The Aresti 'Aerobatic Diagram' System
The following descriptions of the Aresti Aerobatic
Diagram System was provided courtesy of the Aircraft Proving Grounds
web site.
General Comment
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.
There are other figures that are not in the IAC
list of aerobatics figures. These include for instance the Aileron
roll and the Barrel roll. I will try to include some descriptions
of these too as I go along adding figures.
The K-values included with the competition figures give an indication
of the difficulty of each of these maneuvers. Higher K-values mean
more difficult maneuvers. This list is incomplete. If you would
like to see a figure included, please let me know about it and I
will put it in.
Click the "How To" button for a detail
explaination of how to perform some of these maneuvers with your
model. Additonal descriptions will be added in the future.
Straight Flight
All maneuvers must end in straight flight. The Aresti will show
either upright or inverted flight.
Upright & Inverted Flight
(K=2) (K=3)
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
Fig 1(K=10) Fig
2(K=7)
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
Fig 3 (K=13) Fig
4 (K=17)
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.
Loops (K=10)
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. 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 horizonal
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 (K=21)
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 (K=14)
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 (K=19)
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 eight loops that connect
the eight sides have to have the same radius at each corner.
Immelman (K=10)
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 (K=10)
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.
English Bunt (K=8)
This figure also is the second half of a loop downward, this time
an outside loop. You push forward and fly the second half of an
outside loop till you are in horizontal inverted flight. Make sure
you are not too fast going into the maneuver, otherwise you may
exceed redline speed.
Cuban Eight Maneuvers
Cuban Eight (K=29)
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 Cuban Eight (K=29)
Like the Cuban Eight, a Reverse Cuban Eight can be formed by
flying two Reverse Half Cuban Eights back to back.
Half Cuban Eight (K=14)
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.
Reverse Half Cuban Eight (K=16)
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.
Inside-Outside Eight (K=20)
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 (K=17)
It starts with 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. The 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 no 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 (although 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.
Tailslides (K=15) (K=15)
These maneuvers involve bringing the airplane to a complete stop
in a vertical attitude and then sliding back a visible amount. The
airplane must then tip over and fall through a vertical down
position. The left figure indicates a tailslide with the wheels down
during the flip, the right figure is a tailslide with the wheels up
(inverted) during the flip. Going into the figure and coming out,
the same rules apply as for other figures (quarter loops of constant
and equal radius, vertical lines).
Humpty-Bump (K=13)
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.
Turns
Competition Turn (K=5)
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 (K=20)
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 (K=14)
(K=18)
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.
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