Jet events bring out new and exciting products
Also included in this column:
• Looks can be deceiving
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Radio Control Jets Jim Hiller
Above: Bob Violett waits his turn to fly
his new Electra Jet powered with an
electric ducted fan—a great performance
package.
Right: Dwayne Woods’ gorgeous
Skymaster MB-339 spans 8 feet and is
powered by an AMT 400 with the electricstart
option. It’s a nice-flying setup.
Below: Jet Central’s new Turbo Prop,
complete with lifetime warranty, is based
on the Super Bee and turns a 26-inch,
two-blade propeller.
DURING THE SUMMER I attended three jet events in four
weekends; I love our flying season! The people involved in
setting up and running these events did a great job, and the sites
allowed for great jet flying.
The meets included the Bluegrass Jet Jam, the Flying Aeros
Jet Jam, and Jets Over the Heartland. The host clubs were
extremely involved. I definitely feel in the jet zone now!
The Bluegrass Jet Jam is organized by Mike Kirby and the
Southern Kentucky Model Aero Club (SKYMAC) at its own
flying field. The site has a 1,000-foot paved runway and the club
consists of a great group of guys.
The Flying Aeros event in Ohio was run by Joe Lewis and the
Flying Aeros Association at the Braceville Airport. That private
facility strongly supports aviation of all types, including an
Experimental Aircraft Association chapter and model aircraft.
The Jets Over the Heartland event in Indiana was run by Tim
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Redelman and the Winamac Aero
Modelers at another incredible flying site
dedicated to model aircraft.
I compliment our jet-modeling
industry for the strong support it gave
these events. Special kudos go to AMT,
JetCentral, and JetCat for helping fund
them.
Eric Clapp of JetCentral took the
company’s complete line of turbines to
Winamac, and they were nicely packaged
and complete for all to see. Sitting at the
end of the table was the new Turbo Prop,
ready for delivery.
JetCentral builds its Turbo Prop based
on the Super Bee core with a sweetlooking
turbine gearbox power package.
The complete unit weighs 5 pounds with
the starter.
The Turbo Prop turns a 26-inch, twoblade
propeller with the turbine running at
180,000 rpm. The setup is sold with all
the normal accessories, such as fuel pump,
ECU (electronic control unit), Hand Data
Terminal, fuel valves, and six-cell, 1400
mAh battery pack.
A few months ago I spoke with Felipe
Nieto of JetCentral about this Turbo Prop,
and he was proud at that time of how well
flight testing had been progressing. He
told me he would introduce the Turbo
Prop to market as soon as he was assured
it would be a reliable, strong addition to
the JetCentral line. (JetCentral turbines
carry a lifetime warranty.)
The movies Felipe showed me
included his Giant Scale aerobatic model
flying with authority yet displaying good
throttle response. The Turbo Prop should
make a strong addition to the JetCentral
lineup. For additional information about
this engine and JetCentral’s complete
lineup of turbines, visit www.jetartes.com.
Bob Violett flew his new Electra Jet at
Jets Over the Heartland. I hadn’t seen his
electric ducted fans fly for approximately
six months, and I compliment him on the
performance improvements.
The Electra Jet is an excellent
airframe. It’s well matched to the electric
fan power, and Bob knows how to show it
off. He has the skills to display extreme
flight with this model.
The battery options continue to
improve, and the Electra Jet has the room
to accept them. Although it lacks the
smell and sound of a turbine, it isn’t
deficient in performance. This model
would make a great jet for fields with
noise restrictions or when turbine flying is
curtailed because of drought conditions.
Information about the Electra Jet can
be found at Bob Violett Models’ Web site
at www.bvmjets.com.
The JR Spektrum systems have hit the
jet-modeling community in a big way. A
disappointing beginning has been
followed by many success stories. When
properly set up in a jet, this new
technology works extremely well.
During a rain delay at Jets Over the
Heartland Jeff Holsinger and Erik Meyers
held an informative seminar on this new
technology, explaining its operation and the
new terms and products with which we will
be dealing. They covered in detail how to
set up a JR Spektrum module in a JR 10Xseries
radio.
There are two important issues of
concern, one of which is that a reliable
voltage source is required. If the voltage
goes too low for merely an instant, the
computer-technology-based receiver will
reboot, leaving you with no control for an
extended period of time.
The other issue is antenna placement:
where it is located, its orientation, and how
many you have. Additional antennas or
receivers can be purchased to improve
difficult installations or boost signal
reception. A typical jet installation will
have two receivers: the primary with two
antennas and a remote with one antenna.
Jeff strongly recommends spending the
extra $25 for the Flight Logger, for peace
of mind. This nifty little device stays
plugged into the receiver to record fades,
frames, and lockouts, as well as serving as
an onboard voltage gauge for your receiver
battery.
Jeff explained that fade
occasionally surprised by some of
these models’ poor-quality workmanship,
questionable system layouts, and general
weakness of aerodynamic design. Because
it looks like a jet doesn’t make it equal.
Buyer beware!
One area to consider is flight-surface
installation, but what should you look for?
The three main issues to consider are how
solidly they are attached to the airframe,
how solid the control-horn attachment is,
and how rigid the airframe is. These issues
relate to the ability to handle flight loads
and flutter.
A firm, strongly attached control
surface must be able to handle the air
loads and servo loads without failing in
flight and causing loss of control. In
modeling we generally accept a rigid
installation—particularly the control
linkages—as an acceptable method of
containing flutter.
Notice that I did not write
“eliminating” flutter. The best control
linkage, best servo, and most powerful
batteries will not contain flutter if the
basic airframe itself is not rigid enough
not to flex and flutter.
Poor-quality glue joints in the TE spar to
wing skin, fin skin, or stabilizer skins have
resulted in the loss of many aircraft because
of airframe flutter. Take the time to inspect
this area of the model.
Another area to look at closely is flying
stabilizers. I love models with this feature.
They are simple, work exceedingly well,
and, in many cases, match the full-scale
model for scale purposes.
What should we watch for on these?
Understand that the flying-stabilizer loads
are greatly affected by the pivot point. If it is
too far aft, they will not want to stay straight
near the center. Your model’s hunting in
level flight could be caused by a pivot point
that is located too far aft.
It can be corrected by moving the pivot
point forward. A more common fix is to use
a stronger digital servo with rigid linkages to
combat these centering forces and forcibly
hold the stabilizer in position.
A flying stabilizer induces a load on the
servo in most designs. In all the F-18s I have
flown there has been a couple degrees
negative incidence when trimmed for level
flight. This position was held by the servo,
and in one case on a ducted-fan model that
servo wasn’t powerful enough.
I initially believed the model was tailheavy
because it climbed poorly when I
slowed it down. It took a couple flights
before I tried a different elevator servo, and
as simple as that the problem was cured. The
new servo was not rated as more powerful
than the original, but it had more power
when centering the surface, so it worked
better and fixed the model’s flight problems.
I hope this keeps you thinking about your
model’s setup so you can be successful.
Flying jets is fun and crashing