According to online sources, the OE-2 (aka the Bird Dog II) is a
redesigned version of the OE-1 with Cessna 180 wings and fuselage
modified for better visual observation. This R/C model by Bob Wischer
has a 54" wingspan and is powered by a .09 to .15 engine. The original,
having been built in the early 1960s, used an escapement for rudder-only
control. A modern micro or mini R/C system would easily permit 3-
or 4-channel operation with probably about the same all-up flying
weight. You could even convert it to electric power as is the popular
thing to do these days.
See the 4-view drawing of the
Cessna OE-2 from
the February 1957 edition of American Modeler, inked by
Walter M. Jefferies, Jr.
Winning R/C Scale: Cessna OE-2 Marine Observation Plane
At Wisconsin's Waukesha
County Airport model Cessnas turned out by the Wischer clan look
like the big USMC product.
OE-2 on left flew in Nats, one at
right is drawn.
Full size plans are by Hobby Helpers.
Designer-author-draftsman Bob Wischer
Mrs. Bob (Dolly) Wischer and Army's TL-19D Cessna.
Receiver in foam; OS throttle escapement; Bonner Varicomp
Fox with clapper throttle; tank; modified so all tubes
are on same side, is fastened by brass angles.
Wischer's OE-2 Cessna: Removable tail plug for winding
escapement rubber; 1/16" music wire torque rod end.
Ever watch the crowd gather when an R/C scale job is about to
be flown? There's something powerfully attractive about the sight
of a model of a real plane skimming lightly down the runway, taking
off and returning overhead looking every bit like the full size
aircraft. This kind of satisfaction is the scale modeler's reward
for the time and effort spent in careful building, finishing and
trimming. But his painstaking struggle is wasted if he chooses a
plane of such design that it can be flown only by an expert.
Any of the single-engine Cessnas will fly well as a model; the
Cessna A was a favorite for rubber power 30 years ago, and today's
descendants will perform as well in R/C. They have all the natural
stability of a well proportioned high-wing cabin monoplane, requiring
only a minimum of modification to produce a plane capable of flying
with the best of the specialized R/C types.
Our Cessna has had its 'stabilizer span increased by 2 inches
for greater stability, and the wing airfoil changed from NACA 2412
to 2415 to permit slower flight and help carry the R/C load. The
down thrust shown on the plan is identical with that of the real
plane; only side thrust had to be added. Dihedral was increased
only slightly. The force set-up evolved agrees closely with that
of a high performance R/C airplane. To be certain of a good flying
plane, the builder needs only to keep the weight down to a reasonable
figure by careful selection of balsa, especially behind the wing.
Like most scale models it is almost impossible to build one nose
heavy, therefore use the lightest balsa available in the tail section
and the heavy block construction in the nose.
The question of whether to apply a super-finish is the scale
builder's dilemma. Of the two OE-2 planes built by the writer, one
has a fancy finish with 14 coats built up into a thick layer of
smooth glossy dope. The other has a less velvety finish of 8 coats
but is 12 ounces lighter and consequently flies much better. Possibly
a compromise would be the answer since the lighter plane has a wing
loading of only 19 ounces per square foot. One consideration that
could influence the builder's decision is the ease of patching a
thin finish; and the often-flown lightweight plane is more vulnerable
to damage because it makes more landings. A common sight at contests
is the beautifully finished model which the owner is reluctant to
fly because he does not wish to damage the product of many hours
of labor and representing quite an outlay in cash. These models
often weigh so much that a high speed is required to get them airborne
and the end result is a mighty splat when they make contact with
the unyielding earth. For more fun flying and less work patching,
keep the weight down.
Contest judges are not always in agreement on the matter of finish.
Some will insist that a military plane like the OE-2 should have
a dull finish same as the prototype and will penalize the builder
who shows up with a gloss. Others are completely taken in by the
glitter and will give the prize to a plane so heavy with finish
that it will barely fly.
If the builder plans to enter his OE-2 in contests he will be
obliged to furnish proof of authenticity. By far the best source
in this case is his file of American Modelers where he will find
the well executed scale presentation by Walter Jefferies in the
February 1957 issue. This drawing was repeated in the 1957/1958
issue of Air Progress. A larger but less detailed drawing was obtained
from Cessna Aircraft Company of Wichita, Kansas. For photos of the
real plane see the Winter 1960 edition of Air Progress or write
to Aviation Photo Exchange, Box 75084, Los Angeles 5, California.
The writer's OE-2 has been entered in a number of contests and has
collected its share of prizes, including two first places.
Flying the OE-2 requires no special skill or experience as it
is a very forgiving airplane if properly balanced. Since the batteries
and receiver cannot be moved very far fore and aft, they are not
much help as ballast. Very likely the model will be slightly tail
heavy when balanced at the point shown on the plan, and some compensation
will have to be made in the form of weights added in the nose. When
the plane is viewed head-on a deep pocket will be seen just to the
right of the engine crankcase and this is a handy place to add weights.
About 2 ounces of solder is used in the writer's plane and this
is held in place by surrounding it with modeling clay. Weight should
be added to obtain a flat glide ending in a 2 wheel landing, not
a 3 point landing. If the nose comes up in the glide or if the tail
wheel touches in landing, add more weight to the nose.
With a .15 engine the OE-2 may be slightly overpowered, and first
flights should be with a rich mixture to help slow it down. Rudder
movement of 3/8" to 1/2" will produce turns that are not too steep.
Due to the low dihedral in the wing there is a tendency for the
OE-2 to continue turning after rudder is neutralized but this was
considered acceptable in view of the improvement in scale appearance.
Simply blip opposite rudder to stop the turn. Actually this type
of flying results in smooth turns since there is no jerking as there
would be in blipping around a turn. The receiver used is a Kraft
operating a compound escapement and a two position throttle escapement.
A clapper valve is employed over the venturi of the Fox .15 to give
two speed control. A new engine may overheat if run with the removable
cowl in place. Most flying is done with the cowl and wing struts
removed ... however, in a contest they must remain in place or the
flier risks disqualification.
Troublesome ground-looping tendencies are the main reason that some
R/C models will not make those desirable, long, straight take-off
runs. This could be caused by misalignment of the wheels or binding
between wheel and axle, but is more' likely to result from the wheels
being located too far forward relative to the plane's center of
gravity. Should this occur with the OE-2, a small balsa block can
be placed between the floor and the forward extension of the front
landing gear leg to force the wheels toward the rear. Do not carry
this too far as a nose-over could result, and also scale appearance
Construction data appears on the full size Hobby Helpers' plans
Cessna OE-1 Plans
Cessna OE-1 Plans
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 July 5, 2014