Model Aviation 125
A guide for novice pilots
by John Glezellis
[email protected]
I would like to dedicate this month’s
column to the novice aerobatic pilot.
Too often, unfamiliar terminology is
used in the RC world. For example, for
the “newbie,” the meaning and proper
use of words such as exponential and
dual rates and/or triple rates may be
unclear.
I want to increase your knowledge
and understanding of the various practices that make each
of us better pilots, and those practices are all related to
properly tuning your aircraft to cater to your needs.
Because examples are essential, and to prove the various
points that will be made throughout this column, I will
begin by taking a look at Maneuver 10 from the 2012
Sportsman Known sequence. This stunt is a Humpty Bump that is performed on a
45° line.
From upright level flight, the pilot must push to a 45° downline and perform a
positive snap roll. Then, he or she must pull half of an inside loop to a 45° upline and
perform a half roll and push to upright level flight.
Some pilots may try flying this maneuver while staying on one rate. They may find
that the rolling and looping segments are erratic, but they need the control throw
when it comes time to perform the snap roll. There are multiple ways to customize
an airplane to perform this maneuver.
This month, I will discuss some different programming techniques that can be
used and share a few mistakes that I have seen experienced pilots make. Such errors
can make a stunt more difficult to perform.
PLUS:
> Decoding the
jargon
> Rates and
exponential
> Choosing the right
settings
> Flight modes
> Variable trace rate
Using Various Rates and Settings
Some radios feature what is called
dual rates. This means that the end
user can choose a reduced amount of
control surface deflection for a given
rate. In other words, you can select 25°
of aileron deflection for your low-rate
value, and 45° of aileron deflection for
your high-rate value—all with the flip of
a switch!
This can also be applied to the
other control surfaces of your aircraft.
However, more advanced radios feature
triple rates. This is similar to the dual
rate, but with an additional switch
position.
If you have been an avid reader of my
columns, you are aware that I use flight
modes to the fullest. I use both JR and
Spektrum equipment. Flight mode is
commonly associated with these two
manufacturers. Essentially, this means
that all rates can be combined onto one
switch. Rather than search for your
elevator rate switch or aileron switch,
you can use one switch for everything!
Because I am discussing combining
all rates onto one switch, I’ll review
Futaba’s definition of flight conditions.
Although conditions are flexible, by
allowing the end user the ability to
adjust his or her model on that specific
mode/switch position up to nearly
100%, they are separate from the basic
model setup. In its basic form, you can
apply all rates onto one switch—similar
to the way it is done in a flight mode. In addition to using either flight modes
or conditions, you can use Variable Trace
Rate (VTR), as long as your computer
radio features it. Using VTR is almost
like having two different linear rates in
one.
You can adjust the end-point values
for a given control surface in a specific
rate and can control the slope of the first
segment, which is your control authority,
while you move the stick to the end to
obtain the maximum amount of controlsurface
deflection.
Exponential (sometimes called expo),
is a curve that changes the control feel
around center stick. For example, if you
have an airplane that has 25° of aileron
throw with 0% expo, you have what
is called linear throw. Each stick input
corresponds exactly to the servo in a
linear fashion.
If you increase the exponential
percentage, the curve will become more
pronounced. Adding 30% expo with 25°
of aileron throw will make the airplane
slightly docile around center stick,
but you can still obtain the maximum
travel of 25° deflection once the aileron
stick is moved all the way to its max.
Exponential becomes beneficial when
you are trying to fly your aircraft in a
precise manner.
When softening the feel of a given
control surface around neutral stick,
Futaba radios
use negative
values and JR
and Spektrum
radios use
positive
exponential
values. If your
radio has a
graph, which
most do, you
will see that
the exponential
curve will
flatten out
around center
stick.
If you don’t
know which
direction to
go, try adding 100% of exponential on a
control surface and see how the control
stick responds around neutral. If it feels
soft, you are going in the right direction.
If you feel that the control surface is
extremely sensitive around neutral stick,
you have added exponential in the
wrong direction.
Let’s explore a few different options
for determining how much travel and
exponential are right for you.
The Right Settings
Enough with the definitions; let’s
go flying! Previously I mentioned a
specific maneuver. I did this so we can
discuss the different options that exist
when it comes time to set your rate
and exponential values in an effort to
obtain the exact feel you need from your
aircraft in a given maneuver.
Figure 10 worked out great. It
combined smooth, precise flight with
an aggressive snap roll, so the necessary
settings were diverse. I recommend that
you take a look at the following options
and see which approach will best suit
your needs.
Option 1: Three flight modes
and/or conditions
I prefer to use three flight modes. On
my 50cc Hangar 9 Yak 54, I divide these
modes in the following manner:
My first mode is for all rolling
maneuvers including rolling circles. With
this mode, I have roughly 12° of elevator
deflection, 20° of aileron deflection, and
approximately 35° of rudder deflection
with nearly 25% exponential on each rate.
