| General
Comments
This is a list of
areobatic figures that have common names. Some of
these were invented during aerial combat in WW I.
I have included a short verbal description and the
IAC symbol for each basic figure.
The symbols for the
figures follow the rules of the FAI for depicting
aerobatic figures. The figure starts at the small
solid circle and ends at the vertical bar. All aerobatics
figures start and end from horizontal lines in either
upright or inverted flight. In aerobatics competition,
most figures can be entered and/or exited from either
upright or inverted flight. This affects the difficulty
numbers for the figures. In general, the altitude
at which the figure is entered does not have to be
the same as the exit altitude. Exceptions are for
instance the Cuban Eight, all full loops (regular
loop, square loop, etc). In cases where the entry
and exit lines have to be the same altitude, they
are drawn slightly separated to better show them.
The elements used
in these figures are horizontal, vertical and 45 degree
lines. These describe straight flight in these directions.
Solid lines describe upright flight, dashed lines
describe inverted flight. Parts of loops connect these
line segments (see e.g. the Humpry-Bump). Rolls in
1/4, 1/2, 3/4, etc increments up to 2 rolls can be
added to the lines.
The looping portions
in almost all figures have to have the same radius
in all parts of a figure. For instance the quarter
loops going into and coming out of a hammerhead have
to have the same radius. There are some figures where
this does not apply completely.
Rolls on vertical
lines and on 45 degree lines have to be centered on
this line to score well. Any deviation from the center
results in a downgrading during a competition.
Rolls
Rolls can be added
to most other figures to increase the difficulty factor
of the figure. There are two basic types of rolls:
slow rolls and snap rolls (flick rolls in european
parlance).
Slow Rolls
1.) 2.)
Slow rolls have to
be flown normally on a straight line (exception is
the avalanche). The roll rate has to be constant and
the longitudinal axis of the plane has to go straight.
This requires constantly changing rudder and elevator
control inputs throughout the roll. Hesitation or
point rolls include stops at certain roll angles.
The number on the base of the roll symbol describes
the number of points the roll would have if it were
a 360 degree roll. Allowed are 2 point, 4 point and
8 point rolls. The fraction on the arrow of the roll
symbol describes what fraction of a full roll is to
be executed. If no points are specified, rolling is
done without hesitations. If no fraction is specified,
a roll symbol that starts at the line specifies a
half roll (see description of the Immelman). A roll
symbol that crosses the line specifies a full roll
(first figure). The second figure shows the symbol
for 2 points of a 4 point roll (adding up to half
a roll) from upright to inverted flight.
Snap Rolls
3.) 4.)
Snap or flick rolls
also have to be flown normally on a straight line.
A snap roll is similar to a horizontal spin. It is
an autorotation with one wing stalled. Figure 3 shows
the symbol for a regular snap roll, figure 4 for an
outside snap. In the regular snap, the plane has to
be stalled by applying positive g forces. In an outside
snap, the plane is stalled by applying negative g.
In both cases rudder is then used to start autorotation
just like in a spin.
Loop
This is one of the
most basic maneuvers, but not easy to fly well. It
has to be perfectly round, entry and exit have to
be at the same altitude. The difficulty in flying
this manuever well is in correcting for effects of
wind drift. In competition, it helps if you don't
have to fly first, so you can watch what your competitors
are doing and judge the wind drift that you have to
take into account.
The maneuver starts
with a pullup of about 3 - 4 g. Once past the vertical,
the back pressure on the elevator is slowly relaxed
to float over to top of the loop to keep it round.
Past the top, the back pressure is slowly increased
again throughout the back part till horizontal flight.
The plane has to stay in one plane with the wings
orthogonal to the flight path. Rudder is used to maintain
the plane of the figure and ailerons are used to maintain
the orientation of the wings.
Avalanche
This is the basic
loop with a roll (usually a snap roll) at the top
of the loop. The roll has to be centered at the top
of the loop.
Square Loop
This is a variation
of the basic loop. The two vertical lines and the
horizontal line on top have to be of the same length.
