Edition: Model Aviation - 2010/11
Page Numbers: 85,86,89
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Frequently Asked Questions

Bob Aberle | [email protected]

Q469: Invisible control system

Q: "I have heard for many years references to so called 'invisible control systems' for model aircraft where the control linkage is all internal to the structure. Recently I read on one of the nets that someone was in the process of producing and marketing an invisible control surface system. Do you know if this actually happened?"

A: Yes. Harley Michaelis, noted RC sailplane designer and author, has submitted to MA a "how-to" article titled "The Invisible Control System and What It Can Do for You."

Many aeromodelers have fashioned such control systems over the years, but it was typically done on an individual basis. Harley developed a special setup called a Rotary Driver System (RDS). This product is being mass-produced by Kimbrough Products and is distributed by Walt Dimick, a modeler/machinist who does business as I.R.F. Machine Works (see Sources).

The RDS consists of mechanical components that connect to the output shaft of any standard RC servo. The rotary motion of the coupled output arm is translated into a rocking action that raises or lowers an aileron or flap-type control surface. The entire RDS is installed inside the wing, so no control rods, horns, or clevises are visible from the outside. That yields zero external drag and a clean appearance in flight. While Harley uses the system on sailplanes, it also applies to scale models and pylon racers where appearance and drag are important.

The article and the RDS web pages include photos and diagrams showing how the system works and how to install it. I urge you to review them and study the installation details carefully.

Q470: Single-channel RC and diesel power (converting a free-flight Sioux)

Q: "I noted in a recent magazine column a photo of Joe Wagner's Sioux, a free-flight design from the fifties that had been converted to single channel RC and was powered by a tiny diesel engine. I'd like to try something like this. Can you start me in the right direction?"

A: This topic is close to my heart—my first model in 1950 was Joe Wagner's Dakota biplane. Joe designed several free-flight aircraft around that time, including the Sioux, Navajo, and Comanche. I believe he still sells plans (he writes "The Engine Shop" column for MA). See Sources for contact information.

The Sioux you referred to was likely controlled by a single-channel ACE RC pulse-proportional radio using an Adams magnetic actuator for rudder-only control—that's how many of us flew in the 1950s. Rudder-only RC is enjoying renewed interest; groups like the Vintage R/C Society do this style of flying. You may find ACE RC single-channel systems on eBay or model forums.

A modern alternative is a micro 2.4 GHz receiver (for example, the Spektrum AR6110) with a single microservo and a suitable Li-Po battery pack to create a compact single-channel system.

With single-channel control you typically have no throttle control of the motor, so you fly until the engine runs out of fuel and then glide to land. This is where small diesel engines are useful: many older diesels started easily, ran well, and often had no throttle, which suits single-channel operation. Diesels run by compression ignition—no glow or spark plug is required. You prime/fuel the engine, flip the prop, and adjust the compression until it starts.

In the early 1990s I bought several small AE Diesels from Dave Larkin; one I have is 0.1 cc (0.006 cu. in.), which is tiny. If you want to use such a small engine you might scale the Sioux down. I also own a new McCoy .049 diesel (found via the Model Engine Collectors Association swap sheet), which would suit the original-size Sioux.

Additional resources and vendors:

  • Bob Davis of Davis Diesel Development sells diesel conversion heads for many glow engines.
  • Eric Clutton ("Dr. Diesel") sells diesel engines and diesel fuel (a specialty item).
  • Ronald Valentine Engines makes custom and replica diesels (quality, but costly).

If you try single-channel RC with diesel power, please write in and share your experiences.

Q471: Williams Brothers pilot heads

Q: "Years ago a company called Williams Brothers Model Products sold a line of plastic scale-like pilot heads or busts. They came in many types and sizes. Is that company still in business and do they still offer these pilot figures?"

A: To check whether a company exists or sells certain products, try a search engine. I used Google for scale pilot heads and found RC Hobbies and More (see Sources). I was finishing a 1/12-scale replica and needed a pilot head; they were selling a Williams Brothers pilot figure (item 18200) for $2.65 plus shipping.

When the head arrived I found it was new stock, so Williams Brothers Model Products must still be in business. Williams Brothers is now a division of Brett Industries; their site lists the old Williams Brothers accessories, including vintage wheels, scale engine parts, and dummy radial engines.

I rushed the painting of my pilot head—painting should be done with plastic-friendly paints and fine brushes. MA Editor Emeritus Bob Hunt produced a video titled How to Paint Pilot Figures (narrated by Don Typond). Bob sells the video on DVD for $19.95 plus $4.95 S&H (see Sources).

Q472: ParkZone Vapor landing gear failures

Q: "I have a ParkZone Vapor RTF indoor RC model aircraft. This plane is a delight to fly, even in small gymnasium-type facilities. The only problem I've had involves the landing gear. Mine has broken several times. In each instance I was able to purchase a replacement gear, but this problem continues and is annoying. Have you heard of other modelers with this same difficulty and if they found any solutions?"

A: I had heard about the Vapor landing gear issue. Gordon Johnson, a noted indoor RC expert, devised a laser-cut plywood landing gear bracket replacement specifically for the Vapor. It can be adapted to similar-size profile-fuselage models. The parts come on a small sheet of plywood. Bob Selman at BSD Micro RC sells this bracket—see Sources for contact information.

Q473: Programming cards and motor direction for ESCs

Q: "You recently talked about programmable ESCs and how you can set some of the electric motor parameters to suit your particular motor and battery pack. You liked in particular the Castle Creations Castle Link interface and software because it included Motor Direction (forward or reverse) function. To use this link it must be hooked up to a PC. Do any of the programming cards (that operate without the need for a PC) offer the motor direction capability?"

A: Yes. Castle Creations has released an inexpensive Field Link programming card that provides motor direction as a function, along with many other programming choices.

Sources

Transcribed from original scans by AI. Minor OCR errors may remain.