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Horizontal Stabilizer Riveting

May 8, 2011

I always seem to underestimate how much time stuff is going to take.  I figured I’d be able to show you a finished HS today and I could move on.  BAH!  Not going to happen.  So I started assembly and riveting of the HS this weekend.  I wasted a lot of time on HS-707 which I’ll write about in a minute.  But here is a shot of todays work.

Rivet line on HS702

So this is the left hand, bottom of the horizontal stabilizer.  I got all the rivets in the field and I still have the rivets along the edge.  For those of you playing at home, thats HS702,707,708 on the bottom are complete.  I still have 704,705,706 and the rear spar to rivet, and most of the rivets on the top.

One of the things that took time today was this is the first piece that you have to do a considerable amount of bucking.  Many of the rivets simply cannot be squeezed.  Michelle got her first taste of bucking since our SportAir class.  We goofed a few, but nothing bad.

Now, if you’re building and you happen by this page hoping to find wisdom about getting HS707 mounted then please take heed.  HS707 is a nose rib.  The forward spar runs through the middle of the HS structure.  The nose ribs are riveted to the forward side of the spar and help give the HS a nice aerodynamic shape.  Being in the very front means that sometimes these nose ribs cause fits getting the rib installed.  Vans directions do work, but you have to modify them.  In Vans directions they tell you to cleco and then rivet HS707 onto the top skin, then flip the piece over and rivet the bottom side.  Kind of like this:

If your kit is anything like mine…this is just a pipe dream.  The amount of “spring back” in the skin is so great that it can litterally rip the rivets out of the holes.   Don’t ask me how I know.  If you look at the full size of the picture above, see how wide apart the skin is?  There is a tremendous amount of force as it trys to rip apart the 14 AN426AD3-3.5 rivets that are holding it together.  Those 14 rivets are the only thing holding it together, at this point.  My clecos ripped out as we tried many ways of getting the blasted things together.  Here is what we did to get it working.

Go ahead and cleco and rivet HS707 to the top of the skin as instructed.  Then cleco all the other parts together, 702, 704, 705, 706, 708 etc.  Cleco all those pieces to the skin on the top, just like the HS707, and cleco 707, 702 and 708 together.  Put a cleco in every hole.  Then flip it over and cleco everything on that side, paying attention to the amount of force you are placing on 707.  Make 707 the last thing you cleco…even now its going to be under a lot of force and the clecos may want to come out.  Drill out the two rivets holding HS704 to the 702 spar.  You’ll need to get your hand in there to buck the rivets on the bottom side of 707.  Once you’ve bucked the 707 spar, you can put rivets back in the 704 to 702 holes and continue following the instructions.   If you simply cannot get clecos to stay in the holes, just punt and go with the blind rivets.  They’ll be underneath the HS, so nobody buy you will know they are there.

As usual, now that I know how to do it, the other side shouldn’t take nearly as long…but I still have a lot of rivets to go on the left side.  Maybe tomorrow night I’ll get the left side complete and can report success.

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