Jim T. Graham | jgraham@Born to Fly rcgroups.com
DLG: It’s not your grandpa’s Sailplane!
I HAVE BECOME a huge fan of
Sailplanes, but not just any Sailplane. I am
all about the Discus Launch Glider (DLG).
I saw my first DLG flight at the Clover
Creek competition in between rounds and
then started noticing them hiding in trailers
of my favorite 3-D pilots. DLG is a
Sailplane that you throw discus-style.
Being a newbie at this form of RC has
been tons of fun and loaded with questions. I
thought it might be informative for me, as
well as you, if I asked a DLG expert some of
my newbie questions.
I had a long talk with DLG veteran
Bruce Davidson. Bruce is well-known in the
DLG circles and also hosts his own DLG
contest called—wait for it—The Bruce. If
you are into Sailplanes and DLG or if you
have been thinking about it, you might find
some answers to your questions in this
interview.
JG: When did you start flying and what kind
of airplane did you start out flying?
BD: I started flying in the 1970s. I started
out in Sailplanes. In the park near where I
grew up they flew Sailplanes. At that time
they were just balsa and MonoKote. You
have to guess what my first Sailplane was.
JG: A Gentle Lady?
BD: Exactly. That was a test to see if you
were a Sailplaner or not! I built it on an old
door in my mom and dad’s house. When I
got it done I went to the Louisville Area
Soaring Society. They still fly in that same
park. The person who taught me to fly was
Ed Wilson and I still see him out there.
I took a little bit of time off when I was in
the military. I flew some during that time and
that was the only time I flew power because
that was the only option. I picked Sailplanes
right back up when I got out.
JG: I got into DLG by watching a pilot at the
Clover Creek competition fly one. Do you
think DLG is gaining in popularity, and if so
why?
BD: It’s absolutely gaining in popularity and
that is evident by looking at the attendance in
the clubs. I originally flew hand-launched
gliders. Back then you were lucky to find a
contest here and there. There was a great big
one in California that is still in existence: the
International Hand Launch Glider Festival.
Switching over from the hand launch to
the discuss launch was what allowed it to
pick up steam. The javelin launch was a very
physical way to throw an airplane. That had
huge rewards for guys who were young and
athletic and put in the time. At that time I
was that guy; I’m not that guy now.
The advent of the discuss launch made it
more accessible to more pilots. That has
helped its gain in popularity as well as the
availability of models.
Kai Yang shows
the power and
technique
involved in
launching a
DLG. Frank
Dumas photo.
Right: Jeff Pfeifer prepares for a catch and
instant relaunch. Dumas photo.
Bruce Davidson is the
founder of the The Bruce
DLG competition and
farmer on the Thermal
Farm in Kentucky.
November 2011 89
11sig3.QXD_00MSTRPG.QXD 9/22/11 11:08 AM Page 89
JG: For our readers who don’t know, a
discuss-launched glider is a 9- to 11-ounce
Sailplane with an average wingspan limited
to 1.5 meters. The airplane is held by tabs on
the wingtip and rotated around the pilot by
hand before release. So it’s like throwing a
discus. What are your DLG launch tips?
BD: I usually try to take two steps when I
throw. It helps me orientate into the wind so I
know what direction I’m going. It also gives
me time to wind up. You have to think about
it like releasing a spring. What you want to
do is reach back and twist to coil that spring
up. I do that in the run-up.
JG: I try to keep the airplane as far behind
me as I can so I can get as much “fling” on it
as possible. Is that right?
BD: You want to keep it on toe. The longer
you’re in contact with the airplane, the longer
the arc is, and that means more time to
accelerate. That is where I build my speed.
The two things I think about are to reach
back as far as I can and to accelerate the
entire time.
You can’t just muscle it at the last
minute. It will make it yaw and put some
tough stresses on the airplane. You want it to
accelerate in a very fluid manner through the
entire process. Another key thing is to follow
through.
JG: I think of it like hitting a golf ball.
BD: Golf is a really good example. Your
power comes from the core; you line up,
accelerate, and follow through. There is a lot
of footwork that goes on that you should
never think about.
JG: Right before you release, it looks
like you’re keeping that back leg planted
as you spin around to release the
airplane, allowing your body to rotate.
BD: That would be the footwork part of
it that I recommend you never think
about (laughter). That’s good advice. I
would urge you not to think about your
feet.
JG: Does anyone spin around twice? I
try this occasionally.
BD: There are a bunch of people that
have tried that route before but there
doesn’t seem to be an advantage to it.
JG: If there is no one at my field I will
tend to wander around as I throw and fly
my airplane. Is that typical?
Left: The pilots from
the 2010 The Bruce
F3K competition.
And no, the miniature
donkeys were not
official competitors.
Left: Richard Swindells in the foreground
and Paul Anderson and Phil Barns
(background) are all launching at once.
Dumas photo.
A Sidewinder DLG Sailplane is hunting
for thermals. Dumas photo.
Nick Chitty released his
model to go sniff out
thermals. Dumas photo.
90 MODEL AVIATION
11sig3.QXD_00MSTRPG.QXD 9/22/11 11:08 AM Page 90
November 2011 91
BD: Most guys walk. Some guys don’t move
a bit. We all have a tendency to move toward
our airplane. The thing about flying
Sailplanes is you go where the lift is. In a
contest there are times when I will run to the
other side of the field instead of flying.
If I landed at one end of the field but on
the other side of the field where there was lift,
then it might be more efficient for me to run
across that field and launch into that thermal.
Sometimes it is better to run, sometimes it is
better to launch from where you are.
Wandering is perfectly acceptable. That is
why we usually have a caller. He will tell you
where the thermals are; he will tell you if you
are walking into traffic, etc.
JG: I have caught a few thermals since I have
started. I try not to scrub off speed by making
too many turns but I’m not sure what to do
when I feel as though I’m in lift. I’m afraid if
I make abrupt turns to get in the thermal I
will kill all of my momentum. What do you do
when you see the nose of the airplane go up?
BD: That’s a great question because you
really hit on what Sailplanes are about. It’s
about being efficient. Every time we move a
control surface, we cause drag and that makes
your airplane fall out of the sky faster.
Typically in that scenario if your nose
goes up you probably hit the thermal nose-on.
That is the easiest way to tell where the lift is.
When your Sailplane goes off level it tells
you something about what you flew through
and tells you what you need to do. So if your
nose goes up then your airplane is trying to
go up; but it’s a Sailplane and that’s not going
to happen.
The next thing that will happen is you’re
going to stall. You have to apply some downelevator
so you can keep flying nice and
level. I would fly through that thing. When
you get through it you will see your tail go
up. You airplane gets a little more lively and
it bobbles around and speeds up a little bit.
If you pay attention to the speed of your
airplane, you can tell when you get to the
other side of it. Then I would come back to it
and initiate a turn.
JG: What kind of turn would you make to get
back into it?
BD: That depends. If it’s really windy then I
would do a hard turn. If it’s a nice, calm day
then I would do an easy turn.
At this point I would know exactly where
the thermal is. I wouldn’t have to be in a
hurry to get to it. Now that I have already
flown through it, I have an image in my mind
where it is. You want to watch that fuselage
and keep it nice and level. If you are in lift
then you can leave it pointing up a little bit.
At this point it’s like having a motor on the
front.
JG: The thermal is always moving, so am I
using wind direction to tell me where it’s
going or where it’s going to be?
BD: As you do the turn, think about it in
quarters. I try to slice my turn into four
pieces of a pizza. I would ask myself is this
piece better or is another better. Every
quarter where it’s better you open up your
turn. This will allow you to follow that
thermal.
Also, ask that better-or-worse question
and open to the better quarter. That makes it
easier to read it and see it. It’s important to
watch for that feedback. Did it go faster?
Did it go down? Did I stall? If it gets faster
on one side then open your turn up to that
side. There is a lot of subtle information that
the airplane is giving you. All this will help
you follow the lift.
JG: The other day I was only 10 feet off the
ground and the Sailplane just started going
up. It went up and up to the point it was a
little scary!
