I’VE HAD A whole lot of fun since the last
column, thinking about electric-powered
Navy Carrier. That has led me to rethink
potential prototype designs for the Class I
and Class II events. Most of the issues are
the same, whether we are considering
official glow-powered AMA categories or
the electric-powered Navy Carrier Society
unofficial events.
I thought I had identified the ideal
prototype in the Short Seamew. I have looked
at several options in the past but have come
up with one that I have neglected to evaluate
until recently. I think it will surprise you.
I’VE HAD A whole lot of fun since the last
column, thinking about electric-powered
Navy Carrier. That has led me to rethink
potential prototype designs for the Class I
and Class II events. Most of the issues are
the same, whether we are considering
official glow-powered AMA categories or
In selecting a prototype aircraft to model
for Class I and Class II, I have two primary
considerations. Performance is a high
priority, followed by good looks and
modeling unique aircraft (even though I fly
MO-1s).
Performance comes in two forms: high
speed and low speed, and we Navy Carrier
competitors need them both for a good
score. I’ll discuss low speed first, because
its requirements determine the size of our
airplanes.
I’ve done many analyses of Carriermodel
performance. Two factors are highly
correlated to good low-speed scores, the
first of which is a good high-speed score.
That might seem incorrect on the surface,
but, in looking at factors that statistically
influence low-speed scores, pilots who
excel in high speed also do well in low
speed.
I assume that this fact is related to
practice. The more you work on the hobby,
the better your scores will be for both high
and low speed.
The next highest correlation to good
low-speed performance is wing loading.
The lower the wing loading, the better the
low-speed performance. That makes good
sense, whether the model is flying or
hanging.
One can reduce wing loading by
decreasing the weight or enlarging the
aircraft. As models grow in size, they grow
in weight in rough proportion to wing area.
That doesn’t make sense (it should be in
proportion to volume—not area) until you
realize that we tend to use the same size
wood, same covering, and same paint finish
out of habit, and all of those choices affect
the weight in proportion to area. With the
weight of the engine, fuel system, control
system, and landing-gear constant, bigger
models produce lighter wing loadings.
For that reason, for optimum low-speed
performance, an airplane should have a 44-
inch wingspan. That will be the assumption
for the high-speed discussion.
High speed depends on reducing drag. I
recognize that the engine is a major factor in
high-speed performance, but I’m discussing
model design.
Drag reduction depends primarily on a
couple of factors related to the airplane’s
design. Appropriate airfoil and angle-ofattack
distribution for the wing, which I’ve
written about in the past, is not strongly
related to the prototype design. However,
profile drag is strongly influenced by the
prototype.
There are three primary contributors to the
drag of the model’s nonlifting parts: fuselage
cross-section, fuselage shape, and engine
drag. Fuselage drag from cross-section is
relatively straightforward; the bigger the
fuselage cross-section, the higher the drag for
a given shape. The shape of the fuselage
influences drag by increasing or reducing
airflow separation.
Radial-engine prototypes, with their big,
round cowls, can be a drag (literally) if they
are designed poorly, but proper internal
design, spinners, etc. can eliminate much of
the disadvantage. The primary drag producer
on our aircraft is the engine. A relatively large
(in comparison to the fuselage) cylinder
sticking out in the breeze is the culprit.
A prototype’s sleek nose can be
completely dominated by the drag of the
engine, which it leaves exposed. A radialengine
cowl can produce less total drag if it
encloses more of the engine.
Let’s look at the most popular Navy
Carrier model: the MO-1. In fuselage crosssection,
it comes out ahead of all prototypes I
can think of. Those of us who try to squeeze
control systems and fuel tanks into MO-1s
can attest to that.
The next best prototype is the Short
Seamew; that’s why I like it so much. The
Seamew is only approximately 30% larger in
cross-section than the MO-1.
Other prototypes that fare well in the
fuselage-cross-section department are the
standard Supermarine Seafire at 40% larger
and the Curtiss SO3C Seamew (there’s
something about that name) at 65% larger.
Most radial-engine prototypes come out at
roughly double the MO-1.
