visitor Garry O. wrote to request that I post this article featuring
the Vickers-Supermarine Spitfire Mk IIA. With its elliptical wing
planform and outward-retracting landing gear, is considered one
of the most attractive airplanes ever to come out of England. It,
along with the North American Mustang, are probably the two most
modeled fighters from World War II. This .61-powered control-line
model by Malvin Meador won the 1971 Nationals for control-line scale.
It has operating retractable gear, flaps, sliding canopy, navigation
lights, and drop tanks.
Plane on the Cover
Spitfire Mk IIA
Model that won the '71 CL Nats and was
6th at the '72 CL Scale World Champs is patient project of a great
plane. Has many operating features and flies quite well.
By Malvin Meador
Photos by Bill Boss and the Author
Scale builder has a favorite airplane or type of airplane; I've
always been inclined toward World War II military aircraft. After
moderate success in local scale contests, I decided to build a ship
for entry in the 1971 Nationals. To do this, I needed a subject
which inspired me to invest the amount of time required to complete
a competitive scale model. Retractable landing gear - an operating
feature having good spectator appeal and a high scoring flight demonstration
option - was a must. Another point relevant to selecting a subject
was additional operating features such as flaps, sliding canopy,
navigation lights, drop tanks, etc., which could be incorporated.
Also, I wanted to stay away from subjects which had been overdone.
One aircraft kept coming to mind, the Supermarine Spitfire.
It was one of the most famous World War II fighters, plenty of reference
material was available and, despite its fame, it didn't enjoy much
popularity with modelers. The Spitfire had enough operating features
to insure a respectable scale flight score, and it featured very
simple retractable landing gear which could be easily adapted to
Bill Johnson's efficient, lightweight Centrak gear retraction unit.
Using this system would eliminate the mess of batteries, extra control
lines, electrical wiring, and other assorted headaches which go
with retractable gear in control line models. Also, the simplicity
of the landing gear would make it fairly easy to machine scale shock
absorbing gear struts for added realism.
While considering the positive and negative aspects of the Spitfire
as a flying scale project, one nagging thought kept coming to mind:
The extremely short nose moment, small empennage areas, and fore
and aft placement of the landing gear on the prototype could make
the model's flying characteristics less than satisfactory. However,
after reading a very scientific conclusion that "anything will fly
on control lines," I decided to proceed with construction. The resulting
model did fly satisfactorily, but it is definitely not a beginner's
ship-the Spitfire demands the flier's undivided attention from takeoff
to the end of the last taxi lap.
Nice facet of real plane was its plywood covered wings. Detailing
is complete without yards of rivet lines.
A Bill Johnson Centrak gear is used. At speed in flight, centrifugal
force working against a spring raises the gear. Very reliable.
With flaps down one sees even more detail, including flap position
indicator finger which lifts through a coyer on wing top surface.
Oil cooler door also operates.
All smooth areas of the model are fiberglassed, including some
detail items such as simulated exhaust stacks.
Before surface finishing, cockpit interior is completed. Door
hinges open to reveal many more details, note canopy slides
All control surfaces have simulated fabric covering. Note full
Which variant of the Spitfire
to build was the final problem. The solution was dictated by the
availability of reference material, and I settled on the Mark IIA
depicted in Profile Publication, No. 41. Several variants
of the Spitfire shared a basic airframe; it is simple to convert
the Mark IIA to a Mark I, III, or V, and substitution of four 20mm
cannons for the inboard .303 caliber machine guns converts the model
to a Mark IIB.
Before beginning construction, study
every available publication on the Spitfire to become familiar with
details of the prototype. I found the following references to be
particularly helpful: Bruce Robertson's Spitfire: The Story
of a Famous Fighter, and Aircraft Camouflage and Markings,
1907-1954 both available from Harleyford Publications; Profile
Publications, Nos. 41 and 166; Aero Publisher's Supermarine
Spitfire; and Willis Nye's excellent drawings of the Spitfire. These
publications contain many drawings and photos invaluable for detailing
the model and preparing the proof of scale presentation which must
accompany it in competition.
Construction may be greatly
simplified with installation of conventional non-retractable gear.
However, the satisfaction of seeing the wheels disappear into the
wings shortly after takeoff makes the extra effort worthwhile. If
you use the Centrak installation, contact Bill Johnson, 2504 Charwood
St., Charles, Mo. 63301. Bill is familiar with the model and can
supply the retract unit and complete instructions for installation
At Nats, Malvin won scoring 517 points. He
also won Sterling Award for highest static points.
The landing gear is the
most complicated component and is a good place to begin. The gear
struts are turned from aluminum stock and a 7/32" diameter bore
drilled and reamed for the oleos. Drill holes for the oleo retaining
pin and the gear support rod, making sure the centerline of each
hole is at the proper angle (see plans). This is necessary for correct
tracking of the wheels and for maintaining correct gear geometry
The oleos are machined from mild steel
(I used 5/16" steel bolts). and the axles are 1/8" music wire threaded
on both ends and silver soldered into tapped holes in the oleos.
Exercise caution when drilling the holes in the oleos to insure
correct alignment of each component. File the top of each strut
to the shape shown, and assemble the struts and gear support rods,
keying in place as illustrated in the plans. Fabricate the spacers,
bushings, and mounts from brass tubing and sheet and the gear actuating
arms from mild steel; assemble, making certain that the gear mounts
rotate freely on the support rods and that the actuating arms are
silver soldered in place at the correct angle. Selection of springs
for the oleos depends on the final weight of the model and the amount
of shock absorbing action desired. The oleos can be removed easily,
so experimentation with various springs presents no problem.
