Approach Engineering AH1 "W" Cobra User manual

AH1”W” COBRA
DESIGNED FOR THE SWIFT 16
APPROACH ENGINEERING
WWW.APPROACHENGINEERING.COM

AH-1W COBRA—ELECTRIC Page 2
APPROACH ENGINEERING
1.0 Purpose
To establish a process that ensures control and standardization in the manufacturing of AH-1W Cobra for use with Swift 16
electric mechanics.
2.0 Tools Required
Note: (A) denotes tools required for assembly and
(T) denotes tools required for testing.
Basic Hand Tools (A, T)
Sanding block and paper (A)
Dremel Tool (A)
Epoxy 30 Minute (A)
Cyanoacratulate (CA) (A)
3.0 Reference Documents
Exploded View Plans for AH-1W Cobra (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
Ridgecrest, Ca. 93555
www.approachengineering.com
3. We as the kit 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
depends 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-1W COBRA—ELECTRIC Page 3
6.1 Locate fuselage side pieces S1, S2 and S3. Glue these
together to make a left and right fuselage side. Add triangle
stock as shown.
6.2 NOTE: before beginning, read through to step 6.4 and
determine which assembly procedure you will use. Punch out
the two FB1 side doublers and glue in place, taking care to align
the bulkhead slots. On both sides, add the forward ply doublers
FPD as shown, notch forward.
6.3 Install and glue bulkheads F3, F4 and F5 onto FB2 and
FB3, then glue and insert into a fuselage side, ensuring that all
the pieces are aligned and straight. Install the hardwood chassis
mount blocks to the inside of bulkheads F4 and F5. Install the
second fuselage side.
6.4 An alternate method is to assemble the fuselage center as a
box. Fit the F3, F4 and F5 bulkheads to the deck pieces FB2 and
FB3. Attach sides FB1, then glue each side to it’s proper fuse-
lage side. Add chassis support blocks before final glue.
6.5 Temporarily position your mechanics in the enclosed
Fuselage and mark mounting points on the mechanics mounts.
6.6 Drill holes in the mechanics mounts on the marked posi-
tions with a 9/64” drill bit. Press in the four 4-40 blind nuts on
the bottom side of the mechanics mounts.
6.0 FUSELAGE ASSEMBLY
Hardwood blocks
Below plywood
triangle stock
NOTE: alternate
procedure listed
below in 6.4
NOTE:
alternate
procedure
This picture is for reference only—
some parts are removed for clarity
This picture is for reference
only—some parts are
removed for clarity

AH-1W COBRA—ELECTRIC Page 4
6.7 Turn the fuselage over and add the 1/4” square corner
stock as shown. Epoxy in the forward landing gear support
block, and the rear gear doublers making sure that the holes
align with the holes in the fuselage sides. Then glue the 1/4”
Ply Doublers over that 1/8th inch Ply to strengthen the
landing gear supports. Make sure to align the holes.
6.9 Find the belly skin BS1 and hatch. Glue the hatch frame
(1/8” Ply , Use 1/8th ply scrap for filler pieces) to the bottom of
the hatch, then install the magnet bases on both the frame and
the hatch. Fabricate a small catch on the front of the hatch using
scrap 3/32” material. Glue BS1 to the bottom of the fuselage. A
small UHF antenna will later be added to the hatch to pull it
open.
6.11 Glue together the 3 upper nose blocks UNB and 3 lower
nose blocks LNB as shown. Glue them to the front of the fuse-
lage as shown. Then glue the TSU shim TUS to the bottom of
the upper nose blocks as shown.
6.8 Now install 3/32” cross-grain sheeting from bulkhead F3
to bulkhead F4. The sheeting should only cover half of F4, leav-
ing a ledge for the next bottom skin sheet, BS1.
6.10 Begin forming the nose by adding the nose
floor sheet, NS1. Wet the nose pieces to make them
contour to the shape, while adding bulkheads F1 and
F2. The two bulkheads are tied together by the for-
ward brace FBR. Continue with 3/32” sheeting until
the nose is complete.
6.12 Assemble the four nose chin blocks NCB. Glue together
three TSU lower mounts TMT. Glue them to the front side of
bulkhead F1.
6.0 FUSELAGE ASSEMBLY
TSU shim
NS1
gear side doublers
1/8th Inch Ply then
Epoxy the 1/4th ply
doublers over this.
Hatch area- leave open
NCB

