by David Barnhart and Frank Justice
Notes on building a jig for the empenage:
If you plan to build your wings on the same jig, for an RV-6 the
distance between the inside surfaces of the posts should be at
least 108". For the RV-4 it should be at least 117". The empenage
can be built on a free-standing jig with leveling feet if you
are an apartment dweller. Make the feet on the supports at least
36" long. Building the Horizontal Stabilizer Rear Spar
Written by: Parts Preparation
RV-6 SN 23744
With a few added notes by FKJ.
Prepairing the Jig:
- HS-606 Tip Ribs: Bend all flanges perpendicular to the web. Flute
the ribs to straighten them.
- HS-607 and HS-404 ribs: Bend the long flanges (not the aft-facing
flange) perpedicular to the web. Flute ribs to straighten.
- HS-608 and HS-405 ribs: Bend the long flanges and the aft-facing
flange perpendicular to the web. Flute ribs to straighten.
- Debeurr all edges. Round any sharp corners on the ends of the
- HS-409: Use Scotchbrite or fine Emerycloth to remove any tooling
marks from the HS-409's. polish the edges so they are slightly
rounded. File, sand, or polish the ends to remove the sharp corners.
Be careful not to remove too much material from the end corners.
ideally, the ends should each form a 1/2-inch diameter semi-circle.
Prepare the HS-603 Spar Channels and Fasten Them to the Jig
- This assumes that you have built a suitable jig as described in
Van's Construction Manual. In this step, you will draw lines on
the surface of the jig's horizontal crosspiece member. These lines
are used later to accurately position and align assemblies. Drawing
thin, straight, accurate lines will be made easier if you fasten
a four-inch-wide strip of melamine to the top surface of the jig's
crosspiece. Melamine is typically Partical Board coated with a
thin veneer of a white plastic-like substance.
- Begin by drawing a straight line down the center of the Jig's
horizontal crosspiece. An easy way to draw this line is to use
a carpetner's chalk snapline, then overlay the chalk with a line
drawn with a Sharpie pen.
- At the center of the crosspiece, and exactly perpendicular to
the spanwise centerline you just drew, draw a second line. This
will be the 'vertical' centerline of the spar. The two HS-603
spar channels will join at this vertical centerline.
- Draw four more lines on the jig exactly perpendicular to the spanwise
- 19-15/16 inches left of the vertical centerline
- 19-15/16 inches right of the vertical centerline
- 42-11/16 inches left of the vertical centerline
- 42-11/16 inches right of the vertical centerline
- These four lines will be used later to locate the HS-412 and HS-413
Prepare the HS-409 Flange Strips
- Locate and draw a line down the spanwise centerline of each HS-603,
as shown in Van's Construction Manual. The line should be on the
same side of the HS-603 as the flanges. An easy way to locate
the spanwise centerline is to use a center-finding rule.
- File a small (1/8 inch) notch in the inboard end of each HS-603
at the centerline. Lay the HS-603 spar channels on the jig, flange
side up. Butt the inboard ends together, aligning the centerlines
of the HS-603's with the spanwise centerline on the jig. The inboard
ends of the HS-603's should meet at the vertical centerline drawn
on the jig.
- NOTE: It is not important that the inboard ends butt perfectly.
In fact if the inboard end of the HS-603 is not cut exactly perpendicular
to its centerline, the two HS-603's will not mate perfectly. This
does not matter. What does matter is that the spanwise centerlines
of the HS-603's be exactly aligned over the spanwise centerline
drawn on the jig crosspiece. Also insure that the overall length
is as shown in the plans.
- Drill a #40 hole in each HS-603 on its centerline approximately
3 inches in from the outboard end. Cleco the HS-603's to the jig
using this hole.
Prepare the Hinge Brackets
- Locate and draw the vertical centerline on each HS-409. Following
the instructions in Van's Construction Manual, mark and pilot-drill
the rivet holes in the HS-409's. Use a #40 drill bit, and be sure
not to drill the holes shown on the plans for the fuselage attachment,
HS-411's, HS-412's, Hs-413's hinge brackets, etc. Find the way
the flange strips fit the best against the spar channels; the
taper may be slightly different on the sides of the strips. Remove
enough material from one edge of each HS-409 so it lays flush
against the flanges of the HS-603's. Lay the HS-409's in the spar,
aligning the vertical centerlines of the HS-409's with the inboard
ends of the HS-603's and vertical centerline drawn on the jig.
Using a #30 drill bit, and the pilot holes as a guide, drill through
the HS-409's and HS-603's. Insert a cleco in each hole, fastening
the assembly to the jig.
- Do not prime or rivet these parts yet.
Aligning the HS-413 Hinge Brackets
- Follow the instructions in Van's Construction Manual to prepare
the HS-411, 412, and 413 hinge brackets. This includes priming
the HS-411's, mounting the VA-146 bearing between the two HS-411's
and riveting these three parts together.
