Molt models Parkflyer F6F Hellcat User manual

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Parkflyer F6F Hellcat

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MOLT MODELS Background Design Philosophy
When I was first introduced to this hobby seventeen years ago I saw my first WWII warbird and
I was hooked. Several years later when I began building radio controlled model airplanes on my
own, I learned that along with the intriguing warbird looks came a plane that was usually difficult to
fly. After a few disheartening attempts with some larger glow powered warbirds I thought about
how great it would be if I could design a spirited yet forgiving warbird that could be flown in a
space the size of a soccer field. At that time the level of technology was not advanced enough to
make this a reality, but the developments in the last few years have made it possible and
economical.
The MOLT MODELS design philosophy is comprised of methods that enhance scale
appearance and all around flight performance. The first thing you’ll notice about a MOLT
MODELS kit is that the majority of wood parts, illustrations and plans are CAD based. These
items are derived from the same 3D modeling environment that the plane was designed in. My
goal is to cut down on wordy instructions and use a more visual approach that will get you from kit
to airborne in as little time as possible.

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MOLT MODELS Parkflyer F6F Hellcat
Thank you for purchasing the MOLT MODELS Parkflyer F6F Hellcat. This kit represents a true
first in parkflyer warbirds in that it possesses characteristics that make it both enjoyable to build
and more importantly, fly. I sincerely hope that you enjoy your new MOLT MODELS kit. Please
visit us at www.moltmodels.com for updates and information on future kits.
GENERAL BUILDING INSTRUCTIONS AND SUGGESTIONS
Please be sure to study the plan sheet and read through the following instructions before
attempting to build your Hellcat. Having a good idea of what to expect as you progress will cut
down on mistakes and allow you to better organize your project. Checkboxes have been provided
in front of each step that allows you to easily keep track of your work. This manual is organized
as blocks of text and illustrations that correspond to the current build section.
The Hellcat is a fully functional aileron, rudder, elevator, and throttle controlled aircraft (4
channel). You may build the Hellcat to fly with aileron, elevator, and throttle only by gluing the
rudder to the vertical stabilizer. If you decide to do this I would recommend that you leave the
landing gear off as take off and landing on a hard surface will be difficult without a rudder. I also
recommend leaving the landing gear off if you intend to fly on grass only. If you fly on a nice hard
surface, the Hellcat with all functions and landing gear is quite impressive. Do not attempt to fly
the Hellcat as a rudder, elevator, and throttle only model.
HELLCAT SPECIFICATIONS
Length: 23.5 in
Wing Span: 30 in
Wing Area: 170 in2
Flying Weight: 7.0 ~ 8.0 oz
Wing Loading: 5.93 ~ 6.77 oz/ft2
Power System: GWS DX-A IPS
Functions: Aileron, Elevator, Rudder, & Throttle
Battery Pack: 7 cell 370 mAh NiMH
7.4V ETEC or Kokam Lithium Polymer
What you will need to complete the Hellcat kit:
• Park flyer sized receiver
• Servos (Hitec HS-55 or GWS Pico/Naro) (3 Req. for 4 Channels)
• Speed Control (Castle Creations Pixie 7P or GWS ICS-50 ESC)
• GWS IPS (“A” gearing) and manufacturer recommend propeller
• Dubro Micro E/Z Connectors (5 Req.)
• Dubro Micro E/Z Link (2 Req.)
• 1/2" Dubro Micro Tail Wheel
• 1-1/2” Dubro Micro Lite Wheel (Qty. 2 required)
• 1 roll of Nelson Lite Film AKA Solite covering
• Glue, paint, and other misc. building items

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FUSELAGE BUILDING INSTRUCTIONS
 1. Pin fs2 through fs4 on the plan sheet and glue adjacent edges together.
 2. Glue formers (f1 through f9) to (fs2 through fs4) making sure they are perpendicular to
the building surface. You also need to pay close attention to the orientation of all the
formers. For instance, the notch in each former that accepts fs1 should be perfectly in line
when looking down the front of the fuselage.
 3. Align and glue fs1 to the notches of f1 though f9.
 4. Glue the wing saddle ws to f3 through f6 of the fuselage half.
Figure 1

