Grumman F-4F Wildcat - 2004/04

by Jim Ryan
Grumman F-4F
Jim’s little Wildcat performs exactly as all of his other electricpowered
warbirds do—outstandingly!
April 2004 63
IN THE DARK early days of World War II, before world-class
carrier fighters such as the Grumman Hellcat and Chance Vought
Corsair entered service, hard-pressed US naval aviators depended on
the obsolescent Grumman F-4F Wildcat to parry the Imperial
Japanese Navy’s attacks. Although their mounts were inferior to the
renowned Mitsubishi A6M2 “Zero” in most respects, the Navy pilots
used superior tactics and gunnery training to take the measure of
their combat-hardened Japanese opponents.
In the first year of the war, Navy and Marine F-4F squadrons
confronted the Japanese Navy’s best air crews in four major carrier
battles and the grinding battle of attrition on and around
Guadalcanal. These battles cost the Japanese many of their most
experienced aviators; the result was that by the time Corsairs and
Hellcats entered service in 1943, the tide of war had already turned.
US Navy fighters are among my favorites, and having built
models of the Hellcat, the Grumman Bearcat, and the Corsair, the
time seemed ripe to round out my collection of classic WW II carrier
fighters.
For the Wildcat I stuck with my tried-and-true formula, scaling
Electrified RC Scale
version of Grumman’s
feisty fighter
64 MODEL AVIATION
Anyone for a dogfight? The Wildcat looks ready for action sitting in its custom cradle. This airplane has character!
You can see the paint detail, including simulated retracted landing
gear. You can use several paint schemes on this model.
This design has many focal points, such as the ring cowl
and the canopy framing. Notice the simulated radial engine!
There is a great deal of room in the model’s wide fuselage
for the radio gear and batteries. Keep it neat!
Flight shots courtesy of John Vago Static shots courtesy of the author
April 2004 65
Begin construction by making a “kit” of the precut parts. This
speeds assembly considerably.
Assemble fuselage formers and stringers over the disposable
internal crutch. This assembly is light and strong.
After you have completed the Wildcat’s fuselage, remove the
“crutch grips” of formers F-4 and F-5.
Join two wing panels with an inch dihedral per panel. Reinforce
center joint with fiberglass tape, then cut ailerons free.
Glue 1⁄64 plywood F-1 former to front of balsa cowl block. Glue
block to front of fuselage and carve to shape.
Install aileron torque rods in a slot cut in the bottom of the wing,
and then fill the slot with scrap balsa.
66 MODEL AVIATION
Once wing is mounted, glue tail assembly in place. With wing
resting on blocks, square vertical fin to building board and set
stabilizer incidence with small spirit level.
Once vertical fin is glued in place, apply filler to make smooth
radius from fuselage to raised headliner fairing.
Assemble formers,
stringers for belly
pan with wing
fitted to fuselage;
be careful not to
glue them to
fuselage. Note
“keeper box” for
wing mounting
screw.
the airframe to 170 square inches of wing area and aiming for an all-up
weight of 18 ounces. At this size the F-4F has a proportionally fatter
fuselage than any of my efforts to date, so weight control is crucial.
With the F-4F’s midwing configuration, I also had to pay special
attention to the structure around the wing saddle. Given the fuselage’s
shape, my favored practice of crutch-built construction worked
especially well. The Wildcat has lived up to all my expectations and is
one of my favorite models, so let’s get started!
CONSTRUCTION
The airframe was designed with AutoCAD. The fuselage is a
conventional structure using former, stringer, and balsa-sheet
construction, and the wing is foam sheeted with balsa. The weight goal
for the finished empty airframe is 7 ounces. I use regular thin
cyanoacrylate glue for nearly all construction and odorless
cyanoacrylate for the foam wing.
I suggest that you start with a “kit,” by precutting all major parts to
shape. You can accomplish this in one or two evenings, and
construction will go much more quickly. I transfer the part templates to
the sheet wood with the acetone transfer method, which is quick and
easy to do. (I’m offering a parts pack including the foam wing cores
and a vacuum-formed canopy. Send $24 [including shipping] to me at
the address at the end of this article.)
Wing: Lightly sand the foam cores, and clean them off with a Shop-
Vac or tack rag. Install the 1⁄16-inch sub-leading edges (LEs) with thick,
odorless cyanoacrylate and trim them flush. Glue the wing skins up
from 1⁄32 balsa and block-sand them smooth. After you have sanded
and dusted the skins, attach them with your favorite epoxy or contact
adhesive. Now 3M Super 77 contact adhesive contains acetone and is
unsuitable for use on foam wing cores.
Trim the wing skins flush with the sub-LEs, and then install the 1⁄8-
inch LE caps. Trim the roots and tips flush with the cores, and then
trim the trailing edges (TEs) as shown on the plans. Install the 1⁄2-inch
balsa wingtips and carve them to shape.
Cut the ailerons from the wing panels as shown on the plan view
and apply 1⁄8 balsa strips to the exposed TE. Trim 1⁄4 inch from the LEs
of the ailerons and install their 1⁄8-inch balsa LEs. You can trim the
ailerons shorter and face their ends with 1⁄32 balsa.
Before joining the wing panels, you need to bevel the roots to the
proper angle. Align the root of the wing panel with the edge of your
workbench, and block up the wingtip an inch. Use a sanding block to
bevel the root. Repeat with the other panel. Then, again blocking each
wingtip up an inch, join the wing panels with thick, odorless
cyanoacrylate or epoxy. Apply 1.5-ounce fiberglass reinforcement tape
April 2004 67
Grumman Finished airframe is
ready for covering.
