The construction of my new Carden 40% Extra 330 is going
to wait for awhile because next up is the Carden 37% YAK with this full
construction article. The building board has been cleared - the CUDA
is in the trailer ready for frequent trips to the flying field. It is
time for a new 40% (OK 37%) to add to the hangar. The wood and drawings
should be on the way to me in the little brown truck by mid May. That's
what brown can do for me!
Keep an eye out for updates to the project they should be starting soon.
I am also in the process of putting together a hardware kit of items
similar to the 40% hardware kit on this web page with specifics for the
YAK.
As always questions and comments are always welcome..................
For a complete list of parts used and available through Aero Protect,
please visit: Hardware Kits
Section > YAK-54
The wings and tail feathers follow a Carden standard of solid foam
core with balsa sheeting.
Working with the sheeting and the wing foam wing cores is where you
can start seeing the attention to detail and quality of product Carden
Aircraft puts into their designs and kit.
For ailerons the hinge line is 48 inches giving three equally spaced segments
16 inches apart. I will be using 2.5 inch Pro-Links with RCL70’s 8-32
Swivel Offset Clevis on the control surface and AirWild 1.25 inch servo arms
with RCL87L (Left thread ball links). With this setup I measure 0.63 inch
back from the hinge line and 3.38 inches up from the center line for the
servo output shaft centerline. Total distance from aileron 8-32 screw mounting
center to the servo output shaft center is 4 inches. Even though the servo
arm will be 1.25 inches I offset the servo only 1 inch which greatly reduces
the amount of angular offset that occurs when the servo arm rotates through
its full motion. Just a recommendation.
Wing01 I prefer gluing
the sheeting together first because it allows me to pre-sand both sides
on a flat surface with a palm sander and long sanding bar. Start taping
the sheeting together. Now that is what I am talking about – Quality – take
a few minutes and look at how nice the sheeting has been true edged
for you.
Wing02 After the sheeting
has been taped together turn it over, open the seam over a corner and
apply the glue. I use Elmer’s interior/exterior wood glue. Tape
the seam closed and finish gluing the panel.
Wing03 Those old encyclopedias
still have a good use. I cover the sheeting with wax paper and then
lay on the books over night while the glue cures.
Wing04 One wing panel
finished with the tape removed ready for sanding.
Wing05 My first step
with the wing core is to cut the servo bays, servo support notches,
and servo wire exit slot. I have made templates from lite ply and hot
wire cutting tools from 12 gauge copper wire. I place wheel collars
on the wires and use them to set the depth of cut. Using a soldering
iron with the copper wires I first cut the servo supports slots then
the servo bays. I then use a long straight edge and cut the servo wire
exit slot. Accurate measurements are critical to make the servo bay
cut outs after sheeting. (Carden Step 4)
Wing06 Hot wire cutting
complete.
Wing07 Servo mounts
epoxied in place. (View Elev8 for an explanation
of the way the mounts are installed)
Wing08 Servo wire
exit slots.
Wing09 Wing phenolic
tube with balsa end cap in place and trial fit of the socket support
plate.
Wing10 Wing tube socket
support scribed to sand to shape. (Carden Step
2)
Wing11 From this point
forward, Elmers Ultimate Glue and Pro Bond are interchangable (they
are the same glue but Elmer's has just renamed Pro Bond Polyurethane
to Ultimate) and it will be used to glue the phenolic tube into the
cores. With a ¼ inch drill make a few small funnels in the top
of the wing core along the hot wire groove. This makes it easier to
get the Pro Bond down in the tube slot. (Carden
Step 3)
Wing12 Place the phenolic
tube into its slot up to the first funnel and squeeze Pro Bond down
the funnel. Slide the phenolic in and out twisting it and working your
way down the slot. Make sure the tube is well coated and finally fill
the hot wire slot. Tape over the slot and tape the tube socket in place.
Place the wings in their cradles and weight them down for the glue
to cure.
Wing13 This shows
how the Pro Bond actually foams up and fills in the wing tube hot wire
groove.
Wing14 Close view
showing the wing tube socket sanded flush with the core.
Wing15 I prefer gluing
the sheeting together first because it allows me to pre-sand both sides
on a flat surface with a palm sander and long sanding bar. After the
panels were all dry and the tape removed I sanded each surface with
an electric palm sander down to 220 grit. It is definitely worth the
time at this step to sand everything smooth because after assembly
onto the wing cores all that is left is final sanding. I also prefer
sanding a flat surface than a curved surface.
Wing16 Sanding wing
cores prior to sheeting. (Carden Step 5)
Wing17 Bottom of the
wing panel ready for sheeting. Notice the servo bay support slots have
been filled in with scarp foam pieces.
I use Elmer’s Pro Bond Polyurethane glue to bond the foam cores
to the balsa sheeting. The key here is to make sure you do this on
a very flat surface so you don’t build in any warps to the surfaces
and pile on the weight to force the glue into the foam core of the
wing. I use 300 pounds of weight on each wing panel. After the glue
has cured (over night) the weight is removed and the leading and all
edges are sanded flush with the foam cores and trued. The leading and
trailing edges are glued and held in place with masking tape.
Wing18 Wing panel
after sheeting and trimming. (Carden Step 6)
Wing19 Wing panels
with leading and trailing edges being glued and held in place with
masking tape. (These are 330 wings but the YAK wings are the same concept). (Carden
Step 7)
Wing20 Using a micro
plane remove the majority of the excess leading and trailing edge balsa.
Wing21 When the plane
brings the excess balsa down close to the surface lay on 3 to 4 layers
of masking tape to protect the surface from gauges while sanding the
rough shape. Remove the masking tape and use the sanding bar to bring
the leading and trailing edges down to the wing skin surface.
Wing22 The wing with
the servo bays cut-out. This is where carefully measuring really pays
off.
Wing23 Closer view
of the servo bay cut out.
Wing24 The wing root
is glued cut to size and glued in place using aliphatic glue. Notice
the servo wire exit hole has also been cut out prior to installation.
Tape the root in place and set aside. (Carden
Step 21)
Wing25 The wing root
sanded to shape and the wing tube sanded flush to the root.
Wing26 Time to mount
the wing anti-rotation hard points into the wing root. (Carden
Step 22D)
Wing27 10-32 blind
nut installed to the back of the plywood block and the wing root carefully
cut out. (8-32 is all that is required and is
what is called for in the Carden instructions) Take the time
to only cut as deep as you need.
