THROUGH THE YEARS, I have heard
many extreme “3-D” pilots talk about
control-surface deflection, and I feel that
now is a great time to elaborate on this topic.
Many models on the radio-control market
today claim to be “3-D capable.” This mostly
means that their control surfaces are
extremely large, allowing the airplane to
perform many extreme maneuvers.
However, large amounts of control-surface
deflection are not always needed to
perform a given 3-D maneuver.
This month, I will write about the
advantages and disadvantages of using
extreme amounts of control-surface
deflection, in addition to the proper way to
measure control throw. Without further
hesitation, let’s begin!
deflection differs from airframe to
airframe, and it is directly related to your
model’s CG.
In the past month, I have logged many
hours on my 35% Hangar 9 Extra 260.
When I built this airplane, I obtained 55°
of elevator deflection and 40° of aileron
deflection. However, after I flew the
model, I decided to decrease both the
elevator and aileron deflection, and I will
reveal why.
The 55° of elevator deflection worked
well for performing common 3-D
maneuvers such as the Harrier and the
Elevator. However, one wingtip would
drop when I performed a hard push. Too
much control throw was used.
I decreased the elevator deflection 10°
(with the result of 42.5° of up and down
deflection), and now the Extra is crisp and
predictable while performing tight 3-D
maneuvers.
Please note that tip-stalling is common
in all Giant Scale aerobatic models.
Because of wing loading, total weight,
etc., it cannot be prevented. But by
changing the endpoint deflection as well
as the CG, the occurrence of a tip stall can
be minimized, which decreases the pilot’s
workload.
Regarding aileron throw, I found that
the factory-recommended settings of 34.4°
of up and 33° of down were more than
sufficient. The amount of desired aileron
throw will vary from pilot to pilot, but a
large amount is needed to perform a
demanding Freestyle routine.
need be, access the
ATV (adjustable
travel volume)
screen on your
computer radio and
make the necessary
adjustments.
Please note that
to obtain the best
resolution out of
your servo(s), it is
best to have ATV
values that are
close to maximum.
Next, you will
have to set up the
slave elevator half.
I find it helpful
to make a tool to
match the elevator
halves. I use two
clothing pins and
two large carbon rods that are roughly 18
inches long. I glue a carbon rod to a
clothespin using cyanoacrylate, and then I
replicate this item.
This tool is useful, because it clips to
the TE of the elevators so that I can
match the halves precisely. Since we have
already programmed the master elevator
half, clip on the elevator matching tools
and match the slave elevator with the
master (regarding endpoints).
Please make sure that the elevator
linkages are identical for both the right
and left elevator halves. Simply make
sure that the distance from the hinge line
to the control horn (to the point at which
the clevis or ball link is secured to the
control horn) is the same.
You have learned about some of the
142 MODEL AVIATION
Shown are the two carbon rods that are glued to clothespins. Using this tool, it’s easy to
ensure that each elevator half has the same deflection as the other.
The author’s high-rate elevator setting
indicates 42.5° of up and down elevator
deflection. If more control throw is used,
most models will exhibit undesired flight
characteristics.
Remember, though, that too much
throw will sometimes slow the roll rate
because of the large amount of drag
induced and potential blow-back to the
servo.
Measuring Control Throw Properly: I
cannot stress enough the importance of
taking time in the process of setting up
your model to ensure that it will perform
to the best of its ability. Too many times I
have seen modelers get discouraged
because an airplane does not perform as
they would like it to. But oftentimes, these
modelers have not taken the time that is
required in programming the model.
If one elevator half has even a slight
amount more control throw than the other
half, the model may exhibit a slight rolling
tendency whenever elevator is applied.
Similarly, if aileron deflection is not the
same in both the up and down deflection
before differential is applied, it will be
impossible to properly use aileron
differential, if needed, to perform an axial
roll.
I use the AnglePro 4-in-1 Digital
Throw/Incidence Meter by Hangar 9. This
device clips onto a control surface and is
used to check, in degrees, what the controlsurface
deflection is.
If you are setting up a Giant Scale
airplane that has two or more elevator
servos, you will connect the right elevator
half to the Elevator port on the receiver.
The left elevator half should plug into the
Slave port on the receiver. (This port will
vary depending on the transmitter you are
using.)
Make sure the right half (the master) is
centered, and check the up and down
deflection to ensure that they are equal. If
advantages and disadvantages of using
large amounts of control throw, how to
measure control throw, and how to
precisely match elevator halves.
Behind every great-flying airplane is a
great control setup. Always take your time
when building and programming your
aircraft, and seek advice from a fellow
expert modeler whenever you have a
question, or feel free to write to me.
Until next time, fly hard! MA
Sources:
Desert Aircraft
(520) 722-0607
www.desertaircraft.com
Hangar 9, JR:
Horizon Hobby, Inc.
(217) 352-1913
www.horizonhobby.com
The JR 12X radio’s dual rate and exponential screen details slightly
different elevator deflection amounts on low-rate elevator. Some
models react differently between a pull and a push. To make up for
this, change elevator deflection to suit your preference.
