APPROACH E GI EERI G · PDF fileAPPROACH E GI EERI G ... must be taken to properly build this kit and install all radio components. ... CB, and glue to the

A H - 1 F C O B R A

E L E C T R I C

APPROACH EGIEERIG

www.ApproachEngineering.com

AH-1F COBRA—ELECTRIC PAGE # 2

APPROACH EGIEERIG AH-1F ELECTRIC MECHAICS

1.0 Purpose

To establish a process that ensures control and standardization in the manufacturing of AH-1F Cobra for use with electric

mechanics. AP102.

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-1F Cobra AP102. (A, T)

4.0 Attachments

5.0 Introduction

1. WARIG 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 (800) 435-9262

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.



6.1 Punch out the four 3/32” fuselage side pieces for each side. Assemble the side frames, (S-1, S-2, S-3, S-4) over a piece of

wax paper. 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 and have them facing

up. These will aid in the instillation of the triangle stock. Using

the notches provided assemble and glue with CA the two fuse-

lage 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. Align the fuselage doublers, FD-2, and FD-3 by match-

ing the front notch edge (A), the canopy top edge (B), and the

bottom of the wing notch (C) with the fuselage side. The

notches in the fuselage for F-3 and F-4 will line up with the

notches in the fuselage doublers. Using 30 minute epoxy glue

on the fuselage doublers. Set aside and allow to dry.

6.3 Using laser printed triangle stock reference lines, Glue ¾”

triangle stock (TRI-2) along the bottom edge of both inner sur-

faces of the fuselage side between F-4 and the tail boom end

filler. Glue ¾” triangle stock (TRI-3) along the upper edge of

the fuselage sides. Glue the 3/32” horizontal fin doublers

(HFD) to the inside surface of the fuselage sides.

6.4 Glue F-3, with the text and curved edge facing up, and F-4 into the notches of the fuselage doublers to make the fuselage

box. Using epoxy glue in the two mechanics mounts into the

notches of the fuselage doublers. Epoxy the formers and

mounts into the other side of the fuselage.

6.5 Temporarily position your mechanics 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. Logo mechanics

mount directly to the base which is assembled later. You will

want to fit the mechanics and properly place the main shaft cen-

tered in the hole in the doghouse.

6.0 FUSELAGE ASSEMBLY

A

B C

FD-2 FD-3

Match angle on

end of tri stock.

HFD

Note: Logo mechanics do not

use the rails. Check fit prior to

assembly.



6.7 Turn the fuselage over and epoxy the 1/4” light ply fuse-lage bottom to the inside of the fuselage sides. Punch out the

1/4” chin block, CB, and glue to the front of the plywood fuse-

lage bottom.

6.9 Working at the nose of the fuselage sides cut 3/4” triangle

stock (TRI-1) to match the bottom front edge to F-3 on each

fuselage side. The ends of the triangle stock should mate up

flush with F-3 and should extend past the front fuselage side

edge to be sanded off later. Cut parallel cuts to approximately

1/8” of the back surface to aid in the fuselage nose in bending

6.11 Apply water to the fuselage side nose and the triangle stock to aid in bending. Using masking tape bend the sides to

glue F-1 in place.

6.8 Turn the fuselage assembly over and glue the four 1/2” by

1.5” square hardwood landing gear blocks using epoxy. Try not

to fill the 5/16” holes with epoxy on the end of the landing gear

blocks.

6.10 Glue the ¾” triangle stock to the bottom edge of the nose

to F-3.

6.12 Glue F-2 along the canopy side matching up the upper

edge.


Landing Gear Blocks

Match upper edge

CB

PLY

BASE



6.13 Punch out the two 1/8” light ply vertical fin supports 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.

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.


Bearings 2 each

Guide Washers 2 each

Note direction of teeth

Smooth Idler

Tooth Idler

Bearings

TSR



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 Attach the 4-40 threaded shaft and link to the bell crank for the vertical portion. Attach another link to the lower bell

crank arm.

6.20 Pull out the larger diameter, longer, tail rotor tube with

the four vertical cuts in one end. Using 30 minute epoxy glue to

the vertical frame so that the bottom edge is flush with the bot-

tom surface of the bottom tail rotor tube support and the vertical

cuts are at the top of the fin assembly..

