BALANCE
Balancing your airplane may be the single most important step in
preparing it for flight. All airplanes, model or full-size, must be ac-
curately balanced in order to fly successfully. An airplane that is
not properly balanced will be unstable and will most likely crash.
NOT ALL SOMETHIN’ XTRAS WILL BALANCE THE SAME
It is impossible to produce a model airplane kit that will automat-
ically have the correct balance point. Not everyone uses the same
motor or radio gear - and all those items can vary in weight! Even
propellers of the same size can vary as much as a 3/4 oz. be-
tween different brands. That’s why every model must be balanced
before flying. Don’t feel that whatever the balance point your
model came out at is “good enough”. Check carefully and make
whatever adjustments are required. Trying to fly an out of balance
model is dangerous!
Preliminary: All the parts and components that will be in the air-
plane in flight must be installed in their correct positions. This in-
cludes all the radio gear, the propeller, battery pack, etc. Every
piece of essential equipment must be installed, ready for flight.
ACCEPTABLE BALANCE RANGE FOR SOMETHIN’ XTRA
is from 3-5/8" to 4-5/8"
AFT OF THE LEADING EDGE OF THE WING
The following table lists several acceptable measurements and
the equivalent percent of MAC (Mean Aerodynamic Chord).
DISTANCE
% MAC
3-5/8" = 26%
3-15/16" = 28%
4-1/4" = 30%
4-5/8" = 33%
A balance point approximately 3-1/2” aft of the leading edge is
good for initial test flights. After test flying you can adjust the bal-
ance point to fit your flying style.
CONTROL SURFACE TRAVEL
The following control surface data has been flight tested with the
Somethin’ Xtra. However these numbers are only recommended
as a starting point. Your flying style may dictate changes.
When it comes to test flying a new model, we always advise mod-
elers to choose a calm day with little or no wind. These conditions
allow you to better evaluate and more accurately adjust the trim
requirements of your airplane.
Always make it part of your pre-flight routine to check each control
on the airplane, making sure the surfaces are moving in the cor-
rect directions. Also check each control linkage to be sure they
are secure and that nothing is loose. With all the controls
checked, make a range check with your radio system, making
sure everything is working perfectly.
The Somethin' Xtra is most certainly not a beginner's model. It
was designed as an all-out aerobatic aircraft with all of the inher-
ent attributes of those types of airplanes. If this is your first aero-
batic model and you have relatively little actual air time, we would
urge you to seek the assistance of a qualified R/C pilot to help
you through the first few test flights. Keep the ailerons and eleva-
tors in their low rates. Once airborne, get to a reasonable altitude
before inputting any trim changes. Once the model is trimmed for
straight and level flight, begin getting the feel for the way it flies.
We hope that your Somethin' Xtra will provide you with many en-
joyable hours of flight. Good luck and safe flying!
FLYING
16
WARNING! THIS IS NOT A TOY!
Flying machines of any form, either model-size or full-size, are not toys!
Because of the speeds that airplanes must achieve in order to fly, they
are capable of causing serious bodily harm and property damage if they
crash.
IT IS YOUR RESPONSIBILITY AND YOURS ALONE
to assemble
this model airplane correctly according to the plans and instructions, to
ground test the finished model before each flight to make sure it is com-
pletely airworthy, and to always fly your model in a safe location and in a
safe manner. The first test flights should only be made by an experienced
R/C flyer, familiar with high performance R/C aircraft.
JOIN THE AMA
The governing body for radio-control model airplanes in the United States
is the ACADEMY OF MODEL AERONAUTICS, commonly called the
AMA. The AMA SAFETY CODE provides guidelines for the safe opera-
tion of R/C model airplanes. While AMA membership is not necessarily
mandatory, it is required by most R/C flying clubs in the U.S. and provides
you with important liability insurance in case your R/C model should ever
cause serious property damage or personal injury to someone else.
ACADEMY OF MODEL AERONAUTICS
5161 East Memorial Drive
Muncie, IN 47302
Telephone: (765) 287-1256
AMA WEB SITE: www.model aircraft.org
CUSTOMER SERVICE
SIG MFG. CO., INC. is committed to your success in both assembling
and flying the
Somethin’ Xtra
. Should you encounter any problem build-
ing this kit or discover any missing or damaged parts, please feel free to
contact us by mail or telephone.
SIG MFG. CO., INC.
P.O. Box 520
401 South Front Street
Montezuma, IA 50171-0520
PHONE: 1-641-623-5154
FAX: 1-641-623-3922
SIG WEB SITE: www.sigmfg.com
SIG E-MAIL: [email protected]
LIMIT OF LIABILITY
The craftsmanship, attention to detail and actions of the builder/flyer of
this model airplane kit will ultimately determine the airworthiness, flight
performance, and safety of the finished model. SIG MFG. CO.’s obligation
shall be to replace those parts of the kit proven to be defective or missing.
The user shall determine the suitability of the product for his or her
intended use and shall assume all risk and liability in connection therewith.
LOW RATE
HIGH RATE
Elevator
1" up
1-1/2" up
1" down
1-1/2" down
Ailerons
7/8" up
1-3/8" up
7/8" down
1-3/8" down
Rudder
1-5/8" right
2" right
1-5/8" left
2" left
PRE-FLIGHT