October 2009 129
[[email protected]]
Radio Control Jets Jim Hiller
Also included in this column:
• Airworthiness notification
preferences
• Father-and-son issues
How to choose the appropriate jet engine fuel
Ben Bulden Jr. is the proud pilot of this JetCat P80-powered
Kangaroo. He is proving to be a safe jet pilot who knows how to
have fun flying fast movers.
Ron Ballard’s Mibo A-10 has two Wren 160 turbines. You need
to see it up-close to appreciate the attention to detail that Ron
put into this model.
The Buldens of Lima, Ohio, are father, Ben, and son, Ben Jr. Dad’s Rookie II suits Ben
Sr.’s aggressive flying style. Both are enjoyable to watch.
ONE ISSUE THAT is regularly brought up
is what type of fuel to use. I have burned Jet-A
purchased at airports, low-odor kerosene from
hardware stores, and kerosene from the pump
at a gas station. All have run fine in our
turbine engines.
My fuel of choice is pump kerosene, with
a red dye added for a tint. A gas station 3
miles from my house, on the way to the field,
carries kerosene. It’s inexpensive compared to
other sources, and convenience rules on this
selection.
The red tint greatly helps me check fuel
levels inside the airplane, even through
composite tanks. I have been awarded a pink
Jet Central hat to match my red kerosene.
My next choice (also a good one) is lowodor
kerosene from hardware stores. This is
usually clear and the odor is reduced, not
eliminated, but it is still a plus if you store
your models indoors after a flying session.
The cost of this kerosene tends to be the
highest, and its availability is seasonal at best
in my area. This availability issue was my
prime reason for switching from this product;
it’s not available in the summer.
My last choice, which is especially
convenient when flying from a local airport, is
Jet-A fuel. Its cost is moderate—usually a
dollar more per gallon than pump kerosene. A
large-mouth container is necessary, because
aircraft fueling nozzles are larger in diameter
than those used for automobiles. A funnel can
work in a pinch.
Jet-A has a strong odor. I would store my
models in the barn for a week after a flying
session to air them out before taking them to
my basement workshop.
I did experience a couple instances of
algae growth following long-term storage
(more than three months) of Jet-A—even
what was left in the model.
All three sources of kerosene were
reliable. My turbines ran the same regardless
of the fuel used, so make a choice based on
your situation. My preference for pump
kerosene over other sources of fuel is pure
10sig5.QXD 8/21/09 12:32 PM Page 129
convenience, both for purchase and storing
the model following the flying session.
A related issue is the oil required to be
mixed with your fuel. The decision seems so
complex, but it shouldn’t be.
Follow your turbine manufacturer’s
recommendations. If they are to use turbine
oil, do so at the percentages instructed. The
makers are experienced with their turbines
and know what they need.
I ran turbine oil for years and used most
brands (Mobil, BP, and AeroShell), with no
bearing or carbon buildup issues related to a
particular selection. Good and bad have been
said about each type through the years, but I
don’t believe that any brand of oil has a
significant advantage over another. I always
based my brand selection on availability.
I have recently switched to Mobil DTE
Light: an alternative to turbine bearing oil.
Both manufacturers of the turbines I am
running—Jet Central and Wren—recommend
the Mobil as an alternative to turbine bearing
oil, which was the most important
consideration before switching. I would not
run Mobil DTE Light in a turbine if a turbine
manufacturer did not endorse its use.
Again, my switch was based on personal
reasons. Since I now have access to a paved
runway at a local model field, I no longer
frequent airports with turbine oil on the field.
The nearest airport is 15 miles away in the
opposite direction from my flying site—not so
convenient.
I purchased my Mobil DTE Light in a 5-
gallon container from an industrial supplier
that is located just 4 miles from our flying
site; you can’t beat that for convenience.
I mix the Mobil DTE Light to the same
percentages as are normally called for. In the
case of my Wren and Jet Central turbines, it’s
21/2%, or 1 quart, per 10 gallons.
On the topic of operating issues, I was
recently reminded just how damaging the high
airspeeds we operate our jet models at can be
to an airframe. I have owned my Bob Violett
Models (BVM) BobCat XL for roughly a
year-and-a-half and put approximately 150
flights on it before an incident occurred.
