visitor Wells S. just wrote asking for another article to be posted
- this time it is a very nice scale radio controlled Spitfire IX.
As was common in the era (1962), construction is very robust and
therefore heavy (10 pounds with a 64" wingspan). A Super Tigre .56
powered the model in the article, and an Orbit radio with Bonner
servos were used. My favorite line in the article is, "In flight
the Spitfire is very stable but snaps through maneuvers and will
tie knots in itself if you can operate transmitter switches fast
enough." We've come a long way, baby.
How to Build George Harris'
Magnificent Radio Controlled Spitfire
of the most beautiful aircraft ever built, with all-elliptical surfaces,
was the Supermarine Spitfire. Designer was R. J. Mitchell who was
also responsible for a series of racing seaplanes which included
every British winner of the Schneider Trophy races from 1918 to
the end of the contests - which resulted in the outright winning
of the trophy for Britain.
The prototype Spitfire which
first flew on March 5, 1936 was an outstanding success, but Mitchell
died in 1937 before his creation began the job for which it was
designed. During the Battle of Britain, the Spitfire - together
with the Hurricane and greatly outnumbered - smashed the Luftwaffe
and ruined Hitler's invasion plans. While various modifications
greatly improved the Spitfire, the Focke Wulf 190 appearing in late
1941 was a serious threat. In answer to this menace a much improved
Rolls-Royce Merlin engine was fitted to a strengthened airframe
to give the Spitfire IX. The most obvious changes in the Mark 9
were the lengthened nose, large "flattop" cowling and equal size
radiators under each wing.
This aircraft had a top speed
of 408 mph at 25,000 feet and a rate of climb that was most upsetting
to the enemy. The Spitfire was the only Allied aircraft to remain
in production throughout the war. The last one built was an F.24
delivered in February 1948. Final operational flights by Spitfires
were in mid-1957.
Since scale modelers are a demanding bunch,
the markings have been kept authentic and several different aircraft
squadron designations have been given as alternatives. The camouflage
scheme and R.A.F. markings are as applied during the appropriate
Originally a 70 inch span Spit built as a test bed
for this type of model flew with a Fox .59, followed by a McCoy
60. This model has made almost 100 flights and, despite its heavy
weight of 10-lbs, is very aerobatic, even in a glide. A second,
smaller model to accurate scale with full war paint proved to be
even more aerobatic. So far the second, shown in the photographs,
has made 113 flights. It is momentarily retired after the right
landing gear leg snapped off at the bend while landing across a
Real Spit Mark 9 flies with beer barrel under each wing
to landing strip on Normandy beachhead soon after D-Day.
Full size plans for radio controlled Spitfire are available
from Hobby Helpers as part of group #262 (see ad for data).
Spitfires in flight.
Test pilot for the project was Ed Fitzgibbon of the San Diego Drones
R/C club, who went through all the usual tricks plus a few unusual
ones. Most of the flying was with a Super Tigre .56 - but a .45
will be plenty when the structure. is lightened as shown in the
plans. When modified Hassad .65 was installed the Spit just spiraled
itself up into the clouds.
STRUCTURE. The model is not intended
for beginners, so details like control systems and equipment installations
have been skipped. Most experienced modelers have their own ideas
about such things anyhow and their equipment varies considerably.
The fuselage is built upside-down on the crutch directly
on the bottom view, the basic structure completed to a considerable
degree before removal. This ensures a true alignment which is essential
in a large, fast model. The ply sides key into the formers and the
separate side pieces lock the whole assembly together, The rear
formers are held erect by the bottom longeron, the main part of
the planking being easily applied in this position.
structure is now removed from the board and the upper section added.
Note that the fin fairs smoothly into the rear fuselage with no
definite break. The tailplane installed at this point rests atop
Tail construction is simple, the tailplane being
covered with 1/16" sheet and the elevators silked. On the original
model the tail assembly, separate and held by rubber bands, has
never been removed since the first flight, so the drawings show
it all in one lump with the fuselage. This arrangement is lighter
and if a crash is hard enough to knock the tail loose, your repairs
are going to be extensive anyway. The tailwheel hook-up should be
made before completing planking; don't use anything less than 3/32"
wire for the tail wheel strut. Keep the tail light and beef up the
nose to eliminate later ballast. The 1/8" planking on the fuselage
may seem a little heavy, but there is not too much inner structure
and sanding will reduce it some.
A covering of fiberglass
on the nose back to the wing will help a lot in rough landings.
Details such as the reflector gun sight and rear view mirror help
a lot toward realism and don't require much time to make. The instrument
panel layout is shown, but accurate dials are a bit impractical
in this size, except to the real fanatic who will probably have
access to photographs of the things anyway. Cockpit framing is cut
from green plastic or cloth tape and seems to stay on very well
in use. The large wing root fillets are no problem if made from
narrow strips; the thin ply platform provides a very firm support
for the wing. If 1/32" ply is not available in the required size,
hard 1/16" balsa can be used with the grain across the fuselage.
Up at the front end the ply motor plate allows installation
of different motors without carving on the motor mounts. Cut the
removable top cowl to fit around your particular motor, have an
ample cutout for exhaust. A large spinner as shown may be a slight
problem but it can be made from fiberglass or compounded from a
small spinner with a built-up back section. The one in the photos
is custom made hand-spun aluminum.
