The innovative YS I7ODZ CDI engine
 «< Radio Control Aerobatics Eric Henderson
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The innovative YS |/0DZ CDI engine
THE WORLD OF precision Aerobatics
often gives birth to leading-edge products.
There is a never-ending search for aerobatic
design that demands ever more precise
control responses, maximum vertical power,
and structural strength for the least weight.
In many instances, I have been lucky
enough to own and use these latest and
greatest RC products. They tend to be
somewhat high-tech and a bit expensive.
Clearly, it is not possible to use or test
everything that is out there, Perhaps if the
AMA or MA had a paradigm mission shift
toward being a consumer guide or
something similar, more products could be
examined in greater detail.
However, product evaluations are not
this column's direction or purpose, so we
have to pursue other avenues by which to
gain insights into the hot products. In many
cases, that can be observation at events such
-- W> TE. as contests. Good material can be gathered
7. pe for inclusion in the column from competitor
EUPHORIA = ‘ “o and vendor interviews.
cenlual Halles ——= The good news is that some avid
h supporters of the Pattern world regularly
contribute new developments; they are
“shadow columnists,” if you will.
Sometimes it is via a letter to the column or
a more detailed and concerted effort. These
people are often sponsored pilots, but that is
Above: Troy Newman at the 2008 Nats/Team Trials with his caller, Terrance Brown.
Troy used two Oxai Euphorias with YS electronic-ignition engines.
Right: To control the glow plug’s spark, a sensor in the YS 170DZ’s
backplate lets the computerized ignition module know where the
crankshaft is and how fast it is turning.
Below: The preproduction YS 170DZ CDI fuel-injection engine
with electronic ignition added. Several pilots besides Troy used
this power plant at the 2008 Nats.
|| aT"
the primary reason why they get great early
access to wonderfully new and creative
products or Pattern-specific systems.
I have known these pilots/contributors
for decades, and I have learned to trust them
to give me the straight scoop. They write to
me and I get to lay it all out for you, the
One such contributor is Troy Newman: a
a A ‘ strong FAI pilot whose career is simmering
me Ee ' just below that of the current world-team
ón * ' | members. He had been flying some
interesting airplanes, radios, and engines up
The 170DZ CDI looks like a typical glow burner from above; the
only difference you will see is a different connector to where the
glow plug used to be.
until and at the 2008 AMA Nats. in which he
placed in the top eight.
This month 1 will feature the innovative YS
170DZ CDI four-stroke, supercharged
engine. The “CDI” designation tells us that
the engine has a spark-plug ignition system.
It is interesting, because even though this is a
spark-ignition engine, it uses methanol
instead of gasoline. (Methanol is probably
better described as regular glow fuel.)
Let's start with what Troy is flying. It is
an aerobatic biplane called the Euphoria,
which was designed by Quique Somenzini
(the current F3A World Champion) and is
produced by Oxai Models, The large model
has a lot of wing and frontal area. It needs a
big engine to overcome the drag of two
wings and pull it through the FAI
Troy is a Team JR member, and he uses
the new JR 12X (native) radio system. The
term “native” indicates that the radio is
dedicated to DSM (Digital Spectrum
Modulation) technology and does not have a
72 MHz module option.
Central Hobbies, which is a well-known
supplier with a high degree of focus on
Pattern flying, provided all the special engine
hardware and accessories. The company also
let Troy use the best in ball-race clevises and
control connection accessories. There is no
slop in any of his control hookups. His YS
engine burns Cool Power fuel from Morgan
Fuels and turns a 19 x 11 APC propeller that
was specially designed for the 170 CDI.
The YS 170DZ CDI is currently a
prototype that YS is using to test its new
ignition system. This engine was unveiled at
the 2008 FAI Team Trials, held in Muncie,
Indiana. |
An electronic ignition system has been
added to the latest YS 170DZ. There is no
glow plug; instead, a mini spark plug is
driven by a sensor in the rear of the
backplate. This is similar to the well-known
ignition system used in the popular gasoline
engines that you find in Giant Scale
airplanes today.
the “spaghetti.”
The 170DZ originally weighed 32
ounces, and the CDI ignition system added
4.5 ounces. All the power plants that Troy
flew at the AMA Nats/Team Trials in July
2008 were converted from the standard
production YS 170DZ.
New parts were added to these engines
to allow conversion to the ignition system.
