deHavilland DHC-1 Chipmunk
Assembly Guide
Manzano Laser Works
The Manzano de Havilland DHC-1 Chipmunk is based on a design developed by Ivan
Pettigrew.The structural design has been updated to take advantage of laser cut parts and to
help reduce the build time.
Construction of this model can be in any order preferred, but this assembly guide has been
organized to follow a suggested build sequence. That sequence begins with the tail surfaces
followed by the wing then the fuselage. This sequence is not critical but does facilitate
construction of the fuselage. Completion of the fuselage depends on having the wing and tail
surfaces available for shaping of some of the parts.
There are three 36” x 80” plan sheets for this model as follows:
Sheet 1 - Fuselage
Sheet 2 - Wing, Stab, Fin/Rudder
Sheet 3 - Sheeting and part layouts not included on the other plan sheets
Materials used in this model include balsa, liteply,plywood, brass tubing, and piano wire. A
formed plastic canopy is also used. Most of the wood and the formed canopy is supplied with
the kit. The builder supplies 3/16” and 1/8” square balsa strip stock, piano wire, brass tubing,
and the hardware needed to complete the model.
The completed model should have a flying weight in the 5 to 6 pound range. To provide a
reasonable power level for handling wind and take offs from rough terrain, a power loading of
at least 70 watts per pound is suggested. That translates to a motor/prop/battery selection that
can deliver at least 420 watts. The battery area of the model can accommodate up to four cell
lipo packs in the size range suitable for this model.
TAIL SURFACES ASSEMBLY
1.
Begin with the stab and elevators. Assembly begins by
laminating the spars. They are made up from a lamination of 1/8"
balsa and a lamination of 1/16" plywood.
Dry fit the stab ribs to the stab spar. Make sure the tabs on the
spar tips face down.The plywood laminations faces the r bs.
Place the assembly over the plan.
With the stab assembly lined up over the plan, dry fit the leading
edges to the r bs. They will lie flat on the rib tabs. The nose of
each rib fits in the leading edge notches. When everything is
properly aligned apply glue to all joints. Also glue the 1/8" balsa
joined to the center joint of the leading edge pieces.
2. 3.
4. 5. 6.
7. 8. 9.
Remove the stab assembly from the plan. The r b and spar tabs
can be removed at this time. The 1/16" balsa center section
sheeting will be installed during the final assembly steps.
Glue the stab tips to the assembly. The leading edge, tips, and the
back side of the spar can now be sanded to shape. Refer to the
plan cross section drawings for the shape of the spar back face.
The elevators are assembled using the same procedure as the
stab. Dry fit the r bs to the spars and then place on the plan. The
plywood side of the spars face the ribs. Add the trailing edge
pieces so the rear of each rib engages the notches. When
everything is lined up glue all of the joints.
Plywood boxes made from laminations of 1/32" plywood are used
to transfer the elevator control horn inputs to the elevator halves.
Glue the parts for each horn box and then install them in the
elevator halves. The tabs fit in elevator rib E1.
Remove the r b and spar tabs. Glue the elevator tips to the
assemblies. Sand the forward edge of each elevator half to the
profile shown on the plan cross section drawing. Sand the trailing
edge to a taper following the the rib top and bottom profile. Also
sand the elevator tips.
The fin and rudder assembly is very similar to the stab and
elevator halves. Begin by making up the fin and rudder spars.
They are laminated from 1/8" balsa and 1/16" plywood.
10.
Dry fit the fin ribs to the fin spar. Place the assembly over the
plan.
Glue the fin leading edge pieces F2 and F3 together. Place the fin
leading edge on the ribs making sure the nose of each rib is fully
seated in the notches. The leading edge will rest on the tabs. When
everything is lined up, glue all the joints.
Glue the fin gusset to the assembly.
11. 12.
13. 14. 15.
16.
17. 18.
Remove the rib and spar tabs from the fin assembly. Shape the
leading edge and the rear spar face to the profile shown on the
plan cross section drawing.
Dry fit rudder r bs R9 through R12 to the rudder spar. Place over
the plan. Glue the rudder trailing edge parts R3 and R4 together.
Place the rudder trailing edge on the assembly. When every thing
is lined up glue the joints.