Prototypes were
covered with ultralight
fiberglass
cloth and then
painted. Film
covering or tissue
and dope will also
work well.
to the joint with thin, odorless cyanoacrylate.
Install the aileron torque rods. They are fabricated from 1⁄16-inch
music wire and 3⁄32-inch brass tubing. The torque rods mate with the
ailerons at the very end, forming the inboard hinge for the surface. The
easiest way to install the torque rods is to cut through the bottom
sheeting, remove the underlying foam, and then mount them with
thick, odorless cyanoacrylate, being careful not to get any glue inside
the brass tubes.
Fill in the slot with 1⁄8 balsa and block-sand it flush. Cut the hinge
slots and dry-mount the ailerons. Install the 1⁄16-inch plywood aileron
servo mount after you finish the wing.
Fuselage: The fuselage is built over a crutch, which is indexed for
each former location. Before beginning fuselage construction, glue the
3⁄16 square hard-balsa spine down the center of the crutch to make it
more rigid. Make sure that the crutch is flat and straight. It is to be
removed when the fuselage is complete. Do not glue any of the
formers to the crutch!
Before you begin assembling the fuselage framework, assemble F-
6, F6-A, and F-6B. You must bevel and join them at the proper 30°
angle to allow removal of the wing. Glue the reinforcement strips and
extension stringers onto the wing-saddle doublers. Notice the partial
cutouts in the “crutch grips” of F-4 and F-5; you will remove these
sections after you have completed the fuselage.
Slide each former over the crutch, into its indexed position. Be
especially careful to keep F-2 square to the crutch and not induce
warpage while adding the stringers; this former determines the
motor’s thrustline.
Dry-fit the 3⁄32 x 3⁄16 stringers and wing-saddle doubler assemblies
into place. After making absolutely sure that each former is
perpendicular to the crutch, glue the stringers to the formers with thin
cyanoacrylate. The stringers that are part of the wing-saddle assembly
extend past F-9 by approximately two inches.
Assemble the F-10, F-11, and F-12 cockpit formers, and glue them
in place on formers F-4, F-5, and F-6. Glue the F-13 subturtledeck in
place atop formers F-12, F-6, F-7, and F-8. The pointed rear tip of the
turtledeck seats between the top two stringers just ahead of F-9. You
should now have a light and straight framework.
Glue the lower edge of the fuselage side panels to the side
stringers with thin cyanoacrylate. It’s best to install each pair of
panels simultaneously so that stresses aren’t induced in the
assembly. Make sure that the side panels overlap exactly half of
the side stringers; it helps to make a light pencil mark at the
center of the side stringers at each former.
If necessary, dampen the fuselage panels so that they’ll bend
readily, and then carefully push them into place and glue them with
thin cyanoacrylate. Glue the upper fuselage panels in place edge to
edge with the fuselage sides. It’s best to start at the middle of the panels
and work toward the ends. Add the rest of the fuselage panels.
Type: Electric RC Sport Scale
Wingspan: 30.6 inches
Power: Speed 400 motor with eight HE1000 NiMH cells
Flying weight: 18 ounces
Construction: Balsa, plywood, foam
Covering/finish: Fiberglass cloth, modeling paint
Grumman F-4F
68 MODEL AVIATION
Once all fuselage panels are in place, glue
the bottom tail block in place and carve it to
shape. Plane or block-sand the turtledeck
panels flush with the subturtledeck and add the
turtledeck cap, which is laminated from two
layers of 1⁄8 balsa.
Now you can remove the construction
crutch. By this point the assembly should be
stiff. Remove the crutch grips from F-4 and F-
5 by cutting through the remaining tabs. The
main fuselage structure is now complete.
Wing Installation: Block-sand the wing’s LE
at the root so that it will have a flat face
against F-3, and then trim the TE at the root so
that it will fit into the wing saddle. Tap the 1⁄16
plywood wing mount for a 6-32 nylon screw,
glue the mount in place in the fuselage, and
reinforce the joint with 1⁄4 balsa triangle stock.
Drill the screw hole through the wing and
install the 6-32 nylon wing screw. Square the
wing with the tail of the fuselage, pinning it in
place in the proper position. Drill the wing’s
LE to accept the 1⁄8-inch locator dowel.
Cowl Block: The cowl is a block of end-grain
balsa that is carved to shape. Notice that the
block is bored for the motor opening. Draw
datum lines on the front of the block and use
them as a guide for installing F-1, which is
really just a sanding guide. Glue the block in
place onto F-2 and carve and sand it to final
shape. I recommend waiting until the model is
covered to install the 1⁄16 plywood motor
mount.
Empennage: To have the necessary strength
at the stabilizer mounting, make the vertical
fin from 3⁄16 balsa. To reduce weight and
improve the appearance, block-sand the fin to
taper from 3⁄16 inch at the stabilizer slot to 1⁄8
inch or less at the tip. You should also sand it
to a symmetrical airfoil section. Cut the
stabilizer and elevator halves from 1⁄8 sheet
stock. With the pieces trial-fit together, fit the
empennage assembly to the fuselage.
Assemble the wing to the fuselage. Pin the
vertical fin in place so that it’s 90° to the wing
and aligned with the axis of the fuselage. Glue
the tail fillet blocks (made from 1⁄2 balsa stock)
in place on either side of the vertical fin, but be
careful not to glue them to the vertical fin at
this time. Remove the vertical fin and replace
it with a spacer made from scrap 3⁄16 balsa.
