K&A Models Ki-46 “Dinah” Specifications of model as built Wingspan: 43.5 in
by Greg Mehojah (gmehojah3@comcast.net)
Being a scratch builder I am used to starting with a large stack
of balsa and ply, knowing that I have a lot of work to do to complete
a project. Upon opening the Ki-46 kit, I was surprised to find
the contents surprisingly sparse, and I knew this would be a quick
build project.
The kit contains a gorgeous epoxy/fiberglass fuselage with the
vertical tail section molded in, feather cut foam wing cores,
clear raised-line canopies, ABS cowls, nacelles, and belly pan,
instruction booklet, and a bag of balsa and ply parts. What I
didn’t realize from the first inspection of the fuselage is that
the panel lines are already molded in! Furthermore, the ABS nacelle
components have a recess in them that can easily accommodate either
plug-in landing gear, or 1/2A Robart Retracts.
I mix up my building sequences depending on the kit. For the Ki-46,
the wing is the most involved part of construction (the rest of
the kit takes no time at all). So, I began by first sheeting the
wings, and while the wing sheeting was weighted down and drying,
I primed and prepared the fuselage. Doing this speeds up an already
quick build.
CONSTRUCTION
Wing
Construction begins with preparing the wing cores for sheeting
with the included 1/16th balsa sheets. A _ inch portion of the
trailing edge must first be removed. Place the cores in their
saddle, and measure from the SADDLE (not the wing trailing edge)
inwards _ inch at the root and the tip. Remove the wing from the
saddle, and using a metal straight edge and a sharp hobby knife,
slice this section off the wing core. This is done to remove the
very thin trailing edge and provide a nice solid area for sheeting.
Do this for the other wing core, then sand the cores lightly to
remove any cutting lines, irregularities, etc. Use 220 grit paper
on a block to keep the cores uniform in shape.
Next cut the motor wire and servo wire channels into the wing
according to the plan included in the instruction book. The instructions
recommend using a basswood block with sand paper glued to it to
make a uniform channel, but I chose to use my Dremel with a router
bit attached. Just be careful not to go to deeply or remove too
much foam. I chose to wait until the wings were sheeted to cut
the aileron servo wells as is my personal preference.
Now to skin the wing. Take four of the 1/16th sheets out of the
parts bag, trim them with a straight edge so they butt join together
nicely, and tape them together with masking tape. Don’t glue them
together! After joining the four sheets together, use the wing
saddle blanks to draw the outline of the wing onto the sheets
slightly larger than the blanks, and cut a top and bottom wing
skin. Grab four more 1/16th sheets from the parts bag and repeat
for the other core. You should now have four wing skins joined
together by only masking tape. Be sure to cut your sheeting so
that the masking tape is on the outside of the core. Mark another
_ inch line inwards from the trailing edge of each piece of sheeting
as an alignment guide to the core. Remember that _ inch that you
removed from the cores? The sheeting will make up that _ inch
section when you sheet the wings.
Next, tape the separate wing skins to each other at their trailing
edges leaving a slight gap between them. This is done so you can
fold the skins around the cores like a pita pocket. Mix up some
slow cure epoxy and smear it onto both wing skins (the insides
of course). Take a squeegee or old credit card to remove as much
of the epoxy as you can; you just want the balsa to have a wet
look. Place the sheeting into the saddles, and the cores inside
the sheeting keeping the trailing edge of the core lined up with
the line you drew on the sheeting earlier. Mix up another batch
of slow cure epoxy with enough micro balloons so that it’s a paste-like
consistency. Brush this onto the section aft of the trailing edge
line (this fills the little gap between the sheeting and the core).
Do this for both wings, and then stack heavy weights on top of
the saddles/cores for 24 hours.
Remove the wings from the saddles, pull off all the masking tape,
and sand the sheeting flush with the cores. Also cut the sheeting
for the motor mount plates. The sheeting is removed along the
top and bottom of the wing from the leading edge backwards towards
the trailing edge. Attach the leading edge, cut out the ailerons,
trim and cap them according to the instructions, and attach the
ply control horn plate to each one. Attach the tip plates and
sand to shape.
Sand the root of each wing so that they will fit nicely with a
1” block under each tip, and join the wings together with epoxy.
Be sure that you follow the directions and cut the servo/motor
wire exit holes into the top of the wing halves prior to joining
them together. I used 5 minute epoxy to do this, but you may wish
to use a slower curing epoxy to ensure that things are all lined
up properly.
