Joe Wagner
T h e E n g i n e S h o p
212 S. Pine Ave., Ozark AL 36360
The new SuperTigre G-61 ABC. Its ringed G-75 “big brother” is
externally identical but 1 millimeter taller.
Large molded-plastic engine mounts need surface truing before
use. A big “mill file” ensures flat mounting areas.
New RCV91-CD rotary-sleeve-valve four-stroke is roughly the
same overall size as an O.S. .60 two-stroke but 4 ounces heavier.
Wal-Mart and AutoZone can provide fuel ingredients for RC
Assist fliers of Old-Timer models with spark-ignition engines.
SUPERTIGRE engines are back! They originated in Italy in 1948
and quickly made a winning reputation for themselves in European
power-model competition. A worldwide demand followed. And 20
years later, SuperTigre developed the first aluminum-brass-chrome
(ABC) model engines. The company has been manufacturing and
improving those ever since.
Today’s new SuperTigre engines are being made in China. The
overall quality of their materials and construction is at least 96% as
good as the earlier Italian-made engines—and the new prices are
astonishingly lower.
I acquired two of the larger RC SuperTigres last summer: a
G-61 ABC and a G-75 of the ringed-piston type. (The G-61 is
also available with a ringed piston.) They are so much alike that
it’s difficult to tell them apart visually.
They use exactly the same mounting dimensions. The G-75 is a
mere .040 inch taller than the G-61 and weighs roughly one-third of
an ounce more (26.53 for the G-61 and 26.88 for the G-75). However,
the G-75 is significantly more powerful. It certainly ought to be, with
23% greater displacement!
Both of my new SuperTigres started quite easily by hand from the
first try. The G-61 especially impressed me because I don’t
particularly enjoy the typical “tight squeak at Top Dead Center
(TDC)” feel of most ABC- and aluminum-brass-nickel (ABN)-type
model engines.
Some of those I’ve recently tested required warming their heads
for a few minutes with a heat gun to loosen the piston-to-cylinder fit
at TDC enough to make initial starting possible. I had no such
problems with the SuperTigre ABC. Its piston is fitted rather snugly
Aero-Ply TIM module, three-cell Ni-Cd pack provide reliability in
operating old-time spark engines. No “booster battery” needed.
in its bore at the top of its stroke—but not excessively so. Even at 60°
ambient temperature, I could easily flip the propeller by hand and
obtain immediate starting.
I’m not really surprised, though. SuperTigre has been making
ABCs for more than 35 years. By this time the company obviously
knows precisely how to optimize the fits.
SuperTigre provides plenty of useful documentation with its
engines. A “generic” instruction booklet covers all of the company’s
engines, from the G-34 to the G-2300. Clearly labeled photographs
and line drawings illustrate correct installation.
There is also a two-page troubleshooting “logic diagram” that lists
all major possible causes of engine malfunction. In simple language
this diagram tells how to overcome the problems. Recommended
propeller sizes and fuels are specified in this booklet too.
Each SuperTigre engine comes with a folder of exploded views:
one of the particular-size engine itself and the other of its carburetor.
In these drawings, all of the individual parts are identified and listed.
That will make ordering replacements easy and accurate. The folder
also provides complete engine mounting dimensions.
SuperTigre even supplies a sizable sheet of company logo and
spectacular tiger decals with each engine! Everything I’ve mentioned
comes neatly packaged in a protective foam-compartmented box.
Some assembly is necessary, but the only item that might prove a
trifle bothersome to install is the brass nut which retains the
carburetor’s clamping bolt. Don’t use long-nose pliers to tighten this
nut! There’s not much clearance space around it, and pliers will
inevitably slip and deform the soft brass. Even if you have to make the
tool yourself, use nothing but a small open-end wrench (or a metric
socket) on this nut.
I did have some trouble setting up the two SuperTigres for testbench
break-in and running; they wouldn’t fit conveniently in any of
my universal test mounts. Instead, I bought a big molded-plastic radial
mount that was the proper size to fit the SuperTigres. That was so I
could install it on a specially made hardwood fixture containing a fuel
tank and a throttle pushrod arrangement. (I described and showed my
custom test stand design in an earlier column.)
But when I removed the radial mount from its plastic bag, I
immediately saw that its mounting surfaces were far from smooth and
flat. That was the result of shrinkage that occurs when the molten
injection-molded plastic cools. (There’s no way of avoiding this,
especially in areas with thick cross-sections.)