Wing28 Wing anti-rotation
mounting plates installed. For proper installation thread the 10-32
bolts in place and through the blind nut. Coat the exposed bolt with
Vasoline so it will not stick. Using 30 minute epoxy glue in the anti-rotation
mounting plates.
Wing29 The aileron has been cut free, leading and trailing edges installed
and sanded to shape along with the 1/16 inch balsa end caps.
Wing30 Refer to Elev29 through 31 for hinge point installation and
beveling
Wing31 The wing tip has been glued in place and taped to dry. I use
aliphatic glue for gluing the balsa blocks on. Notice the aileron is
in place, slightly pulled back from the hinge line, and glued in place.
This is done to allow uniform shaping of the wing tip and aileron tip.
The aileron is pulled back a little from the hinge line to allow a
little area to be able to cut it free after shaping.
Wing32 For shaping the tip most of the material is removed using a
razor plain to get it close to the wing shape.
Wing33 After it is close to the shape of the wing surface tape is applied
to protect and prevent gouging of the wing sheeting while the tip is
then rough sanded to size.
Wing34 The tape has been removed and final sanding to the shape completed.
The wings still need several sanding steps before being ready for covering.
Wing35 To uniformly round over the tip I have found it easiest to mark
the tip center line and tape off the half not being worked on. Again
this prevents gouging and excess sanding helping to keep the shape
of the tip.
Wing36 Wing tip complete.
Wing37 Another view
of the wing tip ready to have the aileron separated.
Wing38 A hobby saw
blade is used to cut through the connection point.
Wing39 The aileron
has been separated and sanded to shape.
Wing40 Aileron hard
point locations being marked.
Wing41 The hard point
block location has been penciled in and ready to be cut out.
Wing42 To cut the hard point locations
out I mark the depth of the wood block (3/8”) on the knife blade
so the cut is not made to deep.
Wing43 The wood block
hard point location has been opened up on the ailerons and is ready
for final shaping and installation.
Wing44 The hard point
block with control surface screw is placed in the cut out and the aileron
bevel is marked for sanding to shape. Refer
to Elev 37 and 38 for hard point installation information.
Wing45 Servos installed
to check for proper fit and work out servo extension lead lengths
Fuse01 The first step
for me building the fuselage is cutting the lightening holes in the
motor box. To help, Carden has marked the
location of the lightening holes by pre-drilling the center points – just
another of the many personal touches you will find and is a trademark
of a Carden. The lightening holes are optional and not a requirement. I
have chosen to only cut the top row out because the plane will be carrying
the MTW canisters and will be housed in the lower section of the motor
box. The circle cutter being used on the drill press is a Sears Craftsman
Circle Cutter Catalog Number 25293. The cutter works great because
it cuts a very clean circle in the plywood. When cutting the holes
make sure you clamp the parts so they don’t move while cutting.
There are some good size holes so take it slow and easy. Keep all ten
fingers you will need them to fly. (CARDEN Step
13)
Fuse02 Lightening
holes have been cut.
Fuse03 Building the
truss sides on the board. I place a long straight edge along the top
to make sure the surface is straight. The top surface of the truss
assembly will be placed on the plans when the fuse is framed up so
keeping everything square is critical.
Fuse04 Take a little
time before starting the truss assembly and sort through the 3/8 inch
square stock. Pick out (9) nine of the stiffest, strongest pieces for
the longeron pieces to produce the strongest assembly possible. Take
the care and make the angle cut/seams as tight as possible. Install
the pre-cut (another personal quality touch) vertical
pieces with thick CA. (CARDEN Step 16)
Fuse05 Another view.
Fuse06 I will be using
the Aero Protect
4 servo Direct Connect Rudder Assembly to take control and drive
the YAK’s rudder. I have designed this assembly so each servo
is connected to and drives the bell-crank assembly. I have taken the
time to build up the assembly now including installing the servos (JR8611a’s)
and will be doing the final dressing of the wires, matchbox installation,
pro-link adjustment and radio programming before installation. More
installation information to follow later.
Fuse07 Another view.
Fuse08 The 4 servo
rudder assembly complete with wires dressed and matchbox installed.
The setup has been powered up centered and setup in the 10X radio.
Very Sweet.
Fuse09 This is an
optional step that does not really save weight but allows for routing
wiring access. Holes have been cut into F2, F3, and F4. For F2 the
holes are 1-9/16 diameter and 1 inch diameter. For F3 the holes are
1 inch in diameter, and for F4 they are 1/2 inch in diameter. It is
very important to take care in how you center them – you must
take into account overlap on the motor box and the truss sides. It
is also very important to take into account the canopy mount for F2.
Fuse10 3/8 square
balsa construction completed for the truss sides.
Fuse11 Both truss
sides balsa construction completed.
Fuse12 Plywood pieces
being installed – make sure you make a left and right truss side
when you do this step. Take great care in aligning the wing tube mount
and stabilizer tube mount. The construction
here is deviating some from the Carden instructions. The plywood mounting
points for the wing hardware is being installed now and is usually
installed in step 22 of the Carden instruction sheet. What is being
shown will also be a different process for setting the wing incidence
than what is described in the Carden instruction sheet. It is important
to read through the complete construction information and review the
CD provided by Carden and decide which direction fits your building
style and building experience level.
Fuse13 Another view
showing the back plywood and hardwood installation
Fuse14 The 1/8 inch
balsa sheeting for the truss sides has been glued up, lightly sanded
and installed on the balsa truss sides. The circle cutter made a very
clean cut in the balsa for the wing tube hole. I cut the wing tube
hole first and then after applying Elmer’s wood glue to all contact
surfaces position the sheeting aligning the wing tube hole properly
on the truss side.
Fuse15 The positions
of F2 and F3 are marked on the motor box plywood.
Fuse16 This is also
an optional step – I add ¼ inch square balsa as a positioning
support for F2, F3, and F4. After the structure is built up it will
also add structural strength to the glue joint area.
Fuse17 The ½ square
hard ash is cut to shape and glued and clamped into position. (CARDEN
Step 13)
Fuse18 Another view
with the clamps removed.
Fuse19 Before gluing
the motor box together it is best to take the time and do as much fabrication
as possible with the flat pieces. The sub floor support has been glued
in place and is positioned parallel to the top of the motor box.