One further note on the landing gear: If the Banner wheels shown
on the plans are used, the aluminum hubs must be faced off on each
side to give a thinner contour and allow the gear to retract fully
into the wheel wells.
The wing contains almost all the gear,
flap, and other control operating mechanisms and is the next component
to build. Cut ribs R-2, R-10, and R-15 to shape and drill 1/8" holes
in each one at the location shown on the plans. Stack the correct
number of 1/8" balsa rib blanks in sequence with the pattern ribs,
using 1/8" dowels to maintain alignment. Shape the stack of ribs
in the usual manner, with one exception: The stack should show a
curve, top and bottom, from the root to the tip rib. This is because
the upper and lower wing surfaces are curved as viewed from the
Join the balsa wing spars and plywood doubler, and
glue the ribs in place on the spar. Use two 20" lengths of 1/8"
doweling in the holes previously drilled in each rib to maintain
rib alignment until the glue dries. When dry, notch the ribs and
install stringers for the flap wells and aileron cutouts.
The bottom surface of the outer wing panels should be sheeted
next. Leave the bottom center section open until the wing is in
place on the fuselage and all control linkages are hooked up and
operating properly. The flap and aileron wells should not be cut
out until the tops of the outer wing panels have been covered and
the wing sanded to shape.
Cut the openings for the landing gear wells in the bottom of each
wing and remove sections of ribs as required. Then line the wells
with 1/16" balsa. To install the landing gear, it is necessary to
cut a small hole in the wing bottom sheeting between the leading
edge and front spar. Before final gluing of the plywood landing
gear mounts, check gear alignment carefully both in the extended
and retracted position.
the Centrak unit with the Roberts Flight Control, control line leadouts,
and control linkages attached. Bend and install the 3/32" music
wire gear actuating arms. Be certain that e rods are the correct
length to actuate both gear simultaneously-they m s: both be full
up and full down at same time. Install the Centrak spri leaving
the end which attaches to control unit free. This will allow ' r
movement of the landing gear to check for proper fit in the wheel
wells as construction progresses.
Now is the time to install
linkage for moveable ailerons, navigation lights and wiring, flaps,
etc., if you wish. The wing tip lights on the original were left
hanging from the end of the wing until the tips and top covering
were in place and the wing shaped. They were then epoxied in place,
covering the bulb completely with epoxy. When dry, the epoxy was
filed and sanded to form the lens and housing, and the entire area
was painted the color of the lens. (Red on the left wing and green
on the right wing. Mask the lens area, and paint the surrounding
area silver. The silver dope is covered by the finish coat later
and allows light to shine through the lens but not the surrounding
The fuselage is constructed of balsa blocks glued
to a built up crutch. The various blocks are tack glued in
place and the entire fuselage is carved a sanded to shape, using
cross section templates. After shaping the fuselage, remove the
blocks and hollow as much as possible without sacrificing strength,
particularly in the aft sections of the fuselage. Shape and glue
1/16" formers inside the blocks in the positions shown on the plans.
This provides stiffness without adding excessive weight.
Epoxy the fuselage crutch to the wing, lining the wing up carefully
to insure correct incidence and planform alignment.
horizontal and vertical stabilizers can be built up, or made by
laminating two 1/8" balsa sheets with a hollow 1/4" balsa core.
I tried both methods, and the weight difference using the latter
method is negligible if you choose your wood carefully (Sig contest
balsa was used on the original). The elevators and rudder are solid
contest balsa, hinged as shown on the plans. This type of hinge
is slightly difficult to construct, but it closely approximates
the hinges used on full scale aircraft.
Glue the empennage
in place, complete all linkage hookups, and install all lower fuselage
blocks and wing center section sheeting. Note that the bottom center
wing covering is flat at the front and blends to an inverted gull
section at the flaps.
Most of the cockpit details
on the original were finished prior to installation of the upper
fuselage blocks. When the cockpit area is finished to your satisfaction,
glue these blocks in place, add the wing fillets, and the model
is ready for finishing. I used Sig polyester resin and fiberglass
cloth on the original. I have tried many finishing methods, and
found that the use. of fiberglass results in an extremely tough
model, requires less time than dope and silk, and makes detailing
(such as scribing panel outlines) much easier. The finished model,
ready to fly, weighed in at six lb. 12 oz. which compares favorably
with other models of this type. The use of fiberglass doesn't present
a weight problem if it is applied sensibly.
To finish the
model using fiberglass, give the airplane a final sanding, making
certain that all contours and shapes are correct. Cut a piece of
glass cloth slightly larger than the area to be covered, lay it
in place, and coat liberally with polyester resin. The cloth to
cover the adjoining section should overlap with that already applied.
Sand the resin in the overlap area to insure good adhesion.
After completing the first coat, sand the entire coating with
coarse paper (80 grit aluminum oxide paper works well) to remove
gloss and rough edges. Use a sanding block where possible to maintain
the basic contours of the model. Apply a coat of resin only, and
wet sand with 220 and then 320 wet or dry paper. The model is now
ready for a coat or two of clear dope followed by color. I used
Pactra military flats with excellent result.
One final note
on finishing. Component parts such as ailerons, flaps, elevators,
rudder, etc., should be as nearly finished as possible before installation.
I try to have them ready for the final color coat before attaching
them to the model. This requires the builder to apply the finishing
steps outlined above to certain parts of the model such as aileron
wells, flap wells, and horizontal and vertical stabilizer trailing
edges before finishing the adjacent area. Care must be exercised
when fiberglassing and painting to prevent spoiling an already finished
<click for larger version>
<click for larger version>
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 January 21, 2012