Snaps and spins are performed on
my second flight mode, which has 20°
of elevator deflection, 35° of aileron defl ection, and roughly 30° of rudder
defl ection with approximately 40%
exponential on both the elevator and
rudder, and nearly 45% exponential on
the ailerons.
My third mode is for extreme 3-D
Aerobatics, where I have roughly 40°
of defl ection on all rates, and 65%
exponential across the line.
For a stunt such as Maneuver 10, I
need to perform everything but the
snap roll on my fi rst fl ight-mode setting.
Before the snap, I switch to my mid-rate
position. After executing the snap, I
switch back to low rates.
I have fl own with these settings for
years. I like the fact that my sequence is
divided with respect to rates. Whenever I
perform a new sequence, I know exactly
what rate to be on for each maneuver.
Option 2: The simplicity behind two
ight modes and/or conditions
One way that you can decrease your
rate-switching is to do exactly that.
Rather than have a different rate for
both snapping and rolling maneuvers,
why not combine them into one?
You will have one fl ight mode for
International Miniature Aerobatic Club
(IMAC)-style maneuvers and another
for extreme 3-D moves.
I recommend that you begin with
my “typical” snapping rate mentioned
in Option 1, which consists of
approximately 20° of elevator defl ection,
35° of aileron defl ection, and roughly
30° of rudder defl ection, but increase
the expo value to further soften the way
your aircraft reacts. With these settings,
I use approximately 50% of expo and
adjust the values after taking to the skies.
With the right settings, you can
perform a nice push to a 45° downline
and perform a positive snap by using
maximum defl ection on aileron and
rudder while unloading elevator.
Unloading a snap means that you
initially hold full up-elevator (if
performing a positive snap roll) to stall
the airplane. Then, apply maximum
aileron and rudder input in the direction
of your choice.
After the snap is complete, neutralize
inputs and continue with the half
inside loop and half roll that Maneuver
10 requires. The beauty of using one
primary rate is that you won’t have to
switch any rates while performing an
IMAC sequence!
If you want to perform 3-D
maneuvers, you can switch to your
second fl ight-mode position. That is
the only rate switching that will occur.
On this rate, I recommend you use
40° of defl ection on all surfaces with
approximately 65% of exponential.
The goal is to make the airplane
smooth on both rates, but particularly on
the rate at which your IMAC maneuvers
will be performed.
Option 3: VTR
As I mentioned in Opti on 2, some
pilots may wish to only fl y on one or
two rates. Some pilots prefer a linear feel
available with VTR because they want
a similar feel from the aircraft regarding
stick input.
Not all radios offer VTR. Consult the
instruction manual that was provided
with your radio to see if this is an option.
This is somewhat similar to the fi rst
mode in Option 2. You won’t have to
fl ip a switch when it comes time to
perform Maneuver 10 because your
maximum defl ection while using VTR
should never be more than what is
required to perform a snap roll. Never
use VTR for extreme control-surface
defl ection because the airplane will be
imprecise and twitchy.
On the other hand, it can be used
with success for small control-surface
defl ection amounts. Some pilots prefer a
linear response from their aircraft when
stick input is given.
Making Mistakes
Throughout the years, I have tuned
and inspected hundreds of airplanes for
others and have seen various mistakes
when it comes to using exponential,
fl ight modes, etc.
Some pilots apply a certain amount
of exponential on each rate, which
is correct. However, they use more
exponential on lower control-surface
defl ection amounts and higher amounts
of exponential when there is little
defl ection on a given rate. They mixed
up the exponential values, and what
should have been the percentage that
corresponded with their low-rate setting,
was applied to their high-rate value!
I have also seen cases in which
someone used the wrong value of
exponential, resulting in an extremely
sensitive airplane around neutral.
Always consult the instruction manual
provided with your radio to see what
value you need, and whether value has
to be positive or negative. Taking a few
extra minutes can save you a headache
at the fi eld!
Another situation that I have
encountered is where a pilot utilizes
one rate for all types of fl ying. He or she
uses a rate that applies 35° of control
travel for precision and 3-D maneuvers!
How can you expect your airplane to fl y
smoothly when that amount of travel is
being used? It’s not possible!
Final Thoughts
I want to emphasize that all pilots
have different preferences, and what
may work for one person may not for
another. In this column, I dissected
a specifi c maneuver, discussed a few
different ways in which a person can
perform this fi gure, and covered a few
key areas that must not be overlooked.
Even experienced aviators can make
mistakes.
It is important to have an airplane
properly set up to save time. I like
to examine the aircraft and its radio
programming before fl ying. A pilot also
must know his or her capabilities, as well
as those of the transmitter, to succeed on
the fl ightline.
So many great designs exist that it is
rare to fi nd a poor-fl ying Giant Scale
airplane.