Carve and sand the turtledeck cap and tail
fillets to shape. Remove the spacers and slip
the vertical fin back into place, again making
sure that it’s 90° to the wing. Dry-fit the
stabilizer in place, and check to make sure that
it’s at 0° incidence relative to the bottom of the
wing. When you’re satisfied with the
alignment, glue the vertical fin in place with
thin cyanoacrylate, but leave the stabilizer
loose for the moment.
Cut the elevator hinge slots and test-fit
them. Install the music-wire elevator joiner (or
you can use a 1⁄8-inch-diameter dowel joiner if
you prefer). I found it easiest to wait and
permanently install the stabilizer after covering.
Belly Pan: With the wing mounted on the
fuselage, install the belly-pan formers on the
bottom of the wing, being careful not to glue
them to the fuselage. Dry-fit the three bellypan
stringers in place. The center stringer is
laminated from two layers of 3⁄32 x 3⁄16 balsa.
You may want to add a “keeper box” to hold
the wing screw in place in the wing.
Remove the wing from the fuselage,
leaving the screw in place in the wing, and
install the 1⁄16-inch belly-pan sheeting. Trim
and block-sand the front and rear edges flush
with the formers. Drill a 1⁄8-inch access hole
over the wing hold-down screw, and reinstall
the wing on the fuselage. Sand the joint
between the belly pan and fuselage sheeting
flush, being careful not to sand through the
sheeting.
Last Details: Install the servo mounts with
thin cyanoacrylate. Cut the battery mounting
plate from 1⁄16 balsa and install it on F-3 and F-
4, using 1⁄4 triangle stock to reinforce the
joints. Apply a strip of Velcro to the mounting
plate so that the battery pack can be secured.
I use .038 music wire for the pushrods to
keep weight to a minimum. On a model this
small, I prefer to make my control horns from
1⁄32 plywood, mortised into the surfaces for
added strength.
Finishing: The Wildcat is suitable for film
covering, but I like to finish my warbirds with
fiberglass and paint. Tissue and dope also
works well. I covered the prototype with .56-
ounce fiberglass cloth and painted it with
enamel paints. It’s a replica of the F-4F-3 that
Lieutenant “Butch” O’Hare flew when he
earned the Medal of Honor on February 20,
1942.
You can paint the canopy framing easily
using the frisket masks shown in the plans.
Make sure you protect the canopy’s inside
surface with masking tape; overspray gets
everywhere. After painting the framing,
remove the masks and glue the canopy in
place with Formula 560 or equivalent canopy
glue. Install the hardware, and you’re ready to
go fly.
Flight Testing: Be careful checking the center
of gravity (CG). I suggest that you start with
the CG two inches behind the LE of the wing
where it exits the fuselage, and adjust it to suit
your tastes. If you keep the weight near 18
ounces, the Wildcat should fly fine.
Get a capable assistant to hand-launch the
model on the first flights. It needs to be thrown
straight and level. If the launcher lobs it
upward, it’s likely to stall. Hold the wings
level and begin a shallow climb. Landings are
made with a straight-in approach, and the
model is held just off the ground until it settles
in. With the washout in the wing, the Wildcat
has forgiving stall characteristics.
I’ve been extremely pleased with this
model’s performance and handling. I use eight
cells to improve the vertical, but I spend most
of each flight at half to two-thirds throttle.
With the new HE1000 NiMH cells, endurance
is in the seven- to nine-minute range. The
Wildcat will do huge loops and Cuban 8s, and
the roll rate is surprisingly fast. Inverted flight
is solid. The Wildcat really is a joy to fly. MA
Jim Ryan
6941 Rob Vern Dr.
Cincinnati OH 45239
[email protected]
April 2004 69
Full-Size Plans Available—see page 207
Full-Size Plans Available—see page 207
70 MODEL AVIATION

by Jim Ryan
Grumman F-4F
Jim’s little Wildcat performs exactly as all of his other electricpowered
warbirds do—outstandingly!
April 2004 63
IN THE DARK early days of World War II, before world-class
carrier fighters such as the Grumman Hellcat and Chance Vought
Corsair entered service, hard-pressed US naval aviators depended on
the obsolescent Grumman F-4F Wildcat to parry the Imperial
Japanese Navy’s attacks. Although their mounts were inferior to the
renowned Mitsubishi A6M2 “Zero” in most respects, the Navy pilots
used superior tactics and gunnery training to take the measure of
their combat-hardened Japanese opponents.
In the first year of the war, Navy and Marine F-4F squadrons
confronted the Japanese Navy’s best air crews in four major carrier
battles and the grinding battle of attrition on and around
Guadalcanal. These battles cost the Japanese many of their most
experienced aviators; the result was that by the time Corsairs and
Hellcats entered service in 1943, the tide of war had already turned.
US Navy fighters are among my favorites, and having built
models of the Hellcat, the Grumman Bearcat, and the Corsair, the
time seemed ripe to round out my collection of classic WW II carrier
fighters.
For the Wildcat I stuck with my tried-and-true formula, scaling
Electrified RC Scale
version of Grumman’s
feisty fighter
64 MODEL AVIATION
Anyone for a dogfight? The Wildcat looks ready for action sitting in its custom cradle. This airplane has character!
You can see the paint detail, including simulated retracted landing
gear. You can use several paint schemes on this model.
This design has many focal points, such as the ring cowl
and the canopy framing. Notice the simulated radial engine!
There is a great deal of room in the model’s wide fuselage
for the radio gear and batteries. Keep it neat!
Flight shots courtesy of John Vago Static shots courtesy of the author
April 2004 65
Begin construction by making a “kit” of the precut parts. This
speeds assembly considerably.
