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 Seiglekoff
THE HOT CANARY is a really different
airplane. A biplane racer is unusual enough, but designer-builder
and flier Bill Warwick wanted to see the pylons as he banked into
the turns so he put the upper wing behind the pilot!
Lots of room in the engine compartment for easy, quick servicing.
Needle is quite handy.
Bottom wing leading edge notched to fit under aluminum landing
After seeing the Hot Canary at the 1970 Reno races, we felt the
urge to build a miniature pylon racing version. The design fits
both the FAI International racing rules and the AMA Formula II event.
Total surface area is 705 sq. in. (698 required for FAI). It is
an excellent flyer, but control surface movements must be minimized.
An eighth of an inch up and down on both the elevators and ailerons
should be more than sufficient for trial flights. Movements can
then be adjusted after trimming and altitude adjusting flights.
The bane of any fast pylon racer is that too much elevator
will induce a snap roll, and a t racing altitudes this is an immediate
disaster-a characteristic of any model turning pylons at over 100
mph. Consider the wing loading of a five-lb. plane at six or eight
g's with 600 sq. in. wing area. That's asking the wings to support
a 40-lb. weight (or 154 oz./sq. ft. wing loading)! Flying on the
safe side of the elevator travel is essential.
to believe, but the first prototype, with a plain wood finish, had
its wings an inch and a half farther aft than shown on the plans.
What a goofball-looking thing that was, but it flew, and fast. In
several match races against a competitive Formula I Ballerina, the
Hot Canary held its own.
Because of too much elevator travel,
the first prototype ended in a snap roll at about a ten-ft. altitude
in the No.2 pylon turn. The second prototype, with its wings moved
forward, appears far less sensitive in this respect, but it is still
important to keep all control throws down. Do not fly with a CG
aft of that shown on the plans.Construction
Building the Hot Canary poses no problem. The fuselage
is a square box with no "fancies." Begin with the fuselage side
assemblies, adding the ply doubler to the balsa sides with contact
cement. Then add the 1/4" sq. longerons and 1/8" x 1/4" uprights
with Titebond, making right- and left-hand panels. Lightly score
the ply doublers at the bend points (shown in the plan view) and,
with a straightedge over the scored line, gently crack the side
assemblies so that a sharp bend point results.
assembly by gluing the sides to the intermediate cabin area bulkheads.
Add several temporary diagonal braces top and bottom to keep things
square, then add the firewall, top and bottom sheeting, landing
gear mount, etc.
The 1/8" wing doublers should have the
wing hold-down block cutouts cut right through, serving as doublers
for the anchor blocks.
The wing and tail construction is
straightforward. Both the upper and lower wings are made from the
same foam cores, but are finished a little differently. Notch out
the cores and add the vertical grain blocks where the hold-down
screws go through. Add the trailing edge spar to each core and then
the 1/16" lower skin. The top wing should have enough lower skin
to reach the trailing edge; the lower wing stops at the spar.
On the top wing, fill in the trailing edge area with foam
or soft balsa. Then sand this down to the wing contour, leaving
a feather edge at the trailing edge. Add on the upper wing), the
balsa tips and finally the leading edges.
Finish the basic
undercoat on the fuselage and tail before the tail surfaces are
installed in the fuselage. At this point, it is a lot easier to
put on the two coats of surfacing resin and sand them.
this is done, place the elevator horn assembly, with its pushrod
hooked up, in the fuselage, then slide the stabilizer in place and
cement securely. Install the elevator onto the horn and hinges.
Then cement the vertical fin in position and install the rudder.
This method provides a neat tail end with only a rudder pushrod
hanging out in the wind.
resin is suggested as a basic undercoat for Hobbypoxy finish colors.
We prefer this system of finishing primarily because we are lazy
and like to get flying sooner. It involves one quickly brushed-on
coat of resin, lightly sanded after drying about two hours. A second
coat is flowed on carefully so that runs do not develop. After this
has set up in about two hours, it is ready to accept a color coat.
For a superb muscle-power finish, a third coat of DuPont gray lacquer
primer can be sprayed on. This is sanded off as completely as possible.
The K&B rear-rotor engine with its new fuel shut-off
racing venturi installed for NMPRA racing is shown, rather than
the barrel throttle required for FAI. However, there is room for
the throttle for FAI.
We flew the first ship with an inverted
engine and fixed cheek cowls; the second, side-mounted as shown
with a removable cheek cowl. We prefer the clear-running side mount,
but the inverted mount requires less work. Before any pylon turns
are tried, take the ship up quite high and, after everything is
trimmed for level flight, try a vertical full elevator turn. If
the elevator throw is correct, a smooth tight turn will result with
no sign of snapping. If it does snap, level out, land the ship and
cut down the throw. Conversely, if the turn is too wide, increase
the throw until full stick deflection gets the plane around quickly.
Hot Canary Plans
<click for larger
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
plans also help to support the operation of the Academy of Model
Aeronautics - the #1 advocate for model aviation throughout the world. If the AMA no longer has this plan on file, I
will be glad to send you my higher resolution version.
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Posted February 8, 2011