6.22 Slide the 1/8” bell crank shaft through the hole on the sides of the vertical fin support and hold in place with a drop of

CA on the outside end of the shaft.

6.24 Glue the completed assembly into the notches provided

in the fuselage side.


Bottom edges line up.

TSF

Link to tail rotor servo. The

pushrod will be connected

later.

Vertical pushrod

and link.



6.25 Make two sets of filler blocks by gluing one filler block

side, FBS and one FBM to build a right and left. Make a vertical

mark from the corner of the FBM as a sanding reference. The

face will be sanded to that mark and tapered to about 1/16” at

the tip.

6.27 Using your desired pushrod connect it to the bell crank at this time. The outer housing will be installed later. Using 1/4”

triangle stock fill the gap between the FBM and the triangle

stock on both sides.

6.29 Sand the horizontal fin to the desired shape. Note: the real aircraft has a flat top and a rounded lower surface. This

will pull the nose up in foreword flight and is recommended to

sand them to a symmetrical profile. Glue the ¼” x ¼” x 1-3/4”

balsa sticks into the notches. These will go into the fuselage

side and doublers for increased strength.

6.26 Working at the lower rear of the tail boom, trial fit the

filler blocks to ensure a good fit. When satisfied glue the filler

blocks into position.

6.28 Making two sets glue the upper and lower horizontal fins

together, from the ¼” balsa, making sure to make a right and a

left.

6.30 Using 3/32” balsa cross sheet the bottom of the fuselage

starting from behind the fuselage floor to the end of the tail

boom.


HF-B

HF-B

HF-T

Sanding Mark

Control Rod

Connector

1/4” Tri Stock



6.31 Using 3/32” balsa cross sheet the upper and lower sur-faces of the nose.

6.33 Remove the center section of the vertical fin base to al-

low free movement of the belt drive. Also test fit the horizontal

fins for a proper fit. Do not Glue the ¼” x ¼” x 1-3/4” balsa

sticks into the notches. These will go into the fuselage side and

doublers for increased strength.

6.35 Punch out the 1/4” balsa tail rotor pushrod supports, DDS-1 and DDS-2, and glue them on the bottom sheeting sur-

face. Make sure that they are properly aligned and provide a

straight support for the pushrod. When satisfied glue the push-

rod outer tube to the supports with thick CA.

6.32 Punch out the 1/8” ply canopy backing plate, CBT, and transmission backing teeth, TBT. Matching up the profiles glue

them to the back of the fuselage doublers. This is to hold the

canopy and transmission guide teeth flush for a good fit.

6.34 Slide the front pushrod tube support (DSS-3) up so that it is supporting the tube. The support should line up with the tri-

angle stock, sides, and balsa cross sheeting floor. Put the push-

rod tube through the hole that fits your desired servo layout.

When satisfied with the fit glue in place with CA+. Depending

on your radio arrangement you may want to install a receiver

antenna wire tube now for ease of instillation.

6.36 Glue in the 3/8 triangle stock along the balsa floor as shown. This will aid in sanding a rounded corner. Apply trian-

gle stock to both sides.


DDS-1

DDS-2

1 1/2” long

6 1/4 Long

5 3/8” Long



7.1 Sand the face of the fuselage assembly flush with F-1.

Glue on the two 1/4” balsa 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.

7.3 Sand rounded corners on the three outside edges of the TSU back plate.

7.5 Glue the TSU bottom pieces into the notch in the TSU

back plate.

7.2 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.

7.4 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.

7.6 Glue the four nose blocks together starting from NB-1 on

the bottom to NB-4 and glue the assembly to the top of the TSU

back plate against F-1.

7.0 OSE AD TSU (TELESCOPIG

SIGHT UIT) ASSEMBLY



7.7 Sand the nose blocks flush with the top of the cross sheet-ing on the fuselage nose. Sand a small radius on the front of the

nose block.

7.9 Cut out the TSU sanding templates from the sticker paper

and stick to the front of the sight units. Sand back about 1/4”

around the sanding template.

