47 Model Aviation AUGUS T 2012 www.ModelAviation.com
Inverted flight is easy with the Hobo. Photo by Dave Russum.
mounts can be drilled for the engine
before the crutch is installed.)
Install the crutch and plywood F- 1
through F- 3 onto one fuselage
side. Use a 90º triangle to
make sure that all parts are
perpendicular to the fuselage
side. When the glue has dried,
Using the notches and tabs, the
parts snap into place. The basic
fuselage can be built in one day.
I recommend using 30-minute or
1-hour epoxy for installing the 1/32
doublers, engine mounts, and all
When the nose parts are dry, use a
centerline drawn on your table, or
a fuselage jig to align the fuselage
sides, and install the remaining balsa
formers. Do not remove the building
tabs at this time.
The Hobo’s wing can be assembled in
one evening. Laser-cut ribs are available
from Blue Sky Models. Splice the spars
and TEs as shown on the plans. Mark
the rib locations on the spars and TE.
Place the ribs onto the 1/4-inch spars,
but do not glue them into place. Use a
long straightedge at the rear of the rib
jigging feet to make sure the wing’s TE
Using thin CA, attach each rib to the
lower TE and the main spars. Use cotton
swabs to wipe away excess glue before it
Check the alignment and glue the LE
and main 1/4-inch spars in place along
with the lower 3/16-inch center spar and
the top TE sheet.
Use aliphatic glue and masking tape
to install the 1/4-inch TE cap. You can
now turn the wing over and install the
3/32-inch center section sheeting. Don’t
remove the rib jigging feet at this time.
The 1/4-inch spars will be flush with
the center section sheeting. I advise
placing light weights over the ribs
during assembly to ensure that the wing
remains straight. Use care installing the
half ribs. They are delicate until glued
You can choose to use internal or
external controls, which is a unique
feature of the Hobo. The external
controls will allow easy control-ratio
adjustment to achieve competition-type
maneuvers or outlandish fun maneuvers.
The inner center rib must be trimmed
slightly to allow you to install the
bellcrank mount on top of the 1/4-inch
and 3/16-inch lower spars. Install the
upper center section’s 3/16-inch spar and
complete the bellcrank to flap controls
and install the upper center section
Install the inboard 1/8-inch light
plywood wingtip rib and slider. Then
install a 4-40 blind nut on the inside
of the outboard 1/8-inch light plywood
wingtip. I suggest permanently installing
approximately 1/2 ounce of weight
inside the outboard wingtip.
Final weight can be added externally
using bolt-on weights that are available
from Sig Manufacturing or Brodak
Manufacturing. Trim and sand the LE
and TE caps to shape and complete the
If you are using external controls,
the fuselage can slide onto the wing.
If you have internal controls you can
place the fuselage upside down on the
building tabs and cut out a section of
the fuselage to install the wing and then
replace the cutout sections.
If you cut the fuselage, make sure that
you install internal 1/32-inch plywood
doublers across the slice. These can be
made from scrap material and should
extend 1 inch at each side of the joint.
I suggest that you make wingtip jigs to
help ensure that the wing is installed
square into the fuselage.
Use either a 1/8-inch wire landing gear
installed with J-bolts or .093 aluminum
gear. The forward fuselage side view
shows this installation. Several suppliers
have landing gear that will work well.
A 1/8-inch plywood plate is made, and
two sets of blind nuts can be installed so