SECTION 8: THE FUSELAGE
The RV-6/6A fuselage is a monocoque or stressed-skin structure. The strength of a
fuselage is very similar to nature's most perfect monocoque structure, the egg. Like the
egg, the fuselage can withstand tremendous loads when properly applied, but yet is
prone to localized failure when subjected to concentrated loads. The skin shape is
determined and maintained by web-like frames or bulkheads and also by longeron
angles and skin stiffener strips. The longerons and bulkheads also provide localized
strength for the attachment of wings, empennage, controls, canopy, etc. When the skins
are riveted in place, the fuselage becomes very rigid and self-supporting.
There are some variations in constructing the fuselage, depending on whether the
builder has chosen the RV-6 or RV-6A, and which canopy, sliding tilt-up, is to be
installed. BE SURE THAT THE INSTRUCTIONS
YOU ARE FOLLOWING APPLY TO THE AIRPLANE YOU ARE BUILDING.
JIGGING
The recommended jig for RV-6/6A fuselage construction is detailed on DWG 23. This jig
could be referred to as an "inverted bed" or "horizontal ladder" jig. It consists of two
longitudinal beams with perpendicular crossmembers and legs for supports. It is
cross-braced, so it is rigid in all planes. Since the top longerons are horizontal over most
of the fuselage length, they can be directly supported on the top of the jig, using a
horizontal level plane as a jigging reference. A firm centerline can be marked on the jig,
independent of the straightness of the main beam side-members. Since the fuselage has
a large opening for the canopy, and horizontal top longerons, it is logical that the
fuselage be jigged and constructed in the inverted position.
JIG CONSTRUCTION
The RV-6/6A fuselage jig shown on DWG 23 is relatively inexpensive and easy to
construct. Materials and tools available to certain builders may permit the fabrication
of a different, perhaps superior, jig, but the design shown is a good compromise of
simplicity, cost and quality.
Lumber used in jig construction should be as straight and dry as possible. Drying,
shrinking lumber may disturb alignment. Assembly of the jig with 8d and 16d nails is
sufficient: however, for maximum rigidity, the use of glued joints and lag or drywall
screws are recommended. If the jig is intended for use in the construction of several
fuselages, these added steps in jig construction will pay long term dividends. Leg
lengths should be uniform and can be nailed on irregularly if the shop floor contours
dictate. Shims can be used under the legs if necessary during final leveling. It is a good
idea to attach the legs to the shop floor. If your floor is concrete, a structural adhesive
like Liquid Nails works well.
Once the jig is leveled both longitudinally and laterally, establish a centerline with a
taut string or wire. As mentioned before, this centerline is independent of the
straightness or waviness of the edge beams. The horizontal crossmembers of the jig are
shown with beveled edges to permit maximum access to the structure while being
drilled and riveted. The position of these crossmembers should correspond to both the
dimensions listed on DWG 22 and DWG 23. However, individual aircraft vary slightly
and it is possible that bulkheads may need to be shifted slightly to support a smooth
skin, especially bulkheads F-607 and F-608.
Fasten the crossmembers that support these bulkheads with screws, so they can be
repositioned if necessary.
BUILDING THE BULKHEADS
Most RV-6/6A bulkheads and fuselage ribs are formed in two or more pieces and then
riveted together to form the complete bulkhead ring. The smaller bulkheads in the rear
of the fuselage are formed in one piece.
Fabrication and assembly of the bulkheads is detailed on DWG 23 through 23.
THE FIREWALL
The F-601 firewall bulkhead comes from the factory partially pre-drilled and clecoed
together. The remaining holes punched in the stainless steel panel must be continued
through the aluminum angle reinforcements and WD-602/603.
Determine the hole sizes and finish drill the reinforcing angles and weldments. Label
all parts so they can be easily relocated, then disassemble the firewall, deburr and
prepare all the parts for riveting. Take the time during disassembly to study the
firewall and learn how the components fit together -- having a good mental picture will
be a big help when it comes time to put all the parts back together. Prime the steel and
aluminum components before riveting -- the stainless, of course, needs no priming.
If you are building an RV-6A, you must fabricate and drill the F-6122 angle oh the left
side
For the RV-6, these holes may simply be filled with rivets or a thin strip of aluminum
may be riveted to the inside of the firewall.
The rectangular opening in the center of the firewall must be filled. Use the F-601K
recess if you are installing an engine with a prop governor or a spin-on oil filter (new
engines from Van's require the recess) or a flat sheet of stainless steel if your engine
does not require a recess.
When the parts are completely prepared, rivet the firewall together. Note the rivet
call-outs carefully. The RV-6/6A firewall uses flush rivets with the heads forward. The
resulting smooth surface on the engine side of the firewall makes cleaning and
mounting accessories much easier.
One of the objectives of the firewall is to keep fumes and liquids in the engine
compartment from entering the cabin. Some of the folded and bent corners have
unavoidable openings; around the lower corners of the firewall and the bends of the
firewall recess, for instance. These should be sealed with tank sealant or Hitemp RTV
(available in auto parts stores) during construction.
THE BULKHEADS
Bulkhead F-602 is constructed per DWG 22 and DWG 25, and there is no assembly
required prior to fitting into the fuselage framework.
F-603
Bulkhead F-603 (tip-up canopy) or F-6103 (sliding canopy) is the instrument panel.
Construction of the panel is best left until the fuselage is upright and off the jig.
F-604
The construction and assembly of wing attach bulkhead F-604 is covered in Section 7.
Now that you have the parts, there are a few other things that can be done before the
bulkhead is installed in the jig. The control stick assembly shown on DWG 41 may be
prepared and assembled, at least temporarily. Clamp the F-633 control column mounts
to F-604 and double-check their position by fitting the control stick assembly.
Mark and drill the F-663s for the bolts that will attach them to the bulkhead.
While the sticks are mounted, you may mark and cut the flange of F-604 to allow full
control movement, as shown on DWG 37.
A "spar substitute" spacer is needed in bulkhead F-604. This spacer serves several
purposes. First it maintains the position the side flanges relative to each other, so they
cannot be pinched together during assembly. Second, it helps keep the bulkhead flat.
The bulkhead should be as flat as possible when the floor ribs and bottom skins are
drilled to it. If it curves, it will be difficult to align the holes in the spars and get the bolt
through them.
Use a piece of lumber, or laminated plywood and/or lumber, equal to the spar in cross
section, damped or bolted to the forward face of F-604A. It should several inches wider
than the bulkhead, so it protrudes out each side of the fuselage, and as wide as the spar.
Make cutouts where the seat ribs join the bulkhead, so the ribs can be ciecoed on when
the time comes.
Another method of keeping the bulkhead straight is to install small wood spacers at the
outboard ends, to maintain the proper gap between F-604A and F-604B, then bolt the
W-620 splice plates against the fore and aft faces of F-604. Use temporary hardware
store bolts.
F-605
Bulkhead F-605 consists of many parts which must be accurately positioned, drilled,
and riveted together.
However, most components are straight sided, brake-formed parts that are easy to jig
and fit. The F-605B Center Section Bar has been formed to the specified curvature and
conforms to the F-605A Bottom Bulkhead. The two F-605C Bars should be cut to the
specified length and taper in preparation for assembly.
F-605 assembly begins by splicing together of the right and left halves of F-605A as
shown at the top center of DWG 26. The two parts are (aid flat side down on a flat
surface and the straight upper F-605 flanges are clamped to a straight angle or board.
Then the 0.032 splice plate is placed over the butt joint at the center (rear side of spar;
between the flanges), and drilled per DWG 26. Note that a hole will later be needed in
the center of this splice, so this should be marked and rivet holes spaced accordingly.
While ciecoed together, the F-605A is turned over face up so the F-605B and F-605C
bars can be positioned
and drilled. The F-605B bar should be centered on the bulkhead with its ends 1/8" up
from the bulkhead channel bottom. Use DWG 26 and DWG 33 to locate the seat ribs,
baggage ribs and seat belt anchors.
Carefully mark the rivet holes on the F-605B and F-605C. The locations may be
adjusted slightly to center in rib flanges. Clamp F-605A, B and C firmly together and
drill the rivet holes. The bars can be removed to make further assembly of the bulkhead
easier.
Layout of the major parts of the F-605 assembly should be done on a flat tabletop
covered with a sheet of thin plywood or particleboard which can be drilled.. At a glance,
the bulkhead appears square, but it is not. The bottom width is 1/2" less than the top
width. Recommended procedure is mark out the outline on the jigging surface, starting
with the flat top surface, along a straight edge of the particleboard sheet. Measure and
mark the ends and center of the top width. Then, using a carpenters square or
equivalent, draw a light line square (perpendicular) to this edge from each mark down
to the bottom of the bulkhead. Measure outward from the center to locate each of the
bottom corners. Cross check these points by measuring inward 1/4 inch from the light
square lines. Once the corner points are verified, draw in dark side lines. Now you can
overlay this pattern with parts F-605A and F-605F, front side down, followed by the
F-605D side channels. These four primary bulkhead members can be held in place with
clamps or nailing blocks.
The lower corner intersections of F-605A and F-605D can be marked and drilled,
placing several clecoes in
each intersection to further secure it to the jig. However, be careful not to drill any
holes in the area covered by the F-605B bar, Finish the F-605D side channels by using
the Unibit to drill the 5/8" rudder cable holes and cutting the openings for the manual
flap arms.
NOTE: DO NOT cut the flap arm holes if you are installing electric flaps.
While the Unibit is out, you can also drill the trim cable hole (manual trim only) and
the corners of the pushrod opening in F-605A.
If you are installing a sliding canopy, the side channel reinforcement parts F-605E, H,
and I can be omitted. If you are installing a tip-up canopy they can be positioned now.
Before drilling, check that they all fit together such that the top fuselage longeron, an
AA6-125 3/4 x 3/4 aluminum angle extrusion, will fit into the upper comer notch as
shown in detail "A". Note that the thickness of spacers F-605H and I in conjunction with
the flange of channel F-605D are approximately equal to the 1/8" thick longeron angle.
If additional spacers are needed for a snug fit of F-605E, they should be installed
in the inboard side of the channel.
Cut and position F-6Q5G. Be sure that it is snug up against the top of Channel F-605F
by clamping them together. Now, this corner assembly can be drilled and clecoed to the
jig. The side spacer strips can be held in place with tape, because they will eventually be
riveted in conjunction with the fuselage skin.
Disassemble the entire bulkhead, deburr the holes and edges, remove scratches, and
prepare for priming.
The bar and angle components are not Alclad material so must be primed. After
priming, reassemble and check for proper alignment. Then rivet the major components
together. Note that DWG 26 shows the location where seat and baggage ribs will later
be attached, and shows these holes with circles denoting that they are to be left open at
this time. Cover these with tape to avoid accidental riveting.
Before riveting on the F-605B & C bars, refer to DWG 33, section E-B which shows the
attachment of the F 634 Seat Belt Anchors to the forward face of this bulkhead assembly.
Clamp the anchors to the F-605 bulkhead temporarily and look for any interference
between them and the rivets that will join F-605 A &B.
AN3 bolts are used to attach the anchors to the bulkhead. The position of these bolts in
the flanges of the seat belt anchors may be adjusted slightly to maximize the distance
between bolt holes and rivet holes.
Machine counter sink F-605B&C and use AN426AD4-6 flush head rivets where the
flanges of the seat belt anchors cover the rivet holes. Pre-drill the anchor flanges for
AN3 bolts, then clamp the two anchor halves to the F-605 with a 1/8" spacer between
them and drill 3/16" holes through them and the bulkhead. Position the outboard
anchors. You will find that one of the existing rivet holes coincides with the bolt hole in
the anchor.
Enlarge this hole in the bulkhead to 3/16", (this rivet will be replaced with a bolt) then
complete the drilling of all the other anchors. The steel anchor parts can now be
removed, primed, and stored until they will be needed for final assembly. The remainder
of the bulkhead can now be riveted. Remember to leave holes used to attach seat and
baggage ribs.
F-606
Bulkhead F-606 consists of three primary segments which can be accurately jigged
simply by aligning the tooting holes with 3/16" bolts or 3/16" clecoes. However, because
of the possibility of free-play in the holes, the alignment can be checked by taking
accurate square measurements as shown in Fig. 3-1. Because of variations in
production, the F-606A bulkheads sometimes have a slight flange on their inner edge.
This should be trimmed off because the inner edge of the bulkhead web must be flat so
the baggage bulkhead can be installed later as shown in DWG 37. A fourth member,
F-606C, is riveted to F-606 as shown in DWG 33. The forward facing leg of the F-606C
angle will be used for attaching the baggage floor. Position this so it will be level with
the baggage floor, if you choose to install F-606C along with the initial assembly of this
bulkhead, you should check its position by fitting the baggage floor ribs in place on the
lower portion in the positions given on DWG 33. The option is to delay installing F-606C
until the basic fuselage assembly is underway, at which time it can be installed along
with the baggage ribs.
Join the top of the F-606 bulkhead halves with just a couple of clecoes. Fuselage and
canopy supports will be attached here later (for either canopy) and the final rivet type
and spacing will be determined then.
F-607 and F-608
Bulkheads F-607 and F-608 are two piece assemblies that are simply riveted together as
shown on DWG 27.
