Lockheed Sirius Article & Plans
April 1973 American Aircraft Modeler
Here is the article and plans for
the Lockheed Sirius that I electronically scanned from my purchased copy of the April 1973 American Aircraft
Modeler magazine. You might be able to scale up the image below if you cannot find suitable plans for sale. Plans
for this fine model were drawn by Mr. Maurice F. Philips. All copyrights (if any) are hereby acknowledged.
[Table of Contents]|
Aircraft modeling has undergone significant
changes over the decades - both in technology and preferences. Magazines like American Aircraft Modeler, and American
Modeler before that, were the best venues for capturing snapshots of the status quo of the day. Still, many things never
change, so much of the old content is relevant to today's modeler.
Whether you are here to wax nostalgic, or are
just interested in learning history, hopefully you will find what you are seeking. As time permits, I will be glad to
scan articles for you. All copyrights (if any) are hereby acknowledged.
There were actually two separate articles, one that covered the history of the
Lockheed Sirius, written by Patricia T.
Groves, and the other this construction article for a scale R/C version.
Lockheed Sirius Article & Plans
Well-detailed and perfect
scale RC version of the Lindbergh inspired Lockheed design uses foam wings and a glass fuselage. A docile flyer,
MAURICE F. PHILIPS
The search for a suitable model to scale and to construct gets more difficult
as modelers continually dig through the files of civilian and military aircraft. It was surprising to find that
the Sirius hasn't recently been built. Many older modelers remember the famous plane that Lindbergh used to map
out some of Pan Am's early airways. Admiration for the model of this grand old aircraft of the golden era was
expressed by many of the spectators at the '72 Chicago Nats. Several mentioned that the model flew just like the
full-sized plane they had seen fly in the 30s. It was pleasantly surprising to find spectator appeal so high.
There were two friends that influenced my decision to build the Lockheed Sirius - Monty Groves and Bob Palmer.
Both, although separated geographically, have a common interest in Lockheed aircraft.
The Sirius model
results from the combined unique talents of the three of us. Monty and his wife Patty have researched Lockheed
aircraft for years and has a large file of photographs and technical data to support their documentation. Bob
Palmer, a professional modeler, has produced several fiberglass fuselage kits of very high quality. This airplane
was a natural for him due to his ability to reproduce the scale details in epoxy. In making the decision to
combine our efforts, it was decided that fiberglass would more closely represent the original plywood mold
construction than conventional balsa planking over formers. My contribution was to do the scaling, drawing, and
inking as well as to design the construction characteristic to fiberglass and polystyrene foam.
The model can be flown in SuperScale or in Stand-off Scale contests. The Sirius does not have either retractable
landing gear or flaps, thus giving other models a slight advantage in regular AMA or FAI contests. However' its
ability to perform contest stunt maneuvers does tend to be equalizing. Almost every author attests to his model's
ability to fly on a string. A detailed description of the first few flights will follow later in the text.
Lockheed Sirius R/C Model
Fiberglass wheel pants come with the fuselages too and are quite durable. Note plywood fill-in between inner
landing gear struts.
Cowl alignment jig taped in place.
Below: Fiberglass cowl has tabs epoxied inside for attachment to firewall.
In building the fuselage, a Dremel tool IS used to cut out the cockpit
openings and the openings for the horizontal stabilizer of the fuselage. The tail cone should be cut off using the
minimum cerf. When fitting the stab, it will be necessary to file the opening slightly. The fuselage tail cone
will be epoxied back after the stab is installed. Mount the radial engine mount using blind nuts. Note that
dimples indicate the centerline.
Do not tap the mount for the engine until the engine is positioned at 0 degrees side thrust and 0 degrees
down thrust. A propeller was used to assist in the measurement. Measure the drawing to see how far the thrust
washer protrudes past the cowl. Don't forget the spinner back plate. Construct the plywood brackets that hold the
cowl to the fuselage. Use an extra strong ep'0xy such as 3-M Structural Adhesive. With an alignment jig position
the cowl while allowing the epoxy to set.
After the brackets have been attached to the cowl, fuel-proof
them by coating with Hobbypoxy II glue. The battery and fuel tank location worked out well on my model. Cut out
two windshields using the patterns. A strong material can be obtained by removing the copper from a thin
fiberglass circuit board .030 inches thick for the windshield frames. Several jigsaw blades will be dulled cutting
them out. Epoxy them in place with the 3-M epoxy. A wet finger will form a fillet nicely. Set the fuselage aside
and return to it after completing the rudder, elevator and stab.
Shape the ribs of 'the horizontal
stabilizer as shown. When applying the sheeting, be cautious not to apply a warp. Fit the completed stab into the
fuselage by filing the fiberglass and sanding the wood.
Select soft balsa for the elevators and shape with
a razor plane. Install the horn and hinges matching them to the stab. Epoxy the stab in place. Install the
elevator Gold-N-Rod at this time. A music wire through nylon tubing will possibly be less prone to change trim due
to heat (if you are worried .about that sort of thing).
Construct the rudder using the same techniques as for the elevator. After hinging the rudder to the fin and
installing the Gold-N-Rod, epoxy the tail cone back on to the fuselage. A good filler for the joint is common
body-fender fiberglass epoxy. It can be carved in the leather stage and sanded when hard.
basic construction of the fuselage including the tail skid, servo tray, hardwood wing hold-down blocks, and servo
installation. Use Hobbypoxy II glue to secure parts to the epoxy fuselage. Micro balloons or Cavasill may be added
to the glue when a thicker consistency is required.
