SECTION 7
RV-8/8A
7-11
8s7-1r11 06/13/11
counterbalance pipe in place. Match drill the skins to the skeleton including the #30 holes in the counterbalance
pipe. The holes along the bottom of the spar are opened to #30 for the CS4-4 blind rivets. Remove the trailing edge
portion and re-cleco the leading edge in place with the counterbalance pipe in position. Using a long 1/8” drill, go
through the lower hole that attaches the A-704 nose rib to the spar and drill through the tab on the rib into the
counterbalance pipe.
Disassemble the parts, deburr, dimple and prime as needed. Machine countersink the holes in the counterbalance
pipe. The countersink need not be 120° to match that of the rivet heads. The .020” skin and the aluminum blind
rivet will deform sufficiently to contour to a 100° countersunk hole.
Attach the nose ribs to the counterbalance with blind rivets. Bend the tab on the nose rib juse enough to clear the rivet tool.
Cleco the leading edge skin to the counterbalance/rib assembly, rivet the nose ribs to the to the spar. Cleco the aft
skin to the spar. Leave out the main ribs and the clecos along the bottom of the spar to allow access to the inside.
Rivet the leading edge skin and tariling edge skin to the top of the spar. Rivet the nose ribs to the the top half of the
nose skin only. Insert the main ribs and rivet them to the spar and top of the aft skin. Install the A-406-1 and A-407 brackets.
Flip the assembly over, cleco it together and weight it down on a flat work surface. Blind rivet the counterbalance
pipe to the leading edge skin. Keep checking that the aileron is flat. Rivet the bottom side of the nose rib to the skin.
Rivet the bottom side of the main ribs to the aft skin. Last, blind rivet the leading edge and aft skins to the spar.
FLAPS
Flap details are shown on DWG 14B. The flaps are the easiest control surfaces on the RV-8/8A to build. The only
jigging required is a level, flat surface at least 5' long and 1' wide. Easy or not, it is possible to build in an
unacceptable twist, so work with care.
Prepare the FL-803PP-1-L&R flap spars by deburring the lightening holes and polishing the edges.
Drill and cleco the FL-704 and FL-705 ribs to the spar then cleco the assemly to the FL-802PP-1 bottom skin. Make
the FL-708 spacers that go between the end ribs and the bottom of the top skin. The aft edge of the ribs should
contact the “rear spar" bent into the bottom skin. Thin shims between the aft end of rib and the rear spar are
acceptable.
After making any necessary shims, drill the ribs to the rear spar.
Drill the ribs to the bottom skin. The line of rivets along the bottom of the spar holds the hinge that will connect the
flap to the wing. Drill and cleco on the hinge as well. Pinning the two halves of hinge together while drilling will help
hold the hinge straight.
Instead of dimpling the bottom of the spar, dimple the skin and machine countersink the spar, with the hinge clecoed
on to serve as a guide for the countersink pilot. The soft hinge does not have to be countersunk or dimpled.
Fit the FL-801PP-1 top skin to the assembly. Cleco the top skin to the spar, align the holes along the ribs and drill
these before drilling the line along the bottom of the flap.
Fabricate the FL-706A. Fit the FL-706A and FL-706B to the inboard rib and inboard end of the spar. Rivet the FL-
706A to the spar with the AN rivets only, leaving the holes that will attach the rib open.
After the necessary dimpling, priming, etc., begin riveting the flap together. A cradle, made with simple V-blocks like
those used in the empennage, is a useful aid. Put the flap in the cradle and remove the spar to gain access to the
rear row of rivets that join the top and bottom skins. Rivet the interior ribs to the skins, but leave the end ribs
clecoed.
Rivet FL-706B and the platenut to the inboard FL-704 rib, then rivet the rib to the skins...you must set these rivets
before “closing the door” by putting the spar in place.
When all the ribs are riveted to the skins, rivet the spar to the ribs with blind rivets, then rivet the spanwise lines that
join the spar and hinge to the skins. Finish riveting the end ribs.
Expect to trim the upper skin of the flap slightly when the wing is mated to the fuselage, but for now, leave it
untouched.