7.8 Punch out six 1/4” balsa telescoping sight units. Make two

sets of sight units by gluing 3 T-2’s together for each side.

7.10 Glue one T-1 between the two TSU assemblies and one

T-3 on each side of the assembly. Sand the glued assembly to

the desired finished shape.

7.0 OSE AD TSU (TELESCOPIG

SIGHT UIT) ASSEMBLY

otes:

T-1

T-2



8.1 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. The inside surface will

be flush with the canopy side lower surface (detail A). Ensure

that there is a 1/8” gap on the front and back of the guide teeth

to the canopy sides (detail B). The bend in the canopy teeth

(detail C) must line up with the bend in the canopy side. Glue

with CA.

8.3 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.

8.5 Cut out the three canopy top sheeting CT-1, CT-2, and CT-3. Start by gluing CT-1 to the top edge so that the end with the

arrows lines up with the bend in the canopy. Sand the edge of

the canopy top sheeting so that it is flush with the next section.

8.2 Using the printed reference lines as a template, 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. The Triangle

stock will extend past the upper edge and will be sanded off

later. Using CA glue along the upper edge allowing for the

formers.

8.4 Using masking tape pull the canopy sides to conform with

the curve of C-1, C-2 and C-3 and glue with CA. Glue in C-4 in

the corner of the front glass so that the inside lower edge is

flush with the bottom of the triangle stock. Sand the top of the

triangle stock flush with the canopy sides for cross sheeting.

8.6 Repeat the same steps for CT-2 and CT-3. Sand the edges

flush with the previous section. Glue the WSPS on top surface

of the canopy and secure underneath with 1/4” tri stock. Cut

out the canopy glass and trial fit into place. Sand as necessary

8.0 CAOPY ASSEMBLY

B

A

B

C-4

WSPS



9.1 Punch out the 3/32” transmission sides and the 1/8” light ply transmission guide teeth (TGT). Making sure to build a left and a right side, position the guide teeth so that the inside line of the guide teeth line up with the bottom of the transmission sides (detail A). The back edge tab (detail B) will extend past the back edge of the transmission side. The front edge (detail C) will be lined up with the transmission front edge. Using CA, glue the guide teeth along the bottom edge of

the transmission sides.

9.3 From the 1/8” plywood sheet cut out E-1and glue 1” of the

lower surface of E-1 to the transmission sides. Glue the ¼”

transmission sub base to the upper rear of the transmission

9.5 Punch out the ¼” transmission mid blocks and glue to-

gether making sure to have both ends labeled back together.

Using CA, glue the transmission mid blocks together.

9.2 Glue the 2” long by 3/4” triangle stock to the upper edge of the transmission sides just in front of the intake openings.

9.4 Turn the transmission assembly over and glue Trans base,

TR-B, on the inside lower surface of TR-SM so that the back

edge is flush. Then apply 1” x 1” long triangle stock to the edge

of the fuselage sides and the transmission sub base.

9.6 The transmission sub block will be aligned with the back

edge of the transmission sub base. The transmission sides must

be pulled out to match the edge of the transmission mid block

assembly. Glue to the upper surface of the transmission assem-

bly. Glue the remainder of the 3/32” balsa transmission sides

up E-1. Cross sheet with 3/32” balsa the remainder of the upper

surface from the transmission mid blocks up to E-1.

9.0 EGIE AD TRASMISSIO

BAY ASSEMBLY

A C

B

TR-B

3/4” x 2” Triangle

E-1

TR-SM 1” Triangle stock x 1”

T-MID

T-MID



9.7 Position the 1/4” balsa trans top pieces, T-TOP, together so that the part labeling is close together in the center. Glue over

the top of the transmission mid blocks making sure to have the

labeled back side to the rear of the assembly. Sand the sides

and rear of the transmission assembly flush with the sides.

9.9 For ease of sanding the intakes must be shaped prior to

gluing to the transmission assembly. Using intake template 1,

from the provided sticker paper, shape the front of the intakes.

Apply the adhesive template to both sides of the intake and sand

the intake to the template shape.

9.11 Using intake template 2 apply to the rear end of the en-

gine cowling side. There should be a 1/8” edge left on the rear

of the cowling side. Sand the cowling side to match the pro-

files.