The exit line at the bottom has to be at least as
long as the other three sides. The quarter loops that
connect the four sides have to have the same radius
at each corner.
Eight Sided Loop
This is another variation
of the basic loop. The two vertical lines, the 45
degree lines and the horizontal line on top all have
to be of the same length. The exit line at the bottom
has to be at least as long as the other seven sides.
The eigth loops that connect the eight sides have
to have the same radius at each corner.
Immelman
The figure starts
with a half loop to inverted flight. A half roll then
results in horizontal upright flight.
This is one of the maneuvers that have been used in
WW I to reverse direction. This maneuver does not
preserve speed and altitude. It trades speed for altitude.
Split-S
The figure starts
with a half roll to inverted followed by the second
half of a loop downward.
This is another maneuver
to reverse direction. This one, like the immelman,
does not preserve speed and altitude. In this case
it trades altitude for speed.
Half Cuban Eight
Five-eighths of a
loop to a down-line at a 45 degree angle. The plane
is inverted at this point. Centered on this downline
is a half roll from inverted to upright. A pullout
to horizontal completes the figure.
This is another one
of the maneuvers that reverse direction. The downline
can be used to adjust the altitude and speed at the
end of the figure.
Cuban Eight
Two Half Cuban Eights
can be combined to form a Cuban Eight or Lay-down
Eight. In this figure in competition the two looping
parts have to be flown at the same altitude with the
same radius. The exit has to be at the same altitude
as the entrance to the figure.
Reverse Half Cuban Eight
This figure starts
with a pull to a 45 degree up-line. Centered on this
line is a half roll from upright to inverted. Five-eighths
of a loop complete the figure to horizontal flight.
This again is one
of the maneuvers that have been used to reverse direction
while preserving altitude and airspeed.
Reverse Cuban Eight
Like the Cuban Eight,
a Reverse Cuban Eight can be formed by flying two
Reverse Half Cuban Eights back to back.
Inside-Outside Eight
This figure is similar
to a Full Cuban Eight, but it does not contain any
rolls. The second loop is an outside loop. Again,
the two loops have to have the same radius and have
to be flown at the same altitude. Entry and exit have
to be at the same altitude.
Hammerhead
A quarter loop into
a vertical climb. When the plane stops climbing, it
pivots around its vertical axis (which is now horizontal).The
nose moves in a vertical circle from pointing up through
the horizon to pointing down. After moving vertically
down to pick up speed again, the maneuver is finished
with the last quarter of a loop to horizontal flight.
This figure can have optionally rolls on both the
up-line and the down-line.
The quarter loop is
flown just like the first part of a loop. When the
plane is vertical, the elevator backpressure is released
completely. During the vertical line up, some right
aileron and right rudder is needed to maintain the
vertical attitude because of the engine torque and
p-factor. When the plane has slowed enough, full rudder
initiates the turnaround. It is followed by right-forward
stick (right aileron and forward elevator) to keep
the plane from torquing off. The pivot is stopped
with opposite rudder when the nose points straight
down. When the pivot is completed, the ailerons and
rudder are neutralized. Elevator and rudder are used
to keep the nose pointing straight down. Thje pivot
must be completed within one wingspan. Rolls on the
downline require only aileron input if the plane is
trimmed correctly.
This maneuver is sometimes
called a hammerhead stall. This is not an accurate
name because the airplane never stalls. The airspeed
may be very low, close to zero, but since there is
now wingloading during the turn-around, there is no
stall (at zero g wing loading, a wing does not stall).
The plane is flying throughout the maneuver with all
the control surfaces effective (even sometimes only
marginally so).
This also is one of
the maneuvers that have been used to reverse direction
while adjusting altitude and airspeed by changing
the length of the down-line.
Humpty-Bump
The figure starts
with a quarter loop to a vertical climb. A half loop
then results in a vertical down-line. The figure completes
with another quarter loop to horizontal flight. The
looping part on the top of the figure does not have
to be the same radius as the two other looping portions
(the quarter loops going into and coming out of the
humpty). Again the figure can have optionally rolls
on both the up-line and the down-line.