Cut the three sections of the wing using the airfoils
that are shown on the drawing. Deduct the skin thickness when making the templates for the hot wire cutter. Wrap a
two-in. wide piece of four oz. glass cloth around the sheeted wing for a dihedral brace. Push the cloth against
the wood with a roll of toilet paper absorbing excess resin from the glass cloth. Feather the edges with garnet
Prior to the sheeting, install the aileron horns and linkage system. The aileron movement should be
not more than 3/8" up and 3/8" down.
When making balsa wing skins use resin to join together the skin sheets. A thin strip of silkspan doped
over the inner joint will prevent its raising after painting. Use a good contact cement for joining the skin to
the polystyrene foam. 3-M No. 77 is very good, but be careful to allow the thinners to evaporate before attaching
the skin or foam will melt a bit. The hardwood landing gear blocks worked very satisfactorily, but the plywood
plate backing the shock absorber pivot failed to support rough landings. A proposed modification will be to insert
a piece of No. G-Pad under the pivot to absorb the shock override. In general, the wing is straightforward
Landing gear - The aluminum brackets can easily be cut from bar stock with a hack
saw. With a power drill and file, the bracket is completed in short time. Bend the 3/16" and 5/32" dia. music wire
landing gears to exactly match the drawing (see front view for front strut).
The fiberglass wheel pants
were not available for the prototype, therefore the first set was formed from balsa. Three pieces of wood were
sandwiched and carved to shape. Plywood bearings were used for the axles.
Epoxy Gel-Cote, unlike
polyester, does seem to have a few pinholes. After cleansing the fuselage with acetone, spray the exterior with
Dupont grey primer. Mix a small amount of epoxy body filler and push through the holes from the inside of the
fuselage with your finger. After it hardens, sand with 280 wet and dry sandpaper. Small holes may be filled from
the exterior with thick primer available from the auto parts stores. It may be necessary to reo peat this
procedure until all the holes are filled.
Surprising as it may seem, all the wooden surfaces are covered
with fiber-glass cloth and resin. This is an exceptionally light finishing method if done properly. Purchase the
following materials: K&B 1/2 oz. glass cloth, Francis Products surfacing resin, single-edge razor blades, a roll
of toilet tissue. Cut a piece of the cloth slightly larger than the surface to be covered. Using a stiff brush,
apply the resin over the cloth on the balsa surface. Roll out the toilet tissue over the cloth absorbing the
resin. Tear off the end and peel the saturated paper away from the glass cloth. Be careful not to pull the cloth
away from the wood. Trim the cloth after the resin has hardened, sand slightly, and apply another full coat of
surfacing resin. After the resin has dried, scrape the surface with a sinqle-edqe razor blade as far as possible
without going through the cloth. Slightly sand the surface with varying degrees of garnet sandpaper. A coat of
auto primer will show any defects to be filled.
The drawing shows the CG at 25%, although 32% is
satisfactory. With the short nose moment, the difference required approximately six more ounces of lead in the
nose. My model used about 14 oz. of lead mounted under the engine mount and in the cowl. The Williams Bros. dummy
engine was cut up so badly that the weight was negligible.
Hobbypoxy was used to paint the model, The wing,
rudder, fin, stab, and elevators were orange while the fuselage, cowl, wheel pants and fairings were black.
Lindbergh's plane had gold trim on the cowl and fuselage bordered with red pin striping. Gold dope can be sprayed
over the Hobbypoxy if the spray is mist-like. A heavy coat will cause the Hobbypoxy to blister and peel. Be very
careful in removing the tape from the fuselage, as there is a tendency to peel the paint away from the epoxy
fuselage. This can turn a mild tempered modeler irate, raving and swearing.
The first flying attempt was a
disaster followed by many successful, pleasing flights. Dr. Les Stephenson, Ralph Young and I decided to give the
Sirius its maiden flight at the Hollister airport. A warm 102 degree day was chosen for the test. The Enya II
engine and Perry carburetor performed flawlessly, idling at 2700 rpm for as long as required.
picked up with the first burst of power and the model made a sudden turn. to the left. The correction with my left
thumb must have accidentally applied elevator and it cartwheeled. The nylon bolts sheared from the cowl mounts and
the wing tips were scuffed. Other than a few small cracks, the damage was minor. Two adjustments were made. The
elevator throw was decreased and full right rudder trim was used for takeoff. Once airborne, the trim was removed.
This countered the torque, although there was a tendency to steer to the right.
The next five flights were
made at the '72 Chicago Nats. where it flew even better than I had expected. The roll is slow and in loop it
tracked perfectly. The landings were easy to control which is probably due to the thick Clark Y airfoil. The
Gold-N-Rods tended to change trim in the black fuselage when the temperature rose. The next model will probably
have music wire running through the nylon tubing.
When the. engine was "honking," I found the nine-lb.
wonder did not perform at at all like a heavy model. It was an easy, fun to fly model. The director of the
airshow, at the '72 Nats, asked me to fly it for the spectators. Many of the people showed their admiration by
thanking me for taking part in the exhibition. This was personally very rewarding.
After taking a dozen
orders for the kit, I realized that this vintage aircraft model left a little nostalgia with the spectators. My
time has been well spent.
The modeler wishing to purchase the fuselage may send an inquiry to Bob Palmer,
9161 Morehart Ave., Arleta, Calif. 91331.
Lockheed Sirius Plans
<click for larger version>
Lockheed Sirius 3-View
<click for larger version>
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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