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 5. Glue all 3/32" SQ balsa stringers to both fuselage side assemblies noting the end points
of each stringer in Figure 2.
 6. Glue the elevator pushrod exit ps to the fuselage side shown in Figure 2. When each
fuselage half is removed from the building board they may warp ever so slightly, this is due
to the stress the 3/32" SQ balsa stringers introduce on the structure. Do not be concerned,
as the two fuselage halves will straighten each other out when they are joined together.
 7. Glue the fuselage halves together. Be sure to fit the plastic cowling to the front of the
fuselage before covering. The cowling is designed to have a tight friction fit to reduce the
weight of components that might be necessary to hold it on. Sand the circumference of the
front of the fuselage until the plastic cowling has a nice tight fit. The plastic cowling should
slide about 1/8” to ¼” over the front of the fuselage.
Figure 2

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 8. Install the cockpit floor cp by gluing it to fs2a, f4, f5 and the 3/32" SQ balsa fuselage
stringers. Refer to Figure 3 for cp's location.
 9. Install the servo tray st by gluing it to f3/f3a and the 3/32" SQ balsa fuselage stringers.
Refer to Figure 3 for st's location.
 10. Build the battery box using the laser cut balsa parts bb1 through bb4 per Figure 3.
When the battery box is complete glue it to the fuselage formers f2/f2a and f3/f3a per
dimension shown in Figure 3.
 11. Glue the 1/4"x1/2" balsa wing mounting block to the fuselage formers f5 and f6. Glue
the 1/4" balsa triangle wing mounting support gusset to the 1/4"x1/2" balsa wing mounting
block and fuselage former f5. This is illustrated in Figure 3.
 12. Laminate the (3) 1/16” thick precut 5/16”x2-7/8” plywood pieces to construct the GWS
IPS mounting stick. Glue the laminated GWS IPS mounting stick to formers f2/f2a and
f3/f3a. This is illustrated in Figure 3.
 13. Remove the section of former f4 shown in Figure 3.
Figure 3

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 14. Install the elevator and rudder servos and GWS IPS as shown/described in Figure 4.
Figure 4

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 15. Build the elevator and rudder pushrods as shown on the plan page.
 16. Install the thin plywood control horns in the receiving slots in the rudder and elevator
after these control surfaces have been covered. Note this is after the horizontal and
vertical stabilizers have been built.
 17. Refer to Figure 5 for the routing and connection of the pushrods to the servos, elevator
and rudder.
 18. The control rods at the servo end are attached to the servo with the adjustable Dubro
E/Z connector. The control rod wires at the control surface ends are attached by the 1/32”
music wire that passes through the holes in the control horns. Be sure the wires passing
through the control horns extend about ¼” so that the Dubro E/Z Link will retain the control
rod to the control horn. This is illustrated in Figure 5.
Figure 5

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WING BUILDING INSTRUCTIONS
Wing Center Section
 1. Cut and pin the bottom 1/8"x1/4" balsa main spar, 1/8"x1/4" balsa servo mounting rails,
3/32" SQ balsa rear spar, wm2, and the 1/16"x1/4" balsa trailing edge stock to the wing
plans on the plans sheet. Note the gap between the servo mounting rails was set per the
dimensions of a Hitec HS-55 servo. You may need to modify the location of these two rails
if you plan to use a different servo manufacturer.
 2. Build the landing gear support rib subassemblies using ribs R4, R4a, and R4b. Note the
differences in each subassembly by referring to Figure 6.
 3. Fit, and then glue R1,R2, R3, R4, R4/R4a/R4b subassembly, and R5 ribs to the
connecting spars and adjacent wood parts making sure that each rib is perpendicular to the
building surface.
 4. Glue the top 1/8"x1/4" balsa main spar to the center section ribs R1 through R5. Note
that this spar must be "cracked" in the center to allow it to follow the taper of the wing's
design. Flood this crack with CA glue after it is glued to the notches of ribs R1 through R5.
 5. Glue the top 3/32" SQ balsa rear spar to ribs R1 through R5. Study the enlarged R5 rib
illustration in Figure 6 for a better look at the spar location in R5.
Figure 6

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 6. Glue wm3 to wm2, ribs R1, and trailing edge stock. The hole in wm3 is aligned to the
hole in wm2 as shown in Figure 7.
 7. Glue in the laser cut shear webs sw1 through sw5. Note that the grain of each shear
web runs perpendicular to the building board. The hole in sw1 should be oriented so that it
is closest to the bottom of the wing. This hole accepts the wing-mounting dowel.
 8. Glue the leading edges le1 and le2 to the front of each rib. Align the leading edges so
that they are centered on the front of the ribs.
Figure 7

