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Longerons

wirejock

wirejock

Well Known Member
I'm reading forward. At some point, the parts have to be disassembled for the usual prep work.
Question
Are the skin to longeron holes countersunk in the longeron for dimpled skin holes?
That looks right but I don't read it anywhere. It looks like the top skin is the same line of holes so two layers of dimpled skin holes and a row of countersunk holes in the longerons?
Now that I think about it, that would be the only option but I want to ask anyway.
There are other places where layers are countersunk but usually mentioned specifically.
 
Yes, you have it right Larry. Set up your stool and just move down the. Longeron as you countersink. Lots of sweeping up afterwards. A couple hole near the tail get threaded instead of countersunk for trim attachment with screws so check the plans for the location of those.

Jim
RV9a flying
 
Yeah, I am not looking forward to that job. I've been doing the lower and aux longerons on the front section, and still need to do all the skin stiffeners. Man, this bites.

How fast should I be spinning the countersink cutter, anyway? I chuck it in the electric drill because the air drill just seems way too fast for that job. I run it pretty slow, maybe a few hundred RPM.
 
Countersinks

DaleB said:
Yeah, I am not looking forward to that job. I've been doing the lower and aux longerons on the front section, and still need to do all the skin stiffeners. Man, this bites.

How fast should I be spinning the countersink cutter, anyway? I chuck it in the electric drill because the air drill just seems way too fast for that job. I run it pretty slow, maybe a few hundred RPM.
Click to expand...

Thanks Jim.
Dale
I use an electric variable speed for that reason. Slow with a single flute cutter. But I'm no expert. That's why I stay behind you.:D
 
I'm in the disassembly and prep stage so will be quickly upon the c/s'ing of the longerons.

Jim, are referring to dwg. 44 where the empennage fairing attaches using the AN507 screws? It states to use the prepunch holes in the F-773 skins as locators.
 
Empennage

That is what Jim is referring to in his post. The plans do not tell you, but if you look at the empennage fairing drawing you will see several rivet holes that are tapped for screws.
 
DWG 44

sahrens said:
That is what Jim is referring to in his post. The plans do not tell you, but if you look at the empennage fairing drawing you will see several rivet holes that are tapped for screws.
Click to expand...

Looks like DWG 44.
If I read correctly, there are nine places each side are drilled #36 and tapped #6-32 for the empennage fairing attach. That tells me those holes in the side skins should not be dimpled. But which nine are they? I don't have an emp fairing to locate them.
The confusing part is the rivet callout on DWG 28 is AN426AD3-5.
Also, what is attaching to the upper forward tab on F-712?
Is this another one of those "do as I say, not as I do" Vans moments?
Totally confused.:eek:
 
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A lot of people don't end up using all of those screw holes anyways Personally, I never got the memo and riveted all of mine. When it comes time to install the emp fairing, no big deal, I can drill out a few rivets. I've had plenty of practice by now. Enlarging for screws will remove most of the dimpled area, which will be covered by the fairing anyways.

Chris
 
Holes

YellowJacket RV9 said:
A lot of people don't end up using all of those screw holes anyways Personally, I never got the memo and riveted all of mine. When it comes time to install the emp fairing, no big deal, I can drill out a few rivets. I've had plenty of practice by now. Enlarging for screws will remove most of the dimpled area, which will be covered by the fairing anyways.

Chris
Click to expand...

That sounds much easier than trying to spot 18 holes.
 
Here is an example

I riveted all of them and then went back to drill out and tap where I wanted screws. It was a little tight working under the HS but doable. You can count rivet locations on DWG 44 to determine which rivets to leave out.

Empennage%20328_zpsqnfzx7k5.jpg


I placed four screws under the HS and six total on each side, there is one screw not installed in this photo. This is a Fairings-etc fairing, not the Vans supplied fairing.
 
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Ha! That is what I was thinking and also how to support that flimsy awkward part. The better half might get upset if I use the hood of her car for support.
 
aeroaddict said:
Ha! That is what I was thinking and also how to support that flimsy awkward part. The better half might get upset if I use the hood of her car for support.
Click to expand...

Sure! just throw a blanket over it and start drilling, 15 min should be enough time........
 
I like to run a streak of boelube down the row for countersinking, makes me think it goes faster, although not sure about the reality
 
Sorry to revive this but I'm in the same spot (roughly) and have questions (don't we all...)

Just finishing up first assembly of the fwd fuse and have the longerons drilled & cleco'd in place. Do I countersink it now and dimple the rear fuse lower skin or wait till I have drilled the rear fuse top skin? I.e won't countersinking/dimpling make it harder for me to match-drill the top fuse skins?
 
MeAndMyToys said:
I waited until i had the top skin fit and drilled before I countersunk the longerons and dimpled the lower skin.
Click to expand...

So you fit the top skins before you removed the longerons for countersinking, or did you countersink the longerons in place?

I dimpled the aft side skins after removing the longerons for countersinking. I used standard, tank, and substructure dies depending on how deep a particular skin is in the stack up, and set the countersink depth according to the die set used on the skin immediately adjacent to the longerons. I did some experimenting with scrap and came up with various countersink settings depending on the skin thickness and die set used: http://mykitlog.com/users/display_l...r&project=2052&category=7845&log=193987&row=3

My plan for the aft top skins is to drill, deburr, and dimple the holes along the main longerons off the airplane. I already know that those skins fit, as I clecoed them in place prior to the cross country move.
 
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