Dry fit rudder rib R8 to the assembly. Confirm the fit and alignment
and then apply glue to the joints. Make up rib R7 from the two
halves and the key. Sand a bevel on the forward face of the rear
half of R7 to match the plan profile. Glue the halves together using
the balsa key to align and strengthen the joint. Sand the forward
half of R7 to match the joint angle. Install R7.
Dry fit the rudder tip parts R1 and R2. When satisfied with the fit
glue the joint. Place the rudder tip on the assembly. R2 should be
centered on R3. When satisfied with the fit apply glue to the joints.
Also glue the gusset to the assembly.
The rudder horn box is made from 1/32" plywood laminations. The
core is three laminations. Build the rudder horn box and glue it to
rib R8 and the back face of the rudder spar.
Remove the r b and spar tabs. Sand the trailing edge to a taper
following the rib profiles. Shape the tip and sand the front face of
the spar to the profile shown on the plan cross section drawing.
This completes the assembly of the stab, elevator halves, fin, and
rudder. After they are covered CA hinges are use to mate the
surfaces. The balsa dorsal fin is shaped and installed on the model
during final assembly.
WING ASSEMBLY
1.
The wing assembly begins by laying a 36" strip of 1/8" square
balsa over one side of the wing plan in the location shown on the
plan. This strip generates the tip washout as the wing is built on
top.
Glue the 1/16" plywood doublers to ribs W3 and W4.
Layout one set of ribs W2 through W11 and one of the 1/8" balsa
sheet wing spars. Slide the ribs through their corresponding
openings in the spar and then twist them to be vertical. DO NOT
GLUE.
2. 3.
4. 5. 6.
7. 8. 9.
Fit the sub leading edge over the steps on the nose of each wing
rib. Make sure the sub LE is fully seated on each rib step. DO
NOT APPLY ANY GLUE YET.
Lay the UNGLUED assembly over the plan. Place r bs W2A and
W12. Slide the aileron and flap area trailing edge pieces on to the
rib steps making sure they are fully seated on each step. Again, DO
NOT glue anything yet.
Check the alignment of all the wing half parts relative to the plan.
Also make sure all of the ribs are touching the building surface and
the 1/8" square strip. A few straight pins can help make sure
everything stays in the proper place. Apply thin CA to all of the
joints.
Make up four paper tubes that are 1/2" in diameter. Allow for a bit
of overlap when rolling the tubes. Two of the tubes need to be 20"
long and the other two 7" long. Slide one of the long tubes into the
forward set of holes in the ribs. Slide a shorter tube into the other
set of wing r b holes. Apply a small amount of glue to each rib tube
interface.
Place rib W1 and parts W13 and W14. When satisfied with the fit
glue them in place. When the glue is set remove the assembly
from the building surface for the next step.
The 1/4" x 1/8" spar caps are now installed. It is recommended
that an air dry glue such as Elmer's Carpenter Glue or Titebond be
used. Apply some glue to the forward face of the spar where the
cap will go and to each rib notch. A.after the spar caps are in
place, lay the assembly on the plan over the washout strip to dry
W4
W3
Note that W7A and W7B are
together in the same spar slot
W13
W14
10.
Remove the structure from the building board. Sand the top and
bottom edges of the sub leading edge and trailing edges so they
match the contour of the ribs. Be careful not to sand the ribs.
Applying a strip of masking tape along the top and bottom of the
ribs just behind the sanding area is a good way to protect them.
Glue the trailing edge cap pieces to the wing. Make sure you use
the top piece on top.
Make up the two landing gear mounting blocks. They are made
from two laminations of 1/8" plywood with a 1/16" balsa face.
The balsa face can be sanded to match the bottom leading edge
sheeting.
Glue one of the landing gear mount blocks to the wing half. Use
the notches in r bs W2, W3, and W4. The hole goes toward the
wing root. Epoxy is recommended as the adhesive.
11. 12.
13. 14. 15.
16.
17. 18.
Cut and fit the top leading edge sheeting. Use an air dry glue l ke
Titebond for this step. Place the wing panel on the building board
over the plan when gluing the top leading edge sheeting in
place. This will help lock in the tip washout.
Remove the wing panel from the building surface. Cut and fit the
bottom leading edge sheeting. Glue it in place. Check to be sure
the tip washout has not been altered before the glue dries.