Assemble fuselage formers and stringers over the disposable
internal crutch. This assembly is light and strong.
After you have completed the Wildcat’s fuselage, remove the
“crutch grips” of formers F-4 and F-5.
Join two wing panels with an inch dihedral per panel. Reinforce
center joint with fiberglass tape, then cut ailerons free.
Glue 1⁄64 plywood F-1 former to front of balsa cowl block. Glue
block to front of fuselage and carve to shape.
Install aileron torque rods in a slot cut in the bottom of the wing,
and then fill the slot with scrap balsa.
66 MODEL AVIATION
Once wing is mounted, glue tail assembly in place. With wing
resting on blocks, square vertical fin to building board and set
stabilizer incidence with small spirit level.
Once vertical fin is glued in place, apply filler to make smooth
radius from fuselage to raised headliner fairing.
Assemble formers,
stringers for belly
pan with wing
fitted to fuselage;
be careful not to
glue them to
fuselage. Note
“keeper box” for
wing mounting
screw.
the airframe to 170 square inches of wing area and aiming for an all-up
weight of 18 ounces. At this size the F-4F has a proportionally fatter
fuselage than any of my efforts to date, so weight control is crucial.
With the F-4F’s midwing configuration, I also had to pay special
attention to the structure around the wing saddle. Given the fuselage’s
shape, my favored practice of crutch-built construction worked
especially well. The Wildcat has lived up to all my expectations and is
one of my favorite models, so let’s get started!
CONSTRUCTION
The airframe was designed with AutoCAD. The fuselage is a
conventional structure using former, stringer, and balsa-sheet
construction, and the wing is foam sheeted with balsa. The weight goal
for the finished empty airframe is 7 ounces. I use regular thin
cyanoacrylate glue for nearly all construction and odorless
cyanoacrylate for the foam wing.
I suggest that you start with a “kit,” by precutting all major parts to
shape. You can accomplish this in one or two evenings, and
construction will go much more quickly. I transfer the part templates to
the sheet wood with the acetone transfer method, which is quick and
easy to do. (I’m offering a parts pack including the foam wing cores
and a vacuum-formed canopy. Send $24 [including shipping] to me at
the address at the end of this article.)
Wing: Lightly sand the foam cores, and clean them off with a Shop-
Vac or tack rag. Install the 1⁄16-inch sub-leading edges (LEs) with thick,
odorless cyanoacrylate and trim them flush. Glue the wing skins up
from 1⁄32 balsa and block-sand them smooth. After you have sanded
and dusted the skins, attach them with your favorite epoxy or contact
adhesive. Now 3M Super 77 contact adhesive contains acetone and is
unsuitable for use on foam wing cores.
Trim the wing skins flush with the sub-LEs, and then install the 1⁄8-
inch LE caps. Trim the roots and tips flush with the cores, and then
trim the trailing edges (TEs) as shown on the plans. Install the 1⁄2-inch
balsa wingtips and carve them to shape.
Cut the ailerons from the wing panels as shown on the plan view
and apply 1⁄8 balsa strips to the exposed TE. Trim 1⁄4 inch from the LEs
of the ailerons and install their 1⁄8-inch balsa LEs. You can trim the
ailerons shorter and face their ends with 1⁄32 balsa.
Before joining the wing panels, you need to bevel the roots to the
proper angle. Align the root of the wing panel with the edge of your
workbench, and block up the wingtip an inch. Use a sanding block to
bevel the root. Repeat with the other panel. Then, again blocking each
wingtip up an inch, join the wing panels with thick, odorless
cyanoacrylate or epoxy. Apply 1.5-ounce fiberglass reinforcement tape
April 2004 67
Grumman Finished airframe is
ready for covering.
Prototypes were
covered with ultralight
fiberglass
cloth and then
painted. Film
covering or tissue
and dope will also
work well.
to the joint with thin, odorless cyanoacrylate.
Install the aileron torque rods. They are fabricated from 1⁄16-inch
music wire and 3⁄32-inch brass tubing. The torque rods mate with the
ailerons at the very end, forming the inboard hinge for the surface. The
easiest way to install the torque rods is to cut through the bottom
sheeting, remove the underlying foam, and then mount them with
thick, odorless cyanoacrylate, being careful not to get any glue inside
the brass tubes.
Fill in the slot with 1⁄8 balsa and block-sand it flush. Cut the hinge
slots and dry-mount the ailerons. Install the 1⁄16-inch plywood aileron
servo mount after you finish the wing.
Fuselage: The fuselage is built over a crutch, which is indexed for
each former location. Before beginning fuselage construction, glue the
3⁄16 square hard-balsa spine down the center of the crutch to make it
more rigid. Make sure that the crutch is flat and straight. It is to be
removed when the fuselage is complete. Do not glue any of the
formers to the crutch!
Before you begin assembling the fuselage framework, assemble F-
6, F6-A, and F-6B. You must bevel and join them at the proper 30°
angle to allow removal of the wing. Glue the reinforcement strips and
extension stringers onto the wing-saddle doublers. Notice the partial
cutouts in the “crutch grips” of F-4 and F-5; you will remove these
sections after you have completed the fuselage.
Slide each former over the crutch, into its indexed position. Be
especially careful to keep F-2 square to the crutch and not induce
warpage while adding the stringers; this former determines the
motor’s thrustline.
Dry-fit the 3⁄32 x 3⁄16 stringers and wing-saddle doubler assemblies
into place. After making absolutely sure that each former is
perpendicular to the crutch, glue the stringers to the formers with thin
cyanoacrylate. The stringers that are part of the wing-saddle assembly
extend past F-9 by approximately two inches.