Edition: Model Aviation - 2012/08
Page Numbers: 125,126,127,128
Edition: Model Aviation - 2012/08
Page Numbers: 125,126,127,128
Model Aviation 125
A guide for novice pilots
by John Glezellis
[email protected]
I would like to dedicate this month’s
column to the novice aerobatic pilot.
Too often, unfamiliar terminology is
used in the RC world. For example, for
the “newbie,” the meaning and proper
use of words such as exponential and
dual rates and/or triple rates may be
unclear.
I want to increase your knowledge
and understanding of the various practices that make each
of us better pilots, and those practices are all related to
properly tuning your aircraft to cater to your needs.
Because examples are essential, and to prove the various
points that will be made throughout this column, I will
begin by taking a look at Maneuver 10 from the 2012
Sportsman Known sequence. This stunt is a Humpty Bump that is performed on a
45° line.
From upright level flight, the pilot must push to a 45° downline and perform a
positive snap roll. Then, he or she must pull half of an inside loop to a 45° upline and
perform a half roll and push to upright level flight.
Some pilots may try flying this maneuver while staying on one rate. They may find
that the rolling and looping segments are erratic, but they need the control throw
when it comes time to perform the snap roll. There are multiple ways to customize
an airplane to perform this maneuver.
This month, I will discuss some different programming techniques that can be
used and share a few mistakes that I have seen experienced pilots make. Such errors
can make a stunt more difficult to perform.
PLUS:
> Decoding the
jargon
> Rates and
exponential
> Choosing the right
settings
> Flight modes
> Variable trace rate
Using Various Rates and Settings
Some radios feature what is called
dual rates. This means that the end
user can choose a reduced amount of
control surface deflection for a given
rate. In other words, you can select 25°
of aileron deflection for your low-rate
value, and 45° of aileron deflection for
your high-rate value—all with the flip of
a switch!
This can also be applied to the
other control surfaces of your aircraft.
However, more advanced radios feature
triple rates. This is similar to the dual
rate, but with an additional switch
position.
If you have been an avid reader of my
columns, you are aware that I use flight
modes to the fullest. I use both JR and
Spektrum equipment. Flight mode is
commonly associated with these two
manufacturers. Essentially, this means
that all rates can be combined onto one
switch. Rather than search for your
elevator rate switch or aileron switch,
you can use one switch for everything!
Because I am discussing combining
all rates onto one switch, I’ll review
Futaba’s definition of flight conditions.
Although conditions are flexible, by
allowing the end user the ability to
adjust his or her model on that specific
mode/switch position up to nearly
100%, they are separate from the basic
model setup. In its basic form, you can
apply all rates onto one switch—similar
to the way it is done in a flight mode. In addition to using either flight modes
or conditions, you can use Variable Trace
Rate (VTR), as long as your computer
radio features it. Using VTR is almost
like having two different linear rates in
one.
You can adjust the end-point values
for a given control surface in a specific
rate and can control the slope of the first
segment, which is your control authority,
while you move the stick to the end to
obtain the maximum amount of controlsurface
deflection.
Exponential (sometimes called expo),
is a curve that changes the control feel
around center stick. For example, if you
have an airplane that has 25° of aileron
throw with 0% expo, you have what
is called linear throw. Each stick input
corresponds exactly to the servo in a
linear fashion.
If you increase the exponential
percentage, the curve will become more
pronounced. Adding 30% expo with 25°
of aileron throw will make the airplane
slightly docile around center stick,
but you can still obtain the maximum
travel of 25° deflection once the aileron
stick is moved all the way to its max.
Exponential becomes beneficial when
you are trying to fly your aircraft in a
precise manner.
When softening the feel of a given
control surface around neutral stick,
Futaba radios
use negative
values and JR
and Spektrum
radios use
positive
exponential
values. If your
radio has a
graph, which
most do, you
will see that
the exponential
curve will
flatten out
around center
stick.
If you don’t
know which
direction to
go, try adding 100% of exponential on a
control surface and see how the control
stick responds around neutral. If it feels
soft, you are going in the right direction.
If you feel that the control surface is
extremely sensitive around neutral stick,
you have added exponential in the
wrong direction.
Let’s explore a few different options
for determining how much travel and
exponential are right for you.
The Right Settings
Enough with the definitions; let’s
go flying! Previously I mentioned a
specific maneuver. I did this so we can
discuss the different options that exist
when it comes time to set your rate
and exponential values in an effort to
obtain the exact feel you need from your
aircraft in a given maneuver.
Figure 10 worked out great. It
combined smooth, precise flight with
an aggressive snap roll, so the necessary
settings were diverse. I recommend that
you take a look at the following options
and see which approach will best suit
your needs.
Option 1: Three flight modes
and/or conditions
I prefer to use three flight modes. On
my 50cc Hangar 9 Yak 54, I divide these
modes in the following manner:
My first mode is for all rolling
maneuvers including rolling circles. With
this mode, I have roughly 12° of elevator
deflection, 20° of aileron deflection, and
approximately 35° of rudder deflection
with nearly 25% exponential on each rate.