Glue the wing bolt reinforcement 1/4" balsa laminations together.
Fit and glue the filler block to the wing panel. Shape the filler
block to match the top and bottom r b contour.
Using 1/16" x 1/4" balsa strip stock, cut and glue a cap strip to the
top and bottom of wing ribs W4 through W12.
Install the 1/16" plywood servo tray rails in the flap servo rib bay
formed by W4 and W5, and the aileron servo bay formed by ribs
W8 and W9.
Install the leading edge piece. Next install the wing tip pieces.
Sand the leading edge and tip to their final shape.
Place a piece of 1/8" diameter piano wire next to
the first lamination before gluing the second
lamination. Remove the piano wire when both top
lamination pieces are in place.
Fit the bottom center section sheeting. Using the wing bolt holes
as a guide, from the top drill the bolt holes in the bottom sheeting.
19.
20.
21.
22. 23.
24.
25.
Make up each aileron and flap control horn assembly. Glue them
to the plywood rib in each aileron and flap. Also glue the balsa
pieces that provide a covering platform around the control horns to
the bottom of each assembly.
Build the ailerons and flaps over the plan. Dry fit the ribs to the
notched leading edge parts. Place the assemblies over the bottom
trailing edge pieces. Glue when aligned. Be sure to taper the rear
edge of the bottom trailing edge pieces. Note that the flap leading
edge is two pieces. Glue the forward piece to the assembly after
the other parts have been glued together.
Sand the leading edge of each aileron and flap assembly to the
profile shown on the cross sections provided on the wing sheet of
the plan set.
Also sand the wing trailing edge in the aileron area to the profile
shown by the plan wing cross sections.
Build the second wing panel following steps 1 through 18 of this assembly guide section. The two wing panels are joined using two 1/8"
plywood doublers. Use epoxy to join the wing panels. Glue the center wing dowel to one wing panel before joining both panels. With one
wing panel laying flat on the building surface, the opposite tip should be 6" above the surface.
6" at the base of W12
Fit the top center section sheeting. Sand a taper at the rear of the
rearward piece to mate with the bottom sheeting. Using the wing
bolt holes as a guide, from the bottom drill the bolt holes in the top
sheeting.
Taper
Taper
Aileron
Flap
Add pieces of 3/16 balsa to the back face of the flap leading edge and wing trailing edge where the flap hinges will be installed. Refer to
the plan for this step. Robart hinge points are used for the flap hinges. Refer to the wing plan cross section drawings to see the proper
orientation of the hinge points. Drill the flaps and wing trailing edge for the hinge points. Dry fit the flaps to the wing. Make sure they will
rotate down freely and then remove them and the hinge points from the wing.
26. 27.
This completes the wing structural assembly. The ailerons and flaps are installed after they and the wing are covered. Make sure the flaps still rotate down freely after the hinge points have been
glued. CA hinges are used for the ailerons.
After the ailerons and flaps have been installed, mount servos to the servo trays. Servo extenson leads will be necessary for the servos.
Route the servo leads through the servo lead tubes starting from the servo bays. Pull the connectors through the appropriate holes in the center section top sheeting.
Mount the servo trays using four wood screws in the corners of the trays.
28.
29.
Bend the landing gear legs using 1/8" diamater piano wire.
Place the landing gear legs into the slots of the landing gear
mounting blocks. Place a plywood retaining lug in the pockets of
the mount block. Mark the location of the retaining screws. After all
of the screw locations have been marked, dirll pilot holes for the
screws. Run screws into each hole.
Make up the four servo trays using the 1/32" plywood and 1/16"
balsa tray laminations. The flap and aileorn trays are different in
size so be sure to match the appropriate part pairs. Set the
laminations so there will be a right and left tray. The balsa
lamination faces the outside of the wing. The servo mounting lugs
are the same for all four trays.
FUSELAGE ASSEMBLY
1.
Fuselage assembly begins with the internal liteply box.
Assemble the sides, top pieces, and formers 3B, 4B, and 7B.
Dry fit all the parts before adding any glue.
Add the bottom internal box piece that fits behind 7B.
Install the top, side, forward, and rear formers. These are a
combination of balsa, plywood, and liteply parts.
2. 3.
4. 5. 6.
7. 8. 9.
