Speed 400 Cloudster
The Jim Adams plan has a sculptured cowl
that fairs into the back of a spinner as shown below.
After several concept considerations for
constructing a cowl, an approach finally immerged. Four 1/16" holes were
carefully hand drilled into the firewall as shown below.
Four 7/16" lengths of 1/16" piano wire
were cut and inserted into the holes in the firewall. The length of
these cowl alignment pins allow the pins to protrude out of the front face
of the firewall 3/16" to engage the rear face of the cowl sides.
Next, a 3" wide sheet of 3/16" medium
soft balsa sheet was cut to length for the cowl side shown below. A 3/16"
wide strip was cut from 1/64" plywood, which is also shown below.
The strip of plywood was glued to the
rear edge of the 3/16" balsa sheet. This protects the balsa edges from
getting all dented up. The two holes were marked to align with the cowl pins
and then drilled 3/8" deep. An aluminum tube with 1/16" I.D. was cut to
length and inserted into the hole as shown below.
A trial fit was performed to check the
alignment of the pins with the holes as shown below. Thank goodness, they
The aluminum tubes were removed and
then permanently CA's in place as shown below.
A strip of 1/16" plywood was drilled out
for the Speed 400 motor shaft. This plywood strip was forced down against
the front of the cowl sides and held down with a 3/32" wheel collar as shown
below. Even though the fuselage sides taper in at the front, the cowl sides
were positioned perpendicular to the firewall and CA's to the plywood strip.
In addition, as second balsa strip was added on the front of the cowl sides
to jig the cowl sides straight. Notice that a balsa brace was also added
between the cowl sides on the bottom back near the firewall to further hold
the cowl sides straight.
Once dry, the wheel collar was taken off
and the cowl frame was removed from the fuselage as shown below.
The cowl frame was turned over and this
picture taken to show the four lined holes to receive the four cowl
alignment pins. The reason the cowl sides are kept parallel is that any and
all balsa rectangular blocks can be easily glued to the inside faces of the
Before the cowl sides are blocked in on
top and bottom with balsa and the cowl carved to shape, a method for cowl
retention must first be designed. However, that will be the subject of
tomorrow's report. Work has stopped for the evening as the President's State
of the Union speech is coming on at 8:00 p.m. and will last until 10:00 p.m.
and Sue and I want to watch it in its