While flying an aggressively fast flight,
the model took a large bug strike to the LE
between the tailbooms that damaged the paint
and epoxy finish underneath on the balsa LE.
It was a small knick, close to 1/8 inch in
diameter.
What happened as the day progressed
surprised me. Two flights later, that small
knick had opened up to more than 1/2 inch in
diameter and down into the balsa LE
approximately 1/8 inch. It was time to quit for
the day and repair; I didn’t want to lose this
fun machine.
Close inspection of the LE revealed that
no fiberglass cloth was used on the centersection
area of the wing; only an epoxy finish
resin was used. Both outer wing panels have
fiberglass cloth, but I don’t know why the
builder missed this on the center-section; it
makes a difference at our speeds.
I repaired the LE with a mix of epoxy and
cabasil, sanded smooth and flush. I changed
my mind about repainting the damaged LE; it
needed additional strength. I used a layer of
aluminum tape to reinforce the area and finish
it similar to the polished LE cuffs on some
full-scale jets. Besides, the metal finish
allowed me to add rivet detail.
So far, the repair has held up to numerous
bug strikes with no problems. This example
proves that our jets fly at speeds that put
considerable aerodynamic stress on the
airframes.
I have witnessed two airframes
disintegrating during the first few flights for
the same structural failure: the fuselage failing
at the inlets, allowing the aircraft’s nose to
break off. Both were ARFs of fiberglasscomposite
construction and appeared well
built, but they had large canopy hatches. This
left little structure above the inlet area forward
to support the large fuselage nose section
ahead of the inlets.
Both models failed at high speeds,
resulting in catastrophic breakup of the
airframes. As the nose separated, the turbines
shut down, probably because the batteries
disconnected since they were located forward
in the fuselage section that separated, and the
airframes tumbled to the ground.
Okay, what did they really have in
common? The designers/manufacturers/pilots
lacked appreciation of the huge air loads
imposed at the speeds we fly?
130 MODEL AVIATION
In one case, the manufacturer laid up a
special light fuselage with less fiberglass
cloth, and the new owner had his input to
this impending failure. He was proud of
his new, larger-than-recommended
turbine installation. These two factors
combined, resulting in the loss of a
beautiful airplane.
We regularly fly modern jets that are
capable of achieving 200 mph level flight
speeds, but these are not always the
proven, tried-and-true airframes to which
we have become accustomed. The
wonderful world of prepainted ARFs and
the rapid growth of manufacturers and the
rate at which they “develop” new
airframes should be a warning.
I recommend that the companies issue
airframe directives when problems
develop in the field; they assist the
modeler in solutions. BVM has done this
for years. Check out the company’s Web
site for information about all of Bob’s
models; the experiences shared provide
the pilot with knowledge for successful
long-term operations of BVM aircraft.
Another company that now provides
this service is Bruce Tharpe Engineering
(BTE), which markets the PST Reaction
54. Great job! It is appreciated.
We modelers need to stay informed
about the problems that can occur, and the
manufacturers need to provide this service
of disseminating information. It greatly
enhances the ownership experience.
A great sight at Midwest jet events is
Ben Bulden and his son, Ben Jr., flying
together. The Bulden team is from Lima,
Ohio, and each has his own jet. This is a
great father-and-son team.
Dad’s airplane is the impressive Red
Bull Rookie II, powered with a JetCat
P120 turbine—lots of power. And he
knows how to fly it low and fast.
Ben Jr. is 14 years old and proving to
be a terrific jet pilot. He has four years of
flying experience, and he pilots his jet
extremely well. He has grown up flying
with his dad and now has his own
Kangaroo with a JetCat P80.
That’s a powerful combination for this
young pilot, but Ben Jr. needs it to keep
up with Dad. He knows his limits, flies
within them, and is a pleasure to share the
skies with at the jet meets.
