Rolled trailing edge

[mototopo]

I'm building a RV7 and I'm at the point when I have to roll the leading edge of rudder and elevators.

I started with the rudder and despite my efforts, I'm unable to obtain a perfect match of the holes. There is a certain amount of spring back that I have to fight to cleco the two skin together (a couple strips of duct tape helps to align the holes) . Well, I think it's normal, I just don't know how much spring back is normal and how much is too much.

Any suggestion? Do you remember which is the distance between the two skin before clecoing them together?

[Transporter]

Rolling the leading edges was a challenge. I followed some advice from a local builder that worked well for me:

1. Work with one short section of leading edge at a time-it's easier if you don't try to roll the entire edge of the rudder or elevator at one time. Start at the narrowest end and work toward the widest end.
2. Begin by rolling the edge that will be on the outside of the joint (see your plans) using an Avery or Cleaveland edge rolling tool or your hand seamers. A slight crease along this edge will help the edge pull tightly to the other skin when you rivet.
3. Place a piece of duct tape lengthwise along the edge. Stick the tape so that about half of the width of the tape is on the skin and the other half is exposed. Turn the control surface over on your workbench. Lay your pipe/broomstick/or other rolling "tool" along the exposed half of tape and stick it down to the tape. Make sure it's nice and straight along the edge to be rolled.
4. Turn the control surface over again and place additional short (6") pieces of duct tape at right angles all along the edge to stick the skin to the rolling tool. These tape strips will be pulling the skin, so overlap the tape as needed to make a strong attachment between the skin and the tool.
5. Turn the control surface over again on your workbench and roll the edge as needed using the tool. When the edge is curled properly the rivet line will be centered on the leading edge and the distance between the skin and the spar should be within 1/8" of the distance shown on the plans. You'll need to overbend the aluminum since it will spring back. When you're satisfied, peel the tape off the skin and the tool.
6. Repeat for the edge you want on the inside of the joint (see your plans). You will curl this skin so that it pops under the outer skin of the joint. Be careful as it pops under so the skins don't catch-take your time. If you have the curl right it will slide/pop under and then spring back tightly against the outside skin. Carefully pull the tape off the tool and slide the tool out of the leading edge.
7. The edges should now be tight against each other with little or no gap and the rivet holes will be aligned (or will be close enough so you can cleco). Put clecos in every hole.
8. Put narrow strips of duct tape between every cleco. This tape will hold the skins tightly together when you remove a cleco to rivet.
9. Remove one cleco at a time and rivet!
10. Remove the narrow tape strips and shape the curve with your hands as needed.
11. Repeat until you're done.

Note that it's possible to bend the skins too tightly. If you do, you risk putting a crease/kink in the skin as it goes over the edge of the spar-work carefully!

Good luck,
Mike

[lorne green]

If you're having issues with your tape ripping, a single strip (length wise) of "Gorilla Glue" brand duct tape is all that's required. Expensive, but remarkable
tack and tear resistance! I used one strip to to two leading edge control surfaces.

[mototopo]

...The edges should now be tight against each other with little or no gap and the rivet holes will be aligned (or will be close enough so you can cleco)...

Well, it looks like I have more work to do... thanks Mike

[DanH]

Claudio,
I may have posted this before, but....

When you twist the bar, the bar and sheet metal will try to rise up off the table. Instead of a nice constant radius bend, the sheet metal will bend less around the bar and more near the spar. The answer was a pair of homemade J-bolts used to clamp the rolling bar loosely to the table top. The control surface needs to slide forward as you twist the bar, so make sure your work surface is smooth. A sheet of any cheap plastic film will let it slip easily.

[airguy]

Nicely done, Dan. My rudder leading edge came out acceptable, but not great. I decided to leave it be for now and build the wings, once I'm finished there I'll have a much better feel for what I consider acceptable versus not, and I'll go over the entire empennage again with a more critical eye.

[mototopo]

Thanks Dan, I'll try this way.

[Rivethead]

Dan, That looks like a really good way to do the edge rolling. Where were you when I rolled mine?