The MO-1 is a big loser in fuselage
shape, with its box cross-section and
relatively sharp edges. It also loses big on the
engine exposure part of the equation. With a
large Class II engine, the crankcase even
sticks out on the inboard side!
That’s where the Seamew shines, with the
entire engine blending in smoothly to the
fuselage behind it (with a vertically mounted
engine). The Seafire hides another 0.6 inch
of engine cylinder compared to the MO-1,
and the other Seamew (the Curtiss) can hide
the whole engine if you’re willing to accept
an inverted installation.
Where does all this leave us in terms of
prototype aircraft? If bigger is better for lowspeed
performance, larger wing area is a
desirable feature.
Assuming that all models are built to
scale with a 44-inch wingspan, the MO-1
standard comes out at 345 square inches of
wing area, which beats many prototypes but
is far from the best. The Short Seamew
produces 380 square inches. The Curtiss
Seamew comes in at 393 square inches. The
Vought OS2U Kingfisher squares out at 410.
Most of the usual suspects beat the MO-
1, coming in between 350 and 370 square
inches, but you need to check each potential
design. The standard Supermarine Seafire,
which I mentioned, is slightly smaller than
that, at 348 square inches.
The biggest model I found in terms of
wing area comes out at more than 430 square
inches. The real surprise was that this
prototype was the Supermarine Seafire! How
can this be? The British did numerous things
to the Seafire and Spitfire designs, including
changing wingtip design to try to get better
high- and low-altitude performance.
The Seafire L. Mk IIC was derived from
the Spitfire VC. The L designation indicates
that it was intended for low-level operations.
The L also means that the wingspan was
reduced from 36 feet, 10 inches to 32 feet, 2
inches. That reduction, along with the loss of
the relatively small wingtips, which were
removed to achieve the span reduction,
produces an increase in wing area of 85
square inches if both models are built to 44
inches in wingspan.
I hope to see many of you at the CL Navy
Carrier Nats, which will be held July 7-10 at
the International Aeromodeling Center in
Muncie, Indiana. Those who can’t make it
can follow the action in the NatsNews
newsletter on the AMA Web site. MA
Sources:
Seafire L. Mk II:
http://en.wikipedia.org/wiki/Supermarine_Sea
fire
Glenn L. Martin MO-1:
http://en.wikipedia.org/wiki/Martin_MO
Curtiss SO3C Seamew
http://en.wikipedia.org/wiki/SO3C_Seamew
Vought OS2U Kingfisher
http://en.wikipedia.org/wiki/Vought_OS2U_
Kingfisher
Navy Carrier Society
http://clflyer.tripod.com/ncs/ncs.htm
Edition: Model Aviation - 2009/07
Page Numbers: 133,134,135
Edition: Model Aviation - 2009/07
Page Numbers: 133,134,135
I’VE HAD A whole lot of fun since the last
column, thinking about electric-powered
Navy Carrier. That has led me to rethink
potential prototype designs for the Class I
and Class II events. Most of the issues are
the same, whether we are considering
official glow-powered AMA categories or
the electric-powered Navy Carrier Society
unofficial events.
I thought I had identified the ideal
prototype in the Short Seamew. I have looked
at several options in the past but have come
up with one that I have neglected to evaluate
until recently. I think it will surprise you.
I’VE HAD A whole lot of fun since the last
column, thinking about electric-powered
Navy Carrier. That has led me to rethink
potential prototype designs for the Class I
and Class II events. Most of the issues are
the same, whether we are considering
official glow-powered AMA categories or
In selecting a prototype aircraft to model
for Class I and Class II, I have two primary
considerations. Performance is a high
priority, followed by good looks and
modeling unique aircraft (even though I fly
MO-1s).
Performance comes in two forms: high
speed and low speed, and we Navy Carrier
competitors need them both for a good
score. I’ll discuss low speed first, because
its requirements determine the size of our
airplanes.
I’ve done many analyses of Carriermodel
performance. Two factors are highly
correlated to good low-speed scores, the
first of which is a good high-speed score.