Competition Turn
Competition turns
are not the coordinated maneuvers that you use in
normal flying. In a competition turn you first roll
to the desired bank. It has to be at least 60 degrees.
My experience shows that the steeper the bank, the
better the scores. I try to get close to 90 degrees
bank. Once the bank is established the turn is started.
The plane has to maintain a constant bank and altitude
throughout the turn. At the end of the turn the turn
is stopped and then the wings leveled for horizontal
flight. The example shows the symbol for a 270 degree
turn.
Rolling Turn
This maneuver combines
a turn with rolls. The example shows a 360 degree
turn with four rolls to the inside. The plane has
to maintain a constant roll rate, constant turn rate
and constant altitude throughout the rolling turn.
This maneuver is quite difficult to fly. It requires
constantly changing inputs from all three controls
(rudder, aileron, elevator).
Spin
Spins also are aerobatics
competition maneuvers. The two figures show a regular
and an inverted crossover one turn spin. Spins come
in 3/4, one, 1 1/4 and 1 1/2 turns.
During spin entry,
the plane has to show a stall break, followed by the
auto-rotation. The rotation has to stop exactly after
the specified number of turns. Once the rotation has
stopped, a vertical downline has to be established.
In a crossover spin,
the plane is first stalled upright. At the stall break,
the nose is pushed forward to get into an inverted
spin while maintaining the stall. The inverted spin
is then completed as it would be for an inverted spin
with entry from inverted flight.
Chandele
The Chandele is not
a figure for aerobatics competition. On the FAA power
commercial pilots test a Chandele is defined as a
maximum performance climbing turn through 180 degrees
while maintaining a constant turn rate. The idea is
that this is a "plan ahead" maneuver. You first establish
a medium bank depending on the performance of your
aircraft. Then a smooth pullup is started. The angle
of bank stays constant during the first 90 degrees
of turn, while the pitch angle increases steadily.
At the 90 degree point the plane has the maximum pitch
angle which should be close to the critical angle
of attack. During the second 90 degrees of turn, the
pitch angle is held constant, while the bank angle
is smoothly decreased to reach 0 degrees of bank at
180 degrees of turn with the airspeed close to the
stall speed. The plane should not settle during the
last part of the maneuver and the recovery. The decreasing
bank angle durning the second half of the Chandele
will maintain a constant turn rate together with the
decreasing airspeed. The turn needs to be kept coordinated
by applying the right amount of rudder. A Chandele
to the left is quite different than one to the right
because of the ever increasing amount of p-factor
in the second half of the maneuver.
Wing Over
The Wing-Over is a
competition maneuver in glider aerobatics. You pull
up and at the same time bank the plane. When the bank
increases past 45 degrees, the nose will start to
drop while the bank keeps increasing and the plane
keeps turning. Halfway through the maneuver, the plane
has turned 90 degrees, the fuselage is level with
the horizon and the bank is 90 degrees. The plane
is above the original flight path. The nose then keeps
dropping below the horizon and the plane keeps turning,
while the bank is shallowed. When the bank drops below
45 degrees, the nose is pulled up towards the horizon
and the plane reaches horizontal flight with wings
level after 180 degrees of turn. At the completion
of the maneuver, the plane is at the same altitude
as on entry and flying in the opposite direction.
Lazy Eight
Like the Chandele,
the Lazy Eight is not a competition maneuver but is
required for the power commercial pilot test. The
aerobatics version of the Lazy Eight is two wingovers
back to back. The FAA commercial pilot version is
similar but the maximum bank is only 45 degrees instead
of 90 degrees. The name Lazy Eight comes from the
fact that the nose of the airplane is following a
figure 8 on its side on the horizon
Barrel Roll
The Barrel Roll is
a not competition maneuver. I have tried to give a
description of a Barrel Roll without using my hands,
but have failed miserably so far. Maybe somebody else
has a good verbal description that doesn't require
hand waving.
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