How to Add Engine
Details to the H&M Viper GFK Hull
Ralph von Eppinghoven
Metro Marine Modelers
The Hydro & Marine Viper GFK hull is a model of a modern, piston powered,
hydroplane. It is easy to add simulated “velocity stacks” to the hatch to
replicate engine details to give the hull a realistic look. This article
shows how to make these “stacks” and install them in the hatch to make a
scale, piston powered, Fast Electric hydroplane hull. Photo 1 shows the
finished engine details on the hatch.
Photo 1: The finished detailed
hatch and hull
following materials are required to add the engine details to the hatch.
minimum thickness aircraft plywood
diameter aluminium tubing
diameter wood dowel
Medium thickness CA Glue
minute epoxy glue
grit sand paper
2: MAKING THE
most piston powered hydroplanes use twelve cylinder engines, twelve
simulated velocity stacks were added to the hydroplane model. To make the
stacks, simply cut the 9/32” aluminium tube into twelve, 5/8” long pieces.
The length is not critical since the stacks will be trimmed to the desired
length after they are glued into the base.
Once the stacks are cut to
length, it is desirable to widen the tops of the stacks to simulate the
flared opening on real velocity stacks. The ends of the aluminium tubes are
flared by gently tapping the cone-shaped dowel into the end of each tube.
The dowel tool was made by sanding and filing a cone shape end to the wood
dowel. Photo 2 shows the dowel tool and cut aluminium pieces.
Photo 2: 9/32” aluminium tubing pieces and the
used to widen the ends
Photo 3: Rectangular plywood base with
holes drilled for the tubes
3: MAKING THE
stacks are held in place by gluing them into a thin plywood base. Before
making the base, decide on the configuration of the stacks in the hatch.
This example shows the stacks grouped in two clusters of six, and the stacks
are in-line with each other. Once the configuration has been finalised, cut
a 1-1/4” X 3-1/2” rectangle out of thin plywood. The minimum required
thickness for the plywood is 5/32”. Mark the stack layout on the wood base
and drill the twelve holes as shown in Photo 3. Test fit the aluminium
tubing to make sure the stacks line up as desired. Do not glue the tubes
into the base yet – this will done after the tube height is finalised in
the stacks have been placed (not glued) in the base, it is possible to
determine the required hatch openings to accommodate the stacks. In this
example, each hatch opening is 7/8” X 1-3/8” and there is a ¼” gap between
the openings. Mark the dimensions to be cut on the hatch and cut the
openings using a cutting wheel and dremel tool. To prevent scratching the
hatch, cover the area to be cut using low tack masking tape. The tape also
makes it easy to mark the openings on the hatch. Photo 4 shows the finished
openings cut in the hatch.
Photo 4: Hatch openings to
Photo 5: Stacks in painted
base after being glued to desired height.
fit the stacks and base in the hatch opening to ensure the stacks will fit
correctly and that there are no gaps between the base and openings. Remove
all the stacks from the base, and prime and paint the base the desired
colour. In this example, the base was primed and painted black with Krylon
spray paints. After the base has been painted, re-assemble the stacks and
test fit the base and stacks in the hatch. Adjust the stack heights so they
protrude through the hatch to the desired height. Make sure the tops of the
stacks are level. Glue the stacks in the base to the desired height using
medium CA glue. Trim the excess the aluminium tube from the underside of the
base using a cutting wheel and dremel tool. Photo 5 shows the finished
stacks and base. A coat of Krylon clear coat was applied to the base and
stacks to protect the finish. The next step is to sand the bottom of the
wood base so that it is flat and smooth. Cut a rectangle, the same size as
the wood base, out of .030” sheet styrene and glue it to the underside of
the base. Make sure the sheet is fully seated on the wood since this will
prevent water from entering the hull through the stacks. Photo 6 shows the
sheet styrene glued onto the wood base.
THE BASE IN THE HATCH
fit the finished base and stacks in the hatch and tack glue the base in
place. Apply a bead of epoxy glue around the entire edge of the wood base to
prevent water from entering the hull around the base. Check to ensure that
all gaps between the base and hatch are sealed with the epoxy to ensure a
waterproof joint. Photo 6 shows the base glued into the hatch.
Finished base and stacks
into the hatch (underside)
Stacks installed in hatch
shows the completed hatch with the engine details. The simulated engine
details really highlight that this model replicates a piston powered
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