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The Shop
RV-7 N8ZG
Empennage
Horizontal Stab
Vertical Stab
Rudder
Elevators
Fiberglass
Wings
Spars
Ribs
Wing Skins
Fuel Tanks
Ailerons
Flaps
Fuselage
Firewall
Center
Section
Bulkheads
Aft
Fuselage
Center Fuselage
Cowling
Engine
Paint
Aft Fuselage
Bending
the longerons wasn't particularly difficult, but did take some time. I
used scrap plywood from one of the shipping crates to make the template.
The process is rather simple - clamp the angle in the vise, lean on it and
smack it with a dead-blow hammer. Tapping won't cut it - you have to
HIT it. Losen the vise, move it a little, Cinch the vise, lean on it and smack it again. The
problem is that the angle stock tends to bend in more than one direction with
each hit. Check it often against the template and make adjustments
until it matches.
The
F-721B aft canopy deck parts are trimmed and modified differently for the
slider and tip-up canopies. After making the mods, I clamped the parts
to the longerons and match-drilled.
Fitting
the F-779 aft fuselage skin to the F-710, F0711 and F-712 bulkheads has been
the most frustrating part of the project. It's made from thick sheet
and is tough to bend with the tools I have.
I banged on it with a
hammer, clamped it in the vise and heaved on it. Hit it some more.
Grunted with the hand seamers.
Hit it some more. After many hours of obviously doing it wrong, I piled
the parts in the truck and trudged over to see Dan Horton. A few minutes
of making a series of shallow bends in the finger break had it all fitting
nicely.
The next step is to fit the WD-409 tail
wheel mount to the F-711 and F-712 bulkheads. Square it up on F-711,
clamp it in place and back-drill thru the bulkhead and HS attach bars.
Then
you're directed to cleco F-712 to the bottom skin, clamp WD-409 to F-712 and
drill two #40 holes for keeper rivets (the two clecos at the bottom center of
the frame). I'd recommend you not drill these two holes until you get
the parts clecoed back into the fuselage assembly. Without the whole
aft fuselage clecoed together, it's tough to get it all lined up and square.
I measured and marked the parts, clamped and measured again, stood back and
eye-balled, adjusted some more and finally drilled it. After riveting
F-712 to WD-409 and clecoing the F-779 assembly into the fuselage skins, I
wound up with significant twist that had to be taken out.
The aft portion of the fuselage gets big in a hurry, posing certain difficulties if you're working in tight quarters. The plans call for three identical saw horses upon which to build the assembly. I opted for milk crates because they are stable, light, easy to move or re-configure, stackable and put the work at a pleasant height. They're also cheap. Ask before you borrow them.
Begin
by laying the F-778 bottom fuselage skin across the supports and clecoing the
F-707and F-708 bulkheads to the skin.
Then
add the side skins and slip the J-channel stringers in place. Cleco in
the F-779 aft bottom skin and add the F-710, F-711 and F-712 bulkheads.
Trim
the aft ends of the stringers to fit around the F-711 and F-712 bulkhead
faces, then trim the forward ends to fit around F-706. Cleco F-706 to
the aft fuselage skins.
I
used scrap lumber and shims to level the assembly, then used plumb bobs in
the bulkhead tooling holes to check for twisting. With everything
squared up, I clamped and drilled the ends of the stringers, then
match-drilled the stringers to the remaining bulkheads. With the
stringers clecoed to the bulkheads, I finished match-drilling the spans
between the bulkheads, then reamed the skin-to-bulkhead holes.
Now take it all apart, pull any remaining plastic off the parts and de-burr all those holes. Then dimple all except the F-706 attach holes. I scuffed and cleaned the parts, then shot the joint lines with VariPrime.
Time for final assembly. I clecoed and riveted the F-712 bulkhead (with the WD-409 tailwheel bracket tack-riveted) to the F-779 bottom skin. This bulkhead was a beast to rivet. The shape of the assembly and the angles of the flanges, rivets and the bucking bar made it very difficult to get good, square shop heads. I drilled out a BUNCH of rivets trying to get it right. I can't find any pictures; I suppose I was too aggravated to think about it.
With F-712 riveted in place, I clecoed F-711 to the F-779 bottom skin. Slipped the bolts thru F-711 and WD-409 and ran the nuts down to barely snug and riveted F-711 to F-779. Riveting F-711 was just as frustrating as F-712.
I clecoed the aft side skins, bottom skin, stringers and bulkheads back together, then leveled and squared the assembly again. I started riveting the aft fuselage by setting the rivets where the bulkheads and stringers meet, then checked for alignment again. This is where I found the twist that was caused by the mis-alignment of F-711 and F-712.
Alli held the forward end down while I twisted the tail back into position - and sheared the two WD-409 keeper rivets. Suddenly, everything was nice and straight again, except for the gap that appeared between F-7-12 and WD-409. I'll drop a shim in later, and the bolts that attach the lower end of the VS spar will pull it all down tight.
I
set the rivets that join the stringers and bulkheads to the side skins and
riveted the F-779 bottom skin assembly to the side skins. Remember to
leave the bulkheads open above the F-786B stringers.
Alli
helped me rivet the bottom skins. She claims to enjoy helping me with
the project, and it's nice to have some company. She generally does a
great job, provided I can properly explain what I need her to do.
The
aft fuselage cone is complete.
Set it aside and make room for the center fuselage.