9.8 Making sure to build a left and a right engine intake posi-

tion the ¼” intake sub mounts (ESB) on the ¼” intake sides.

Glue with CA.

9.10 Sand the center portion of the intake to a rounded shape. Only sand the edge between the intake sub mounts.

9.12 Apply the intake template 3 over the supplemental air

intake on the cowling sides. This is a template to aid in sand-

ing the intake angle. Sand a flat surface to the inside edge.


BAY ASSEMBLY

T-TOP T-TO

P

BACK

BAC

K

AFTER SANDING

BEFORE

SANDING

BEFORE SANDING

AFTER SANDING AFTER SANDING



9.13 Flip the assembly over and apply the same angled surface

on the inside back edge of the supplemental intake.

9.15 Place E-2 on the back of the transmission assembly and

mark the profile that it will create on the back surface. Mark the

line 3/32” outside E-2 to account for the cross sheeting that will

be applied later.

9.17 Glue the cowling sides to the transmission assembly.

9.14 Sand a rounded profile along the lower edge only of the cowlings.

9.16 Place the cowling intake assemblies over the transmis-

sion assembly and mark the location where the cowling sides

will be placed. Take note not to sand to the profile of the intake

assemblies all the way across the back of the transmission. The

center of the transmission should not be sanded past the profile

sketched on the back of the transmission from the 3/32” offset

from E-2 that will be created by the cross sheeting. Sand the

transmission upper blocks to match the sketched profiles.

9.18 Use the provided transmission sticker templates, intake

template 4, as a guide to sketch the approximate lines to sand to.


BAY ASSEMBLY

INSIDE SURFACE SANDING

LEAVE

SQUARE

ROUNDED

ROUNDED



9.19 Sand the upper surfaces of the transmission assembly to

the desired rounded finished shape. Sand a rounded profile and

have a smooth transition to the top of the transmission taking

care not to sand off the lines made in step 9.15.

9.21 Keeping the transmission assembly on the fuselage as-

sembly, sheet between E-2 and E-3 with 3/32” balsa starting at

the center. Note: wetting the balsa will aid in bending around

the curved surface.

9.23 Place the trimmed doghouse on the transmission assem-

bly and trace the outside contour onto the transmission.

9.20 Place the transmission assembly on the fuselage assem-

bly to ensure a proper fit. Cut out the 1/8” ply E-2, E-3, and

two engine exhaust supports, EES. Glue E-2 on the back of the

transmission assembly. Glue EES into E-2 noting that the

notches are keyed for proper orientation. Using a scrap piece of

3/32” balsa cross sheeting place under E-3 as you glue it to the

EES.

9.22 Cut out the bottom edge of the vacuum formed doghouse

to match the profile of the upper surface of the transmission

assembly.

9.24 Carefully cut out the two transmission guide edges, DH-

1, from the 3/32” balsa sheet. Using CA+ glue just inside the

line marked on the previous step.


BAY ASSEMBLY

E-2

E-3

EES



9.25 Using a knife, razor, or Dremel cut out the material be-

tween the doghouse edge pieces. Trim away any excess balsa

inside the transmission assembly.

9.27 Sand the doghouse top to the finished rounded shape and glue in place.

9.30 Glue the exhaust support (ES-1), from ¼” balsa, centered

on the back of the transmission.

9.26 Glue the doghouse on the top of the transmission assem-

bly using CA+. Punch out the 1/4” balsa doghouse top and po-

sition it over the doghouse. Draw the inner circle location onto

the vacuum formed doghouse and cut out.

9.28 Using a Dremel clear out excess balsa on the inside sur-

face of the transmission bay.


BAY ASSEMBLY

ES-1



10.1 Punch out the 1/8” light ply wing spars and the 3/32” wing ribs W-1, W-2, and W-3. Referring to the Appendix, glue

the ribs to the wing spar. Glue on the ½” triangle stock by 3

3/4” centered on each wing spar leaving at least 3/32” on the

upper and lower surfaces for sheeting.

