MK
"Extra 300LS " Build Report by Derek Chan
Introduction
MK
Models from Japan are renowned
for producing the best in balsa
kits. The Extra 300LS, designed
by Quique Somezni and his dad, is
no different. The model reviewed here is the .140 version, though a
.90 size is available too. My dad obtained the Extra from Singapore
Hobby Supplies, which stocks an excellent range of MK parts, among
other Japanese goodies. The kit was packaged in a relatively small box,
considering it is a 2+2 model, unlike the huge boxes from ZN Line. Upon
inspection, one will be amazed at the quality of the kit. All wood pieces
were beautifully cut, and 1:1 scale drawings were provided for the wing
and fuselage. A packet consisting of goodies was also included, comprising
of the following MK parts: Aluminum Horns for all surfaces, Spinner,
Fuel Tank, Retracts, 'Magic Box', Tail Wheel and the Bell-Crank system.
A beautiful joined one piece front and rear 'turtle decks' were also
supplied. In short, all relevant hardware needed was provided. No instruction
manual is provided as one is expected to be quite
a proficient builder before attempting this kit.
Little instructions and diagrams are provided on the plans, but text
is in Japanese.
Fuselage
We
agreed beforehand that the cost of construction should be kept down
for the Extra 300LS,
like using a refurbished YS 140FZ, instead of buying a new(and better)
YS 140 Ltd, etc. Can
anyone sponsor the site?? Before
my dad(Patrick Chan), who is the builder, sponsor and my caller, started
on the model, we decided on one main change to the kit. We decided against
the use of retracts, to the in-vogue fixed-gear setup. Fixed-gear planes
are increasingly popular among F3A planes and obtained the Bolly
F3A Carbon fixed-gear from Singapore
Hobby Supplies. It will
be our first pattern model with a fixed-gear setup. It was mounted on
the fuselage, behind the bulkhead area, like most
planes with a fixed-gear setup.
The kit supplied a balsa sheet, and strengthening was carried out. I
laminated it with carbon fiber, and reinforced with plywood beneath.
There is a nice grove on the wheel pants, meant for the carbon gear.
Nice touch.
The rest of the fuselage construction was quite straight forward buildup.
Only change being the decision to use twin elevator servos, rather than
the recommended one(with the MK Bell Crank). There has been many debates
over the effectiveness, but we decided to try it out. Another minor
change was to convert half of the tail post to become part of the rudder.
Undercowl was provided in the form of a very large fiberglass piece,
and MK 'Magic Box' to secure it to the body. Working with such a large
piece, installation proved fiddly at times. The
standard MK Soft Mount was used the YS 140 FZ, vibration is less than
the 140 Ltd.
Wing & Stabilizer
Unlike normal construction, where 2 halves are joined together, the
wing is made of 3 major sections. This process involves many ribs, a
perfectly flat table, and patience. We begin to see the benefit of foam
core wings... The joints need to be strong, though beneath lies a box-like
structure spar. One
fellow modeller's Extra 300LS wing folded, and this made us wary of
the join. The present schedules exert lots of forces on the wings, and
extra care was taken. Composite laminates were used across the joints,
and likewise on the stab.
Flight Performance
With a YS 140FZ, fitted with a APC 15x12, this proved to be just sufficient
to pull the wide-bodied Extra. We reckon the 140Ltd would be
much better. The wide body Extra 300LS has sense of floating
around the sky, rather than sitting in the air. It, however, presents
well in flight. Due to the thin wing profile, downlines are still relatively
fast. One would have thought the wide body would provide much drag.
Snaps are manageable, but lack crispness. Knife Edge tracking is very
good, with only a very slight pitch. The fixed gear setup allowed us
to save some weight, and with my dad's building, it weighed 4.5kg, lighter
than the recommended 4.8kg> We have seen Extra's that weighed in
at 4.99kg!!! It also adds to a semi-scale effect, and looks impressive
on the ground as in the air.
Overall
The fixed gear setup is definitely worth the extra effort(I understand
MK has a similar option available). This balsa kit is similar to all
MK offerings, excellent quality. However, one has to ensure that everything
is straight, since all parts are buildup. Everything fits together well,
much like a big puzzle. A slight offset, would mean a poorer flight
performance. When one has to consider the price versus performance,
one has to choose closely among other Pattern offerings by European
makers, like ZN
Line
or PL Prod.
Overall, a decent pattern plane, away from the normal composite models.
Whether it is a better kit, we will leave it up to you. - Derek
Chan