Assemble the F-10, F-11, and F-12 cockpit formers, and glue them
in place on formers F-4, F-5, and F-6. Glue the F-13 subturtledeck in
place atop formers F-12, F-6, F-7, and F-8. The pointed rear tip of the
turtledeck seats between the top two stringers just ahead of F-9. You
should now have a light and straight framework.
Glue the lower edge of the fuselage side panels to the side
stringers with thin cyanoacrylate. It’s best to install each pair of
panels simultaneously so that stresses aren’t induced in the
assembly. Make sure that the side panels overlap exactly half of
the side stringers; it helps to make a light pencil mark at the
center of the side stringers at each former.
If necessary, dampen the fuselage panels so that they’ll bend
readily, and then carefully push them into place and glue them with
thin cyanoacrylate. Glue the upper fuselage panels in place edge to
edge with the fuselage sides. It’s best to start at the middle of the panels
and work toward the ends. Add the rest of the fuselage panels.
Type: Electric RC Sport Scale
Wingspan: 30.6 inches
Power: Speed 400 motor with eight HE1000 NiMH cells
Flying weight: 18 ounces
Construction: Balsa, plywood, foam
Covering/finish: Fiberglass cloth, modeling paint
Grumman F-4F
68 MODEL AVIATION
Once all fuselage panels are in place, glue
the bottom tail block in place and carve it to
shape. Plane or block-sand the turtledeck
panels flush with the subturtledeck and add the
turtledeck cap, which is laminated from two
layers of 1⁄8 balsa.
Now you can remove the construction
crutch. By this point the assembly should be
stiff. Remove the crutch grips from F-4 and F-
5 by cutting through the remaining tabs. The
main fuselage structure is now complete.
Wing Installation: Block-sand the wing’s LE
at the root so that it will have a flat face
against F-3, and then trim the TE at the root so
that it will fit into the wing saddle. Tap the 1⁄16
plywood wing mount for a 6-32 nylon screw,
glue the mount in place in the fuselage, and
reinforce the joint with 1⁄4 balsa triangle stock.
Drill the screw hole through the wing and
install the 6-32 nylon wing screw. Square the
wing with the tail of the fuselage, pinning it in
place in the proper position. Drill the wing’s
LE to accept the 1⁄8-inch locator dowel.
Cowl Block: The cowl is a block of end-grain
balsa that is carved to shape. Notice that the
block is bored for the motor opening. Draw
datum lines on the front of the block and use
them as a guide for installing F-1, which is
really just a sanding guide. Glue the block in
place onto F-2 and carve and sand it to final
shape. I recommend waiting until the model is
covered to install the 1⁄16 plywood motor
mount.
Empennage: To have the necessary strength
at the stabilizer mounting, make the vertical
fin from 3⁄16 balsa. To reduce weight and
improve the appearance, block-sand the fin to
taper from 3⁄16 inch at the stabilizer slot to 1⁄8
inch or less at the tip. You should also sand it
to a symmetrical airfoil section. Cut the
stabilizer and elevator halves from 1⁄8 sheet
stock. With the pieces trial-fit together, fit the
empennage assembly to the fuselage.
Assemble the wing to the fuselage. Pin the
vertical fin in place so that it’s 90° to the wing
and aligned with the axis of the fuselage. Glue
the tail fillet blocks (made from 1⁄2 balsa stock)
in place on either side of the vertical fin, but be
careful not to glue them to the vertical fin at
this time. Remove the vertical fin and replace
it with a spacer made from scrap 3⁄16 balsa.
Carve and sand the turtledeck cap and tail
fillets to shape. Remove the spacers and slip
the vertical fin back into place, again making
sure that it’s 90° to the wing. Dry-fit the
stabilizer in place, and check to make sure that
it’s at 0° incidence relative to the bottom of the
wing. When you’re satisfied with the
alignment, glue the vertical fin in place with
thin cyanoacrylate, but leave the stabilizer
loose for the moment.
Cut the elevator hinge slots and test-fit
them. Install the music-wire elevator joiner (or
you can use a 1⁄8-inch-diameter dowel joiner if
you prefer). I found it easiest to wait and
permanently install the stabilizer after covering.
Belly Pan: With the wing mounted on the
fuselage, install the belly-pan formers on the
bottom of the wing, being careful not to glue
them to the fuselage. Dry-fit the three bellypan
stringers in place. The center stringer is
laminated from two layers of 3⁄32 x 3⁄16 balsa.
You may want to add a “keeper box” to hold
the wing screw in place in the wing.
Remove the wing from the fuselage,
leaving the screw in place in the wing, and
install the 1⁄16-inch belly-pan sheeting. Trim
and block-sand the front and rear edges flush
with the formers. Drill a 1⁄8-inch access hole
over the wing hold-down screw, and reinstall
the wing on the fuselage. Sand the joint
between the belly pan and fuselage sheeting
flush, being careful not to sand through the
sheeting.
Last Details: Install the servo mounts with
thin cyanoacrylate. Cut the battery mounting
plate from 1⁄16 balsa and install it on F-3 and F-
4, using 1⁄4 triangle stock to reinforce the
joints. Apply a strip of Velcro to the mounting
plate so that the battery pack can be secured.
I use .038 music wire for the pushrods to
keep weight to a minimum. On a model this
small, I prefer to make my control horns from
1⁄32 plywood, mortised into the surfaces for
added strength.