However, to determine the exact shape of the finished bulkhead, it is best to damp the
halves together for right now and install them in the jig. Later, as the skins are being
fitted, the bulkhead halves can be moved slightly in or out until they contact the skin.
Remember, the skin is what the air "sees" as is goes past the airplane. It is more
important to have a smooth skin without waves or wrinkles than to have the bulkheads
match the drawing perfectly. When the bulkhead/skin fit has been determined, then the
halves can be riveted together.
F-611/612
NOTE: Details of F-61 1 and F-612 differ for the RV-6 and RV-6A. In the RV-6A, the
F-611 is built by riveting the F-611 and F-611B bulkheads together with the F-611D
tapered bars. The F-612 is a single piece bulkhead installed with the flanges forward.
In the RV-6 they are double flanged bulkhead assemblies made by riveting two
otherwise identical bulkhead halves back-to-back as shown on DWG 28. Bulkhead F-61
1 also includes the two F-61 1C aluminum bars used to attach the stabilizer to the
fuselage (see DWG 34.) These should be cut, marked, drilled, and primed prior to
riveting together with the bulkhead halves. Do not drill the holes that must be drilled in
assembly with the Wd-609 tailspring mount or the horizontal stabilizer.
After riveting, the flanges of F-611 and F-612 should be bent approximately 98 ｰ and 82
ｰ. Adjust these angles to fit the skin as closely as possible. Small flutes can be formed in
the flanges to help straighten the webs so they mate better back-to-back. Similar flutes
can be used to straighten the remainder of the bulkheads, just as with the wing and
empennage ribs. However, you may wish to mark the rivet patterns on the bulkheads
before doing any fluting so the flutes can be located between rivet locations. Also, rudder
cable holes and holes for control push rods can be made at this time. The rudder cable
holes can be made easily and neatly using a UNIBIT.
NOTE: DO NOT notch the F-611C/D bars to fit the main longerons. The longerons will
be notched to fit around the bars. Small notches in F-61 1 C/D to accommodate the
J-stringers are acceptable.
All mating surfaces of bulkheads should be primed prior to riveting together. Even if the
builder chooses not to prime the entire interior of the airplane, it is suggested that
pieces of aluminum which come in direct contact with each other be primed. Moisture,
usually from condensation, can collect in the thin spaces of riveted joints, and remain
there much longer than on an exposed surface. Even though the aluminum is Alclad
protected, corrosion is more likely to occur in joints for this reason, and if it does, is
nearly impossible to treat.
FLOOR WEBS, SEAT RIBS, AND BAGGAGE RIBS
Fuselage side channels, seat ribs, and baggage ribs, shown on DWGs 29 and 30, will all
be used in the initial assembly of the fuselage skeleton. You may want to work in stages
such as attaching all bulkheads, longerons, and stringers to the jig before doing the
preparation work on the seat ribs, baggage ribs, etc.
Being able to temporarily fit these parts in position on the jigged assembly will help the
builder understand the reasons for the notches, bends, and tabs, which help the parts fit
together. Thus, the parts can be custom
fitted rather than just working to matching dimensions.
JIGGING THE BULKHEADS AND LONGERONS
The exact sequence of attaching bulkheads and longerons to the jig is somewhat
arbitrary, but the concept is simple. The job of the bulkheads, longerons and stringers is
to hold the skin in the proper position... one
experienced builder defined his approach to jigging the fuselage as "thinking from the
skin in and building from the center out." Shimming, moving bulkheads slightly, even
altering the bulkheads a bit, are all acceptable methods of assuring that the skin
presents a smooth uninterrupted surface to the airflow.
First, attach the F-601 firewall bulkhead to the upright 2x4's at the head of the jig. 3/4"
thick spacer blocks will be necessary to offset the firewall from the 2x4's enough that its
flanges will dear. Use 1/4" hardware store bolts to attach through 1/4" holes drilled
where 3/8" bolts will later attach the engine mount. Measure carefully to assure that
the firewall is level and vertical in the desired planes, and that it is at the correct
vertical elevation. Vertical alignment can be altered and/or stabilized by the addition of
diagonal braces from the top of the 2x4's to the side beams of the jig. Carefully align and
bolt the rearmost bulkhead F-612 to the end post of the jig.
Now the upper fuselage longerons can be bent and fastened to the jig. Bending can be
accomplished by clamping the angles in a vise (with protective jaw overlays to prevent
scratching) and applying pressure by hand to bend. There are two different bends to be
made in the RV-6/6A longerons. The first is a simple bend that causes the longeron to
incline downward toward the firewall (see DWG 22). The displacement needed
at the forward end of the longeron is shown on DWGs 22 and 23 and in Fig. 8-2, which
illustrates the bending procedure. We have shown both left and right side longerons
clamped together in the vise so they can both be bent at the same time and to the same
degree. The bend should be sharp rather than a gradual arc, and should not extend
more than 1 1/2 inches.
The second and more important bend is the gradual horizontal arc needed to contour
the fuselage side in the cockpit/baggage compartment area. Refer to top view DWG 33
for a general view of this curvature, and to
DWG 22, which includes a full scale layout of the contour. This contour should be traced
onto a sheet of metal or thin plywood to make a female template for checking of the
longeron bends. It will require a series of small arc bends to form the angle to a close
approximation of this shape and will no doubt require a "trial and error" approach.
We have found that often a double bend occurs even when a single bend is attempted.
By this we mean that the aluminum angle will twist as the bend is being made. We
recommend using a simple straightening handle as shown in Fig. 8-2. It is just a piece of
2x4 lumber about 1 ft. long with a slot 1/8" wide and 3/4" deep sawed into it. This block
fits over one leg of the longeron angle and acts like a seamer, through which a twisting
action can be applied to counteract the twisting due to bending of the longeron.
The vertical leg of the longeron angle should be parallel to the skin that will be attached
later. This may be visualized from the plans and the shape of the bulkheads. Forward of
F-604 the rounded shape of the upper fuselage requires the longerons twist inward. The
Wd-602/603 weldment arms are set at an angle to match the longeron. Generally, the
longerons aft of F-604 are "flat"; that is, the horizontal leg is truly horizontal and flat
against the jig crosspieces. This is especially important through the canopy area
between F-604 and F-605, but may be adjusted slightly aft of F-605 to match the
bulkheads and provide a smooth surface for the skins.
By damping both longerons together as before and holding both in a large vise as shown,
a downward pressure can be applied to cause a gentle bend near the vise. By releasing
the angles, moving them a few inches, and clamping with the vise again, a second bend
increment can be made. This procedure is continued, using the bending template to
check the curve as you progress. It should be possible to achieve a curve with a
maximum deviation of less than 1/8" using this technique. Again, remember to correct
for twist at each bend increment. A slight overbend is acceptable because a slight
straightening tends to occur while riveting on the side skins.
When your longerons are correctly bent, they can be placed on the jig and the jig and
clamped down with clamps like those shown in Fig. 8-3. Made from AA6-125x1x1 angle
(or any scrap angle on hand), these work well when tightened with a lag or drywall
screw.
The longeron will have to be shimmed at an angle to correspond with the curvature of
the bulkhead at the F-601 and F-602 stations. Initial fitting can be done with
approximate shims or with the clamp in a loose position. Minor bend corrections can be
made before proceeding.
Now additional bulkheads can be clamped in place, starting with F-604 and F-610.
Since neither of these bulkheads extend into the framework of the jig, extensions will
have to be added to the jig crossmembers per Fig. 8-4 to facilitate this attachment.
Before drilling and clecoing the bulkheads to the longerons, be very sure that they are
centered on the line previously drawn down the jig, are the correct height above the jig
rungs (or the longerons) as shown on DWG 23, and that they are vertical about the
centerline. This can be checked with a plum line or carpenters level as shown in Fig.
8-3.
NOTE: F-604 is NOT vertical. It forms a slight angle to the longerons so the wings will
be at the correct angle of incidence when they are attached. See the dimensions on DWG
22.
Bulkheads F-606, F-607, and F-609 can be clamped directly to the jig crossmember. In
addition to corresponding to the height dimensions listed, bulkheads F-606 through
F-612 should describe a straight line established by the bottoms (tops as jigged) of
bulkheads F-606 and F-612, Cross-checking this, the bulkhead tops from F-606 through
Fr609 should fail on a straight line.
Bulkhead F-611 presents a special problem, because the projecting F-61IB bars
interfere with the main longerons. Be sure to notch the longerons (see DWG 34), WOT
the F-61 1B bars.
At first, the bulkheads are rather difficult to position accurately because they are light,
flexible, and secured to the jig at only one point. Adding the seat rib, baggage ribs, and
other horizontal webs and stiffeners to the forward half of the fuselage, and the
J-section longeron/stiffeners to the aft fuselage adds considerable rigidity.
Because of the size and flexibility of bulkheads F-606 and F-607, additional stiffeners in
the form of the F-656 gussets are added as shown on DWG 32. These simple gussets are
fabricated by the builder and riveted to the bulkhead and top longeron to prevent the
bulkhead webs from twisting and thus losing their strength.
Starting at the firewall, the lower longeron angle segments can be cut and clamped in
position between F-601 and F-604. The angles can be clamped directly to the outside of
the Wd-603 weldment arms on their forward end and to F-604 using the F-654 and
F-655 gusset plates as shown on DWG 31. The gusset plates may be drilled and clecoed
or even riveted to F-604 at this time, but the longerons should not be drilled on both
ends until final positioning of F-604 is established and triple checked.
N0TE: RV-6A builders will replace the F-654/F-655 gussets with the large F-6101 gusset
shown on DWG 59.
Be sure not to drill for rivets in the areas shown on the lower longeron - bolts for the
gear leg mounts must be installed here and it is important that there is no interference.
Proceeding rearward, the seat ribs F-615 through F-619 can be prepared. At least one
F-619 rib must be split and altered as shown on DWG 33 so the control column can be
installed. Installing the control column and lower splice plate is easier if both F-619 ribs
are altered. The large hole in both F-618 and F-619 should be opened to the "shark-fin"
cutout shown in DWG 29, to allow for control movement.
Now these bulkheads are positioned between F-604 and F-605, drilled and clecoed in
place. Then, baggage ribs F-625, F-626, and F-627 are installed in the same mariner.
These ribs will automatically position bulkheads F-604, F-605, and F-606 relative to
each other. However, they should be carefully measured to assure that the dimensions
shown on DWG 22 are held. This is particularly true of the distance between F604 arid
F-605, which corresponds to the spacing between the main and rear wing spars. The
builder should carefully measure his wing spar spacing and then alter the
corresponding fuselage bulkhead dimensions if necessary. It is more important that the
wing and fuselage mate accurately than that these bulkhead locations be held.
NOTE: Optional external entry steps are available for both sides of the RV-6/6A through
Van's Accessories Catalog. The tailwheel airplane has little need of f step, unless the
occupants have some disability, but many RV-6A builders find them very useful. RV-6A
builders who are installing the optional external step kit should incorporate their
installation with that of the F-625 and F-626 ribs. It is much easier to. cut the required
holes out on the bench then when the ribs are riveted into a large assembly.
Side channels F-620 and F-622 can be fitted at this time to further align and stiffen the
forward fuselage.
Clamping these in approximate position stabilizes the framework enough that more
measurements can be made for final positioning.
When positioning the seat and baggage ribs, check to assure that they are aligned with
the bottom flanges of the bulkheads to which they are being attached. This can be done
in the same manner as suggested for the empennage and wing ribs, by using a strip
clamped on to simulate the skin.
Proceeding rearward, rib F-629 is installed between bulkheads F-606 and F-607. Before
installation, this rib must be completed, per DWG 30, by the addition of an AA6-063 x
3/4 x 3/4 angle along its upper edge. This
rib, along with a similar vertical web (F-628) to be installed later, provide the mounting
points for the elevator bellcrank mechanism.
Following this, the VA-1 17 J-channel stiffeners can be added to the bulkheads in the
rear fuselage. These should fit in the slots provided in the bulkhead webs. If not,
enlarge the bulkhead slot just enough to clear.
Place both the F-678 and the F-673 side skins in their approximate positions and be
sure that the overlap between them actually occurs on the J-Channel. Repositioning the
J-Channel slightly is acceptable.
Either of two procedures can be used when riveting bulkheads to longerons or stringers.
One is to position a rivet in the center of the intersection, and then later lay out the skin
rivet pattern so it misses this intersection, the other is to rivet the intersection together
with a "tack" rivet placed off-center as much as possible. Then the center of the
intersection remains available for the eventual skin rivet. The small NAS1097AD3 rivet
(you guessed it- see Van's Accessories Catalog) is perfect for tacking, but AN426AD3
flush head rivets may be used as well.
Notice that the center stringer in the fuselage sides extends forward of bulkhead F-607
and ties into F-622.
As the stringers are being installed, check the alignment of each bulkhead before the
stringer/bulkhead joint is drilled. The bulkheads are rather flexible and do not remain
straight on their own. As stringers are being installed, draw a string tight alongside
them and see that they are straight. The eventual straightness of the skin depends on
straight stringers. A slight fore and aft movement of the flexible bulkheads is
permissible to maintain the straightness of the stringers.
