Approach Engineering AH-1F Cobra Electric User manual

APPROACH ENGINEERING
WWW.APPROACHENGINEERING.COM
PROUDLY MADE IN THE USA
AP101
AH-1F COBRA 600

AH-1F COBRA 60 PAGE # 2
APPROACH ENGINEERING
AH-1F 60 MECHANICS
1.0 Purpose
To establish a process that ensures control and standardization in the manufacturing of AH-1F Cobra for use with 60 size
mechanics. P/N AP-101.
2.0 Tools Required
Note: (A) denotes tools required for assembly and
(T) denotes tools required for testing.
Basic Hand Tools (A, T)
Epoxy 30 Minute, JB WELD (A)
Cyanoacratulate (CA) (A)
3.0 Reference Documents
Plans for AH-1F Cobra Plan Sheet (A, T)
4.0 Attachments
5.0 Introduction
1. WARNING This aircraft is not a toy. It is capable of serious bodily harm and property damage. Every precaution
must be taken to properly build this kit and install all radio components. It is your responsibility alone to ensure all
safety steps are taken outlined in the Academy of Model Aeronautics safety codes. If this is your first time building a
aircraft kit it is highly recommended that you find experienced help for the first flights. Consult your local hobby shop
or write to the AMA for further guidance.
Academy of Model Aeronautics
5151E. Memorial Drive
Muncie, IN 47302 [phone]
2. Please inspect all parts before building. If any parts are broken or missing please feel free to call or write for replace-
ment. All instruction manual photos are included with the CD along with other scale documentation pictures to ease in
finishing. If a step or photo appears unclear to you inspect the CD for additional photos with different views to aid in
assembly If you have any questions, comments, or improvements please call or write to:
Approach Engineering LLC
Ridgecrest, CA. 93555
3. We as manufacturer can provide you with assistance and a top quality kit and instruction manual. When built light,
straight, and true you will have a model that flies as well as it looks on the ground. However the finished product de-
pends on the quality built into it. We can not guarantee the flight performance. Take your time and read all instruc-
tions carefully before and during construction.
4. During the assembly procedure the use of the term CA refers to thin CA glue and CA+ refers to medium viscosity glue.

AH-1F COBRA 60 PAGE # 3
APPROACH ENGINEERING
AH-1F 60 MECHANICS
6.1 Assemble the side frames, (S-1, S-2, S-3, S-4) over a piece
of wax paper. Refer to the full size plans and the included pic-
ture for assembly. Punch out the four 3/32” fuselage side pieces
for each side. The provided tabs allow for proper alignment and
assembly of the fuselage sides. Build a right and a left taking
note of the triangle stock reference lines. These will aid in the
installation of the triangle stock. Using the notches provided
assemble and glue with CA the two fuselage sides.
6.2 Place the completed assemblies of the fuselage side frames
and lay them out to build a right and left half. Have the triangle
reference lines up so that they will be on the inside of the as-
sembly. The notches in the fuselage for F-3 and F-4 will line up
with the notches in the fuselage doublers. Using 30 minute ep-
oxy glue on the fuselage doublers. Set aside and allow to dry.
6.3 Take note of the laser labeled 3/4” triangle stock reference
lines on the inside fuselage surface. Cut and glue with CA the
3/4” triangle stock to match the reference lines. Complete for
both left and right sides.
6.4 Glue F-3, with the text and curved edge, and F-4 into the
notches of the fuselage doublers to make the fuselage box.
6.5 Glue 3/4” balsa triangle stock along the lower edge in front
of F-2 so that it extends past the front of the fuselage sides by
about 1/8” to be sanded off later. To aid in bending you may
want to saw cuts down to about 1/8” from the fuselage side.
6.6 Punch out former F-1 from the 1/8” light ply. Using CA
glue to the front of the fuselage so that the notches fit in the
fuselage sides. Sand the triangle stock flush with F-1.
6.0 FUSELAGE ASSEMBLY
Align Notch Openings
F-3
F-4
3/4” Triangle Stock
Saw Cuts
Notches Sand Flush
3/4” Triangle Stock

AH-1F COBRA 60 PAGE # 4
APPROACH ENGINEERING
AH-1F 60 MECHANICS
6.7 Punch out the 1/8” Light ply former F-2. Glue it behind F-
1 so that it is flush with the canopy edge.
6.9 Glue with epoxy the 1/4” light ply fuselage base so that it
is lined up with the back end of F-4 and front of F-3.
6.11 Punch out the 1/8” light ply transmission back plates and
canopy backer plate. Sand the outside corner edge to relieve the
corner so that the transmission and canopy will slide in easier.
Making sure not to get glue inside the canopy teeth area glue
TBT so the notch lines up with F-4. Glue the CBT in front of
the transmission backing. Complete for both sides.
6.8 Turn the fuselage assembly over. Using epoxy glue the
3/4” square hardwood landing gear blocks into the notches of
the fuselage doublers. The holes in the fuselage side should line
up with the landing gear mount holes.
6.10 Punch out the 1/8” light ply FD-2. Using CA glue in
front of F-2 and notched into F-1. Complete for both sides.
NOTES:
6.0 FUSELAGE ASSEMBLY
FD-2
TBT
CBT