BD: When you are coming in on an
approach and then, bang, you feel some lift
... those are the best. There is nothing better
than catching them low.
JG: I’m still looking for another one. I guess
that’s part of the draw. How low is low for
you?
BD: Oh, 10 feet off the ground maybe. You
know a lot of times when it’s that low you
can feel the thermal. So that’s another
challenge and a big step in flying contests.
You need to know where the lift is and
launch straight to it.
Guys at your stage will be like, “Yeah, I
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got a thermal and I’m taking this baby
out of here!” Then you get real far out,
but once you know how to fly a thermal
and know how to identify it, the fun part
is how many times you can get to the
same thermal. You try to get to the best
part, the part we call the sweet spot.
There is a spot where all four sides
are going up just as well. You find that
speed mode, which is raising the TE up
on your ailerons. Now it’s going to fly
fast. You could come ripping home at 60
mph, grab a catch, and throw to the same
lift. This is what I practice a lot.
Sometimes it will get farther away than
you can get home if you don’t find it.
That’s a really fun thermal. We call it a
“Hero or a Zero.”
JG: I saw where you said it is better to
throw at the horizon instead of throwing
up to the sky. Tell me about that.
BD: Yes it is, if our airplane is properly
trimmed in speed mode. Usually a DLG
will have two or three settings that affect
the TE of your wing. In speed mode,
your ailerons rise up and fly faster. In
thermal mode, your TE is lowered and
you fly the slowest. In that speed mode,
coming off a throw it should fly nice and
straight and level. So we do a launch
preset.
Normally a launch preset is just a little bit
of up-elevator. It’s just enough to give us a
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11sig3.QXD_00MSTRPG.QXD 9/22/11 10:59 AM Page 91
92 MODEL AVIATION
AMA Academy of Model
Aeronautics
ARF Almost Ready to Fly
BEC Battery Eliminator Circuit
CA cyanoacrylate glue
CAD computer-aided design
cc cubic centimeter
CD contest director or
compact disc
CG center of gravity
CL Control Line
cm centimeter
cu. in. cubic inch
dBA DeciBels Adjusted (noise
power calculated in dB
[decibel])
DT dethermalizer
EAA Experimental Aircraft
Association
EPP (foam) expanded
polypropylene
ESC Electronic Speed Control
EPS expanded polystyrene foam
FAA Federal Aviation
Administration
FAI Fédération Aéronautique
Internationale
FCC Federal Communications
Commission
FF Free Flight
GHz gigahertz
ID inside diameter
Kv rpm/volt
kV kilovolt (1,000 volts)
LCD Liquid Crystal Display
LE leading edge
LED light-emitting diode
Li-Poly Lithium Polymer
mA milliamperes
MA Model Aviation
mAh milliampere-hours
MHz megahertz
mm millimeter
Nats AMA Nationals
nitro nitromethane
Ni-Cd Nickel Cadmium
NiMH Nickel Metal Hydride
OD outside diameter
RC Radio Control
rpm revolutions per minute
RTF Ready to Fly
SASE self-addressed, stamped
envelope
SIG Special Interest Group
TE trailing edge
Model Aviation’s
Frequently Used Abbreviations /Acronyms
quick rotation to roughly 45° and then we can
release that preset. A lot of guys put it on a
momentary switch. I have it on the switch
closest to my index finger. That allows me to
flip it on and flip it off.
You’re going to get more power if you can
do a flat rotation and throw straight at the
horizon. So you flip the preset switch, do your
spin release, and as soon it gets to the right
angle, you flip that switch off and finish the
climb and then push off over the top. So it’s
important to have a well-tuned launch preset.
JG: Can you DLG when it’s 90° at night and
104° in the daytime? Are there still thermals
out there?
BD: The thermals are really weak. When you
walk outside and see big clouds that are like
cotton candy, then you know that thermals
made those clouds and it’s going to be a good
day. The best thermal days are when we have
a big temperature difference from day to
night. So you want it to be cool at night and
warm during the days. Thermals are there
during the summer, but it’s much more
challenging because they are lighter and
dissolve quicker.
JG: Do you try to visualize the thermal in
your mind or are you working off feel?
BD: There are a whole lot of things going on.
A good learning tool is visualizing how the air
works. Air behaves like water. If there is a tree
line, you can visualize how the air hits that
and gets pushed up into the air and tumbles
over the top.
JG: Like a wave?
BD: Just like a wave. If a thermal comes
down this swirling air, it hits those trees and
gets thrown up into the sky. So that is a really
good visualization practice. When I encounter
a thermal, I always visualize it as a tornado.
That’s your most typical shape, but thermals
can also be blobby donuts as well.
That’s why catching them low is so tough.
They are smaller at the bottom. So when you
are really high it seems like you can just eat
up the sky and fly anywhere you want and not
come down. Up that high you have these great
big thermals. Visualization really does help.
JG: What kind of Sailplanes do you fly?
BD: I fly the Sirius and Polaris by Momentum
Models in Sweden. There are a bunch of great
models out there. I like the Sirius. It’s all
carbon fiber and really strong. It works for
me. I need a model that doesn’t break when I
throw it.
Once you get to the competition-level
Sailplanes, there is not a big difference in
performance. Sometimes a model might give
up lightness to fly better in strong winds.
Some might give up strong wind performance
to do better in light air. There are different
design directions because you can’t really
predict what conditions will be.
Most DLG Sailplanes are designed to do
well in all conditions. When the wind is high,
you can add more lead for ballast. Most
models weigh approximately 11 ounces, so if
I add 2½ ounces, that is a big percentage
increase in weight. It allows me to throw
harder and fly faster. The Sirius is a good allaround
airplane. They are all so close I can’t
strongly recommend one over another.
Get something that is available. By the
time you get a contest DLG Sailplane flying,
you’re going to have a $1,000 in it no matter
which one you buy. Your best bet for an
entry-level airplane is to find a used one. Most
of these guys who fly contests get a ding in
them here and there; they aren’t as clean as
they once were and they don’t want to fly a
contest with a beater. So you can pick it up
and get flying right now. The Blaster is up
there with the $900 models. It’s affordable
and available.
Really, it’s about how much you practice.
So just get something you can get up there
with. DLG is a pretty steep learning curve. So
if it’s already beat up you won’t be
emotionally attached to it.
JG: Is there anything you would like to say to
future DLG pilots?
BD: The best thing you can do is to fly with
someone else who is experienced. You’re
going to learn so much faster and get to that
enjoyment level so much faster if you can get
good instruction from someone who’s already
out there doing it.
Don’t be a fair-weather flier. In the
springtime you will go out there and the
weather is great with big puffy clouds and it is
“all-you-can-eat” thermals, but there is so
much satisfaction in a blustery day when it’s
overcast and gray, blowing 10 mph. You can
get out there and realize the air is just as active
on a crappy day when you would normally sit
on a couch. It’s awesome to go out on a bad
day and throw the airplane and get 3- and 4-
minute flights all day long. It’s like a great
day of fishing, you just keep catching them!
Living here on the thermal farm is a
beautiful thing. When I decide that it’s time to
fly, I pick my model up, pick my transmitter
up, and walk out. There is no other support
equipment needed. What’s really neat is DLG
pilots are passionate about what they do. They
love the challenge, they love the thermals, and
they like to think about when they first started
and all the things that they learned.
I think that you will find the DLG
community is fantastic. Everybody on the
field is really there to help. Everyone wants
you to succeed and find the joy that they find
in Soaring. MA
Sources:
The Bruce F3K
www.thebrucef3k.com
Momentum Model Technologies
www.momentum-mt.se
11sig3.QXD_00MSTRPG.QXD 9/22/11 10:59 AM Page 92
Edition: Model Aviation - 2011/11
Page Numbers: 89,90,91,92
Edition: Model Aviation - 2011/11
Page Numbers: 89,90,91,92
Jim T. Graham | jgraham@Born to Fly rcgroups.com
DLG: It’s not your grandpa’s Sailplane!