In addition to the bulkhead spacing given on the plans, bulkhead assemblies F-61 1 and
F-612 are positioned so the tail spring mount Wd-609 fits between them.
NOTE: In the RV-6A, the Wd-609 is not installed Instead, the Wd-627 Tie-down
Bracket will be installed after the vertical stab is mounted on the fuselage.
Bulkhead F-612 must always remain vertical, but F-61 1 can be inclined slightly if
necessary to fit up against Wd-609. The Wd-609 tail spring mount must be primed,
painted, and permanently installed before skinning of the fuselage begins. However, per
DWG 34, its final attachment to bulkhead F-612 cannot be completed until the vertical
stabilizer is installed. The mounting bolts connect through the vertical stabilizer spar,
bulkhead, and tail spring mount. The tail spring mount is positioned and bolted firmly
to F-61 1 and the bolt hole for pinning the tail spring in the mount is drilled before
skinning. When drilling this hole, check to assure that the axle end of the tail spring is
aligned vertically.
FUSELAGE SKINS
F-679
Skinning the fuselage begins at the aft end and works forward so the skin lap joints all
face aft. The first skin to be fitted will be the F-679 Tail Bottom Skin. This skin is 0.040"
thick because of the re-enforcement needed in the fuselage end for the tail spring mount
or tail tiedown. As a result, it is quite stiff and requires extra attention to obtain a good
fit. Re-bending the skin may be necessary. The forward end may be trimmed to match
the forward edge of the F-611 bulkhead. Once a good fit has been achieved, clamp it
down before it gets away and drill it.
F-678
Then you can move on to the F-678 Rear Bottom skin which extends from bulkheads
F-607 to F-610. This skin overlaps the forward end of the F-679 skin at bulkhead F-610.
If these lap joint holes have already been drilled through F-610 and F-679, they can be
back-drilled through skin F-678 also. The front end of this skin, as well as the sides, will
be lap jointed. Refer to DWG 36 for general skin placement details, rivet size and pacing,
and lap joint details. When initially drilling any skin which will be lap jointed, always
plan ahead by considering the final joint configuration. When drilling the skins, take
great care to avoid drilling into the notches on the bulkhead flanges. Many builders
prefer to pre-drill the bulkheads, then get inside the jig with a long drill bit and
backdrill the skin through the existing holes. It is an extra step but it is almost
foolproof.
F-673
The lower edge of this skin has a tapered bend that forms the bottom "corner" of the
fuselage. The aft end must be trimmed as shown on DWG 36 to fit over F-679. The
dimensions on DWG 36 are deliberately approximate: trim the skin so it fits your
fuselage. The more-or-less horizontal edge of the cut should provide edge distance for
rivets along the J-stringer - these are common with F-679. Plan carefully where F-673,
F 678, and F-679 all overlap so you do not drill interfering rivet holes
Plastic straps, similar to those used for wing leading edge construction, and duct tape
can be used to draw this skin down firmly over the lower corners of the bulkheads.
Start drilling in the center of the skin and progress both to the front and rear and
upward to the top longeron: We depart somewhat from normal procedure when drilling
the skin to the upper longeron. Normally, lap jointed skirts share all of the same holes
and rivets. In this instance, because of the considerable time lapse between removing
the fuselage from the jig and riveting the top skins, the upper edge of skin F-673 will be
drilled and riveted to the longeron while the fuselage is still on the jig. Only enough
rivets to hold the skin in position are needed at this time, (think of them as flush head,
non-removable clecos) so 3" rivet spacing is used. This spacing should be offset 1/2" so
the final 1" rivet pattern will interlace with it. The rivets on the 3" spacing will not be
visible when the top skin is installed.
Drilling should be continued down to the lower longeron and finally around to the lap
joint of the side and bottom skins, in this manner, any looseness in the skin will work
out to the edge and the skin will remain as taut as possible. If the fit between the bend
of the skin and the curve of the bulkhead is not perfect, small shims may be inserted to
prevent the skin from puckering when the rivets are set.
Once the F-673 is fitted and drilled, mark and cut the rear inspection openings that give
access to the elevator horns. Details of the doubler and cover are shown on DWG 46.
F-676/F-677
Next in sequence are the fuselage center bottom skins. Because of the curvature of the
fuselage bottom, this section was made in two pieces. Even by dividing the bottom skins
in two, they do not fit perfectly on the ribs and bulkheads. The compound curvature
required is very slight and the dose spacing of the seat and baggage ribs virtually
eliminates the effects of skin looseness and bulging associated with "forced" compound
curves.
The F-676 and F-677 skins extend several inches outward past the fuselage side. This
overhang is ultimately used to connect directly to the wing bottom skin and serve as a
structural wing root fairing. It is important that these skins be installed with overhang
per DWG 31. The skins are different widths so they form a lap joint 2 inches left of
fuselage center. This coincides with flange of seat rib F-619. See DWGs 31 and 36.
Once the skin is clamped in place, begin drilling in the approximate center and proceed
outward toward the ends and sides. Drill the final line of holes at the right/left side lap
joint that coincides with seat rib F-619.
F-672
Fitting the forward bottom skin F-672 comes next.
NOTE: RV-6A builders may fit and drift this skin, but should not rivet it to the airframe
until after the gear leg mounts are fitted. RV-6 builders may rivet this skin on.
F-672 is a one-piece skin, 0.040" thick, with tight radius flanges on both sides.
Positioning it on the fuselage is a straightforward process. It should nest close to the
shape of the bottom of the firewall and the forward lower longerons, almost holding
itself in place. It can be clamped to the forward facing flange of the firewall, flush with
the edge of that flange, or with a 5/8" extension past the firewall web. In other words,
the F-672 skin should extend 5/8" forward of the firewall web. It can also be clamped to
the longerons and pulled firmly into position. Begin drilling at the forward center on the
firewall and the rear center on bulkhead F-604. The F-672 skin should overlap the web
of bulkhead F-604 to permit a double rivet row lap joint. After the front and rear rivet
tines are drilled, the sides can be drilled into the lower longeron. Leave this skin clecoed
for the time being.
The AA6-063x3/4x3/4 floor stiffener angles should be cut and fitted to the forward
bottom fuselage between the firewall bulkhead F-60I and F-604. Refer to DWG 31 for
spacing and details for attaching these stiffeners to the firewall. The two center
stiffeners are riveted directly to the F-601J bracket on the firewall, and can easily be
drilled and clecoed on. The two outboard stiffeners are attached as shown in section
F-F¥ A small piece of angle ties the forward end to the lower angle of the firewall.
None of the aft ends of the four stiffener angles wilt ultimately attach directly to
bulkhead F-604. Eventually, brackets F-699 (see DWG 46) will support the ends of the
outboard stiffeners, but these cannot be installed until the wings are joined. You should
temporarily attach the stiffener angles to F-604 as shown in Fig. 8-5.
Drilling and clecoing the temporary angle segments as shown will hold the stiffeners
firmly in place for the remainder of the jigging procedure.
On ail the rivets attaching the stiffeners to F-672 and those attaching F-672 to the
F-601 and F-604 bulkheads the skin should be dimpled. It is tempting to machine
countersink the 0.040" skin, but this location
on the airframe is subject to a great deal of stress from the pulses of the exhaust and
propeller, as well as supporting the loads of entry and exit. The extra strength of a
dimpled joint will help protect against loose rivets later.
F-670
Next come the F-670 side skins.
The skins supplied with the kit are rectangular, so some trimming is necessary. Clamp
the skin to the top longeron, flush with the top of the longeron between bulkheads F-604
and F-605. Check to make sure that there is a 5/8" lap over forward of the firewall web
and clamp the skin there also. The skin is now located accurately enough so the cutout
for the rear spar stub can be marked and trimmed. Once this is done, the skin will lie
flush with all of the bulkheads. Now mark and trim the main spar cut out and the
aileron push rod hole. Also mark the edge for trimming back to rib F-624.
Between F-624 and F-606, a unique cone shaped bend must be made in the rear lower
edge of skin F-670 before this portion of the skin can be drilled. Trim the skin as shown
in Fig. 8-6, mark the bend line along rib F-623, and then clamp the skin to a table or
firm surface as shown in the photos. Hold the skin down along the edge of the desired
bend (position of ribs F-623), and carefully bend by applying pressure to the clamping
blocks on the free edge of the skin. Since the bend is only about 12", one person can
easily apply enough force to accomplish it. Bending is done gradually with a twisting
action on the "handles". The combined twisting and pulling action on the blocks should
be varied from the front to the rear of the bend so the bend radius will vary from about
1/8" at the forward end of the bend to about 3" at the rear edge of the skin bend.
The bending process can be interrupted at any time to re-fit the skin to the fuselage and
check the progress of the bend.
Rivet the F-670 skins beginning in the center and working forward and aft to the edges.
See DWG 37.
AN470AD rivets are used in the lower side areas which will be covered by the wing root
and root fairings.
Before riveting the skin to firewall bulkhead F-601 , refer to DWG 31 for details on the
installation of the piano hinge segments which are used for later attaching the engine
cowl. The hinge segments should be positioned as shown and along with the 0.032"
spacers, drilled through the already established holes in the skin. The 0.032 shim strips
are necessary to recess the hinge by an amount approximately equal to the thickness of
the fiberglass cowl that eventually butts up to it. The exact thickness of the fiberglass
varies, though, and we recommend leaving the hinges and shims clecoed until the cowl
is fitted. The shim thickness can be varied to provide an exact fit.
NOTE: RV-6A builders should only partially rivet the F-670 side skins, leaving the
lower 8-12" clecoed. All holes common to the F-670 side skins and F-672 bottom skin
must be left open for now. Remove the F-672 skin in preparation for fitting the main
gear leg mounts.
FITTING THE RV-6A LANDING GEAR MOUNTS
The Wd-626 Landing Gear Mount weldments are installed after all the fuselage skins
have been riveted on except for the F-672 Forward Bottom skin. The photos at the end
of this Section explain this needed access better than words can.
The first step is to install the wings in the fuselage. Ideally, the fuselage should be left
in its jig during the wing and landing gear installation. If workspace limitations or
other factors necessitate removal of the fuselage from the jig, it must be firmly
supported on saw horses so it can be leveled just as it was in the jig.
If ail has gone well, the wing spars will slip into the F-604 bulkhead and the
corresponding holes in the spar and bulkhead will align. (Refer to the instructions in
this Section on fitting the wing to the fuselage). Several bolts should be inserted
through the W-620 spar splice plates at the spar center, and several more AN3 bolts
inserted through the bulkhead and spar at more outboard points. Use enough to hold
the spars firmly in place relative to the fuselage. A padded C-clamp will hold the rear
spar in place.
Insert the landing gear legs into the landing gear mounts. Check the flat on the upper
end of the gear legs for a stamped letter "R" or "L" denoting which side to install the
gear leg in. Temporarily bolt the gear leg to the socket. Then, clamp each of the
mount/gear leg assemblies to the fuselage and wing spar in its approximate position. To
help hold the gear legs in position, use an 86" or longer piece of wide angle. The angle
can be either steel or aluminum, and ideally should be 1 1/2 to 2" on edge. An angle
made by nailing two 1x3 or 1x4 boards together can be used, if the lumber is straight
and true. Clamp this angle to the axle ends of the gear legs as shown in the photos.
Refer to DWG 59 for dimensions to check while positioning the gear legs. It is
important that the 21 3/4" height dimensions be maintained at the ends of the axles.
This height is measured from the very bottom of
the end of the axle, (NOT from the center) and is measured down to the surface of the
wing directly below. To reposition the gear leg ends, the clamps holding the gear leg
mount to the fuselage edge are left tight while the inboard clamp around the spar is
opened enough to permit movement. In this manner, the brackets can be shifted enough
to properly position the gear leg ends. The overall distance between the ends of the axles
should be approximately 86 inches. This distance may vary 1/2 inch or so because of
minor differences in the bend radii of the gear legs, etc. The vertical dimension is the
most important, and should be the same on both sides so the airplane will have level
stance on the ground.
Now, a 1/16" spacer is set behind the outer ends of the axles, as shown in Fig. 8-7. This
produces a little "toe- in" when the Wheels are installed, By using a plumb line or level,
a vertical line can be dropped from the outboard center of the axle down to the surface of
the wing. This distance should be 7 1/2 inches (plus or minus 1/4") aft of the forward
face of the wing spar. In addition, the angle between the axles and the upper leg of the
angle can be measured. This is the camber angle of the wheels, and should be between 7
and 8 degrees. The distance between the inner end of the axle and the angle flange has
been calculated to be 23/32" (0.718) for 7 ｰ and 13/16" (0.8125) for 8 ｰ. A measurement of
that space can be used to check the angle, in lieu of, or in addition to, a protractor
easurement of the angle. This requires an inside measurement, and may be checked by
cutting and trimming a spacer (made from scrap aluminum) which just fits the space,
and then measuring the width of the spacer. (See Fig. 8-7) Now the fun begins; Holes
must be drilled through the mounting plates of the gear leg mount, using the pre drilled
holes in the spar as drill guides. If a 3/16" drill were initially used, side loads
encountered while drilling could easily cause the holes in the aluminum spar to become
oversize. So, drill guide bushings should be used in the spar holes to permit accurate
pilot drilling of the holes in the steel mount. See Fig. 8-8. Any 3/16" outside diameter
drill guide bushing can be used, with a pilot drill of the same diameter as the bushing's
inside diameter. A total of 16 holes are needed in the spar contact flanges of each gear
mount weldment.