Keep the family flying, and see you
guys at the next jet meet. MA
Sources:
BVM
(407) 327-6333
www.bvmjets.com
BTE
(800) 557-4470
www.btemodels.com
Jet Pilots’ Association
(904) 318-7171
www.jetpilots.org
Edition: Model Aviation - 2009/10
Page Numbers: 129,130
Edition: Model Aviation - 2009/10
Page Numbers: 129,130
October 2009 129
[[email protected]]
Radio Control Jets Jim Hiller
Also included in this column:
• Airworthiness notification
preferences
• Father-and-son issues
How to choose the appropriate jet engine fuel
Ben Bulden Jr. is the proud pilot of this JetCat P80-powered
Kangaroo. He is proving to be a safe jet pilot who knows how to
have fun flying fast movers.
Ron Ballard’s Mibo A-10 has two Wren 160 turbines. You need
to see it up-close to appreciate the attention to detail that Ron
put into this model.
The Buldens of Lima, Ohio, are father, Ben, and son, Ben Jr. Dad’s Rookie II suits Ben
Sr.’s aggressive flying style. Both are enjoyable to watch.
ONE ISSUE THAT is regularly brought up
is what type of fuel to use. I have burned Jet-A
purchased at airports, low-odor kerosene from
hardware stores, and kerosene from the pump
at a gas station. All have run fine in our
turbine engines.
My fuel of choice is pump kerosene, with
a red dye added for a tint. A gas station 3
miles from my house, on the way to the field,
carries kerosene. It’s inexpensive compared to
other sources, and convenience rules on this
selection.
The red tint greatly helps me check fuel
levels inside the airplane, even through
composite tanks. I have been awarded a pink
Jet Central hat to match my red kerosene.
My next choice (also a good one) is lowodor
kerosene from hardware stores. This is
usually clear and the odor is reduced, not
eliminated, but it is still a plus if you store
your models indoors after a flying session.
The cost of this kerosene tends to be the
highest, and its availability is seasonal at best
in my area. This availability issue was my
prime reason for switching from this product;
it’s not available in the summer.
My last choice, which is especially
convenient when flying from a local airport, is
Jet-A fuel. Its cost is moderate—usually a
dollar more per gallon than pump kerosene. A
large-mouth container is necessary, because
aircraft fueling nozzles are larger in diameter
than those used for automobiles. A funnel can
work in a pinch.
Jet-A has a strong odor. I would store my
models in the barn for a week after a flying
session to air them out before taking them to
my basement workshop.
I did experience a couple instances of
algae growth following long-term storage
(more than three months) of Jet-A—even
what was left in the model.
All three sources of kerosene were
reliable. My turbines ran the same regardless
of the fuel used, so make a choice based on
your situation. My preference for pump
kerosene over other sources of fuel is pure
10sig5.QXD 8/21/09 12:32 PM Page 129
convenience, both for purchase and storing
the model following the flying session.
A related issue is the oil required to be
mixed with your fuel. The decision seems so
complex, but it shouldn’t be.
Follow your turbine manufacturer’s
recommendations. If they are to use turbine
oil, do so at the percentages instructed. The
makers are experienced with their turbines
and know what they need.
I ran turbine oil for years and used most
brands (Mobil, BP, and AeroShell), with no
bearing or carbon buildup issues related to a
particular selection. Good and bad have been
said about each type through the years, but I
don’t believe that any brand of oil has a
significant advantage over another. I always
based my brand selection on availability.
I have recently switched to Mobil DTE
Light: an alternative to turbine bearing oil.
Both manufacturers of the turbines I am
running—Jet Central and Wren—recommend
the Mobil as an alternative to turbine bearing
oil, which was the most important
consideration before switching. I would not
run Mobil DTE Light in a turbine if a turbine
manufacturer did not endorse its use.
Again, my switch was based on personal
reasons. Since I now have access to a paved
runway at a local model field, I no longer
frequent airports with turbine oil on the field.
The nearest airport is 15 miles away in the
opposite direction from my flying site—not so
convenient.
I purchased my Mobil DTE Light in a 5-
gallon container from an industrial supplier
that is located just 4 miles from our flying
site; you can’t beat that for convenience.
I mix the Mobil DTE Light to the same
percentages as are normally called for. In the
case of my Wren and Jet Central turbines, it’s
21/2%, or 1 quart, per 10 gallons.
On the topic of operating issues, I was
recently reminded just how damaging the high
airspeeds we operate our jet models at can be
to an airframe. I have owned my Bob Violett
Models (BVM) BobCat XL for roughly a
year-and-a-half and put approximately 150
flights on it before an incident occurred.