I HAVE BECOME a huge fan of
Sailplanes, but not just any Sailplane. I am
all about the Discus Launch Glider (DLG).
I saw my first DLG flight at the Clover
Creek competition in between rounds and
then started noticing them hiding in trailers
of my favorite 3-D pilots. DLG is a
Sailplane that you throw discus-style.
Being a newbie at this form of RC has
been tons of fun and loaded with questions. I
thought it might be informative for me, as
well as you, if I asked a DLG expert some of
my newbie questions.
I had a long talk with DLG veteran
Bruce Davidson. Bruce is well-known in the
DLG circles and also hosts his own DLG
contest called—wait for it—The Bruce. If
you are into Sailplanes and DLG or if you
have been thinking about it, you might find
some answers to your questions in this
interview.
JG: When did you start flying and what kind
of airplane did you start out flying?
BD: I started flying in the 1970s. I started
out in Sailplanes. In the park near where I
grew up they flew Sailplanes. At that time
they were just balsa and MonoKote. You
have to guess what my first Sailplane was.
JG: A Gentle Lady?
BD: Exactly. That was a test to see if you
were a Sailplaner or not! I built it on an old
door in my mom and dad’s house. When I
got it done I went to the Louisville Area
Soaring Society. They still fly in that same
park. The person who taught me to fly was
Ed Wilson and I still see him out there.
I took a little bit of time off when I was in
the military. I flew some during that time and
that was the only time I flew power because
that was the only option. I picked Sailplanes
right back up when I got out.
JG: I got into DLG by watching a pilot at the
Clover Creek competition fly one. Do you
think DLG is gaining in popularity, and if so
why?
BD: It’s absolutely gaining in popularity and
that is evident by looking at the attendance in
the clubs. I originally flew hand-launched
gliders. Back then you were lucky to find a
contest here and there. There was a great big
one in California that is still in existence: the
International Hand Launch Glider Festival.
Switching over from the hand launch to
the discuss launch was what allowed it to
pick up steam. The javelin launch was a very
physical way to throw an airplane. That had
huge rewards for guys who were young and
athletic and put in the time. At that time I
was that guy; I’m not that guy now.
The advent of the discuss launch made it
more accessible to more pilots. That has
helped its gain in popularity as well as the
availability of models.
Kai Yang shows
the power and
technique
involved in
launching a
DLG. Frank
Dumas photo.
Right: Jeff Pfeifer prepares for a catch and
instant relaunch. Dumas photo.
Bruce Davidson is the
founder of the The Bruce
DLG competition and
farmer on the Thermal
Farm in Kentucky.
November 2011 89
11sig3.QXD_00MSTRPG.QXD 9/22/11 11:08 AM Page 89
JG: For our readers who don’t know, a
discuss-launched glider is a 9- to 11-ounce
Sailplane with an average wingspan limited
to 1.5 meters. The airplane is held by tabs on
the wingtip and rotated around the pilot by
hand before release. So it’s like throwing a
discus. What are your DLG launch tips?
BD: I usually try to take two steps when I
throw. It helps me orientate into the wind so I
know what direction I’m going. It also gives
me time to wind up. You have to think about
it like releasing a spring. What you want to
do is reach back and twist to coil that spring
up. I do that in the run-up.
JG: I try to keep the airplane as far behind
me as I can so I can get as much “fling” on it
as possible. Is that right?
BD: You want to keep it on toe. The longer
you’re in contact with the airplane, the longer
the arc is, and that means more time to
accelerate. That is where I build my speed.
The two things I think about are to reach
back as far as I can and to accelerate the
entire time.
You can’t just muscle it at the last
minute. It will make it yaw and put some
tough stresses on the airplane. You want it to
accelerate in a very fluid manner through the
entire process. Another key thing is to follow
through.
JG: I think of it like hitting a golf ball.
BD: Golf is a really good example. Your
power comes from the core; you line up,
accelerate, and follow through. There is a lot
of footwork that goes on that you should
never think about.
JG: Right before you release, it looks
like you’re keeping that back leg planted
as you spin around to release the
airplane, allowing your body to rotate.
BD: That would be the footwork part of
it that I recommend you never think
about (laughter). That’s good advice. I
would urge you not to think about your
feet.
JG: Does anyone spin around twice? I
try this occasionally.
BD: There are a bunch of people that
have tried that route before but there
doesn’t seem to be an advantage to it.
JG: If there is no one at my field I will
tend to wander around as I throw and fly
my airplane. Is that typical?
Left: The pilots from
the 2010 The Bruce
F3K competition.
And no, the miniature
donkeys were not
official competitors.
Left: Richard Swindells in the foreground
and Paul Anderson and Phil Barns
(background) are all launching at once.
Dumas photo.
A Sidewinder DLG Sailplane is hunting
for thermals. Dumas photo.
Nick Chitty released his
model to go sniff out
thermals. Dumas photo.
90 MODEL AVIATION
11sig3.QXD_00MSTRPG.QXD 9/22/11 11:08 AM Page 90
November 2011 91
BD: Most guys walk. Some guys don’t move
a bit. We all have a tendency to move toward
our airplane. The thing about flying
Sailplanes is you go where the lift is. In a
contest there are times when I will run to the
other side of the field instead of flying.
If I landed at one end of the field but on
the other side of the field where there was lift,
then it might be more efficient for me to run
across that field and launch into that thermal.
Sometimes it is better to run, sometimes it is
better to launch from where you are.
Wandering is perfectly acceptable. That is
why we usually have a caller. He will tell you
where the thermals are; he will tell you if you
are walking into traffic, etc.
JG: I have caught a few thermals since I have
started. I try not to scrub off speed by making
too many turns but I’m not sure what to do
when I feel as though I’m in lift. I’m afraid if
I make abrupt turns to get in the thermal I
will kill all of my momentum. What do you do
when you see the nose of the airplane go up?
BD: That’s a great question because you
really hit on what Sailplanes are about. It’s
about being efficient. Every time we move a
control surface, we cause drag and that makes
your airplane fall out of the sky faster.
Typically in that scenario if your nose
goes up you probably hit the thermal nose-on.
That is the easiest way to tell where the lift is.
When your Sailplane goes off level it tells
you something about what you flew through
and tells you what you need to do. So if your
nose goes up then your airplane is trying to
go up; but it’s a Sailplane and that’s not going
to happen.
The next thing that will happen is you’re
going to stall. You have to apply some downelevator
so you can keep flying nice and
level. I would fly through that thing. When
you get through it you will see your tail go
up. You airplane gets a little more lively and
it bobbles around and speeds up a little bit.
If you pay attention to the speed of your
airplane, you can tell when you get to the
other side of it. Then I would come back to it
and initiate a turn.
JG: What kind of turn would you make to get
back into it?
BD: That depends. If it’s really windy then I
would do a hard turn. If it’s a nice, calm day
then I would do an easy turn.
At this point I would know exactly where
the thermal is. I wouldn’t have to be in a
hurry to get to it. Now that I have already
flown through it, I have an image in my mind
where it is. You want to watch that fuselage
and keep it nice and level. If you are in lift
then you can leave it pointing up a little bit.
At this point it’s like having a motor on the
front.
JG: The thermal is always moving, so am I
using wind direction to tell me where it’s
going or where it’s going to be?
BD: As you do the turn, think about it in
quarters. I try to slice my turn into four
pieces of a pizza. I would ask myself is this
piece better or is another better. Every
quarter where it’s better you open up your
turn. This will allow you to follow that
thermal.
Also, ask that better-or-worse question
and open to the better quarter. That makes it
easier to read it and see it. It’s important to
watch for that feedback. Did it go faster?
Did it go down? Did I stall? If it gets faster
on one side then open your turn up to that
side. There is a lot of subtle information that
the airplane is giving you. All this will help
you follow the lift.
JG: The other day I was only 10 feet off the
ground and the Sailplane just started going
up. It went up and up to the point it was a
little scary!