Twelve of these holes (refer to DWG 59) are to be 3/16" and are to be pilot drilled in this
manner. Four holes in each of the mounts must be enlarged to 1/4". These can be drilled
at this time. First, drill 3/16" from the rear, forward through the steel plates. Then, from
the front side (which is more accessible) enlarge the holes to 1/4" diameter.
While the mount is still clamped in place, use a 3/16" drill and enlarge the holes in the
steel mount. Once the pilot hole has been established, it provides a center to guide the
3/16" and minimize the chance of hole enlargement. After all of the spar/mount holes
have been drilled, drill the six 1/4" holes through the fuselage lower longeron into the
side points of the mount. As the first holes are drilled, temporary bolts and nuts should
be installed to prevent shifting as clamps are removed and the remaining holes are
drilled.
While the mounts are temporarily bolted in place, make cut out templates as shown
below in Fig. 8-9 for the holes where the gear leg sockets penetrate the F-672 Forward
Bottom skin. Make the templates of firm cardboard or aluminum. Make the cutouts as
accurate as possible for a close fit to the sockets. Then drill holes through the aft edge of
the template where it overlaps the rivet holes in lower flange of bulkhead F-604.
Now, these templates can be clecoed to the F-672 skin through its matching holes, and
the cutout pattern marked on it. Carefully cut these holes and then fit the F-672 skin on
the fuselage. The gaps around the socket exit holes should be kept as close as possible.
However, do not become upset if you find that the gap exceeds 1/8" in places. After the
final installation of the gear mount, the gaps can be sealed with RTV. This area is
usually covered by a gear leg/fuselage intersection fairing.
The landing gear mount installation work is basically finished at this point. The
mounts are removed from the fuselage and set aside, as are the wings. Continue with
the fuselage construction until the gear mounts are again referred to in the later stages
of airframe assembly.
REMOVING THE FUSELAGE FROM THE JIG
Once all the bottom skins have been riveted, the fuselage is sufficiently rigid to permit
removal from the jig. It can be turned upright and supported on saw-horses or any sort
of stands or cradles the builder may wish to use, at a convenient working height for
installation of internal parts and top skins. We found a height of about 45 inches at the
top longerons convenient. A main support should be located just aft of the firewall
because the fuselage bottom is flat at this point and it is also one of the strongest points
in the fuselage. Support directly under bulkhead F-604 is also possible, using either a
shallow "V shape cradle to match the fuselage shape, or a flat top support structure
with blocks to contact the fuselage at its edges.
Fit and drill the F-614 aft deck (DWG 28). Since the fuselage is not yet torsionally rigid,
the F-612 aft bulkhead should be clamped to a temporary support on the sawhorse (or
whatever) to hold it vertical. Check with a carpenter's level crosswise over the top
longerons at the cockpit and aft fuselage to insure there is no
twist in the fuselage. Bulkhead F-609 and deck F-614 should be fitted simultaneously
because they attach to each other as well as to the fuselage. The location of F-609, at
STA. 140 1/8 will establish the fore and aft location of F-614.
The F-614 deck must be prepared by cutting holes and notches that fit around the bars
extending upward from bulkhead F-611. Once in position, F-614 can be drilled per DWG
34 and 36.
The F-604E Bulkhead Cap is fabricated per DWG 28 and installed per DWG 31. It
connects the side webs of the bulkhead, forming a rigid box structure. Prepare the cap
for installation by center drilling a 1/4" hole that removes the radius of the bend, then
cutting the sides with a hacksaw or cutting disc.
Carefully smooth the edges of the hole to minimize the chance of cracking as the part is
bent the approximately 45 ｰ necessary to bend over the lower portion of the bulkhead
sides. Clamp in place and drill as shown. It can be left attached with clecoes until late in
the construction process, so it can be removed at any time for access to the inside of the
bulkhead sides.
Vertical Channel F-628 is fabricated per DWG 30 and installed per DWG 32 and 33. It
attaches with rivets to the bottom skin and to the rear face of bulkhead F-606 at both
the bottom and top, 1" to the right of center. This locates the bottom 2 inches to the right
of rib F-629. One of the primary functions of F-628, in addition to acting as a vertical
stiffener to the large F-606 bulkhead and providing an stiffener for the baggage
bulkhead, is as an anchor point for the F-635 Elevator Bellcrank. Section J-J' on DWG
33, section G-G1 on DWG 32, and DWG 40, shows this bellcrank, which is fabricated per
DWG 47. The center of the bellcrank is located by the intersection of the
AA6-063x3/4x3/4 angle flanges on channel F-628 and rib F-629. Position the bellcrank
with perfect vertical and lateral alignment, centered on the intersections of these angles,
and mark the hole position.
Drill a 1/4 inch hole through one side first, then through the spacers and bellcrank
bearing, and through the angle on the opposite side.
Upper engine mount reinforcement plate F-695 can be added at this time. Its
construction is shown on DWG 44 and is installed per DWG 31. Its purpose is to better
transfer engine and landing loads from the mount into the fuselage, and does this by
spreading the loads over a greater area than the steel Wd-602 mount alone can do. It is
attached with rivets. Because the top longeron is not quite horizontal, the F-695 gusset
plate needs a similar angle to interface with both this longeron and the horizontal top
crossmember of the firewall F-601.
Prior to skinning the upper rear of the fuselage, some preparatory work is needed.
First, bulkheads F-606 and F-607 heed to be reinforced by the addition of gusset plate
F-656 which is made (DWG 32) of remnant trimmings of 0.025 2024-T3 aluminum.
Drilling and riveting this gusset in place adds essential stiffness to the larger fuselage
bulkheads.
If you are installing the tip-up canopy, you may drill and install stiffener web F-687
and plate F-688 to the upper centers of bulkheads F-606 and F-607 per DWG 32 and
DWG 47. Together these serve as a reinforcement of the upper skin in the area where
the cabin frame brace will be attached. If you are installing the sliding canopy, it is best
to wait until the exact position of the canopy track C-662/C-663 is determined before
drilling these components. This wilt allow the use of common rivets and bolts.
Two J-section stiffeners are installed between bulkheads F-606 and F-608. After fitting,
drilling, clean-up, dimpling, and priming, the above components are riveted in.
Prior to further preparations for skinning, the F-636 Shoulder Harness Anchors
(shown on DWG 47) are fitted and drilled per DWG 33. Position the F-636 above the top
longeron, just forward of bulkhead F-608, and drill three holes for AN3 bolts. Do not bolt
the anchors in place at this time because they would interfere with riveting the skin.
Drilling prior to skinning is important because access is severely limited once the skin is
permanently in place.
CABIN FRAME
Fuselage construction details diverge in the cabin and instrument panel areas,
depending on the style of canopy chosen. Be sure that your construction from this point
forward is appropriate for installation.
If you are installing the tip-up canopy, now is the time to fabricate and install the
F-631 Cabin Frame and F 632 channel brace. The F-631 frame is a structural member,
with a "box" cross-section and a shape like a basket handle, it serves both as a mounting
framework for the rear windows and as a roll bar support in case of a nose-over ground
accident. It is meant to be a strong component and thus should be carefully constructed
and installed.
Construction details for the F-631 frame are shown on DWG 39. Carefully study the
cross section drawings and the photos and compare them with the kit component parts
before beginning construction. Working on a fiat table top surface, the right and left
halves of F-631 can be laid in position and their width and height dimensions checked.
As supplied with the kit these parts should be very close to design dimensions, but
minor trimming of the ends may be necessary. First check the width dimension at the
base. If your bulkhead F-605 dimensions are exactly per plans, the width to the outside
of the top longerons at that point should be 42 1/2 inches. Per the front view of the cabin
frame on DWG 39, the F-631A Channels should be 3/16" narrower per side, 3/8"
narrower overall, or 42 1/8" wide overall. If your fuselage width at the top longerons at
bulkhead F-605 is not 42 1/2", then the width of the F-631A channels must be changed
accordingly. When laying out these parts, the surfaces should be flat over the 3 inches at
the top intersection of the two halves.
Plate F-631E is used to join the halves together. Section B-B1 shows this detail plus the
rivet specifications and spacing. The front and rear halves of the F-631 assembly differ
in the type rivets used and in that the rear half includes riveting on additional angles
for attaching F-632 channel. These angles cap be positioned both by the dimension
given on the plans and by using the F-632 channel to determine the width dimensions
for the side angles. Cut the 1 1/2" diameter access holes in the rear half as shown on
DWG 39.
Once the front and rear halves of the F-631A frame have been drilled and clecoed
together, the two halves can be joined by the F-631B Straps. The straps are first
installed in the rear half of the F-631A frame by clamping it in place and drilling
progressively from the center outward to the ends. Cleco every hole as the drilling
progresses, and clean out the aluminum chips to assure that the strap rests firmly
against the underside of the channel flange. Then, with the strap clecoed into the rear
half, the front half is clamped on, drilled and clecoed on in the same manner.
Now, with F-631 assembly clecoed into a rigid unit, check the height (note that this
dimension is measured parallel to the F-631, not perpendicular to the longerons) and
trim the lower corners to meet the fuselage longerons at the specified angle. Use a
hacksaw and finish the cut with a file. The F-631C arid F-631D parts are then cut from
angle per DWG 39 and prepared for installation in the lower ends of the F-631 channel
assembly. Carefully study DWG 39 to understand the function of these angle segments
before drilling and installing them. Fit them in place on the fuselage along with the
F-631 channel assembly to assure that they will provide a firm base for attachment. In
particular, align the F-631C angle with the edge of the fuselage longeron. Drill and cleco
F-632C and D.
Trim the aft end of the F-632 Channel per DWG 39, and make angle F-632B and the
AA6-063 x 3/4 x 3/4 angle segments. Clamp the F-632 channel to the angles on the rear
face of F-631 to prepare it for fitting to the fuselage. Check the fit on both front and rear
ends of F-632, and alter if necessary.
All specified attach holes can be drilled and clecoed. This essentially completes the
Cabin Frame assembly, except for priming and riveting.
Since a major portion of the cabin frame is made of bare 6061-T6 aluminum, ail
components should be primed after disassembly and clean up. Included in the clean up
process will be the machine countersinking of all rivet holes in the flanges of the F-631
channels. Though AN and blind rivets respectively will be used in the front and rear
halves, both can be machine countersunk with a 100 ｰ cutter. CS4-4 blind rivets are
relatively soft and have heads that contour to the countersink. For final assembly, the
front and rear halves should be joined at the center with the F-631 E plates. Remember
to simultaneously rivet on the 0.063 angle segment that supports F-632 to the rear
F-631 channel. Then the F-631B straps are riveted to the front channel with AN rivets.
The F-631C & D angles can now be permanently attached to the channel. F-631D is
attached by two bolts per section A-Af, and F-631C is attached by three AN50910R10
screws and two #8 machine screws.
However, the machine screws are not installed at this time because they later attach the
fuselage skin to the channel assembly. The cabin frame assembly with the mount angles
in place can then be bolted to the fuselage via the reinforcement angle of bulkhead
F-605. Then the F-632 channel can be clecoed in place to connect.the cabin frame to
bulkhead Fr606. You will probably not want to rivet the F-632 channel in until later.
INSTALLATING THE TOP REAR FUSELAGE SKINS
The unsupported upper portions of the bulkheads lack stiffness, and often flex put of
position at repose.
They tend to lean forward or backward and can also twist so they are not perpendicular
to centerline. While the J-stringers and other webs and skin stiffeners help stabilize the
bulkheads, the entire upper section, stiffeners arid all, is flexible and can easily be
shifted fore and aft. It is a good idea to install some temporary braces to hold this
section in position as skinning is being accomplished. These can take almost any form,
but must not interfere with drilling the skins or bulkhead flanges.
If you have pro-drilled the bulkheads and are backdrilling the skins, the bulkheads
may be shifted slightly to achieve good contact, but be careful to maintain symmetry.
Careful seaming and shimming will also helps the skins fit without puckering around
the rivets, especially where the bulkheads meet the main longerons.
F-675
Rear top skin F-675 is placed in position on bulkheads F-607, F-608, and F-609. Since
the curvature of the top bulkheads is large, pre-forming the skin is not necessary. Use
straps or reinforced packaging tape to pull this skin down into position. The skin should
be checked to assure that it is centered, that it sufficiently overlaps the bulkheads at its
ends, and that the longitudinal edges both overlap the upper longerons by the
same amount.
Before any drilling is done, re-check the vertical alignment of the bulkheads. If this is
off, they can be shifted fore or aft into position before the skin edge is clamped (or taped)
to the fuselage side skin at the upper longeron. Mark and drill the holes per DWG 36.
Remember that there is already a row of rivets attaching the F-673 rear side skins to
the upper longerons. The rivet hole pattern drilled through F-675 where it overlaps
this longeron should take this into account. If the hidden row of rivets were uniformly
spaced at multiples of one inch, (such as 3" spacing) the specified 1" spacing of this rivet
line should automatically interlace without interfering with any of the existing hidden
rivets. Since the F-675 skin is only 0.025 thick it will need to be dimple countersunk.
