Here's a Flying "Broomstick"
The author demonstrates the position in which his Class "C" stick
A queerly-named craft, no doubt, but it has plenty contest cleaning-up
by C. A. Kukuvich
We believe this gull-wing stick has every characteristic of a
satisfactory contest model. The climb is very steep in a spiral-like
fashion. At the peak of the climb, the model rights itself and goes
into a long, flat glide.
Flights of 2 min., 30 sec., are common in "dead air" and are
accomplished without the help of risers. The best single flight
to date is 4 min. plus, which took place during a local contest,
and the model did not fly outside the airport bounds.
The drawings presented are self-explanatory and no difficulty
should be encountered in building this abbreviated "Flying Broomstick."
The first thing to do when making the shell is to soak for several
hours a 1/16" by 4" by 36" sheet of balsa in a bath tub filled with
about 3" of lukewarm water. Place the sheet at the bottom of the
tub and use water-filled glasses for weights.
After the stick is removed from its bath, wrap it around a form,
either wood or metal, with an outside diameter of approximately
7/8". Then bind cloth tape (not friction or adhesive) over the balsa
sheet to hold it in place while drying on the form. When the balsa
is thoroughly dry, remove it from the form and cut the balsa "shell"
into two pieces, one 30" long for the stick itself and the other
6" long for the wing mount saddle. Now cement the longer piece joint
the full length of the stick. When the joint has dried satisfactorily,
give the stick one coat of clear dope and then sand lightly. The
stick is now ready for covering with 2 1/2" wide strips of tissue
in a spiral-like fashion.
Make the 2 1/2" wide strips of tissue by cutting up a large sheet.
Apply the strips by doping and pressing firmly with your thumbs
until the full length of the stick is covered. This type of stick
construction is exceptionally strong and also quite light.
The stabilizer column mount and fin (which forms part of the
rudder along the bottom of the stick) is made from 1/8" by 1" by
36" sheet, as shown on Plate 1. After shaping the stabilizer mount,
cement two pieces of 1/16" by 1" by 2" balsa to the top of the mount
to form a seat for the stabilizer. This is shown in the detail in
Plate 1. Cement both the stabilizer mount and fin in their respective
places on the stick.
The nose and tail plugs are made from individual blocks 3/4"
by 1 1/4" by 1 1/2", which must be cut to shape to suit the stick.
Cement 1/4" pieces of balsa, which are of the same size as the inside
of the stick, to the backs of each plug, thus preventing them from
turning when the power strands are wound for flight.
Bend the rubber hooks from 1/16" diameter piano wire and cement
in place the one for the rear plug. The hook for the nose plug is
laid aside until it can be fitted onto the prop and bent to shape.
To make a better bearing, a piece of aluminum or brass tubing
1/16" I.D. should be inserted in the nose.
Cut ribs 1 to 19 from 1/16" soft balsa sheet. Then, spars numbered
29 and 30 are cut to shape from 1/8" sheet. Next, cut the trailing
edges 33 and 34 from 1/32" sheet balsa.
After having formed all the parts necessary for the wing, make
a full-size layout. When the layout has been completed, place a
sheet of wax paper over the drawing to prevent the structure from
sticking to it.
Lay the trailing edges, 33 and 34, in place and use a few pins
to hold them down. Then pin down the spars, numbered 29 and 30 and
cement all the ribs (with the exception of 1 and 7) in their respective
places. Before gluing the ribs to the spars, be sure to pull the
spars up into the rib cut-outs provided for them. Cement the 1/8"
sq. balsa strips in place to form the leading edges.
Like an exhausted bird, the "Flying Broomstick" comes to earth
after a flight of four minutes plus. This is excellent time, considering
that the flight was made without the aid of thermals.
The wing tips are made from a strip measuring 3/16" by 1" by
3" and are roughed out before cementing in place. Having allowed
the wing structure to dry thoroughly, remove the four sections from
the layout and add the proper amount of dihedral. Be sure to have
the same amount of dihedral on each wing half. Next, cement ribs
1 and 7 in place and add 1/32" sheet, re-enforcing at the joint
with liberal amounts of cement. When the dihedral joints are dry,
add 1/32" sheet balsa covering to the bottom of the wing between
ribs 1 and 7 in each half of the wing. Before applying the tissue
covering, finish off the wing tips and the rest of the structure
with fine sandpaper. The wing tips should continue, in a tapering
manner, the outline of rib 19.