AH-1W COBRA—ELECTRIC Page 5
6.13 Punch out the two 1/8” light ply vertical fin supports
VFS and two tail rotor tube supports (TSR). The rounded edge
of the tail rotor tube support faces foreword. Glue the two TSR
supports in the mid and lower slots on one side only.
6.15 Assemble each pulley idler assembly by first pushing the
1/8” shaft through the bearings. Place one bushing on each side
so that the end of the shaft is flush with both sides. Complete for
both idlers. NOTE: plastic housing ends must be drilled open to
make clearance for the shaft width, otherwise the shafts will be
too long to fit into the tail.
6.17 Punch out the 1/8” ply tail rotor frame base (TFB).
Note: the base has a break out tab that will be removed later at
the front of the part. Do not cut at this time. Slide the vertical
fin supports into the base and glue with CA+.
6.14 Assemble the two belt idlers pulleys as shown. The
chamfered edge of the pulleys should face inward to help guide
the belt.
6.16 Place the toothed idler assembly in the lower hole and the
smooth idler in the upper hole. Take the supplied belt, not the
one with your mechanics, and place it between your idlers so
that the teeth are facing toward the toothed idler. Glue the other
vertical fin support to the tube supports. You may place a small
amount of glue on the outside of the bushings to help hold them
in place.
6.18 Glue on the 1/8” ply side pulley doublers (SPD) to the
outside of each pulley assembly by aligning the edges.
6.0 FUSELAGE ASSEMBLY
Bearings 2 each
Guide Washers 2 each
Note direction of teeth
Smooth Idler
Tooth Idler
Bearings
TSR

AH-1W COBRA—ELECTRIC Page 6
6.19 Cut out the 1/8” ply trailing edge former (TE-2) and glue
it into the notches provided on the top of the vertical fin assem-
bly.
6.21 Cut out three tail rotor tube leading edge supports (TSF)
from the 1/8” ply. Using 30 minute epoxy glue to the vertical
fin supports and the tail rotor tube.
6.23
6.20 Pull out the larger diameter, longer, tail rotor tube. Using
30 minute epoxy glue to the vertical frame so that the bottom
edge is flush with the bottom surface of the bottom tail rotor
tube support and the vertical cuts are at the top of the fin assem-
bly..
6.22
6.24 Glue the completed assembly into the notches provided
in the fuselage side. The telescoping tube fits inside this epoxied
tube, with the clamp located at the top.
6.0 FUSELAGE ASSEMBLY
Bottom edges line up.
TSF
Telescoping tube
clamp goes here

AH-1W COBRA—ELECTRIC Page 7
6.25 Once the nose blocks are sanded to the proper contour,
dremel out the bottom of the nose blocks where they meet bulk-
head F3. Using the existing oval hole in F3, form an air intake
for the battery compartment.
6.27 Find the cheek corner blocks CCB and glue them to-
gether into two stacks as shown. Locate and install the cheek
cowl blocks CCW, and chin cowl block CWB after taper sand-
ing to the
proper
shape.
6.29 Glue together the tail blocks TBL and fit them into the
end of the tail, as shown.
6.26 Install the balsa canopy retainer side rails CRR.
Balsa side rails CRR
6.28 Glue together the TSU blocks and gun turret blocks
TUR. Use these assemblies to aid in placing the chin and cowl
blocks. Do not glue them into place at this time, wait until after
finish and paint, then final assembly of the gun.
6.0 FUSELAGE ASSEMBLY
Corner blocks CCB
Cheek and chin blocks
TUR blocks
TSU blocks
tail blocks here

