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-   -   RV-3B Dave's in Colorado (http://www.vansairforce.com/community/showthread.php?t=85658)

David Paule 07-14-2012 07:56 PM

Some Horizontal Stabilizer Progress
 
The frame of the horizontal stabilizer is finally done. No major surprises, and a lot of education. The skin is next and although they are are out of the box and in the shop, I didn't manage to get them in the picture.



In fact, I'm not sure they'll even fit in the jig without trimming. Part of the job.

By the way, the tooling that you can see in the forward inboard ribs, sticking out where it will interfere with the leading edge of the skin, has been trimmed to clear. No worries there.

It's worth mentioning that although the ribs and channels come pre-bent, nothing in the stabilizer comes pre-drilled. The hinges, for example, come as a piece of aluminum angle, undrilled, uncut and unmarked. It's an RV-3B.

Dave

mtnflyer 07-15-2012 06:20 AM

Dave,,, good luck on this build. When you line up at the end of the runway, feed in the throttle, and lift off, it will be the biggest thrill of your life, and the pride of saying, " I built it" is beyond belief. I,m just over the hill in Granby, so if you have any questions, shoot me a PM....Dave

David Paule 07-25-2012 04:29 PM

Fear
 
Now that the skins are all drilled to the horizontal stabilizer, I went and rechecked their alignment. Yeah, I know... I should have either done that earlier or not at all, right? Anyway, what I found was that nothing seemed anywhere close to true. It was so bad that I resolved to take care of it now before dimpling the frame and the skin. First, I added up the parts prices from Van's in case I had to toss it all out and start anew. It was more than $400, which got my attention.

First thing was the hinge alignment. That's was the only place that I knew was good so I started with that. The hinge stand-offs were accurate to their line on the base of the jig. Then I went to the taut wire at the top of the jig (and don't you just love it when someone lets their spell-checker accept the word "taught" for the word taut? - My taut wire seems resistant to education, sad to say) and hang a plumb bob down to the line. Some adjustment was required. I tweaked this and that until the plumb bob was, well, plumb.

Next up, I relocated the 1/4-20 threaded rods that hold the end ribs. The final bit of realignment was to adjust the holder for the threaded rod which keeps the inboard forward ribs in the correct pitch position and the right position inboard/outboard. Tweaking the ribs to the right position in/out was the hardest part here.

Two things left to do. The first was easy - I went and got a fast-drying goop similar to Bondo and put a blob on each of the feet of the jig, anchoring it to the floor, so I won't move it by leaning against it like I did last time. Oops, didn't mean to mention that.

Finally came the fear part of all this. Would the skins line up again? Would I need oops rivets all over? Or would I need new skins? And if I did need new skins, what about drilling them to the frame?

I hung the skins on the frame, and to my considerable surprise, they lined up. No wrinkles, no agony, they just fit. Clecos went in anywhere I wanted them to. And when I rechecked the alignment with the skins on, they appeared true.

Got lucky there.

Dave

David Paule 08-09-2012 12:05 PM

Scrap!
 
I screwed up riveting the skin to the substructure of my horizontal stabilizer. You can see the way it turned out here:



There were two issues. The dimpling on the front spar used a dead-beat hammer and not my trusty two pound ball peen hammer (which makes excellent dimples) and the poor riveting with the gun.

I went down to the airport and looked at a couple of handy RV-4s. After that it was clear that I need to scrap this stabilizer.

A new stabilizer is on order. There were some other issues with this and I expect that the replacement will be acceptable.

The tip, also shown in the picture, is as it came from Van's. It's not attached nor trimmed. See how its contour is different than the surface? Since the tip skin contour is fine (the tip rib matches the layout in the plans and the skin matches the tip rib) the error is in the tip. FYI.

I marked my skins by which side of the shop they belonged to, when on the substructure in the jig. We're looking at the north side of the jig, and the east side of the stabilizer (NE). It was easier to deal with that than trying to remember which was right or left or top or bottom. The RV-3B horizontal stabilizer is almost symmetric. Except for the orientation of the splice plate, it is symmetric.

Dave

rph142 08-09-2012 03:42 PM

Hang in there!
 
I'm having flashbacks to when I decided to toss my first HS. The second one should be much nicer in half the time so dont sweat it. You'll be glad to have this spare to practice on when it comes time to paint.

David Paule 08-09-2012 04:12 PM

Thanks! -- I sure appreciate the kindness.

Hadn't thought about the painting benefits. Great! I always like to have a crash test dummy on hand before trying something new.

Dave

Ironflight 08-09-2012 06:41 PM

We got lucky on our tail Dave - it was a "quick build"! (The first owner of our kit had built four RV's previously, so his quality was excellent).

On the tips, I hate to tell you this, but they don't get much better than that. You're going to become expert at fiberglassing.....

Paul

David Paule 08-10-2012 11:26 AM

Periodically, I get tempted to buy a partially-completed kit. There's on in the Classifieds today, as a matter of fact, that would save me two to three years. But I'd like the privilege of building it myself. For me, the building is - at least right now - slightly more important than flying it, since I've got an excellent airplane already.

That's too bad about the quality of the fiberglass parts. I was hoping for better. Good thing I've got composite experience. It came from owning, sailing and tweaking a Corsair F-27 trimaran sailboat. That thing was the best handling vehicle I've ever operated.

Dave

David Paule 08-22-2012 05:26 PM

New Horizontal Stabilizer Spar
 
The new spar for the horizontal stabilizer is complete. Van's had shipped the replacement parts quickly but I had a series of non-RV-related things occupying my time so it's been slow. The new hinges are on. I'm reusing the center hinge and it's lined up and drilled but not yet bolted on.

I took the scrapped stabilizer to an EAA tech counselor who acknowledged that it was rough but didn't seem too dismayed by it. We talked about ways to do better next time.

The ribs are on my work table right this minute but so far I haven't worked on them.

Dave

David Paule 09-21-2012 09:18 PM

2nd Horizontal Stabilizer Coming Along
 
At this point it's mostly just waiting for a friend to drop by to finish riveting. We have one side of the front spar riveted but only part of the other.



The tip of the skin is being held up for clearance so that my friend can get in and buck the front spar rivets.

While waiting, I deburred the main ribs for the wings and straightened their flanges. An RV-3B only has 24 of these and that went quickly.

Then I started building the rear spar of the vertical stabilizer. I got farther than the photo shows. The hinges are located and drilled too.



And I brought home most of the elevators and rudder, except for the skins.

Dave


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