The outer aileron servo is accessed with a hatch. Inner servos are
accessed from the wing center in a similar fashion as the horizontal
The engine installation. Grommets on spark plug wires prevent chaffing on
the shield and fiberglass. The smoke pump is installed on the bottom of
the engine dome.
each fuselage. The custom fit is great, but it means that each
aircraft is slightly different and that no template for engine
centering is possible.
The best way to solve this dilemma is to secure the
fuselage vertically. Place the engine on the dome and mount
the cowl. Place the spinner backplate on the engine then
move the engine into the proper position so that the spinner
matches the cowl. Carefully remove the cowl and mark the
engine mounting-hole locations. It sounds cumbersome, but
it results in a perfect fit. Aluminum spacers, 1/4 x 20 bolts,
and blind nuts hold the engine securely in place.
The throttle servo is located inside the dome with straight-line geometry to the throttle arm on the carburetor. The
smoke pump is mounted on the outside of the dome on the
The ignition module is mounted on a plywood plate with a
combination of hook-and-loop fasteners and a hook-and-loop
strap. This assembly is attached to the top inside of the dome.
Rubber grommets on the top of the dome provide shock
absorption for the module. Large grommets are used again on
the side of the dome to allow the spark plug wires to exit the
fuselage without abrading the fiberglass or shield.
Rudder servos are ganged in line on the premolded servo
tray—double check to make sure there is sufficient adhesive
attaching the rudder servo tray. It is extremely important to
adjust all servo throws so that there is matched throw in all
directions. The same goes for the ailerons. We used multiple
Hanger 9 amp meters to match the servos on each control
The receiver and satellites are mounted with foam tape in
multiple directions throughout the fuselage. The removable
tank floor contains molded areas for both a fuel and smoke
tank. Again, double check to make sure there is sufficient
adhesive on the tank floor mounts.
To keep the airframe as clean as possible, Jeti magnetic
switches were used for the ignition and radio system. A
Because all of the electronics were used during the
previous flying season, the difference can only be attributed
to the airframe. This is probably because of the rigid
construction (no flexing of the wings and the control
Chris explained that “control authority is maintained
regardless of airspeed. Maneuvers are repeatable. Regardless
of attitude or airspeed, the Krill Extra 330 does not hunt or
drift.” All of this was accomplished without an onboard gyro.
Let’s go through some maneuvers. The takeoff was solid
with no tendency to veer off center, even with a direct
crosswind. Climbout revealed the need for a little elevator
trim. Loops tracked well, and rudder correction for crosswind
was predictable and consistent throughout the varying
airspeed of the loop.
Knife-edge flight required just a touch of down-elevator.
Four-point rolls were crisp with clear stops at each quarter,
probably because the composite ailerons did not flex.
Vertical lines showed the need for a little more right thrust,
which was accomplished with a 1.5mm washer under the
left-side engine mounts. Inverted flight required a touch of
down-elevator, as expected.
Stalls were straightforward with no tendency to fall off or
snap. Spin entries were again solid, with a tendency to fall off
until controls are given. Landing is as predictable as the rest
of the flight—solid and in control through to touchdown.
This is a very clean airframe that carries energy for a long
time, so plan your pattern accordingly. The center of gravity
is set 1/4 inch in front of the trailing edge of the aileron
KE 3 Model Aviation JUNE 2015 www.ModelAviation.com