Rudder trailing edge riveting?
 

I am getting ready to rivet the rudder (7A) trailing edge. I am not sure how to proceed. What tool do I use to set the rivets? The instructions say something about a mushroom set and I am not clear what that is. Is it the cupped rivetting head for the gun that is normally used on the factory head ends of AN470 rivets or is it something else? Or do I use the backrivet set and tilt it parallel to the upper skin as I set the rivet?

Also - I followed the instructions that said to use either fuel tank sealant or a good epoxy to hold things together. I used the epoxy and it broke apart as soon as I moved the rudder. Do I really need to glue this before attempting to rivet?

The way this rudder is going so far I may have to build a new one.

Very confused. Please advise.

Thanks in advance,

-- John

Most of us use tank sealant if anything on the trailing edge. Some epoxies can get very brittle. This is where tank sealant really shines. It has a long working time and stays flexible. Still, it shouldn't have come apart just moving the rudder. It was either mixed incorrectly or the surfaces were very dirty. I'm guessing it was just mixed wrong. Also, how long did you wait? Epoxy in a thin film takes FOREVER to cure. Like, 24 hours. The stuff in the cup will be hard as a rock but the thin film can still be a long way off.

re: setting the rivets...

Use a "mushroom" set and backrivet it. This is the same set you use to do the flush rivets on the skins.

Read through the instruction 2 or 3 more times, check out some of the builder sites and you'll be fine. Better yet, get an experienced builder to help you. When you redo it with tank sealant, if that's what you decide, put a layer of Boelube down on the long aluminum angle as you cleco it down. It'll make releasing it much easier if a little sealant squeezes out.

I built 2 rudders too :)

edit: and YES, follow the instructions and start with the back rivet set as everyone says. I was just trying to clear up the reference to the mushroom set!! The wording made it seem like "use a mushroom set on the shop heads". I did that the first time and it worked but it was difficult!

The instructions for my 9 mention starting with a back rivet set. You set the rivets half way with this using a rolling technique. This is where a rivet gun with a teasing trigger comes in handy. Start vertical, or straight down on the rivet, and as your setting the rivet, roll the gun into the wedge angle. Once the rivets are started or half set, using the back rivet set, you switch to a mushroom set, or in my case a swivel mushroom set.



This is a photo from Avery's Site... averytools.com
SKU#: 1047

Hope this helps...

John here is what I did.
 

I didn't use any glue. I used a backing plate of 3/8 steel that was polished on one side. Put the rivets in the holes and taped them in place. I think that I may have had cleco in the end holes to start with. Placed the rudder on the back rivet bar and clamp in place making sure the the rudder/rivets were being held flat (to the skin). Now use the back rivet tool and partially set the rivets. I needed to reposition my back rivet bar to finish off each end where I had it clecoed, making sure everything is flat.
Now flip it over and use the mushroom set (or flat set) on the top of the rivets. This will finish smashing the rivets into the dimples. The back rivet bar should be under the rudder at this point. Make sure that the rudder is clamped down and remains flat (to the skin angle).
You will end up with some area in the shop side of the dimple that is not filled in. I tried to use a larger rivet then was called out for on a couple of holes to make a better fill, but this didn't turn out so good, so I would recommend keeping with what Vans calls out.

Kent

I just followed Van's instructions and it came out great. Used tank sealant, cleco'd to 1X3 alu angle for a week before back riveting.

I didn't use fuel tank sealant as I am building a QB and didn't think I would ever need the stuff and didn't want to stop and wait for Aircraft Oak to send me some.

I used an epoxy "with a 30 minute setting time" from Home Depot. The epoxy claimed to be appropriate for metal. I used the whole tube into the blister pack so it must have been mixed correctly. I applied it moderately from the blister pack to the AEX wedge and slid the wedge into place. I clecoed it all together with the aluminum angle (also from HD) and let it sit for about four or five days.

When I unclecoed it and moved it it broke - the epoxy just didn't have any hold to the metal.

"Mushroom set" - I guess that is what confused me. You mean the backrivet set which I used to backrivet the stiffeners to the rudder skins. That I can do. Boy, I bet it would have really been bad if I had tried to backrivet with the cupped driver!

So far the edge looks pretty straight when clecoed before riveting. I guess we will see what happens after I rivet.

I have looked at several other RVs rudders and some apparently have the single skin bent in the middle rudders. That just seems to me like it must have been a lot easier and just as good aerodynamically...

--JCB

I'll second Bills comments... I followed the instructions and it came out perfect. Actually, I think this is the only part of my airplane that has ever come out perfect. :eek: :D

IMHO, gluing it is the only way to ensure the TE comes out straight... I wouldn't attempt this without gluing it, but that's just me. I started the rivets with the back-rivet set, then flipped the rudder over and finished them against the back-rivet plate with the mushroom set. I don't know if they will help, but I have some pictures here and here. Good luck!

I just finished up my rudder trailing edge, and it also came out really nice. My process was:

Scrub with scotchbrite pads
Clean with MEK.
Apply RTV to the stiffeners, and Proseal to the inside of the trailing edge.
Insert the wedge and celco all holes to a piece of angle aluminum.
Let sit for 1-2 weeks. (not by choice) :-)
Remove clecos and angle aluminum.
Clean off extra dried sealant with my fingernail and MEK.
Tape rivets in hole.
Back rivet, in a random method, with just 2 cycles of the rivet gun.
Continue to back rivet in a random method till rivets were almost completely set.*****see below
Flip over, and use a flush set and hit each rivet again in a random order.

****Word of caution make sure you've got the rivets set far enough before you flip over the rudder. I had a few rivets where the factory head popped out of the dimple since the shop head wasn't set far enough. (this was on rivets that were in the close proximity of where I was using the flush set).

Also, knowing what I know now, I'd just go buy a big back riveting plate that is large enough to do the whole rudder, and also big enough for the wing's control surfaces.

Ryan

Ryan, only the -9 has riveted TEs on the wings... if you're done with the rudder for the -7 then you're done double-flush riveting (as far as I know). :)

I used Tank sealant thinned with Toulene and brushed it on. Once put together I set it aside for a couple of days. Follow the instructions on riveting and you should have no problem. This one came out dead arrow straight. Note I used two angle aluminum one each side.