Randy Asplund's
Aviation Models
Yokosuka MXY7 Ohka (Cherry Blossom) and MXY7-K1 Ohka
Trainer
1/72 scale
The Ohka was essentially a flying
bomb with a pilot. This was the final operational phase of the
Japanese Kamikaze in the Second World War. It was small, just
under 20' in length, and was launched from the belly of a Mitsubishi
G4M2e "Betty" bomber. After being dropped, it would
glide the greater distance towards the target ship, and then the
pilot would ignite 3 rocket motors for less than ten seconds of
burn in order to make it a very fast moving target as it approached
the ships. Although several effective hits by Ohkas were scored,
a great number were shot down while still attached to their mother
planes because the bomber had to get fairly close to the defended
zone around the ships prior to launch.
The trainer version was a glider, and thus had no bomb
and no motors. The tail was fared over, and a landing skid was
attached beneath the fuselage. The model I built was based on
the example on display at the Wright Patterson AFB Museum in Dayton
Ohio. It was modified after looking at photos of the same type
taken at the end of the war.
The following is a look at how I built these two models.
The operational version was created from a test casting in resin
that a friend of mine made for his own use. I used it for measurements,
but it had a lot of problems. It was skewed, had big holes, and
the sections of the mold hadn't matched up. It required a lot
of work.
The first thing to do when building a model is to assemble
reference photos. These were captured on line and I shot many
of them myself from the actual aircraft on display in the museum.
This is just one page, but I have many other views.
I needed to have clear canopies, and I decided that
if I was going to do that, I might as well build the cockpits
and add pilots. I cut off the original canopy and then used it
to drop form a couple of new ones from very thin clear plastic
sheet. The wings were made of two sheets of plastic laminated
together and then sanded and filed until the proper airfoil shape
was achieved. More sheet to make the tail surfaces and to build
up the oval of the fuselage. I started with a wood dowel of a
diameter that matched the fuselage diameter of the original. I
used a dremel tool to dig out the cockpits.
After gluing on the wings and tail surfaces with super
glue, I started mounding up the bondo putty. Lots of carving ,
filing, and sanding followed. Then corrections with more putty.
I had to be sure to make the cockpit openings match the canopy
within reason because I would have to paint the inside and not
have putty color show at the seams when assembled.
It was a tight squeeze fitting the control panels,
pilots, & sticks into the cockpit, but I managed. The canopies
needed super glue to hold them down. I painted paper the same
color as the interior and then cut strips to make the canopy frames.
These were layered on with white glue, but would be better secured
later with clear gloss lacquer. Notice that the canopies go down
below where they would be looking at the final model. This is
because the frame bases are going to be filled over with putty.
You can see where I have painted the inside of the canopy plastic
gray up to the point where the fuselage will be built up.
Here is the final close up of the trainer version.
The skid had to be made from some very complicated pieces. These
were little 3 sides trapezoids on bases that attached to connecting
bars. They were hard to make on this scale, but the look was worth
it. I didn't do the best job, but considering how small the parts
were, I am not complaining. I also had to make control linkages,
air speed indicator, control surface balance weights, and finish
with the hoop skids that protect the wing tips. Not my best paint
job on the national emblem, but I will fix that later.remember,
this thing could fit in the palm of your hand.