AH-1W COBRA—ELECTRIC Page 8
6.31 Before adding the fuselage top and bottom sheeting, in-
stall the rudder control nyrod in the fuselage. It must be routed
so it is free of binding, and does not contact the belt drive or
pulleys.
6.33 Install the lower fuselage sheeting LFS to en-
close the bottom of the fuselage.
6.35 Before sheeting the top of the fuselage, clip out this for-
ward cross brace on the tail base. This is necessary to provide
belt clearance.
6.32 Using scrap plywood secure the nyrod away from con-
tacting the pulleys.
6.34 Working from the open top of the fuselage, install nyrod
supports as required to position the nyrod so it will terminate in
line with your servo arm.
6.36 Add the upper fuselage skin UFS. At this point it is
advisable to install the tail drive gearbox as well.
6.0 FUSELAGE ASSEMBLY
upper skin
Add gearbox
Telescoping tube and clamp scrap plywood guard for NYROD

AH-1W COBRA—ELECTRIC Page 9
7.1 Install a piece of 5/8” triangle stock for the vertical tail
leading edge. Make a paper template for the correct shape of
the left and right skins. Using the template cut out the sheet
stock and glue in place. Wetting the wood makes it bend easier.
7.3 Canopy frame construction begins by placing the canopy
frame lower frames CLF in place on the canopy side skins CSS.
Note that the CSS has a small additional piece that goes in front.
Also test fit into your fuselage to ensure the proper curvature in
the front. Glue the mid and read
bulkheads in place as shown.
7.5 Do not glue the rear of the upper frames just yet. They will
fit into the doghouse lower frame when it is installed, in a later
step.
7.2 Before proceeding further, adjust the tail housing height to
1 5/8” . This will provide the proper position for setting the belt
tension.
7.4 Locate the canopy side frames CSF, canopy center rails
CTR, canopy top skin CTS, canopy middle bulkhead CMB and
canopy rear bulkhead CRB. First glue the two bulkheads to the
canopy side skins CSS. . Place the canopy front bulkhead CFB
in place and glue the side frames, making sure the bulkhead is
lower than the nose so the
canopy fits flush.
7.6 Continue the upper fuselage by gluing the transmission
lower rails to the trans side skins TSS.
7.0 FUSELAGE ASSEMBLY
1 5/8”
Telescoping section
clamp
CSS

AH-1W COBRA—ELECTRIC Page 10
7.7 Add transmission housing bulkheads TB1, TB2, TB3 and
TB4 to the trans housing skins.
7.9 Glue spacer EXH9 to the back of EXH3, then install the
two EXH7 and 8 pieces to the back of EXH3. Add block
EXH10 to the rear of this assembly, then add 1/4” stock cap to
the top edge as shown.
7.8 Assemble the exhaust frame by punching out EXH1,
EXH2, EXH3, EXH4, EXH5, EXH6. First place EXH2 and
EXH5 between EXH 3 and 4. Then place this assembly on top
of EXH1. EXH 6 then goes on top.
7.10 The lower portion of the housing can be filled with some
scrap 1/4” balsa stock and sanded to the contour. Also note that
now is a good time to apply wood sealer and primer to the aft
portion of the housing, since the exhausts will cover this part
making it impossible to seal later.
7.0 FUSELAGE ASSEMBLY
7.11 Prepare to sheet the engine cowl sides by add-
ing the square basswood stock as shown.
7.12 Assemble the doghouse structure by first plac-
ing the trans top skin TTS in place at the aft and.
Then place the doghouse base DHB across the trans
housing bulkheads. Glue the canopy rails in place to
the front of the doghouse base. Add DH1, 2, 3, 4 and
5. Then add the doghouse top DHT.
1
2 3
4
5 angled
6
9
10
Filler blocks
Seal and prime
1
2 3 4
DHT