10.3 Apply CA to the lower surface wing ribs and wing spar. Bend the cross sheeting over to match the contour of the wing

ribs. Note: wetting the wood will aid in bending. Sand the

cross sheeting trailing edge to match the wing rib contours.

10.5 Apply CA to the wing ribs and wing spar. Bend the cross sheeting over to match the contour of the wing ribs. Note: wet-

ting the wood will aid in bending. Sand the cross sheeting trail-

ing edge to match the lower wing surface. Sand the leading

edge to match the upper and lower wing sheeting and round to

desired shape.

10.2 Using the laser cut 3/32” lower wing sheeting, sand a small angle to the leading edge to match the angle of the leading

edge. Apply CA to the front of the sheeting and glue to the

leading edge.

10.4 Using the laser cut 3/32” upper wing sheeting, sand a small angle to the leading edge to match the angle of the leading

edge. Apply CA to the front of the sheeting and glue to the

leading edge.

10.6 Depending on your desired finishing technique the wing can be epoxied to the fuselage later to aid in finishing and sand-

ing. Glue 1/4” triangle stock to the inside of the wing root

against the transmission teeth backing.

10.0 WIG ASSEMBLY

Trailing edge sanding.



11.1 Take out the two rocket launcher tubes. Carefully cut out the four 1/8” light ply rocket launcher faces. Position the rocket

launcher faces so that the holes line up from front to back. Glue

flush with the back and front surfaces of the tubes.

11.3 Sand the rocket launcher pylons to the desired finished shape.

11.5 Making sure that the rocket tubes are properly aligned,

glue the rocket tubes to the rocket pylons.

11.2 Punch out the 1/8” lite ply rocket launcher stabilizers (RLS) and the ¼” balsa rocket pylons. Make two sets of two

rocket launcher pylons.

11.4 Punch out the 1/8” light ply rocket stabilizers and glue in the provided slots. You may glue the rocket launcher tubes to

the stabilizers at this time depending on your finishing tech-

nique. It is recommended that you finish the pylons and tubes

prior to gluing.

otes:

11.0 ROCKET LAUCHER ASSEMBLY



12.1 Punch out four ¼” balsa wing tips (TLS), and two ¼”

balsa wing tips centers (TLC). Glue one balsa wing tip center

on each side of the wing tip center. Make two launchers total at

the same time.

12.3 Slide the 1/8” tow supports into the slots of the wing tip assembly. Glue in place with epoxy to allow you time to prop-

erly position the supports.

12.5 Pull out the four TOW tubes and slide in place on the

rails. Depending on your covering technique you may want to

permanently fasten the TOW tubes on at a later time to aid in

finishing. When satisfied glue in place with CA.

12.2 Sand the wing tip assembly to the desired finished shape.

12.4 Glue the 1/8” tow holders on the notches on the front of the TOW assembly.

OTES:

12.0 TOW LAUCHER ASSEMBLY



13.1 The 20mm gun can be made to rotate with the use of a

servo. Parts are included for this option. Punch out the 1/8” lite

ply gun base, gun side supports, and gun supports. Glue the gun

supports into the notches of the gun base.

13.3 Prepare the three 5/16”diameter wood dowels by drilling

a 1/16” hole in the end. The barrels then need to be tapered.

One easy method is by putting the back end in a drill bit and

spinning it while a helper sands it.

13.5 Glue the three barrels into the gun base so that the dowels are flush with the ends. Punch out the front and middle barrel

support from the 1/8” ply and slide into place. Use a small

amount of CA to glue in place. Paint and finish the gun turret to

finished appearance.

13.2 Using left over 1/16” balsa, cross sheet the gun supports. Run the grain perpendicular to the gun side supports. Use a

small amount of water to wet the balsa to aid in bending.

13.4 Glue in the gun side supports in the notches in the gun base. Slide in the ¼”diameter balsa sticks into the hole of the

gun side supports and sand flush.

13.6 Punch out two 1/4” balsa gun chin blocks and glue to-gether..

13.0 20mm CAO ASSEMBLY



13.7 Feather one end of the chin blocks down to about 1/8” on the one end..

13.9 Punch out the gun mount support block, GSB. Align the

hole with the hole created from the balsa gun chin blocks and

glue to the bottom inside surface of the nose cross sheeting.