- When drawing the centerlines on these hinge brackets as described
in Van's Construction Manual, be sure to do so with a high degree
of accuracy. A carpenter's square is very helpful for this process.
Locate, drill, amd cleco the inner HS-413 hinge brackets to the
spar as described in Van's Construction Manual. Use an adjustable
carpenter's square and the perpendicular lines previously drawn
on the jig to help you arrive at spanwise alignment. Use the centerlines
drawn on the HS-413's and the spanwise centerline on the spar
to help you arrive at the 'vertical' alignment. Aligning the HS-411 Assembly and Inner HS-412, 413 Hinge Brackets
Mount remaining HS-412 and HS-413
- Using the technique shown in Van's Construction Manual, locate
and align the HS-411 assembly and the inner HS-412 and 413 brackets
on the spar. The perpendicular lines drawn on the jig earlier
will help you do this. An alternative to using the drilled bolt
(described in Van's Construction Manual), is the "Hinge Line Alignment
Bushing" set, available as order number 10745 from Avery.
- When everything is accurately aligned and clamped to the jig,
drill and cleco the parts.
Prime and Rivet
- Use the technique described in Van's Construction Manual using
a rod-end and washer to locate and align the remaining HS-412
and HS-413 hinge brackets.
- Clamp the parts to the jig.
- Drill and cleco the parts to the jig.
Prepare the HS-602 Front Spar Channels and Fasten Them to the
- NOW (yes finally), remove all clecos. Alumiprep (and optionally
alodine), and prime all parts (except the HS-411 assembly which
was primed earlier). Rivet everything together.
- By far the best way to rivet the parts together is by using the
'Avery Tool' instead of trying to squeeze the 1/8" rivets with
a hand squeezer or using a rivet gun.
Fabricate the HS-610 and HS-614
- Drive a nail into the melamine at each end of the jig crosspiece.
The nails should be driven through the spanwise centerline drawn
on the surface of the melamine. Connect a taught string between
the two nails. You now have two spanwise centerlines perfectly
aligned with each other: one drawn, the other in string.
- Prepare the HS-602 front spar channels according to Van's Construction
Manual bye marking thier spanwise centerlines and creating the
'tongue' on the inboard ends. Mount the HS-602 spar channels flange
side down on the jig crosspiece, aligning the centerlines drawn
on them with the centerlines on the jig.
Assemble the Front Spar
- Fabricate the HS-610 and HS614, but do not put the bends in yet.
Locate and drill the holes with a #40 drill bit. Note that four
holes marked "Drill in assembly with fuselage" should not be drilled.
Position the HS-610 and HS-614 on the spar channels, making sure
you have them placed exactly as shown in the plans. Clamp them
in place. Using a #30 drill and the #40 pilot holes as a guide,
drill out the rivet holes inboard of where the bends will be.
eight holes in the GS-610 and eight in the 614.
- Remove the HS-610 and 614 from the jig and put the 6 degree bend
- Support the 610 and 614 on a block several inches high, and cleco
them to the HS-602 spar channels. Be sure to add a couple of extra
clamps on each side of the bend in the HS-610 and 614 so that
the spar channels will lay flush in the bend. Using a #30 drill
bit and the #40 pilot holes as a guide, drill out the holes in
the HS-610 and HS-614 outboard of the bends.
- The inboard four rivets on the HS610 and the inbaord two rivets
on the HS614 will be AN426 (flush) rivets with the flush head
facing aft. Dimple these four holes in the HS602's. Machine countersink
the corresponding holes in the HS-610 and 614. If you have a 120-degree
countersink bit, you'll find the back side of the dimple (in the
HS602) will fit better than if you countersink with a normal 100-degree
- Prep and prime the HS602's and HS-610 and 614. Rivet them together.
Assembling the Horizontal Stabilizer Skeleton
- Mount a centerpost on your jig according to the instructions in
Van's Construction Manual. The surface of the centerpost facing
the skeleton should be perfectly plumb (vertical).
- Fabricate a pair of brackets shown in Figure 6.9 in Van's Construction
Manual, and mount them on the jig uprights in their approximate
positions. Fabricate five brackets (also shown in Figure 6.9)
and mount them on the jig crosspiece. These five brackets should
be positioned so that when the rear spar is mounted on the jig,
each bracket will fit between its associated HS411, 412, or 413
hingle bracket pair. It is EXTREMELY IMPORTANT that these five
brackets are aligned perfectly. Run a string through their holes,
making sure that the string passes through the exact center of
the hole in each bracket. Make sure that the centerline of each
bracket is aligned with the spanwise centerline drawn on the jig.