The longerons/side skin build-up must be machine countersunk to accept the dimples,
acceptable in this case even though the side skin is only 0.025. The front edge of the
skin is not drilled to bulkhead F-607 at this time. It is preferable to drill this in
assembly with the F-674 skin.
F-674/F-6112
NOTE: The skin used here depends on the type of canopy. Check and be sure you are
using the correct skin.
If you are installing the sliding canopy, use skin F-61 12. Do not trim the skin as shown
for F-674 on DWG 36. Instead, wait until you have the sliding canopy frame and use it
as a guide to trim the forward edge of skin F- 6112. F-6112 may be fitted to the
bulkheads in the same way as F-673 and F-674. Those installing the tip-up canopy
should use F-674. Skin F-674 is one of the largest of the fuselage skins. It is an
important one because it is in a very visible area and interfaces with the rear portion of
the canopy. DWG 36 provides the dimensions for this skin and for the canopy cutout.
Mark this skin per the coordinates given for the cutout. Then cut out about 1" inside
this line to assure that enough skin is available to later overlap the Plexiglas canopy.
Excess skin can be trimmed after successful canopy fitting. Dimensions given for
trimming the rear edge of the skin are rough approximations, so do not trim this until
you have fitted it. A casual fit will permit an approximate trim. The ultimate shape is
determined after final fitting and drilling. Position the F-674 skin as you did the F-675,
using straps and tape to hold it down. Shift about as necessary, and then mark for
drilling. Start drilling at the top center of the skin, progressing uniformly toward the
bottom working alternately on right and left sides. If you are backdrilling, it is essential
to have a second person applying pressure to the outside of the skin near the drilling
point Make sure they use a thick wood block, so the drill doesn't find a finger...
Do both bulkheads F-606 and F-607 simultaneously. Upon reaching the bottom edge of
the skin, drill the longeron rivets between F-606 and F-607. All that remains now is the
forward fingers of skin that reach up to bulkhead F-605. Work forward from F-606,
pressing the skin down firmly to the longeron as you move forward to the narrow front
edge which can be taped or clamped down to hold its position and curvature while
being drilled. The main point to remember here is to avoid putting pressure on this
forward finger of skin which would force it up or down from its natural position. This
would cause the contoured inner edge of the skin to pull in or bulge out. This, obviously,
would be bad because of the good canopy fit we are expecting along that line. Drill the
holes through the skin and longeron from rear to front. Referring to DWG 39, two #8
machine screws are used to attach the front of this skin to the F-631 channel. Do not
drill these holes at this time. It may later be necessary to shim the entire cabin frame
upward. So, the skin to cabin frame holes will not be drilled until after the canopy is
fitted.
After drilling is complete, this skin can be removed for edge finishing and trimming,
hole debarring, and dimpling. Final sizing of the inside contour (canopy shape) will not
be done until after fitting and drilling of the canopy, and then will be done in place on
the airframe.
F-649/F-650 BAGGAGE FLOOR & SIDES:
The baggage side panels F-649 and F-650 are installed prior to the baggage floor. DWG
37 shows the installation of these two panels. Both must have flanges on their lower
edges, on which the baggage floor skin will rest. These flanges are marked and bent
during fitting. F-650 is riveted in to the fuselage structure,and F-649 is removable
through the use of anchor nuts and machine screws. F-650 is installed first, by locating
and drilling holes in side rib F-622 and bulkhead F-606. Then the forward side panel
F-649 is installed in the same manner.
We are now ready to install the baggage floor and the seat bottom skins. Begin with the
baggage floor skin F-647 R & L When cutting the skins per DWG 37, you might leave
them oversize in width by 1/8 to 1/4 inch, and then trim to fit as you install them, or use
stiff paper to make exact patterns that fit your airplane. F-647 R & L. are intended to be
flush with the inner edge of baggage ribs F-627, so the outer edge would be trimmed to
fit up against the baggage side skins F-649 and F-650. The rear of the skin should lie on
the F-606C angle, which is part of the F-606 bulkhead, and the forward end overlaps the
inner flange of bulkhead F-605.
Before you drill holes and cleco the floor skin in place, study the drawings for your flap
installation (manual or electric) and note the position of the actuator bearing blocks.
Also note the position of the F-685 Backrest Brace (DWG 38). These parts mount to the
baggage floor and the floor rivet layout should be adjusted to avoid any interference.
If you do not have a "hole finder" tool, you should not drill the holes through the inner
edge of the skin into rib F-627 until after the F-628 center plate is in place so the holes
through all three thickness are drilled in common. The F-647 floor skins are to be
permanently riveted in while the F-648 center plate is to be removable. (An optional
method is to drill and rivet the floor skin to rib F-627 with AN426AD3-3.5 rivets spaced
at 2" intervals, and then drill for the K-1000-08 anchor nuts at the specified 4" intervals
spaced between the rivets.) Drilling of the rivet holes through the forward end of the
F-647 skins and through bulkhead F-605 should also be treated in the same manner
because the F-642 seat skins will be fitted over them. No holes are drilled in the rear
edge of the skins at this time because these holes, for machine screws, will be drilled
later in conjunction with the F-651 baggage bulkhead. The F-648 center plate can be
positioned, marked, and drilled at this time. Installation of the anchor nuts should wait
until after the floor skins have been riveted in.
F-642 SEAT BOTTOM SKINS
The F-642 seat bottom skins are fitted next. Measure the exact locations of the F-634
Seat Belt Anchors and mark the seat skins to be cut out to that actual dimension,
should it differ from those shown on DWG 37. The outer edge of the skins are to be cut
to conform with the juncture of seat rib F-615 and the side skin, and the inner edge to
conform with the edge of seat rib F-619. The two bend angles in the skin conform to
those of the seat ribs. Like the baggage floor skins, these seat skins are to be
permanently installed with blind rivets, but the F-641 center plate is removable,
installation of the center plate should be delayed to coincide with installation of the flap
handle assembly. DWG 42 shows the F-658 flap anchor assembly mounted over the
center plate, the bolt and platenut which hold this assembly should be figured into the
screw pattern for the center plate.
When the F-642 skins are in, the F-639 and F-640 forward seat skins should be
installed. These skins are structural members, 0.040" thick, and provide fore and aft
bracing for the spar center section, so no parts or fasteners should be altered or omitted
in this area.
DWG 37 shows a cut out in F-639 and F-640 for the control stick. This cut-out can be
done after fitting and drilling so its exact location can be verified relative to the seat ribs
and spar. Ideally, the cut-out should be left undersize until the entire aileron control
system is installed, and then trimmed to the minimum opening size which will permit
full stick travel. The F-640 left seat skin is installed first, followed by the F-639 right
skin which overlaps it at rib F-619.
The exact sequence for drilling, disassembly, clean-up, priming, and final riveting of
the baggage and seat floor skins and sides is optional. Each part can be completed
individually or the entire section can be done at once, depending on the working habits
of the builder.
F-651/F-652 BAGGAGE REAR BULKHEAD
The baggage bulkhead parts F-651 and F-652 can be installed at any time, before or
after the baggage floor and side skins. The F-651 panel is installed first. It has been
sized to fit between the side panels, so should not require any trimming. It is attached
to bulkhead F-606 with machine screws and platenuts. Initial drilling with a #30 drill
will permit temporary holding with 1/8" clecoes. The screws through its bottom flange
into the flange on bulkhead F-606 are positioned as shown in the top view of DWG 37.
Both F-651 and F-652 must be modified to allow the shoulder harness cable to pass
through to its attachment in the rear fuselage. This is shown on Detail A, DWG 37.
Small strips of UHMW plastic are riveted on to protect the bulkhead from the stainless
steel cable.
The F-652 upper panel requires trimming to a contour approximately 1/2" inside the
bulkhead flange, and also requires shoulder harness cutouts. These cutouts can be done
after fitting and drilling to assure correct positioning. Note that there is a drawing of
the cutout reinforcement at the upper left hand corner of DWG 37.
After riveting the reinforcement plate on, its inner edges should be filed and sanded as
smooth as possible to minimize chaffing of the shoulder harness.
After fitting and drilling, the K-1000-08 platenuts can be installed. The baggage
bulkhead is a structural member. In addition to providing a barrier to objects in the
baggage compartment, it provides stiffness to the web of bulkhead F-606, and the
airplane should never be flown unless the baggage bulkheads are installed with all
screws in place.
FORWARD FUSELAGE
NOTE: Details of upper fuselage construction differ in the cabin area forward to the
firewall depending on the type of canopy chosen. Be sure you are working from the
correct drawings with the correct parts!
The exact shape and installation details of the instrument panel depend on the type of
canopy being installed.
The tip-up canopy permits access to the rear of the panel and some of the shorter
instruments after the canopy is installed. The fixed windshield and glareshield of the
slider does not.
Details of the sliding canopy instrument panel are shown on DWGs SC-1 , SC-2, SC-3
and SC-4.
Tip-up Instrument panel and sub-panel installation is shown on DWG 31. They both
require pre-assembly before installation onto the fuselage. The F-668 Sub-Panel need
only be riveted together as shown on the top half of DWG 35. The tooling holes can be
used for alignment, but should be crosschecked by the dimensions given. Also, a straight
edge should be used along the bottom flange to maintain straightness.
The top and bottom flanges need to be trimmed off at the center where they would
otherwise overlap.
The F-603 instrument panel needs considerable work before installation. The top
contour must be cut and the notches in the sides need to be marked and cut out. When
cutting the end notches, do not cut full depth until you fit it to the fuselage. To achieve a
more perfect fit, allow 1/16 to 1/8" of depth to be trimmed at assembly. When the panel
is trimmed to its final shape, (which may be later, after you've had chance to trim
the contour to an exact fit) the top flange material, AA6-063x3/4x3/4 angle, is cut to
length and notched at the approximate points shown. Lay the instrument panel on a
table and position and drill the angle at the center.
Cleco the flange to the instrument panel and progress outward with the drilling. Be
sure that the angle is perfectly aligned with the top contour of the instrument panel at
every drill point. After completing this, add the angle segments to the instrument panel
sides as well. The short horizontal pieces of angle can be left off at this time and then
positioned at assembly on the fuselage.
To assemble on the fuselage, the F-668 sub-panel is positioned on the upper longeron
17" aft of the firewall. It is also located by the F-646 Forward Fuselage Top ribs. Drilling
and clecoing quickly fixes these parts in place. However, the sub panel connects to the
F-621 Canopy Deck which must now be installed before proceeding with the instrument
panel installation.
If you are installing the sliding canopy, Canopy Decks F-6110 and F-6113 (DWG SC-1,
SC-2) are fitted instead.
The two halves of bulkhead F-6105 are fitted to the fuselage and clamped in the center.
Then longitudinal ribs F-6107 and F-6108 are fitted. (F-6108 is reinforced by the
addition of F-6109 so there is extra strength where the Wd-643 Roll Bar Brace is bolted
on.)
The intersections of these ribs and bulkheads may be adjusted slightly to achieve a
smooth surface for the F- 61 06 skin that will cover them. When everything fits properly,
the two halves of F-6105 can be drilled, and the angles holding F-6105 to the F-61 10
canopy deck fitted and drilled.
Now the top contour of the F-6103 instrument panel is determined. Clamp the
un-trimmed panel in place.
Use a level or a rigid straightedge, resting on top of the firewall and the F-6105, to
project the skin line onto the back of the panel. This assures a good fit when the skin is
installed.
The instrument panel itself may be installed in more than one way. As shown on DWG
SC-2, a flange of AA6-063 x 3/4 x 3/4 angle is fitted to the upper edge. This may be
riveted to both the panel, and later, to the F-6106 skin. The panel would then be
permanently installed, if the builder chooses, the flange may be riveted to the skin and
the panel attached with screws and nutplates, allowing the panel to be removed.
Remember, the fixed windshield and forward skin used in the sliding canopy
installation prevents any access from the top of the panel.
A full one-piece panel, even if attached with screws, is an unwieldy thing to remove once
it is full of instruments and radios. Some builders have devised segmented panels that
may be removed in several pieces, allowing much easier access to connections at the
rear of instruments and avionics. Since the exact details of such an installation depend
largely on the arrangement of the items in the panel, details will have to be worked out
by the builder.
CANOPY DECK
Canopy deck installation details differ with the type of canopy. If you are installing the
sliding canopy, use parts F-6110 and F-6113, shown on DWG SC-2.
If you are installing the tip-up, use the F-621A and F-621B canopy decks channels,
shown on DWG 30 and 32. The F-621B is installed first, and per the fabrication DWG 30,
is notched out at both ends. The aft end has its inner flange notched as required to fit
over plate F-657, so the length of the notch should be determined by measuring and
fitting. Also, a notch approximately 1 1/2" long must be cut from the inside flange of this
deck channel where it laps over the F-604 bulkhead cap. (Note F-604E bulkhead cap is
to be in place, either clecoed or riveted, at the time of this fitting). Once these notches
are cut, it can be positioned for drilling. As supplied, it has a straight edge, which is to
be marked and trimmed to the longeron contour.