That might seem incorrect on the surface,
but, in looking at factors that statistically
influence low-speed scores, pilots who
excel in high speed also do well in low
speed.
I assume that this fact is related to
practice. The more you work on the hobby,
the better your scores will be for both high
and low speed.
The next highest correlation to good
low-speed performance is wing loading.
The lower the wing loading, the better the
low-speed performance. That makes good
sense, whether the model is flying or
hanging.
One can reduce wing loading by
decreasing the weight or enlarging the
aircraft. As models grow in size, they grow
in weight in rough proportion to wing area.
That doesn’t make sense (it should be in
proportion to volume—not area) until you
realize that we tend to use the same size
wood, same covering, and same paint finish
out of habit, and all of those choices affect
the weight in proportion to area. With the
weight of the engine, fuel system, control
system, and landing-gear constant, bigger
models produce lighter wing loadings.
For that reason, for optimum low-speed
performance, an airplane should have a 44-
inch wingspan. That will be the assumption
for the high-speed discussion.
High speed depends on reducing drag. I
recognize that the engine is a major factor in
high-speed performance, but I’m discussing
model design.
Drag reduction depends primarily on a
couple of factors related to the airplane’s
design. Appropriate airfoil and angle-ofattack
distribution for the wing, which I’ve
written about in the past, is not strongly
related to the prototype design. However,
profile drag is strongly influenced by the
prototype.
There are three primary contributors to the
drag of the model’s nonlifting parts: fuselage
cross-section, fuselage shape, and engine
drag. Fuselage drag from cross-section is
relatively straightforward; the bigger the
fuselage cross-section, the higher the drag for
a given shape. The shape of the fuselage
influences drag by increasing or reducing
airflow separation.
Radial-engine prototypes, with their big,
round cowls, can be a drag (literally) if they
are designed poorly, but proper internal
design, spinners, etc. can eliminate much of
the disadvantage. The primary drag producer
on our aircraft is the engine. A relatively large
(in comparison to the fuselage) cylinder
sticking out in the breeze is the culprit.
A prototype’s sleek nose can be
completely dominated by the drag of the
engine, which it leaves exposed. A radialengine
cowl can produce less total drag if it
encloses more of the engine.
Let’s look at the most popular Navy
Carrier model: the MO-1. In fuselage crosssection,
it comes out ahead of all prototypes I
can think of. Those of us who try to squeeze
control systems and fuel tanks into MO-1s
can attest to that.
The next best prototype is the Short
Seamew; that’s why I like it so much. The
Seamew is only approximately 30% larger in
cross-section than the MO-1.
Other prototypes that fare well in the
fuselage-cross-section department are the
standard Supermarine Seafire at 40% larger
and the Curtiss SO3C Seamew (there’s
something about that name) at 65% larger.
Most radial-engine prototypes come out at
roughly double the MO-1.
The MO-1 is a big loser in fuselage
shape, with its box cross-section and
relatively sharp edges. It also loses big on the
engine exposure part of the equation. With a
large Class II engine, the crankcase even
sticks out on the inboard side!
That’s where the Seamew shines, with the
entire engine blending in smoothly to the
fuselage behind it (with a vertically mounted
engine). The Seafire hides another 0.6 inch
of engine cylinder compared to the MO-1,
and the other Seamew (the Curtiss) can hide
the whole engine if you’re willing to accept
an inverted installation.
Where does all this leave us in terms of
prototype aircraft? If bigger is better for lowspeed
performance, larger wing area is a
desirable feature.
Assuming that all models are built to
scale with a 44-inch wingspan, the MO-1
standard comes out at 345 square inches of
wing area, which beats many prototypes but
is far from the best. The Short Seamew
produces 380 square inches. The Curtiss
Seamew comes in at 393 square inches. The
Vought OS2U Kingfisher squares out at 410.
Most of the usual suspects beat the MO-
1, coming in between 350 and 370 square
inches, but you need to check each potential
design. The standard Supermarine Seafire,
which I mentioned, is slightly smaller than
that, at 348 square inches.