When covering the wing use red tissue for the section from ribs
7 to 1, then cover the section from ribs 1 to 19. After covering
each half of the wing, top and bottom, pin down until dry to prevent
possible warping. Spray the top of section rib 1 to 7 and pin down
when drying to prevent warping. The bottom of section rib 1 to rib
7 need not be sprayed with water because when the tissue was applied
over the 1/32" sheet balsa, dope was used over the full surface.
Give the entire wing two thin coats of clear dope to protect
it from dampness and to give it more strength. The doping is done
by applying it to one surface at a time. First dope the top section
from rib 1 to rib 19 and pin down when drying. Then dope the bottom
of the same section and pin down. Now dope the top of section from
rib 1 to rib 7 and pin down to dry. Repeat this method of clear
doping to each wing half twice.
The wing mount is made by cementing together two pieces of 1/4"
balsa and then shaping it as shown on Plate 1. Now cement the mount
to the wing, using glue liberally. When the cement joint between
the wing and mount is dry, take the 6" piece of balsa "shell" and
cement it to the bottom of the wing mount. Be sure that when the
"shell" is opened and set over the stick the wing will line up properly.
Before laying the wing aside, and after all the wing mount cement
joints are dry, cover the 6" "shell" with tissue to give it flexibility.
Stabilizer and Rudder
Ribs 20 to 24 are made from the 1/16" soft balsa sheets. Cut
spar 31 from 1/8" sheet balsa and the trailing edge number 32 from
1/32" sheet. Next, make a full-size layout of the stabilizer by
scaling the drawing where dimensions are not given. Lay a sheet
of waxed paper over the layout and lay spar 31 in position. Place
the ribs in their respective positions and fit in trailing edge
Eighteen power strands housed within the shell of this graceful
craft give it plenty of power for high-altitude soaring.
After having lined up the ribs properly, cement in place and
add a 1/8" sq. balsa leading edge. The stabilizer tips are made
from 1/4" balsa and are roughed out before attachment.
When the tips are cemented in place and the whole structure is
dry, remove from the layout and cover the spars between ribs 20
with 1/32" sheet balsa. Then sand the whole structure with fine
sandpaper and finish off the tips to suit.
Gull wings and wide prop blades add to the efficiency of its
Cover the stabilizer with two pieces of red tissue (one for each
side of stabilizer) and water-spray. Be sure to pin down the whole
stabilizer after spraying. When the tissue is dry, give the surfaces
two coats of clear dope. Dope one side at a time and pin down on
the board. Repeat the doping process and the stabilizer is finished.
The first thing to do when making the rudder is to cut ribs 25
to 28 from 1/16" soft sheet balsa. Make a full-size layout of the
rudder by scaling off the drawing where dimensions are not given,
then cut out the necessary outline from 1/16" sheet balsa. Place
a sheet of waxed paper over the layout, set the ribs and the outline
in position, pin down, and cement at all points of contact.
After the bare structure has dried, remove it from the layout
and cover with red tissue, using the same procedure as in the case
of the stabilizer. Give the rudder one coat of clear dope by brushing
one side at a time.
When the rudder has been completed, cement it in place on the stabilizer
and fill in the gap between rib 28 and the top surface of the stabilizer
with scrap pieces of balsa. Finish by trimming off neatly. The corner
which is formed by the rudder and top surface of the stabilizer,
may be neatly filleted with scrap pieces of tissue.
Carving the Propeller
The propeller is a right-hand type and is made from a hard balsa
block, 1 1/4" by 2 1/2" by 16". Layout the block, as shown on the
drawing, and cut away the portions which are unnecessary to the
prop itself. Care should be exercised in carving the prop and all
bumps or hollows should be sanded out after carving. Remember that
the prop is what makes or breaks the model as a contest ship.
After the bumps and hollows have been removed, give the prop
several coats of clear dope and sand lightly between coats. Cover
the blades with silk or tissue, as desired.
Now enlarge the hole in the center of the prop to take either
aluminum or brass tubing. If free-wheeling is added, it is very
essential for the airscrew to turn smoothly on the shaft. However,
in the case of a folding prop, the important point is good alignment.
The Garami free wheeling is a reliable type, which has been tried
and tested many times.
Try the "Broomstick" under power, using a few turns to shirt
off with, and adding more revs on each successive flight.
The AMA Plans Service offers a
full-size version of many of the plans show here at a very reasonable cost. They
will scale the plans any size for you. It is always best to buy printed plans because
my scanner versions often have distortions that can cause parts to fit poorly. Purchasing
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