Fuse20 Time to epoxy
the motor box sides to F1, the landing gear plate, and the motor box
rear piece. A lot of clamps are used and extra time is taken making
sure the assembly is square and true. This is a very critical step – take
the time and do it right.
Fuse21 Another view
showing the motor box clamping. The wing tube is only installed to
help alignment it is not glued in at this step.
Fuse22 Another view.
Fuse23 Using a drill
press holes are pre-drilled for the #8 sheet metal screws that are
used on the firewall and landing gear plate.
Fuse24 Predrilling
the screw holes for the landing gear plate.
Fuse25 The #8 sheet
metal screws installed in the firewall mount.
Fuse26 The #8 sheet
metal screws install in the landing gear mount.
Fuse27 In addition
along the bottom of the landing gear plate 3/16 inch dowels are glued
and inserted for additional strength. (See detail in Fuse33 before
doing this step)
Fuse28 A piece of
scrap 3/8 balsa has been added under F1 to fill the small void.
Fuse29 A piece of
3/8 square balsa is added along the bottom of the rear motor box piece
as a mounting point for the plywood curved exhaust deflector that will
be installed soon.
Fuse30 The canister
mount (MTW) is installed along the rear of the landing gear plate and
square to the top of the motor box. This
is a waterjet cut part that can be purchased from Desert Aircraft specifically
for the MTW canister muffler system used on the DA150. The mount fits
like it was designed for a Carden – it wasn’t, that we
know of, but it really makes mounting the canisters very EASY. This
mount will fit the 37% Yak , 40% Edge 540, and 40% Extra 330 with very
little modification if any. The canisters are two 100cc MTW’s.
Fuse31 the motor mount
location was drawn on F1 taking into account the offset and ¼ inch
holes drilled.
Fuse32 The 1/32 inch
thick deflection plate is glued into position. This is optional but
makes for a very smooth exit point. Clamps, Clamps, Clamps.
Fuse33 The mounting
of the landing gear is another area that I deviated from the Carden
instructions. The mounting method for the main gear explained in the
instructions does not need to be changed because it works very well.
For my application – not very smooth grass flying field - I have
found the following method to give me a little advantage to keeping
the structure sound. Quarter inch blind nuts are installed and aluminum
bolts are used for mounting the gear. If you
follow the process I described for mounting the landing gear, it is
important to add additional #8 sheet metal screws through the landing
gear plate into the 1/2 inch hardwood, similar to how they are installed
from the side. The picture does not show them installed but they will
be added. One other note - because the screws will be installed it
is no longer necessary to install the dowel pins as shown in step Fuse
27. (CARDEN Step 14)
Fuse34 The main gear
installed.
Fuse35 The 3/8 square
cross bracing is pre-cut before any assembly and sanded to shape making
identical parts for the top and bottom at the same time.
Fuse36 A close up
of one of the cross braces. The two pieces of wood are pinned together
and then sanded to the shape to make them identical.
Fuse37 The picture
shows some additional work that I do on the truss sides. This
is all optional and only a personal preference. Hardwood
dowels are cut an 1/8 thick and glued in place where the wing incidence
bolts will be installed and for the canopy mounts. The canopy mounts
are counterbored to allow the recess of the screw head and washer.
Fuse38 Close up – the
counterbore will be cleaned up a little better.
Fuse39 The truss side
front and rear bevel has been sanded so when the truss sides are installed
everything lines up at F2 and F5 as shown on the planes. The truss
sides are then placed into position and builder squares put in place
to make sure the structure is built square. Nothing has been glued
yet.
Fuse40 F2 is just
clamped in place to keep the front end in position but it is not glued
yet.
Fuse41 F5 has been
tapered and glued into position at the back end of the truss. This
picture shows F4, F2, and finally F3 glued in place. F3 is added last
just in case it needs to be slide forward or to the rear a little for
proper fit. These slid in perfect. (CARDEN Step
17)
Fuse42 All the cross
bracing is then glued in place along with the corner gussets. Fuse
top side first then fuse bottom side. Wire extension tube and 4 servo
direct connect rudder assembly ready for installation. (CARDEN
Step 18 and 19)
Fuse43 The
gussets that I had installed are being removed and replaced with
gussets that have the wood grain in the correct orientation. The
gussets as per the plans state to be made from 1/8 balsa. That is
being changed to 1/4 balsa and the following note must be followed
as stated: IMPORTANT NOTE: the grain of the 45 degree gussets must
be parallel to the hypotinus of the gusset. In other words it must
be parallel to the long side of the triangle opposite the 90 degree
angle. Speaking with Dennis, from Carden, the second production run,
which is in process now, will include a plastic bag full of the gusset
stock already cut to size with the proper grian orientation out of
1/4 inch balsa. After I rework the fuse I will have pictures re-posted.
The new corner gussets (1.5 inch by 1.5 inch by ¼ balsa) installed.
It is critical the wood grain is in the direction as shown for maximum
structural strength.
Fuse44 The
pictures have been deleted temporarly, see Fuse43 above. The ¾ inch
rocket tubes are mounted using 1/8 balsa fabricated mounts and glued
to the fuse top cross members. Just how I do it – again personal
preference. The ¾ inch rocket tubes are mounted using
1/8 balsa fabricated mounts and glued to the fuse top cross members.
Just how I do it – again personal preference.
Fuse45 Close up of
the tube mount.
Fuse46 The antenna
tubes are also mounted at this time. Scrap 3/8 square balsa is cut
drilled and glued in place.
Fuse47 Another view.
Fuse48 Time to get
the rudder assembly mounted. The process shown here is how to make
the assembly removable if needed . Additional ¼ x ½ bass
wood is added along the front and rear rails and in the truss sides
behind the bellcrank.
Fuse49 This is the
rear mount made from ½ x 1 inch bass wood and triangular supports.
This will be mounted on the rear motor box wall.
Fuse50 Rudder assembly
mounting points being added,
Fuse51 Rudder assembly
mounting points being added to the aircraft structure.
Fuse52 The mounting
holes have been added to the rear mount and the rudder assembly attached.
The assembly has been clamped in place and the rear mount is glued
to the rear of the motor box. Remember the plane is upside down on
the plans!! Up is down and down is up – think about it……
Fuse53 Mounting points
for the rudder assembly have been drilled and blind nuts installed.
Here additional support plates are added to one of the rudder assembly
mounting rails.
Fuse54 A close up
view of the support mount.
Fuse55 Aero Protect
Direct Connect 4 servo rudder assembly installed.