The biggest model I found in terms of
wing area comes out at more than 430 square
inches. The real surprise was that this
prototype was the Supermarine Seafire! How
can this be? The British did numerous things
to the Seafire and Spitfire designs, including
changing wingtip design to try to get better
high- and low-altitude performance.
The Seafire L. Mk IIC was derived from
the Spitfire VC. The L designation indicates
that it was intended for low-level operations.
The L also means that the wingspan was
reduced from 36 feet, 10 inches to 32 feet, 2
inches. That reduction, along with the loss of
the relatively small wingtips, which were
removed to achieve the span reduction,
produces an increase in wing area of 85
square inches if both models are built to 44
inches in wingspan.
I hope to see many of you at the CL Navy
Carrier Nats, which will be held July 7-10 at
the International Aeromodeling Center in
Muncie, Indiana. Those who can’t make it
can follow the action in the NatsNews
newsletter on the AMA Web site. MA
Sources:
Seafire L. Mk II:
http://en.wikipedia.org/wiki/Supermarine_Sea
fire
Glenn L. Martin MO-1:
http://en.wikipedia.org/wiki/Martin_MO
Curtiss SO3C Seamew
http://en.wikipedia.org/wiki/SO3C_Seamew
Vought OS2U Kingfisher
http://en.wikipedia.org/wiki/Vought_OS2U_
Kingfisher
Navy Carrier Society
http://clflyer.tripod.com/ncs/ncs.htm
Edition: Model Aviation - 2009/07
Page Numbers: 133,134,135
I’VE HAD A whole lot of fun since the last
column, thinking about electric-powered
Navy Carrier. That has led me to rethink
potential prototype designs for the Class I
and Class II events. Most of the issues are
the same, whether we are considering
official glow-powered AMA categories or
the electric-powered Navy Carrier Society
unofficial events.
I thought I had identified the ideal
prototype in the Short Seamew. I have looked
at several options in the past but have come
up with one that I have neglected to evaluate
until recently. I think it will surprise you.
I’VE HAD A whole lot of fun since the last
column, thinking about electric-powered
Navy Carrier. That has led me to rethink
potential prototype designs for the Class I
and Class II events. Most of the issues are
the same, whether we are considering
official glow-powered AMA categories or
In selecting a prototype aircraft to model
for Class I and Class II, I have two primary
considerations. Performance is a high
priority, followed by good looks and
modeling unique aircraft (even though I fly
MO-1s).
Performance comes in two forms: high
speed and low speed, and we Navy Carrier
competitors need them both for a good
score. I’ll discuss low speed first, because
its requirements determine the size of our
airplanes.
I’ve done many analyses of Carriermodel
performance. Two factors are highly
correlated to good low-speed scores, the
first of which is a good high-speed score.
That might seem incorrect on the surface,
but, in looking at factors that statistically
influence low-speed scores, pilots who
excel in high speed also do well in low
speed.
I assume that this fact is related to
practice. The more you work on the hobby,
the better your scores will be for both high
and low speed.
The next highest correlation to good
low-speed performance is wing loading.
The lower the wing loading, the better the
low-speed performance. That makes good
sense, whether the model is flying or
hanging.
One can reduce wing loading by
decreasing the weight or enlarging the
aircraft. As models grow in size, they grow
in weight in rough proportion to wing area.
That doesn’t make sense (it should be in
proportion to volume—not area) until you
realize that we tend to use the same size
wood, same covering, and same paint finish
out of habit, and all of those choices affect
the weight in proportion to area. With the
weight of the engine, fuel system, control
system, and landing-gear constant, bigger
models produce lighter wing loadings.
For that reason, for optimum low-speed
performance, an airplane should have a 44-
inch wingspan. That will be the assumption
for the high-speed discussion.
High speed depends on reducing drag. I
recognize that the engine is a major factor in
high-speed performance, but I’m discussing
model design.
Drag reduction depends primarily on a
couple of factors related to the airplane’s
design. Appropriate airfoil and angle-ofattack
distribution for the wing, which I’ve
written about in the past, is not strongly
related to the prototype design. However,
profile drag is strongly influenced by the
prototype.
