138 MODEL AVIATION
THE QUALITY and timing of the
approach to landing will make the
difference between landing points and no
landing points. Many factors come into
play during the approach, including your
model setup, discipline to do a “set”
approach, and efficient use of flaps.
I have enlisted one of the top sailplane
pilots—Tom Keisling—to give us his
approach to approaches. I’ll include his
thoughts later.
The first thing I must cover is the model
setup. A good approach is not going to
happen if your model is not maintaining a
consistent glide slope. If your aircraft’s
flaps and elevator are not properly
coupled, a good glide slope is impossible.
Initial setup involves ensuring that the
flaps are mechanically consistent with
each other. To do this, the servo horns
must be at the same starting point, the
flap horns must be the same distance from
the hinge line, and the servos must be the
same distance from the hinge line. If all
these are the same, the pushrod lengths
should match.
With the radio on, let’s see if the flaps
track together. They should. I have
encountered circumstances in which the
servos do not travel at the same speed.
Now I match the servos before
installation.
At the bottom of the stick, are the
flaps at the same point? Do you have
close to 90°? (I don’t really care if I have
exactly 90° as long as I’m close.) If not,
adjust with subtrims. Go to half stick and
see if they are the same. Top stick to half
stick is the most important since most of
your approach will be done in this area.
All modern control systems have a
flap/elevator mix. Many have multiple
point curves that allow extreme finetuning
of the mix. For those who are new
to the competition six-function sailplanes,
down-elevator is added when flaps are
lowered to prevent the nose from
ballooning. This is a rather simplistic
explanation, but it will become clearer as
we progress.
The Futaba 14MZ system I fly has a
14-point curve available. I use five to
seven points for the flap/elevator mix. My
process involves setting the flap stick to
half travel and then adding an arbitrary
amount of down-elevator to the mix.
Many will copy the approximate
points from another model and use this as
a baseline. That works fine if the models
are close to the same. I like to start anew
[[email protected]]
Radio Control Soaring Darwin Barrie
The author tackles the subject of approaches to landing
Accomplished Soaring pilot Tom Keisling’s technique for landing approaches is shown.
He details the procedure in the text.
with a new model since it is not a huge
deal to set these up with the modern
systems.
I try to do all setup flights in the early
morning in calm conditions. Before
launching I put the mix screen up so I can
make adjustments in the elevator
compensation. The model is launched and
flown relatively high and at a point out in
front of me with a good profile view.
I lower the flap stick to half to see what
happens. Then I can adjust the elevator up
or down to get the glide slope I want.
When that is set I activate the flaps a
couple times to check the glide slope. I
move to the first point down from the top
of the stick and repeat the process. Then I
move to the next point.
I use half stick for the first point
because it is the easiest to find on the
transmitter, and it is a substantial amount
of flap. If anything bad occurs, I know I
can go to half stick and get the sailplane
slowed predictably. I repeat the process
for the lower half of the flap travel.
Once all points are set, I can fine-tune
them easily. The goal is to be able to move
the flap stick full travel and not have the
attitude of the model change—only the
airspeed. I can usually get close to a
functional mix in a flight or two.
Being a 3,000-plus-hour full-scale pilot, I
can attest to the fact that the quality of the
approach will have a direct effect on the
quality of the landing. This is drummed
into every student pilot from day one in
the training process. Success in soaring is
no different.
My technique for approaches can be
used for predictable, consistent results
every time. For the purposes of this
discussion we will be using a left-hand
approach.
I begin the approach by flying from left
to right, slightly in front of me and
approximately 100 feet in the air with 50
seconds remaining on the clock. At 40
09sig5.QXD 7/26/06 8:52 AM Page 138seconds I make a left turn to the downwind
leg. I fly this leg for 10 seconds.
I also begin to slow the model with
flaps and adjust as necessary to get a good
approach speed. You must experiment
with this with your specific model.
At 30 seconds I turn the base leg. I am
estimating that the sailplane is 25 feet in
the air at this point. Final is turned at 20
seconds. Depending on the wind
conditions, I will adjust the flaps to gauge
for the landing on time. The last 30 feet to
landing is flown low to the ground,
allowing the model to be guided to the
proper spot.
You will definitely have to play with
this system and adapt it to your model and
wind conditions. In downwind conditions
I will shorten the final leg to 15 seconds
or less. If the field is unfamiliar I will try
to get some practice in using this system
so I can get visual cues as well.
Following is Tom Keisling’s approach to
approaches.
“The key to landing accurately for
contests is to practice. To increase the
effectiveness of your practice sessions
you should try and exercise the following
suggestions.
