WE LEFT OFF last time with Project
Hole Shot with the fuselage essentially
ready to accept the wing and tail group.
Unlike a built-up-fuselage airplane,
profile models require no additional
woodwork after the wing and tail group are
installed. This gives us a chance to apply a
good deal of the finish before the model
gets “complicated” with which to work.
Getting into the “nooks and crannies”
around the wing and tail assemblies, and
achieving a smooth finish at those
junctions, can be a pain. By applying some
of the finish to the fuselage beforehand, the
final finish can be made to look more
professional and be applied in a fraction of
the normal time.
How much finish can be applied to the
fuselage at this point? Quite a bit, actually!
And it can be made to do more than make the
airplane look pretty.
By nature, profile-fuselage models do not
have a great deal of torsional rigidity. They are fast to build, and
they offer ease of repair for those who are learning to fly, but they
give up the advantage of the more solid wing and tail mount
afforded by the built-up model.
I have always believed that five elements add up to a goodflying
Precision Aerobatics, or Stunt, model.
1) It must be light.
2) It must be perfectly aligned (accurately assembled).
3) It must be rigid.
4) It must be equipped with a strong-running, reliable, easily
tunable, consistent power package (engine, tank, and propeller).
5) It must have a smooth-acting, precisely aligned, strong,longlasting
control system.
If any of the preceding elements is missing, the result is merely
a caricature of a real Stunt model. That’s harsh, but it’s true.
Two of those factors work hand in hand: alignment and
rigidity. If a model is accurate and perfectly aligned while sitting
on your workbench, but that alignment is not maintained under
flight loads, it is inaccurate.
If the wing and tail are allowed to get out of alignment with
each other while maneuvering, all sorts of strange things can
occur. The result is a model that cannot be
used as an effective tool with which to
learn to fly Stunt.
Therefore, it is vital to make our
fuselage as rigid as possible without
adding too much weight. To gain back a
large portion of the inherent low torsional,
or twist, resistance of the profile fuselage,
I highly recommend covering it at this
point with .2-ounce (That’s 2-tenths of an
ounce) carbon mat. It is easy to apply, and
once in place—and the attachment medium
has fully dried or cured—it adds
measurably to the fuselage’s strength and
torsional resistance.
We’ve come to a point where
traditional model-building wisdom and
protocol has reached the crossroads of
integrating new materials into the regimen.
Finish your model professionally, in a fraction of the time, with soft carbon mat
[[email protected]]
Control Line Precision Aerobatics Bob Hunt
The fuselage has two coats of clear modeling dope applied and is ready for the .2-ounce
carbon mat. Use a good-quality camel-hair brush to apply the dope.
Cut a piece of mat that will cover one fuselage side, lay it in place,
and brush the dope onto it. Rub the dope into the carbon mat’s
weave with the palm of your hand.
After the entire fuselage has been covered with the carbon mat, doped, and sanded, it is
ready for the wing and tail assemblies to be installed.
May 2008 161
05sig6.QXD 3/25/08 8:07 AM Page 161
We’ve been bound, to a large degree, by
paradigms in construction techniques that
simply perpetuate age-old deficiencies in
resulting models. It’s time to start taking
advantage of some of the wonderful new
materials that are available to us!
I’ve been covering all my models—
built-up-fuselage and profile types—with
carbon mat (sometimes referred to as
carbon “veil”) for the past several years.
The result has been amazingly rigid
airplanes that are able to maintain their
good flying qualities when the wind starts
to blow hard. Even built-up-fuselage
models begin to twist significantly in heavy
wind conditions.
The carbon mat I use on my models
comes from Aerospace Composite
Products, but other sources sell the same or
a similar material.
Early on there were two types of carbon
mat: one had a “sizing” applied to it and
the other had no sizing. The sizing was
applied to make the mat somewhat stiffer
and easier to roll and handle. The unsized
mat is extraordinarily flimsy and difficult
to roll.
For our purposes it is imperative to
obtain the unsized carbon mat! Do not use
carbon mat that has been treated in any
way with a sizing or stiffening substance.
The sizing used in the stiffer mat does not
allow the material to form easily around
compound curves when covering a model.
What’s worse, the sizing tends to
develop pinhole voids during the sanding
process, after initial application. Many
have reported myriad pinholes in their
finishes, which have been traced to the
inconsistent surface left by the carbon mat
that contained sizing. As it is sanded, the
sizing remains in some areas and is sanding
away in others; the result is the pinholes.
I experienced this problem early on and
quickly switched to the unsized mat. I’ve
had no pinhole problems since.
The nice people at Aerospace Composites
were made aware of this issue and ceased
providing the sized mat, so there will be no
future problems. They call the unsized
material “Soft Carbon Mat.” When you
order it, for safety’s sake specify the Soft
Carbon. If you order from a source other
than Aerospace Composites, specify that
you want unsized material. I guess I’ve
beaten that subject to death!