While flying an aggressively fast flight,
the model took a large bug strike to the LE
between the tailbooms that damaged the paint
and epoxy finish underneath on the balsa LE.
It was a small knick, close to 1/8 inch in
diameter.
What happened as the day progressed
surprised me. Two flights later, that small
knick had opened up to more than 1/2 inch in
diameter and down into the balsa LE
approximately 1/8 inch. It was time to quit for
the day and repair; I didn’t want to lose this
fun machine.
Close inspection of the LE revealed that
no fiberglass cloth was used on the centersection
area of the wing; only an epoxy finish
resin was used. Both outer wing panels have
fiberglass cloth, but I don’t know why the
builder missed this on the center-section; it
makes a difference at our speeds.
I repaired the LE with a mix of epoxy and
cabasil, sanded smooth and flush. I changed
my mind about repainting the damaged LE; it
needed additional strength. I used a layer of
aluminum tape to reinforce the area and finish
it similar to the polished LE cuffs on some
full-scale jets. Besides, the metal finish
allowed me to add rivet detail.
So far, the repair has held up to numerous
bug strikes with no problems. This example
proves that our jets fly at speeds that put
considerable aerodynamic stress on the
airframes.
I have witnessed two airframes
disintegrating during the first few flights for
the same structural failure: the fuselage failing
at the inlets, allowing the aircraft’s nose to
break off. Both were ARFs of fiberglasscomposite
construction and appeared well
built, but they had large canopy hatches. This
left little structure above the inlet area forward
to support the large fuselage nose section
ahead of the inlets.
Both models failed at high speeds,
resulting in catastrophic breakup of the
airframes. As the nose separated, the turbines
shut down, probably because the batteries
disconnected since they were located forward
in the fuselage section that separated, and the
airframes tumbled to the ground.
Okay, what did they really have in
common? The designers/manufacturers/pilots
lacked appreciation of the huge air loads
imposed at the speeds we fly?
130 MODEL AVIATION
In one case, the manufacturer laid up a
special light fuselage with less fiberglass
cloth, and the new owner had his input to
this impending failure. He was proud of
his new, larger-than-recommended
turbine installation. These two factors
combined, resulting in the loss of a
beautiful airplane.
We regularly fly modern jets that are
capable of achieving 200 mph level flight
speeds, but these are not always the
proven, tried-and-true airframes to which
we have become accustomed. The
wonderful world of prepainted ARFs and
the rapid growth of manufacturers and the
rate at which they “develop” new
airframes should be a warning.
I recommend that the companies issue
airframe directives when problems
develop in the field; they assist the
modeler in solutions. BVM has done this
for years. Check out the company’s Web
site for information about all of Bob’s
models; the experiences shared provide
the pilot with knowledge for successful
long-term operations of BVM aircraft.
Another company that now provides
this service is Bruce Tharpe Engineering
(BTE), which markets the PST Reaction
54. Great job! It is appreciated.
We modelers need to stay informed
about the problems that can occur, and the
manufacturers need to provide this service
of disseminating information. It greatly
enhances the ownership experience.
A great sight at Midwest jet events is
Ben Bulden and his son, Ben Jr., flying
together. The Bulden team is from Lima,
Ohio, and each has his own jet. This is a
great father-and-son team.
Dad’s airplane is the impressive Red
Bull Rookie II, powered with a JetCat
P120 turbine—lots of power. And he
knows how to fly it low and fast.
Ben Jr. is 14 years old and proving to
be a terrific jet pilot. He has four years of
flying experience, and he pilots his jet
extremely well. He has grown up flying
with his dad and now has his own
Kangaroo with a JetCat P80.
That’s a powerful combination for this
young pilot, but Ben Jr. needs it to keep
up with Dad. He knows his limits, flies
within them, and is a pleasure to share the
skies with at the jet meets.
Keep the family flying, and see you
guys at the next jet meet. MA
Sources:
BVM
(407) 327-6333
www.bvmjets.com
BTE
(800) 557-4470
www.btemodels.com
Jet Pilots’ Association
(904) 318-7171
www.jetpilots.org