Radio Control Jets - 2009/02

I HAD an opportunity to fly a Composite-
ARF Flash last fall. Neat airplane! Gerry
Kerr Jr. attended the Spiderman Jet Rally
with a new Flash, fresh out of the shop and
ready for me to wring out. We arrived a day
early to get in some flying, and I had fun
with his new aircraft—that was, until he
realized how good it was and then he
wouldn’t let go of the sticks.
The Flash is a proven design from
Composite-ARF that’s been around for a few
years. It is an excellent high-performance
sport jet.
The model is of painted-in-the-mold
composite construction, typical of all
Composite-ARF designs. It has a simple onepiece
wing spanning 64.5 inches—just right
for 19- to 28-pound-thrust turbines. The
overall length is a healthy 81.5 inches, so the
Flash is not tiny. It is a perfect size for this
class of hot rod.
Composite-ARF claims that the Flash
weighs roughly 21-23 pounds empty, and,
depending on how you load it up with
options, that figure is realistic. The jet is
available in colors ranging from basic white
to colorful sport schemes, and it is even
available in military paint, including Blue
Angels livery.
Full details, including price and a listing
of Composite-ARF representatives, are on
the company’s Web site, which you can find
in the source listing at the end of this column.
Gerry’s model started life as a basic white
Flash, to which he added simple black trim.
Power is supplied by a SimJet 2300, and his
retracts are equipped with Pro-Link struts.
The fuel tanks in the aircraft consist of the
main fuselage tank that holds 2.2 liters of fuel
and a wing tank accommodating
approximately a half liter. That’s plenty of
onboard fuel for this size model.
Flying the Flash, I noticed two things
while taxiing out for takeoff. The main
landing gear has a wide track, and the
stiffness of the Pro-Link struts echoes every
bump in the runway through the hollow
composite wing (one of the nuances of
trailing-arm link struts when pulled full
vertical). The wide-track main gear makes
for excellent handling on takeoff and landing
rollout. Sweet!
In the air, the Flash performs as any sport
jet should—fast and smooth. These are longawaited
characteristics.
The recommended setup from
Composite-ARF was in place for the test
flight. I didn’t like it and neither did Gerry. It
can best be described as a setup you would
expect to have on a 3-D-capable, propellerdriven
airplane—plenty of throw with ample
exponential. It resulted in roll rates that
became progressively ridiculous for a jet and
an elevator that could get you into trouble
fast if pushed too far.
We changed the setup to a more
conventional arrangement, with reduced
throws and a slight amount of exponential.
This turned the Flash into a smooth-flying
model with some great aerobatic
capabilities. I am sure that exploring the
wild rates would be interesting, but I only
had three flights, and a smooth setup better
fit my flying style.
Also included in this column:
• The dead-stick landing
I like the wing on the Flash for
aerobatics. Whether I was pulling or pushing
the elevator, it felt good and locked in. I was
as comfortable doing outside loops as I was
with inside loops. They were consistent
either way.
Rolling maneuvers were good, with
adequate knife-edge holding capability
(speed helps), but even at moderate cruise
speeds, slow rolls and point rolls came
easily with good authority in knife-edge
flight.
The real test for any jet model is slow
flight. The Flash passed this test, but do not
mistake it for a trainer. It is a 200 mph hot
rod, but it is honest. The landing approach
without flaps is flat, which is a sign of a
clean airframe, but lower the flaps and it
slows down well.
The flaps are hinged on the bottom, with
the top LE extending forward of the hinge
line. This results in the top LE of the flaps
extending above the top surface of the wing.
The design is similar to spoilers, and it
works.
The descent angle on landing is pleasant;
it bleeds speed off quickly, making landing
much easier. The final flare, with the
recommended CG, is consistent and sweet.
The Flash is an enjoyable, highperformance
sport jet. Good job,
Composite-ARF. Thanks, Gerry, for
sharing your new hot rod with me for a
couple of fun flights.
One thing we still have to contend with—
even with jet models—is a dead-stick landing.