BD: When you are coming in on an
approach and then, bang, you feel some lift
... those are the best. There is nothing better
than catching them low.
JG: I’m still looking for another one. I guess
that’s part of the draw. How low is low for
you?
BD: Oh, 10 feet off the ground maybe. You
know a lot of times when it’s that low you
can feel the thermal. So that’s another
challenge and a big step in flying contests.
You need to know where the lift is and
launch straight to it.
Guys at your stage will be like, “Yeah, I
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got a thermal and I’m taking this baby
out of here!” Then you get real far out,
but once you know how to fly a thermal
and know how to identify it, the fun part
is how many times you can get to the
same thermal. You try to get to the best
part, the part we call the sweet spot.
There is a spot where all four sides
are going up just as well. You find that
speed mode, which is raising the TE up
on your ailerons. Now it’s going to fly
fast. You could come ripping home at 60
mph, grab a catch, and throw to the same
lift. This is what I practice a lot.
Sometimes it will get farther away than
you can get home if you don’t find it.
That’s a really fun thermal. We call it a
“Hero or a Zero.”
JG: I saw where you said it is better to
throw at the horizon instead of throwing
up to the sky. Tell me about that.
BD: Yes it is, if our airplane is properly
trimmed in speed mode. Usually a DLG
will have two or three settings that affect
the TE of your wing. In speed mode,
your ailerons rise up and fly faster. In
thermal mode, your TE is lowered and
you fly the slowest. In that speed mode,
coming off a throw it should fly nice and
straight and level. So we do a launch
preset.
Normally a launch preset is just a little bit
of up-elevator. It’s just enough to give us a
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11sig3.QXD_00MSTRPG.QXD 9/22/11 10:59 AM Page 91
92 MODEL AVIATION
AMA Academy of Model
Aeronautics
ARF Almost Ready to Fly
BEC Battery Eliminator Circuit
CA cyanoacrylate glue
CAD computer-aided design
cc cubic centimeter
CD contest director or
compact disc
CG center of gravity
CL Control Line
cm centimeter
cu. in. cubic inch
dBA DeciBels Adjusted (noise
power calculated in dB
[decibel])
DT dethermalizer
EAA Experimental Aircraft
Association
EPP (foam) expanded
polypropylene
ESC Electronic Speed Control
EPS expanded polystyrene foam
FAA Federal Aviation
Administration
FAI Fédération Aéronautique
Internationale
FCC Federal Communications
Commission
FF Free Flight
GHz gigahertz
ID inside diameter
Kv rpm/volt
kV kilovolt (1,000 volts)
LCD Liquid Crystal Display
LE leading edge
LED light-emitting diode
Li-Poly Lithium Polymer
mA milliamperes
MA Model Aviation
mAh milliampere-hours
MHz megahertz
mm millimeter
Nats AMA Nationals
nitro nitromethane
Ni-Cd Nickel Cadmium
NiMH Nickel Metal Hydride
OD outside diameter
RC Radio Control
rpm revolutions per minute
RTF Ready to Fly
SASE self-addressed, stamped
envelope
SIG Special Interest Group
TE trailing edge
Model Aviation’s
Frequently Used Abbreviations /Acronyms
quick rotation to roughly 45° and then we can
release that preset. A lot of guys put it on a
momentary switch. I have it on the switch
closest to my index finger. That allows me to
flip it on and flip it off.
You’re going to get more power if you can
do a flat rotation and throw straight at the
horizon. So you flip the preset switch, do your
spin release, and as soon it gets to the right
angle, you flip that switch off and finish the
climb and then push off over the top. So it’s
important to have a well-tuned launch preset.
JG: Can you DLG when it’s 90° at night and
104° in the daytime? Are there still thermals
out there?
BD: The thermals are really weak. When you
walk outside and see big clouds that are like
cotton candy, then you know that thermals
made those clouds and it’s going to be a good
day. The best thermal days are when we have
a big temperature difference from day to
night. So you want it to be cool at night and
warm during the days. Thermals are there
during the summer, but it’s much more
challenging because they are lighter and
dissolve quicker.
JG: Do you try to visualize the thermal in
your mind or are you working off feel?
BD: There are a whole lot of things going on.
A good learning tool is visualizing how the air
works. Air behaves like water. If there is a tree
line, you can visualize how the air hits that
and gets pushed up into the air and tumbles
over the top.
JG: Like a wave?
BD: Just like a wave. If a thermal comes
down this swirling air, it hits those trees and
gets thrown up into the sky. So that is a really
good visualization practice. When I encounter
a thermal, I always visualize it as a tornado.
That’s your most typical shape, but thermals
can also be blobby donuts as well.
That’s why catching them low is so tough.
They are smaller at the bottom. So when you
are really high it seems like you can just eat
up the sky and fly anywhere you want and not
come down. Up that high you have these great
big thermals. Visualization really does help.
JG: What kind of Sailplanes do you fly?
BD: I fly the Sirius and Polaris by Momentum
Models in Sweden. There are a bunch of great
models out there. I like the Sirius. It’s all
carbon fiber and really strong. It works for
me. I need a model that doesn’t break when I
throw it.
Once you get to the competition-level
Sailplanes, there is not a big difference in
performance. Sometimes a model might give
up lightness to fly better in strong winds.
Some might give up strong wind performance
to do better in light air. There are different
design directions because you can’t really
predict what conditions will be.
Most DLG Sailplanes are designed to do
well in all conditions. When the wind is high,
you can add more lead for ballast. Most
models weigh approximately 11 ounces, so if
I add 2½ ounces, that is a big percentage
increase in weight. It allows me to throw
harder and fly faster. The Sirius is a good allaround
airplane. They are all so close I can’t
strongly recommend one over another.
Get something that is available. By the
time you get a contest DLG Sailplane flying,
you’re going to have a $1,000 in it no matter
which one you buy. Your best bet for an
entry-level airplane is to find a used one. Most
of these guys who fly contests get a ding in
them here and there; they aren’t as clean as
they once were and they don’t want to fly a
contest with a beater. So you can pick it up
and get flying right now. The Blaster is up
there with the $900 models. It’s affordable
and available.
Really, it’s about how much you practice.
So just get something you can get up there
with. DLG is a pretty steep learning curve. So
if it’s already beat up you won’t be
emotionally attached to it.
JG: Is there anything you would like to say to
future DLG pilots?
BD: The best thing you can do is to fly with
someone else who is experienced. You’re
going to learn so much faster and get to that
enjoyment level so much faster if you can get
good instruction from someone who’s already
out there doing it.
Don’t be a fair-weather flier. In the
springtime you will go out there and the
weather is great with big puffy clouds and it is
“all-you-can-eat” thermals, but there is so
much satisfaction in a blustery day when it’s
overcast and gray, blowing 10 mph. You can
get out there and realize the air is just as active
on a crappy day when you would normally sit
on a couch. It’s awesome to go out on a bad
day and throw the airplane and get 3- and 4-
minute flights all day long. It’s like a great
day of fishing, you just keep catching them!
Living here on the thermal farm is a
beautiful thing. When I decide that it’s time to
fly, I pick my model up, pick my transmitter
up, and walk out. There is no other support
equipment needed. What’s really neat is DLG
pilots are passionate about what they do. They
love the challenge, they love the thermals, and
they like to think about when they first started
and all the things that they learned.
I think that you will find the DLG
community is fantastic. Everybody on the
field is really there to help. Everyone wants
you to succeed and find the joy that they find
in Soaring. MA
Sources:
The Bruce F3K
www.thebrucef3k.com
Momentum Model Technologies
www.momentum-mt.se
11sig3.QXD_00MSTRPG.QXD 9/22/11 10:59 AM Page 92
Edition: Model Aviation - 2011/11
Page Numbers: 89,90,91,92
Jim T. Graham | jgraham@Born to Fly rcgroups.com
DLG: It’s not your grandpa’s Sailplane!
I HAVE BECOME a huge fan of
Sailplanes, but not just any Sailplane. I am
all about the Discus Launch Glider (DLG).