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Wing Tip Sections (follow steps 9 through 18 for both outer wing panels)
 9. Cut and pin the bottom 1/16"x1/8" balsa tip spar, 3/32" SQ balsa bottom rear spar, g1,
and the 1/16"x1/4" balsa trailing edge stock to the wing plans on the plan sheet. Study
Figure 8 before proceeding. The bottom spars only extend to the inside of Rib R5.
 10. Fit, then glue R6 through R11 ribs to the connecting spars, and adjacent wood parts
making sure that each rib is perpendicular to the building surface. DO NOT glue any part
of the outer wing panels to the center wing section. g1 should only be glued to the
1/16”x1/4” balsa trailing edge stock at this point of the build. The outer wing panels will be
glued to the center wing section after the dihedral angle has been set.
 11. Glue the top 1/16"x1/8" balsa tip spar and top 3/32" SQ balsa rear spar to ribs R6
through R11. Note the overlapping dimension for both the top 1/16”x1/8” balsa tip spar and
3/32" SQ balsa rear spar shown in Figure 8.
 12. Glue a9 to ribs R8 through R11, then glue a7 to a9 and R9.
 13. Glue wt to R11 along with its support gussets g2 and g3.
 14. Glue in the laser cut shear webs sw6 through sw8. Note that the grain of each shear
web runs perpendicular to the building board.
Figure 8

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 15. Unpin each outer wing panel and "block up" each tip to the dihedral dimension shown in
figure 9. At this point glue the outer wing panel spars to the center wing section spars as
shown in Figure 9. Use a 90 deg triangle to make sure the outer panels are aligned over
the plans.
 16. Glue the leading edge le3 to the front of ribs R5 through R11. Align le3 so that it is
centered on the front of the ribs.
 17. Glue the top 3/32" SQ balsa front spar across the entire wing.
 18. Glue the 1/8" wing-mounting dowel to sw1 and le1 per the plan sheet and Figure 9.
Figure 9

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 19. The aileron servo installation is accomplished with the mounting screws provided by the
servo manufacturer and left up to the builder’s preference. Fasten the servo to the 1/8" x
1/4" balsa servo mounting rails. I do not recommend the use of the rubber grommets that
are included with the servo.
 20. Route the yellow sleeve (tubing) through the wing as shown in Figure 10. Be sure to
make the tubing run through each hole in the ribs so that it is not "kinked". If the tubing is
not a smooth continuous run, it might create additional friction with the control cable and
make the aileron servo work harder to control the plane. When you are satisfied with the
tubing fit, glue the tubing to the ribs it passes through. Trim the tubing flush with the inside
of ribs R1. Next, slide the 1/32" braided cable inside the tube as one continuous run. Just
slide the cable inside the tubing and through the Dubro E/Z Connector on the aileron servo.
Make sure that the aileron servo arm is positioned so that the cable does not bind with the
tubing and EZ Connector.
 21. Build the ailerons per the plan sheet.
Figure 10

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VERTICAL STABILIZER AND RUDDER BUILDING INSTRUCTIONS
 1. Pin vs1 through vs10 on the plan sheet and glue adjacent edges together where
applicable.
 2. Next cut and glue each of the remaining 3/32” SQ balsa sticks to complete the plans.
Note that each 3/32” SQ balsa stick is a square cut, a new straight razor will make short
work of these.
 3. The vertical stabilizer and rudder are complete at this time. If you do not plan to use the
rudder on your Hellcat you can glue it the vertical stabilizer.
HORIZONTAL STABILIZER AND ELEVATOR BUILDING INSTRUCTIONS
 1. Pin hs1 through hs10 on the plan sheet and glue adjacent edges together where
applicable.
 2. Next cut and glue each of the remaining 3/32” SQ balsa sticks to complete the plans.
Note that each 3/32” SQ balsa stick is a square cut, a new straight razor will make short
work of these.
 3. Join the two elevator halves with the 3/32” SQ hardwood stick provided in the kit. Do not
use 3/32” SQ balsa here as this will most likely lead to structural failure.
 4. The horizontal stabilizer and elevator are complete at this time.

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WING MOUNTING INSTRUCTIONS
 1. Mounting the wing to the fuselage on the Hellcat is pretty straight forward since the 1/8”
wing-mounting dowel is positioned in the wing and the hole in the fuselage formers f3 and
f3a receives the wing-mounting dowel.
 2. With the wing inserted into the fuselage formers and laying flat in the wing saddle, adjust
the wing so that the distance between the rear of wing tips and rear of fuselage are the
same. When this is achieved, the wing is square with the fuselage. You may need to sand
the leading and trailing edge of the wing to get a good fit. Take your time here, as this is an
important part of the plane.
 3. Using the holes in wm2 and wm3 to align the drill bit, match drill a hole through the
1/4"x1/2" balsa wing mounting block. The diameter of the drill bit should match the inner
diameter of the threaded brass insert. See Figure 11.
 4. Thread the threaded brass insert into the 1/4”x1/2” balsa wing mounting block until it is
flush with the top of the wing-mounting block. Wick a small amount of CA glue around the
outer edge of the brass insert and wing-mounting block to secure it. Be careful not to let
the CA come in contact with the inner machine threads of the brass insert.
 5. Attach the wing with the supplied nylon bolt and the wing is officially mounted.
Figure 11