Fuse56 Another view
of the installed rudder assembly.
Fuse57 Another shot
of the mounted assembly – I think I might need to use this picture
in an ad !
Fuse58 Front hatch
sheeted. These round parts take a little planning when applying the
weight while the polyuretane glue is curing. The weight has to be added
equally or it will rotate out of the saddle. (CARDEN
Step 12A)
Fuse59 Bottom deck
pieces sheeted. (CARDEN Step 12B)
Fuse60 Bottom deck
pieces with the center block removed.
Fuse61 Sheeted turtle
deck. Be CAREFULL with this one. The part is round and has a steep
angle when placed into the saddle during glue curing. I would recommend
if using polyurethane glue and you have a habit of adding a little
moisture to the part to activate the foaming – don’t do
it on this part. As the glue foams the part will slide. Yes, I was
lucky enough to do the part twice. I do not mist it but while I was
sheeting all it did in Florida was rain. The part did not slide much
but I trim the wood fairly close before gluing and a little movement
gave me grief. Second time through – no problem. (CARDEN
Step 12D)
Fuse62 Bottom deck
sheeted. (CARDEN Step 12C
Fuse63 The
bottom motor box plywood piece has been cut to accept the canisters
and air flow through the tunnel and epoxied in place. Masking
tape is used to hold everything tight while the epoxy cures.
Basically, a one inch frame is what is left. Also notice the
engine standoffs have been cut to size and drill to accept the ¼ x
20 engine bolts. Take some time to cut them to the proper length.
Fuse64 The wing tube
has been glued in place. Take a lot of time and make sure the wing
tube is square front to back and top to bottom – then epoxy in
place. I use 30 minute epoxy on each contact point. (Carden
Step 21)
Fuse65 The wing tube
has been epoxied in place and trimmed and sanded flush to the fuselage
side truss sheeting.
Fuse66 After the tube
has been epoxied in place I take a disposable brush and add some additional
epoxy around all the contact points. Not a lot just a thin layer.
Fuse67 The DA150 has
been mounted with MTW headers and canisters installed. For a proper
fit the rear air deflector that was installed in stage Fuse32 needed
to be removed and redesigned because the rear of the canisters were
hitting the deflector and not allowing them to back far enough. Also,
take note of the semi-circle cut outs for the exhaust exit pipes. If
everything is done correctly the exhaust system fits perfect without
having to trim the length of the header pipes. After speaking with
Desert Aircraft it is very important for the engine transition through
the mid range to have the header pipes the length shipped from the
factory.
Fuse68 Another view
of the reliefs cut for the canister exhaust exit pipes. Also notice
the additional crews added to the landing gear bottom plate as explained
earlier.
Fuse69 Rear of the
canisters with the curved deflection plate removed.
Fuse70 Close-up of
the engine standoffs.
Fuse71 A new air tunnel
exit is being fabricated. To allow a little more space for the rear
of the canisters the sub floor behind the wing tube is being brought
up 3/8 of an inch. I will try to explain the design change. A piece
of 1/8 lite ply is being added at an angle as the rear air tunnel exit.
The piece covers the back of the air tunnel from the sub floor down
to the bottom of the motor box back plate. The piece of lite ply measures
out from the motor box back plate 1 – 3/16 inch at the sub floor.
In addition, two pieces of 3/8 square balsa 3-5/8 long are added on
top of the sub floor 3/8 square supports to give a little more head
space to the canisters in the back. A piece of 3/8 square balsa is
then added across the motor box and in front of the additional 3-5/8
inch pieces to support the sub floor cap. The following pictures will
help with the expalination. This picture shows the raised sub floor
being epoxied and clamped in place.
Fuse72 A closer view
of the rear area for the canisters. This picture is from a bottom view..
Fuse73 Another view
to help explain the tunnel fabrication.
Fuse74 Tail wheel
mounted. (Carden Step 20)
Fuse75 Support the
fuselage so it reads 0.0 or level before setting the wings to 0.0.
Remember make sure the fuselage is level front to back and side to
side. (Carden Step 22)
Fuse76 Setting the
wing incidence using the long robart bar and digital protractor accurate
to a 10th of a degree. As you can see 0.0 incidence.
Fuse77 To make marking
the holes in the fuselage easy for drilling a 3/8 square balsa block
it lightly CA’ed in place along the trailing edge of the wing
holding the wing in the correct position. After the incidence has been
set and the holes drilled the block can easily be removed and any marks
left filled with body filler and sanded smooth.
Fuse78 The balsa block
is also used to hold the stabilizers in place after the incidence has
been set to 0.0.
Fuse79 To mark the
fuselage for the anti-rotation screws a 10-32 screw head has been modified
by cutting off the head and grinding a centered point on the other
end. Thread the pointed 10-32 screw into the wing blocks front and
back and slide the wing on the wing tube. Carefully bring the wing
up to the fuse making sure the trailing edge is in contact with the
locating block that has been glued in place. With everything aligned
slide the wing against the fuselage to make indents for the anti-rotation
screw locations.
Fuse80 Front 10-32
screw with washer in place with the wing. A larger washer will be used
for the actual mounting of he wings.
Fuse81 Rear anti-rotation
mounting screw.
Fuse82 Wings and horizontal
stabilizers mounted.
Fuse83 Stabilizer “L” bracket
mount location is drawn on the fuselage 1/8 balsa truss covering and
cut out. Remove the balsa flush with the 3/8 plywood hard point mounted
earlier.
Fuse84 “L” bracket
placed in the cut out.
Fuse85 “L” bracket
installation on the stabilizer is covered in the “elevator” section.
Here the stabilizer is installed with the “L” bracket.
After making the cut out through the balsa to the hard point the stabilizer
was installed with the “L” bracket installed. The fuselage
mounting point is then marked and drilled. My preference is to install
a blind nut inside the fuse and use a 6-32 socket head cap screw with
lock washer and washer for both mounting points of the “L” bracket.
One into the stabilizer and one into the fuse. Even though the lock
washers and washers are used I will still use blue locktite on the
screws during final installation.