Snaps and spins are performed on
my second flight mode, which has 20°
of elevator deflection, 35° of aileron defl ection, and roughly 30° of rudder
defl ection with approximately 40%
exponential on both the elevator and
rudder, and nearly 45% exponential on
the ailerons.
My third mode is for extreme 3-D
Aerobatics, where I have roughly 40°
of defl ection on all rates, and 65%
exponential across the line.
For a stunt such as Maneuver 10, I
need to perform everything but the
snap roll on my fi rst fl ight-mode setting.
Before the snap, I switch to my mid-rate
position. After executing the snap, I
switch back to low rates.
I have fl own with these settings for
years. I like the fact that my sequence is
divided with respect to rates. Whenever I
perform a new sequence, I know exactly
what rate to be on for each maneuver.
Option 2: The simplicity behind two
ight modes and/or conditions
One way that you can decrease your
rate-switching is to do exactly that.
Rather than have a different rate for
both snapping and rolling maneuvers,
why not combine them into one?
You will have one fl ight mode for
International Miniature Aerobatic Club
(IMAC)-style maneuvers and another
for extreme 3-D moves.
I recommend that you begin with
my “typical” snapping rate mentioned
in Option 1, which consists of
approximately 20° of elevator defl ection,
35° of aileron defl ection, and roughly
30° of rudder defl ection, but increase
the expo value to further soften the way
your aircraft reacts. With these settings,
I use approximately 50% of expo and
adjust the values after taking to the skies.
With the right settings, you can
perform a nice push to a 45° downline
and perform a positive snap by using
maximum defl ection on aileron and
rudder while unloading elevator.
Unloading a snap means that you
initially hold full up-elevator (if
performing a positive snap roll) to stall
the airplane. Then, apply maximum
aileron and rudder input in the direction
of your choice.
After the snap is complete, neutralize
inputs and continue with the half
inside loop and half roll that Maneuver
10 requires. The beauty of using one
primary rate is that you won’t have to
switch any rates while performing an
IMAC sequence!
If you want to perform 3-D
maneuvers, you can switch to your
second fl ight-mode position. That is
the only rate switching that will occur.
On this rate, I recommend you use
40° of defl ection on all surfaces with
approximately 65% of exponential.
The goal is to make the airplane
smooth on both rates, but particularly on
the rate at which your IMAC maneuvers
will be performed.
Option 3: VTR
As I mentioned in Opti on 2, some
pilots may wish to only fl y on one or
two rates. Some pilots prefer a linear feel
available with VTR because they want
a similar feel from the aircraft regarding
stick input.
Not all radios offer VTR. Consult the
instruction manual that was provided
with your radio to see if this is an option.
This is somewhat similar to the fi rst
mode in Option 2. You won’t have to
fl ip a switch when it comes time to
perform Maneuver 10 because your
maximum defl ection while using VTR
should never be more than what is
required to perform a snap roll. Never
use VTR for extreme control-surface
defl ection because the airplane will be
imprecise and twitchy.
On the other hand, it can be used
with success for small control-surface
defl ection amounts. Some pilots prefer a
linear response from their aircraft when
stick input is given.
Making Mistakes
Throughout the years, I have tuned
and inspected hundreds of airplanes for
others and have seen various mistakes
when it comes to using exponential,
fl ight modes, etc.
Some pilots apply a certain amount
of exponential on each rate, which
is correct. However, they use more
exponential on lower control-surface
defl ection amounts and higher amounts
of exponential when there is little
defl ection on a given rate. They mixed
up the exponential values, and what
should have been the percentage that
corresponded with their low-rate setting,
was applied to their high-rate value!
I have also seen cases in which
someone used the wrong value of
exponential, resulting in an extremely
sensitive airplane around neutral.
Always consult the instruction manual
provided with your radio to see what
value you need, and whether value has
to be positive or negative. Taking a few
extra minutes can save you a headache
at the fi eld!
Another situation that I have
encountered is where a pilot utilizes
one rate for all types of fl ying. He or she
uses a rate that applies 35° of control
travel for precision and 3-D maneuvers!
How can you expect your airplane to fl y
smoothly when that amount of travel is
being used? It’s not possible!
Final Thoughts
I want to emphasize that all pilots
have different preferences, and what
may work for one person may not for
another. In this column, I dissected
a specifi c maneuver, discussed a few
different ways in which a person can
perform this fi gure, and covered a few
key areas that must not be overlooked.
Even experienced aviators can make
mistakes.
It is important to have an airplane
properly set up to save time. I like
to examine the aircraft and its radio
programming before fl ying. A pilot also
must know his or her capabilities, as well
as those of the transmitter, to succeed on
the fl ightline.
So many great designs exist that it is
rare to fi nd a poor-fl ying Giant Scale
airplane.