I saw my first DLG flight at the Clover
Creek competition in between rounds and
then started noticing them hiding in trailers
of my favorite 3-D pilots. DLG is a
Sailplane that you throw discus-style.
Being a newbie at this form of RC has
been tons of fun and loaded with questions. I
thought it might be informative for me, as
well as you, if I asked a DLG expert some of
my newbie questions.
I had a long talk with DLG veteran
Bruce Davidson. Bruce is well-known in the
DLG circles and also hosts his own DLG
contest called—wait for it—The Bruce. If
you are into Sailplanes and DLG or if you
have been thinking about it, you might find
some answers to your questions in this
interview.
JG: When did you start flying and what kind
of airplane did you start out flying?
BD: I started flying in the 1970s. I started
out in Sailplanes. In the park near where I
grew up they flew Sailplanes. At that time
they were just balsa and MonoKote. You
have to guess what my first Sailplane was.
JG: A Gentle Lady?
BD: Exactly. That was a test to see if you
were a Sailplaner or not! I built it on an old
door in my mom and dad’s house. When I
got it done I went to the Louisville Area
Soaring Society. They still fly in that same
park. The person who taught me to fly was
Ed Wilson and I still see him out there.
I took a little bit of time off when I was in
the military. I flew some during that time and
that was the only time I flew power because
that was the only option. I picked Sailplanes
right back up when I got out.
JG: I got into DLG by watching a pilot at the
Clover Creek competition fly one. Do you
think DLG is gaining in popularity, and if so
why?
BD: It’s absolutely gaining in popularity and
that is evident by looking at the attendance in
the clubs. I originally flew hand-launched
gliders. Back then you were lucky to find a
contest here and there. There was a great big
one in California that is still in existence: the
International Hand Launch Glider Festival.
Switching over from the hand launch to
the discuss launch was what allowed it to
pick up steam. The javelin launch was a very
physical way to throw an airplane. That had
huge rewards for guys who were young and
athletic and put in the time. At that time I
was that guy; I’m not that guy now.
The advent of the discuss launch made it
more accessible to more pilots. That has
helped its gain in popularity as well as the
availability of models.
Kai Yang shows
the power and
technique
involved in
launching a
DLG. Frank
Dumas photo.
Right: Jeff Pfeifer prepares for a catch and
instant relaunch. Dumas photo.
Bruce Davidson is the
founder of the The Bruce
DLG competition and
farmer on the Thermal
Farm in Kentucky.
November 2011 89
11sig3.QXD_00MSTRPG.QXD 9/22/11 11:08 AM Page 89
JG: For our readers who don’t know, a
discuss-launched glider is a 9- to 11-ounce
Sailplane with an average wingspan limited
to 1.5 meters. The airplane is held by tabs on
the wingtip and rotated around the pilot by
hand before release. So it’s like throwing a
discus. What are your DLG launch tips?
BD: I usually try to take two steps when I
throw. It helps me orientate into the wind so I
know what direction I’m going. It also gives
me time to wind up. You have to think about
it like releasing a spring. What you want to
do is reach back and twist to coil that spring
up. I do that in the run-up.
JG: I try to keep the airplane as far behind
me as I can so I can get as much “fling” on it
as possible. Is that right?
BD: You want to keep it on toe. The longer
you’re in contact with the airplane, the longer
the arc is, and that means more time to
accelerate. That is where I build my speed.
The two things I think about are to reach
back as far as I can and to accelerate the
entire time.
You can’t just muscle it at the last
minute. It will make it yaw and put some
tough stresses on the airplane. You want it to
accelerate in a very fluid manner through the
entire process. Another key thing is to follow
through.
JG: I think of it like hitting a golf ball.
BD: Golf is a really good example. Your
power comes from the core; you line up,
accelerate, and follow through. There is a lot
of footwork that goes on that you should
never think about.
JG: Right before you release, it looks
like you’re keeping that back leg planted
as you spin around to release the
airplane, allowing your body to rotate.
BD: That would be the footwork part of
it that I recommend you never think
about (laughter). That’s good advice. I
would urge you not to think about your
feet.
JG: Does anyone spin around twice? I
try this occasionally.
BD: There are a bunch of people that
have tried that route before but there
doesn’t seem to be an advantage to it.
JG: If there is no one at my field I will
tend to wander around as I throw and fly
my airplane. Is that typical?
Left: The pilots from
the 2010 The Bruce
F3K competition.
And no, the miniature
donkeys were not
official competitors.
Left: Richard Swindells in the foreground
and Paul Anderson and Phil Barns
(background) are all launching at once.
Dumas photo.
A Sidewinder DLG Sailplane is hunting
for thermals. Dumas photo.
Nick Chitty released his
model to go sniff out
thermals. Dumas photo.
90 MODEL AVIATION
11sig3.QXD_00MSTRPG.QXD 9/22/11 11:08 AM Page 90
November 2011 91
BD: Most guys walk. Some guys don’t move
a bit. We all have a tendency to move toward
our airplane. The thing about flying
Sailplanes is you go where the lift is. In a
contest there are times when I will run to the
other side of the field instead of flying.
If I landed at one end of the field but on
the other side of the field where there was lift,
then it might be more efficient for me to run
across that field and launch into that thermal.
Sometimes it is better to run, sometimes it is
better to launch from where you are.
Wandering is perfectly acceptable. That is
why we usually have a caller. He will tell you
where the thermals are; he will tell you if you
are walking into traffic, etc.
JG: I have caught a few thermals since I have
started. I try not to scrub off speed by making
too many turns but I’m not sure what to do
when I feel as though I’m in lift. I’m afraid if
I make abrupt turns to get in the thermal I
will kill all of my momentum. What do you do
when you see the nose of the airplane go up?
BD: That’s a great question because you
really hit on what Sailplanes are about. It’s
about being efficient. Every time we move a
control surface, we cause drag and that makes
your airplane fall out of the sky faster.
Typically in that scenario if your nose
goes up you probably hit the thermal nose-on.
That is the easiest way to tell where the lift is.
When your Sailplane goes off level it tells
you something about what you flew through
and tells you what you need to do. So if your
nose goes up then your airplane is trying to
go up; but it’s a Sailplane and that’s not going
to happen.
The next thing that will happen is you’re
going to stall. You have to apply some downelevator
so you can keep flying nice and
level. I would fly through that thing. When
you get through it you will see your tail go
up. You airplane gets a little more lively and
it bobbles around and speeds up a little bit.
If you pay attention to the speed of your
airplane, you can tell when you get to the
other side of it. Then I would come back to it
and initiate a turn.
JG: What kind of turn would you make to get
back into it?
BD: That depends. If it’s really windy then I
would do a hard turn. If it’s a nice, calm day
then I would do an easy turn.
At this point I would know exactly where
the thermal is. I wouldn’t have to be in a
hurry to get to it. Now that I have already
flown through it, I have an image in my mind
where it is. You want to watch that fuselage
and keep it nice and level. If you are in lift
then you can leave it pointing up a little bit.
At this point it’s like having a motor on the
front.
JG: The thermal is always moving, so am I
using wind direction to tell me where it’s
going or where it’s going to be?
BD: As you do the turn, think about it in
quarters. I try to slice my turn into four
pieces of a pizza. I would ask myself is this
piece better or is another better. Every
quarter where it’s better you open up your
turn. This will allow you to follow that
thermal.
Also, ask that better-or-worse question
and open to the better quarter. That makes it
easier to read it and see it. It’s important to
watch for that feedback. Did it go faster?
Did it go down? Did I stall? If it gets faster
on one side then open your turn up to that
side. There is a lot of subtle information that
the airplane is giving you. All this will help
you follow the lift.
JG: The other day I was only 10 feet off the
ground and the Sailplane just started going
up. It went up and up to the point it was a
little scary!
BD: When you are coming in on an
approach and then, bang, you feel some lift
... those are the best. There is nothing better
than catching them low.
JG: I’m still looking for another one. I guess
that’s part of the draw. How low is low for
you?