Fuse86 It is time
to get some shape on the fuselage truss assembly. The bottom deck is
now installed. Aliphatic glue is used to allow some time to position
the piece and get it taped down. Remember before installing any of
the bottom deck pieces the 1/16 inch balsa strips must be glued in
place first on the bottom edges and the front and back as well. Take
a little time to make sure they are all done and look over the plans
for the detail for each piece. (Carden Step 24)
Fuse87 The tail wheel
assembly has been installed and the tape removed from gluing the bottom
deck in place. (Carden Step 20)
Fuse88 The front bottom
deck pieces are just set in place to see how all will fit. Notice the
bottom rounded piece that goes over the landing gear has been cut into
two pieces with 1/8 inch balsa end caps put in place at the cut. The
piece has been separated to allow for a removable section of the top
of the gear.
Fuse89 The ¼ inch
balsa cross grain sheeting has been cut and epoxied in place to close
off the canister tunnel.
Fuse90 The cut out
for the canister tunnel air exit has been made. This one is 6 inches
by 2.25 inches wide.
Fuse91 The bottom
deck pieces has also been cut for the exit hole. This cut is actually
oversized by the dimensions of the balsa thicknesses of the pieces
that will need to be added to cover the exposed foam. Careful cutting
with a miter saw makes for nice square cuts.
Fuse92 The bottom
deck pieces glued in place with aliphatic glue and taped in place. This
picture shows a small problem I will need to correct through carefull
sanding and shaping. The bottom deck should actually be glued in place
with a small indent not flush to the truss side as shown. It should
match up with the back of the front quarter round bottom deck pieces.
Remember to use the cowl ring as a guide when installing the foam deck
pieces.
Fuse93 Another view
of everything taped in place.
Fuse94 VERY
IMPORTANT: Originally I was showing the back area of the bottom deck
being a removable hatch. After converstaion with Dennis from Carden,
I have decided to glue the hatch in place and not make it removeable.
Disreguard any following pictures where the hatch is shown it is
in the process of being changed to permanent. Do to the loads that
can be put on the tail surfaces with 3D flying the full box structure
must be kept intact for maximum structural support. DO NOT MAKE A
REAR HATCH. Include a couple of fish lines in throught the extension
tube and tape them to the side of the fuse through the balance of
the build and finishing.
Fuse95 Removed.
Fuse96 The very back
piece of the extension has been cut from the rear hatch and the tail
wheel relief has been cut out. The block has been glued in place with
a ¼ inch balsa header added that will be sanded to shape to
match the rear hatch.
Fuse97 Front and back
balsa pieces have been cut and glued in place to start sheeting the
canister air exit hole.
Fuse98 Another shot
of rear tail wheel foam piece along with a shot of one of the fuselage
mounting pieces for the rear hatch.
Fuse99 The removable
piece that fits over the landing gear has been sanded to shape with
the back balsa sheet added along with sheeting the entire bottom of
the piece because it will need to be sealed the same as the fire wall
and exposed areas that may come in contact with gas, oil, and exhaust.
Fuse100 The landing
gear relieve has been cut out. The cut out size also allows for filling
in the tunnel cut for the gear with balsa sheeting. Notice the way
the part was cut allows the balsa end plate to extend past the gear
and down giving a nice finish look against the curve surface glued
in position behind the gear that stays as part of the fuselage.
Fuse101 Bottom view
of the part showing the cut out tunnel for the gear.
Fuse102 Test fit
of the removable assembly.
Fuse103 The removable
part with the mounts (same as how the rear bottom deck removable cover
was done) in place.
Fuse104 Bottom view
of the part finished with all sheeting installed.
Fuse105 Removable
cap installed and the bottom deck finished for now.
Fuse106 Tail wheel
area sheeted and complete.
Fuse107 Top deck
glued (aliphatic glue) in place and taped down. I added small balsa
blocks along the side to keep everything lined up. The blocks are lightly
CAed in place and then removed. Starting to take shape. (Carden
Step 25)
Fuse108 A picture
inside the fuse – just because it looked cool.
Fuse109 Making the
hatch parts. (Carden Step 26B)
Fuse110 Hatch mounts
screwed in place. They were then removed and wax paper installed for
the next steps to prevent making a permanent assembly !!
Fuse111 ¼ inch
balsa front cap piece being installed, glued (aliphatic), and taped
in place.
Fuse112 ¼ x ½ inch
basswood being glued to the hatch hold downs. Note the wax paper added. (Carden
Step 26C)
Fuse113 1/8 inch
dowel pins installed through the basswood rail and into the hatch hold
downs.
Fuse114 Front hatch
in position with ¼ x ½ basswood doubler installed and
cut into the front hatch foam. Take some time and get this lined up
properly !!! (Carden Step 26D)
Fuse115 The slots
for the ¼ x ½ basswood doubler cut into the foam. Make
some nice tight cuts. (Carden Step 26E)
Fuse116 Close up
of the front hatch epoxied in place to the basswood doubler.
Fuse117 Front hatch
glued onto the basswood rails and taped in place. The front locating
dowel pins have been glued (aliphatic glue) in place. (Carden
Step 26F)
Fuse118 The plywood
mounting tab has been fabricated and installed with epoxy and dowel
pins through the balsa front cap and into the plywood fuselage F2 piece.
Very sweet setup.
Fuse119 The fuselage
taking shape and getting big ? ! Elevators have been installed and
the aluminum tube drilled and taped with the number 6 socket head cap
screws, lock washers, and flat washers installed. Final construction
the screws will also carry a little blue locktite.
Fuse120 Starting
the balsa build up for the hatch. Here the ¼ x 1-5/8 x 26-7/8
hatch rail has been glued to the ¼ x ½ basswood rail. (Carden
Step 26G)
Fuse121 Picture of
the front installation.
Fuse122 Since the
bottom hatch is being permanently glued in place “fish” string
has been sent down the extension wire tube and threaded out each side
of the stabilizer servo wire entrance holes on the fuse. I looped the
string through the stabilizer tube and tied them both sides together
so they would not slip back inside the fuse. After the servo extension
wires have been run and you remove your stabilizers for travel make
sure you put some sort of a keeper on the wires to prevent them form
finding there way back into the fuselage. One way is to take a piece
of 1/8 plywood and cut a slot into it the width of the servo wire (a
little tight) slide it on behind the connector and that will keep them
from going back in.
Fuse123 The servo
wire “fish” lines have been tied off up front as well.
Fuse124 The balsa
pieces for the hatch sides have been glued (aliphatic glue) and clamped
in place.
Fuse125 Special
Note: for the people building from the first production run it is
required to extend the ¼ x 1-1/8 x 11-1/2 inch balsa piece
to 18 inches. Fabricate and glue on the extension. This is required
to have enough material to shape the contour of the canopy side buildup.
