|
Construction and Set-Up of a “Cut-Down” Fine Design
Marine Turbo Vee 12-Cell, Mono-Hull
By
Ralph von Eppinghoven
Metro Marine Modelers
Toronto, Canada
Photo
1: Finished FDM Turbo Vee with modified hull, decals, and scale drivers
SECTION 1: BOAT DESCRIPTION
1.1
Boat Specifications:
-
Hull:
FDM Turbo-Vee 29” ABS mono-hull
-
Motor: FDM Cordite 775 11 Turn Ferrite (commonly called 8.4 v Speed 700
BB)
-
Hardware: Fine Design c/w trim tabs and turn fins
-
Shaft: Octura 0.130” flex and Octura Flex hex
-
Propeller: Octura X645
-
Speed
Control: Astroflight 212D (using BEC)
-
Radio
System: Hitec Lynx FM
-
Power: 12 Sanyo RC 2400s in two 6-cell pack configuration
1.2
Project Description:
Fine Design Marine
(www.finedesignrc.com)
has recently started supplying complete, mono-hull boat kits that include
hull, running hardware, motor, motor mount, flex shaft, coupler, pushrod and
all fasteners required to put a competitive, 12-cell, “fast electric” R.C.
boat on the pond. The FDM kit is based on the Graupner Electro Vee ABS hull
which has a proven history as a winner. This article describes the
construction and set-up of the FDM kit, which is called the “Turbo Vee”.
It should be noted that the standard Electro Vee is an excellent hull “as
is.” This article covers a “cut down” version of this hull that also
includes scale drivers and cockpit. These modifications are optional and are
only recommended for experienced modelers.
SECTION 2: HULL CONSTRUCTION
2.1
Cutting Down the Hull to Reduce the Hull Height:
A number of fast electric (FE) racers have had success cutting down the hull
in order to reduce its height by approximately 1” and thereby improve its
handling by lowering the boat’s center of gravity. To cut down the hull by
1”, lay the hull upside down on a flat surface and trace a line 1” up from
the surface to mark the cut line. A simple way to do this is place a dry
erase marker on a ¾” block and trace a line around the perimeter of the
hull. Once the line is marked, simply cut along the line using heavy-duty
scissors. Sand the edge smooth using 120 grit sandpaper and a sanding block.
Once the hull has been reduced in height, it will be necessary to modify the
deck to fit the hull since the upper hull dimensions have been reduced. It
will be necessary to reduce the length and width of the deck as shown in
Photo 2. The length of the deck was reduced approximately 1.5” by removing
this amount of material from each side of the upper deck. The width of the
deck was reduced by ¾” in two ways: 1) removing ¾” from the back edge of the
upper deck and 2) removing a long thin wedge of material from the bow
portion (Photo 2 has the bow deck wedge removed and the bow deck re-glued).
In all cases, careful test fitting of the hull and the deck pieces will be
required to ensure correct cutting and dimensioning since all the dimensions
vary, depending upon the amount of hull material that is “cut down.”
Photo 2: Hull reduced 1” in height, and the modified deck before re-gluing
The bow
deck can be reduced in width by cutting the deck down the middle almost to
the tip of the bow (leave ¼” attached at the bow). Place the cut deck
section on the cut down hull, and squeeze the deck down to fit the hull and
mark the overlap with a marker. The wedge should be approximately ¾” wide at
the hatch opening and taper down to a point just before the tip of the bow.
Cut the overlap wedge as marked and re-glue the bow deck using CA and
“kicker.” Place the narrowed bow section of the deck on the hull and place
the two stern portions of the deck on the hull to test fit the pieces. The
stern sections will overlap each other and the bow section. Mark and cut the
overlap. As mentioned above, the length of each stern section will be
reduced by approximately 1.5” while the width will be reduced by about ¾”
overall. Once all the overlap cuts have been made, carefully “tack” the
edges of the deck sections using CA glue. Test fit the deck and hull again
to make sure that the fit is satisfactory. The hull edges must fit snugly
into the lip of the deck edge. Once the fit is adequate, fully glue the
pieces with CA and strengthen all the deck joints by gluing a ½” strip of
ABS on the underside of the deck seams. There should be enough surplus ABS
material from trimming the original hull and deck to make the ½” strips.
