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Introduction
The SIG SOMETHIN EXTRA was conceived as an all out fun fly design that does not necessarily look like one. Sure, it has the
large, thick symmetrical wings along with generous area and large flight control surfaces, normally associated with fun fly type
models but when the whole thing is put together, it s really a great looking airplane! We also wanted this model to be as much
fun to build as it was to fly, so we decided early on in the project to produce all of the parts with our laser cutting system, to
assure absolute accuracy throughout the building process. The result is that the SOMETHIN EXTRA builds so fast and so
accurately, it is almost in a class by itself. The design is totally unique for this type of model in that the wing panels are separate
and removable, using an aluminum tube joiner directly through the fuselage. This set-up has a lot of benefits, such as being
able to locate the wing panels directly on the thrust line and having virtually the entire fuselage, forward of the trailing edge,
available for radio installation and access. Of course, transportation and storage of the finished model also becomes easy and
convenient.
The flight characteristics of the SOMETHIN EXTRA are nothing short of incredible. It is fully capable of ultra short field take-offs
and landings and almost anything in between. An astounding roll rate, knife edge flight to the next county, instant spin entry and
exit, tight inside and outside loops and superb low speed handling are just the beginning! This design has outstanding ground
handling characteristics and can be flown in considerable wind conditions. We can t think of a better club contest airplane than
the SOMETHIN EXTRA! While this design can certainly be flown with a normal 4-channel radio and five servos, it really gets fun
when you use one of today's simple programmable computer radio systems. These radios allow you to mix surfaces, employ
flaperons and fine tune and maximize the performance of this model to create an airplane that is nothing short of spectacular in
the air. We would also advise you that this is definitely an airplane that benefits from the use of a radio system with dual rates
on both the ailerons and elevators. When the model is set-up as suggested in these instructions, you will have an airplane that
simply does it all! If you have been looking for a design that is fully up to your flying skills, then the SIG SOMETHIN EXTRA was
designed and engineered just for you.
The SOMETHIN EXTRA kit has been very carefully engineered to provide you with an enjoyable building experience. The plans
were developed using our powerful CAD (Computer Aided Design) system. To insure absolute accuracy, the individual parts
themselves were then generated using these same plans through a path directly to our computerized laser cutting system. This
methodology produces incredible accuracy, minimizing and/or eliminating the need to prepare parts prior to assembly. When
the above system is used in concert with SIG s legendary quality balsa and plywood, the result is a kit that has only been
dreamed of until now.
Your SOMETHIN EXTRA kit is very complete. We have included almost all of the hardware that is required along with a very
high quality custom made landing gear and wheel pants to match. However, there are still a few items that you will need to
complete this kit. Some of these are:
4-Channel Radio System w/ 5 Servos
Spinner: 2-1/4 Dia.
6 Aileron Servo Lead Extension - 2 required
Wheels: Two 2-3/4 Dia. Mains, One 1 Dia. Tailwheel
Engine: .40 - .46 2-Stroke or .56 - .65 4-Stroke
Glue: Thick or Medium and Thin CA and 5-Minute Epoxy
Paint: Engine Compartment and Wheelpants
Propeller
Covering Material: 2 - 3 Rolls (See Covering Section)
Fuel Tank: 8 Ounce
Engines, Propellers And Mufflers
We have flown our prototypes using two-stroke .40 size engines with excellent results. Our engines were bearing equipped, not
the plain bearing type. Plain bearing (or bushed ) engines will likely fly the model adequately but will probably not have the top
end power for extreme vertical maneuvers. Understand that the SOMETHIN EXTRA was not designed to be a fast airplane but
rather a highly aerobatic model. It therefore flies best when equipped with a strong .40 to .46 (even .50 class) engine with
bearings. Throttle management through various maneuvers is of course suggested and will result in smoother flight and a lot
more fun.
Four-stroke engines will also fly this design. However, by the nature of their construction, they are always heavier for any given
displacement. Since it is essential that the airplane balances at the point shown on the plans, using a four-stroke engine may
require additional weight and balance considerations to achieve the correct center of balance (or CG).
When using two-stroke engines, avoid heavily pitched props. Ideally, you want your engine pulling as well vertically as it does in
horizontal flight. To do this it needs to run at or about its best rpm level to take advantage of its power curve.
Always use an effective muffler! A loud engine could cost you (and possibly your club) the use of
your flying site if it offends nearby non-modeling neighbors. Use the muffler that came with your
engine or an after-market muffler made especially to quiet two-stroke engines.