13.11 This step should be completed after finishing and paint-

ing the fuselage and gun. Slide the gun assembly up through the

hole. Slide the spring over the wood dowel. Using CA+ glue

the 1/8” ply gun control horn (GCH) over the dowel.

13.8 Position the gun chin blocks to the lower nose cross sheeting and mark the position. Glue the feathered down balsa

gun chin blocks to the bottom surface. Using a 1/4” drill bit, cut

out the bottom sheeting through the provided hole in the gun

chin blocks.

13.9 Glue the 1/4” by 1.5” wood dowel into the top of the gun assembly. The dowel should be inserted all the way to the top

of the barrels.

13.0 20mm CAO ASSEMBLY

OTES:



14.1 Trial fit the transmission assembly on the fuselage. You

will note that the tabs on E-2 extend down the side of the fuse-

lage sides to keep the surfaces matched. Cross sheet the upper

surface of the tail boom using 3/32” balsa starting from the

notches by the transmission to the end of the tail. Note: The

cross sheeting goes underneath the trailing edge former, TE-1.

14.3 Cut the ¾” balsa triangle stock leading edge to match the

upper tail boom cross sheeting and the top leading edge support.

Glue the leading edge to the cross sheeting and the leading edge

supports.

14.5 Wet down the vertical fin sheeting to aid in bending and

let it soak in for a minute. Apply CA+ to the tail boom supports

and trailing edge formers and bend the sheeting into place. The

sheeting will overhang past the end of the trailing edge formers.

Once the glue has dried sand the sheeting to match the other

sides profile. Repeat step 14.4 and 14.5 for the other vertical fin

side. Sand the upper edge flush with the leading and trailing

edge supports.

14.2 Glue the 1/8” light ply vertical fin trailing edge former

TE-1 into the slots provided.

14.4 Using 1/16” balsa laser cut vertical fin sheeting (VFS), sand the leading edge to match the triangle stock for a better fit

and glue bond.

14.6 Sand the ¾” balsa triangle stock leading edge to the de-sired final shape.

14.0 FIAL ASSEMBLY

TE-1



14.7 Mark lines ¾” from the tail boom corners on the sides,

top, and bottom to aid in sanding. You will want to sand a

rounded edge and feather it up to the line. Leave the corners

that sit under the transmission assembly square.

14.9 Using a ½” square balsa stick, round the top corners and run from the vertical fin leading edge to the transmission back

for the tail rotor drive shaft cover. A tip to aid in sanding the

drive shaft cover to the right shape is to wrap sandpaper around

the leading edge for a form and sand the cover to shape.

14.11 Cut ¼” balsa triangle stock to fit along the sides, CB-3,

along the lower inside surface. After gluing turn the assembly

over and sand the lower surface flush with each other.

14.8 Using various grits of sandpaper round the tail boom and

lower fuselage corners to a rounded shape. The tail boom end

under the vertical fin should be sanded down to match the pro-

file of the vertical fin.

14.10 Build the lower chin block by starting with punching out the chin block front (CB-1), rear (CB-2) and side (CB-3)

pieces. Glue together to form the box structure. Make sure that

the single notch in CB-1 and the two notches in CB-2 are down.

14.12 Cross sheet the lower surface with 3/32” balsa.

14.0 FIAL ASSEMBLY

Leave square corners

CB-1

CB-2

CB-3

1/4” T

RI ST

OCK



14.13 Sand the corners of the chin block to their final rounded

14.15 Turn the assembly over and strengthen the WSPS by

adding the 1/4” by 5/8” triangle stock.

14.17 Punch out and glue the two ¼” balsa AC lights together.

Sand to the desired finished shape. The light goes on top of the

doghouse behind the main mast.

14.14 Cut out the sheeting in the center notch of CB-4 to al-low the Wire Strike Protection System (WSPS) to extend

through.