Edition: Model Aviation - 2012/08
Page Numbers: 125,126,127,128
Model Aviation 125
A guide for novice pilots
by John Glezellis
[email protected]
I would like to dedicate this month’s
column to the novice aerobatic pilot.
Too often, unfamiliar terminology is
used in the RC world. For example, for
the “newbie,” the meaning and proper
use of words such as exponential and
dual rates and/or triple rates may be
unclear.
I want to increase your knowledge
and understanding of the various practices that make each
of us better pilots, and those practices are all related to
properly tuning your aircraft to cater to your needs.
Because examples are essential, and to prove the various
points that will be made throughout this column, I will
begin by taking a look at Maneuver 10 from the 2012
Sportsman Known sequence. This stunt is a Humpty Bump that is performed on a
45° line.
From upright level flight, the pilot must push to a 45° downline and perform a
positive snap roll. Then, he or she must pull half of an inside loop to a 45° upline and
perform a half roll and push to upright level flight.
Some pilots may try flying this maneuver while staying on one rate. They may find
that the rolling and looping segments are erratic, but they need the control throw
when it comes time to perform the snap roll. There are multiple ways to customize
an airplane to perform this maneuver.
This month, I will discuss some different programming techniques that can be
used and share a few mistakes that I have seen experienced pilots make. Such errors
can make a stunt more difficult to perform.
PLUS:
> Decoding the
jargon
> Rates and
exponential
> Choosing the right
settings
> Flight modes
> Variable trace rate
Using Various Rates and Settings
Some radios feature what is called
dual rates. This means that the end
user can choose a reduced amount of
control surface deflection for a given
rate. In other words, you can select 25°
of aileron deflection for your low-rate
value, and 45° of aileron deflection for
your high-rate value—all with the flip of
a switch!
This can also be applied to the
other control surfaces of your aircraft.
However, more advanced radios feature
triple rates. This is similar to the dual
rate, but with an additional switch
position.
If you have been an avid reader of my
columns, you are aware that I use flight
modes to the fullest. I use both JR and
Spektrum equipment. Flight mode is
commonly associated with these two
manufacturers. Essentially, this means
that all rates can be combined onto one
switch. Rather than search for your
elevator rate switch or aileron switch,
you can use one switch for everything!
Because I am discussing combining
all rates onto one switch, I’ll review
Futaba’s definition of flight conditions.
Although conditions are flexible, by
allowing the end user the ability to
adjust his or her model on that specific
mode/switch position up to nearly
100%, they are separate from the basic
model setup. In its basic form, you can
apply all rates onto one switch—similar
to the way it is done in a flight mode. In addition to using either flight modes
or conditions, you can use Variable Trace
Rate (VTR), as long as your computer
radio features it. Using VTR is almost
like having two different linear rates in
one.
You can adjust the end-point values
for a given control surface in a specific
rate and can control the slope of the first
segment, which is your control authority,
while you move the stick to the end to
obtain the maximum amount of controlsurface
deflection.
Exponential (sometimes called expo),
is a curve that changes the control feel
around center stick. For example, if you
have an airplane that has 25° of aileron
throw with 0% expo, you have what
is called linear throw. Each stick input
corresponds exactly to the servo in a
linear fashion.
If you increase the exponential
percentage, the curve will become more
pronounced. Adding 30% expo with 25°
of aileron throw will make the airplane
slightly docile around center stick,
but you can still obtain the maximum
travel of 25° deflection once the aileron
stick is moved all the way to its max.
Exponential becomes beneficial when
you are trying to fly your aircraft in a
precise manner.
When softening the feel of a given
control surface around neutral stick,
Futaba radios
use negative
values and JR
and Spektrum
radios use
positive
exponential
values. If your
radio has a
graph, which
most do, you
will see that
the exponential
curve will
flatten out
around center
stick.
If you don’t
know which
direction to
go, try adding 100% of exponential on a
control surface and see how the control
stick responds around neutral. If it feels
soft, you are going in the right direction.
If you feel that the control surface is
extremely sensitive around neutral stick,
you have added exponential in the
wrong direction.
Let’s explore a few different options
for determining how much travel and
exponential are right for you.
The Right Settings
Enough with the definitions; let’s
go flying! Previously I mentioned a
specific maneuver. I did this so we can
discuss the different options that exist
when it comes time to set your rate
and exponential values in an effort to
obtain the exact feel you need from your
aircraft in a given maneuver.
Figure 10 worked out great. It
combined smooth, precise flight with
an aggressive snap roll, so the necessary
settings were diverse. I recommend that
you take a look at the following options
and see which approach will best suit
your needs.
Option 1: Three flight modes
and/or conditions
I prefer to use three flight modes. On
my 50cc Hangar 9 Yak 54, I divide these
modes in the following manner:
My first mode is for all rolling
maneuvers including rolling circles. With
this mode, I have roughly 12° of elevator
deflection, 20° of aileron deflection, and
approximately 35° of rudder deflection
with nearly 25% exponential on each rate.
