Since the last update I primed the mating areas on the inside of each rudder skin, then primed the stiffeners. Didn’t have time to mix up some two-part epoxy, so I shot the stiffeners with some Tempo zinc chromate I had lying around the shop. Then it was time to set everything up for back-riveting.
Rudder skin with rivets taped in place
Don’t all those little rivets look cool? It’s much easier to do all the rivet insertion at once and tape ’em into place with removable scotch tape.
Back-riveting a rudder skin
And here we go with the back-riveting. The primer application is my attempt to (a) limit the amount of hideously expensive primer that I’m using, and (b) not add as much weight to the tail. Some notes on back-riveting – there are a couple of different back rivet sets available. Some spring-loaded sets have a large Delrin sleeve that’s really too big to fit in tight places (like between these rivets and the adjacent stiffener angles). I have another one from my old RV-6 days that has a narrow metal collar. I put some hockey tape on the end to protect the surface – works great! [21 Dec 04 – Note from the future…a couple of extra hits on the rivets next to the trailing edge will flatten out the shop heads just a little and reduce the chances that they will cause problems when closing up the trailing edge. Right before I prosealed the TE, I had to squeeze these rivets a bit more because they were keeping the edge from seating properly].
One other communique from the primer wars – the Tempo zinc chromate doesn’t seem to be very durable. Even when applied over alodine, and when using tape on the back rivet set, some of the primer still wore off during riveting.
Back-riveting complete on the left skin
Here’s one rudder skin done…
Back-riveting complete on the right skin
…and the view from the other side. Another bit of info I’ve learned while trimming the blue plastic off these skins is that Van’s is spot-on when they say that the plastic gets harder to remove if it stays on for a long period of time. If I weren’t so obsessive about this stuff, I guess it wouldn’t matter that the plastic looks like crap.
Lots of little tasks on the rudder stiffeners and skins were taken care in the last week. Right rudder skin stiffeners were cut and trimmed, then stiffeners for both sides were edge-finished and dimpled. One thing I learned from Gus at Van’s is that the reference holes used to trim stiffeners, don’t need to be removed – so I didn’t do that on the right stiffeners as I did on the left ones.
[17 Jan 05 – Note from the future…Van’s calls for these holes to be removed from the elevator stiffeners. Call them if you’re not sure what to do – maybe that will get them to standardize their plans/instructions.]
Rudder stiffeners prepped with the Touch-n-Prep pen
Before priming the stiffeners, they needed scuffing and alodining. I hate alodining…it’s a messy, nasty, potentially toxic process. So I was really jazzed to find Touch-n-Prep pens. These things are the berries…they’re like magic markers full of alodine 1132. Just coat the parts, and let them dry – no rinsing required. I got mine from Stein Bruch at SteinAir. Stein is great…he’s selling these things cheaper than anyone else, and I got mine a day or so before he said it would arrive. I used the pen to alodine these stiffeners, and the only waste was a couple of pairs of nitrile gloves. No contaminated dip water, no mess all over the floor – freakin’ fabulous!
Rudder skins prepped with the Touch-n-Prep pen
Here are the skins scuffed and alodined. This would have been a lot more messy with the old process of alodining. Next step is to prime the stiffeners and skin rivet lines, then back-rivet the skins and stiffeners.
While the horizontal and vertical are awaiting inspection, I’ve started the rudder. I spent three hours or so studying the plans, then cutting stiffeners for the left rudder skin from the raw material provided.
Left rudder skin with stiffeners
I had to read through the plans a couple of times to properly interpret how cuts are made between the prepunched holes. A bandsaw and belt/disc sander really speed up the trimming/shaping process. I didn’t like the little half-hole left where the stiffener taper is cut, so I used the belt sander to round off the corner a bit.
Hitchhiker’s guide quote
One of my co-workers handed me this message today which he found in a piece of biscotti. I’ve never heard of “fortune biscotti” before, but it seems as though Mama has been reading “The Hitchiker’s Guide to the Galaxy.” This little tidbit had to get posted in the shop.