Micro-Flying - 2007/07

84 MODEL AVIATION
John Worth offers a heartfelt farewell to Dave Robelen
Micro-Flying John Worth | [email protected]
Right: The inside of the Dragonfly shows
the receiver, battery, motor, and linkages.
Sold at RadioShack, the flapping-wing RTF Dragonfly is a true ornithopter design with
a two-channel transmitter for motor and rudder control.
The Kyosho 2.4 GHz spread spectrum Cessna 210 Centurian is a 15-inch-span scale
model that weighs only 18 grams and comes factory finished.
Also included in this column:
• New Plantraco receiver
• RTF RC Dragonfly from
RadioShack
• The impact of spread spectrum
• Where to find more micro-flying
information
SHORTLY BEFORE press time I received
word that Dave Robelen, the regular writer for
“Micro-Flying,” had entered a hospital with a
very serious health problem that prevented him
from sending in his monthly column. Shortly
afterward I learned that Dave had died in the
hospital.
This was sudden, sad news. Dave had been
active with flying activities earlier this year
with his Bede BD-4 micro scale model
described in his January 2007 column.
Dave and I were friends for many years,
so I offered to provide a “Micro-Flying”
column for MA to ensure the continuity of
this subject for his readers. Dave and I often
shared micromodel information, and we
worked together a long time ago when we
were NASA employees at Langley Field in
Virginia. We also flew models there, and
when Dave was just a young kid I flew
there with his dad.
Dave and I had a great history together,
lasting from those early days to the present,
long after we went separate ways after leaving
NASA. I’m proud to carry on in his name with
his favorite subject: micro-flying.
(Editor’s note: For a look at Dave
Robelen’s amazing aeromodeling career, visit
the AMA Web site at www.modelaircraft.org/
museum/bio/Robelen.pdf to see his 20-page
autobiography or Google “David Robelen” to
see more of his aeromodeling contributions.)
New Plantraco Receiver: A significant
aspect of micro-flying is the steady advance
of technology that enables a growing
number of us to enjoy flying ever smaller
and lighter electric-powered RC model
aircraft. A major contributor to that
advancement is Plantraco of Canada.
Roughly a year ago the company
introduced the Carbon Butterfly: an 8-inchwingspan,
two-channel RTF that weighs
only 3.5 grams. Dave detailed this incredible
model in his March 2007 column, and many
have bought, flown, and enjoyed it.
Until Plantraco came up with the Carbon
Butterfly (and its predecessor, the balsaframe,
tissue-covered Butterfly), only a few
skilled micro fliers who built their own
models were able to fly anything so
lightweight. Now dozens and perhaps
hundreds have bought and flown the
Butterfly and/or the Carbon Butterfly.
Plantraco has gone a step further and
produced a new receiver that is similar to the
one in the Butterfly. It is designed to operate
with microservos, in contrast to the Butterfly
receiver that has a single magnetic actuator
to operate the rudder. The new receiver
offers a built-in speed controller for a small
brushed motor with gear drive for the
propeller.
The new servo receiver is $39.95. It’s
only 14 x 23mm—less than an inch long—
and weighs only 1.2 grams! Designed for
four channels, the receiver has three servos
for flight control surfaces (such as rudder,
elevator, and ailerons) and can control either
a brushed motor (with or without gears) or a
brushless motor.
For a brushed motor, the speed control
with a 2-amp capacity is built into the
receiver. An external speed controller needs
07sig3.QXD 5/23/07 10:35 AM Page 84
flight control surfaces, and a Li-Poly battery.
to be connected between the receiver and the motor to operate a
brushless motor.
The receiver needs only a single Li-Poly cell when a brushed motor
is used. Use a two-cell Li-Poly with a brushless motor.
The speed control provides two-cell power to the motor and onecell
power to the receiver. Sockets are on the receiver for plug-and-play
hookup—no soldering tiny, fragile wires.
As with the Butterfly, the receiver operates on 900 MHz.
Plantraco’s transmitter or the company’s Monolith modular accessory
can operate it.