Snaps and spins are performed on
my second flight mode, which has 20°
of elevator deflection, 35° of aileron defl ection, and roughly 30° of rudder
defl ection with approximately 40%
exponential on both the elevator and
rudder, and nearly 45% exponential on
the ailerons.
My third mode is for extreme 3-D
Aerobatics, where I have roughly 40°
of defl ection on all rates, and 65%
exponential across the line.
For a stunt such as Maneuver 10, I
need to perform everything but the
snap roll on my fi rst fl ight-mode setting.
Before the snap, I switch to my mid-rate
position. After executing the snap, I
switch back to low rates.
I have fl own with these settings for
years. I like the fact that my sequence is
divided with respect to rates. Whenever I
perform a new sequence, I know exactly
what rate to be on for each maneuver.
Option 2: The simplicity behind two
ight modes and/or conditions
One way that you can decrease your
rate-switching is to do exactly that.
Rather than have a different rate for
both snapping and rolling maneuvers,
why not combine them into one?
You will have one fl ight mode for
International Miniature Aerobatic Club
(IMAC)-style maneuvers and another
for extreme 3-D moves.
I recommend that you begin with
my “typical” snapping rate mentioned
in Option 1, which consists of
approximately 20° of elevator defl ection,
35° of aileron defl ection, and roughly
30° of rudder defl ection, but increase
the expo value to further soften the way
your aircraft reacts. With these settings,
I use approximately 50% of expo and
adjust the values after taking to the skies.
With the right settings, you can
perform a nice push to a 45° downline
and perform a positive snap by using
maximum defl ection on aileron and
rudder while unloading elevator.
Unloading a snap means that you
initially hold full up-elevator (if
performing a positive snap roll) to stall
the airplane. Then, apply maximum
aileron and rudder input in the direction
of your choice.
After the snap is complete, neutralize
inputs and continue with the half
inside loop and half roll that Maneuver
10 requires. The beauty of using one
primary rate is that you won’t have to
switch any rates while performing an
IMAC sequence!
If you want to perform 3-D
maneuvers, you can switch to your
second fl ight-mode position. That is
the only rate switching that will occur.
On this rate, I recommend you use
40° of defl ection on all surfaces with
approximately 65% of exponential.
The goal is to make the airplane
smooth on both rates, but particularly on
the rate at which your IMAC maneuvers
will be performed.
Option 3: VTR
As I mentioned in Opti on 2, some
pilots may wish to only fl y on one or
two rates. Some pilots prefer a linear feel
available with VTR because they want
a similar feel from the aircraft regarding
stick input.
Not all radios offer VTR. Consult the
instruction manual that was provided
with your radio to see if this is an option.
This is somewhat similar to the fi rst
mode in Option 2. You won’t have to
fl ip a switch when it comes time to
perform Maneuver 10 because your
maximum defl ection while using VTR
should never be more than what is
required to perform a snap roll. Never
use VTR for extreme control-surface
defl ection because the airplane will be
imprecise and twitchy.
On the other hand, it can be used
with success for small control-surface
defl ection amounts. Some pilots prefer a
linear response from their aircraft when
stick input is given.
Making Mistakes
Throughout the years, I have tuned
and inspected hundreds of airplanes for
others and have seen various mistakes
when it comes to using exponential,
fl ight modes, etc.
Some pilots apply a certain amount
of exponential on each rate, which
is correct. However, they use more
exponential on lower control-surface
defl ection amounts and higher amounts
of exponential when there is little
defl ection on a given rate. They mixed
up the exponential values, and what
should have been the percentage that
corresponded with their low-rate setting,
was applied to their high-rate value!
I have also seen cases in which
someone used the wrong value of
exponential, resulting in an extremely
sensitive airplane around neutral.
Always consult the instruction manual
provided with your radio to see what
value you need, and whether value has
to be positive or negative. Taking a few
extra minutes can save you a headache
at the fi eld!
Another situation that I have
encountered is where a pilot utilizes
one rate for all types of fl ying. He or she
uses a rate that applies 35° of control
travel for precision and 3-D maneuvers!
How can you expect your airplane to fl y
smoothly when that amount of travel is
being used? It’s not possible!
Final Thoughts
I want to emphasize that all pilots
have different preferences, and what
may work for one person may not for
another. In this column, I dissected
a specifi c maneuver, discussed a few
different ways in which a person can
perform this fi gure, and covered a few
key areas that must not be overlooked.
Even experienced aviators can make
mistakes.
It is important to have an airplane
properly set up to save time. I like
to examine the aircraft and its radio
programming before fl ying. A pilot also
must know his or her capabilities, as well
as those of the transmitter, to succeed on
the fl ightline.
So many great designs exist that it is
rare to fi nd a poor-fl ying Giant Scale
airplane.