AH-1F COBRA 60 PAGE # 5
APPROACH ENGINEERING
AH-1F 60 MECHANICS
7.1 Punch out the two 1/8” lite ply vertical fin supports and two
tail rotor tube supports (TSR) and one trailing edge former (TE-
2). The rounded edge of the tail rotor tube support faces fore-
word. Glue TE-2 in the upper slot and the two TSR supports in
the mid and lower slots.
7.3 Glue ¼” triangle stock to the inside edge of the vertical fin
supports and the tail rotor frame base.
7.5 Roughen the tail rotor tube surfaces with sand paper to
increase the strength of the glue bond.
7.2 Glue the vertical fin assembly into the tail rotor frame base
(TFB).
7.4 Referring to the plans for proper placement, glue in the tail
rotor drive shaft tube supports at 5.2” and 2.5” inches from the
bottom of the tube. The last support will be flush with the bot-
tom of the tube. Mark up a scrap piece of balsa at the correct
dimensions to help insert the supports at the right distances.
7.6 Using epoxy glue the tail rotor tube so that the bottom sur-
face is flush with the lower surface of the bottom tail rotor tube
support.
7.0 VERTICAL FIN ASSEMBLY
Flush with lower
surface

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APPROACH ENGINEERING
AH-1F 60 MECHANICS
7.7 Trial fit the leading edge supports (TSF) to ensure proper
fit and contact with the tail rotor tube. Using epoxy, glue the
tail rotor leading edge supports in the notches and to the tail
rotor tube.
7.9 Apply epoxy to the inside surface of the tail rotor drive
shaft supports. Slide the tail rotor drive shaft starting from the
bottom up to the top surface of the upper drive shaft washer.
7.11 Apply ¼” triangle stock along the edge of the lower sur-
face of the tail rotor frame to the fuselage sides. Do not have the
triangle stock extend past the 3/4” triangle stock.
7.8 Slide the tail rotor pushrod outer housing through the holes
in the leading edge supports so that it so that it extends past the
upper leading edge support. You can trim later as necessary to
fit your control linkage setup.
7.10 Glue the tail rotor tube assembly to the fuselage assembly
by aligning the notches in the fuselage sides. Trim the triangle
stock as necessary to clear the pushrod tube.
7.12 Make two sets of the tail boom filler blocks by gluing
two (FBS) together. The tail boom filler blocks are made to fit
on the lower surface and back side of the tail rotor frame for
extra support and the outer profile will match the fuselage pro-
file. Using CA glue flush with the lower tail rotor frame sur-
face, back side of the tail rotor frame, and fuselage side surface.
7.0 VERTICAL FIN ASSEMBLY
TSF
Align in the notches
2 Sets of 2

AH-1F COBRA 60 PAGE # 7
APPROACH ENGINEERING
AH-1F 60 MECHANICS
7.13 Sand the tail filler block middle (FBM) at a angle and
trial fit to the remaining gap in the tail boom end. The block
should be tapered to a edge on the trailing side and the full ¼”
on the leading side.
7.15 Using the 3/32” x 6” wide x 12” long balsa, cross sheet
the remainder of the lower tail boom starting from the ¼” light
ply base to the end of the tail boom. Note: make sure not to
build a twist into the tail boom as you apply the cross sheeting.
7.17 Sand the horizontal fin to the desired shape. Note: the
real aircraft has a flat top and a rounded lower surface. This
may pull the nose up in foreword flight and it is up to the mod-
eler which shape to sand.
7.14 Glue the tapered filler block into position when properly
fitted in place.
7.16 Making two sets glue the upper and lower horizontal fins
together, from the ¼” balsa, making sure to make a right and a
left.
7.18 Glue the ¼” x ¼” x 7” spruce in the notch of ONE of the
horizontal stabilizers.
7.0 VERTICAL FIN ASSEMBLY
Tapered Edge
Leave 1/4” thick on this end
Filler Block

