Control Line Scale

Author: Bill Boss

Edition: Model Aviation - 2009/02
Page Numbers: 151,152

New custom-built electronic control system now available

Allen Cargill of Warwick, Pennsylvania, designed and builds a new CL electronic system that is available in four-, six-, and eight-channel units. Shown are the four-channel unit Allen uses and the six-channel variation that Joe Scrozczyk of Philadelphia, Pennsylvania, used for the Piper Twin Comanche I featured in the April 2008 column.

Both systems are mounted on two-line Stunt-type handles, and all the controls remain in your line of sight while flying a model. There is no need to take your eyes off the airplane or grope for controls such as those on modified RC systems that hang from your belt or strap over your shoulder.

The photos of the transmitter systems show the diverse arrangements that can be built into a unit. The four-channel setup has all channels in full proportional operational mode.

The six-channel system made for the Twin Comanche has two channels of full proportional operation and four channels dedicated to on/off switch control. The fifth switch is the on/off power switch. Proportional control might be used for throttle and flaps, and switch action could be used for landing-gear retraction, landing lights, opening and closing bomb-bay doors, and dropping bombs.

The decoder unit, shown in the photo of the six-channel unit, is small and has connector terminals for the servos and battery. There's no need for lead soldering by the user. The decoder uses the standard RC 4.8-volt battery for power. The servo connectors on the board accept Futaba and uni-type plugs.

If a servo is placed some distance away from the decoder, an extension lead with proper connectors must be made. The lead shown coming from the decoder unit is the signal lead with a two-pin connector for connection to the flying lines.

Servos and batteries are not provided with Allen's systems. However, more than one decoder unit is available for any of the three systems.

Power for the transmitter units is a standard 9-volt battery that is regulated down to 5 volts for the output signal. There is an on/off switch and a red LED on the front panel of the unit to indicate that power is activated. The four-, six-, and eight-channel units will have the 9-volt battery and its connection enclosed in the transmitter unit, rather than featuring the external battery connection shown in the photo of the four-channel unit.

Allen recommends using Futaba and Hitec servos, but he suggests that any standard RC servo (1- to 2-millisecond operation) that has the same connector wiring as Futaba or Hitec should work with no problem. The servos plug directly into the decoder.

As with all electronic systems, insulated flying lines are required. A nylon or non-electricity-conducting bellcrank and isolation of the flying lines at the control handle is also required. The photos show two handles that might be used.

Features and pricing

All controls remain in the pilot's line of sight while flying.
Four-, six-, and eight-channel units available.
Mix of proportional and switch-operated channels configurable to your needs.
Decoder accepts Futaba and uni-type servo plugs and uses a standard RC 4.8 V battery.
Transmitters use a 9 V battery regulated to 5 V for output signal.
Servos and batteries not included.

Prices:

Four-channel unit: $120
Six-channel unit: $135
Eight-channel unit: $150
Additional decoder: $20–$30 (for four- to eight-channel units)

Allen Cargill will configure systems to your individual specifications. Tell him how many proportional channels you need and how many should be switch-controlled. Allen Cargill's contact information is in the "Sources" list.

Polen Special racer

Allen Cargill scratch-built the Polen Special racer to a scale of 2 inches = 1 foot, producing a wingspan of 44 inches. The model's total weight is 44 ounces.

The Polen is powered by an AXi 2820-series motor and uses a Jeti Advance 40 ESC. Power is supplied by a Thunder Power three-cell, 3200 mAh battery. Operational features are throttle, flaps, and retracts from Robart driven by a Futaba servo. Allen uses his four-channel system to control the racer.

Dennis Polen built the unique full-scale Polen Special in the late 1960s and early 1970s. It made its first appearance at the EAA (Experimental Aircraft Association) show in 1973.

Some 20 years later, when Dennis could no longer fly the airplane, it became the property of Dick Keyt of Granbury, Texas. An American Airlines pilot and an Air Force veteran with an aerospace engineering background, Dick flew the aircraft at various air shows throughout the next several years.

Equipped with only a four-cylinder engine and with the ability to attain high speeds, the Polen Special has been called one of the most efficient aircraft of modern times. It holds a world speed record for 500 kilometers of 303.5 mph.

Dick Keyt and the Polen Special have been honored with the Blériot Medal for the aircraft's outstanding contribution to aviation. The two also participated in the Centennial of Flight ceremony that took place at Kitty Hawk, North Carolina, in December 2006.

Wanted

C. Larry McCormack of Novato, California, wrote that when he was a teenager his mother bought him a Scalemaster Ju-87 Stuka kit for one of his birthdays and that, sadly, he let it get away from him before he even started to build it. The model spanned 45 inches, was designed for a .35 engine, and was produced in the 1950s.

Larry has looked everywhere but is unable to locate one of these kits. He wonders if someone might be able to help him. If you can assist Larry, his contact information is in the "Sources" list at the end of this column.

Please send ideas, notice of upcoming CL Scale events, contest reports, and especially photos of CL Scale activity to me at the e-mail address at the top of this column or to my address listed in the Sources. MA