An alternative to fabricating these five brackets is to ppurchase
them ready-made for about $20 from Avery.
Skinning the Horizontal Stabilizer
- Mount the rear spar to the five brackets on the Jig's crosspiece.
Locate, drill, and cleco the HS-606, 608, and 405 ribs according
to the plans and Van's Construction Manual. Enlarge the fwd tooling
holes in the HS-606 ribs to accomodate the threaded rod on the
brackets you mounted on the jig uprights in the previous step.
- Place the front spar on the rear spar/rib assembly. Note that
the plans show several dimensions you should use to get the distance
between the front and rear spars correct at the tip and root,
and to get the angle of the HS-405 ribs correct.
- Make sure that the distance from the centerpost to the spanwise
centerline of the rear spar is the same as it is to the front
spar. Drill and cleco the front spar to the HS-606, 608, and 405
ribs. Locate drill, and cleco the HS-404 and 607 ribs.
- Remove the clecos, drill and prime everything, then rivet the
skeleton together, excpet for the HS-404 ribs. Do not rivet the
HS-404 and HS-405 ribs to the front spar at this time. The HS-404
will later be removed to make it easier to rivet the skin on.
Horzstab.doc 4/7/95 David Barnhart, Frank Justice
- Make three simple wood clamps as shown in Van's Construction Manual.
Duct tape may work beter than foam weather strip to line the cutout.
- Place the left skin on the left side of the skeleton. Clamp the
skin to the skeleton. Shift the skin laterally until the proper
overhang at the trailing edge is achieved.
- Clamp the skin to the skeleton very tightly using the wooden clamps
and several C-clamps. Remove the clamps from one side only. Peel
the skin up on that side and using a Sharpie felt pen, trace the
pattern of the ribs and spars on the backside of the still-clamped-down
side of the skin. Mark the location of each flute. Mark the locations
of the HS-411, 412, and 413 hinge brackets. Reclamp the skin back
down, remove the clamps from the other side, and repeat the procedure.
- Remove the clamps, and remove the skin from the skeleton. Lay
the skin on the bench. Mark rivet lines on the backside of the
skin. The rivet lines should be 1/4 inch from the edge of the
flange of each rib/spar.
- Mark the rivet spacing, being mindful of the positions of the
flutes and hinge brackets. Do not locate a rivet over a flute,
or directly in line with a hinge bracket.
- Now draw a line down the flange of each rib/spar 1/4 inch from
the edge of the flange.
- Using a #41 drill, backdrill the rivet holes through the skin
from the back side.
- Place the skin back on the skeleton. When you have the skin correctly
aligned, you should be able to see the rivet line drawn on the
rib/spar flanges through the rivet holes in the skin. Clamp the
skin in place. Using a #40 drill and the #41 pilot holes as guides,
drill through the skin into the ribs.spars. Put a cleco in each
hole as you drill it.
- Remove the skin from the skeleton. Deburr the holes. (Scotshbrite
should be sufficient to deburr the holes in the skin.) Use the
Avery Tool to dimple all the holes in the skin. Use a hand squeezer
to dimple the holes in the skeleton. Prime the backside of the
- Place the skin back on the skeleton for the last time, clecoing
it down. Remove the clecos from one side, and rivet the skin to
the skeleton on the clecoed side.
- Now for the other side. Starting at the tip, rivet the skin to
the front spar. Two holes on each side of the hole you are working
on should contain clecos. The remaining rivet holes should not
be clamped dow, so that you can peel the skin back to get your
arm in there and buck the rivets.
- Rivet your way inboard untill you are about 2/3 the way to the
HS-608/607 rib. Then alternate between riveting the skin to the
front spar and riveting it to the aft end of the tip rib. When
riveting the skin to the tip rib, start at the junction with the
front spar, and work aft (down).
- After you have finished all the rivets between the tip and the
HS-608/607 rib, finish the rivets in the tip rib forward of the
front spar. You may find it difficult to get a rivet squeezer
in position to squeeze the last one or two rivets at the leading
edge. There are a couple of techiques you can use. You can grind
the jaws of a pair of Vise-Grips smooth and use it a a rivet squeezer.
If you have a pneumatic rivet squeezer or Avery's new hand squeezer,
you can get a 'no-hole' yoke for it.
- Go back to riveting the skin to the front spar. When you get about
1/3 the way to the root rib, alternate between installing a rivet
in the front spar and the HS-405 rib. When riveting the skin to
the HS-405, start at the junction with the front spar, and work
- After riveting the skin to the entire front spar, rivet the skin
to the HS-607 rib. This is why you left out the HS-404 rib: so
you could get in there with your hand to buck the rivets on the
- Rivet the HS-404 rib to the front spar. Using a hand squeezer,
rivet the skin to the root rib and rear spar.
- Now that you've done the left skin, repeat this process for the
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