Flat mounting surfaces—on the engine-beam tops and the rear
surface that contacts the firewall—are essential for reliable, lowvibration
engine operation. To correct the uneven-surface problem, I
clamped my new plastic radial mount firmly in a workbench vise and
carefully filed the mounting surfaces flat with a big, sharp-toothed
mill file.
(Files do get dull, as do any cutting tools, and then they are as
unsuitable for doing quick and accurate work as dull knives are. New
files don’t cost much, and they make the job much faster and easier.)
Mounting the SuperTigres to my filed-flat radial mount
provided a good opportunity for me to try a new tool: Tower
Hobbies’ Dead Center Hole Locator. It’s a most ingenious device
for accurately locating engine mounting-hole positions—in beammounting
lugs and in models’ firewalls.
This hole locator is much easier to use than to describe. It has a
small drill bit at the end of a long, thin, spring-loaded shaft. A
knurled knob at one end of the tool is used to manually rotate the
drill bit. The other end terminates in a conical guide. That centers
the bit precisely in an engine lug’s mounting hole while the bit is
being turned, making a “pilot hole” to accurately locate the
mounting-screw positions.
I discard the self-tapping engine-mounting screws that come
with most of the molded-plastic radial mounts. They are tough to
install and even worse to remove. Instead, I use my drill press to
make tapped holes for standard socket-head machine screws.
Doing the job that way takes only slightly longer to set up, and it
saves far more time—and frustration—when installing and
removing the engine-attachment screws.
I acquired another big, new engine that needs a specially made
test mount before I can test-run it: the RCV91-CD, which is
RCV’s latest crankshaft-drive four-stroke. I greatly admired the
earlier 58-CD, and I expect its “big brother” to run just as well.
I’ll report further on this engine in the next column—and the
special test-mount design I’ve come up with to simplify the job of
test-running today’s crop of big model engines.
Although almost all spark-ignition model engines went out of
production more than a half-century ago, a surprising number of
them have survived and are in good working condition. And
flying the classic FF designs of yesteryear with antique power
plants has become fairly popular—especially via “RC Assist.”
(That eliminates most of the cross-country chasing and treeclimbing
that used to be such an unpleasant but inescapable part
of Gas-model FF activities.)
Two aspects of operating old-time spark engines nowadays
have been presenting problems, one of which is fuel. The original
“standard formula” was three parts of “white gas” and one part of
“70-weight” nondetergent motor oil, but you can’t find either of
those at gas stations anymore.
Today’s automotive gasoline isn’t good for use in old-time
model engines. For one thing, its octane rating is much higher
than that of “white gas,” which can make for difficult starting. For
another, model engines with plastic fuel tanks, such as Ohlssons,
Super Cyclones, Forsters, and Browns, will suffer major damage
to their tanks from the additives in today’s auto gasoline.
However, Coleman’s stove and lantern fuel is available in
Wal-Mart’s sporting-goods department. It’s similar to “white gas”
in all of its characteristics.
As for “70-weight” oil, for a long time that old-time, highviscosity
lubricant was nearly unobtainable. But I learned from
my old pal Zach Allerton (New Castle, Pennsylvania) that autoparts
dealers (such as AutoZone) carry Kendall’s Nitro 70 engine
oil, and that’s just like the stuff we used in model-airplane fuel in
the 1930s and 1940s!
A further problem with old-time model engines—especially for
RC Assist flying—is the spark-ignition system. The circuits we
used 60 years ago were exceedingly troublesome for a variety of
reasons that I won’t try to detail here. When they did work, they
produced considerable radio-frequency (RF) interference. That
often made it impossible to control an RC model while its engine
was running.
But in 1980, Floyd Carter devised a transistorized ignition
circuit that eliminated practically every difficulty connected with
flying models powered by spark-fired engines. Since then he has
sold hundreds of his “TIM” modules. They’re compact,
inexpensive, and highly reliable. They also reduce RF noise to a
bare minimum.
I’ve mentioned Floyd Carter’s TIM modules before, but he
recently moved his Aero Ply Research facilities to a new location:
87211 Louvring Ln., Eugene OR 97402; Tel.: (541) 338-4355; Email:
[email protected]. MA
66 MODEL AVIATION
02sig3.QXD 12/22/04 1:21 PM Page 66
Edition: Model Aviation - 2005/02
Page Numbers: 65,66
Edition: Model Aviation - 2005/02
Page Numbers: 65,66
Joe Wagner
T h e E n g i n e S h o p
212 S. Pine Ave., Ozark AL 36360
The new SuperTigre G-61 ABC. Its ringed G-75 “big brother” is
externally identical but 1 millimeter taller.