When positioning this part, be sure that it overlaps the longeron at all points so, after
drilling, it can be trimmed to be flush. With the F-621B deck plate clecoed in place, the
F-621A forward deck plate is fitted. Its forward edge is to be flush with the F-668
sub-panel bulkhead, or perpendicular to the fuselage centerline. Its straight outer edge
should align with the top longeron, which is straight through this section. However, this
edge can be trimmed if required to match the width of the F-621B at their juncture. The
F-621A and F-621B deck plates are basically butt joined at bulkhead F-604. As supplied,
the F-621 B plate has sufficient length to lap under F-621A by about 1 inch. During
initial fitting, the parts can be lapped in this manner to determine and mark the trim
lines needed for a close butt joint. In their final condition, the only overlap of these parts
will be the vertical edge where the tab of F-621B (DWG 30) extends under the edge of
F-621A and is riveted to it.
DWGs 32 and 33 show an angle being used to join the deck with the sub-panel bulkhead.
Since these parts do not meet at exactly 90 ｰ, the short angle segment should be bent as
needed. F-668 is designed to be perpendicular to the top skin at its center. The F-646
webs are manufactured with a 90 ｰ angle to help hold F668 at this angle, The F-645
webs are drilled and attached with clecoes to the F-668 sub panel as shown on DWG 31.
Then the F-603 instrument panel can be fitted in place (final trimming of the end
notches and top contour) and temporarily clamped to both the fuselage cabin deck and
to the F-645 webs. Positioning should be checked, both for horizontal centering and for
vertical positioning. The vertical position can be between 1/4" and 3/8" below a line
projected from the firewall over the F-668 sub-panel. The horizontal angle segments
which attach the instrument panel to the deck can now be drilled. Section F-F on DWG
32 shows this detail, and shows the angle riveted to the canopy deck and attached to the
instrument panel with machine screws and platenuts. The instrument panel is attached
to the F-645 webs with machine screws and platenuts also, making it removable for
service.
CENTER CONSOLE & BASE
The F-682 Center Console and F-683 Fuel Valve Base can now be fabricated and
installed. DWG 47 shows the fabrication details for the parts, and DWG 32 shows the
installation, both in the side view drawing and in Section E-E' DWG 49 also shows these
parts as they are used for supporting engine controls and other system components. The
F-683 base unit should first be installed. It attaches to the wing spar center section
plates as shown in Section E-E¥ which cannot be finalized at this stage of construction
because the spar is not in place. It also attaches to the F-639 and F-640 forward seat
skins with machine screws and plate nuts where these skins overlap at the fuselage
center. For initial installation, the F-683 assembly can be clamped to the seat skins and
can be bolted to the F-604 bulkhead center by using spacer blocks to simulate the
spar/splice plate thickness, and undersize (3/16 - 1/4") hardware store bolts. Full size
holes can be made when the wing is being fitted to the fuselage.
Once the F-683 assembly is in place, the F-682 center console can be trimmed and fitted.
Its lower end attaches to the tab on the front of F-683 with machine screws and plate
nuts, and the upper end attaches to the instrument panel in a similar manner. Section
F-F shows how bracket F-685A is riveted to the instrument panel to provide a tab which
the center control console is attached to with screws.
Constructed in this manner, both the center console and the base unit are removable, as
is the instrument panel itself. This makes final assembly of the airplane easier and also
permits easier servicing and repair.
We expect that some builders may want to install a wider center console to
accommodate more controls, whistles, and buttons. We recommend against such a
modification because it would restrict the space available for the occupant's legs and
restrict the requirements for full aileron control movement of the stick.
We designed the center console as narrow as possible for this reason. The builder
cannot possibly appreciate, until the airplane is finished and occupied, the importance
of maintaining all available space.
SEAT BACK CONSTRUCTION & INSTALLATION
Drawing 38 shows the seat back construction. Assembly of the F-637 seat back is quite
easy. The F-637A seat back skin is completely pre-formed, although stiffening ridges
may not match the plans exactly. The result is that the overall length of the skin can
vary because of an "accordion" or "bellows" effect of the folds in the skin. It is not
necessary that these ridges be an exact distance apart; only that they do not interfere
with the F-605F bulkhead crossmember or the bottom of the seat.
Cut the side angles and clamp them to the skin flush with the upper edge. Drill two
#30 holes between each fold of the skin, starting at the top and progressing downward.
Again, the exact spacing of the rivets is not critical, and may have to be varied slightly
from that shown. The seat back skin was supplied intentionally overlength because of
the variations mentioned above. After drilling the side angles there will probably be an
excess skin overhanging at the bottom of the seat back. This can then be marked for
trimming, and the AA6 063x3/4 x 3/4 crossmembers can be added to the back side of the
bottom and top of the seat. The upper crossmember should be positioned in contact with
the underside of the top flange of the seat skin. This will require that the sharp corner
of the angle be rounded off so it will nest in place.
The lower crossmember angle should be drilled so the rivet holes will be common to
both it and the piano hinge half which attaches the seat back to the cabin floor. Per the
drawing, the piano hinge extends 1/4" below the bottom of the seat, requiring that the
rivet row be below center on the lower crossmember. Thus, the lower crossmember and
piano hinge should either be drilled at the same time, or the rivet holes should be
positioned low enough that they will center on the piano hinge for later back-drilling.
The upper center of DWG 38 shows the means of attaching the seat back to the seat
floor; via piano hinge segments. Pinning the seat back into these fixed position hinges
offers three different seat position adjustments.
The F-638 Seat Back Brace shown in the upper right of the drawing provides the other
positioning feature of the seat back. It also provides 3 positions corresponding to the
three base positions. The angles, shims, and plates used on F-605F can be fitted, drilled,
and rivet on either during the initial construction of bulkhead F 605, or after it has been
installed in the fuselage. These provide "slip in" notches for the seat back brace.
Before final attachment of the seat back brace to the seat back, clamp it in place and fit
the seat in its various positions. The seat back is intended to remain at the same
inclination, which means that the seat back and the seat back brace should always be in
the same respective positions. From this fitting, you can determine the location for
attaching the hinged seat back brace which will permit the seat back to fit easily in all
three positions. Ideally, the piano hinge segments at the seat bottom should be riveted
to the seat skin before the skin is riveted permanently in, so AN470AD4-5 rivets can be
used. If the seat skins are firmly in place at the time of seat installation, LP4-3 blind
rivets may be used.
CONTROL FABRICATION AND INSTALLATION
NOTE: The RV-6/6A can be built with either the standard manual flap control or the
optional electric. Details of actuator, actuator bearing blocks, and other parts differ, so
before you begin installing parts, be sure you have studied the appropriate drawings
and have a clear idea where things go.
Manual Flap Control
The flap handle and actuator, shown on DWG 42, are installed as shown on DWG #40.
Install flap control weldment Wd-613 by positioning it with mounting blocks F-680 and
F-661 in line with holes drilled through the side webs of bulkhead F-605. A third
mounting block, F-680, supports the flap mechanism cross-tube at a point just left of
center as shown in DWG 40. This two piece split bearing block is bolted to the flange of
the baggage compartment and seat ribs, and is installed after the center seat plates are
screwed down. Thus, K 1000-3 anchor nuts must be riveted to the bottom of the seat rib
flange for securing the bearing block bolts.
The flap lock/release mechanism consists of the F-658 anchor assembly and the F-660
Flap Release assembly, and is to be fabricated by the builder per the details in the lower
right of the DWG 42. The exact length of F-660 is to be determined at installation.
During fabrication, the F-658A flap anchor should initially be drilled to the mounting
base with only one hole, and held with a cleco fastener. Then it is positioned alongside
the flap weldment so the weldment can be marked for cutting out a slot for the anchor.
Unless you are one of the fortunate few with a milling machine in your shop, cut the slot
by drilling a line of holes with a #30 drill and then opening the slot with thin file. When
drilling, hold the flap handle perfectly flat on the drill press table so the holes (slot) in
the upper and lower side of the tube (handle) are perfectly in line. Through later fitting,
you can enlarge the slot enough that there is minimal interference with the curved arm.
Once the slot is large enough to accept the anchor bracket, clamp it in place and move
the flap handle through its complete travel range. From this you can determine where
to position the anchor assembly and at what angle relative to the base the anchor arm
should be. This is the reason for drilling only one hole initially.
The anchor can now be drilled to the seat ribs in its final position. The F-658D plug and
the VA-114 spring can be inserted into the flap handle and the F-660 flap release,
complete with the exception of final length trimming and installation of knob VA-110,
can be installed. Now the spring loaded flap latch mechanism is working and you can
measure the tube for cutting so the VA-IIO knob, when the F-660 latch assembly is in
the latched position in one of the anchor slots, will be just contacting its inner ridge in
the handle (as shown lower left of DWG 42.) installation of the flap mechanism cannot
be completed until the wings and flaps are fitted to the fuselage.
Determining the exact length of push rod links F-659 cannot be accomplished until that
time, and the cutouts in the fuselage skins cannot be done until then. These holes
should be kept to a minimum size, so it is necessary to have all parts in position so the
link can be connected and the flap exercised so movement of the connecting link can be
observed and allowed for. The length of these links should be should be such that with
the handle in the down position (near floor) and the flaps in the up or neutral position,
rod end adjustment both ways is still available.
Control Column & Sticks
These are fabricated in accordance with DWG 41 and installed per DWG 40. Final
installation of the Control column cannot be done until the wing is permanently in place.
However, it can be fitted temporarily for the purpose of determining clearances and
fabrication of control push rods. The control column must be inserted into the fuselage
without the control sticks installed. The openings in the seat ribs are large enough for
the control column ends, but not with control sticks installed. The F-633 Control
Column Mounts are supplied with the kit and conform to the drawings in the upper left
of DWG 47. They attach to the rear face of bulkhead F-604 with two of the 3/16" spar
bolts at STA 7.625 (7th hole from center). As indicated on DWG 47, the 3/16" holes in the
attach bracket are drilled in assembly with the bulkhead, or at least marked for drilling
by positioning it against the bulkhead. The mounting ears on the control column have
an inside dimension of 1/2" whereas the F-633 mount bearing is only 1/4" wide. The
remaining space should be filled with two AN960-10 washers on each side of the bearing.
If necessary for positioning the bracket, the bearing can be off center between the
mounting ears with an uneven number of washers per side.
With the control column in place, the control sticks can be installed and the push rod
and bearings can be installed. Adjust the bearing travel so the control sticks are parallel
in the neutral position perpendicular to the control column. When the wings are
installed, the W-618 push rod assemblies can be fitted, trimmed to final length, riveted,
arid installed, when positioning the ailerons in neutral and the push rods in neutral
position, check the position of aileron bellcrank F-617 on DWG 19 and adjust the push
rod F-616 if necessary to achieve this neutral position. Remember that the push rod
tubes are a non-Alclad aluminum and must be primed inside and out. Inside priming is
easily accomplished by closing one end of the tube with masking tape and then pouring
a small quantity of primmer in the other end. Incline the tube so the primer runs slowly
from end to end. Rotate the tube while the primer is running. Repeat this several times
to assure that ail surfaces have been coated and allow excess primer to run but the open
end.
The elevator push rods F-689 and F-690 must be fabricated and fitted. F-690 is a large
diameter tube, and special VA-101 ends are necessary. The blunt shape of these ends
will cause interference with the bellcranks if rod end adjustment is too short. F-690 has
been designed so the rod end bearing on the aft (elevator) end is installed with nearly
maximum length adjustment, and the long shank rod end used on the forward end
allows the necessary adjustment range. Note that these VA-101 end fittings are bare
aluminum and must be primed just like the tube. The forward end of the large diameter
F-690 is finished as shown on DWG 34, but the aft end will be cut to final length and
completed during when the empennage is installed on the fuselage.
The F-689 push rod assembly which connects the control column to the bellcrank can be
completed now.
The length is determined by setting the control stick in the neutral position (this not
necessarily vertical. The control stick slopes forward 0 ｰ-5 ｰ in neutral position) and
setting the bellcrank vertical. Remember to cut the tube long enough, so when rod end
bearings are installed, more than half the threads are engaged on each end. (Later/the
length of the F-689 push rod can be checked by putting the elevator in the full up
position and the control column in the stick-back position with its bottom arm only 1/8"
from contacting bulkhead F604. in other words, we want the stick to be as far back as
possible without interference when the elevator is in the "full up" condition. The overall
length of the pushrod can be adjusted with the rod end bearings as long as more than
half the threads on each bearing remain engaged.)
Getting the F-689 into the fuselage is a little difficult - but it is possible. Remove the
rod end bearings and slide the pushrod through the bulkheads from the rear. You can
exert enough force to flex the pushrod slightly if you are careful. If it just won't fit, the
holes in the bulkheads must be enlarged just enough (with a die grinder or file) to allow
it to pass through. Once installed, check for any possible interference.
Rudder & Brake Controls
Rudder and brake pedals are fabricated and installed per DWG 43a. Make the F-6117
brake pedals, but leave the F-6117A side plates clamped to the pedal for the moment.
Bolt the pedals and brake master cylinders in place on the WD-655 rudder pedals. It
will be necessary to use extra washers on the bolts at the bottom of the master cylinders
to space them from the brake pedals and avoid interference during operation.