BD: Oh, 10 feet off the ground maybe. You
know a lot of times when it’s that low you
can feel the thermal. So that’s another
challenge and a big step in flying contests.
You need to know where the lift is and
launch straight to it.
Guys at your stage will be like, “Yeah, I
!"#$$%&'
(')*+,-'
.+/01'2$+0
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1-800-966-3458 Made in USA
© 2011 Gorilla Glue Company
got a thermal and I’m taking this baby
out of here!” Then you get real far out,
but once you know how to fly a thermal
and know how to identify it, the fun part
is how many times you can get to the
same thermal. You try to get to the best
part, the part we call the sweet spot.
There is a spot where all four sides
are going up just as well. You find that
speed mode, which is raising the TE up
on your ailerons. Now it’s going to fly
fast. You could come ripping home at 60
mph, grab a catch, and throw to the same
lift. This is what I practice a lot.
Sometimes it will get farther away than
you can get home if you don’t find it.
That’s a really fun thermal. We call it a
“Hero or a Zero.”
JG: I saw where you said it is better to
throw at the horizon instead of throwing
up to the sky. Tell me about that.
BD: Yes it is, if our airplane is properly
trimmed in speed mode. Usually a DLG
will have two or three settings that affect
the TE of your wing. In speed mode,
your ailerons rise up and fly faster. In
thermal mode, your TE is lowered and
you fly the slowest. In that speed mode,
coming off a throw it should fly nice and
straight and level. So we do a launch
preset.
Normally a launch preset is just a little bit
of up-elevator. It’s just enough to give us a
The Source for Lightweight
Materials
www.acpsales.com
We Manufacture:
Composite Rods up to 1”dia. and
96” in length
Composite Tubes up to 3” dia. and 96” in length
Small Quanities-No Minimum Order Required-Fast Shipping
Composite Tubes & Rods
Carbon, Kevlar
®, & Fiberglass Fabrics
Laminates & Panels
Epoxy Resins Core Materials
Foam Cutting Equipment
f
rbon, Fibergl
www.Composite Laminates & Panels up to 5’ x 10’
Formed Composite Structures
Equip
d Vacuum Bagging Systems & Supplies
11sig3.QXD_00MSTRPG.QXD 9/22/11 10:59 AM Page 91
92 MODEL AVIATION
AMA Academy of Model
Aeronautics
ARF Almost Ready to Fly
BEC Battery Eliminator Circuit
CA cyanoacrylate glue
CAD computer-aided design
cc cubic centimeter
CD contest director or
compact disc
CG center of gravity
CL Control Line
cm centimeter
cu. in. cubic inch
dBA DeciBels Adjusted (noise
power calculated in dB
[decibel])
DT dethermalizer
EAA Experimental Aircraft
Association
EPP (foam) expanded
polypropylene
ESC Electronic Speed Control
EPS expanded polystyrene foam
FAA Federal Aviation
Administration
FAI Fédération Aéronautique
Internationale
FCC Federal Communications
Commission
FF Free Flight
GHz gigahertz
ID inside diameter
Kv rpm/volt
kV kilovolt (1,000 volts)
LCD Liquid Crystal Display
LE leading edge
LED light-emitting diode
Li-Poly Lithium Polymer
mA milliamperes
MA Model Aviation
mAh milliampere-hours
MHz megahertz
mm millimeter
Nats AMA Nationals
nitro nitromethane
Ni-Cd Nickel Cadmium
NiMH Nickel Metal Hydride
OD outside diameter
RC Radio Control
rpm revolutions per minute
RTF Ready to Fly
SASE self-addressed, stamped
envelope
SIG Special Interest Group
TE trailing edge
Model Aviation’s
Frequently Used Abbreviations /Acronyms
quick rotation to roughly 45° and then we can
release that preset. A lot of guys put it on a
momentary switch. I have it on the switch
closest to my index finger. That allows me to
flip it on and flip it off.
You’re going to get more power if you can
do a flat rotation and throw straight at the
horizon. So you flip the preset switch, do your
spin release, and as soon it gets to the right
angle, you flip that switch off and finish the
climb and then push off over the top. So it’s
important to have a well-tuned launch preset.
JG: Can you DLG when it’s 90° at night and
104° in the daytime? Are there still thermals
out there?
BD: The thermals are really weak. When you
walk outside and see big clouds that are like
cotton candy, then you know that thermals
made those clouds and it’s going to be a good
day. The best thermal days are when we have
a big temperature difference from day to
night. So you want it to be cool at night and
warm during the days. Thermals are there
during the summer, but it’s much more
challenging because they are lighter and
dissolve quicker.
JG: Do you try to visualize the thermal in
your mind or are you working off feel?
BD: There are a whole lot of things going on.
A good learning tool is visualizing how the air
works. Air behaves like water. If there is a tree
line, you can visualize how the air hits that
and gets pushed up into the air and tumbles
over the top.
JG: Like a wave?
BD: Just like a wave. If a thermal comes
down this swirling air, it hits those trees and
gets thrown up into the sky. So that is a really
good visualization practice. When I encounter
a thermal, I always visualize it as a tornado.
That’s your most typical shape, but thermals
can also be blobby donuts as well.
That’s why catching them low is so tough.
They are smaller at the bottom. So when you
are really high it seems like you can just eat
up the sky and fly anywhere you want and not
come down. Up that high you have these great
big thermals. Visualization really does help.
JG: What kind of Sailplanes do you fly?
BD: I fly the Sirius and Polaris by Momentum
Models in Sweden. There are a bunch of great
models out there. I like the Sirius. It’s all
carbon fiber and really strong. It works for
me. I need a model that doesn’t break when I
throw it.
Once you get to the competition-level
Sailplanes, there is not a big difference in
performance. Sometimes a model might give
up lightness to fly better in strong winds.
Some might give up strong wind performance
to do better in light air. There are different
design directions because you can’t really
predict what conditions will be.
Most DLG Sailplanes are designed to do
well in all conditions. When the wind is high,
you can add more lead for ballast. Most
models weigh approximately 11 ounces, so if
I add 2½ ounces, that is a big percentage
increase in weight. It allows me to throw
harder and fly faster. The Sirius is a good allaround
airplane. They are all so close I can’t
strongly recommend one over another.
Get something that is available. By the
time you get a contest DLG Sailplane flying,
you’re going to have a $1,000 in it no matter
which one you buy. Your best bet for an
entry-level airplane is to find a used one. Most
of these guys who fly contests get a ding in
them here and there; they aren’t as clean as
they once were and they don’t want to fly a
contest with a beater. So you can pick it up
and get flying right now. The Blaster is up
there with the $900 models. It’s affordable
and available.
Really, it’s about how much you practice.
So just get something you can get up there
with. DLG is a pretty steep learning curve. So
if it’s already beat up you won’t be
emotionally attached to it.
JG: Is there anything you would like to say to
future DLG pilots?
BD: The best thing you can do is to fly with
someone else who is experienced. You’re
going to learn so much faster and get to that
enjoyment level so much faster if you can get
good instruction from someone who’s already
out there doing it.
Don’t be a fair-weather flier. In the
springtime you will go out there and the
weather is great with big puffy clouds and it is
“all-you-can-eat” thermals, but there is so
much satisfaction in a blustery day when it’s
overcast and gray, blowing 10 mph. You can
get out there and realize the air is just as active
on a crappy day when you would normally sit
on a couch. It’s awesome to go out on a bad
day and throw the airplane and get 3- and 4-
minute flights all day long. It’s like a great
day of fishing, you just keep catching them!
Living here on the thermal farm is a
beautiful thing. When I decide that it’s time to
fly, I pick my model up, pick my transmitter
up, and walk out. There is no other support
equipment needed. What’s really neat is DLG
pilots are passionate about what they do. They
love the challenge, they love the thermals, and
they like to think about when they first started
and all the things that they learned.