Finally, cut and attach the aileron control horn plates, and the
bolt plates to the bottom of the wing. Also carefully measure
and trim the trailing edge so the wing seats nicely to the fuselage.
At this point I chose to glass the wing with .59 oz Parson’s fiberglass
cloth and epoxy. I don’t cover this process, but Jim Ryan’s (home.fuse.net/ryan)
website contains instructions for glassing balsa surfaces. While
the epoxy/glass cured, I moved onto the fuselage construction.
FUSELAGE
CAREFULLY wet sand the fuselage with 400 grit wet/dry paper to
remove the slightly raised fuselage seam (along the top and bottom
lengthwise). And only wet sand the fuse to remove the shine. Sanding
more than is required will result in pin holes throughout. Begin
by spraying a LIGHT coat of primer onto the fuselage. I use cheapo
automobile primer from the local auto parts store. This first
coat of primer reveals imperfections in the fuselage so that they
are easier to correct. Good luck finding any imperfections! Squadron
putty (available widely at hobby shops) is a great method for
filling any pin holes and other imperfections in glass surfaces.
After you have the imperfections corrected and wet sanded, add
another coat of light primer to the fuse and your ready for final
paint! Prior to final paint, I wet sanded my fuselage LIGHTLY
with 600 grit wet/dry paper, just to knock off any loose primer
and provide a nice smooth finish for paint.
[wingbolt.jpg]
Using epoxy and micro balloons , attach the wing bolt blocks into
the front and rear of the fuselage. Align the wing to the fuselage
and drill the rear of the wing through to the wing hold down block.
I chose to use blind nuts and matching nylon bolts rather than
tapping the hold down block, but either method works well. Bolt
the wing at the rear, align the wing to the fuse at the front
and drill the front in the same fashion.
MOTOR MOUNTS
The motor mounts consist of three pieces of wood. These are joined
together with CA and then slid into the slots cut into the wing.
I took the advice detailed in the instructions to center the motors
to the cowls (the motors are off-center as built straight from
the kit), and cut new motor pylons _ inch taller using the template
in the instruction booklet.
[frontmount.jpg][builtmount.jpg][sidemount.jpg]
First you must measure and drill the ply motor mounts out for
your motors, then attach them to the motor pylons with thick CA.
Once this is done, insert the mounts into the slots in the wing.
Carefully align the motor mounts laterally and vertically before
permanently attaching them to the wing. Build the jig using the
templates included in the instruction manual to ensure proper
mounting. Mounting the fuse to the wing aids in placement as well.
[wingmotor.jpg]
TAIL FEATHERS
The horizontal stabilizer is inserted into a slot cut out of the
fuselage. I called Ken Williams of K&A to ask his advice on how
to best cut cleanly through the fiberglass. Ken suggests heating
an exacto knife blade to make the cuts. I took Ken’s advice and
cutting through the fuse was like cutting through butter with
a hot knife. A couple layers of masking tape were used to keep
me from going “outside the lines”.
I also cut one opening larger than the other to allow adjustment
of the horizontal relative to the wing. The elevator is actuated
via an internal torque rod. The elevator halves are joined together
in the traditional method with a piece of wire bent into the shape
of a “U”. After the wire is bent, a piece of brass tubing drilled
and mashed at both ends is slid onto this wire and soldered into
place. The elevator control rod is then attached to the torque
rod providing a completely hidden and sleek elevator hook-up.
At this time you should install your elevator servo in the area
where the rear canopy is located, and also hook the servo to the
elevator control rod.
Rudder construction is equally straight forward. Simply install
the glue rail into the molded vertical, and then glue the rudder
to the rail. Sand the rudder to match the vertical, sand and install
the lower rudder balsa blocks and your done! I used some packing
tape over the fuse to protect it while sanding the rudder and
fairing blocks. By tack gluing the rudder, you can easily remove
it from the fuselage for ease of covering.
ABS PARTS
These molded parts are absolutely beautiful! They have panel lines
already formed into them, and were completely flawless. If you
have ever built nacelles from balsa you know that ABS nacelles
are a god send. All the parts have a slight indent running along
their perimeter that act as a cutting guide. I used a red fine-tip
pen to emphasize the marks, and then cut along the red lines.
I had all the parts trimmed and ready for installation in 30 minutes.
FINAL ASSEMBLY
Pull your motor and servo wires through the channels you cut into
the wing earlier and have them exit through the hole in the center
of the wing. Solder up your motors and attach them to the motor
mounts. Hinge and install the ailerons with your preferred method.
At this time also install your aileron and elevator servos.