Install the battery pack tray. Place one tabbed end in the notch
of 4B and then rotate the other end down so the tab fits in the
the notch in the bottom of the forward bulkhead.
Install 3/16" square balsa stringers in the slots of the formers. The
outer edges of top formers 3T,4T, 4C, 5T, and 6T are glued to the
stringers that run parallel to the top of the internal liteply box.
Install parts 4S and 7S on each side of the fuselage in the
locations shown. The bottom edge of each part is flush with the
top of the notches in the wing saddle area next to side formers 4
and 7. The parts should be on the wing saddle side of each side
former.
4S
7S
Assemble the two sets of wing saddle parts WS1 through WS3.
The wing saddles are then glued to the fuselage internal box and
the bottom of the side formers. The tabs on the wing saddles fit in
the notches of the liteply box sides. The bottom of formers 5 and 6
along with pieces 4S and 7S match the dihedral angle.
Assemble the motor mount. The mount is set up so the length can
be adjusted for the motor being used. The inner box can slide fore
and aft in the outer box. DO NOT GLUE the inner box in the outer
box until it is time to install the motor. Please note that the inner
box sets the right thrust. Make sure the top and bottom pieces
have the same orientation relative to the slanted faces.
Glue the motor mount outer box to the forward fuselage bu khead.
The tabs of the motor mount box fit in the corresponding slots in
the nose former.
WS1
WS2
WS3
10.
Assembly of the rear fuselage begins by gluing the 1/8" balsa
vertical keel parts together.
The horizontal 1/8" balsa keel pieces are glued in place after the
vertical pieces are glued together. The tabs fit in the vertical keel
slots.
Glue the rear fuselage formers to the keel parts. Use the slots in
the keel parts to locate each former segment. The rear former 13
is not installed at this time.
11. 12.
13. 14. 15.
16. 17. 18.
Bend the tail wheel leg using 3/32" piano wire. Be sure to place
the length of 1/8" brass tubing on the leg above the 90 degree
bend before bending the pushrod tiller arm. Make up the
pushrod link end from 1/8" brass tubing and solder it to the tiller
arm. Bind the brass tubing on the leg to the 1/8" plywood center
tail wheel support piece. Glue the 1/32" plywood face support
face pieces to the center support piece. Be careful not to get any
glue in the pivot tube.
Glue part KE to the bottom of the horizontal keel pieces at the rear.
Use the slot formed by the horizontal keel pieces to locate KE.
Glue the tail wheel assembly to the lower vertical keel. The brass
tube fits in the slot formed by the rear of the vertical keel and part
KE. The tail wheel leg should rotate freely without any interference
from the structure.
Bend the rudder control horn using 3/32" piano wire. Slide a 1 1/8"
length of 1/8" brass tubing on the wire after bending the push rod
link end and before bending the rudder tiller arm. Slide the 1/8"
plywood rudder horn support pieces on to the assembly as shown.
DO NOT APPLY ANY GLUE. These parts can slide freely for now.
Dry fit the rudder horn assembly and stab saddles to the rear
fuselage keel assembly. Also dry fit former 13 to help place the
stab saddles. DO NOT GLUE former 13. Adjust the vertical
position of the rudder horn brass tubing so the pushrod attachment
end is far enough below the horizontal keel pieces to clear a
clevis. When the stab saddles and rudder horn assembly are in
place glue those parts being careful not to glue former 13. Remove
former 13. Glue strips of 1/8" square balsa to the sides of the tail
wheel support assembly with the edge lined up with the bottom of
the vertical keel.
Make up and install the link between the rudder horn and tail
wheel. It is suggested that one threaded and one solder celvis be
used for the link ends.
Glue the rear fuselage structure to the forward section. The slots in
rear section former 8B fit over the tabs extending from forward
section former 8A.
8B
9
10
11
12
1/8" Brass tubing
KE
8A
8B
19.
Install the servo rails and then the servos. The servo rails are
three laminations of 1/16" plywood. They slide in to the slots
from the side. The rear slot is longer than the servo rail width to
allow for length adjustment.
Bend the elevator and rudder pushrods from 2-56 threaded
pushrod stock. Use the plan templates. Use solder clevises on
the rudder and elevator ends of the pushrods. Before making the
forward bend in the elevator pushrod slide a 16" length of
pushrod sleeve over the pushrod.