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APPROACH ENGINEERING
AH-1F 60 MECHANICS
7.19 Note: depending on your desired finishing technique you
may want to omit permanently gluing the horizontal fins on at
this time to aid in sanding and finishing. Slide the spruce notch
in through the holes and have the fin tab notch fit in the side of
the fuselage. Trial fit the other fin and when satisfied glue with
CA+.
7.21 Assemble the servo mounting rails by punching out the
two 1/8” light ply supports labeled Approach Engineering. Pull
out the two 1/4” x 1/2” spruce servo rails and slide into place.
Do not glue at this time until you have properly fit the assembly.
7.23 Punch out the 1/4” balsa pushrod support. Glue the sup-
port to the pushrod outer tubing so that it properly lines up with
your servo position. Using scrap balsa properly secure the re-
mainder of the pushrod tube to the lower and side surfaces so
that there is as little movement as possible.
7.20 Glue ¼” by ¼” by 3” balsa along the tail rotor drive shaft
tube to the lower sheeting. Make sure to align the drive shaft as
straight as possible. Apply glue between the supports and the
tail rotor drive shaft.
7.22 Slide the assembly just behind F-4 between the fuselage
doublers and sitting on top of the 3/4” triangle stock along the
lower surface. Temporarily install a servo to help determine
proper pushrod placement.
7.24 Punch out the 1/8” light ply former F-5. Trial fit into
place behind F-4 in the transmission area. This is used to
square up the tail and to make more rigid. Fit in place with the
“Front” text facing toward the front of the aircraft. Fit into
notches and make sure it is flush with the upper fuselage edge.
in the fuselage side and glue in place.
7.0 VERTICAL FIN ASSEMBLY
Scrap Balsa
Pushrod Support
Notch

AH-1F COBRA 60 PAGE # 9
APPROACH ENGINEERING
AH-1F 60 MECHANICS
8.1 Sand the face of the fuselage assembly flush with F-1.
Glue on the two TSU back plates (TSU-B) together. Position
the notch toward the bottom of the fuselage and glue flush with
the bottom and sides of the fuselage nose.
8.3 Glue the two TSU bottom pieces, TSU-L, together. Mark
a line 1/2” from the back edge as a sanding guide. Sand the
TSU bottom pieces from the line at a constant angle to about
3/32” up from the rounded edge as shown in the picture.
8.5 Glue the five nose blocks together starting from NB-1 on
the bottom to NB-5. Make sure that the back edge is flush and
forms a block. Glue the assembly to the top of the TSU back
plate against F-1. Sand the nose blocks flush with the top of
the cross sheeting on the fuselage nose. Sand a small radius on
the front of the nose block and the sides flush.
8.2 To aid in sanding draw lines on the lower surface and the
fuselage side ¾” from the sheeting. When sanding make a even
transition from line to line. Sand the fuselage corners to their
finished rounded shape. Sand rounded corners on the three out-
side edges of the TSU back plate.
8.4 Glue the TSU bottom pieces into the notch in the TSU
back plate.
8.6 Make two sets of three T-2’s glued together. Sand the
front of the TSU to the desired finished rounded shape by
rounding the corners. Glue one T-1 between the two TSU as-
semblies and one T-3 on each side and sand the glued assembly
to the desired finished shape.
8.0 NOSE AND TSU (TELESCOPING
SIGHT UNIT) ASSEMBLY
Fuselage Bottom
Back Edge Flush
3 T-2’s
T-1 T-3
T-3

AH-1F COBRA 60 PAGE # 10
APPROACH ENGINEERING
AH-1F 60 MECHANICS
9.1 Punch out the 3/32” balsa canopy sides and the 1/8” lite
ply canopy guide teeth (CGT). Lay out the parts to build a right
and a left canopy side. Position the canopy guide teeth so that
the teeth extend past the bottom surface and match the bend
with the sides and equal 1/8” from ends. Glue with CA. cut
1/4” triangle stock (TRI-4) to fit between C-1, C-2, and C-3.
Line up the triangle stock with the printed reference lines.
9.3 When the glue has dried run a bead of glue up the remain-
der of C-1, C-2 and C-3. Using masking tape pull the canopy
sides to conform with the curve of C-1, C-2 and C-3. Sand the
top of the triangle stock flush with the canopy sides for cross
sheeting.
9.5 Carefully cut out the canopy top surface CT-1 from the
3/32” balsa. Glue on the top surface so that the front edge lines
up with the bend in the center canopy. Sand the canopy surface
flush with the center canopy surface.
9.2 Starting at the base, glue only 1” up on both sides of C-1,
C-2 and C-3 to the fuselage side and guide teeth. This will help
to build a straight canopy by first assembling it as a “box” struc-
ture.
9.4 Turn the canopy over and glue C-4 into place in the
notches in the canopy guide teeth. The bottom surface should
be flush with the edge of the canopy guide teeth.
9.6 Cut out the canopy center section CT-2 and complete the
step as earlier. Sand the front and rear edges flush as before.
Cut out the front canopy edge, CT-3 from the 3/32” balsa.
Align the front edge with the front of the canopy. Glue in place
with CA. When set sand the
back edge flush with the top
surface of CT-2.
9.0 CANOPY ASSEMBLY
Triangle Stock
extends past
upper edge.
Sand Flush
C-4
Sand this edge
flush
CT-2
CT-3