Wings are best
built with the bottom main spars flat on the plans, the other members
packed up with scrap to proper height. Laminated leading edges simplify
curvature and are very strong. Covering the wings completely with
sheet balsa adds very little to the weight and increases strength
tremendously, in addition to giving an appearance of metal covering.
The only fabric covered surfaces on the Spit are the rudder and
elevators, so that's the way our model is built. Both wings are
joined and the landing gear and aileron controls installed before
sheeting. Ailerons and associated shroud inner surfaces are best
painted before assembly for neat appearance. Aileron hinges in scale
position are very strong and smooth in operation. Use good strong
brackets or many J-bolts to hold the landing gear on the 1/4" ply
Wing radiators are realistic with insect
screen inserts to simulate cores, the insides between the screen
pieces being painted black. The screen material offers little drag
and, for a gimmick, a toy whistle can be concealed in one to give
a Merlin whine in flight. The tubes through the wing fillets provide
a neat solution for the rubber retaining bands without any strain
on the fillets.
Cannons built around aluminum tubes
are held on by short dowel plugs which are easily replaced if knocked
off in a crash. The Spitfire IX had a "universal" wing which could
carry four 20mm cannons or two cannons and four .303 machine guns
- most had the latter with two cannon ports blanked off.
FINISHING. Considering the stresses involved in violent aerobatics
it is advisable to hold everything together with silk covering all
over, filled and doped to a smooth consistency. The basic color
of the Spitfire is gray and the true color is closely matched by
Fuller's Butyrate Dope, Aircraft Gray for the under surfaces. Dark
gray for the top surface is obtained by mixing about one part black
to five parts of the gray. Incidentally, AeroGloss mixes very well
with Fuller's dope which comes in quart cans, one being ample for
the Spit. AeroGloss Stinson Green is the camouflage green, the red,
white, blue and yellow being standard insignia colors. The light
gray letters on the fuselage are of the basic gray with a little
white added and the spinner and rear fuselage band are a very light
blue made by adding just a touch of blue to white dope.
CONTROLS AND FLYING. My original model used Bonner servos and Orbit
radio, but the space available is ample for all the popular equipment.
If you use Space Control an opening should be cut in F3 and the
servo rails extended from F2 to F5 to carry the mounting platform.
The receiver can then be adjusted fore and aft for balance. Control
movements need not be excessive - the surface areas are large and
the plane is very responsive.
In flight the Spitfire
is very stable but snaps through maneuvers and will tie knots in
itself if you can operate transmitter switches fast enough. There
is no tendency to fall off in tight banks; inverted flight is a
cinch. Glide characteristics are good and stalling speed low, although
the Spit should be flown into a landing rather than just dropped
and flopped. Even with that narrow track landing gear ground looping
is not a problem.
Watching the Spitfire in the air
brings back nostalgic memories to those of us who saw the real thing
in action... the war paint and little details being very convincing.
About the only requirement for complete realism would be a retracting
landing gear - this is planned for a near future project.
Spitfire IX Fuselage & Empennage
Spitfire IX Wing Plans Sheet
Spitfire IX List of Materials
SHEET BALSA: 4 sheets, 3/32 x 4 x 36 for Wing & tail ribs,
trailing edges; (14) 1/16 x 4 x 36 for Wing & tail sheeting;
(6) 1/8 x 4 x 36 for Fuselage formers & planking, wing L.E.;
3/16 x 3 x 36 for Elevator T.E., wing ribs; 1/4 x 4 x 36 for Wing
rear spars, fin spars, rudder outline; 3/8 x 3 x 36 for Wing radiators,
cannon blisters; 1/2 x 3 x 36 for Wing radiators; 3/4 x 4 x 24 for
Top cowl sides, nose sides, wing tips, rudder base block.
STRIP BALSA: 2 pieces 1/2 sq. for Tailplane spars; (7) 1/2 x
1/4 for Crutch, wing spars; (4) 1/4 sq. for Wing rear spars, fuselage
BLOCK BALSA: 1 piece, 2 x 5 x 9 for Lower nose
block; 1·1-3/4 x 1 x 5 for Carb. air intake.
piece, 10 x 15 x 1/32 ply for Wing platform; 4 x 12 x 1/16 ply for
T.E. fairing, canopy arch; 12 x 30 x 3/32 ply for Fuselage box frames,
windshield frame; 12 x 16 x 1/8 ply for Formers, rear spar joiners;
4 x 16 x 1/4 ply for Main spar joiners, motor plate; 3/4 x 3/8 x
24 maple for Motor mounts; 3/8 x 1/4 x 12 spruce for Servo rails;
1/4 dowel x 15 for Wing & top cowl retaining dowels.
PIANO WIRE: 2 pieces, 1/16 dia. x 36 for Aileron & rudder
linkage; 3/32 dia. x 18 for Aileron hinges, tail wheel strut; 5/32
dia. x 36 for Landing gear.
MISC.: 1 pair 3-1/2 dia. wheels;
1-1/4 dia. wheel; 3/32 I.D. x 12 brass tube for aileron & tail
wheel hinges; 3/16 I.D. x 20 alum. tube for cannons. Elevator horn,
hinges, push rods, pilot head, canopy, plastic for windows, green
plastic tape, spruce for antenna & pitot head, landing gear
brackets, nuts & bolts.
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.
Try my Scale Calculator for Model Airplane Plans.
Posted on May 29, 2013