The YAK-54 second production run forward will have the balsa stock
cut to the correct dimension.
Fuse126 Using a long
straight edge draw a “do not cross line” from the front
hatch deck to the turtle deck as a guide for sanding the canopy side
contour.
Fuse127 A picture
looking back towards the turtle deck for the “do not cross line”.
Also note installation of some temporary cross braces across the canopy
sides to support them during shaping.
Fuse128 The canopy
side contour being shaped. It is recommended to install the wings and
draw a pencil line along the top of the wing root to give you another “do
not cross” reference line when shaping the canopy sides.
Fuse129 Rough sanding
is done for the shaped sides. The inside surface will also be shaped
to contour and remove excess material using a dremel tool. The build
up wall thickness will be kept to around a ¼ inch thick. Pictures
will follow.
Fuse130 Another picture
of the rough contour shape. The cowl ring is just resting in place
to make sure the shaping is done equally.
Fuse131 The vertical stabilizer/rudder has been hinged, edges beveled
and installed on the fuselage. Take your time to get the alignment
correct and remember the dowel.
Fuse132 Another view of the vertical stabilizer installed.
Fuse133 Time to get the cowling taken care of. The cowl has been trimmed
with a Dremel tool and small ¾ x ¾ x 1/8 plywood tabs
are being epoxied in place for the button head cowl screws.
Fuse134 Another view showing the cowl halves taped together before
drilling the holes.
Fuse135 Inside view with the plywood pads glued in place.
Fuse136 The cowling half screw holes drilled and screws installed.
I use a nylon washer under the button head screws to prevent the paint
from marring after final assembly. The nylon also acts like a lock
washer.
Fuse137 Inside view of the cowling with the blind nuts installed.
Fuse138 The reinforcing balsa strips have been added along the joint
for the motor box bottom plate and the ¼ x ½ cross brace
along the top has been added. In addition, I have added several ¼ x ½ structural
members in the motor box because I am making a removable top hatch
area of the motor box. This is optional and something I like to do
to gain access to the smoke, throttle servo, and ignition. If you go
this direction it is very important that the structural pieces be added
to add strength to the motor box. The sub floor in this case also adds
a lot of rigidity.
Fuse139 The motor box top plate has been cut and the none removable
pieces (front and rear) are being epoxied in place.
Fuse140 Cutting out the rear turtle deck that goes around the vertical
fin. Use the templates supplied and sand and fit, sand and fit, sand
and fit, until you get it right. It is not hard just takes a little
time.
Fuse141 Bottom view after shaping.
Fuse142 The top mounting L brackets in place. It is very important
to back up the 1/8 plywood with either a scrap piece of 1/8 plywood
or in my case I added a piece of ¼ x ½ basswood under
the 1/8 plywood top plate to allow the #8 sheet metal screw to bite
into some material. DO NOT just install the #8 screws in the 1/8 plywood
only. The removable screws are 6-32 with washer and lock washer into
a blind nut in the cowl ring.
Fuse143 Lower L brackets installed – same as the top ones again
this time add a back up piece behind the 1/8 plywood and if you would
like the ¼ plywood cowl ring to give the #8 sheet metal screw
material to bite into and the #6 blind nut the thickness needed.
Fuse144 I make part of the top motor box removable to allow access
to the ignition and battery packs. It is very important that if you
make the top removable that you add plenty of ¼ x ½ basswood
to frame the opening and allow for several tie down screws.
Fuse145 The hardwood ball driver guide installed. Take some time to
get everything lined up. Make sure you install them before gluing
the cowl to the cowl ring or you will not be able to remove the cowl
from
the fuse. Think about it – it will make sense to you.
Fuse146 Another view of the top mounting brackets installed,
Fuse147 Before fitting the cowl I tape 1/16 inch scrape balsa around
the edge for the proper spacing of the cowl away from the fuse.
Fuse148 Another view of the spacers
Fuse149 The cowl on and ready for tacking in place. You have a couple
of choices here. The cowl can be glued onto the cowl ring and remain
one piece or you can cut the cowl ring after gluing it in place to
make the cowl two pieces. In fact if you want to make the cowl one
piece you can glue it together before installing the cowl ring and
not even use the button head screws. Mine will stay one piece with
the button head screws because I like how it looks.
Fuse150 That is one big cowl !! The fuselage is really taking shape.
Fuse151 Carefully drill the ball driver access holes. I used a flashlight
on the outside of the cowl shinning through to see the hole in the
guide. After carefully marking the hole locations drill and check for
alignment.
Fuse152 The ball driver inserted and removing the cowl screw. In this
picture you can see the fillet formed with epoxy and micro balloons.
What you do not see is the other side of the cowl ring has been glassed
in using fiberglass stripes and finishing resin to add strength to
the structure. I will also be adding fiberglass stripes to the front
side of the cowl ring with the cloth extending at least 1 inch onto
the cowl and covers the epoxy fillet and onto the cowl ring.
Fuse153 The cross grain balsa sheeting is being added to the cockpit
area. The instrument housing is only set in place and the area where
the pilot will be placed is still left open. I prefer to install the
pilot onto a removable panel to allow access to the pilot, pilot glasses,
and instrument panel after the canopy has been glassed in place. This
is not a requirement only my building preference.
Fuse154 To start framing the removable area I use ¼ x ½ basswood
rails under the 1/8 inch balsa sheeting.
Fuse155 The removable panel area cut to size, pilot setting in place
with some of the balsa sheeting rough sanded to shape.
Fuse156 The underside of the removable panel is also framed with ¼ x ½ basswood
which fits very tightly into the opening.
Fuse157 The side flanges of the removable panel have been cut off and
glued into place finishing the cockpit balsa decking construction.
The cross grain balsa pieces have all been rough sanded to shape.
Fuse158 The ¼ inch thick balsa rear canopy piece C2 has been
cut to shape and installed to the cockpit structure.
Fuse159 The pilot has not been glued in – he will be installed
after the balsa has been painted. The instrument panel has been glued
in place. Again my preference, I have added a piece of scrape balsa
around the instrument housing to cap off the instrument panel when
it is installed and cover the seam line that otherwise would be visible.
Fuse160 Another view of the instrument housing with the additional
balsa extension piece glued in place.