Finishing: The Wildcat is suitable for film
covering, but I like to finish my warbirds with
fiberglass and paint. Tissue and dope also
works well. I covered the prototype with .56-
ounce fiberglass cloth and painted it with
enamel paints. It’s a replica of the F-4F-3 that
Lieutenant “Butch” O’Hare flew when he
earned the Medal of Honor on February 20,
1942.
You can paint the canopy framing easily
using the frisket masks shown in the plans.
Make sure you protect the canopy’s inside
surface with masking tape; overspray gets
everywhere. After painting the framing,
remove the masks and glue the canopy in
place with Formula 560 or equivalent canopy
glue. Install the hardware, and you’re ready to
go fly.
Flight Testing: Be careful checking the center
of gravity (CG). I suggest that you start with
the CG two inches behind the LE of the wing
where it exits the fuselage, and adjust it to suit
your tastes. If you keep the weight near 18
ounces, the Wildcat should fly fine.
Get a capable assistant to hand-launch the
model on the first flights. It needs to be thrown
straight and level. If the launcher lobs it
upward, it’s likely to stall. Hold the wings
level and begin a shallow climb. Landings are
made with a straight-in approach, and the
model is held just off the ground until it settles
in. With the washout in the wing, the Wildcat
has forgiving stall characteristics.
I’ve been extremely pleased with this
model’s performance and handling. I use eight
cells to improve the vertical, but I spend most
of each flight at half to two-thirds throttle.
With the new HE1000 NiMH cells, endurance
is in the seven- to nine-minute range. The
Wildcat will do huge loops and Cuban 8s, and
the roll rate is surprisingly fast. Inverted flight
is solid. The Wildcat really is a joy to fly. MA
Jim Ryan
6941 Rob Vern Dr.
Cincinnati OH 45239
[email protected]
April 2004 69
Full-Size Plans Available—see page 207
Full-Size Plans Available—see page 207
70 MODEL AVIATION

by Jim Ryan
Grumman F-4F
Jim’s little Wildcat performs exactly as all of his other electricpowered
warbirds do—outstandingly!
April 2004 63
IN THE DARK early days of World War II, before world-class
carrier fighters such as the Grumman Hellcat and Chance Vought
Corsair entered service, hard-pressed US naval aviators depended on
the obsolescent Grumman F-4F Wildcat to parry the Imperial
Japanese Navy’s attacks. Although their mounts were inferior to the
renowned Mitsubishi A6M2 “Zero” in most respects, the Navy pilots
used superior tactics and gunnery training to take the measure of
their combat-hardened Japanese opponents.
In the first year of the war, Navy and Marine F-4F squadrons
confronted the Japanese Navy’s best air crews in four major carrier
battles and the grinding battle of attrition on and around
Guadalcanal. These battles cost the Japanese many of their most
experienced aviators; the result was that by the time Corsairs and
Hellcats entered service in 1943, the tide of war had already turned.
US Navy fighters are among my favorites, and having built
models of the Hellcat, the Grumman Bearcat, and the Corsair, the
time seemed ripe to round out my collection of classic WW II carrier
fighters.
For the Wildcat I stuck with my tried-and-true formula, scaling
Electrified RC Scale
version of Grumman’s
feisty fighter
64 MODEL AVIATION
Anyone for a dogfight? The Wildcat looks ready for action sitting in its custom cradle. This airplane has character!
You can see the paint detail, including simulated retracted landing
gear. You can use several paint schemes on this model.
This design has many focal points, such as the ring cowl
and the canopy framing. Notice the simulated radial engine!
There is a great deal of room in the model’s wide fuselage
for the radio gear and batteries. Keep it neat!
Flight shots courtesy of John Vago Static shots courtesy of the author
April 2004 65
Begin construction by making a “kit” of the precut parts. This
speeds assembly considerably.
Assemble fuselage formers and stringers over the disposable
internal crutch. This assembly is light and strong.
After you have completed the Wildcat’s fuselage, remove the
“crutch grips” of formers F-4 and F-5.
Join two wing panels with an inch dihedral per panel. Reinforce
center joint with fiberglass tape, then cut ailerons free.
Glue 1⁄64 plywood F-1 former to front of balsa cowl block. Glue
block to front of fuselage and carve to shape.
Install aileron torque rods in a slot cut in the bottom of the wing,
and then fill the slot with scrap balsa.
66 MODEL AVIATION
Once wing is mounted, glue tail assembly in place. With wing
resting on blocks, square vertical fin to building board and set
stabilizer incidence with small spirit level.
Once vertical fin is glued in place, apply filler to make smooth
radius from fuselage to raised headliner fairing.
Assemble formers,
stringers for belly
pan with wing
fitted to fuselage;
be careful not to
glue them to
fuselage. Note
“keeper box” for
wing mounting
screw.
the airframe to 170 square inches of wing area and aiming for an all-up
weight of 18 ounces. At this size the F-4F has a proportionally fatter
fuselage than any of my efforts to date, so weight control is crucial.
With the F-4F’s midwing configuration, I also had to pay special
attention to the structure around the wing saddle. Given the fuselage’s
shape, my favored practice of crutch-built construction worked
especially well. The Wildcat has lived up to all my expectations and is
one of my favorite models, so let’s get started!
CONSTRUCTION
The airframe was designed with AutoCAD. The fuselage is a
conventional structure using former, stringer, and balsa-sheet
construction, and the wing is foam sheeted with balsa. The weight goal
for the finished empty airframe is 7 ounces. I use regular thin
cyanoacrylate glue for nearly all construction and odorless
cyanoacrylate for the foam wing.
