VELOCITY XL FG
N478B
FUEL SYSTEM
The standard
Velocity XL FG has two wing fuel tanks in the strakes, each carrying about 33
galllons of fuel. These drain to a
common sump tank that carries another 4 gallons for a combined total of 70
gallons. These tanks can be modified and increase the
total fuel capacity to 90 gallons.
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I installed the hard points
per the manual. Since I did not have an
engine yet, I installed a return point in case I ended up installing a
Continental. During tapping of the hard
points, I noticed delamination of an area of epoxy surrounding the last hard
point installed. I am not sure of the
cause for this. I probably did not
prepare the surface properly or the epoxy hardener might not have been good, as
I found out later. In any case, I
removed all the delaminated lay-up and reinstalled the hard point. I then decided to level the area with
microglass and cover the internal sump tank surface with one ply of fine BID
and finish with peel ply on the overlapping edges. Although a little heavier, I am confident
this will maintain the integrity of the internal sump tank’s surface. I relocated the vent line to the top of tank
and installed the low fuel warning sensor as high as possible in an attempt to
avoid trapping air at the top and false low fuel warnings. Any unnecessary tapped hard points I will
seal later.
2. Tank Cover (1)
I glued the tank cover with
a mixture of epoxy and cabosil (mayonnaise consistency). After curing, I rounded the edges with a 36
sanding wheel on the air grinder and glassed the edges per the manual,
finishing with peel ply.
3. Mounting
Tabs (1)
Made per the manual on the
bench.
I removed the inner skin
and foam on the fuselage floor to clear the fuel drain hard point installed
outside the tank's bottom. I placed duct tape on the sump tank’s
bottom surface and pushed the duct tape covering the hole for the drain valve
to mark the place for the access hole. I filled the cavity in the
fuselage with micro, installed the sump tank in place and left for curing. I opened the fuselage hole for the drain
valve based on the mark left by the hard point.
The area of the hard point now sits on this bed that adapts perfectly to
its shape.
5. Fuel Drain
Valve (1)
The mark on the bed
described above, guided the opening for the fuel drain. I initially opened it with increasingly
bigger drill bits and then with the Dremel tool. For the most part, the valve is protected
within the fuselage’s wall.
FUEL STRAKES Working (1)
(2) (3)
Right Strake
I used an adjustable roller
stand for support and got the wing to 0° incidence with a digital level.
2. Lower Strake
Fitting (1)
(2) (3) (4) (5) (6) (7) (8) (9)
Started cutting the
fuselage side of the strake marking and cutting per the manual. Facilitated the process supporting the
fuselage side of the strake with small blocks of 2”x2” hot-glued to the
fuselage. The inboard side was easy. One just needs to be very accurate when
marking the cut line. I would cut with
the airsaw and finish with a new 36 grinding wheel, first on the air grinder
and then by hand. The outboard cut
though is tricky. Careful measuring is
necessary front-rear for leading edge matching and up-down for wing
matching. I went very slowly at the end,
leaving it a little long, and I am glad I did.
Once the bottom strake shell clears the wing, it will shorten the width
of the strake and change the matching dramatically, especially toward the
leading edge. This is because the strake
is much thicker than the matching wing, due to the thickness of the foam, and
it is rather displaced from final position until it clears the wing.
3. Lower Strake
Preparation (1)
I use the 90º air grinder
with a used 80 grinding wheel wherever I can to reduce sanding. I use my fingers as trigger-stoppers to limit
RPMs and control grinding.
4. Lower Strake
Glassing (1)
(2) (3) (4) (5) (6) (7)
I use a tongue depressor to
form the micro transitions and peel ply everywhere for edge finishing and less
sanding.
5. Upper Strake
Matching (1)
I warmed the outboard area of
the upper strake shell with a heat gun and placed weight on it to increase the
curvature to better match the wing. This
worked better than expected. I
inadvertently let the top strake move when measuring in place and ended up
cutting too much material on the outboard side.
I took the part I had cut from it with the air saw and glued it back in
place with micro. Once cured, I
reinforced it with 2-BID glass on the inside and grinded it to the correct
size.
6. Strake Door Cut (1)
(2) (3)
I marked the leading edge
of the strake, at the wing cord, 10° aft of its intersection with a square
angle located at the door opening line.