Applying the carbon mat is easy, but
there are steps you must follow to achieve
the desired results. Brush two or three coats
of clear dope onto the airframe—or in this
case the fuselage. Apply enough coats to
give the surface a satin sheen.
Lay a piece of carbon on one fuselage
side and smooth it so it is as flat as
possible. We will use modeling dope to
attach the carbon mat to the balsa. This
dope has to be thinned to virtually the
consistency of water. It takes a mixture that
is at least 80% thinner, and sometimes even
90% thinner, depending on how “thick”
(viscous) the dope is to begin with.
The idea is to be able to have the dope
flow through the carbon mat and soften the
initial coats of dope that were applied to
the fuselage. If you don’t do this, you run
the risk of not having the carbon 100%
attached to the wood beneath. The result is
a weaker part than is possible with proper
covering technique and the tendency for the
carbon to “pucker” later.
As you brush the dope onto and through
the carbon mat, you can use the palm of
your hand to work out any wrinkles. The
carbon is “friendly” in its willingness to
conform to moderate curves. As you cover
the first side of the fuselage, you can fold
the edge of the carbon onto the opposite
side of the fuselage and stick it down with
dope.
After you have covered one side of the
This month we list those who have donated $10 or more in support of the Academy’s programs, the National Model
Aviation Museum and the International Aeromodeling Center. These people have made more than a donation—they have made
an investment in the future of aeromodeling.
When you see these folks, thank them! They are now among the thousands who have given back to model aviation part of
what model aviation has given to them. Many things will be possible due to their thoughtful giving and generosity.
We list our supporters monthly. These donations represent amounts processed in the month of February 2008. If your
name is not listed, please write to the Membership Department and include a canceled check. We want to recognize all
contributors!
Thank you.
Your Contributions Do Make a Difference!
Roger C. Altizer - WV
Philip H. Azarian - NJ
James P. Baber - VA
Mitchell D. Baker - IN
David R. Becher - NV
James H. Bennett - MO
Mark P. Bim Merle - IL
Michael Boiko - NH
Stephen J. Bolash - FL
James Borre - IL
Robert J. Brainard - OH
Jerry L. Brija - MI
Dan D. Brosz - SD
Jack W. Burnside - AZ
Matthew F. Burris - CA
Kent E. Buse - OR
Ernie D. Cardwell - KY
Christian Carrillo - CA
Russell S. Chappell - CA
David H. Cook - IN
David G. Copeman - MI
John L. Crossman - AZ
Cameron D. De Van - CA
Jason D. Deloach - CA
Anthony L. Dilluvio - NY
Denny L. Dock - MI
Lewis L. Dunmire - PA
David Espinoza - CA
Tyson Etheridge - FL
Mark E. Franke - VA
Lawrence F. Garvin - CT
Susan D. Harp - GA
David L. Hartman - VA
Randall F. Heisey - PA
R. Dalton Hendrix - NC
Richard W. Herdell - CA
Michael Holbrook Jr. - GA
David R. Hollinbeck - CA
Michael E. Hormann - OR
Scott C. Hudson - ME
August H. Hummert III - MO
Raymond J. Hutaff - HI
William H. Jordan - NJ
Daniel W. Jouppi - MN
Jeff Keith - NJ
Howard P. Klemmetsen - GA
Daniel Laramie - MA
Michael Law - NJ
Bernard A. Liskov - CT
Howard T. Marano - PA
Anthony J. Martin - TX
Joseph H. Martin - CA
Jorge Matos - VA
David McDowell - CA
Don Meierhoff - AK
Franklin D. Mickelson - UT
Robert T. Ottlinger - KY
Ty Prause - TX
Charles G. Rice - OH
Christopher W. Rix - IN
Samuel Rodriguez - CT
Guy R. Scott - IN
Charles J. Slusarczyk - OH
Harold J. Stranix - OR
Thomas F. Teel - NJ
Joseph H. Trader Jr. - FL
Ralph Turner - OH
Felipe Uriarte - TX
Joshua E. Venable - LA
Eric Wallgren - MD
William Wherritt - CA
Lawrence J. Whitcomb - LA
Daniel L. Wilson - TN
$10 up to $100
Community Foundation of NJ - NJ
Donald R. Decook - IN
David Lomax - NC
Bruce Nordquist - OH
Ronald C. Phillips - NY
Princeton Area Radio Kontrol Soc. - WV
$100 up to $500
162 MODEL AVIATION
05sig6.QXD 3/25/08 8:09 AM Page 162
Edition: Model Aviation - 2008/05
Page Numbers: 161,162
Edition: Model Aviation - 2008/05
Page Numbers: 161,162
WE LEFT OFF last time with Project
Hole Shot with the fuselage essentially
ready to accept the wing and tail group.
