Equipment weight savings greatly affects flight performance
August 2008 143
[[email protected]]
Radio Control Scale Aerobatics John Glezellis
to take full advantage of a given radio system
and the mixing capabilities it offers.
By using a 14-channel receiver (and the
14MZ radio system), I was able to mix all
four aileron servos so that no servo
synchronizers were needed. The same was
done for the elevator servos. (One channel
was the “master” elevator channel and one
channel was the “slave” elevator channel.)
Using a computer radio’s mixing
capabilities is important when it comes to
trimming your aircraft. Let’s look at the basic,
one-servo-per-aileron configuration.
I often see modelers use a “Y harness” to
make two servos work together for a given
function. However, if a Y harness is used, a
modeler cannot adjust each servo
are required). Let’s take a look at the weight
savings.
By reducing the elevator servos to only
one per half, a total weight of 14.4 ounces per
stabilizer half was obtained (compared to the
original weight of 18.2 ounces). A total
weight savings of 4.2 ounces was reduced per
stabilizer half, which results in a total savings
of 8.4 ounces.
The aircraft’s flight characteristics change
quite a bit when this amount of weight is
taken out—especially when it is taken out of
the tail.
Using Your Computer Radio Wisely: Today,
it is common to see many fliers use a ninechannel
or more radio system. It is important
LAST TIME, I wrote about the benefits of
using both Flight Modes and Flight
Conditions. This month we will look at a few
different ways in which a person can improve
his or her aircraft’s performance.
When I built my 38% Great Planes Extra
330S, I used one servo synchronizer per
aileron, one servo synchronizer per elevator
half, and one servo synchronizer on the
rudder. This resulted in the use of five servo
synchronizers.
In addition, I used two servos per elevator
half (I used the Futaba S9155, which offers
192 ounce-inch at 6.0 volts). I used two ninechannel
receivers on the airplane for
redundancy.
However, I recently converted this aircraft
to 2.4 GHz and selected a 14-channel
receiver. Therefore, the need for servo
synchronizers diminished.
All in all, each servo synchronizer has a
total weight of approximately .46 ounce. That
may not seem like a lot, but it can have a great
impact on your model’s flight performance,
depending on its location within the aircraft.
A few additional ounces of weight on the
CG will not change how your model
transitions from upright to inverted flight. But
a few ounces in the tail will (because of the
greater moment from the tail to the CG point).
Servo Talk: When considering elevator
servos for your giant-scale aerobatic aircraft,
look at the servo’s torque at 6.0 volts. When
40% airplanes were first introduced, it was
common to use two servos per elevator half
(and it still is, in some circumstances),
because the servos did not have enough
output. Today, many manufacturers have
servos with more than 300 ounce-inch of
torque at 6.0 volts.
JR has the 8711 (that has a total of 403
ounce-inch at 6.0 volts), Futaba has the S9156
(that has a total of 340 ounce-inch at 6.0
volts), and Hobbico and Hitec offer the CS-
170 and the HS-5955 (that each offer 333.0
ounce-inch at 6.0 volts). By selecting the right
servo for a given application, you can reduce
the number of servos you employ for a given
control surface.
In the 38% Extra 330S, I went from using
two servos per half (that give a total of
roughly 192 ounce-inch of torque each) to
only one servo per elevator half (each giving
330 ounce-inch of torque).
Now, not only does the modeler save
weight by reducing the number of servos, but
he or she also reduces the number of servo
extensions and the number of servo
synchronizers that are needed. (Two servo
synchronizers were originally used; now none
When programming a new model on the
Futaba 14MZ, the end user can select
wing and tail type. Here, two channels are
being used for both ailerons (one for
“master” channel; one for “slave”
channel) as well as elevators.
By using one servo per elevator half, a
great amount of weight (approximately 8.4
ounces total) has been saved from the tail.