I think that you will find the DLG
community is fantastic. Everybody on the
field is really there to help. Everyone wants
you to succeed and find the joy that they find
in Soaring. MA
Sources:
The Bruce F3K
www.thebrucef3k.com
Momentum Model Technologies
www.momentum-mt.se
11sig3.QXD_00MSTRPG.QXD 9/22/11 10:59 AM Page 92
Edition: Model Aviation - 2011/11
Page Numbers: 89,90,91,92
Jim T. Graham | jgraham@Born to Fly rcgroups.com
DLG: It’s not your grandpa’s Sailplane!
I HAVE BECOME a huge fan of
Sailplanes, but not just any Sailplane. I am
all about the Discus Launch Glider (DLG).
I saw my first DLG flight at the Clover
Creek competition in between rounds and
then started noticing them hiding in trailers
of my favorite 3-D pilots. DLG is a
Sailplane that you throw discus-style.
Being a newbie at this form of RC has
been tons of fun and loaded with questions. I
thought it might be informative for me, as
well as you, if I asked a DLG expert some of
my newbie questions.
I had a long talk with DLG veteran
Bruce Davidson. Bruce is well-known in the
DLG circles and also hosts his own DLG
contest called—wait for it—The Bruce. If
you are into Sailplanes and DLG or if you
have been thinking about it, you might find
some answers to your questions in this
interview.
JG: When did you start flying and what kind
of airplane did you start out flying?
BD: I started flying in the 1970s. I started
out in Sailplanes. In the park near where I
grew up they flew Sailplanes. At that time
they were just balsa and MonoKote. You
have to guess what my first Sailplane was.
JG: A Gentle Lady?
BD: Exactly. That was a test to see if you
were a Sailplaner or not! I built it on an old
door in my mom and dad’s house. When I
got it done I went to the Louisville Area
Soaring Society. They still fly in that same
park. The person who taught me to fly was
Ed Wilson and I still see him out there.
I took a little bit of time off when I was in
the military. I flew some during that time and
that was the only time I flew power because
that was the only option. I picked Sailplanes
right back up when I got out.
JG: I got into DLG by watching a pilot at the
Clover Creek competition fly one. Do you
think DLG is gaining in popularity, and if so
why?
BD: It’s absolutely gaining in popularity and
that is evident by looking at the attendance in
the clubs. I originally flew hand-launched
gliders. Back then you were lucky to find a
contest here and there. There was a great big
one in California that is still in existence: the
International Hand Launch Glider Festival.
Switching over from the hand launch to
the discuss launch was what allowed it to
pick up steam. The javelin launch was a very
physical way to throw an airplane. That had
huge rewards for guys who were young and
athletic and put in the time. At that time I
was that guy; I’m not that guy now.
The advent of the discuss launch made it
more accessible to more pilots. That has
helped its gain in popularity as well as the
availability of models.
Kai Yang shows
the power and
technique
involved in
launching a
DLG. Frank
Dumas photo.
Right: Jeff Pfeifer prepares for a catch and
instant relaunch. Dumas photo.
Bruce Davidson is the
founder of the The Bruce
DLG competition and
farmer on the Thermal
Farm in Kentucky.
November 2011 89
11sig3.QXD_00MSTRPG.QXD 9/22/11 11:08 AM Page 89
JG: For our readers who don’t know, a
discuss-launched glider is a 9- to 11-ounce
Sailplane with an average wingspan limited
to 1.5 meters. The airplane is held by tabs on
the wingtip and rotated around the pilot by
hand before release. So it’s like throwing a
discus. What are your DLG launch tips?
BD: I usually try to take two steps when I
throw. It helps me orientate into the wind so I
know what direction I’m going. It also gives
me time to wind up. You have to think about
it like releasing a spring. What you want to
do is reach back and twist to coil that spring
up. I do that in the run-up.
JG: I try to keep the airplane as far behind
me as I can so I can get as much “fling” on it
as possible. Is that right?
BD: You want to keep it on toe. The longer
you’re in contact with the airplane, the longer
the arc is, and that means more time to
accelerate. That is where I build my speed.
The two things I think about are to reach
back as far as I can and to accelerate the
entire time.
You can’t just muscle it at the last
minute. It will make it yaw and put some
tough stresses on the airplane. You want it to
accelerate in a very fluid manner through the
entire process. Another key thing is to follow
through.
JG: I think of it like hitting a golf ball.
BD: Golf is a really good example. Your
power comes from the core; you line up,
accelerate, and follow through. There is a lot
of footwork that goes on that you should
never think about.
JG: Right before you release, it looks
like you’re keeping that back leg planted
as you spin around to release the
airplane, allowing your body to rotate.
BD: That would be the footwork part of
it that I recommend you never think
about (laughter). That’s good advice. I
would urge you not to think about your
feet.
JG: Does anyone spin around twice? I
try this occasionally.
BD: There are a bunch of people that
have tried that route before but there
doesn’t seem to be an advantage to it.
JG: If there is no one at my field I will
tend to wander around as I throw and fly
my airplane. Is that typical?
Left: The pilots from
the 2010 The Bruce
F3K competition.
And no, the miniature
donkeys were not
official competitors.
Left: Richard Swindells in the foreground
and Paul Anderson and Phil Barns
(background) are all launching at once.
Dumas photo.
A Sidewinder DLG Sailplane is hunting
for thermals. Dumas photo.
Nick Chitty released his
model to go sniff out
thermals. Dumas photo.
90 MODEL AVIATION
11sig3.QXD_00MSTRPG.QXD 9/22/11 11:08 AM Page 90
November 2011 91
BD: Most guys walk. Some guys don’t move
a bit. We all have a tendency to move toward
our airplane. The thing about flying
Sailplanes is you go where the lift is. In a
contest there are times when I will run to the
other side of the field instead of flying.
If I landed at one end of the field but on
the other side of the field where there was lift,
then it might be more efficient for me to run
across that field and launch into that thermal.
Sometimes it is better to run, sometimes it is
better to launch from where you are.
Wandering is perfectly acceptable. That is
why we usually have a caller. He will tell you
where the thermals are; he will tell you if you
are walking into traffic, etc.
JG: I have caught a few thermals since I have
started. I try not to scrub off speed by making
too many turns but I’m not sure what to do
when I feel as though I’m in lift. I’m afraid if
I make abrupt turns to get in the thermal I
will kill all of my momentum. What do you do
when you see the nose of the airplane go up?
BD: That’s a great question because you
really hit on what Sailplanes are about. It’s
about being efficient. Every time we move a
control surface, we cause drag and that makes
your airplane fall out of the sky faster.
Typically in that scenario if your nose
goes up you probably hit the thermal nose-on.
That is the easiest way to tell where the lift is.
When your Sailplane goes off level it tells
you something about what you flew through
and tells you what you need to do. So if your
nose goes up then your airplane is trying to
go up; but it’s a Sailplane and that’s not going
to happen.
The next thing that will happen is you’re
going to stall. You have to apply some downelevator
so you can keep flying nice and
level. I would fly through that thing. When
you get through it you will see your tail go
up. You airplane gets a little more lively and
it bobbles around and speeds up a little bit.
If you pay attention to the speed of your
airplane, you can tell when you get to the
other side of it. Then I would come back to it
and initiate a turn.
JG: What kind of turn would you make to get
back into it?
BD: That depends. If it’s really windy then I
would do a hard turn. If it’s a nice, calm day
then I would do an easy turn.
At this point I would know exactly where
the thermal is. I wouldn’t have to be in a
hurry to get to it. Now that I have already
flown through it, I have an image in my mind
where it is. You want to watch that fuselage
and keep it nice and level. If you are in lift
then you can leave it pointing up a little bit.
At this point it’s like having a motor on the
front.
JG: The thermal is always moving, so am I
using wind direction to tell me where it’s
going or where it’s going to be?
BD: As you do the turn, think about it in
quarters. I try to slice my turn into four
pieces of a pizza. I would ask myself is this
piece better or is another better. Every
quarter where it’s better you open up your
turn. This will allow you to follow that
thermal.
Also, ask that better-or-worse question
and open to the better quarter. That makes it
easier to read it and see it. It’s important to
watch for that feedback. Did it go faster?