From the forward side of former 12, slide a 16" length of pushrod
sleeve under the horizontal keel piece through the hole in former
12. With the threaded clevis removed, slide the rudder pushrod
into the sleeve from the rear. Install the threaded clevis. Attach
the rudder horn clevis and then the servo clevis to their
respective control arms. The sleeve supports will be added
later.
20. 21.
22. 23. 24.
25. 26. 27.
Slide the elevator pushrod assembly into the fuselage from the
rear. It must pass to the right of the rudder control horn as
viewed from the rear. Connect the servo end clevis to the servo
output arm. The elevator pushrod assembly will get supports in
the next step. Length adjustments will be made later.
Install 3/16" square balsa stringers on the rear fuselage section
using the notches in the formers. The top stringer will need to be
tapered at the rear. The taper should start from about 5 1/2" from
the rear end of the top stringers.
The push rod supports are made from two pieces of 1/8" balsa. To
accommodate the variations in individual builds, the supports are
trimmed to fit each location. They are glued to the vertical and
horizontal keel pieces. Install a support at each fuselage former
location on both the rudder and elevator pushrods. Also glue
former 13 to the rear of the fuselage.
The bottom section of the fuselage right behind the wing saddle is
filled with a balsa block made from laminations of 1/4" balsa. That
block is installed after the fuselage sheeting has been added.
Make up the block at this time.
Also make up the laminated fuselage rear tail block. It is installed
and shaped after the fuselage 1/16" balsa sheeting has been
installed.
Elevator
Rudder
Solder
Clevis
Threaded
Clevis
Servo End
13
Taper this stringer
Install the 1/32" plywood cockpit floor pieces.
The wing bolt plate is three laminatons of 1/16" plywood. Glue the
laminations together and then glue the wing bolt plate to the
fuselage using epoxy. The tabs on the wing bolt plate fit in the
slots in the wing saddle. The bolt holes are drilled with the wing in
place on the wing saddle.
The fuselage is covered with 1/16" balsa sheet. Patterns have
been provided on the plan to help cut each sheet section to the
proper size and shape. Making up paper patterns before cutting
any balsa is a good idea to help make sure the pieces will fit the
target section properly.
After the fuselage sheeting has been installed, the filler block
behind the wing saddle is glued in place. It is shaped when the
fuselage sheeting is sanded. The edge of the filler block that
mates to the wing needs to be sanded to the wing bottom profile.
That is done by mounting the wing in the wing saddle and then
performing the final shaping of the filler block mating edge.
Balsa sheet is used under the stab to fill the area between the stab
saddle and the fuselage sheeting.
Glue the rear tail block to former 13 and shape the block.
Use cowl parts C3T and C3B for this step. Place 3CT on top of the
forward internal fuselage box just forward of former 3. Mark the
location of the notch in C3T where it strikes the top of the internal
fuselage box. Remove C3T and glue the cowl retaining lug stand
off to the fuselage box and former 3T using the mark as the
location guide. Glue the lug face to the stand off. Repeat the
process with C3B on the bottom of the fuselage box.
28.
Using the templates provided on the plan, cut the 1/16" balsa
sheeting for the cowl halves.
After the sheeting has been applied to the cowl halves, glue the
nose block laminations together. A 1/16" plywood half ring is
glued to the front face of each nose block half. Glue the nose
block halves to their respective cowl halves. The nose blocks are
then shaped and the cowl halves are final sanded.
29. 30.
31. 32. 33.
34. 35.
There are four pairs of 1/4" x 1/8" magnets that are used to
retain the cowl. Install the magnets at this time. Glue a magnet in
each of the holes in the lower cowl half keel parts. Place a
magnet on the installed units. Mark the outer face of the second
set of magnets. One at a time, remove the second magnet and
glue it in the corresponding hole of the upper cowl half. The
marked face will go toward the inside of the cowl half.
The motor can now be installed. Mount the motor to the internal motor mount box. Make sure the orientation of the motor mount box is
set so the motor will have right thrust. Slide the motor mount box into the outer box that is attached to the fuselage. Place the cowl on
the model. Slide the motor back until you have the proper clearance between the spinner and forward edge of the cowl. Carefully
remove the cowl and mark the location of the motor mount on the motor mount box. Apply some epoxy to he outer faces of the motor
mount box and slide it back onto the outer box on the fuselage to the marks. Before the epoxy sets put the cowl back on to make sure
the spinner gap is still correct.
