Precision Aerobatics Katana MD Build Notes

The Katana MD is especially good looking in red.

Continuing in our Builds Notes series, this is my experience assembling the Precision Aerobatics Katana MD. This 46" wingspan acrobat is a premium-quality ARF, with a substantial amount of work done at the factory, and a unique carbon fiber reinforced balsa and plywood design.

Rather than writing full reviews, these Build Notes articles focus on the build steps, kit quality, and workarounds for common problems you might encounter.

Pluses:

The ailerons are the best of any ARF I’ve built. They are not only hinged at the factory, but rotate in a pocket such that there’s no gap.
The canopy is magnetic and factory-assembled, no work to be done at all.
The build quality is very good. Both the internal structure and the covering were well done.
The instructions provide a good amount of detail, but the photos are too small, and black and white.
The motor box is pre-drilled for the Thrust 30 motor, which just barely squeezes in from the bottom, but otherwise installs easily.

The cowl is very attractive, but it’s a shame it’s not magnetic.

This is how the ailerons come from the factory – very nice.

The magnetic, one-piece canopy. Looks great and makes changing batteries easier.

Minuses:

The wheels didn’t fit on the axles. I had to ream them out to double the size of the opening.
The main landing gear hardware was different than in the manual, and it used large washers which hit the curve in the gear and didn’t sit flat.
The pull-pull hardware did not have enough threads on it, so that it would not clamp down on the carbon fiber servo horn. I had to add some washers.
The aileron and elevator linkages are just too much work and not adjustable when finished. They require wrapping a z-bend with thread and using CA to glue it to a carbon rod, and then using heat shrink tubing to strengthen it.
Fitting the cowl was a hassle and the screws don’t look very good. At this price I’d like to see a magnetic cowl, completed at the factory, that just snaps on like the canopy with zero work.
I installed both nylon wing bolts as described in the manual, seating the heads completely flat, but when attaching the wings, both bolts were off by 1/8 inch. I had to bend them significantly to slide the wings on.
The factory made light cuts for the control surface hinges, but they were up to 1/2" off between the control surface and the matching stabilizer. They should be cut correctly or not at all.
The rudder and elevator are supposed to be sealed with clear heat shrink, which is not only tedious, but many ARF builders don’t own an iron.
The battery tray may not be tall enough for a 3S LiPo which has spacers between the cells. Plan on using thinner packs.
The carbon fiber stickers on the fuse were peeling up in a number of places.

Notice the washers added on the pull-pull arm.

The black stickers were peeling up in a few places.

Thicker 3S LiPo packs are hard to install and may not fit at all.

Tips:

Replace the aileron and elevator linkages with threaded rod and clevises. These weigh only 2.6 grams each, compared to about 1 gram for the stock hardware, but are much easier to set up.
Insert a wing half on the carbon spar before gluing the nylon wing bolt. Bring the wing close to the fuselage, so that the wing bolt can be aligned with its hole, before applying CA.
Use self-adhesive clear covering to seal the rudder and elevator hinge gaps.
Be careful when using a 2.4 GHz receiver in the Katana, due to possible carbon fiber interference. Make sure to use a full range receiver with at least two antennas, pointed at 90 degrees to each other.
The instructions suggest CA for attaching the stabilizers. I recommend using epoxy for a stronger bond.
Make sure that the lowest rudder hinge will not interfere with the pull-pull control horn.
Check that the servo extension to the elevator servo does not interfere with the pull-pull cables for the rudder.