Did it go down? Did I stall? If it gets faster
on one side then open your turn up to that
side. There is a lot of subtle information that
the airplane is giving you. All this will help
you follow the lift.
JG: The other day I was only 10 feet off the
ground and the Sailplane just started going
up. It went up and up to the point it was a
little scary!
BD: When you are coming in on an
approach and then, bang, you feel some lift
... those are the best. There is nothing better
than catching them low.
JG: I’m still looking for another one. I guess
that’s part of the draw. How low is low for
you?
BD: Oh, 10 feet off the ground maybe. You
know a lot of times when it’s that low you
can feel the thermal. So that’s another
challenge and a big step in flying contests.
You need to know where the lift is and
launch straight to it.
Guys at your stage will be like, “Yeah, I
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got a thermal and I’m taking this baby
out of here!” Then you get real far out,
but once you know how to fly a thermal
and know how to identify it, the fun part
is how many times you can get to the
same thermal. You try to get to the best
part, the part we call the sweet spot.
There is a spot where all four sides
are going up just as well. You find that
speed mode, which is raising the TE up
on your ailerons. Now it’s going to fly
fast. You could come ripping home at 60
mph, grab a catch, and throw to the same
lift. This is what I practice a lot.
Sometimes it will get farther away than
you can get home if you don’t find it.
That’s a really fun thermal. We call it a
“Hero or a Zero.”
JG: I saw where you said it is better to
throw at the horizon instead of throwing
up to the sky. Tell me about that.
BD: Yes it is, if our airplane is properly
trimmed in speed mode. Usually a DLG
will have two or three settings that affect
the TE of your wing. In speed mode,
your ailerons rise up and fly faster. In
thermal mode, your TE is lowered and
you fly the slowest. In that speed mode,
coming off a throw it should fly nice and
straight and level. So we do a launch
preset.
Normally a launch preset is just a little bit
of up-elevator. It’s just enough to give us a
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11sig3.QXD_00MSTRPG.QXD 9/22/11 10:59 AM Page 91
92 MODEL AVIATION
AMA Academy of Model
Aeronautics
ARF Almost Ready to Fly
BEC Battery Eliminator Circuit
CA cyanoacrylate glue
CAD computer-aided design
cc cubic centimeter
CD contest director or
compact disc
CG center of gravity
CL Control Line
cm centimeter
cu. in. cubic inch
dBA DeciBels Adjusted (noise
power calculated in dB
[decibel])
DT dethermalizer
EAA Experimental Aircraft
Association
EPP (foam) expanded
polypropylene
ESC Electronic Speed Control
EPS expanded polystyrene foam
FAA Federal Aviation
Administration
FAI Fédération Aéronautique
Internationale
FCC Federal Communications
Commission
FF Free Flight
GHz gigahertz
ID inside diameter
Kv rpm/volt
kV kilovolt (1,000 volts)
LCD Liquid Crystal Display
LE leading edge
LED light-emitting diode
Li-Poly Lithium Polymer
mA milliamperes
MA Model Aviation
mAh milliampere-hours
MHz megahertz
mm millimeter
Nats AMA Nationals
nitro nitromethane
Ni-Cd Nickel Cadmium
NiMH Nickel Metal Hydride
OD outside diameter
RC Radio Control
rpm revolutions per minute
RTF Ready to Fly
SASE self-addressed, stamped
envelope
SIG Special Interest Group
TE trailing edge
Model Aviation’s
Frequently Used Abbreviations /Acronyms
quick rotation to roughly 45° and then we can
release that preset. A lot of guys put it on a
momentary switch. I have it on the switch
closest to my index finger. That allows me to
flip it on and flip it off.
You’re going to get more power if you can
do a flat rotation and throw straight at the
horizon. So you flip the preset switch, do your
spin release, and as soon it gets to the right
angle, you flip that switch off and finish the
climb and then push off over the top. So it’s
important to have a well-tuned launch preset.
JG: Can you DLG when it’s 90° at night and
104° in the daytime? Are there still thermals
out there?
BD: The thermals are really weak. When you
walk outside and see big clouds that are like
cotton candy, then you know that thermals
made those clouds and it’s going to be a good
day. The best thermal days are when we have
a big temperature difference from day to
night. So you want it to be cool at night and
warm during the days. Thermals are there
during the summer, but it’s much more
challenging because they are lighter and
dissolve quicker.
JG: Do you try to visualize the thermal in
your mind or are you working off feel?
BD: There are a whole lot of things going on.
A good learning tool is visualizing how the air
works. Air behaves like water. If there is a tree
line, you can visualize how the air hits that
and gets pushed up into the air and tumbles
over the top.
JG: Like a wave?
BD: Just like a wave. If a thermal comes
down this swirling air, it hits those trees and
gets thrown up into the sky. So that is a really
good visualization practice. When I encounter
a thermal, I always visualize it as a tornado.
That’s your most typical shape, but thermals
can also be blobby donuts as well.
That’s why catching them low is so tough.
They are smaller at the bottom. So when you
are really high it seems like you can just eat
up the sky and fly anywhere you want and not
come down. Up that high you have these great
big thermals. Visualization really does help.
JG: What kind of Sailplanes do you fly?
BD: I fly the Sirius and Polaris by Momentum
Models in Sweden. There are a bunch of great
models out there. I like the Sirius. It’s all
carbon fiber and really strong. It works for
me. I need a model that doesn’t break when I
throw it.
Once you get to the competition-level
Sailplanes, there is not a big difference in
performance. Sometimes a model might give
up lightness to fly better in strong winds.
Some might give up strong wind performance
to do better in light air. There are different
design directions because you can’t really
predict what conditions will be.
Most DLG Sailplanes are designed to do
well in all conditions. When the wind is high,
you can add more lead for ballast. Most
models weigh approximately 11 ounces, so if
I add 2½ ounces, that is a big percentage
increase in weight. It allows me to throw
harder and fly faster. The Sirius is a good allaround
airplane. They are all so close I can’t
strongly recommend one over another.
Get something that is available. By the
time you get a contest DLG Sailplane flying,
you’re going to have a $1,000 in it no matter
which one you buy. Your best bet for an
entry-level airplane is to find a used one. Most
of these guys who fly contests get a ding in
them here and there; they aren’t as clean as
they once were and they don’t want to fly a
contest with a beater. So you can pick it up
and get flying right now. The Blaster is up
there with the $900 models. It’s affordable
and available.
Really, it’s about how much you practice.
So just get something you can get up there
with. DLG is a pretty steep learning curve. So
if it’s already beat up you won’t be
emotionally attached to it.
JG: Is there anything you would like to say to
future DLG pilots?
BD: The best thing you can do is to fly with
someone else who is experienced. You’re
going to learn so much faster and get to that
enjoyment level so much faster if you can get
good instruction from someone who’s already
out there doing it.
Don’t be a fair-weather flier. In the
springtime you will go out there and the
weather is great with big puffy clouds and it is
“all-you-can-eat” thermals, but there is so
much satisfaction in a blustery day when it’s
overcast and gray, blowing 10 mph. You can
get out there and realize the air is just as active
on a crappy day when you would normally sit
on a couch. It’s awesome to go out on a bad
day and throw the airplane and get 3- and 4-
minute flights all day long. It’s like a great
day of fishing, you just keep catching them!
Living here on the thermal farm is a
beautiful thing. When I decide that it’s time to
fly, I pick my model up, pick my transmitter
up, and walk out. There is no other support
equipment needed. What’s really neat is DLG
pilots are passionate about what they do. They
love the challenge, they love the thermals, and
they like to think about when they first started
and all the things that they learned.
I think that you will find the DLG
community is fantastic. Everybody on the
field is really there to help. Everyone wants
you to succeed and find the joy that they find
in Soaring. MA
Sources:
The Bruce F3K
www.thebrucef3k.com
Momentum Model Technologies
www.momentum-mt.se
11sig3.QXD_00MSTRPG.QXD 9/22/11 10:59 AM Page 92