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Not enjoying this part very much - elevator

brewtoo

Member
I have mucho respect for all who have built an RV and even more respect for those who have built an RV and managed to maintain great, informative web sites, too. What a fine community!

I am almost done with my RV-7 Empennage. About 1.2 elevators is all that is left. It's been fun and progress has come more quickly and easily than expected.

The HS, VS, and rudder were all fairly straight-forward to build. I guess the toughest part was the little Ribik's Cube section where everything comes together in the center of the HS. But I made it thru that OK and have needed to order no replacement parts.

I must say, though, EVERYTHING that has to do with the elevator counterweights has been a royal pain. The ribs, the counterweight skin, the counterweights themselves. The first problem was that the PP holes in the ribs would not line up with the holes in the counterweight skin. Some were literally almost one hole width off - too wide. I foolishly thought it might be better after I riveted the ribs together, but no, it was worse. I called Van's twice. The first guy said just drill the holes out to an oval shape and it would be fine. I didn't like that idea. The next guy said use the Brute-Force method. I didn't like that idea, either. Thay said this was a common problem. I wish the smaller rib had simply not been pre-punched, then I could put the holes where they should be. And while many people have problems riveting these ribs to the end of the spar, curiously I had no problem at all with that. Trimming/drilling those lead weights? I never realized that working with lead would be like working with glue.

Everything I have worked on besides this elevator counterweight area has turned out great...truly work that I can be proud of. Conversely, I do not feel good about this elevator counterweight area. I have not been able to achieve the fit and finish here that I am comfortable with.

Thanks for listening,
Michael
 
After going through two sets of ribs, I also suggested to them that they simply stop prepunching that rib. That was the only part on the whole empennage where the fit was just really awful.
 
Elevator Woes

Hi Michael,

I certainly understand your frustration. That was a difficult part for me. Took a couple of tries to get it right. One problem I ran into was a mis-bent elevator skin. Simply could not get things to align. Van's eventually sent me a new skin and stiffeners. The issue is that the computer puncher is perfectly accurate. The brake that bends the skin is dependent on the operator getting the skin in just right. If they are a 1/16th off, then the holes don't align with the ribs. Another potential fix Van's offered was a set of unpunched ribs. I decided to go with the new skin and started over.

The other really difficult part is getting the bent in the skin that faces the trim. Many people abandon that bend and make a small rib to fit in there. It also took me three tries to bend the trim skin correctly. I am slow but also a severe obsessive compulsive about getting it right.

Working with the lead was really not that difficult for me. I used a vixen file and didn't have much trouble shaping the lead. Perhaps you might try that?

Anyway, keep working. The wings are considerably easier, in most respects.

Regards,

Michael Wynn
RV 8 Wings (almost closed)
 
Today I saw a couple of finished RV-7s. They both had simple rectangular lead blocks for elevator counterweights, mounted inside the rib.

Mine has a big molded lead piece that you install right out on the end of the counterweight ribs. It actually closes the end of the fiberglass tip. Which is the newer design? My kit is from 2001.

Looks like the rectangular weights would be easier to manage. According to my plans, a pretty big chunk has to be removed from the back side of my weights.

Thanks
 
Get the lead out

I had problems with one of my elevators as well. The counter-balance skin wouldn't fit over the ribs, just as you described. The problem turned out to be the counterbalance weight. The portion of the weight that gets bolted into place between the rib ends and the skin was cast too thick. When I tried the other weight, the skins clecoed into place with no problems. Try to cleco the skin to the ribs without putting the weight into place. If they fit, the problem is your CB weight. If they dont, you might not have the proper 90 degree bend angle on the rib flanges.

I spent a lot of time grinding down the lead. It was difficult because of the concave shape that needs to be maintained to sit flush on the ribs ends. Eventually I got it down to the proper size and got things riveted together.

Here's a picture I took when I finally got it to fit. I must have spent a couple of hours trying to get this right.

Also, on the advice of others here on the forum, I am not removing any additional lead from the CB weights until final assembly.

dsc0506yu7.jpg
 
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Potential Gotcha !

brewtoo said:
Today I saw a couple of finished RV-7s. They both had simple rectangular lead blocks for elevator counterweights, mounted inside the rib.

Mine has a big molded lead piece that you install right out on the end of the counterweight ribs. It actually closes the end of the fiberglass tip. Which is the newer design? My kit is from 2001.

Looks like the rectangular weights would be easier to manage. According to my plans, a pretty big chunk has to be removed from the back side of my weights.

Thanks
Just make sure that if it's a 7 (I don't know about other models) you DO NOT get carried away and remove the "chunk" from BOTH weights......DOH ! I did a beautiful job on both of mine and didn't discover my mistake until I hung the elevators :rolleyes:
 
Me Too

flydjd said:
Just make sure that if it's a 7 (I don't know about other models) you DO NOT get carried away and remove the "chunk" from BOTH weights......DOH ! I did a beautiful job on both of mine and didn't discover my mistake until I hung the elevators :rolleyes:

Mind if I ask how you fixed it? Don't ask why I'd like to know!
 
Elevator counterweight fix

Caveman said:
Mind if I ask how you fixed it? Don't ask why I'd like to know!

Hi Caveman,

The fit of my counterweights was VERY tight and I doubt if the bolts are even necessary to hold them in position so swapping the "light" counterweight wasn't really an option as I didn't want to "Un-rivet" (not a real word !) the elevator....

So I called Van's who suggested adding extra weight by melting lead shot into a weight to add to the elevator arm.....in fact I just bought an old style oblong counterweight (6's and early 7's) from Van's, cut it in half and bolted it to the outboard side of the counterbalance arm using the tooling hole at the fwd end of the arm with the weight inside the tip for safety.....when I install the tips I will make a compartment to house it in if it were to come loose.
Not my idea but used by others with various ways of fixing (incl. using a platenut) ;) AND not yet seen and approved by my Tech. counsellor so all usual disclaimers apply............
 
Thanks guys,
I saved the hunk of lead and will either melt it down in a lead pot (for bullet molding) and see if I can find a secure way to attach it to the other portion of the weight or do something similar to what you did and attach it to the counterweight rib via the lightening hole. I was wondering if epoxy might bond it well enough to the other piece. I don't want to be a guinea pig though. I dang sure want it to be secure. I definitely don't want to try and remove and replace with a new one. That baby is in there! The rest of the empennage is complete except for the fiberglass. No other problems except a few monor errors, such as a handfull of rivets that needed to be drilled out and replaced. I'm pretty proud of it!
 
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