John Worth offers a heartfelt farewell to Dave Robelen
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.)
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
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-inch wingspan, 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 balsa-frame, 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 23 mm — 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 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 one-cell 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 x 12 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 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 Centurion 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 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 surface-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.sportaviator.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
Transcribed from original scans by AI. Minor OCR errors may remain.