I used a laser line to draw the cut line joining the door opening points
and the wing chord mark. I scored small
sections of the line at a time, with a short length of metal saw and a flexible
ruler, making a groove to serve as a saw guide for final cutting. I did the same on the inner surface
considering the angle of the door cut line.
Then I passed the saw through both grooves and used them to guide the
saw and cut through the lines manually.
The groove on both surfaces makes the cut easy and tends to keep the saw
from deviating. I cut the bottom strake
shell entirely but stopped cutting short of the ends of the top to keep the
part attached to the strake until final installation. The door can be opened during the fitting
process and the attached bottom section supports the top shell in full until
permanent installation. I initially cut
the bottom strake shell at 90° (manual) but felt the strake was somewhat
interfering unnecessarily with the access to the cabin.
7. Foam Glassing
for Bulkheads/Baffles (1)
The manual does not
indicate placement of templates. I had
cut the foam in half and for that reason I came short on the longest
bulkhead. Should the foam piece had not
been cut, all would have fit. (Click for template positioning) On my setup,
the tip of the #3-4 template went into the other foam half. I decided to work on the 4’x4’ halves for
easier glassing and handling. I could
have cut the missing piece, glue it on the other side with some microslurry and
glass over them, to have enough length for the template. However, I had some spare foam around and
decided to use it. I glassed the foam
per the manual and used peel ply over them. I measured some of the templates
and found that most were bigger than necessary but some seemed to be shorter
than required to cover for the necessary angles between the parts. In this regard, I decided to make my own
templates in cardboard to reduce the building time and avoid the cumbersome
process described in the manual. Click for #8 on Related Projects/Ideas for a detailed explanation
of the process used.
8. Installation of
Bulkheads/Baffles (1) (2) (3) (4) (5) (6)
I cut the parts, trimmed
them, opened the mouse holes and sealed them by removing foam from the edges
and replacing it with micro. Using the
method above, I sequenced the installation so that I would not block the vision
of the parts as they were being temporarily or permanently installed. I cut and set the permanent parts, sometimes
with hot glue and some other permanently with micro as I made the cardboard
templates. Eventually, I glued all parts
with micro and let cure, at least until firm, before glassing the edges. When I
installed the inboard bulkhead permanently, I did not glue the baffle
section. I then was able to use the
adjacent bulkhead as a guide to cut it with a handsaw and remove it. For this I scored both sides of the bulkhead
with the aid of a ruler to guide the handsaw.
9. Strake-Beam
Reinforcement Bulkhead (1)
(2) (3)
I did not make this
bulkhead per the manual. I made a
cardboard template as well, with a horizontal cut to match the angle in the
carbon beam. I cut the parts from
pre-glassed foam and glued them to each other and in place with micro. This way, I did not have to glass and finish
the foam bulkhead in place. Once cured,
I reinforced the edges with a tape of glass.
10. Fuel Cap
Installation (1)
(2) (3) (4) (5) (6) (7)
I upgraded to metal fuel
caps. I located the hole based on the
position of the adjacent bulkheads and baffles.
I drew the circles with a compass and used a rotating saw to cut the
inner skin circle. I cut the outer skin
circle undersize with a Dremel grinding accessory and finished with a sanding
drum, using the compass circle line as a guide.
Finally, I sanded the inside surface of the outer skin with a #36
sanding disc, the inner skin and the foam to shape, making a groove in the foam
for better adhesion. I connected a
grounding cable to the base that exited behind the rear bulkhead and used micro
/ flox to install the gas cap base and fill the cavity. I prepared the BID between two plastic
pieces, drew a circle of appropriate size with the compass and cut it off with
a small knife. I placed the BID in place
and covered it with peel ply.
11. Fuel Sight
Gauge (1)
(2) (3)
I installed the fuel
sight gauge fittings per the manual, except that I opened the holes for the
fittings to fit tight on the cabin side.
I used a straight edge to align them with each other and glassed them in
the back. I cut the hose 1/8” shorter
than the exact required length to stretch it between the two fittings and
ensure a straight hose. I glued
MS21042-3 metal stop nuts inside all the 3/8" elbow sight gauge fittings
to keep the float balls I plan to use from entering the tanks.