The exact position of the F-6117A side plate will determine the angle of the brake pedal.
Bolt the master cylinders to the side plates, then loosen the clamps slightly, and adjust
the position of the side plates, until the brake pedals rest in the same plane. Tighten the
clamps to hold this position and drill.
The bushing blocks for the brake pedal weldment will require some additional work
before installing.
The F-61 16 and F-61 15 bushing blocks need to be drilled for all of the specified bolt
holes. When drilling, use a drill press and drill press vise (if available) to assure that the
holes are perpendicular to the bushing surface. The F-61 15 bushing block must also be
sawed in half to fit around the rudder pedal torque tubes.
When the blocks are reassembled, use a washer or two between them to replace the
material removed by the saw.
Slip the finished rudder and brake pedal assembly and F-6116 end bushing blocks in
position and clamp them on the fuselage longerons. Also, clamp the F-6115 bushing
blocks and F-6118 rudder pedal brace in place. Determine any repositioning of the
blocks which may be necessary for alignment or freedom of operation of the pedal
assemblies. Check carefully for any possible interference that could result in loss of
rudder or brake control. Now the holes can be drilled for the bolts attaching the blocks
to the angles.
The brake fluid reservoir is mounted to the top of the firewall on the engine side. Brake
lines, furnished with the finishing kit, are installed as shown on DWGS 40 and 49.
Brake line data and routing are covered in Section 10. Standard configuration calls for a
single set of brakes on the left side of the cabin. An optional dual brake kit, available
through Van's Accessories Catalog, can be installed on the right side also. This kit has
been designed for easy retro-fitting, and may be installed at any time.
EMPENNAGE/FUSELA GE ATTACHMENT
The horizontal stabilizer is the first of the empennage components to be attached to
the fuselage. Position the horizontal stab on the fuselage, and clamp it loosely to
bulkhead F-611 as shown in DWG 34, section B-B’ First, square the stab with the
fuselage, keeping the rear spar perpendicular to the fuselage centerline.
One means of checking this is to measure from each stab tip to a common point on the
forward fuselage centerline (Fig. 8-10.). When the measurements are equal, the stab is
square.
Level the stab with the top longerons so it is set at a zero incidence angle to the
fuselage, i.e., its centerline should parallel the fuselage top longerons. This can be
measured several ways as shown in Fig. 8-1 1. Since it is difficult to measure from the
centerline of the stab, a displaced centerline can be established by using blocks set on
top of the spars. The distance up from the longerons to the center of both spars can also
be measured. Check both ways to assure accuracy.
Drill the bolt attach holes through the HS-614 center angle on the forward stab spar
into the longeron and re enforcement angle on bulkhead F-610.
Now the vertical stabilizer can be attached. Position vertically as shown on DWG 34.
Align vertically with a carpenter's level or by checking tip-to-tip distances from the
horizontal stabilizer as shown in Fig. 8-12.
Center in fuselage at the same time. Then drill all attach holes through the angle
above the longerons at F-612, and through bulkhead F-612 and into the tail spring
mounts. Particularly when drilling the lower holes, measure very accurately to assure
that the holes are drilled into the correct position in the tail spring mount.
RV-6A builders should install the Wd-627 Tie Down Bracket (see DWGs 28, 34 and Fig.
8-16) on the aft side of the VS-603 spar. Two ANA bolts are used to attach this bracket to
the spar and the F-612 bulkhead.
Once the VS-603 rear spar has been drilled and bolted, the forward spar of the vertical
stab, VS-402, must be aligned with and joined to the front spar of the horizontal stab,
HS-602 with joint plate F-681. At this point the tiny variations, between individual
aircraft become apparent, and the fore/aft match of the spars is seldom perfect. If
necessary, F-681 can be attached to the front of VS-402. If this does not solve the
problem, use a piece of aluminum sheet, up to 1/8" thickness between the F-681 joint
plate and either spar. Of course,longer fasteners must be used as well. If this does is still
not sufficient, a new F-681 may be fabricated with the bend in a different location. Do
not leave less than 2" above the bend. The portion below the bend must be sufficient to
bolt to both HS-610 and HS-614. The combination of these adjustments should
accommodate any reasonable mis-match.
Because of their position at assembly, the holes to attach the horizontal and vertical
spars cannot be drilled in assembly on the fuselage unless a 90 ｰ drill or some other
special equipment is used. The lower holes in F681 , those that bolt it to the horizontal
stab spar, should be drilled before assembly.
Although some aircraft designs offset the vertical stabilizer to counteract P-factor, we
prefer to align it with the centerline of the airplane. The different engine/prop
possibilities and the variation between individual aircraft make it impossible to provide
an offset that is correct for a given airplane. It is easier to trim the aircraft with a small
rudder tab as shown in Section 15. Before drilling, the vertical stabilizer forward spar
must be shifted until the stab is perfectly parallel to the fuselage centerline. This
alignment can be checked several ways, one of which is shown in Fig. 8-12. This consists
of attaching two strings to the fuselage centerline somewhere forward on the fuselage
and also to a bar clamped to the rear of the vertical stab. The vertical stab is determined
to be in line when both strings are in equal position on both sides of it. A similar check
could be done with just one string, switching from side to side for checking. Another
check is to mark the leading edge center of the stab skin with a marking pen. Then
visually look straight down the fuselage and move the stab until the mark is centered.
Checking the alignment of the vertical stab with reference only to the sides of the
fuselage adjacent to it will only be valid if the fuselage is in perfect alignment. (It is
possible to have a twist in the fuselage and still align the tail surfaces correctly to the
fuselage centerline.) With the position determined and re-checked, the spar can be
marked and the empennage dismantled for drilling.
Now the elevators can be attached and the elevator push rod F-690 can be finished.
With the control system in neutral position and the elevator in trail, the length of F-690
should be such that adjustment both ways is available in the rod end. However, over
half the thread should be engaged on each end, so it is impossible for a rod-end bearing
to thread off the push rod when both ends are pinned.
TRIM CABLE INSTALLATION
NOTE: If electric trim has been chosen, the trim cable is omitted from the Fuselage Kit.
The RV-6/6A manual trim control is a functional, though unconventional, vernier
control. A vernier is a control cable that rotates for fine adjustment, but has a button
that "unlocks" the threads and allows rapid push-pull movement. Most of us have
encountered verniers in other airplanes where they are commonly used as throttle, prop,
or mixture controls. Because the trim is very effective, it is conceivable that rapid trim
application while the airplane is traveling at high speed could produce high G loads,
possibly even destructive loads. Because of this remote possibility, the rapid push-puff
action of the cable should be disabled, leaving the rotational vernier action as the only
way to move the trim tab.
Pry up the rubber button with a small screwdriver. Work carefully because the button is
held with and adhesive and it is possible to damage the handle. When the rubber button
is out, remove the plunger shaft.
Without this shaft, the vernier control cannot be released and all action will be limited
to the twist screw function.
Replace the rubber button with a 1" chrome snap-in hole plug from the local hardware
store.
The trim cable is installed from the cabin end, starting through the center console and
then routing it aft through the fathead holes in the bulkheads. The fairlead holes are
shown on DWGs 26, 27, and 28.
Additional information is on DWGs 8, 34, & 40. Snap-in bushings of 7/16 l.D. are used
as fairleads in all of the bulkheads and webs through which the trim cable passes,
except at the root rib and rear spar of the horizontal stabilizer. The hole through the
root rib is at an acute angle not suited for a bushing, and the holes through the rear
spar must be of minimum size, not large enough for a bushing. Use RTV Silicone
Rubber to form a protective gasket around the trim cable in these passages.
Feed the cable through the fuselage and horizontal stabilizer and then through the
elevator spar and out through the opening in the elevator bottom skin (see DWG 5PP.)
Drill the Wd-415 the E-616PP cover plate. When the cable is completely in with its aft
end hanging free under the elevator, the Wd-415 Anchor Nut is threaded onto the cable.
With this anchor clecoed in place, the clevis end is threaded onto the shaft (just over
half depth) and trim tab travel can be tested. Desired down travel of the tab (nose up
trim) is 35 degrees, and up travel is 25 degrees.
The two inch travel of the control cable is sufficient for this total travel, but it may be
necessary to adjust the position of the cable by threading the Wd-415 anchor in or out
before it is finally riveted on. Even then, a little adjustment is available in the clevis end
fitting.
RUDDER CABLE INSTALLATION
Rudder cables are installed through the 7/16 l.D. snap-in bushings positioned in the
holes shown in bulkhead DWGs 15, 25, 26, 27, & 28. Because of the sizes of the end
fittings, the rudder cable must be installed from the rear to the front, as the front end is
the only one with a small enough diameter to pass through the fairleads. Note that the
rudder cables have been assembled with sections of polyethylene tubing on them.
These are used as fairleads where the cable exits the rear fuselage skin (DWG 34).
FUEL SYSTEM
The standard RV-6/6A fuel system is shown on DWG 49. "Standard" refers to a system
using a positive-G (non-inverted) fuel pick-up, low pressure fuel pumps, and float
carburetor. Since the tanks are below the level of the carburetor, a dual fuel pump
system is required. The system shown conforms to industry standards by using an
engine driven mechanical fuel pump as primary with a secondary electric "boost" pump
for use during starting, take-off & landing, and in case of failure of the primary pump.
Fuel lines are routed from the tanks, through the fuselage skins, to the fuel selector
valve. This valve is located in a central position making it easily accessible and visible
to the pilot. Fuel is then routed from the common "outlet" port of the selector valve to
the boost pump, and from there forward through the firewall, to the gascolator (fuel
filter), engine fuel pump, and carburetor. (Chapter 11 has more information about the
fuel system.) Inverted fuel systems will differ considerably. First, routing of fuel from
the tank with the inverted pick-up tube will be different. Chapter 7 included drawings
for installation of an inverted fuel pick-up tube, and a detail of this is included on DWG
40. The fuel selector valve can be the same, but the fuel boost pump and the primary
engine driven pump may have to be a higher pressure type, depending on the type of
carburetor or fuel injector used. Various pumps and components are available for use in
designing such a fuel system.
One unit manufactured by Christen Industries combines the functions of a hand
powered boost pump, fuel selector valve, and fuel filter. Because of the variety of
systems and components available, and because the RV-6/6A is not intended as a serious
aerobatic aircraft, detailed information on their installation will not be presented here.
BATTERY INSTALLATION
Battery installation is shown on DWG 48a. The location in the forward fuselage was
selected for center of gravity (balance) reasons, in addition to being conveniently located
to the electrical power needs. A sealed recombinant gas or gelled electrolyte battery
must be used to prevent spilling acid. See Van's Accessories Catalog., The battery box
used serves both as a battery hold-down and for electrical isolation. The use of any
battery not having the protective features of the Gel Cell battery would require a more
elaborate mounting box which must be sealed & vented to offer acid spill protection for
both crew and airframe. Significant variations in installed equipment, such as a very
heavy engine and/or constant speed propeller, may shift the empty C.G.
beyond forward limits. If so, the battery should be relocated to a more aft position,
probably in the baggage compartment. Sufficient structure will have to be provided to
insure the security of such an installation.
The actual battery box construction is straightforward and uncomplicated. It is made in
two parts, the base which is bolted into the lower front fuselage structure, and the box
or cover which attaches to the base via piano hinge pins. When the battery box base is
bolted into place it effectively stiffens the floor angle, particularly because of the
F-6120E plates which extend aft considerably.
The top portion of the battery box is fitted on the base before the piano hinge
attachments are positioned and drilled. The battery cover is installed or removed simply
by inserting or removing the piano hinge pins. The pins should be made at least 1 inch
overlength to provide a handle or tab to aid in installation and removal.
Section A-A1 of the drawing shows the approximate battery size. Since battery size
sometimes varies depending on the manufacturer and the production run, do not fit the
angle shown inside the box until a battery is installed. This angle, along with the plastic
strip riveted to its bottom side, is positioned so it contacts the top of the battery and
provides a hold-down. Similar plastic strips are riveted in as shims to the sides and ends
of the battery box to offer a firm, but not harsh, securing of the battery.
WING/FUSELAGE ASSEMBLY
During this phase of construction it is necessary to assemble the wings to the fuselage
for a number of reasons including drilling of the rear spar/center section attach,
finishing the flap control mechanism, installing the wing tank/fuselage attach brackets,
fabricating and fitting fuel & vent line, and installation of wing root fairings.
Actual installation of the wing panels to the fuselage should be very simple, as the spars
have been fitted and drilled. It is helpful to file a slight bevel on the root ends of the spar
to assist getting it started sliding through the slot in the fuselage bulkhead, and to
prevent it from scratching and galling the bulkhead side as it slides through. As the
wings are pushed in near center, be sure that the fuselage center bottom skin (which
overhangs the fuselage) doesn't catch on the wing skin. When bringing the spar into its
exact position, lining up the bolt holes in the bulkhead and spar, it is often helpful to use
drift pins. This could be a disposable hardware store bolt with the end rounded or
tapered on a grinder. Gently driving this into a nearly aligned hole will center the
bulkhead/spar hole so the NAS bolts can be installed without excessive force.
With the main spar bolted in place, the next step is the attachment of the rear spars.