You should now have the wing completed and covered in your preferred
method, the motors on the mounts, and the tail feathers covered
and installed. Bolt the wing to the fuselage and begin attaching
the ABS parts. I started with the cowls and nacelles. This is
a simple process, and measurements are provided in the instructions
to properly position the nacelles on the wing. Once you have them
where you want, wick thin CA into the joint between the wing and
the nacelle and your done. A glassed wing helps here as you get
a really strong bond. If you chose to film cover your wing, just
remove the film from the area where the nacelle will be attached.
The cowls are then slid onto the top and bottom nacelles. Instead
of holding the cowls on with screws, I chose to attach them to
the nacelles with small spots of RC-56 canopy glue. The cowls
aren’t load bearing, so they provide no real strength to the overall
structure. Using canopy glue sparingly also allows you to remove
them should you need to conduct maintenance on the motors.
The belly pan requires the creation of two balsa formers to keep
the belly pan from sagging. Use scrap balsa to raise the belly
pan to match the fore and aft sections of the wing saddle, attach
the balsa parts to the wing, and then attach the ABS belly pan.
I used a Dremel tool with a sanding drum to create the wing bolt
access holes. Your Dinah should be looking much like…….a Dinah
now!
Cut your canopies and mask them appropriately. I attached the
rear canopy permanently with foam friendly CA as it doesn’t “smoke”
the canopy when it cures. Formula 56 canopy glue also works well,
but I am not known for patience. The front canopy needs to be
removable for accessing the battery pack. I used rare earth magnets
at the front and back to hold the canopy down. These can be purchased
at your local Radio Shack.
Hook up your control rods to the ailerons and the elevator servo
to its control rod, and paint up your Dinah. A search on the Internet
produces multiple color schemes, but I chose to steal one from
the Ki-61 Tony. I used Model Masters acrylics and a final spray
of Model Masters Dull Cote. The red and white meatballs and other
decals were cut from sticky-back trim sheets. Install the speed
control, receiver, battery pack and your ready to head to the
field.
FLYING
I installed a bungee hook to my Dinah because I like being cautious
for the first flight. The benefit of a bungee launch is instant
airspeed and a straight ahead flight attitude. I arrived at the
field, set up the bungee launcher, and turned the controls over
to my good friend who is also an extremely experienced e-flyer.
We hooked the bungee to the Dinah, wiggled all the controls, and
then launched her into the air.
The Dinah pulled straight off the launch rail and began climbing
under power. The sound of those two motors pulling my new warbird
into the air was sheer enjoyment. Once in the air I took over
the controls and began making the standard circuits to get a feel
for the Dinah’s flight characteristics including gaining altitude
for power-off stall tests.
Stalls were straight ahead with the full amount of recommended
elevator applied. Releasing the elevator input and powering up
resulted in instant recovery. Very nice! Loops and rolls were
fantastic, wing-down low altitude passes really show off the lines
of this plane, and time spent on detailing really pays off here.
With the CP 1700 8 cell pack, I flew for 6 minutes before turning
into the landing pattern. Landings are a breeze with the Dinah.
Just point the plane into the runway, and it bleeds off speed
with a standard flair right before touch-down. The speed range
of the Dinah is amazing. Off the bungee the Dinah streaks along
at a good 65 mph, faster at full power in slight dives. However,
when its landing time, the plane slows down quite surprisingly,
and is very manageable. I left the field very happy with my Dinah’s
performance.
CONCLUSION
The Dinah has everything going for it. It is a unique subject,
it’s a warbird, a twin engine, and flies like a pussy cat. Anyone
who has flown an aileron plane can easily handle flying the Dinah.
Add to all of this the ease of building, fantastic quality of
the fuselage and ABS parts, and the friendly support from Ken
Williams himself just a phone call away. You simply cannot go
wrong buying a Dinah kit. I plan on buying another wing kit so
that I can install micro retracts and have the option of flying
at non-grass fields.
Wing Area: 304.5 sq in.
Weight: 40-45 oz.
Wing Loading: 19-21 oz/sq ft
Motor: 2 6vSpeed 400
Propeller: Graupner semi-scale 6.5x4
Speed Control: Great Planes Electrifly C-30 w/bec
Servos: 2 HS-55 (ailerons) and 1 CS-20 (elevator)
Receiver: Hitec 555 with case removed, Deans base loaded antennae
Battery: 8x1300CP; 8x1700CP
Manufacturer: K&A Models
Available From: www.kamodels.com
K&A Models Unlimited
All rights reserved.
Revised:
08/18/02