09-08-2012, 03:03 PM
Aerobatics
Aerobatics-Beyond_straight_and_level.pdf (Size: 1.4 MB / Downloads: 117)
Why is IMAC so hot?
NO MATT
E R
WHICH
way you
turn, manufacturers
seem to be
churning out
IMAC-style airplanes,
engines
and accessories at
a phenomenal
rate. With the
onslaught of
CAPs, Giles and Extras, the scale aerobatic enthusiast
has at last found utopia. But is this hot trend
in the modeling industry based on the airplanes,
the thrill of competition, or both?
IMAC has been around for over 24 years, and
its original intent and premise have managed to
remain fundamentally intact for nearly a quarter
of a century because of their simplicity. IMAC’s
goal is simple: “To duplicate full-scale aerobatics
with RC aircraft in a realistic manner that is challenging
for the contestants as well as interesting
for the spectators.”
Tournament of Champions. Though it’s unlikely
that the average modeler will have the funds and
support vehicle to sustain a 40-percent Extra, the
28- to 35-percent market perfectly fills the niche
of size versus cost. Most kits in this range are not
that expensive and don’t require a semi-trailer to
get to the field. There is also the age-old premise
that “bigger flies better”; this has been debated
by pilots and judges for years.
My contention is that you can win with any
aircraft, big or small, as long as you practice. I
proved that point by winning the 1997 Advanced
NW Regional Championship with my YS
1.20NC-powered Extra 260. I flew against nothing
smaller than a 30-percent Laser all year, but
still came out on top. I do believe that bigger
probably “presents” slightly better, but it’s certainly
not like night and day; more like dusk
versus dawn … take your pick.
Straight and level flight
You should practice
straight and
level as much as
you do any other
maneuver. It is also
where new precis
i o n - a e r o b a t i c s
pilots should begin.
It may seem like
the most boring
thing to do, but in
reality, straight and
level flight is one of
the most difficult
maneuvers to master. Sure, rolling circles, tail
slides and multiple snaps each have their own
levels of difficulty, but think about what comes
before and after each one of these: straight and
level flight. One of the most difficult things to do
after performing a rolling circle or a snap is to
retain the same flight path.
Cross-box maneuvers
Cross-box maneuvers are designed to
allow an aerobatic aircraft to travel perpendicular
to the original flight path to
correct for wind drift during competition.
These maneuvers are essential in full-scale
International Aerobatic Club (IAC) competition,
since the pilots do not use wind correction as we
do in IMAC competition. Since IMAC rules permit
wind correction, there is arguably no reason
to use cross-box maneuvers. IMAC does, however,
allow these maneuvers because we try to
emulate full-scale competition, and it also gives
the pilot a chance to use the entire aerobatic box
to fly his sequence. Most competition maneuvers
can be converted to cross-box maneuvers by executing
a 1⁄4 or 3⁄4 roll during the up- or down-line
portion of the maneuver. For example, take the
hammerhead; a standard hammerhead flown at
the end of the box can be flown as shown in
Figure 1. Now add a 1⁄4 roll in the down line, and
the model will exit perpendicular to the flight
path (see Figure 2).
The same can be said for a simple “Humpty
Bump.” Adding the 1⁄4 roll on the way up (up line)
can allow you to adjust the diameter of the top
radius while flying in the cross-box direction.
The 1⁄4 roll on the way down allows you to exit
parallel to the initial flight path but slightly farther
in or out (see Figure 3).