I suggest that you start with a “kit,” by precutting all major parts to
shape. You can accomplish this in one or two evenings, and
construction will go much more quickly. I transfer the part templates to
the sheet wood with the acetone transfer method, which is quick and
easy to do. (I’m offering a parts pack including the foam wing cores
and a vacuum-formed canopy. Send $24 [including shipping] to me at
the address at the end of this article.)
Wing: Lightly sand the foam cores, and clean them off with a Shop-
Vac or tack rag. Install the 1⁄16-inch sub-leading edges (LEs) with thick,
odorless cyanoacrylate and trim them flush. Glue the wing skins up
from 1⁄32 balsa and block-sand them smooth. After you have sanded
and dusted the skins, attach them with your favorite epoxy or contact
adhesive. Now 3M Super 77 contact adhesive contains acetone and is
unsuitable for use on foam wing cores.
Trim the wing skins flush with the sub-LEs, and then install the 1⁄8-
inch LE caps. Trim the roots and tips flush with the cores, and then
trim the trailing edges (TEs) as shown on the plans. Install the 1⁄2-inch
balsa wingtips and carve them to shape.
Cut the ailerons from the wing panels as shown on the plan view
and apply 1⁄8 balsa strips to the exposed TE. Trim 1⁄4 inch from the LEs
of the ailerons and install their 1⁄8-inch balsa LEs. You can trim the
ailerons shorter and face their ends with 1⁄32 balsa.
Before joining the wing panels, you need to bevel the roots to the
proper angle. Align the root of the wing panel with the edge of your
workbench, and block up the wingtip an inch. Use a sanding block to
bevel the root. Repeat with the other panel. Then, again blocking each
wingtip up an inch, join the wing panels with thick, odorless
cyanoacrylate or epoxy. Apply 1.5-ounce fiberglass reinforcement tape
April 2004 67
Grumman Finished airframe is
ready for covering.
Prototypes were
covered with ultralight
fiberglass
cloth and then
painted. Film
covering or tissue
and dope will also
work well.
to the joint with thin, odorless cyanoacrylate.
Install the aileron torque rods. They are fabricated from 1⁄16-inch
music wire and 3⁄32-inch brass tubing. The torque rods mate with the
ailerons at the very end, forming the inboard hinge for the surface. The
easiest way to install the torque rods is to cut through the bottom
sheeting, remove the underlying foam, and then mount them with
thick, odorless cyanoacrylate, being careful not to get any glue inside
the brass tubes.
Fill in the slot with 1⁄8 balsa and block-sand it flush. Cut the hinge
slots and dry-mount the ailerons. Install the 1⁄16-inch plywood aileron
servo mount after you finish the wing.
Fuselage: The fuselage is built over a crutch, which is indexed for
each former location. Before beginning fuselage construction, glue the
3⁄16 square hard-balsa spine down the center of the crutch to make it
more rigid. Make sure that the crutch is flat and straight. It is to be
removed when the fuselage is complete. Do not glue any of the
formers to the crutch!
Before you begin assembling the fuselage framework, assemble F-
6, F6-A, and F-6B. You must bevel and join them at the proper 30°
angle to allow removal of the wing. Glue the reinforcement strips and
extension stringers onto the wing-saddle doublers. Notice the partial
cutouts in the “crutch grips” of F-4 and F-5; you will remove these
sections after you have completed the fuselage.
Slide each former over the crutch, into its indexed position. Be
especially careful to keep F-2 square to the crutch and not induce
warpage while adding the stringers; this former determines the
motor’s thrustline.
Dry-fit the 3⁄32 x 3⁄16 stringers and wing-saddle doubler assemblies
into place. After making absolutely sure that each former is
perpendicular to the crutch, glue the stringers to the formers with thin
cyanoacrylate. The stringers that are part of the wing-saddle assembly
extend past F-9 by approximately two inches.
Assemble the F-10, F-11, and F-12 cockpit formers, and glue them
in place on formers F-4, F-5, and F-6. Glue the F-13 subturtledeck in
place atop formers F-12, F-6, F-7, and F-8. The pointed rear tip of the
turtledeck seats between the top two stringers just ahead of F-9. You
should now have a light and straight framework.
Glue the lower edge of the fuselage side panels to the side
stringers with thin cyanoacrylate. It’s best to install each pair of
panels simultaneously so that stresses aren’t induced in the
assembly. Make sure that the side panels overlap exactly half of
the side stringers; it helps to make a light pencil mark at the
center of the side stringers at each former.
If necessary, dampen the fuselage panels so that they’ll bend
readily, and then carefully push them into place and glue them with
thin cyanoacrylate. Glue the upper fuselage panels in place edge to
edge with the fuselage sides. It’s best to start at the middle of the panels
and work toward the ends. Add the rest of the fuselage panels.
Type: Electric RC Sport Scale
Wingspan: 30.6 inches
Power: Speed 400 motor with eight HE1000 NiMH cells
Flying weight: 18 ounces
Construction: Balsa, plywood, foam
Covering/finish: Fiberglass cloth, modeling paint
Grumman F-4F
68 MODEL AVIATION
Once all fuselage panels are in place, glue
the bottom tail block in place and carve it to
shape. Plane or block-sand the turtledeck
panels flush with the subturtledeck and add the
turtledeck cap, which is laminated from two
layers of 1⁄8 balsa.
Now you can remove the construction
crutch. By this point the assembly should be
stiff. Remove the crutch grips from F-4 and F-
5 by cutting through the remaining tabs. The
main fuselage structure is now complete.