Once the deck has been modified to fit the hull, it is necessary to reduce
the width and length of the hatch accordingly. This is done by test fitting
the hatch on the deck opening. In this case, the hatch width was reduced ¾”
by removing ¾” of material down the centre line and re-gluing the hatch
halves together. The length was reduced by removing approximately 1” of
material from the front (bow) end of the hatch. The hatch was also reduced
in height by cutting down the lower edges such that the height was reduced
to ¼”. Again, a ½” ABS strip was glued on the center seam for strengthening
of the joint. Photo 3 shows the underside of the finished deck and hatch.
Note the wood trim around the deck opening for additional strength and
support. The hatch ridge around the opening on the deck has also been cut
down to allow the modified hatch to fit flush on the deck (see photo 2).
Photo 3: Underside of finished deck and hatch
In
order to properly install the running hardware, it is necessary to
strengthen the transom by gluing a ¼” sheet of light plywood inside the hull
transom. The finished transom doubler is shown in place in Photo 4.
Photo 4: Installed ¼” plywood transom doubler and motor mount
Once
the transom doubler is glued in place, the hull and deck can be glued
together with CA glue. It is easier to do this if the deck and hull are
temporarily taped together. The tape should hold the hull sides tightly
against the edges of the deck. Using medium CA sparingly, tack glue the hull
and deck in a few locations starting from the transom and working forward on
both sides Check to make sure no hull or deck twists have been introduced.
Once the hull and deck have been tacked in place, simply run a bead of
medium CA around the entire perimeter of the hull/deck joint while the boat
is turned upside down.
The motor is installed near the stern of the boat and at a downward angle to
minimize the flex shaft length and bending. In order to support the motor at
an angle, a small wooden wedge is glued into the hull and the motor mount is
glued to the wedge as shown in Photo 4. The bow end of the wooden wedge and
motor mount should be glued 5-3/4” from the transom. To provide additional
support to the motor mount and the hull bottom, a flat triangle of 3/16”
plywood is glued it to the wooden wedge and hull bottom as shown in Photo 5.
Photo 5 also shows the final configuration of the stuffing tube, teflon
liner and flex shaft.
Photo 5: Inside of hull showing installed motor mount
SECTION 3: RUNNING HARDWARE INSTALLATION
3.1
Bracket, Strut and Rudder Installation:
The bracket, strut and rudder are installed as shown in Photos 6 and 7.
Photo 6: Hardware installed on transom - top view and side view
As
shown in Photo 7, the rudder base should be centered 1-5/8” to the right of
the center line of the strut bracket, and the bottom edge of the rudder base
should be 5/8” above the bottom edge of the transom, when measured in a
straight line directly below the rudder base center line.
The depth of the rudder can be adjusted by placing 3/16” Du-Bro brass
collars between the rudder post and the control arm as desired. Adding one
such collar places the rudder at the correct depth for proper clockwise and
counter-clockwise turning for racing on an M-course.
Photo 7: Running hardware installed on transom
3.2
Trim Tab and Turn Fin Installation:
The two trim tabs are screwed to the transom, flush with the hull bottom,
and are placed such that the inside edge of the trim tab is 5/8” up from the
centre line of the transom. In this position, the outer edge of the trim tab
should be approximately lined up with the outermost strake on the underside
of the hull. The two turn fins are screwed to the transom, atop the trim
tabs, and are installed in line with the outermost strake under the hull
instead of the outer edge of the hull so that they: a) enter the water
earlier in the turn and hold the corner better, and b) are perpendicular to
the vee of the hull. Photo 7 shows the finished installation of the trim
tabs and turn fins.
SECTION 4: INTERIOR COMPONENT LAYOUT
4.1
Layout:
The batteries, ESC, servo and receiver are placed in the hull as shown in
Photo 8.This layout results in the Centre of Gravity (C of G) of the boat
being approximately 7-3/4” from the transom. This is 29% of the hull length
and typical for mono-hulls.
Photo 8: Interior Layout
4.2
Servo Installation:
The servo is installed near the transom, and the servo arm is in line with
the rudder arm so that a simple, straight pushrod can be used to connect the
servo arm to the rudder arm. Photo 9 shows the servo installed in the hull.
The servo is screwed into two, small, wooden blocks that are glued into the
hull.
Photo 9: Servo and pushrod installed in hull
The
motor will heat up during high speed running with the X645 propeller, so it
is recommended to use a cooling coil on the motor as shown in Photo 8.
