Gregmarlow

Gregmarlow

Well Known Member
Hello guys,

I'm building a 9A and on the fuselage book, page 8-6 of revision 9s8r5, 12/13/04 (this is my preview plan book reference, but they are the same), the NOTE about machine countersinking the skin through the bulkhead has me slightly confused.

Anyway, I think I figured this out by looking at the most common fuselage questions on the Van's web site, but I just want to be clear.

On the intersection of the forward bottom skin (972), the center bottom skin(976) and the 904 bulkheads, I should dimple the 972 skin, and countersink the 976 skin and 904 bulkheads to accept the dimple in the 976?

Won't that enlarge the hole in the 976 center skin unacceptably? It seems too thin to counter sink. I see in the web site that this is acceptable, but can't I dimple both skins to fit into a countersunk 904 hole? Then, the top of the 904 will still be flat to accept the 4 skin stiffeners.

On the 5 outboard rivets where they have to be double flush, I can see how this won't work, because countersinking both sides of the 904 would make it too thin. Here, the proscribed method of countersinking the center bottom skin into the 904 to accept the dimple of the forward bottom skin, and countersinking the top of the 904 as well to enable double flush operations would be agreeably best.

But what about the rest of the rivets, including the ones where the stiffeners have to attach? Any problem with dimple, dimple, countersink (skin, skin, 904)

Opinions on this? I have a question about this into Van's but this is probably a dumb question and someone out there with experience with this can clear it up for me.

Thanks in advance.
Greg Marlow
Fuselage
 
Answer

Well, since no one chimed in on this, I'll tell you what I figured out, and what Van's said.

They said to try it my way, Countersink the 904 bulkhead, and then dimple the two skins. They said let them know how it turned out. Well, that didn't sound too encouraging, so I went with the triple dimple method, and used a light countersink on the 904 dimples. That worked good for me.

As for the 5 outboard holes, I slightly countersunk the interior of the 904 because I've read on a few web sites that the gear mount doesn't come close to the rivet heads on those builders that elected not to double flush those rivets anyway. Mine will be slightly countersunk, just in case. As for the 4 rivet locations where the ribs mount, I used the recommended method of countersinking the center fuselage skin and 904 bulkhead together, so that they will accept the dimple of the forward bottom skin.
 
Gregmarlow said:
Hello guys,

I'm building a 9A and on the fuselage book, page 8-6 of revision 9s8r5, 12/13/04 (this is my preview plan book reference, but they are the same), the NOTE about machine countersinking the skin through the bulkhead has me slightly confused.

Anyway, I think I figured this out by looking at the most common fuselage questions on the Van's web site, but I just want to be clear.

On the intersection of the forward bottom skin (972), the center bottom skin(976) and the 904 bulkheads, I should dimple the 972 skin, and countersink the 976 skin and 904 bulkheads to accept the dimple in the 976?

Won't that enlarge the hole in the 976 center skin unacceptably? It seems too thin to counter sink. I see in the web site that this is acceptable, but can't I dimple both skins to fit into a countersunk 904 hole? Then, the top of the 904 will still be flat to accept the 4 skin stiffeners.

On the 5 outboard rivets where they have to be double flush, I can see how this won't work, because countersinking both sides of the 904 would make it too thin. Here, the proscribed method of countersinking the center bottom skin into the 904 to accept the dimple of the forward bottom skin, and countersinking the top of the 904 as well to enable double flush operations would be agreeably best.

But what about the rest of the rivets, including the ones where the stiffeners have to attach? Any problem with dimple, dimple, countersink (skin, skin, 904)

Opinions on this? I have a question about this into Van's but this is probably a dumb question and someone out there with experience with this can clear it up for me.

Thanks in advance.
Greg Marlow
Fuselage
Click to expand...

Greg,

I've ordered my Fuselage but I'm building a -9 not an "A". Having no knowledge of the area you're refering to, will this be something I will need to address or is this soemthing that only pertains to "A's"?

Thanks and keep us up to date with how it all comes out.
 
The reason why those outboard rivets are double flush is so they clear the lower flange on the gear leg weldment. I remember c'sinking through both skins and the centersection flange then set the rivets normally. I had 1 or 2 rivets scraping on the powder coated weldment. A little work with the Dremel took care of the issue.

Steve
 
Double flush rivets

....so if I understand this particular stage of the build proccess, this "double flush" riveting is only to allow for room for the gear leg weldments for the RV-9A?

Also, further thinking this thru, as a -9 builder, I only need to counter sink the F-972 and F-976 skins at the F-904 A & B bulkheads?

Right?
 
Robert M said:
Also, further thinking this thru, as a -9 builder, I only need to counter sink the F-972 and F-976 skins at the F-904 A & B bulkheads?

Right?
Click to expand...
Left. I mean, not right.

You CS that row because the flange and skins are too thick to dimple.

The Double Flush rivets are there so the gear leg weldments will lay in there properly.

Those of us who elected to take the path less traveled have to put in F-7114 L&R in that location. See drawing 34 for details.
 
Okay, so I still gotta double flush those 4 rivets on each side 'cause I gotta put a F-7114 on each side rather than the gear weldment?!
 
best method

Should I CS the inside of the F904 bulkhead to accomodate the double flush rivet?
 
Robert M said:
Should I CS the inside of the F904 bulkhead to accomodate the double flush rivet?
Click to expand...
I think so, this should allow the F-7114 will lay right on there.

You could put the F-7114 in place, using your wing pins to hold it in place and see if there is clearance under it.

I seem to recall, but I'm not positive that I may have put that in place riveted through the f-7114. I would have to pull my plane apart to verify this as I don't have any pictures of that area.

Give Van's a quick call and see what they have to say.
 
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