Fuse161 Getting ready to paint the inside cockpit with automotive trunk
paint. I mask off the area where the pilot is glued in so I have a
good gluing surface when it is time to install him. To do that I place
pieces of tape onto wax paper and trace the bottom shape of the pilot
onto the tape. Using an exacto knife the shape is cut out which creates
a paint mask. Peel away the wax paper and apply.
Fuse162 The tape mask installed.
Fuse163 To finish off the cowl installation fiberglass has been installed
not only on the
Fuse164 Canopy in place to mark the cut lines.
Fuse165 Close up of the cut lines.
Fuse166 Cockpit area has been painted with automotive trunk paint -
pilot and instrument panel mask off tape removed.
Fuse167 Another view of the cockpit area.
Fuse168 Canopy has been trimmed to size and the balsa sides relieved
(sanded) the depth of the canopy thickness for a flush fit. Canopy
has been glued in place with RC56 canopy adhesive. The next step will
be a little filling and some final sanding of the hatch canopy cockpit
area prepping for glassing and finishing resin.
Added: December 4, 2005
Fuse169 The tail wheel is installed which requires a small relieve
to be sanded into the fin trailing edge and the rudder leading edge.
Fuse170 This is the bottom of the canopy front section that goes over
the gas tank. Due to the canister tunnel being installed the gas tank
may now come in contact with the front foam section of the canopy.
Using a soldering iron and copper wire the foam was cut out to give
a relief for the gas tank and allow for it to expand.
Fuse171 Another view showing the depth of the cut.
Fuse172 The gas tank installed with T fitting and the throttle servo
installed. The front notch is for the ignition wires to come through.
Fuse173 The receivers are installed with the wiring starting to go
in. The antennas still need to be placed inside the antenna tubes that
run along the bottom of the fuselage. After everything is installed
and checked out the wires will be dressed nicely.
Fuse174 Here we go, final assembly before tear down for sanding, covering,
and painting. DA150 and canisters installed, ignition module in place,
with top hatch securely screwed down, and ignition wires wrapped in
plastic spiral wrap that will be added to the web site for sale shortly.
The only thing that is not installed is the batteries, switches, and
regulators that will be coming soon. Fromeco setup will be used.
Fuse175 Close up of the motor area. Notice a small radius relief cut
has been made for clearance of the right (left in the picture) exhaust
stack.
Fuse176 The top hatch has been shaped and sanded and sanded and sanded
and sanded. The canopy mounting area was recessed for a flush mount
to the hatch. Take the time needed to fill and sand everything to shape
before glassing. Half ounce fiberglass cloth was used along with ZAP
finishing resin. The fiberglass cloth took a couple of applications
of the finishing resin to fill the weave with a little wet sanding
in between coats. The results givie a very nice surface for prime and
paint.
The new kits have a new canopy that extends down and eliminates the
need for all the balsa build up shaping and sanding. The other benefit
is the assembly turns out to be lighter.
Added: June 13, 2006
Fuse177 The front motor box has been painted with flat black dope
to fuel proof it Notice the additional mounting hardwood to screw
he hatch
in place. Keep the motor box area solid and strong. The DA ignition
module has been mounted on foam and velcroed in place under the top
hatch. Fromeco batteries, regulators, and badger switches are used
throughout the plane. This shot shows the mounting location for the
ignition regulator in the motor box.
BALANCING The plane has been sanded to 600 grit, covered with Ultracoat,
Kirby Graphics, and PPG Concept Paint. It is time to balance the
plane. Balancing the YAK was very easy. I have had several conversations
with
Dennis of Carden throughout the build and the latest update was the
CG for the plane has a wide range. The CG could be moved back to
the center line of the wing tube without any concern. Here the plane
is
lifted by the wing tube. Can you say easy.
Fuse178 To balance the plane the battery packs were placed in the
front motor box area. Two Fromeco Peerless 4800mAh packs (one for
each receiver)
and one 2400mAh Peerless for the ignition. The method for mounting
the ignition regulator can also be seen here. The regulator has a
foam pad and held in place with the Velcro, In addition, I add a
screw through
the front mounting hole with a small piece of fuel tubing between
the regulator board and the wood side to also help reduce vibration.
Fuse179 Inside the plane. Dual receivers with dual regulators and
the 4 servo direct connect rudder system. The SWB pull pull tensioners
were added which made
the setup really easy to adjust. Fromeco Badger switches are also visible and
the dual aileron pigtails can be seen on each side of the fuselage. Again,
the receivers and regulators are foam mounted and held in place with
Velcro to help
reduce vibration.
Fuse180 Another inside picture
Fuse181 Another inside picture
Fuse182 This picture shows the 50 oz tank installed and the throttle servo
location.
Fuse183 After the first couple of flights a modification was made to the front
carb plate. I spoke with Brian Hoofmeiur from Desert Aircraft about the concern
of prop blast directly hitting the vent hole. The recommendation is to add
a 90 degree fitting to the hole to prevent the direct blast and allow the diagram
to work properly. The fitting is actually the same fitting that is used on
the
side of the carb for the gas inlet. The fittings fits perfect in the hole of
he carb plate.
Fuse 184 The fitting has been shortened so it just extends through the back
of the carb plate. I used a couple of steel balls different diameters and a
small
hand press to flair the back side of the fitting. No soldering required !!!.
Fuse 185 The extended flaired part has been ground down with a dremel tool
to be flush to the back side.
Elev01 Step one – transfer
the hinge line from the plans to the foam cores for working out servo
bay locations.
Elev02 The hardware
will be dual 8611a’s on each elevator half, rocket city RCL70
swivel clevis mount, 2 inch Pro-link, AirWild 1.25 inch servo arm with
RCL87L (Left Hand Thread) ball link – All available through Aero
Protect Corporation. The hardpoint mount in the control surface will
also be mounted 1 inch from the servo output shaft and not 1.25 which
greatly reduces the amount of angular offset that occurs when the servo
arm rotates through its full motion. Only a suggestion.
Elev03 Stabilizer
tubes with balsa end caps installed to prevent glue from entering during
installation. (CARDEN Step 11B)
Elev04 Servo shaft
center points marked for each servo. I rotated the servos 180 degrees
from what is shown on the plans to bring the servo arm closer to the
control surface and allowing a shorter pro-link.
Elev05 The templates
(well used) and bent wire forms used in the soldering iron to cut the
bays.
Elev06 Servo bays
cut. An alternate method that Carden uses is
to draw the servo bay shape on the foam and cut completely through
the foam core using a vertical sawing motion with a 3/8 inch wide snap
off blade razor knife. (CARDEN Step 11A)
Elev07 ¼ x ½ hardwood
servo mount slots cut.