Our modern turbines are reliable, but they still
occasionally fail for sometimes inexplicable
reasons. Last year I experienced one flameout
on my turbine aircraft, and it reminded me of
the difficulty in performing a successful deadstick
landing.
Achieving a dead-stick landing depends on
three things: how quickly we identify the loss
of power, the energy available in altitude and
airspeed, and how the pilot handles the
situation. I was lucky. My flameout situation
was well within my skills, and I accomplished
a successful landing.
Let’s discuss that dead-stick situation.
Identify quickly when a turbine shuts down.
My shutdown was easy to detect: a beautiful
blue sky marked by the dreaded one-second
smoke trail. Kerosene hitting hot metal with
no fire means no more power.
Not all turbine-power losses are that easy
to identify. How does one recognize a
flameout? That’s a tough question.
I am a paranoid pilot. When my airplane
fails to perform at the speed I expect it to,
based on throttle position and angle of flight, I
perform a check. I level the wings, initiate a
mild climb, and open the throttle. If it doesn’t
accelerate as expected, I know I have a
problem.
Okay, so we believe the turbine has flamed
out. Now what? That depends where the
airplane is, relative to the runway, and the
energy available in airspeed and altitude.
The pilot must quickly react to this
complex situation and set up a landing
approach. My instinct is to initiate a climb,
converting airspeed to altitude, while deciding
on my first turn to the chosen landing point. I
express it this way for a reason.
If you’re in a downwind leg, it’s easy to
set up a landing approach. But what if the
flameout occurs just as you’re approaching the
start of the runway at 150 mph? How are you
going to get back to the runway? That’s a
tough call. Initiating a climb will give you a
brief moment to develop your plan, while
converting airspeed to altitude and increasing
your options.
Depending on the airplane, I know of three
options at this point. One is to pull up, execute
a 360° turn, and land on the runway; this is
possible only with a low-drag airplane.
A second option is to glide past the
runway, turn back with a 180° turn, and land
downwind. That’s tricky, but with most jet
models it can be done.
The third option, and one I have used often
with ducted-fan models (back when dead-stick
landings were common), is to perform a sharp
turnout and then reverse the turn direction and
head back to the runway. Turn to the runway
heading as you’re flaring to land, and extend
the landing gear at that time (and not a
moment sooner).
The landing gear and when you extend it
are two of the most powerful tools you have
when performing a dead-stick approach.
Think of extending the landing gear in the
same way a sailplane pilot thinks of the
spoilers.
When the spoilers are extended, the
sailplane will lose lift because of the increased
drag and descend quickly to the landing point.
Extending the landing gear does a similar
thing for the jet pilot.
We want the landing gear extended only
shortly before contact with the runway; any
sooner than that will take away precious
energy we may need to glide back to the
runway. I try to aim slightly high and then
extend the gear on runway heading only when
I feel I have the threshold made.
If you find yourself needing a little extra
float because the altitude is running out before
the runway is beneath you, add roughly 15° of
flap. That is enough to get additional lift
without producing a large drag increase. I use
this tip often if I am late on my final turn and
running out of altitude and ideas. It is my last
chance to find some lift, but it also keeps me
busy flying the airplane.
To summarize my philosophy of landing
without power: manage the energy of airspeed
and altitude; make it back to the runway; or
accept a controlled landing off field, but
expect at least some minimum damage.
Never extend the drag devices—landing
gear or flaps—until the runway is under the
model. One final note: if you’re flying low
and slow with no runway under or in front of
the airplane, this also means that you have no
energy and no options. What are you
thinking?
I know these few words barely touch on
this subject, but I hope it gets you thinking
about what you can do when faced with a
flameout. Try this mental exercise: watch a jet
flight and think how you would handle a
flameout from different positions during the
flight. Mental practice helps.
My brother Bill and I used to discuss this
often when we flew ducted-fan models. I only
have two off-field landings with ducted-fan
aircraft to my credit. They both happened
when I was low and slow and had no options.
I put the airplane in jeopardy before the
engine quit.
Now that’s enough discussion. Let’s get
back to flying. MA
Sources:
Composite-ARF
852 2153-9085 (Hong Kong)
www.composite-arf.com.hk