14.16 Depending on your aircraft setup you can make this

hatch removable for charge ports, batteries, switches, ect. Oth-

erwise you can glue on the chin block and have the canopy re-

movable. Magnets are included to make the hatch removable

and is covered later in detail.

otes:

14.0 FIAL ASSEMBLY



15.1 Punch out the two 1/8” ply vertical fin leading edges, TSF, and glue to the 1/16” balsa vertical fin side leading sheet-

ing, VFS-L, by aligning the back edge of the sheeting and the

formers with the formers separated by 1.25”. Only glue the

back edges for now and the sheeting will be formed to shape

later.

15.3 Apply glue to the remaining edge of the lower formers

and glue the sheeting along the profile. Using a flat sanding

surface sand the back and front edges parallel.

15.5 Glue the 1/8” ply vertical fin mounts, VMT, to the inside

edge of balsa sheeting. Temporarily place the assembly on the

aircraft for a guide to sand the leading edge to match the lower

part of the fin. Sand the leading edge to the desired shape.

15.2 Punch out the upper leading edge former, LE-T, from

1/8” plywood and glue on the upper edge of the sheeting and

matching up the rear edge.

15.4 Using a piece of ¾” balsa x 3.5” triangle stock and glue

to the leading edge of the assembly so that the triangle stock

overhangs the sides equally.

15.6 Punch out the ¼” balsa vertical fin top, VFT, and glue

centered on the top of the leading edge assembly.

15.0 VERTICAL FI COVERS

1.25”



15.7 Punch out the two 1/16” balsa vertical fin trailing edge sheeting, VFS-R, and the trailing edge formers TE-3 and TE-4

from 1/8” ply. Start by gluing only the front edge of the form-

ers parallel with the bottom and top edge and flush with the

leading edge on one side of the sheeting.

15.9 Punch out the two vertical fin sheeting tongues, TVF, and glue 3/8” down from the bottom edge of TE-4.

15.8 For best results wet the side sheeting to allow it to bend over the contour. Glue the sheeting one side at a time along the

formers and glue the trailing edge together. Sand the trailing

edge to the finished shape.

15.10 Assemble the two vertical fin covers and check for

proper fit. Sand the top balsa block flush with the sides and to a

rounded shape. Trial fit over your tail rotor and cut away the

necessary sheeting for proper clearance.

15.0 VERTICAL FI COVERS

3/8”



16.1 Finish sand your entire model using fine grit sandpaper to

prepare it for finishing. There are many ways you can finish

your aircraft with each having their advantages and disadvan-

tages:

• Iron on film covering: Simple to use, lightweight, no

messy agents, large variety of colors, and low finishing

time. However it gives a more shiny appearance and may

bubble over time.

• Fiberglass and Urethane: Lightweight finishing tech-

nique, adds strength to the fuselage, and with all the paint

colors available you can give it a highly realistic finish.

This technique takes added time in allowing it to set and

covering time.

• Fiberglass and Epoxy: Adds strength to the fuselage, and

with all the paint colors available you can give it a highly

realistic finish. This technique takes added time in allow-ing it to set, increased weight, and covering time.

16.3 Epoxy the rocket launchers and TOW launchers to the

wing.

16.5 Epoxy the horizontal fins to the notches in the aft tail boom.

16.2 Note: Depending on your finishing technique the order of gluing on the sub assemblies will vary. Finish sand your

entire model. Finish your model and sub assemblies with de-

sired paint scheme.

16.4 Using epoxy glue on your wings into the provided notches in the fuselage. Using 1/4” x 3/4” long triangle stock

glue to the inside wing root for strength.

16.6 Cut out the canopy glass by trimming the plastic about

3/32” from the corner. Insert the glass from the inside of the

canopy assembly. Check the fit of the glass making sure it is

flush on the outside surface and glue the canopy glass into the

canopy assembly.

16.0 FIAL FIISHIG AD ASSEMBLY

Tri Stock



16.8 Trim out the vacuum formed engine exhaust and gun

cover. Paint the exhaust assembly flat black. Glue the exhaust

on ES-1, installed earlier on the transmission bay cover assem-

bly, when finished with painting.

16.9 Apply 30 minuite epoxy into the landing gear holes and

slide the landing gear assemblies into the fuselage holes. Place

some weight in the fuselage and allow the gear to set.

