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  #61  
Old 04-24-2018, 07:54 PM
David Paule David Paule is offline
 
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,063
Default A Firewall Detail and a Spar Bulkhead Fitting Issue

There are two areas in the assembly of the firewall and the spar bulkhead build-up where a builder might make an error like I did.

The first is on the bottom of the firewall. There's a 3/4 x 3/4 x 1/8 angle that gets riveted to the firewall. It should NOT be flush to the flange. Instead, don't forget to allow a .040 gap for the F-321 forward belly skin.

Here's what it will be when you're done:



Yeah, I didn't pay enough attention there and made mine flush. I added some room for the skin by making a short piece of .040, beveling the forward edge, and used a clamp, with a block of wood against the firewall, to force it in. The flange is ductile and bent up to allow the strip to fit in.



It didn't take much tooling. The hammer let me tap the flange flat again and that was easy. The marker let me keep track of where I was, and the mirror was handy to make sure the .040 strip was seated.



The second area is the bottom of the F-303 spar bulkhead. This doesn't really affect the spar bulkhead itself, but the lower longeron parts and the F-312 firewall ribs need to be made to fit this correctly. The main thing is the height of these parts. They need to be flush with wherever the F-321 forward firewall skin lays on the spar bulkhead assembly as it's being built. I had to redo mine, since I didn't get it right.

Remember that right in the center, the seat belly skins overlap at the dihedral break. That won't affect the lower longeron and F-312 fit-up, but it will affect the F-321 forward belly skin itself, which has a compound curve there.

Here's how it should be. (And here I'm referring only to the forward lower longerons).



Dave
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  #62  
Old 03-16-2019, 03:34 PM
David Paule David Paule is offline
 
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,063
Default Instrument Panel Dimensions

The drawing isn't accurate. Here's what I started with. Then I used some curves and faired it from there. Seems to be okay.

0 and 9.67 or 9.65

1 and 9.65

2 and 9.56

3 and 9.38

4 and 9.12

5 and 8.77

6 and 8.33

7 and 7.82

8 and 7.18

9 and 6.37.

The remainder are fine.

I made my panel 1/2" taller than stock, all at the bottom, and still had 3.7" to the stick. That's without a stick grip, though. YMMV. The dimensions above are to the stock panel bottom, not my extension.

Dave
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  #63  
Old 02-17-2020, 08:17 PM
David Paule David Paule is offline
 
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,063
Lightbulb Aft Deck

The F-319 aft deck has two access and lightening holes and one clearance hole.



The clearance hole is the aft rectangular one, on the right of the part here on drawing 22. I haven't figured out if the left and center holes are functional or intended for access. So far I don't see anything that suggests that the left and center holes are functional. The rightmost hole allows for the elevator bellcrank, as shown on drawing 26.

The positioning of the three holes should be determined after the fuselage is assembled and the horizontal stabilizer fitted in place. It doesn't need to be completely aligned or mounted for this, you're ensuring that you have solid material where the forward stabilizer spar attachment goes. But fuselages vary and yours might - or might not - be exactly per the plans. Mine wasn't. And the plans for this part might - or might not - be exactly correct.

Incidentally, I'm sorry that so many of my previous images have been lost.

Dave
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  #64  
Old 02-17-2020, 09:54 PM
sf3543 sf3543 is offline
 
Join Date: Jan 2005
Location: San Antonio, TX
Posts: 1,093
Default

The two access holes allow you to access the rudder cable where they exit the fuselage skin, the elevator torque tube at that end, the tailwheel spring retaining bolt ( I?m pretty sure) and any other wiring you may have going to the tail. Also allows you to inspect all the rivets in that area. Which is not a bad idea since those skins can take some abuse from the tailwheel.
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Steve Formhals
A&P, Tech Counselor & Flight Advisor
RV3B
Legend Cub
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  #65  
Old 02-18-2020, 10:01 AM
David Paule David Paule is offline
 
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,063
Default

Exactly. They allow access but the precise position isn't necessary for anything to function.

Dave
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  #66  
Old 03-18-2020, 09:39 AM
Chillibob Chillibob is offline
 
Join Date: Mar 2017
Location: Chillicothe, Ohio
Posts: 9
Default Clarification on Center Section Rear Spar Attachment

I am reviving an old RV-3 project that has been dormant for years. I need to implement to two change notices. My wings are the Type I. In looking at CN-1, it suggests there were two types of rear spar attachment pieces, the older one was for kits supplied before Sept. 1981 and calls for a 1" x 1" x 1/8" 6061-T6 angle attached to F-305. The newer kits called for a 1.25" x 1.25" x 3/16" 6061-T-6 angle. My plans and kit called for a 1.25" x 3/16" 2024-T4 bar instead of an angle. My piece is clecoed in right now so I can easily change it but after looking at pictures on this forum from some of your projects it looked like a lot of you also had bar instead of angle. Any thoughts on which is correct or at least which is preferred?

Bob Anderson (Chillibob)
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  #67  
Old 03-18-2020, 10:41 AM
David Paule David Paule is offline
 
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,063
Default

I think this is probably a question for Van's. Without knowing more about the joint between the wing spar and the F-305 carry-through, it's hard to comment. But I can confirm that my RV-3B does use the flat 2024 bar.

Dave
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  #68  
Old 03-19-2020, 05:21 PM
Chillibob Chillibob is offline
 
Join Date: Mar 2017
Location: Chillicothe, Ohio
Posts: 9
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Thanks David. I will contact Van's. Do you know of anyone that is actively working on 3B currently?
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  #69  
Old 03-19-2020, 06:52 PM
David Paule David Paule is offline
 
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,063
Default

Well, I am, and here's my VAF blog. I'm going back out the the shop again in a few minutes. Wings mostly done, control surfaces done, tail done, fuselage past the canoe stage, working on the canopy installation now.

There's one in Central CA and one down under that I know of. There are a couple others, too, scattered around.

Dave
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  #70  
Old 03-19-2020, 10:02 PM
RV3Bob RV3Bob is offline
 
Join Date: Jan 2008
Location: Los Altos, Ca.
Posts: 64
Default

Chilibob.

I am building a 3B. Almost done. Concerning the rear spar carry through there have been issues. The design I believe calls for a 1.25 X 3/16 bar. This can cause edge distance issues when drilling hole for attaching wings. Many comments from builders suggested going to a 1.75 X 3/16 bar which is what I did. Worked out great.

Bob Grigsby
Hunkered/Sheltered in place
Los Altos Ca.
J3 Cub. Down for annual
3B close. I think
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