Large molded-plastic engine mounts need surface truing before
use. A big “mill file” ensures flat mounting areas.
New RCV91-CD rotary-sleeve-valve four-stroke is roughly the
same overall size as an O.S. .60 two-stroke but 4 ounces heavier.
Wal-Mart and AutoZone can provide fuel ingredients for RC
Assist fliers of Old-Timer models with spark-ignition engines.
SUPERTIGRE engines are back! They originated in Italy in 1948
and quickly made a winning reputation for themselves in European
power-model competition. A worldwide demand followed. And 20
years later, SuperTigre developed the first aluminum-brass-chrome
(ABC) model engines. The company has been manufacturing and
improving those ever since.
Today’s new SuperTigre engines are being made in China. The
overall quality of their materials and construction is at least 96% as
good as the earlier Italian-made engines—and the new prices are
astonishingly lower.
I acquired two of the larger RC SuperTigres last summer: a
G-61 ABC and a G-75 of the ringed-piston type. (The G-61 is
also available with a ringed piston.) They are so much alike that
it’s difficult to tell them apart visually.
They use exactly the same mounting dimensions. The G-75 is a
mere .040 inch taller than the G-61 and weighs roughly one-third of
an ounce more (26.53 for the G-61 and 26.88 for the G-75). However,
the G-75 is significantly more powerful. It certainly ought to be, with
23% greater displacement!
Both of my new SuperTigres started quite easily by hand from the
first try. The G-61 especially impressed me because I don’t
particularly enjoy the typical “tight squeak at Top Dead Center
(TDC)” feel of most ABC- and aluminum-brass-nickel (ABN)-type
model engines.
Some of those I’ve recently tested required warming their heads
for a few minutes with a heat gun to loosen the piston-to-cylinder fit
at TDC enough to make initial starting possible. I had no such
problems with the SuperTigre ABC. Its piston is fitted rather snugly
Aero-Ply TIM module, three-cell Ni-Cd pack provide reliability in
operating old-time spark engines. No “booster battery” needed.
in its bore at the top of its stroke—but not excessively so. Even at 60°
ambient temperature, I could easily flip the propeller by hand and
obtain immediate starting.
I’m not really surprised, though. SuperTigre has been making
ABCs for more than 35 years. By this time the company obviously
knows precisely how to optimize the fits.
SuperTigre provides plenty of useful documentation with its
engines. A “generic” instruction booklet covers all of the company’s
engines, from the G-34 to the G-2300. Clearly labeled photographs
and line drawings illustrate correct installation.
There is also a two-page troubleshooting “logic diagram” that lists
all major possible causes of engine malfunction. In simple language
this diagram tells how to overcome the problems. Recommended
propeller sizes and fuels are specified in this booklet too.
Each SuperTigre engine comes with a folder of exploded views:
one of the particular-size engine itself and the other of its carburetor.
In these drawings, all of the individual parts are identified and listed.
That will make ordering replacements easy and accurate. The folder
also provides complete engine mounting dimensions.
SuperTigre even supplies a sizable sheet of company logo and
spectacular tiger decals with each engine! Everything I’ve mentioned
comes neatly packaged in a protective foam-compartmented box.
Some assembly is necessary, but the only item that might prove a
trifle bothersome to install is the brass nut which retains the
carburetor’s clamping bolt. Don’t use long-nose pliers to tighten this
nut! There’s not much clearance space around it, and pliers will
inevitably slip and deform the soft brass. Even if you have to make the
tool yourself, use nothing but a small open-end wrench (or a metric
socket) on this nut.
I did have some trouble setting up the two SuperTigres for testbench
break-in and running; they wouldn’t fit conveniently in any of
my universal test mounts. Instead, I bought a big molded-plastic radial
mount that was the proper size to fit the SuperTigres. That was so I
could install it on a specially made hardwood fixture containing a fuel
tank and a throttle pushrod arrangement. (I described and showed my
custom test stand design in an earlier column.)
But when I removed the radial mount from its plastic bag, I
immediately saw that its mounting surfaces were far from smooth and
flat. That was the result of shrinkage that occurs when the molten
injection-molded plastic cools. (There’s no way of avoiding this,
especially in areas with thick cross-sections.)