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UNDER WING FILLER SECTION BUILDING INSTRUCTIONS
 1. Fasten the wing to the fuselage.
 2. Pin and glue the belly formers bf1 through bf4 on the bottom of the wing. The order of
the belly formers is shown in Figure 12. Note the distances between the belly formers
bf1/bf4 and fuselage formers f3/f3a/f6 shown in figure 12. These gaps are necessary to
make the wing removable.
 3. Glue all 3/32" SQ balsa stringers to the belly formers.
 4. Glue wm1 to bf3, bf4 and adjacent 3/32” SQ balsa stringers.
 5. Create a small tube from scrap paper the same diameter as the hole in wm1. Insert the
paper tube into the hole in wm1 and align it with the holes in wm2 and wm3. Glue the
paper tube to wm1, wm2, and wm3. It will not hurt to soak the tube with thin CA to make it
more durable. This tube will aid in the alignment of the nylon wing bolt.
Figure 12

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GENERAL FINISHING INSTRUCTIONS AND FLIGHT RECOMMENDATIONS
 1. The battery is held inside the battery box with Velcro. Orient and glue the Velcro to the
top and bottom of the battery box so that it will create a “belt” to keep the battery from
coming out of the battery box in flight as shown in Figure 13. If you chose to use a longer
battery pack that is longer than the depth of the battery box you will need to make the hook
component of the Velcro longer.
Figure 13

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 2. Trial fit the horizontal and vertical stabilizers before covering. Perform any necessary
sanding to achieve a good fit.
 3. Cut out and fit the plastic canopy and cowling before painting and covering the fuselage.
Perform any necessary sanding to the fuselage to achieve a good fit. The cowling slides
over the front of the fuselage and should have a snug fit.
 4. Sand the entire model smooth and round the wing leading edge to match the shape of
the airfoil.
 5. If applicable, bend the landing and tail landing gear to the required shape by using the
supplied landing gear wire bending templates as shown on the plan sheet. Install the main
landing gear into the receiving portion of the R4/R4a/R4b subassembly with the wire
oriented so the wheels are facing the wing tips. Install the bent tail landing gear into the
receiving portion of the two-fs3 formers that are on the bottom rear of the fuselage. Install
the Dubro main wheels and tail wheel at this time. The main wheels are held on with the
included hemispherical black plastic wheel collars. These collars are attached with thin CA
glue to the main landing gear wire, be careful not to glue the wheel to the landing gear wire.
The tail wheel is held on with a scrap piece of Sullivan Flexible Tubing (left over from
aileron tubing). The scrap Sullivan Flexible Tubing is attached with thin CA glue to the tail
gear wire, be careful not to glue the wheel to the landing gear wire. This is illustrated in
Figure 14. (Note, the Dubro wheels may have to be drilled out to fit the landing gear wire)
Figure 14

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 6. Cover and paint your model. I recommend Nelson Lite Film AKA Solite. These
coverings can be purchased from www.toddsmodels.com . Scale paint schemes can be
found on www.rcgroups.com and the World Wide Web.
 7. Glue the control horns in the ailerons, elevator, and rudder.
 8. I recommend Scotch #600 3/4" brand tape for hinges. Run the tape down the top of the
entire control surface with half of the tape on the moving surface and the remaining half on
the stationary surface. Leave about a 1/32” to 1/16” gap between the control surface and
stationary surface to assure you have enough movement.
 9. I recommend you set the amount of control surface throw to the following settings…
Aileron: 3/8" either direction, Rudder: 1/2" either direction, Elevator: 3/8" either direction
 10. With everything installed in your Hellcat to make it flight ready, be sure the plane
balances on the range shown on the side view of the first plans sheet. After your test flight,
feel free to move the balance point to get the desired performance. The range shown is
very conservative.
 11. With proper balance you’re ready for your first flight with the Hellcat. On the first flight,
get the Hellcat high enough that you can let off the control sticks to see what it does without
risking a crash. The Hellcat is a very forgiving model and depending on the equipment you
chose to finish it, you may have to trim it out as necessary.