16.8 Assemble the landing gear by first applying a small

amount of epoxy in the landing gear boots. The shorter section

of the boot arc goes on the inside. Before the glue sets assemble

two gears on the skid and ensure proper alignment. Make two

sets and move to the next step before the glue sets.

16.10 Using 1/2” triangle stock strengthen the landing gear blocks by gluing the triangle stock on each side of the block to

the floor.

16.12 Remove your canopy, tail boom, belt drive, landing

gear, and rotor head. Note: Pictures in this assembly sequence

shows the fuselage in unfinished form for clarity of the pictures.

16.0 FIAL FIISHIG AD ASSEMBLY

1/2” T

riangle Sto

ck

1” Trian

gle Stock

Longer straight section

Shorter straight section

16.11 Epoxy 1” triangle stock by 1/2” wide to the top of the landing gear blocks up against the fuselage doublers.

ES-1 fits in this end



17.1 Install the short tail boom piece into the tail boom mount

that holds the belt drive gear. Install the two servo mounts, if

you are installing your servo here, and move to the next step.

17.3 Making sure not to have a twist in the belt drive, install

the tail rotor drive belt to the boom mount. Check to make sure

that you have the proper belt direction for tail rotor rotation.

The top belt should be on the left side of the gear when viewed

from the back.

17.5 Install the main mechanics to the rails using removable

loctite to secure the screws. At this time reinstall the tail boom

belt drive mechanics to the mechanics and check for proper gear

mesh.

17.2 Plan your receiver, speed controller, and other compo-

nents where they will be placed in the fuselage. Make any nec-

essary attachment points for the components.

17.4 Temporarily set your mechanics and battery into the fu-

selage and determine your proper CG. The battery can be

moved around to achieve balance. When satisfied construct a

battery compartment to secure the battery. Plan battery removal

during this step. This arrangement can easily be pulled fore-

word and down through the hole in the bottom of the fuselage.

17.6 Install the tail rotor gearbox by first sliding the locking ring over the tail boom and the short tail boom inside the verti-

cal fin. Install the gearbox and screws to secure it to the tele-

scoping tube. Pull the gearbox and tube out to achieve proper

belt tension and screw down the set screws, with removable

loctite, to lock the tube into place making sure the gearbox is at

a proper 90 degrees to the vertical fin.

17.0 ISTALLIG THE MECHAICS

Telescoping Tube

Locking Ring



17.7 Connect your tail rotor control rod by first connecting it to the gearbox. Important: Start by feeling the total travel of

the control rod and set the center of the travel in the flat pitch of

the tail rotor blades. Failure to center the bell crank could al-

low it to come in contact with the belt! When satisfied attach

the control rod to the servo.

17.9 Using the provided magnets place two each into the chin

block. Cut the balsa away so that the magnets will lay flush

with the top surface.

17.11 Complete a functional check to make sure that your

servos and gyro are going the correct way when commanded.

Depending on the mechanics your gyro reversing may need to

be used. Complete all necessary range and safety checks,

charged batteries, final inspection and enjoy your flight.

17.8 Install the transmission and canopy assembly and fasten

with four small screws each through the fuselage and into the

guide teeth. Re-install your rotor head and check for proper fit

and that there is no binding.

17.10 Mark the appropriate position in the fuselage bottom to

put the mating magnets into place. Recess the balsa to allow the

magnets to sit flush with the bottom surface. Before you glue in

place make sure that you have the polarity of the magnets cor-

rect.

Thank you for your interest in Approach Engi-

neering aircraft. We are committed to provide

any necessary help to make your project a success.

We would love to see pictures of your completed

aircraft and add it to our data base on the website

for others to enjoy.

17.0 ISTALLIG THE MECHAICS

Approximate screw

locations

Magnet

Magnet

Magnets



18.0 APPEDIX

CAOPY EXPLODED VIEW

TRASMISSIO EXPLODED VIEW



18.0 APPEDIX

TOW LAUCHER EXPLODED VIEW

ROCKET LAUCHER EXPLODED VIEW



18.0 APPEDIX

VERTICAL FI EXPLODED VIEW

T-2 SECTIO VIEW



18.0 APPEDIX

SID

E PROFIL

E VIE

W

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TOP VIE

W