The spark plug is designed to fit a glow-
plug hole and uses the same thread. A
sensor, which is buried in the 170DZ's
backplate, takes the timing information
from a magnet in the rear rotor disc valve.
This part is driven directly from the
The sensor sends the rpm data to the
electronic ignition module that performs
two functions. First, it senses the current
rpm and determines the proper advance or
retardation timing for the spark.
Second, because the 170DZ is a four-
stroke, the module causes an ignition spark
every second trip the piston takes to the top.
This engine basically works like a Desert
Aircraft DA-50, except that it runs on glow
fuel and is a four-stroke.
This system provides several benefits.
The engine runs based on its ignition
timing, which is related to the rpm.
Normally, with a glow engine, the
compression of the gases and glow element
combine to make a big boom when the
pressure is just right. The engine ignition-
point timing is set by a given heat load,
glow plug, and compression.
In the YS 170DZ CDI, the ignition point
is electronically determined. This prevents
the preignition situation you can get with a
slightly lean setting on a glow plug. If a
non-CDI version is overloaded (with too big
of a propeller), to below 7,500 rpm for the
purpose of this example, the engine will
start to overheat and change the timing of
the engine.
With electronic ignition, we can load the
engine down with larger propellers and it
gets no preignition or detonation
(knocking). Troy ran a new 19 x 11
propeller that APC (through Landing
The sophisticated YS 170DZ CDI uses a complex pump and
injection plumbing. Now you can add an insulated ignition lead to
Products) designed specifically for the YS
ignition engine.
The mighty YS will turn this huge
propeller at 7,300-7,400 rpm at full power.
The raw “vertical grunt” from this setup is
awesome. From an FAI point of view, using
these larger propellers at lower rpm has the
desirable benefit of reducing the complete
airborne system’s noise.
The next benefit is that the 170DZ CDI
can idle extremely reliably at low rpm.
Depending on your setup, you can idle it as
low as 1,200 and up to 1,400 rpm. It is
tremendously smooth. There is no need to
worry about dead-stick engine-outs from the
idle being too low,
It is amazing how much down-line
braking you can get from a four-stroke-
driven 19-inch propeller when the idle does
not speed up. This is a big benefit to a pilot
who is trying to fly constant-speed
maneuvers. The YS will be a powerful tool
in F3A Aerobatics.
When Troy started running this YS, he
used normal Cool Power 30% helicopter
fuel. It is the same stuff used in the glow
version of the 170DZ. After some
developments, the ignition system allowed
the use of much less oil to lubricate the
Morgan Fuels stepped up to the plate
with a contribution during testing. It made a
special 30% nitromethane, 5% all synthetic
oil fuel for this engine. Yup, that's 5% oil.
A benefit there is that the traditional smoke
trail is now gone.
The engines seem to run a bit smoother,
and there is little or no oil to clean off the
bottom of your model. Please note that this
oil package is developed around the
ignition-system YS and should not be used
on normal glow engines.
You don’t need a glow-plug battery to
start the model. Troy values his fingers and
chose to start the engine with an electric
starter. To do so, add fuel, turn on the
ignition, and spin the crank with a starter;
the engine starts immediately. It runs
smoothly at a visibly slow 1,400 rpm idle.
January 2009 111
This is amazing technology that is coming
soon from YS Engines.
The YS 170DZ CDI system is still in
testing, and we are learning more and more
about it. Therefore, there is no firm release
Troy could not be more pleased with
this system’s performance in his airplane at
the AMA Nats. It enabled him to qualify for
the finals and advance to an eighth-place
He was competing against some of the
best pilots in the world. The finals featured
seven pilots who had been to the FAI World
Championships, two World Champions,
and three World Championships finalists.
Being competitive with pilots of that caliber
was in no small part because of the YS
170DZ CDI’s performance.
Troy said that competition at this level is
a combined effort. He wanted to say a big,
public “Thank you!” to his caller, Terrance
Brown, for all his help.
51ce, Max 9000 RPM, Idle 1370 RPM
Weight 3.3lbs, Includes Standoffs & Muffler
Only $399.95
There you have it: a thrilling new engine
as seen through a top competitor’s eyes.
Maybe each of us can have one someday.
We can only hope. MA
YS Parts and Service
(775) 267-9252
Oxai Models
- (800) 723-5937
Central Hobbies
(800) 723-5937 (orders only)
(406) 259-9004 (for technical information)
Morgan Fuel
(800) 633-7556
Landing Products
(530) 661-0399
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