The author with the Hacker-powered Pitts Python he flew at the 2007 Arizona Electric
Festival. Sean Plummer (of Aero-Model) owns the airplane.
independently. Although this is suitable for a
trainer or sport model, it is unacceptable for a
giant-scale aerobatic aircraft, because the
pilot cannot adjust the aileron differential
that is needed to make the airplane roll
axially.
I have written about aileron differential
before. As a recap, it is when the aileron
travel has more deflection in the “up”
direction or more deflection in the “down”
direction to make the airplane roll axially.
Models that are top-hinged primarily have
less deflection in the “up” direction, because
the aileron surface has more area on the top
of the aileron when compared to the bottom
of the aileron.
Advantages of Lithium Batteries: Weight
can also be saved with the battery chosen for
a given application. I use Li-Ion (or Poly)
batteries in all my giant-scale and F3A
models. A great amount of weight can be
saved on a giant-scale airplane.
A five-cell, 4200 mAh NiMH battery
weighs 12.6 ounces. A 5200 mAh Li-Ion
battery can weigh in at 6.8 ounces, which is
nearly half the weight! However, remember
to use a voltage regulator so that the voltage
going to the receiver is 6.0 (unless otherwise
specified by your radio manufacturer).
You have learned about the benefits that can
be obtained by choosing your electronic
equipment wisely, which ultimately results
in improving your aerobatic aircraft’s flight
performance.
By taking full advantage of your
computer radio’s mixing capabilities, the
need for servo synchronizers can be
eliminated (depending on the airframe and
the amount of servos that are needed
compared to the number of channels the
receiver being used contains). That will
result in a lighter overall airframe.
Since summer is finally approaching, get
back to the flightline and keep practicing!
Until next time, fly hard! MA
Sources:
JR
(800) 338-4639
www.jrradios.com
Futaba
(217) 398-8970
www.futaba-rc.com
Hitec RCD USA
(858) 748-6948
www.hitecrcd.com
Edition: Model Aviation - 2008/08
Page Numbers: 143,144
Edition: Model Aviation - 2008/08
Page Numbers: 143,144
Equipment weight savings greatly affects flight performance
August 2008 143
[[email protected]]
Radio Control Scale Aerobatics John Glezellis
to take full advantage of a given radio system
and the mixing capabilities it offers.
By using a 14-channel receiver (and the
14MZ radio system), I was able to mix all
four aileron servos so that no servo
synchronizers were needed. The same was
done for the elevator servos. (One channel
was the “master” elevator channel and one
channel was the “slave” elevator channel.)
Using a computer radio’s mixing
capabilities is important when it comes to
trimming your aircraft. Let’s look at the basic,
one-servo-per-aileron configuration.
I often see modelers use a “Y harness” to
make two servos work together for a given
function. However, if a Y harness is used, a
modeler cannot adjust each servo
are required). Let’s take a look at the weight
savings.
By reducing the elevator servos to only
one per half, a total weight of 14.4 ounces per
stabilizer half was obtained (compared to the
original weight of 18.2 ounces). A total
weight savings of 4.2 ounces was reduced per
stabilizer half, which results in a total savings
of 8.4 ounces.
The aircraft’s flight characteristics change
quite a bit when this amount of weight is
taken out—especially when it is taken out of
the tail.
Using Your Computer Radio Wisely: Today,
it is common to see many fliers use a ninechannel
or more radio system. It is important
LAST TIME, I wrote about the benefits of
using both Flight Modes and Flight
Conditions. This month we will look at a few
different ways in which a person can improve
his or her aircraft’s performance.
When I built my 38% Great Planes Extra
330S, I used one servo synchronizer per
aileron, one servo synchronizer per elevator
half, and one servo synchronizer on the
rudder. This resulted in the use of five servo
synchronizers.
In addition, I used two servos per elevator
half (I used the Futaba S9155, which offers
192 ounce-inch at 6.0 volts). I used two ninechannel
receivers on the airplane for
redundancy.
