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

David Paule 03-03-2015 09:32 PM

Top Skins Riveted
 
Both top skins are riveted to the wing frames.



I made a Vee frame to hold the ailerons in position during assembly. It's like the fixtures used for the empennage control surfaces. This photo shows it being checked for straightness. I'm using a laser level and you might be able to see the beam on the fixture.



Much earlier I'd trimmed the narrower of the aileron hinges per the plans, except that I'd misread the fractional part of the dimension and used 32s instead of 16ths. Oops. I sent to Van's for a new pair. I also needed some aileron ribs which had somehow not been included in my kit. These all arrived and are on hand now.

Dave

David Paule 04-11-2015 09:19 AM

This is my busy season and progress has suffered as a result. I've started the ailerons and made a jig to match-drill the stiffeners. I thought it would be easier than trying to keep track of them individually. Here's the simple jig. It's a piece of .093 steel with a short aluminum flange riveted to it above the bend in the stiffener, so I could reference the flange for location.



Here it is in use.



I made the lightening holes in the aileron spar with a brand new hole saw. I was a bit worried that the hole saw would wobble as it got close to cutting through the spar, so I replaced the pilot with a steel bar and pre-drilled pilot holes in the spars. I also pre-drilled a pilot hole in a piece of plywood, the backing piece, and lubed it:



This worked well and it only took a few minutes to make all the holes. My drill press has a minimum speed of 500 rpm and the hole saw preferred 295 or so, according to what I could find on-line, but 500 rpm was okay. I used a sanding drum to smooth the holes.

Next, I massaged the end ribs to fit. As delivered, the taper wasn't quite right. At first I thought the ribs were too long but after adjusting the taper, they seem to fit okay. What I had to do was reduce the distance between the two flanges at the aft end.

I first used a soft hammer and a round mandrel, a round bar, to put a bend in the web at the very back, then my Matco flanging pliers to gently squeeze the flanges together. That left the flanges having curved top and bottom surfaces, which won't do, so I used a tapered, rounded wedge of maple in a vice and formed the flanges a bit. Not hard and it seems to have done the trick.

That's as far as I've gotten.

Still have to drill the skin for the stiffeners, that's going to be awkward since the RV-3B aileron skins are one-piece and wrap around. Anyone have any thoughts?

Dave

David Paule 04-16-2015 09:03 PM

Drilling Aileron Skins and Stiffeners
 
The top surface of the ailerons was the tightest.



I bought a 90 degree angle drill for the job. It's still tight. I had to use a shorter bit, which I'd also gotten, for the aft holes.



The bottom side was a little easier. Not much, but a little.



Dave

gasman 04-16-2015 10:07 PM

Quote:

Originally Posted by David Paule (Post 974411)
This is my busy season and progress has suffered as a result. I've started the ailerons and made a jig to match-drill the stiffeners. I thought it would be easier than trying to keep track of them individually. Here's the simple jig. It's a piece of .093 steel with a short aluminum flange riveted to it above the bend in the stiffener, so I could reference the flange for location.



Here it is in use.



Anyone have any thoughts?

Dave

Nice drilling jig Dave. Why didn't you use it to help you drill (locate) those hard to reach holes in the skin?

David Paule 04-17-2015 10:47 AM

Hah!

I thought about and it was worth doing it this way for the certainty of knowing I had the stiffeners in the correct locations.

With double-flush rivets, the tool could have been used externally and that would have been the alternative. No point using the tool inside the skins since I had stiffeners already drilled - they were good for this match-drilling.

Dave

gasman 04-17-2015 12:42 PM

With all but the last two drilled in the stiffeners and the skin, cleco the stiffener in place with the drill jig on the outer surface of the skin. Drill the skin and stiffener at the same time undersize and then ream for no burs.

David Paule 04-17-2015 04:14 PM

Yeah, that would do it. I'd have still needed to double-flush the rivets.

Except now that I've got that 90 degree angle drill, and one aileron is drilled, I know that it'll take less than an hour to do the other, with much less handling on the .016 skin.