Unlike a built-up-fuselage airplane,
profile models require no additional
woodwork after the wing and tail group are
installed. This gives us a chance to apply a
good deal of the finish before the model
gets “complicated” with which to work.
Getting into the “nooks and crannies”
around the wing and tail assemblies, and
achieving a smooth finish at those
junctions, can be a pain. By applying some
of the finish to the fuselage beforehand, the
final finish can be made to look more
professional and be applied in a fraction of
the normal time.
How much finish can be applied to the
fuselage at this point? Quite a bit, actually!
And it can be made to do more than make the
airplane look pretty.
By nature, profile-fuselage models do not
have a great deal of torsional rigidity. They are fast to build, and
they offer ease of repair for those who are learning to fly, but they
give up the advantage of the more solid wing and tail mount
afforded by the built-up model.
I have always believed that five elements add up to a goodflying
Precision Aerobatics, or Stunt, model.
1) It must be light.
2) It must be perfectly aligned (accurately assembled).
3) It must be rigid.
4) It must be equipped with a strong-running, reliable, easily
tunable, consistent power package (engine, tank, and propeller).
5) It must have a smooth-acting, precisely aligned, strong,longlasting
control system.
If any of the preceding elements is missing, the result is merely
a caricature of a real Stunt model. That’s harsh, but it’s true.
Two of those factors work hand in hand: alignment and
rigidity. If a model is accurate and perfectly aligned while sitting
on your workbench, but that alignment is not maintained under
flight loads, it is inaccurate.
If the wing and tail are allowed to get out of alignment with
each other while maneuvering, all sorts of strange things can
occur. The result is a model that cannot be
used as an effective tool with which to
learn to fly Stunt.
Therefore, it is vital to make our
fuselage as rigid as possible without
adding too much weight. To gain back a
large portion of the inherent low torsional,
or twist, resistance of the profile fuselage,
I highly recommend covering it at this
point with .2-ounce (That’s 2-tenths of an
ounce) carbon mat. It is easy to apply, and
once in place—and the attachment medium
has fully dried or cured—it adds
measurably to the fuselage’s strength and
torsional resistance.
We’ve come to a point where
traditional model-building wisdom and
protocol has reached the crossroads of
integrating new materials into the regimen.
Finish your model professionally, in a fraction of the time, with soft carbon mat
[[email protected]]
Control Line Precision Aerobatics Bob Hunt
The fuselage has two coats of clear modeling dope applied and is ready for the .2-ounce
carbon mat. Use a good-quality camel-hair brush to apply the dope.
Cut a piece of mat that will cover one fuselage side, lay it in place,
and brush the dope onto it. Rub the dope into the carbon mat’s
weave with the palm of your hand.
After the entire fuselage has been covered with the carbon mat, doped, and sanded, it is
ready for the wing and tail assemblies to be installed.
May 2008 161
05sig6.QXD 3/25/08 8:07 AM Page 161
We’ve been bound, to a large degree, by
paradigms in construction techniques that
simply perpetuate age-old deficiencies in
resulting models. It’s time to start taking
advantage of some of the wonderful new
materials that are available to us!
I’ve been covering all my models—
built-up-fuselage and profile types—with
carbon mat (sometimes referred to as
carbon “veil”) for the past several years.
The result has been amazingly rigid
airplanes that are able to maintain their
good flying qualities when the wind starts
to blow hard. Even built-up-fuselage
models begin to twist significantly in heavy
wind conditions.
The carbon mat I use on my models
comes from Aerospace Composite
Products, but other sources sell the same or
a similar material.
Early on there were two types of carbon
mat: one had a “sizing” applied to it and
the other had no sizing. The sizing was
applied to make the mat somewhat stiffer
and easier to roll and handle. The unsized
mat is extraordinarily flimsy and difficult
to roll.
For our purposes it is imperative to
obtain the unsized carbon mat! Do not use
carbon mat that has been treated in any
way with a sizing or stiffening substance.
The sizing used in the stiffer mat does not
allow the material to form easily around
compound curves when covering a model.
What’s worse, the sizing tends to
develop pinhole voids during the sanding
process, after initial application. Many
have reported myriad pinholes in their
finishes, which have been traced to the
inconsistent surface left by the carbon mat
that contained sizing. As it is sanded, the
sizing remains in some areas and is sanding
away in others; the result is the pinholes.
I experienced this problem early on and
quickly switched to the unsized mat. I’ve
had no pinhole problems since.
