The Murphy Builders Site

Ben
The inside bulkhead flanges are certainly not overly large on the
corners but I riveted through them and both corner wraps at the joints.
I think there may have been at least one place that I joined two corner
wraps immediately ahead of, or behind, a bulkhead but I still rivetted
the wrap to every bulkhead and joined all the corner wraps front to
rear. One would think that it shouldn't matter very much what you do if
these are the rear inside floor and corner wraps that are optional?
Ken L.

bransom@dcsol.com wrote:

On the rear fuselage section it is unclear to me whether each corner wrap
should be riveted to the previous one where they overlap. There isn't enf
material on the inside bulkhead corners to rivet to, but still, the wraps
could be riveted to each other and make things a little stiffer.
Opinions/Suggestions?
Thanks,
-Ben

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Hello Ben:

When I did all of my corner wraps, I used the clear sheet plastic method to
locate the holes at the narrow bulkhead corners. When drilling, I was very
careful and hit the exact centerline of the bulkhead flanges. I got my marks
located, centerpunched (actually, I used an Exacto knife and spun it in my
fingers to get an accurate dimple) and used a 1/16 inch drill bit first. I
hit every one dead center. It doesn't leave much edge distance at the narrow
points, but when you rivet the three plys of aluminum together (the 2
overlapping skins and the bulkhead flange, not to mention the epoxy) it
holds great so I don't think it is going anywhere. Also remember that some
builders elect not to install an aft floor at all, so structurally I am
comfortable with it. Also, there are a million other rivets holding things
together back there.

A lot of work, but a lot of piece of mind. FWIW.

Over-and-out . . .

Terry Dazey
Rebel 662
Lake Tapps, Washington USA

From: Ben Ransom
On the rear fuselage section it is unclear to me whether each corner wrap
should be riveted to the previous one where they overlap. There isn't enf
material on the inside bulkhead corners to rivet to, but still, the wraps
could be riveted to each other and make things a little stiffer.

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Ken, Terry,
Sounds good. I'm betting I can hit centerline on the inside bulkhead
curves, so will take that route. Thanks a lot,
-Ben
p.s. this summer is being a very slow building time for me --- daughter #2
getting married next week and although i'm terribly happy about that, my
rebel time is down to a few brief blips. looking forward to a more boring
schedule.



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Actually I didn't aim for the centerline but rather as far from the edge
as I could without hitting the face of the bulkhead.
Ken

bransom@dcsol.com wrote:

Ken, Terry,
Sounds good. I'm betting I can hit centerline on the inside bulkhead
curves, so will take that route. Thanks a lot,
-Ben
p.s. this summer is being a very slow building time for me --- daughter #2
getting married next week and although i'm terribly happy about that, my
rebel time is down to a few brief blips. looking forward to a more boring
schedule.

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My standard bulkhead flanges at the widest point are approx. 5/8 inch wide
measuring from top. A centerline on that flange would put the hole center at
5/16 inch. Great edge distance!

Measuring the flange area at the corner radius (cornerwrap area), the flange
necks down to approx.. 7/16 inch (3/8?) depending where you measure (again,
measuring from top). With that in mind, I drew a centerline on this narrow
flange. I then took into consideration and mentally deducted the thickness
of material (.025), minus 1/16 or so for the inside radius (I don't like
drilling holes too close to radius) and kept in mind that a #30 hole will be
drilled on this centerline. Rivet end expansion/mushroom to approx. 3/32
inch diameter was also taken into consideration. That would keep the rivet
expansion/mushroom1/32 inch away from the radius. This would make the final
edge distance approx. 1/8 inch. That is if you can hit every hole exactly
(which was my main goal) and the flange was a consistant width, which mine
is not. Other considerations I factored, were the shear that these specific
rivets would see, distance between said rivets, quantity of rivets holding
these parts together, the epoxy primer (very, very minimal) and the
thickness of the final riveted areas. Factored at the overlap areas were
three plys of aluminum (included two overlapping with good edge distance)
and spanning the length of the cornerwrap radius. Total thickness of these
three plys is a little over 1/16 inch thick (.065 inch), it seemed to me
that my 1/8 inch edge distance wasn't something I was going to worry about.
I also took into consideration where, at the corner radius, there were two
plys of aluminum (worst case at .045 inch thick) and 1/8 inch edge distance
didn't seem a major problem to me.

That is what my calculations were anyway. Geez . . . all of that was many
years ago!

Now one might be able to use a 3/32 inch Cherry Rivet in lieu of #30 Avex
which would give one more edge distance?

Enough rambling.

Over-and-out . . .

Terry "I am going to sleep good tonight" Dazey
Rebel 662
Lake Tapps, Washington USA

Actually I didn't aim for the centerline but rather as far from the edge
as I could without hitting the face of the bulkhead.

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I drilled #40 holes in the bulkhead corners first and removed the outer
corner wrap to back drill the inner wrap[ through the bulkhead.
Another option, but be sure you maintain the fuselage in alignment if you do
it this way.
Jesse

From: Terry Dazey <dazey@earthlink.net>
Reply-To: <rebel-builders@dcsol.com>
To: <rebel-builders@dcsol.com>
Subject: Re: [rebel-builders] rear fus inside corner wraps?
Date: Tue, 08 Aug 2006 13:58:23 -0700

Hello Ben:

When I did all of my corner wraps, I used the clear sheet plastic method to
locate the holes at the narrow bulkhead corners. When drilling, I was very
careful and hit the exact centerline of the bulkhead flanges. I got my
marks
located, centerpunched (actually, I used an Exacto knife and spun it in my
fingers to get an accurate dimple) and used a 1/16 inch drill bit first. I
hit every one dead center. It doesn't leave much edge distance at the
narrow
points, but when you rivet the three plys of aluminum together (the 2
overlapping skins and the bulkhead flange, not to mention the epoxy) it
holds great so I don't think it is going anywhere. Also remember that some
builders elect not to install an aft floor at all, so structurally I am
comfortable with it. Also, there are a million other rivets holding things
together back there.

A lot of work, but a lot of piece of mind. FWIW.

Over-and-out . . .

Terry Dazey
Rebel 662
Lake Tapps, Washington USA

From: Ben Ransom
On the rear fuselage section it is unclear to me whether each corner

wrap

should be riveted to the previous one where they overlap. There isn't

enf

material on the inside bulkhead corners to rivet to, but still, the

wraps

could be riveted to each other and make things a little stiffer.

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FWIW I believe the risk of too little edge clearance is mostly that the
flange will crack between the hole and the edge. The hole would likely
stop the crack but then the rivet can pull through and provides no real
strength. I was trying to hint that I'd rather keep as much of the
minimum recommended 1/4" edge clearance as possible rather than aiming
for the flange centerline. I guess we've beaten this one to death...
Ken L.

snip

Actually I didn't aim for the centerline but rather as far from the edge
as I could without hitting the face of the bulkhead.

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