The Monolith can be plugged into Hitec or Futaba 72 MHz
transmitters that have a trainer jack for a buddy box. The Monolith
provides the 900 MHz, with six user-selectable frequencies. With the
accessory disconnected, the transmitter reverts to its normal 72 MHz
operation. The Monolith costs $34.95.
You can get more details by visiting the Plantraco Web site at
www.plantraco.com.
Flapping Wings? A different kind of micro-flying, normally associated
with FF models, is the RTF RC Dragonfly, sold in RadioShack stores.
This $49.95 product has two channels for motor and rudder control.
The motor in this model flaps the wings to provide thrust rather than
a propeller. This true ornithopter design provides birdlike flight for as
long as 10 minutes between charges. It is only for indoor flying or if it’s
dead calm outdoors.
The Dragonfly performs well, especially when you add a gram or so
of nose weight to achieve smooth turning flight. It can be flown in a
room of roughly 12 square feet, and it can do figure eights nicely if the
room is 12 x 18 or 20 feet.
It needs little power and seems to fly best throttled back to provide a
gradual climb or level flight. The aircraft ROGs rises off ground well,
although it has no wheels.
The transmitter has a switch for beginner or advanced pilots. Of the
roughly half dozen fliers I know who have the Dragonfly, all seem to
prefer the beginner setting. The advanced setting enables turns to be
much tighter, but it makes for more erratic flight because it’s prone to
overcontrolling.
A surprising and nice feature is the smoothness of the throttle
control. The Dragonfly ranges from slower oscillations of greater wing
movement to faster and shorter strokes of wing movement.
Another pleasant surprise has been the aircraft’s ruggedness. It has
survived many impacts with walls and other obstacles without damage.
An extra set of wings is provided with each Dragonfly, but I haven’t
needed them—so far!
New Micro Spread Spectrum: In the past year we saw a great impact
on the nature of RC flying when spread spectrum equipment operating
at 2.4 GHz was introduced. Practically overnight a large number of
people flying the new equipment have not had to be concerned with
frequency control.
Turning on the equipment and following the instructions, people
can fly without interference to others or themselves. This has greatly
reduced worries about interference in backyard or parking lot flying
situations.
In the past year relatively light versions of this new technology,
using a 3.5-gram receiver, have attracted fliers of small model aircraft.
Amazingly, now there is an even lighter micro version of such
equipment.
The Kyosho company is marketing a new 15-inch-span scale
model of the Cessna 210 Centurian airplane that weighs only 18
grams—roughly 2/3 ounce! It has three controls: a speed control for the
motor and two servos for rudder and elevator control.
The model comes factory finished and ready to fly. The transmitter
automatically selects a frequency the receiver indicates is clear. As
long as that transmitter frequency is on no other spread spectrum
transmitter, it will continue to select the same frequency.
This equipment operates at 2.4 GHz, so it is not sensitive to 27 or
49 MHz citizens bands, the 50-54 MHz amateur radio band, or 72-75
MHz airplane and ground-control bands.
The basic advantage is that the spread spectrum equipment can be
switched on without worry from any other on the 2.4 GHz band; it
selects a clear frequency from among the many that are available. Now
that the airborne equipment is available in micro size, a new world of
micro-flying is on the horizon.
More Micro-Flying Information: It’s not obvious in the model press
because the amount of space devoted to it is relatively small, but
micro-flying is quite big and it’s largely fed by what is much like an
underground communications system. The Internet is where most of
the information abounds.
Most who are involved either have computers or have access to one
through friends, relatives, public libraries, stores such as Kmart, and
even some restaurants that provide free computer service. MA’s Sport
Aviator Web site at www.masportaviator.com has a section titled “A
Free Guide to Indoor RC Flying.”
The guide provides a link to the online magazine called Cloud 9
RC Micro World at www.cloud9rc.com. In turn, that site provides a
link to a list of roughly 40 other RC Web sites. Click on any of the
sites listed, and a whole world of information related to micro-flying
appears, including articles, photos, plans, products, etc.
One of the most interesting of these Web sites is the Bradley
Brothers. Paul Bradley, author of the bimonthly MA column “Small-
Field Flying,” and his brother Ralph provide the site. It is full of
great information about their projects, many of which are directly
related to micro-flying. MA