However, I recently converted this aircraft
to 2.4 GHz and selected a 14-channel
receiver. Therefore, the need for servo
synchronizers diminished.
All in all, each servo synchronizer has a
total weight of approximately .46 ounce. That
may not seem like a lot, but it can have a great
impact on your model’s flight performance,
depending on its location within the aircraft.
A few additional ounces of weight on the
CG will not change how your model
transitions from upright to inverted flight. But
a few ounces in the tail will (because of the
greater moment from the tail to the CG point).
Servo Talk: When considering elevator
servos for your giant-scale aerobatic aircraft,
look at the servo’s torque at 6.0 volts. When
40% airplanes were first introduced, it was
common to use two servos per elevator half
(and it still is, in some circumstances),
because the servos did not have enough
output. Today, many manufacturers have
servos with more than 300 ounce-inch of
torque at 6.0 volts.
JR has the 8711 (that has a total of 403
ounce-inch at 6.0 volts), Futaba has the S9156
(that has a total of 340 ounce-inch at 6.0
volts), and Hobbico and Hitec offer the CS-
170 and the HS-5955 (that each offer 333.0
ounce-inch at 6.0 volts). By selecting the right
servo for a given application, you can reduce
the number of servos you employ for a given
control surface.
In the 38% Extra 330S, I went from using
two servos per half (that give a total of
roughly 192 ounce-inch of torque each) to
only one servo per elevator half (each giving
330 ounce-inch of torque).
Now, not only does the modeler save
weight by reducing the number of servos, but
he or she also reduces the number of servo
extensions and the number of servo
synchronizers that are needed. (Two servo
synchronizers were originally used; now none
When programming a new model on the
Futaba 14MZ, the end user can select
wing and tail type. Here, two channels are
being used for both ailerons (one for
“master” channel; one for “slave”
channel) as well as elevators.
By using one servo per elevator half, a
great amount of weight (approximately 8.4
ounces total) has been saved from the tail.
The author with the Hacker-powered Pitts Python he flew at the 2007 Arizona Electric
Festival. Sean Plummer (of Aero-Model) owns the airplane.
independently. Although this is suitable for a
trainer or sport model, it is unacceptable for a
giant-scale aerobatic aircraft, because the
pilot cannot adjust the aileron differential
that is needed to make the airplane roll
axially.
I have written about aileron differential
before. As a recap, it is when the aileron
travel has more deflection in the “up”
direction or more deflection in the “down”
direction to make the airplane roll axially.
Models that are top-hinged primarily have
less deflection in the “up” direction, because
the aileron surface has more area on the top
of the aileron when compared to the bottom
of the aileron.
Advantages of Lithium Batteries: Weight
can also be saved with the battery chosen for
a given application. I use Li-Ion (or Poly)
batteries in all my giant-scale and F3A
models. A great amount of weight can be
saved on a giant-scale airplane.
A five-cell, 4200 mAh NiMH battery
weighs 12.6 ounces. A 5200 mAh Li-Ion
battery can weigh in at 6.8 ounces, which is
nearly half the weight! However, remember
to use a voltage regulator so that the voltage
going to the receiver is 6.0 (unless otherwise
specified by your radio manufacturer).
You have learned about the benefits that can
be obtained by choosing your electronic
equipment wisely, which ultimately results
in improving your aerobatic aircraft’s flight
performance.
By taking full advantage of your
computer radio’s mixing capabilities, the
need for servo synchronizers can be
eliminated (depending on the airframe and
the amount of servos that are needed
compared to the number of channels the
receiver being used contains). That will
result in a lighter overall airframe.
Since summer is finally approaching, get
back to the flightline and keep practicing!
Until next time, fly hard! MA
Sources:
JR
(800) 338-4639
www.jrradios.com
Futaba
(217) 398-8970
www.futaba-rc.com
Hitec RCD USA
(858) 748-6948
www.hitecrcd.com
