This came in from Jim Spell. He sent us a detailed description of how he built and set up our Sniper, hope it is helpful!
J K Aerotech's Original Sniper Combat Glider
If you are a traditionalist when it
comes to building and flying airplanes, the Sniper Combat Glider will
definitely change your mind. If you have entered the world of "foamies"
but have been somewhat disappointed, the Sniper Combat Glider will
bring you back into the fold. And if you just want to have a wonderful
afternoon of worry-free flying...
The Original Sniper by J K Aerotech
is the perfect glider if you have any interest at all in entering the
exciting world of slope soaring. At twenty dollars it is a real bargain
and the returns on investment are measured in sheer joy and excitement.
It is well-designed and builds strong and resilient, providing a
perfect platform from which to begin your entry into slope and combat
soaring. With a little imagination it easily becomes a "looker" at the
flying field, eventually becoming your favorite little zoomer when you
just don't know what to "throw"
Building a foamie for the first time
is an exhilarating if not a somewhat perplexing experience.
Traditionally, a model put together this fast and easy and using
techniques better suited to "Mail Boxes are Us", may be presumed to be
unworthy of proper if not totally appropriate flight; but such is
simply not the case. Yes, it takes some getting use to, this foam
gouging and mailing tape covering process, but it is certainly not
difficult and the rewards are great.
The instructions for the Original
Sniper are, for the most part accurate. Follow them closely and with
good intent. There are, however, a few things to remember and these
come with an understanding of the building techniques employed and the
aerodynamic intent of the model itself.
First and foremost remember that when
you are cutting foam a dull X-Acto knife can mean hours of repair and
reconstruction. Use a new blade for ALL cuts of ailerons and elevators.
You can use the used blades for cutting and gouging the radio cavities,
but leave it at that. A 10 cent blade will save you hours of work. When
making the radio cavities, cut an accurate design and then gouge
accordingly. Foam will break off horizontally very easily, but it needs
to be cut in the vertical first or you risk loosing the shape of your
cavity. Remember to leave enough foam around your cavities so as to
utilize the natural strength and protection of the foam itself.
"Forward but not flimsy" is a good rule of thumb.
When "covering " the various parts of the model it is best to spray
3M-45 spray glue first to allow for tape adhesion, but allow the spray
to fully dry before beginning the taping process. An overnight wait
seems to be the best course of action for complete satisfaction.
Remember too, that mailing tape really doesn't stretch, (Editors
note: we do recommend stretching the tape as it is installed on the
wing only, as per our instructions. Doing so will strengthen the wing
by placing the wing under tension. However if you do not balance the
pull on the top and bottom, the wing will curve toward the tight side.
Do not stretch the tape when applying it to the fuse unless you wish to
change the wing/tail incidence.JKA)and
attempting to lengthen it while applying can lead to disaster. UNTIL
FOAM IS TAPED IT IS VERY BRITTLE. Tape firmly and evenly, but don't
think that you have a rubber band in your hand. An even and firm tape
application will be more than satisfactory.
As stated in the instructions,
leftover tape at the ends of wings and tail sections can be carefully
overlapped and will provide extra protection for those little
accidents. Additionally, overlapping will ensure a "sealed foil" which
will increase the strength dramatically, not to mention its water
A simple and economical glue for
assembly is "Liquid Nails". It is strong yet does not shatter on
impact. Just remember to cover, measure, and rehearse before attempting
any gluing process. Don't paint anything. Although it may look better,
it simply adds to weight and cover problems. Besides, there are great
colored tapes available. If you are intent on "customizing" your Sniper
you can add an old lightweight canopy up front to protect and cover the
radio gear, or put some decals on the wings. As with all slopers,
contrasting wings no matter how it is achieved, is a good idea;
especially when its upside down and backwards.
To get the optimum
performance envelope out of your Sniper it is important to understand
the aerodynamic intent of the model and not try to defeat this either
knowingly or unknowingly. The wing span of the Sniper is 42 in. and its
over all length is 33 in. With a long and relatively thick chord
length, a razor sharp leading edge, and a short "swing weight" (the
distance between the CG and the tail sometimes referred to as
"moment"), the CG, or Center of Gravity, becomes paramount. Its proper
location marks the difference between a kite like floater and an
efficient penetrating combat sloper and this difference can be less
than 1/32nd of an inch. Its overall lightweight adds to this
potentially lengthy "set up" of the Sniper. Calculating the distance
from the leading edge to the CG is based on wing cord, its shape and
thickness, and the subsequent aerodynamics that result. It is critical
to overall satisfaction that the CG be placed at 3 and 6/32 inches from
the leading edge and as stated, changes of a 32nd of an inch can have a
profound effect on the penetrating ability of the glider. 3 and 6/32
inches is at least a beginning point that allows for the appropriate
analysis of the Sniper's flight characteristics and the subsequent
changes you may want to make. Again, it is the Snipers design that
makes the CG placement tricky, yet of primary importance. Its razor
sharp leading edge means that when the Sniper is in the air, the glider
is either lifting, dragging, or penetrating efficiently with no
turbulent room for error. A more rounded leading edge would allow a
more forgiving CG point but would greatly sacrifice the model's precise
control and exact maneuvering capabilities. Its light weight and short
"swing weight" further exacerbates this process, but in the end the
flying characteristics more than makes up for time lost to "trimming".
To its credit, once this critical point has been achieved, the Sniper
becomes a model that flies as if it were on "rails" in all types of
wind. Finally, if you simply can't get the Sniper to penetrate to your
satisfaction, simply add ballast at the approximate CG point, carefully
drilling a hole into the bottom and adding weight. Make sure the weight
cannot shift and then tape over the hole. This technique also serves
well on "extreme" days when others are afraid to fly.(editors
note: we adjusted blast at the slope site and 3 to 4 oz taped to the
underside made the Sniper a rocket in 30+ mph winds.JKA)
Study the application of moveable
surfaces on the Sniper. This technique, described in the instructions
is invaluable and can serve you well on other gliders in your
collection. One important note when it comes to control surfaces is in
dealing with the installation of the control horns. Gluing them on as
well as screwing them in will make for a stronger connection and the
disturbing tendency of bent, crushed, and otherwise distorted control
surfaces will be lessened.
Although the Sniper is relatively
quick and easy to build, do not underestimate the flying capabilities
of this superb model. Given the proper CG to allow for effective
penetration, the glider becomes a very responsive and yet stable flyer.
By "dialing in" the proper throw deflections for the ailerons and
elevator and even adding a computer radio with micro servos for
flaperons and precise adjustments, you can maneuver with the best of
them. The sky, the wind, and your imagination are its only limits.
What makes the Sniper truly special
however, is that when you fly it your learning curve jumps off the
page. After a few flights you lose the fear of crashing that comes with
building and flying a Sagitta 6OO or any other time intensive stick
built model, and you just fly, free from worry and free from
consequence. This, along with the incredible amount of time you can now
spend perfecting that roll or hammerhead stall you have always been
reluctant to try, makes the Sniper Combat Glider by J K Aerotech a
truly indispensable addition to your airplane collection.
Jim Spell, Vail Fire Department, 42 W. Meadow Dr., Vail, CO. 81657