12. Fuel Vent/Feed
Hard Points (1)
(2) (3) (4) (5) (6) (7) (8)
I determined the highest point
for the vent and the lowest for the feed line and opened the holes. I
installed the tapped hard points with Structural Epoxy (Aeropoxy) and
Cabosil; and let it set partially before glassing and finishing them with peel
ply. I used finger strainers for the
feed lines.
I liked the method
14. Sealing
Surfaces (1)
(2) (3) (4) (5) (6) (7)
Upon sanding the bottom
strake in preparation for sealing it, I noticed numerous holes would open in
the internal surface. I decided to fill
the holes with a mixture of EZ-Poxy and Cabosil. I then applied one coat of EZ-Poxy and peel
ply (left strake picture shown) followed by rough sanding before two coats of
Jeffco. I mixed small Jeffco batches of
180 ml in the regular mixing cups used for epoxy. This turned out to be a good amount that I
could apply before it would start to cure.
I bent a clothes hanger wire to place on my electric variable speed
drill and used as a mixing tool.
15. Top Strake
Installation (1)
(2) (3) (4) (5) (6) (7) (8) (9)
I noticed that the top
strake shell changed shape and/or shrunk during strake construction. I assume it was due to the time it took me to
finish the inside of this first strake and record high temperatures for several
days during this summer. I experienced
100°F days inside the garage. The
reason I know is because the top strake shell-fuselage gap was 1/16” inch at
the most in some areas and this increased to about 1/8” in those sections
between initial fitting and final installation.
I guess the changes always take place but this one is more noticeable
because of the large size of the part.
Hopefully, and if my theory is right, the temperature changes will not
be as dramatic for the second strake and I should take less time to complete. I placed small beads of modeling clay on top of
the cap strips and leading edge and fixed the top with clecos. This gave me an idea of the gap between these
and the top shell and the amount of Jeffco needed to install it. After trimming and matching the top strake, I
used clecos to set it in place and drew a leveled line on the leading edge as a
reference to grind it straight. It pays
off to carefully trim and adjust things as one builds the strake. This will help keep both sides symmetric and
minimize filling and sanding later.
Finally, I installed the top per the manual with assistance from my
brother Ed,
16. Tank Pressure
Test (1) (2)
I pressure tested the tank
and found a small leak in the door cut of the inboard leading edge. I attached the shop vacuum to the filler cap
access to create a vacuum, warmed up the leak area with a heat gun and started
applying droplets of EZPoxy on the area with the tip of a small mixing
stick. I also applied epoxy to the
nearby cleco hole and noticed it also sucked epoxy through it. I warmed up every so often and kept applying
epoxy until no more was being suck. I
let it cure for 12 hours and tested for pressure again. This time, it held pressure for 72
hours. I was happy at least with the
location of the leak because it made it very easy to fix. The factory recommends pressure testing after
all glassing of the bulkheads is completed.
Because I had flanges all around I did not intend to further glass the
tank. NOTE: I believe the leak came inside the glass tape
that ends in the area and probably toward the end, found its way through the
lower strake fiberglass wall. I am convinced that I caused the leak by
“not too careful” re-drilling of two nearby cleco holes that had been covered
during tape-glassing of the forward inboard bulkhead. I have learned to be more careful when drilling
anywhere around the tank, and also, and hopefully, to fix a leak. The actual installation of the top shell
turned out flawless but not without a lot of assistance.
To guide the cut, I had
scored the surface and made a groove (1) on the top and bottom
strake shells before permanently installing them. I used a short length of metal saw and a
straightedge. I completed the cut (2)
by hand for
better control, just like I did for the door-strake cut.
18. Filling
Strake/Fuselage Junction (1)
(2) (3) (4) (5) (6) (7) (8)
I decided to do this in
three steps for a cleaner process and for minimal use of material and
sanding. I used the dry Velocipoxy-microballoons
filler mix recommended by the factory. I
first filled the strake surface shaping the filler with a flexible 3” metal
spatula and the section attached to the door with a metal squeegee, as close to
final shape as possible, and removed the excess. I ran a razor blade through the door cut line
and left for final curing. I then sanded
it to shape with 60, 80, and 120 grit sandpaper, leaving it ready for primer. I protected the filled-sanded strake surface
with masking or duct tape and filled the fuselage-door surface, repeating the
curing–sanding process. I found that it
is better to fill the fuselage side before the strake side. Finally, I placed a radius of filler between
the two surfaces with a tongue depressor, let it cure and sanded it
smooth. It took me no more than 10
minutes of sanding for each one of the three steps.