02sig5.QXD 12/22/08 11:32 AM Page 142
Edition: Model Aviation - 2009/02
Page Numbers: 141,142
Edition: Model Aviation - 2009/02
Page Numbers: 141,142
THROUGH THE YEARS, I have heard
many extreme “3-D” pilots talk about
control-surface deflection, and I feel that
now is a great time to elaborate on this topic.
Many models on the radio-control market
today claim to be “3-D capable.” This mostly
means that their control surfaces are
extremely large, allowing the airplane to
perform many extreme maneuvers.
However, large amounts of control-surface
deflection are not always needed to
perform a given 3-D maneuver.
This month, I will write about the
advantages and disadvantages of using
extreme amounts of control-surface
deflection, in addition to the proper way to
measure control throw. Without further
hesitation, let’s begin!
deflection differs from airframe to
airframe, and it is directly related to your
model’s CG.
In the past month, I have logged many
hours on my 35% Hangar 9 Extra 260.
When I built this airplane, I obtained 55°
of elevator deflection and 40° of aileron
deflection. However, after I flew the
model, I decided to decrease both the
elevator and aileron deflection, and I will
reveal why.
The 55° of elevator deflection worked
well for performing common 3-D
maneuvers such as the Harrier and the
Elevator. However, one wingtip would
drop when I performed a hard push. Too
much control throw was used.
I decreased the elevator deflection 10°
(with the result of 42.5° of up and down
deflection), and now the Extra is crisp and
predictable while performing tight 3-D
maneuvers.
Please note that tip-stalling is common
in all Giant Scale aerobatic models.
Because of wing loading, total weight,
etc., it cannot be prevented. But by
changing the endpoint deflection as well
as the CG, the occurrence of a tip stall can
be minimized, which decreases the pilot’s
workload.
Regarding aileron throw, I found that
the factory-recommended settings of 34.4°
of up and 33° of down were more than
sufficient. The amount of desired aileron
throw will vary from pilot to pilot, but a
large amount is needed to perform a
demanding Freestyle routine.
need be, access the
ATV (adjustable
travel volume)
screen on your
computer radio and
make the necessary
adjustments.
Please note that
to obtain the best
resolution out of
your servo(s), it is
best to have ATV
values that are
close to maximum.
Next, you will
have to set up the
slave elevator half.
I find it helpful
to make a tool to
match the elevator
halves. I use two
clothing pins and
two large carbon rods that are roughly 18
inches long. I glue a carbon rod to a
clothespin using cyanoacrylate, and then I
replicate this item.
This tool is useful, because it clips to
the TE of the elevators so that I can
match the halves precisely. Since we have
already programmed the master elevator
half, clip on the elevator matching tools
and match the slave elevator with the
master (regarding endpoints).
Please make sure that the elevator
linkages are identical for both the right
and left elevator halves. Simply make
sure that the distance from the hinge line
to the control horn (to the point at which
the clevis or ball link is secured to the
control horn) is the same.
You have learned about some of the
142 MODEL AVIATION
Shown are the two carbon rods that are glued to clothespins. Using this tool, it’s easy to
ensure that each elevator half has the same deflection as the other.
The author’s high-rate elevator setting
indicates 42.5° of up and down elevator
deflection. If more control throw is used,
most models will exhibit undesired flight
characteristics.
Remember, though, that too much
throw will sometimes slow the roll rate
because of the large amount of drag
induced and potential blow-back to the
servo.
Measuring Control Throw Properly: I
cannot stress enough the importance of
taking time in the process of setting up
your model to ensure that it will perform
to the best of its ability. Too many times I
have seen modelers get discouraged
because an airplane does not perform as
they would like it to. But oftentimes, these
modelers have not taken the time that is
required in programming the model.
If one elevator half has even a slight
amount more control throw than the other
half, the model may exhibit a slight rolling
tendency whenever elevator is applied.
Similarly, if aileron deflection is not the
same in both the up and down deflection
before differential is applied, it will be
impossible to properly use aileron
differential, if needed, to perform an axial
roll.
I use the AnglePro 4-in-1 Digital
Throw/Incidence Meter by Hangar 9. This
device clips onto a control surface and is
used to check, in degrees, what the controlsurface
deflection is.
If you are setting up a Giant Scale
airplane that has two or more elevator
servos, you will connect the right elevator
half to the Elevator port on the receiver.
The left elevator half should plug into the
Slave port on the receiver. (This port will
vary depending on the transmitter you are
using.)
Make sure the right half (the master) is
centered, and check the up and down
deflection to ensure that they are equal. If
advantages and disadvantages of using
large amounts of control throw, how to
measure control throw, and how to
precisely match elevator halves.
Behind every great-flying airplane is a
great control setup. Always take your time
when building and programming your
aircraft, and seek advice from a fellow
expert modeler whenever you have a
question, or feel free to write to me.
Until next time, fly hard! MA
Sources:
Desert Aircraft
(520) 722-0607
www.desertaircraft.com
Hangar 9, JR:
Horizon Hobby, Inc.
(217) 352-1913
www.horizonhobby.com
The JR 12X radio’s dual rate and exponential screen details slightly
different elevator deflection amounts on low-rate elevator. Some
models react differently between a pull and a push. To make up for
this, change elevator deflection to suit your preference.
02sig5.QXD 12/22/08 11:32 AM Page 142