There are three primary contributors to the
drag of the model’s nonlifting parts: fuselage
cross-section, fuselage shape, and engine
drag. Fuselage drag from cross-section is
relatively straightforward; the bigger the
fuselage cross-section, the higher the drag for
a given shape. The shape of the fuselage
influences drag by increasing or reducing
airflow separation.
Radial-engine prototypes, with their big,
round cowls, can be a drag (literally) if they
are designed poorly, but proper internal
design, spinners, etc. can eliminate much of
the disadvantage. The primary drag producer
on our aircraft is the engine. A relatively large
(in comparison to the fuselage) cylinder
sticking out in the breeze is the culprit.
A prototype’s sleek nose can be
completely dominated by the drag of the
engine, which it leaves exposed. A radialengine
cowl can produce less total drag if it
encloses more of the engine.
Let’s look at the most popular Navy
Carrier model: the MO-1. In fuselage crosssection,
it comes out ahead of all prototypes I
can think of. Those of us who try to squeeze
control systems and fuel tanks into MO-1s
can attest to that.
The next best prototype is the Short
Seamew; that’s why I like it so much. The
Seamew is only approximately 30% larger in
cross-section than the MO-1.
Other prototypes that fare well in the
fuselage-cross-section department are the
standard Supermarine Seafire at 40% larger
and the Curtiss SO3C Seamew (there’s
something about that name) at 65% larger.
Most radial-engine prototypes come out at
roughly double the MO-1.
The MO-1 is a big loser in fuselage
shape, with its box cross-section and
relatively sharp edges. It also loses big on the
engine exposure part of the equation. With a
large Class II engine, the crankcase even
sticks out on the inboard side!
That’s where the Seamew shines, with the
entire engine blending in smoothly to the
fuselage behind it (with a vertically mounted
engine). The Seafire hides another 0.6 inch
of engine cylinder compared to the MO-1,
and the other Seamew (the Curtiss) can hide
the whole engine if you’re willing to accept
an inverted installation.
Where does all this leave us in terms of
prototype aircraft? If bigger is better for lowspeed
performance, larger wing area is a
desirable feature.
Assuming that all models are built to
scale with a 44-inch wingspan, the MO-1
standard comes out at 345 square inches of
wing area, which beats many prototypes but
is far from the best. The Short Seamew
produces 380 square inches. The Curtiss
Seamew comes in at 393 square inches. The
Vought OS2U Kingfisher squares out at 410.
Most of the usual suspects beat the MO-
1, coming in between 350 and 370 square
inches, but you need to check each potential
design. The standard Supermarine Seafire,
which I mentioned, is slightly smaller than
that, at 348 square inches.
The biggest model I found in terms of
wing area comes out at more than 430 square
inches. The real surprise was that this
prototype was the Supermarine Seafire! How
can this be? The British did numerous things
to the Seafire and Spitfire designs, including
changing wingtip design to try to get better
high- and low-altitude performance.
The Seafire L. Mk IIC was derived from
the Spitfire VC. The L designation indicates
that it was intended for low-level operations.
The L also means that the wingspan was
reduced from 36 feet, 10 inches to 32 feet, 2
inches. That reduction, along with the loss of
the relatively small wingtips, which were
removed to achieve the span reduction,
produces an increase in wing area of 85
square inches if both models are built to 44
inches in wingspan.
I hope to see many of you at the CL Navy
Carrier Nats, which will be held July 7-10 at
the International Aeromodeling Center in
Muncie, Indiana. Those who can’t make it
can follow the action in the NatsNews
newsletter on the AMA Web site. MA
Sources:
Seafire L. Mk II:
http://en.wikipedia.org/wiki/Supermarine_Sea
fire
Glenn L. Martin MO-1:
http://en.wikipedia.org/wiki/Martin_MO
Curtiss SO3C Seamew
http://en.wikipedia.org/wiki/SO3C_Seamew
Vought OS2U Kingfisher
http://en.wikipedia.org/wiki/Vought_OS2U_
Kingfisher
Navy Carrier Society
http://clflyer.tripod.com/ncs/ncs.htm