The finished cowl is installed on the fuselage by placing the back
face of each half against fuselage former 3. Each half is then slid
vertically until the bottom edge of the rear cowl formers engage
the retaining lugs on the fuselage. The magnet pairs keep the cowl
from separating in flight. To remove the cowl simply slide each half
up and down to disengage the retaining lugs.
C3B
C3T
Mark Here
Build the cowl halves by placing the cowl keel parts over the
plan. The upper cowl half keel parts have wider notches in the
middle. Glue the formers to the keel parts. Add 3/16" balsa
stringers. For the upper cowl half, the stringers need to be two
pieces. This will eliminate bending stress that can distort the
upper cowl half.
Note: There are 2
C2T formers
Mark this face
FINAL STRUCTURAL
ASSEMBLY
1.
Before covering the model there are a few final assembly steps
to perform. They begin with the installation of the wing fillets.
Glue the 1/32" plywood fillet base pieces to the bottom face of
the wing saddles.
To help define the shape of the fillets, balsa pieces are glue to
the fuselage and fillet bases at former locations 5, 6, and 7.
The area between the fillet shape formers is filled with balsa and
light weight spackle. When the spackle is fully dry sand it to
shape using the shape formers as a guide. A piece of 1 1/2"
dowel wrapped with sandpaper is a good tool to use for the
sanding.
2. 3.
4.
5.
The rear portion of the fillets from the wing trailing edge is
created using a balsa block made from 1/4" balsa laminations.
Shape the block to fit the fuselage. It can then be glued in place.
The curved surface can be created by sanding with the same
dowel and sandpaper tool used in the previous step.
Next the stab is installed. Before performing that operation connect the elevator control horn to the elevator pushrod clevis. Slip one of the balsa stab center section sheeting pieces over the rudder
horn. Place the stab over the rudder horn on top of the center section sheet. Glue the bottom center section sheeting to the stab. The tabs on stab ribs S1 align the sheeting. Mount the wing to the
fuselage and place the assembly on a flat surface like the floor. Block the wing tips so they are both the same height off the surface. Make sure the stab is centered on the saddle and check to see
that the distances from each tip to the surface are the same. Adjust if necessary by carefully sanding the stab support pieces. Check the distance from each stab tip to the corresponding wing tip.
When both distances are the same place reference marks on the stab. Use an air dry glue and glue the stab to the fuselage. Some masking tape can be used to hold the stab while the glue dries.
Before the glue dries double check the stab alignment.
Equal
Equal
6.
7.
8.
9.
Dry fit the stab top center section sheeting piece to the stab. Slide the fin spar base through the cutout in the top and bottom stab sheeting. With the fin resting on the stab check the alignment to be sure the fin
is vertical and the fin center line is aligned with the fuselage center line. When satisfied with the alinement glue the stab top sheeting to the stab. Remove the fin from the stab. Apply some air dry glue to the fin
spar base where it contacts the top rudder horn support and stab center section sheeting. Also apply glue to the bottom face of fin rib F6. Slide the fin into position and let the glue dry.
Sand the dorsal fin to the cross section shown on the plan. Dry fit
the dorsal fin to the fuselage and fin. When the fit is satisfactory
glue the dorsal fin to the fuselage and fin.
Glue the three 1/4" balsa elevator filler laminations together. Sand
the assembly to match the elevator root rib profile. Temporarily fit
the elevators to the elevator horn. They can be retained with
masking tape. Glue the elevator filler piece to the fuselage with it
centered between the elevators. Remove the elevator halves.
10.
The landing gear leg covers are made from three laminations of
1/8" balsa. Glue the center pieces to one side of the lamination
set. Use rubber cement to glue the other side of the lamination
set to the assembly. Sand the assembly to a streamlined cross
section. Separate the rubber cement joint and rub off any rubber
cement that remains. Place the covers on the landing gear legs
and then glue the lose outer piece to the assembly. Apply glue to
the landing gear leg as well.
This completes the structural assembly. The model is covered followed by installation of the control surfaces and radio equipment.
The CG location is shown on the plan. Be sure to check the balance with the battery pack that will be used in place.
Use rubber cement
for this lamination
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