Edition: Model Aviation - 2012/08
Page Numbers: 125,126,127,128
Model Aviation 125
A guide for novice pilots
by John Glezellis
[email protected]
I would like to dedicate this month’s
column to the novice aerobatic pilot.
Too often, unfamiliar terminology is
used in the RC world. For example, for
the “newbie,” the meaning and proper
use of words such as exponential and
dual rates and/or triple rates may be
unclear.
I want to increase your knowledge
and understanding of the various practices that make each
of us better pilots, and those practices are all related to
properly tuning your aircraft to cater to your needs.
Because examples are essential, and to prove the various
points that will be made throughout this column, I will
begin by taking a look at Maneuver 10 from the 2012
Sportsman Known sequence. This stunt is a Humpty Bump that is performed on a
45° line.
From upright level flight, the pilot must push to a 45° downline and perform a
positive snap roll. Then, he or she must pull half of an inside loop to a 45° upline and
perform a half roll and push to upright level flight.
Some pilots may try flying this maneuver while staying on one rate. They may find
that the rolling and looping segments are erratic, but they need the control throw
when it comes time to perform the snap roll. There are multiple ways to customize
an airplane to perform this maneuver.
This month, I will discuss some different programming techniques that can be
used and share a few mistakes that I have seen experienced pilots make. Such errors
can make a stunt more difficult to perform.
PLUS:
> Decoding the
jargon
> Rates and
exponential
> Choosing the right
settings
> Flight modes
> Variable trace rate
Using Various Rates and Settings
Some radios feature what is called
dual rates. This means that the end
user can choose a reduced amount of
control surface deflection for a given
rate. In other words, you can select 25°
of aileron deflection for your low-rate
value, and 45° of aileron deflection for
your high-rate value—all with the flip of
a switch!
This can also be applied to the
other control surfaces of your aircraft.
However, more advanced radios feature
triple rates. This is similar to the dual
rate, but with an additional switch
position.
If you have been an avid reader of my
columns, you are aware that I use flight
modes to the fullest. I use both JR and
Spektrum equipment. Flight mode is
commonly associated with these two
manufacturers. Essentially, this means
that all rates can be combined onto one
switch. Rather than search for your
elevator rate switch or aileron switch,
you can use one switch for everything!
Because I am discussing combining
all rates onto one switch, I’ll review
Futaba’s definition of flight conditions.
Although conditions are flexible, by
allowing the end user the ability to
adjust his or her model on that specific
mode/switch position up to nearly
100%, they are separate from the basic
model setup. In its basic form, you can
apply all rates onto one switch—similar
to the way it is done in a flight mode. In addition to using either flight modes
or conditions, you can use Variable Trace
Rate (VTR), as long as your computer
radio features it. Using VTR is almost
like having two different linear rates in
one.
You can adjust the end-point values
for a given control surface in a specific
rate and can control the slope of the first
segment, which is your control authority,
while you move the stick to the end to
obtain the maximum amount of controlsurface
deflection.
Exponential (sometimes called expo),
is a curve that changes the control feel
around center stick. For example, if you
have an airplane that has 25° of aileron
throw with 0% expo, you have what
is called linear throw. Each stick input
corresponds exactly to the servo in a
linear fashion.
If you increase the exponential
percentage, the curve will become more
pronounced. Adding 30% expo with 25°
of aileron throw will make the airplane
slightly docile around center stick,
but you can still obtain the maximum
travel of 25° deflection once the aileron
stick is moved all the way to its max.
Exponential becomes beneficial when
you are trying to fly your aircraft in a
precise manner.
When softening the feel of a given
control surface around neutral stick,
Futaba radios
use negative
values and JR
and Spektrum
radios use
positive
exponential
values. If your
radio has a
graph, which
most do, you
will see that
the exponential
curve will
flatten out
around center
stick.
If you don’t
know which
direction to
go, try adding 100% of exponential on a
control surface and see how the control
stick responds around neutral. If it feels
soft, you are going in the right direction.
If you feel that the control surface is
extremely sensitive around neutral stick,
you have added exponential in the
wrong direction.
Let’s explore a few different options
for determining how much travel and
exponential are right for you.
The Right Settings
Enough with the definitions; let’s
go flying! Previously I mentioned a
specific maneuver. I did this so we can
discuss the different options that exist
when it comes time to set your rate
and exponential values in an effort to
obtain the exact feel you need from your
aircraft in a given maneuver.
Figure 10 worked out great. It
combined smooth, precise flight with
an aggressive snap roll, so the necessary
settings were diverse. I recommend that
you take a look at the following options
and see which approach will best suit
your needs.
Option 1: Three flight modes
and/or conditions
I prefer to use three flight modes. On
my 50cc Hangar 9 Yak 54, I divide these
modes in the following manner:
My first mode is for all rolling
maneuvers including rolling circles. With
this mode, I have roughly 12° of elevator
deflection, 20° of aileron deflection, and
approximately 35° of rudder deflection
with nearly 25% exponential on each rate.