“1) Set up an approach pattern. A good
pattern to start with is fly over your head
with approximately 30 seconds to go into
the wind. By doing this you can determine
the speed of your airplane and
appropriately adjust it.
“After you acquaint yourself with the
status of your model, do a 180° turn
downwind. The model should be offset
from the landing spot by approximately
100 feet. At roughly 20 seconds to go,
turn 90° toward the spot and fly straight.
With approximately 15 seconds to go, turn
final and shoot the landing.
“2) Learn how to use your flaps. A
proper approach will have subtle control
inputs (unless it is very turbulent). During
final you should probably not have much
more than 25° of flap if you managed your
energy properly during the downwind and
base leg. This will give you some
flexibility during final. You can use more
or less flap as necessary as you get closer
to the spot.
“3) I find it is best to fly straight up the
tape (good end toward you and bad end
downwind). You should be flying with
minimal airspeed at this point—just
enough to maintain positive control. If you
do it right, you should be approximately 2
feet off the ground at the bad end of the
tape. By flying straight up the tape, you
have a reference to where the model is
with respect to the good landing points
and the bad ones. It makes the need for
great depth perception less critical.“As you get closer to the mark, adjust
your model’s speed as necessary with the
flaps. Just before the mark,
simultaneously raise the flaps and pop
some down-elevator. If all went well,
your model should gently tap the 100 and
stay there. If you had too much speed, it
may pound the 100 and cause some
damage and/or bounce past. If you had
too little speed, the pop of down-elevator
may be ineffective and your model may
go over.”
The accompanying drawing
summarizes the preceding technique.
Remember that you have to be able to
land using a right- or left-hand pattern, so
practice both.
Of course there are variations on this
method. The key thing to remember is to
have a plan for your landing and not go
about it haphazardly.
Another practice I have found that
helps me is to glance down at the tape
periodically when I am performing the
approach pattern. When I do this, I
visualize what the landing will look like.
This mental picture helps put the model in
the right place when it gets close to the
tape.
Tom’s technique is a bit different, but
the concepts are the same. Use your
glider’s flaps and control your speed.
Thanks for the input, Tom.
Next time I will discuss several aspects
of the hand-launched sailplanes and their
benefits to making you an overall better thermal pilot.
Edition: Model Aviation - 2006/09
Page Numbers: 138,139
Edition: Model Aviation - 2006/09
Page Numbers: 138,139
138 MODEL AVIATION
THE QUALITY and timing of the
approach to landing will make the
difference between landing points and no
landing points. Many factors come into
play during the approach, including your
model setup, discipline to do a “set”
approach, and efficient use of flaps.
I have enlisted one of the top sailplane
pilots—Tom Keisling—to give us his
approach to approaches. I’ll include his
thoughts later.
The first thing I must cover is the model
setup. A good approach is not going to
happen if your model is not maintaining a
consistent glide slope. If your aircraft’s
flaps and elevator are not properly
coupled, a good glide slope is impossible.
Initial setup involves ensuring that the
flaps are mechanically consistent with
each other. To do this, the servo horns
must be at the same starting point, the
flap horns must be the same distance from
the hinge line, and the servos must be the
same distance from the hinge line. If all
these are the same, the pushrod lengths
should match.
With the radio on, let’s see if the flaps
track together. They should. I have
encountered circumstances in which the
servos do not travel at the same speed.
Now I match the servos before
installation.
At the bottom of the stick, are the
flaps at the same point? Do you have
close to 90°? (I don’t really care if I have
exactly 90° as long as I’m close.) If not,
adjust with subtrims. Go to half stick and
see if they are the same. Top stick to half
stick is the most important since most of
your approach will be done in this area.
All modern control systems have a
flap/elevator mix. Many have multiple
point curves that allow extreme finetuning
of the mix. For those who are new
to the competition six-function sailplanes,
down-elevator is added when flaps are
lowered to prevent the nose from
ballooning. This is a rather simplistic
explanation, but it will become clearer as
we progress.
The Futaba 14MZ system I fly has a
14-point curve available. I use five to
seven points for the flap/elevator mix. My
process involves setting the flap stick to
half travel and then adding an arbitrary
amount of down-elevator to the mix.
Many will copy the approximate
points from another model and use this as
a baseline. That works fine if the models
are close to the same. I like to start anew
[[email protected]]
Radio Control Soaring Darwin Barrie
The author tackles the subject of approaches to landing
Accomplished Soaring pilot Tom Keisling’s technique for landing approaches is shown.
He details the procedure in the text.
with a new model since it is not a huge
deal to set these up with the modern
systems.
