon has an air driven applicator gun with mixing tips.

You can get this adhesive and a much cheaper non-branded gun from McMaster Carr. I just used mine for the first time, and now that I've seen the light, I would have used this from the beginning despite the cost. You'll need to order a half ton of applicator tips, but you will waste very little adhesive. My glue work does not look as good as John's, but it would have if I'd used this gun from the beginning. Also really nice not to have to mix. Just put the tip on and go!