SECTION 5: SET UP AND RUNNING
5.1
Balance and Trim:
The boat, as configured in this example, will have a Centre of Gravity (C of
G) of approximately 7-3/4” measured from the back of the transom. This is
the balance point that results in good speed and handling for this boat. The
C of G can be adjusted easily by moving the battery packs forward or
backward in the hull. In this case, this C of G was obtained with the
batteries positioned so they were just touching the motor mount as shown in
Photo 8.
This boat is simple to set up and very few adjustments are required to “dial
it in”. The trim tabs are left in the original 90 degree, or neutral
position. The strut can be lowered slightly to get the hull a bit more out
of the water. A slight positive angle to the strut bullet (back of prop is
higher than front of prop) helps to keep the bow slightly up.
As mentioned earlier, the rudder depth can be adjusted for optimum turning
in both directions. If only right turns are required, the rudder should be
run shallower so as to minimize drag. A deeper rudder ensures no spin outs
when turning left as well.
5.2
Speed and Run Time
This boat has been measured at 25 mph (using a Garmain e-Trek GPS) when set
up as described and using an Octura X645 propeller. The run time can exceed
4-1/2 minutes with 2400 mAHhr batteries but it is strongly recommended that
the run time not exceed 3 minutes with the X645 prop due to motor heat. If
longer runtimes are desired , then a X442 prop should be used. The speed
will be decreased to about 20-22 mph with this prop but it is great for
sport running and will provide 5 minute run times.
SECTION 6: HATCH DETAILING AND PAINTING (Optional)
This
section deals entirely with painting and detailed modelling techniques to
add driver figures and a cockpit to the hatch. Some modelling experience is
required for this work since the pieces will all be built from “scratch”.
These details are simply to provide a scale, offshore, race boat appearance
to the model.
6.1
Steering Wheel and Throttle Lever:
The two figures, the throttleman on the left side of the cockpit and the
driver on the right side, will be grasping a throttle control lever and
steering wheel, respectively, as shown in Photo 10. Prior to cutting and
assembling the figures, it is necessary to build a throttle lever and
steering wheel. The steering wheel is simply taken from a 1/10 scale toy car
(any suitable steering wheel will do) and glued to a small length of brass
tubing. The throttle lever is simply a “T” shaped wire glued to a small
block of balsa wood.
6.2
Driver and Throttleman Figures:
The driver and throttleman figures are Mattel Hot Wheels “Stunt Cycle”
figures that were cut apart and re-glued in the correct position. Any toy
figure will do, but the Mattel figures are quite good since they are
approximately the correct scale; they are made of soft plastic which is easy
to cut and glue; and the legs can easily be removed, leaving a screw hole
for the torso to be attached to the hatch lid.
6.3
Instrument Panel:
The instrument panel is simply a thin strip of ABS plastic that has 7/32”
holes spaced equally across its length to simulate instrument bezels and
paper instrument faces are glued in place behind the panel. The instrument
panel can be seen in Photo 10.
Photo 10: Finished driver, throttleman and instrument panel
6.4
Painting and Decals:
The Turbo Vee hull is made of high quality, polished, ABS plastic and does
not require painting. If desired, the hull can be painted to improve its
appearance. Care must be taken when selecting the paint since many common
aerosol paints will harm the plastic. It is recommended to use KRYLON brand
paint since it is safe for all plastics. Wash the hull with a mild
detergent, such as diluted dishwashing liquid, in order to remove any
residual materials from the hull. Next, lightly sand the hull with very fine
sandpaper (1,000 grit is suitable) to give the paint a good surface to stick
to. Spray on a suitable sandable primer and let this coat dry fully (usually
24 hours) and then spray on the final colour coats.
It is
quite easy to apply decals and automotive pinstriping to add interesting
graphics to the boat. In this example, Auto Graphics brand decals, with the
“Bad to the Bone” racing team logo, and Team Fine Design decals have been
applied to the hull.
In
order to protect the decals, stripes and paint and to provide a glossy shine
to the finished boat, a final layer of “clear coat” paint was applied to the
entire hull surface. Photo 11 shows the finished FDM Turbo-Vee with all of
the detailing.
Photo 11: Exterior views of the painted FDM Turbo Vee
|