Elev08 Servo mounts
installed. Prior to sheeting the area above the mount that extends
past the servo bay is back filled with foam. When I do the wings I
will get a picture prior to sheeting. The picture
shows the servo mounts 90 degrees from what is shown on the plans.
Either way is acceptable, however, if you choose to install as shown
in the pictures, the space above the wood mount extending out past
the servo bay should be back-filled with
scrap foam and glued in place using alaphatic glue such as Tite Bond
II. After the glue has set, sand it flush to the core surface prior
to sheeting.
Elev09 After sheeting
the wood was trimmed and sanded flush to the cores. Placing the cores
back in the saddles and aligning the lines the hinge line was redrawn
on the sheeting along with the servo shaft centers. Always a good idea
to take accurate measurements and write them down on the plans for
the hole locations – the end result is servo bays cut dead on. (CARDEN
Step 11D)
Elev10 The leading
and trailing edges glued and taped in place.
Elev11 The rudder
relief cut made on the elevator. The foam still needs to be sanded
flush to the cut lines.
Elev12 Stabilizer
and elevator trimmed and sanded.
Elev13 The 1/8th inch
thick balsa root cap for the stabilizer has been cut a little oversized
with the servo wire exit hole also cut out.
Elev14 The full root
1/8th inch thick balsa root cut and glued in place using aliphatic
glue and taped tight.
Elev15 The balsa roots
have been sanded to shape pulling together he parts needed for the “L” bracket
hard point.
Elev16 The 1/8th inch
dowel pieces have been cut with the mounting holes drilled into the
plywood hard point.
Elev17 One hard point
all set for installation. The 1/8th inch dowels have been epoxied in
place and the #6 blind nut installed. Notice the “L” bracket
is installed with a ¼ inch overhang. The overhang is for the
1/8th inch balsa root of the stabilizer and then the relief of the
1/8th inch balsa fuselage truss side that will allow the “L” bracket
to mount against the fuselage plywood hard point. Reference: Fuse83
Elev18 The “L” bracket
and hard point installed with 30 minute epoxy. Remember to put the
Vaseline on the bottom of the extended part of the screw so it does
to become permanent .
Elev19 A closer view
of the hard point installed.
Elev20 A ½ diameter
brass tube that has been sharpened is used to cut cleanly through the
balsa and foam to the tube socket in the elevator. Take your time and
measure the location for the hole – it is parallel to the hinge
line 4.5 inches in from the foam root. (Finishing
Carden Step 23)
Elev21 The hard-point
for the tube is a ½ diameter dowel with a blind-nut on the side
to go against the tube. The hard points are then
bored out with a 3/8 inch forestner bit to recess the socket head screw.
To keep everything aligned I drill a relief ½ inch in diameter
in scrap wood that has been clamped in place. The forestner bit is
replaced with the drill for a number 6 screw and drilled through.
Elev22 The underside
of the stabilizer with the L-bracket installed and the tube screw hard-point
in place. It still needs to be sanded flush to the surface.
Elev23 Elevators have
been installed and the aluminum tube drilled and taped with the number
6 socket head cap screws, lock washers, and flat washers installed.
Final construction the screws will also carry a little blue locktite.
Elev24 The hard point
dowel has been sanded flush to the surface and the cut lines for the
elevator has been drawn. Remember the elevators have ½ balsa
leading edges and the stabilizers have ½ inch trailing edges
so you are cutting an inch of material out along the hinge line.
Elev25 The cuts completed
and the waste material removed. Take care to make clean square cuts
and sand flush to your cut lines.
Elev26 Leading and
trailing edges for the hinge line have been glued (aliphatic glue)
in place and taped. In addition the 1/8 inch balsa caps have been glued
in place forming the elevator counterbalance section. The balsa tips
have not been glued on yet.
Elev27 Another view.
Elev28 The ½ inch
stock has been sanded to shape and is ready to be hinged.
Elev29 and Elev29a The elevator and stabilizer has been marked and
the hinge points drilled. I am using Robart hinges and used the Robart
drill guide with 3/16 inch drill bite. I also double up (make them
closer together) on the hinges at the end points – only my preference
not a requirement from Carden. Draw a center line on the trailing edge
of the stabilizer and the leading edge of the elevator. Measure and
mark each hinge point location – be very accurate for the two
parts so everything lines up nice when the surfaces are hinged. I press
in the pencil point a little at the center to give a starting hole
for the drill bit. I tried something a little different this time and
used a 3/16 Dewalt drill bit for wood that has a sharp starting tip.
I did not find the bit wanting to wonder as it drilled the hole. Only
go through the wood and a little way into the foam. Mark your drill
bit with a piece of tape to control the depth. Take your time.
Elev30 A little fuzzy – but here you can see the bevel lines
have been drawn. To mark the bevel I make a small template. Because
the surface tapers root to tip the bevel lines are not straight on
the edges. I make a template from stiff paper that matches the bevel
for the root end of the surfaces. In this case the thickness of the
surface –cord – by the thickness of the leading or trailing
edge 1/2 of and inch. Mark the center and draw the bevel. Place it
on the root edge of the surface for the bevel and draw it on. Use the
same template for the tip end and connect the two ends with a long
straight edge root to tip. You will see the line is not parallel to
the edge. Reference Rud10 for a better picture of the bevel.
Elev31 I use a razor plane to make the bevel but for the rudder I sand
the bevel shape by the counter balance to make room for the razor plane.
Elev32 The hinge area has been beveled and the elevator tip glued in
place using aliphatic glue. See Wing33 and 34 for shaping the elevator
tip.
Elev33 See Wing33 and 34 for shaping the elevator tip.
Elev34 See Wing35 for a tip how to uniformly contour the tip to a nice
round shape.
Elev35 The elevator servo control horn mounting locations being marked.
Elev36 The elevator and aileron control surface hard points ready for
drill and tapping for 8-32 hardware.
Elev37 After the hard points have been drilled and tapped I countersink
the back side of the block to allow the flat head screw fit flush and
give maximum contact area for strength. When the blocks are epoxied
in I also add glue to the threads and under the screw head before installation.
Elev38 The control hard points epoxied in place.
Elev39 View of the elevator hard points installed.
Elev40 Servos installed to check for proper fit and work out servo
extension lead lengths
