1) PITCH TRIM ( elevator function)
The pitch trim is seldom an issue if the proper radio gear is installed, the battery pack positioned
properly, and the CG range is correct. The included ball link elevator pushrod is factory set to
mechanically position the tail within limits that are trimmable with the radio transmitter trim tabs.
The pushrod is threaded nonetheless so the length of the pushrod can still be adjusted if
needed.
2) YAW AND ROLL TRIM: (rudder function)
The Slow Hawk 2 wingsail is manufactured with great care to ensure a symmetry between the
left and right wings. Even so, various factors in the flexible wing design may lead to a tendency
for the model to pull to the right or to the left during flight. Some of these factors may include a
subtle but inherent difference in left/right carbon wing spar stiffness, or a slight inherent bias in
the wingsail fabric. Most people report little if any trim adjustments needed in their model and
small trim adjustments can simply be made with the transmitter trim tab on the rudder stick.
However, if you find that your model pulls to the right or to the left in flight to a degree that it is
awkward and perhaps even annoying, there are some adjustments that can be made to correct
the problem. A properly trimmed model is also a more efficient flyer so trimming the model
properly is recommended if needed.
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First a little ornithopter theory
which willl make more sense out of the wing trimming
adjustments plus since you bought this kit you are probably of the mindset that wants to know a
little about how the machine flies.
The debut of the commercially available RC ornithopter by Sean Kinkade as a successful flying
machine was a result of side-stepping much of natures complexity and replacing it with a bare
minimum of requirements to facilitate a machine that looks and flies similar to a bird. The
membrane wing on Kinkade ornithopters is more like a hybird of a bird wing and an insect wing,
since it has an unjointed main spar. One FAQ heard by us over the years is "how can the
ornithopter fly when the wing pushes up just much air as it pushes down since it has no joint to
spill the air like a live bird". What this question doesn't take into account is thrust, and
subsequent airspeed which generates lift due to the angle of attack of the wing just as with a
fixed wing airplane. So although there ARE some curious aerodynamics at work in a flexible
flapping wing, which you will most likely observe during the course of flying the model, the wing
basically consists of an inner lifting section and an outer thrusting section separated by a
diagonal batten. This batten however is flexible and allows lift and thust to be shared by both
sections along the wing.
The ornithopter derives most of its thrust from the outer portion of the wing membrane. The
thrust is coming off the wingtips in a semi-circle relative to the fuselage axis and the wings are
in essence oscillating linear propellers. The thrust is coming off both the left and right wings and
any difference in thust between the two wings will result in a turning tendency. One way to look
at it is similar to a twin engine plane so to speak. Due to the mechanical advantage of the
thrust against the wing spars which are of course attached to the fuselage, any imbalance of
the wing thrust will easily overcome or fight against any other forces that might counter these
forces such as the tail angle or weight shift of the battery, etc. So, what a trim problem
usually
boils down to is a thrust imbalance of the wings which can be corrected in several ways. Below