Wing Installation: Block-sand the wing’s LE
at the root so that it will have a flat face
against F-3, and then trim the TE at the root so
that it will fit into the wing saddle. Tap the 1⁄16
plywood wing mount for a 6-32 nylon screw,
glue the mount in place in the fuselage, and
reinforce the joint with 1⁄4 balsa triangle stock.
Drill the screw hole through the wing and
install the 6-32 nylon wing screw. Square the
wing with the tail of the fuselage, pinning it in
place in the proper position. Drill the wing’s
LE to accept the 1⁄8-inch locator dowel.
Cowl Block: The cowl is a block of end-grain
balsa that is carved to shape. Notice that the
block is bored for the motor opening. Draw
datum lines on the front of the block and use
them as a guide for installing F-1, which is
really just a sanding guide. Glue the block in
place onto F-2 and carve and sand it to final
shape. I recommend waiting until the model is
covered to install the 1⁄16 plywood motor
mount.
Empennage: To have the necessary strength
at the stabilizer mounting, make the vertical
fin from 3⁄16 balsa. To reduce weight and
improve the appearance, block-sand the fin to
taper from 3⁄16 inch at the stabilizer slot to 1⁄8
inch or less at the tip. You should also sand it
to a symmetrical airfoil section. Cut the
stabilizer and elevator halves from 1⁄8 sheet
stock. With the pieces trial-fit together, fit the
empennage assembly to the fuselage.
Assemble the wing to the fuselage. Pin the
vertical fin in place so that it’s 90° to the wing
and aligned with the axis of the fuselage. Glue
the tail fillet blocks (made from 1⁄2 balsa stock)
in place on either side of the vertical fin, but be
careful not to glue them to the vertical fin at
this time. Remove the vertical fin and replace
it with a spacer made from scrap 3⁄16 balsa.
Carve and sand the turtledeck cap and tail
fillets to shape. Remove the spacers and slip
the vertical fin back into place, again making
sure that it’s 90° to the wing. Dry-fit the
stabilizer in place, and check to make sure that
it’s at 0° incidence relative to the bottom of the
wing. When you’re satisfied with the
alignment, glue the vertical fin in place with
thin cyanoacrylate, but leave the stabilizer
loose for the moment.
Cut the elevator hinge slots and test-fit
them. Install the music-wire elevator joiner (or
you can use a 1⁄8-inch-diameter dowel joiner if
you prefer). I found it easiest to wait and
permanently install the stabilizer after covering.
Belly Pan: With the wing mounted on the
fuselage, install the belly-pan formers on the
bottom of the wing, being careful not to glue
them to the fuselage. Dry-fit the three bellypan
stringers in place. The center stringer is
laminated from two layers of 3⁄32 x 3⁄16 balsa.
You may want to add a “keeper box” to hold
the wing screw in place in the wing.
Remove the wing from the fuselage,
leaving the screw in place in the wing, and
install the 1⁄16-inch belly-pan sheeting. Trim
and block-sand the front and rear edges flush
with the formers. Drill a 1⁄8-inch access hole
over the wing hold-down screw, and reinstall
the wing on the fuselage. Sand the joint
between the belly pan and fuselage sheeting
flush, being careful not to sand through the
sheeting.
Last Details: Install the servo mounts with
thin cyanoacrylate. Cut the battery mounting
plate from 1⁄16 balsa and install it on F-3 and F-
4, using 1⁄4 triangle stock to reinforce the
joints. Apply a strip of Velcro to the mounting
plate so that the battery pack can be secured.
I use .038 music wire for the pushrods to
keep weight to a minimum. On a model this
small, I prefer to make my control horns from
1⁄32 plywood, mortised into the surfaces for
added strength.
Finishing: The Wildcat is suitable for film
covering, but I like to finish my warbirds with
fiberglass and paint. Tissue and dope also
works well. I covered the prototype with .56-
ounce fiberglass cloth and painted it with
enamel paints. It’s a replica of the F-4F-3 that
Lieutenant “Butch” O’Hare flew when he
earned the Medal of Honor on February 20,
1942.
You can paint the canopy framing easily
using the frisket masks shown in the plans.
Make sure you protect the canopy’s inside
surface with masking tape; overspray gets
everywhere. After painting the framing,
remove the masks and glue the canopy in
place with Formula 560 or equivalent canopy
glue. Install the hardware, and you’re ready to
go fly.
Flight Testing: Be careful checking the center
of gravity (CG). I suggest that you start with
the CG two inches behind the LE of the wing
where it exits the fuselage, and adjust it to suit
your tastes. If you keep the weight near 18
ounces, the Wildcat should fly fine.
Get a capable assistant to hand-launch the
model on the first flights. It needs to be thrown
straight and level. If the launcher lobs it
upward, it’s likely to stall. Hold the wings
level and begin a shallow climb. Landings are
made with a straight-in approach, and the
model is held just off the ground until it settles
in. With the washout in the wing, the Wildcat
has forgiving stall characteristics.
I’ve been extremely pleased with this
model’s performance and handling. I use eight
cells to improve the vertical, but I spend most
of each flight at half to two-thirds throttle.
With the new HE1000 NiMH cells, endurance
is in the seven- to nine-minute range. The
Wildcat will do huge loops and Cuban 8s, and
the roll rate is surprisingly fast. Inverted flight
is solid. The Wildcat really is a joy to fly. MA
Jim Ryan
6941 Rob Vern Dr.
Cincinnati OH 45239
[email protected]
April 2004 69
Full-Size Plans Available—see page 207
Full-Size Plans Available—see page 207
70 MODEL AVIATION