One thing that a builder has to be aware of is that there are often several ways to do something. I aim for a way that I know will do the job. As you can see from this blog, I'm not adverse to building and using jigs or tooling or for that matter, buying tools.

I'll get there - might not be soon of cheaply, but I'll get this done.

Dimpling and riveting are going to be fun, aren't they? Any suggestions about those?

Dave

David Paule 05-01-2015 10:45 AM

Fear
 
That and generally being kinda busy are why I haven't bothered testing my fuel tanks (RV-3B slow-build) until now. So I decided to get going on this today.

The right tank was already set up. I put in some colored water and pressurized the tank. Or tried to - it leaked out almost quicker than I could put it in. I stopped before a vacuum developed in the tank, the air was so eager to escape. I could hear the leak at the fuel cap. A couple pieces of duct tape later, the cap was more or less kind of tight.

In egregious disregard for all wisdom, I used my air hose to fill the tank. My bike pump didn't seem to be up to the job and I didn't feel like buying another. I've got two lines, a 90 psi and a 20 psi line. They are color coded. I used the 20 psi line to fill the tank and before I duct-taped the cap, it wouldn't even hold one psi. Afterwards, it took about four or five seconds to reach one psi. There was plenty of time to pull the hose off the tank and I could easily control it to a couple inches of water or closer, just no problem at all. But you do want to keep an eye on it.

Anyone know how to adjust the Deluxe Locking Caps? Don't be bashful. If you have any thoughts, please chime in here.

Back to the air. In it went and it seemed to settle happily in the tank. A big improvement there. When I looked at it more closely I could see that it was still leaking, though. I measured a loss of 22 inches or water pressure in 40 minutes. Since I'd only put about 27 inches in the tank, that meant that the new air was almost as unhappy in its new home as the old air was. And worse, since I couldn't hear it, I'll have to do a soap test to see where my problems lie.

There aren't any new photos for this -- fleeing air is so darn hard to catch.

That was the right tank. I'll get to the left one of these days.

I've done a bit of vacuum-bagging of composites, and generally duct-tape the perimeter of the bag. It's usually reliable to about 9 psi. At my elevation we have about 12.5 psi available. This is with the vacuum pump running continuously. Therefore, duct tape is good but might not be good enough here. On the other hand, the duct tape might be absolutely perfect. During vacuum bagging there are other materials in play which could potentially leak too.

I'm using real cheap duct tape.... FYI.

Dave

David Paule 05-02-2015 07:46 PM

Okay, the Deluxe Locking Caps use a nut that takes a 10 mm wrench. A socket is best but there's room for an open-end wrench. It doesn't take much to tighten the cap. Now that right tank is holding air.

Whew!

I'd tried to use duct tape to stop the leak. That only worked in a relative sense. It wasn't worth much for tiny leaks, which is what I seemed to have once I'd put on enough duct tape. So I ripped it off, nice and satisfying that was, and found that simply tightening that darn nut was sufficient.

I'd gone over the joints with soapy water and the only bubbles had been at the duct tape....

Looking ahead to when the plane is flying, I've been keeping a maintenance manual. In it are the things like the 10 mm wrench being useful for tightening the fuel caps, how to remove the landing light assembly, the correct sequence for pulling the landing light assembly out of the wing, what sealant the landing light lens uses, and that sort of thing. The manual is a single reference source for these things, so that I won't need to browse through my build notes - which might not be available when I'm out flying somewhere.

Dave

longranger 05-04-2015 02:21 PM

Quote:

Originally Posted by David Paule (Post 979457)
...

There aren't any new photos for this -- fleeing air is so darn hard to catch.

...

That's what the soapy water is for, Dave.:D


As far as I'm concerned, the manometer is just for telling you when you've reached the test pressure, and to serve as a relief valve if you get carried away. There are too many variables to account for to use it as a definitive leak indicator. Even if it does indicate a leak, you still have to find it...


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