I try to do all setup flights in the early
morning in calm conditions. Before
launching I put the mix screen up so I can
make adjustments in the elevator
compensation. The model is launched and
flown relatively high and at a point out in
front of me with a good profile view.
I lower the flap stick to half to see what
happens. Then I can adjust the elevator up
or down to get the glide slope I want.
When that is set I activate the flaps a
couple times to check the glide slope. I
move to the first point down from the top
of the stick and repeat the process. Then I
move to the next point.
I use half stick for the first point
because it is the easiest to find on the
transmitter, and it is a substantial amount
of flap. If anything bad occurs, I know I
can go to half stick and get the sailplane
slowed predictably. I repeat the process
for the lower half of the flap travel.
Once all points are set, I can fine-tune
them easily. The goal is to be able to move
the flap stick full travel and not have the
attitude of the model change—only the
airspeed. I can usually get close to a
functional mix in a flight or two.
Being a 3,000-plus-hour full-scale pilot, I
can attest to the fact that the quality of the
approach will have a direct effect on the
quality of the landing. This is drummed
into every student pilot from day one in
the training process. Success in soaring is
no different.
My technique for approaches can be
used for predictable, consistent results
every time. For the purposes of this
discussion we will be using a left-hand
approach.
I begin the approach by flying from left
to right, slightly in front of me and
approximately 100 feet in the air with 50
seconds remaining on the clock. At 40
09sig5.QXD 7/26/06 8:52 AM Page 138seconds I make a left turn to the downwind
leg. I fly this leg for 10 seconds.
I also begin to slow the model with
flaps and adjust as necessary to get a good
approach speed. You must experiment
with this with your specific model.
At 30 seconds I turn the base leg. I am
estimating that the sailplane is 25 feet in
the air at this point. Final is turned at 20
seconds. Depending on the wind
conditions, I will adjust the flaps to gauge
for the landing on time. The last 30 feet to
landing is flown low to the ground,
allowing the model to be guided to the
proper spot.
You will definitely have to play with
this system and adapt it to your model and
wind conditions. In downwind conditions
I will shorten the final leg to 15 seconds
or less. If the field is unfamiliar I will try
to get some practice in using this system
so I can get visual cues as well.
Following is Tom Keisling’s approach to
approaches.
“The key to landing accurately for
contests is to practice. To increase the
effectiveness of your practice sessions
you should try and exercise the following
suggestions.
“1) Set up an approach pattern. A good
pattern to start with is fly over your head
with approximately 30 seconds to go into
the wind. By doing this you can determine
the speed of your airplane and
appropriately adjust it.
“After you acquaint yourself with the
status of your model, do a 180° turn
downwind. The model should be offset
from the landing spot by approximately
100 feet. At roughly 20 seconds to go,
turn 90° toward the spot and fly straight.
With approximately 15 seconds to go, turn
final and shoot the landing.
“2) Learn how to use your flaps. A
proper approach will have subtle control
inputs (unless it is very turbulent). During
final you should probably not have much
more than 25° of flap if you managed your
energy properly during the downwind and
base leg. This will give you some
flexibility during final. You can use more
or less flap as necessary as you get closer
to the spot.
“3) I find it is best to fly straight up the
tape (good end toward you and bad end
downwind). You should be flying with
minimal airspeed at this point—just
enough to maintain positive control. If you
do it right, you should be approximately 2
feet off the ground at the bad end of the
tape. By flying straight up the tape, you
have a reference to where the model is
with respect to the good landing points
and the bad ones. It makes the need for
great depth perception less critical.“As you get closer to the mark, adjust
your model’s speed as necessary with the
flaps. Just before the mark,
simultaneously raise the flaps and pop
some down-elevator. If all went well,
your model should gently tap the 100 and
stay there. If you had too much speed, it
may pound the 100 and cause some
damage and/or bounce past. If you had
too little speed, the pop of down-elevator
may be ineffective and your model may
go over.”
The accompanying drawing
summarizes the preceding technique.
Remember that you have to be able to
land using a right- or left-hand pattern, so
practice both.
Of course there are variations on this
method. The key thing to remember is to
have a plan for your landing and not go
about it haphazardly.
Another practice I have found that
helps me is to glance down at the tape
periodically when I am performing the
approach pattern. When I do this, I
visualize what the landing will look like.
This mental picture helps put the model in
the right place when it gets close to the
tape.
Tom’s technique is a bit different, but
the concepts are the same. Use your
glider’s flaps and control your speed.
Thanks for the input, Tom.
Next time I will discuss several aspects
of the hand-launched sailplanes and their
benefits to making you an overall better thermal pilot.