Speedster Tail Ribs

[Doggitz]

I know that parts of my question have appeared in other threads, but they are old and I figure other people might have the same problem, so here goes.

I am building a SS7 with Speedster tail option. After reading through some old posts and very carefully laying out the ribs for the vertical stab, I hysol'ed (is that a word?) them in place. So far so good. I came back to do the ribs on the rudder. My rudder to vertical stab measurements are exactly as called out in the manual (closer at the top, wider at the bottom). When I started to lay out the rudder ribs, I noticed that the distances up the rudder don't quite match with those for the vertical stab ribs. I looked at the excellent build log that Darrel has and followed his advice to use sticks to line up the ribs between the stab and the rudder. I went one step further, I cut longer sticks that basically go from the from the front of the vert stab ribs to the aft portion of the rudder ribs. This is done to be sure that the ribs line up. I got through several of them and noted that I needed to angle the rudder ribs to keep them parallel to the vertical stab ribs. The instructions say to bond some of the ribs to the underlying tubing. The problem that I am having is that the tubing does not line up between the stab and the rudder. Here is a picture of what I wound up having to do to get some of the ribs to line up

The two black arrows show the ribs that don't line up with the tubing. They do, however, line up with the corresponding ribs in the vert stab (after angling them as shown). I even used an inclinometer to be sure that the ribs in the rudder and the stab had the same angle. Has anyone else had this problem? I have not yet glued the rudder ribs in place. I thought I would seek counsel before doing so.


24700


Thanks - Fred
Building SS7
Maybe Rotax 914, Maybe Lycoming O-233

[rwoneill]

Just went through this a couple weeks ago and had a similar issue. None of the ribs fit right out of the box so I had the freedom to put them where I wanted. I figured they would be stronger if they were glued to the tubing. The only downside to this is that the finish tapes may not line up exactly after covering. For me Strength>Looks.

If you don't bond them to the tubing, just add rib stiffeners. The manual says that its optional but it totally isn't unless you varnish immediately. They will bow overnight if you have temp and humidity changes.

I also found it easier to glue on rib stiffeners before they were in the plane. I did the following: 1. Cut ribs to fit 2. Glue on rib stiffeners, 3. Glue ribs in plane.

Two other things I wish I knew before I glued. First, to get nice fillets, dip a gloved finger in denatured alcohol and you can smooth out the hysol however you want. Second, Add masking tape on either side of where the ribs will be glued so you don't have to sand down a bunch of excess hysol later on. Pull the tape before the hysol drys and It will save you finish work later on.

Disclaimer: I'm not an expert builder by any means, but hope this helps!

[efwd]

Sorry Fred, The attachment says "invalid".
From the description I would say, the ribs not attached to steel would be getting the stiffener applied. So, if it isn't attached to the metal, add a stiffener. There is nothing structural about these wood pieces. You can build the plane without the speedster stuff. I believe it is just a convenience in the manual because the existing structure is a "stiffener". IMHO of course.

[jrevens]

To line up the ribs you might have to space a rib or 2 slightly off from a tube, and stiffen it to the tube with a couple of plywood "spacers".

[Doggitz]

Thanks guys. I am in SoCal so I did not rush to varnish because we do not have a lot of humidity changes. I will varnish the vert stab ribs ASAP - just glued them in yesterday.
I looked at a few build videos, including the one by Bryan (Apex Build) and the ribs that the prior builder put in seem to line up pretty well without the problem that I am having. Somewhat frustrating since it all looks so great in the manual.

-Fred

[jrevens]

Hey Fred... I don't know if this is useful to you, but this picture shows basically how I aligned the rudder ribs with the vertical stabilizer ones. I hadn't added any stiffeners to the rudder ribs yet in this picture.

24706

[jiott]

I found that it was much easier if you worked both mating pieces (rudder/vert stab and elevator/hor stab) together right up front when marking out the rib locations so they line up and lay alongside structural members as much as possible before you do any gluing. You can tweak one a little so the mating one lines up better.

[Doggitz]

Thanks for all the responses. I aligned the ribs much as John showed in his response, except that I cut sticks that ran from the from of the VS rib to the back of the rudder rib . I found that using tongue depressor length sticks allowed for too much "play" in the aft portion of the rudder ribs. I wish that I had set both VS and Rudder ribs in place before gluing the VS ribs, but so be it. Thanks for all the responses.

Fred
Building 7SS
Maybe 914, Maybe Continental I-233

[Kitfox Pilot]

Hey Fred... I don't know if this is useful to you, but this picture shows basically how I aligned the rudder ribs with the vertical stabilizer ones. I hadn't added any stiffeners to the rudder ribs yet in this picture.

24706


John, that's broader line to particular...……. LOL. Nice work for sure.