Level the fuselage, both laterally and longitudinally, using the top longerons between
STA 30 and STA 55.75 as a datum surface.
Then square the wing with the fuselage. This is done by measuring from corresponding
points on the wing tips to a common centerline point of the aft fuselage, in a manner
similar to that shown in Fig. 8-10. Equate these distances at the same time checking
that the wings have no forward or aft sweep, prop plumb lines from the wing leading
edge at inboard and outboard points and check to see that they all fall in a straight line.
Mark this position with a vertical line at the rear spar attach, on both rear spar and
center section.
If forward sweep is encountered, determine why the rear spar will not go further into
the clevis. There is more than one possible point of interference. If necessary, the spacer
between F-605B and F-605C can be removed and trimmed. Edge distance on the bolt
hole is of little importance here, so the spacer can cut away until only 1/16" remains
between the bolt shank and the edge. If the upper corner of W-607D is a problem, it may
be trimmed as shown on DWG 14.
Now the very important incidence angle must be measured and set. Use a level and
spacer blocks as shown in Fig. 8-13. Rest one end of a level on the forward spar at the
skin butt joint and the other end on a 3.03" spacer placed directly over the rear spar web.
Shift the rear of the wing up or down to center the level. The spacer size has been
calculated to provide the desired 1 ｰ positive incidence angle. Check several points
along the span of the wing to verify the level reading. Clamp the root in place and check
the other side in the same manner. After checking and re-checking, drill the 5/16" hole
for the attach bolt. Initially drill an undersize hole starting with no more than a 1/4"
drill. Then progressively enlarge the hole to 5/16" to provide a dose fit for an AN5 bolt.
Drilling with a long stiff drill bit is a good idea because it can be held straighter for a
truer hole.
Drill the holes for attaching the fuselage bottom skin to the wing root rib as shown in
DWG 49. If the bottom skin is found to be oversize, it can later be trimmed to about 3/8
inch from the screw centerline. After disassembling the wing & fuselage, K1 100-08
platenuts can be riveted to the inside flange of the root rib, the skin and rib machine
countersunk, and the fuselage skin dimple countersunk to mate. The screw holes spaced
on 2 1/2" centers should fall between the rivets already in this rib, which are at 1 1/4"
intervals.
The F-696 fuel tank mount bracket can be cut to the size shown on DWG 46 and fitted to
the fuselage. The wing attach flange of this angle is to be located aft of the
corresponding flange of the fuel tank bracket and the fuselage flange is to face forward.
The F-696 bracket must attach to high strength components in the fuselage, which in
this instance are the forward bottom longerons. However, as can be seen in Section B-B1,
the F-650 longeron is too low for the F-696 to contact without protruding outside of the
wing root fairing.
Thus, an angle stiffener has been added between the two longerons which provides a
rigid attach point for the lower part of the tank bracket.
This is shown both in the top view drawing and the Section B-B' drawing. The top of this
angle is attached in common with the bolt holding the F-696 bracket, and the bottom of
the angle is attached with a flush head AN509-8R12 machine screw. A 1/8" thick spacer
is required between the angle and the skin at the lower bolt where the lower bolt is
drilled through the bracket and angle.
The F-696 bracket is made from a standard 90 ｰ angle aluminum extrusion, which must
be bent slightly to account for the angle between the wing root rib and the fuselage at
that point. Then it can be clamped firmly to the corresponding bracket on the fuel tank
and drilled to the fuselage.
Drill the holes for the F-696 bracket from inside the fuselage because, with the wing and
tank in place, outside access is limited unless a 90 ｰ drill drive is used. Even then, we
recommend drilling a pilot hole of perhaps 1/8" and then enlarging it by back drilling
from the fuselage inside in order to achieve truer holes than an angle drive can achieve.
After the F-696 is bolted, at least temporarily, to the fuselage, the clamp can be removed
and the 1/4" hole drilled through the mating flanges of the two brackets. Center this
hole in the overlapping portions of the brackets, and use a "D" drill to achieve a snug fit
of the bolt.
Remove the tank and slot the T-405 bracket as shown on DWG 46. This slot will allow
the wing to pull away from the fuselage without tearing out the inboard tank rib and
spilling fuel.
Fabricate the fuel and vent lines by cutting the soft aluminum tube to length, bending
as required for routing, and flaring the ends for fittings. A 37° flaring tool is required
and a good tubing bender is desirable.
Remember to install the AN819 sleeves on the tubing before making the flare! Where
required, install AN931 grommets on the lines before installing the final end fittings.
Avoid making sharp bends in the tubing as it will tend to collapse and restrict the flow.
The holes cut in the fuselage skin for the vent and fuel lines should be 3/4" and 1"
respectively for mounting the grommets which seal the holes once the lines are
installed.
FLAP ATTACHMENT
Install the flaps on the wings, then fabricate and fit the linkages. Access holes for the
flap link will have to be cut in the fuselage bottom skin. DWGs 40,42 and 46 illustrates
the installation of this linkage. Because the flap link is installed at an inclined angle,
cutting of the access holes will require some careful measurements and maybe some
guessing. First cut (or drill) minimal size holes and run a wire or small rod through to
check alignment of the holes and the flap and actuator. Enlarge the holes as necessary
to install the flap link (for minimum size hole, install with bearing off one end) then
move, or attempt to move, the flap handle through its full range. Enlarge the holes as
necessary to permit full movement of the flap without interference. Adjust the links
length with the rod end bearings so the flaps are in full up position at the time the flap
handle is full down. Maximum flap deflection should be 42 ｰ-44 ｰ, which under flight
loads will yield slightly to possibly 40 ｰ.
Once all fitting is complete, the flap bottom skin (left oversize during initial
construction) can be trimmed so it laps over the fuselage bottom by 1/2 to 3/4 inch. The
flap bottom skin provides its own fairing to the fuselage and the overlap skin also covers
the flap actuator hole.
WING ROOT FAIRINGS
As a general rule, aircraft which have wing/fuselage intersections of 90 ｰ or more do not
need elaborately shaped wing root fairings arid trailing edge fillets. Since the RV-6/6A
wing/fuselage intersection approximates this condition back to a point around the rear
spar, we provide simple, flat aluminum fairings. They are a compromise of esthetics,
building ease, and aerodynamic efficiency. These are shown on DWG 46.
Use the dimensions as a guide, but make the final cut by scribing a line on the fairing
that fits your fuselage.
Pay particular attention when wrapping the fairing around the leading edge. It must be
kept tight to the contour of the wing and it helps to have two people holding it in place
while the final cut line is marked.
Flush head screws are used to attach the fairing to the wing. Think and measure
carefully before drilling for these fasteners. Nutplates must be installed on the inboard
wing rib, which is fluted. Layout a spacing that allows the nutplates to miss the flutes,
but still looks regular and pleasing from the top.
EMPENNAGE FAIRING
A molded fairing, F-694, is supplied with the finishing kit Because this fairing covers
the intersection of the vertical stabilizer, horizontal stabilizer, and fuselage, any
variation in the position of any of these surfaces can cause a misfit. This fairing will
usually require some reshaping or additional fiberglass work to fit precisely. It may also
be necessary, during test flying, to reposition the leading edge of the horizontal
stabilizer to correct pitch trim. If possible, we recommend taping this fairing in place
during the test period and doing the final fitting when the airplane is "trimmed out".
The F-694A lower stabilizer fairing shown on DWG 46 is simply a piece of scrap 0.025
sheet (you have some by now, no doubt) trimmed to fit the bottom of the horizontal
stabilizer. Holes drilled through the fairing into the longerons are tapped for a #6 flush
head screw. A recess is made, through the skin into the longeron, with the microstop
countersink, and the fairing is dimpled for the screw head.
CONTROL STOPS
DWG 16 shows the installation of an aileron control stop. The stop consists of a piece of
aluminum approximately 1 inch square and 3/16 or 1/4" thick, which is riveted to the
outside edge of aileron bracket W413. The top view of the aileron at the top center of the
drawing also shows this control stop. The procedure for locating the position for the stop
is to move the aileron to its maximum up limit and hold it there while installing the
stop. As shown, the stop block should squarely contact the edge of the A-407 bracket.
The desired aileron travel is shown in Section 15 (see the Preview Plans if you don't
have a Finishing Kit yet).
Aileron control stops are needed for up travel only. The travel of the opposite aileron and
the differential movement of the system determine the down travel. Control surface
deflection is easy to measure with a digital "smart level". Center the control surface in
the neutral position, set the level to zero, and move the surface to the desired deflection.
DWG 34 shows the fabrication and installation of control stops for the elevator.
Elevator travel is shown in Section 15. The angle supporting the vertical stabilizer
doubles an up stop. The spacer between F-614 and the angle on F-61 1 is cut to the
correct length, determined by the control movement, to serve as a down stop.
Both up and down stops contact and restrain the elevator horn at the extremes of its
travel. It is often necessary to trim the flanges of the HS-603PP rear spar channels to
allow the elevator horns to swing far enough to achieve full travel. Trimming the flanges
is perfectly permissible, but the HS-609PP bars must NOT be trimmed or damaged.
Rudder stops are cut from AA6-125x1x1 angle and are riveted to the lower longerons
as shown on DWG 34.
They are to be trimmed so their horizontal flange contacts the rudder horn squarely at
the limit of its travel which travel is shown in Section 15. Control surface travel can be
determined through the use of templates.
These templates can easily be made of cardboard, using the airfoil drawings for the
empennage and wings to get the desired contours. One reason for positive rudder stops
is to prevent interference with the root ends of the elevators, and possible catastrophic
jamming.
COCKPIT HEATERS
Cockpit heaters are a builder option for the RV-6/6A, and some thought should be given
to cabin heating prior to completely finishing the fuselage. Even if you fly mostly in
warm summer weather, the RV-6/6A easily operates at altitudes where a heater is
extremely welcome. The exact details of your system depend on your engine and
exhaust system. Exhaust Heat Muffs and Cabin Heat Boxes are available through Van's
Accessories catalog. More information on the installation of these and similar systems is
included in Section ll.
COCKPIT ALTERATION FOR EXTRA TALL PILOTS
The RV-6/6A cockpit has been designed to comfortably seat pilots and passengers of up
to 6'4", and possibly up to 6'6" heights. This of course assumes pilots of average
proportions. Those of less than maximum acceptable heights but with unusually long
legs or torsos may find the cabin space to be cramped in that dimension.
In the interest of construction ease, the RV-6/6A seats are not adjustable in the same
sense as automobile seats. The seat backs are designed for ground adjustment through
a 3" range. Short pilots may need additional back cushions in order to reach the rudder
and brake pedals. Pilots with extreme leg room requirements can gain space by
relocating the rudder pedal assembly forward and by altering the lower firewall with
recessed areas for forward rudder pedal swing.
Most pilots of 6' to 6'2" height use a firm cushion of 3-4" thickness. Taller pilots can use
cushions as thin as 1" with reasonable comfort because of the general "bucket" contour
of the seat bottom. Persons up to 67" have flown in the RV-6/6A. Those with headroom
requirements exceeding the 39 1/2" available can gain another inch or so by building a
recessed area into the seat bottom; sort of a "bucket within the bucket seat"
arrangement. Again, Van's Aircraft Inc. should be contacted for specific help in this
regard.
AIR SPEED & STATIC SYSTEM
The air speed pilot system and lines are shown in the wing plans. The pilot line runs
along the forward side of the wing spar and is intended to continue on into the fuselage
and up along the forward side of bulkhead F 604, then forward along the upper longeron
to the instrument panel. Or, it could enter the fuselage and run forward to bulkhead
F-602 before going up to the instrument panel. Clear plastic line, available from most
hardware and automotive stores, is readily available and easy to use material for this
line. Or a more permanent line of aluminum tube and fittings could be used if the
builder so desired. Surgical tubing can be used in lieu of tube fittings in connecting
aluminum lines at junction points such as wing to fuselage.
For the most accurate possible airspeed readings, a remote airspeed static system
should be used. When the air speed static is vented directly to the cabin, inaccuracies
can result because cabin pressure varies from ambient (atmospheric) due to air leaks
and ventilation systems. Sometimes static vent lines are routed into the wings, but this
does not assure an ambient source. A better method is to route the static line to an
outlet located at some neutral pressure point on the airframe, usually somewhere on the
aft fuselage. By trial-and error, a position for this has been located on the RV-6/6A
fuselage as shown in Fig: 8-15. The vent ports are just SD-42BS-LF Pop-rivets, set in
the fuselage side skin. Their broken mandrels are driven out to provide an opening and
1/8" l.D. clear plastic tubing (hardware store variety) is slipped over the protruding ends
of the rivets and sealed with RTV Silicone Rubber, The lines are joined at the right side
with a 1/8" plastic Tee fitting, also hardware store variety, and slip-over links of 1/4" O.D.
clear tubing. Then a 1/4" O.D.
polypropylene tube (milky white color) is slipped over the remaining outlet of the Tee,
and routed forward to the instrument panel following a course through several
bulkheads, just below the top longeron. Use NYLOSEAL fittings to connect the static
line to the airspeed, altimeter, VSI and other pressure instruments. Kits for this system
are available from Van's Accessories Catalog.