The nice people at Aerospace Composites
were made aware of this issue and ceased
providing the sized mat, so there will be no
future problems. They call the unsized
material “Soft Carbon Mat.” When you
order it, for safety’s sake specify the Soft
Carbon. If you order from a source other
than Aerospace Composites, specify that
you want unsized material. I guess I’ve
beaten that subject to death!
Applying the carbon mat is easy, but
there are steps you must follow to achieve
the desired results. Brush two or three coats
of clear dope onto the airframe—or in this
case the fuselage. Apply enough coats to
give the surface a satin sheen.
Lay a piece of carbon on one fuselage
side and smooth it so it is as flat as
possible. We will use modeling dope to
attach the carbon mat to the balsa. This
dope has to be thinned to virtually the
consistency of water. It takes a mixture that
is at least 80% thinner, and sometimes even
90% thinner, depending on how “thick”
(viscous) the dope is to begin with.
The idea is to be able to have the dope
flow through the carbon mat and soften the
initial coats of dope that were applied to
the fuselage. If you don’t do this, you run
the risk of not having the carbon 100%
attached to the wood beneath. The result is
a weaker part than is possible with proper
covering technique and the tendency for the
carbon to “pucker” later.
As you brush the dope onto and through
the carbon mat, you can use the palm of
your hand to work out any wrinkles. The
carbon is “friendly” in its willingness to
conform to moderate curves. As you cover
the first side of the fuselage, you can fold
the edge of the carbon onto the opposite
side of the fuselage and stick it down with
dope.
After you have covered one side of the
This month we list those who have donated $10 or more in support of the Academy’s programs, the National Model
Aviation Museum and the International Aeromodeling Center. These people have made more than a donation—they have made
an investment in the future of aeromodeling.
When you see these folks, thank them! They are now among the thousands who have given back to model aviation part of
what model aviation has given to them. Many things will be possible due to their thoughtful giving and generosity.
We list our supporters monthly. These donations represent amounts processed in the month of February 2008. If your
name is not listed, please write to the Membership Department and include a canceled check. We want to recognize all
contributors!
Thank you.
Your Contributions Do Make a Difference!
Roger C. Altizer - WV
Philip H. Azarian - NJ
James P. Baber - VA
Mitchell D. Baker - IN
David R. Becher - NV
James H. Bennett - MO
Mark P. Bim Merle - IL
Michael Boiko - NH
Stephen J. Bolash - FL
James Borre - IL
Robert J. Brainard - OH
Jerry L. Brija - MI
Dan D. Brosz - SD
Jack W. Burnside - AZ
Matthew F. Burris - CA
Kent E. Buse - OR
Ernie D. Cardwell - KY
Christian Carrillo - CA
Russell S. Chappell - CA
David H. Cook - IN
David G. Copeman - MI
John L. Crossman - AZ
Cameron D. De Van - CA
Jason D. Deloach - CA
Anthony L. Dilluvio - NY
Denny L. Dock - MI
Lewis L. Dunmire - PA
David Espinoza - CA
Tyson Etheridge - FL
Mark E. Franke - VA
Lawrence F. Garvin - CT
Susan D. Harp - GA
David L. Hartman - VA
Randall F. Heisey - PA
R. Dalton Hendrix - NC
Richard W. Herdell - CA
Michael Holbrook Jr. - GA
David R. Hollinbeck - CA
Michael E. Hormann - OR
Scott C. Hudson - ME
August H. Hummert III - MO
Raymond J. Hutaff - HI
William H. Jordan - NJ
Daniel W. Jouppi - MN
Jeff Keith - NJ
Howard P. Klemmetsen - GA
Daniel Laramie - MA
Michael Law - NJ
Bernard A. Liskov - CT
Howard T. Marano - PA
Anthony J. Martin - TX
Joseph H. Martin - CA
Jorge Matos - VA
David McDowell - CA
Don Meierhoff - AK
Franklin D. Mickelson - UT
Robert T. Ottlinger - KY
Ty Prause - TX
Charles G. Rice - OH
Christopher W. Rix - IN
Samuel Rodriguez - CT
Guy R. Scott - IN
Charles J. Slusarczyk - OH
Harold J. Stranix - OR
Thomas F. Teel - NJ
Joseph H. Trader Jr. - FL
Ralph Turner - OH
Felipe Uriarte - TX
Joshua E. Venable - LA
Eric Wallgren - MD
William Wherritt - CA
Lawrence J. Whitcomb - LA
Daniel L. Wilson - TN
$10 up to $100
Community Foundation of NJ - NJ
Donald R. Decook - IN
David Lomax - NC
Bruce Nordquist - OH
Ronald C. Phillips - NY
Princeton Area Radio Kontrol Soc. - WV
$100 up to $500
162 MODEL AVIATION
05sig6.QXD 3/25/08 8:09 AM Page 162