Snaps and spins are performed on
my second flight mode, which has 20°
of elevator deflection, 35° of aileron defl ection, and roughly 30° of rudder
defl ection with approximately 40%
exponential on both the elevator and
rudder, and nearly 45% exponential on
the ailerons.
My third mode is for extreme 3-D
Aerobatics, where I have roughly 40°
of defl ection on all rates, and 65%
exponential across the line.
For a stunt such as Maneuver 10, I
need to perform everything but the
snap roll on my fi rst fl ight-mode setting.
Before the snap, I switch to my mid-rate
position. After executing the snap, I
switch back to low rates.
I have fl own with these settings for
years. I like the fact that my sequence is
divided with respect to rates. Whenever I
perform a new sequence, I know exactly
what rate to be on for each maneuver.
Option 2: The simplicity behind two
ight modes and/or conditions
One way that you can decrease your
rate-switching is to do exactly that.
Rather than have a different rate for
both snapping and rolling maneuvers,
why not combine them into one?
You will have one fl ight mode for
International Miniature Aerobatic Club
(IMAC)-style maneuvers and another
for extreme 3-D moves.
I recommend that you begin with
my “typical” snapping rate mentioned
in Option 1, which consists of
approximately 20° of elevator defl ection,
35° of aileron defl ection, and roughly
30° of rudder defl ection, but increase
the expo value to further soften the way
your aircraft reacts. With these settings,
I use approximately 50% of expo and
adjust the values after taking to the skies.
With the right settings, you can
perform a nice push to a 45° downline
and perform a positive snap by using
maximum defl ection on aileron and
rudder while unloading elevator.
Unloading a snap means that you
initially hold full up-elevator (if
performing a positive snap roll) to stall
the airplane. Then, apply maximum
aileron and rudder input in the direction
of your choice.
After the snap is complete, neutralize
inputs and continue with the half
inside loop and half roll that Maneuver
10 requires. The beauty of using one
primary rate is that you won’t have to
switch any rates while performing an
IMAC sequence!
If you want to perform 3-D
maneuvers, you can switch to your
second fl ight-mode position. That is
the only rate switching that will occur.
On this rate, I recommend you use
40° of defl ection on all surfaces with
approximately 65% of exponential.
The goal is to make the airplane
smooth on both rates, but particularly on
the rate at which your IMAC maneuvers
will be performed.
Option 3: VTR
As I mentioned in Opti on 2, some
pilots may wish to only fl y on one or
two rates. Some pilots prefer a linear feel
available with VTR because they want
a similar feel from the aircraft regarding
stick input.
Not all radios offer VTR. Consult the
instruction manual that was provided
with your radio to see if this is an option.
This is somewhat similar to the fi rst
mode in Option 2. You won’t have to
fl ip a switch when it comes time to
perform Maneuver 10 because your
maximum defl ection while using VTR
should never be more than what is
required to perform a snap roll. Never
use VTR for extreme control-surface
defl ection because the airplane will be
imprecise and twitchy.
On the other hand, it can be used
with success for small control-surface
defl ection amounts. Some pilots prefer a
linear response from their aircraft when
stick input is given.
Making Mistakes
Throughout the years, I have tuned
and inspected hundreds of airplanes for
others and have seen various mistakes
when it comes to using exponential,
fl ight modes, etc.
Some pilots apply a certain amount
of exponential on each rate, which
is correct. However, they use more
exponential on lower control-surface
defl ection amounts and higher amounts
of exponential when there is little
defl ection on a given rate. They mixed
up the exponential values, and what
should have been the percentage that
corresponded with their low-rate setting,
was applied to their high-rate value!
I have also seen cases in which
someone used the wrong value of
exponential, resulting in an extremely
sensitive airplane around neutral.
Always consult the instruction manual
provided with your radio to see what
value you need, and whether value has
to be positive or negative. Taking a few
extra minutes can save you a headache
at the fi eld!
Another situation that I have
encountered is where a pilot utilizes
one rate for all types of fl ying. He or she
uses a rate that applies 35° of control
travel for precision and 3-D maneuvers!
How can you expect your airplane to fl y
smoothly when that amount of travel is
being used? It’s not possible!
Final Thoughts
I want to emphasize that all pilots
have different preferences, and what
may work for one person may not for
another. In this column, I dissected
a specifi c maneuver, discussed a few
different ways in which a person can
perform this fi gure, and covered a few
key areas that must not be overlooked.
Even experienced aviators can make
mistakes.
It is important to have an airplane
properly set up to save time. I like
to examine the aircraft and its radio
programming before fl ying. A pilot also
must know his or her capabilities, as well
as those of the transmitter, to succeed on
the fl ightline.
So many great designs exist that it is
rare to fi nd a poor-fl ying Giant Scale
airplane.
