visitor Marlene B. wrote to ask for me to scan the articles for
the Pogo Formula I race and the Hot Canary Formula II racer, both
having appeared in the August 1971 American Aircraft Modeler. They
were presented as a matched pair even though each was created by
a separate designer, Bob Morse for the Pogo, and Bob Seiglekoff
for the Hot Canary.
A pair of unique and well-designed
racers for Formula I (Pogo
and Formula II/FAI NMPRA (Hot
) racing. These are just as competitive as the usual planes.
By Bob Morse
THE OWL RACER, designed by George Owl and
built by John Alford, was featured in the April 1971 AAM. This time
we present a Formula I racing version of this most unusual aircraft.
Its name is Pogo.
Pogo is unusual because of not using cheek cowls. Wing taper
is compromise between area and aspect ratio requirements. Stabilizer
is below wing turbulence.
Not having cheek cowls, engine is lost in fuselage. Exhaust
extension is essential.
The nose cowl treatment makes the difference. The designer departed
from the usual cheek cowls and employed a full-bodied wrap-around
cowling which actually will contribute thrust in flight. The miniature
racing version retains the full-bodied engine cowling shape of the
original and the only deviations from scale are those required to
meet the NMPRA Formula I racing rules.
The ship is very
stable in flight, showing no tendency to mush or stall in high-speed
pylon turns. It gets up on the step and grooves. If a good engine
is up front, it won't be second best! Construction
The fuselage is built on an inverted crutch, the lower half
built up completely on the 1/4 x 1/2" crutch members, including
the nose planking. When this has set up, remove the entire fuselage
bottom half, and then add the top formers and planking. Begin construction
with the ply frames, which are cut in separate bottom and top frames.
Cut the fuselage side panels and 1/32" ply doublers to the
phantom outline shown. Cutting them to the finished fuselage shape
will result in too shallow a fuselage. Assemble the sides by contact
cementing the doublers to the balsa side panels, being sure to make
a right hand and left hand. Next, glue the longitudinal and vertical
stiffeners in place. Cut in the cooling exit hole in the right hand
side plate and add the 1/32" ply air duct before fuselage assembly.
With all the frames cut to shape and the side assemblies
completed, begin the fuselage assembly by pinning the 1/4 x 1/2"
crutch members in place on the plan. Glue all frames in position
and, after the glue has set, cement the sides in place, leaving
about 1/32" of the crutch exposed. Next, add the 1/8 x 3/8" soft
balsa planking in the nose area. Then add the landing gear blocks
and the 1/16" cross grain bottom sheeting back to the rudder post.
This should complete the entire lower half of the fuselage. Let
this set for at least a day before picking if up.
add all top formers and proceed with the top planking. We planked
ours back to the rear cockpit frame and used 3/32" sheet for this.
Add the cowling nose blocks, rough the spinner area down to size
and then mount the engine and spinner in place to assist in positioning
the 1/16" ply spinner plate on the nose blocks. When this is done,
remove the engine and shape the nose blocks into the spinner plate.
We used the small drum sander on our Dremel tool, which did this
By now, the fuselage is just about completed
so, after a good smooth sanding job, paint on the first coat of
The flat bottom airfoil doesn't have a pat technical
explanation, but we have had a lot of experience with it. Jim Kirkland's
Shoestring of 1965 was the first Formula I ship to use it. Joe Foster
used it on his Rivets, National Champion in 1967 and 1968. We were
hooked on the wing section after flying two of Joe's Rivets and
decided to continue with it on our Ole Tiger. We've built up a lot
of flying time with this section and can recommend it without reservation,
both in high and low speed characteristics. Full elevator turns
can be made at high speed with no tendency to stall or mush and
lateral control is excellent in a fully flared landing attitude.
Another welcome characteristic is ease of building. The
first step is to pre-glue and sand the 1/16" medium balsa skins.
We recommend taping the 4" sheets together, then reversing the taped
assembly. Open each joint and lay a bead of coating resin in place.
Spread the skin out flat and wipe the excess from each joint. The
taped side will be the finished side and will require very little
sanding to finish.
Cut all ribs and put together the right
and left hand aileron bellcrank assemblies.
Pin the lower
skins to two building boards butted together at the wing center
line. With the center and two tip ribs in place, jack up the end
of one board until a straight edge just touches the top of each
of the ribs. This will provide all the dihedral in the bottom surface
and the top surface will be flat from tip to tip. Remove the ribs
and begin final assembly by gluing the lower 1/16 x 1/4" spruce
spars in place, adding the half-span 1/16 x 1/4" spruce doublers.
(Do not break the spars at the center line; let them run straight
through, tip to tip.) Add all the ribs and then the top spar with
its half-span doubler. Install the aileron bell cranks with their
pushrods in place. Addition of the rear spar, top skins, leading
edge and the sheet trailing edge will complete the basic wing structure.
Wing construction to this point takes four hours, and it
is basically finished. (Another strong point for this airfoil.)
All that remains is shaping the trailing edge, adding the tips and
sanding everything to shape. Add the fiberglass cloth strip all
around at the center section joint and the wing is ready for final
tail surfaces are rather straightforward and need no description.
At the leading edges, we added 1/16 x 1/4" spruce strips which seem
to stop the nicks and gouges caused by gravel thrown back by propwash.
Now to paint the Owl. We have used the coating resin system
for a long time now and recommend trying it. We use Starcast or
Francis Products Surfacing and Coating resins.
applying a brushed coat over the entire ship. After this has set
up, go over it lightly with coarse sandpaper to take the humps out.
Brush on a second coat, flowing it carefully, avoiding runs. If
this coat is added with care, the ship is ready for an attractive
color coat. However, for one of those fantastic elbow-power super
finishes, sand this coat well with 320 wet or dry paper, then spray
on a coat of DuPont gray lacquer primer. Then sand the primer coat
completely off the ship.
With very little effort, the surfaces
are, or should be, glass smooth and ready for the Hobbypoxy colors.
We masked and sprayed the basic red trim with Hobbypoxy Bright Red.
For the pin striping, we used a vinyl tape which seems to stick
with a vengeance. Forty feet of 3/32" wide taped (marked 1/16" wide)
was 57 cents at the local discount department store. The material
is called Trim-Brite pin striping tape and should be in auto supply
stores. Contact Spartan Plastics, P.O. Box 67, Holt, Mich. 48842,
for a local dealer. It's worth trying.
<click for larger version>
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Posted February 8, 2011