Flat mounting surfaces—on the engine-beam tops and the rear
surface that contacts the firewall—are essential for reliable, lowvibration
engine operation. To correct the uneven-surface problem, I
clamped my new plastic radial mount firmly in a workbench vise and
carefully filed the mounting surfaces flat with a big, sharp-toothed
mill file.
(Files do get dull, as do any cutting tools, and then they are as
unsuitable for doing quick and accurate work as dull knives are. New
files don’t cost much, and they make the job much faster and easier.)
Mounting the SuperTigres to my filed-flat radial mount
provided a good opportunity for me to try a new tool: Tower
Hobbies’ Dead Center Hole Locator. It’s a most ingenious device
for accurately locating engine mounting-hole positions—in beammounting
lugs and in models’ firewalls.
This hole locator is much easier to use than to describe. It has a
small drill bit at the end of a long, thin, spring-loaded shaft. A
knurled knob at one end of the tool is used to manually rotate the
drill bit. The other end terminates in a conical guide. That centers
the bit precisely in an engine lug’s mounting hole while the bit is
being turned, making a “pilot hole” to accurately locate the
mounting-screw positions.
I discard the self-tapping engine-mounting screws that come
with most of the molded-plastic radial mounts. They are tough to
install and even worse to remove. Instead, I use my drill press to
make tapped holes for standard socket-head machine screws.
Doing the job that way takes only slightly longer to set up, and it
saves far more time—and frustration—when installing and
removing the engine-attachment screws.
I acquired another big, new engine that needs a specially made
test mount before I can test-run it: the RCV91-CD, which is
RCV’s latest crankshaft-drive four-stroke. I greatly admired the
earlier 58-CD, and I expect its “big brother” to run just as well.
I’ll report further on this engine in the next column—and the
special test-mount design I’ve come up with to simplify the job of
test-running today’s crop of big model engines.
Although almost all spark-ignition model engines went out of
production more than a half-century ago, a surprising number of
them have survived and are in good working condition. And
flying the classic FF designs of yesteryear with antique power
plants has become fairly popular—especially via “RC Assist.”
(That eliminates most of the cross-country chasing and treeclimbing
that used to be such an unpleasant but inescapable part
of Gas-model FF activities.)
Two aspects of operating old-time spark engines nowadays
have been presenting problems, one of which is fuel. The original
“standard formula” was three parts of “white gas” and one part of
“70-weight” nondetergent motor oil, but you can’t find either of
those at gas stations anymore.
Today’s automotive gasoline isn’t good for use in old-time
model engines. For one thing, its octane rating is much higher
than that of “white gas,” which can make for difficult starting. For
another, model engines with plastic fuel tanks, such as Ohlssons,
Super Cyclones, Forsters, and Browns, will suffer major damage
to their tanks from the additives in today’s auto gasoline.
However, Coleman’s stove and lantern fuel is available in
Wal-Mart’s sporting-goods department. It’s similar to “white gas”
in all of its characteristics.
As for “70-weight” oil, for a long time that old-time, highviscosity
lubricant was nearly unobtainable. But I learned from
my old pal Zach Allerton (New Castle, Pennsylvania) that autoparts
dealers (such as AutoZone) carry Kendall’s Nitro 70 engine
oil, and that’s just like the stuff we used in model-airplane fuel in
the 1930s and 1940s!
A further problem with old-time model engines—especially for
RC Assist flying—is the spark-ignition system. The circuits we
used 60 years ago were exceedingly troublesome for a variety of
reasons that I won’t try to detail here. When they did work, they
produced considerable radio-frequency (RF) interference. That
often made it impossible to control an RC model while its engine
was running.
But in 1980, Floyd Carter devised a transistorized ignition
circuit that eliminated practically every difficulty connected with
flying models powered by spark-fired engines. Since then he has
sold hundreds of his “TIM” modules. They’re compact,
inexpensive, and highly reliable. They also reduce RF noise to a
bare minimum.
I’ve mentioned Floyd Carter’s TIM modules before, but he
recently moved his Aero Ply Research facilities to a new location:
87211 Louvring Ln., Eugene OR 97402; Tel.: (541) 338-4355; Email:
[email protected]. MA
66 MODEL AVIATION
02sig3.QXD 12/22/04 1:21 PM Page 66