NOTE:
The bearing CM-4MS, shown on DWG 14B, is supplied in the fuselage kit, not in the wing kit.
ATTACHING AILERONS TO THE WING
Completely finish the flaps and ailerons before mounting them to the wing.
RV-8/8A
SECTION 7
7-12
8s7-1r11 06/13/11
Set the wing, with the leading edge and the top main skins riveted on, on a workbench, topside down.
Assemble the W-816 and W-818 pushrods as shown in DWG 15A. Prime both pushrods inside and out. Cover the
inside by pouring a small quantity of primer inside the rod and slowly swirling it around. Rivet the AN49OHT8P or
VA-169 rod ends to the pushrod.
Make sure the primer is fully cured, then thread the rod-end bearings and jam nuts on. Temporarily tape the
pushrod where it passes through the rear spar, so when aileron is removed the primer won't be scraped away.
Install the WD-421 bellcrank as shown on DWG 15A. The bushing in the WD-421 needs to be reamed to final size
for the slip fit on the AN4 bolt. The bushing should be slightly longer than the WD-421 aileron bellcrank. It is held
firmly between the bellcrank brackets with the bolt. The bellcrank rotates around the bushing, not the bolt. This is
the same way that the stick assembly is done also. Lubricate the bushing with your favorite grease when
assembling for the final time.
Connect the W-816 and W-818 pushrods to the WD-421 bellcrank. Use the W-730 bellcrank jig provided to set the
bellcrank in the correct neutral position. Use the alignment tool you built at the beginning of the wing construction to
position the aileron in the neutral position. Clamp the aileron in this position and adjust the rod end bearings on the
W-818 push rod until the pivot bolts at the bellcrank slip in smoothly. Tighten the jam nuts and label the push rod
right or left as appropriate. Final adjustments will be made to the W-816 push rod later, when the wing is installed
on the fuselage.
ATTACHING FLAPS TO THE WING
There are two good methods of installing the flap hinge pin. The choice is yours.
Drill a small hole in the W-413 aileron hinge bracket assembly for the flap hinge pin to just go through. You will not
be able to get this hole exactly in line with the flap hinge line, but this is a good thing. Drill the hole in the
approximate position and when you insert the hinge pin for the flap, the pin will spring into position after being
pushed all the way through and not be able to come out on its own. You may have to disconnect the aileron
pushrod in the wing to remove this pin after the aircraft is fully assembled. This will allow you to swing the aileron
out of the way for pin removal.
An alternative method is to remove one hinge eye at the center of the flap hinge and two hinge eyes at the center of
the wing hinge. This will allow you to get two hinge pins in from the center of the flap, one in each direction. Bend a
small portion of the hinge pin at a right angle to grasp with pliers as you slide the pin into place. With the flap
hanging down the hinge is accessible from the opening at the top. Push the bent portion of the pins forward to lie
on the inside of the skin. Drill two small holes in the skin and safety the hinge pins in place.
WING TIP INSTALLATION
Delay wing tip installation until late in the construction process, preferably until the aircraft is nearing final assembly.
This prevents the possibility of damage from handling and gives every opportunity for the installation of lights, wing
tip antennae, etc.
The tips may be installed with the wing lying down on a table or with a wing positioned in a cradle style storage
fixture. See DWG 12A.
The aileron control system is used to neutrally position the aileron, which helps to position the wingtip. Use the W-
730 Adjustment Fixture to locate the aileron in its neutral position and hold them in place with a bungee cord.
Sand or file the flange on the W-715-1 tip so it is an even depth and width all around.
Portions of the aft end of the W-715-1 tip must be trimmed away to provide clearance from the aileron and W-414
Aileron Hinge Bracket.
Slip the W-715-1 tip into place. Push it forward so it is tight in the wing leading edge and align the trailing edge with
the trailing edge of the aileron. An assistant is helpful.
Drill the W-715-1 tip using a #40 drill. Begin at the leading edge and work to the back. Alternate holes from the top
to the bottom. If you are unhappy with the placement of the tip, adjust it slightly when the holes are drilled to full
size.
Swing the aileron out of the way and slip the W-412 tip rib (DWG 17A) into place. Mark the location of the rib