19. Glassing /
Filling Strake’s Leading Edges
Working (1)
(1) (2) (3) (4) (5) (6) (7) (8)
After turning over the
airplane, I sanded and prepared the leading edge surfaces for tape-glassing (1). I placed some micro to even out the
top-bottom strake junction on the leading edge and serve as a smooth transition
for the tape-glass (2). I then used 2 BID over it and covered with peel
ply (3). After some light sanding, the leading edges
are now ready for filling. As usual,
there is not much filling or sanding to be done with the method above (4). I applied filler and shaped it with a plastic
squeegee. This is how it ended up
before sanding (5) (6). I then sanded with 80 grit sandpaper in
preparation for the primer (7) (8).
20. Glassing 
Inboard Space (1)
(2) (3) (4) (5)
Videos
2. Stippling with extended brush
I chose to install both rear
bulkheads before closing the strake.
Therefore, in order to glass the upper main spar cap-top strake junction,
I had to do it both from the cabin and from the outboard end of the
strake. The outboard space was easily
accessible and easy to do. The inboard
section was uncomfortable, but still easily accomplished with some
planning. I placed some cabo with a
spatula on the upper cap inside surface to avoid air bubbles when laying the
cloth, due to its uneven surface. I
filled the junction with flox (structural), just in case I couldn’t do a very
good glassing job. I wetted 2 BID over
plastic and placed oversize peel ply on top.
I hot-glued a brush between two pieces of wood and this assembly in turn
to a 3-foot wood ruler to make an “extended” brush. I then brushed some epoxy over the flox and
the adjacent strake’s inner skin where the lay-up would be placed. I ended up with an excess of epoxy as one
cannot control the amount when working at a distance. I removed the epoxy excess by laying paper
towel over the areas and stippling over them with the long brush. I peeled about two inches of the plastic from
underneath the cloth (lay-up) and duct-taped the edge of the plastic to the
edge of another 3-foot ruler. I then
rested the lay-up on top of the ruler, leaving the 2 inches of lay-up without
plastic, hanging past the end of the ruler.
I laid the lay-up overhang (without plastic) in place and by slowly
pulling the ruler it was resting on, I started removing the plastic from under
the it, laying the cloth in place in the process. The use of plastic underneath and peel ply on
top kept the lay-up from deforming and helped maintain its dimensions. l then used the long brush to push firmly in
place and eliminate possible air bubbles.
21. Outboard Strake
TRIAX Reinforcement (1)
(2) (3)
I did these per
the manual.
22. Outboard Wing
Bolt Access Cover (1)
(2)
I don’t like the
idea of using silicone to install any parts on the surface. I installed the outboard wing bolt access
covers with #4 ½ inch stainless steel sheet metal screws. I removed the screws and used a drop of
cyanoacrylate to harden the holes. If
necessary, I will drill an oversize hole, fill it with FLOX and reinstall the
covers with the same screws.
Left Strake (1)
(2) (3) (4) (5) (6) (7) (8) (9) (10)
(11)
(12) (13) (14) (15) (16) (17) (18) (19) (20)
(21)
(22) (23) (24) (25) (26) (27) (28) (29) (30)
One significant difference from the right strake was developing a method to close the strake without further reinforcement work (Click for # 11 on Related Projects / Ideas). I made flanges between the center main spar and the top strake so that I do not have to do any reinforcements or bulkhead installations after permanent installation of the top strake. Otherwise, I basically followed the same process as for the right strake above. This tank did not show up any dry leaks during the dry pressure testing.
LINK TO
CONSTRUCTION IMAGES ON THE OFFICIAL VELOCITY WEBSITE
THIS SECTION
IS UPDATED REGULARLY.
PLEASE REPORT
ANY MALFUNCTION OR BROKEN LINKS TO:
Jorge A. Bujanda / 2004