Author: Paul Bradley
Edition: Model Aviation - 2009/08
Page Numbers: 91,93,94
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Small-Field Flying - 2009/08

Paul Bradley | [email protected]

The addiction of trying a new aircraft category

In the June column, I had the opportunity to share with you a departure project from Pat Tritle. Normally known for his excellent small-field scale models, he ventured into the world of converting vintage rubber-powered airplanes to RC.

The model was a nice RC electric-powered Midwest Jabberwock. The fact that Pat is a longtime free-flight (FF) builder as well as a prolific RC scale designer means he placed his foot on the proverbial slippery slope. After experiencing the joys of flying his Jabberwock, Pat decided that he needed another vintage rubber-powered airplane conversion.

This time he applied his design skills and developed a 55-inch-span version of the venerable Comet Sparky that Ed Lidgard designed. It is one of those designs that anyone who has been in the hobby for a while and has enjoyed the world of FF at one time or another might feel the need to build. The Sparky has lovely lines. Pat’s version is approximately double the size of the original and retains all of the eye appeal.

The converted aircraft is powered by a Suppo 2208-13 outrunner motor that turns a GWS 9 x 5 propeller using a two-cell, 1600 mAh Li-Poly pack. Controls include rudder, elevator, and throttle. At a flying weight of 14.2 ounces, the Tritle Sparky is a relaxed flyer—perfect for small-field venues.

Pat is offering Sparky kits now. They include all of the laser-cut parts, full-size plans, and a custom-made spinner that gives the model part of its special look. See the source information at the end of the column for contact information.

Although Pat Tritle has shown us his vintage rubber-powered FF conversion, he is still producing new scale designs aimed at the small-field-flying devotee. His recent designs have been at the larger end of the spectrum. Recognizing that transporting bigger models to the flying field and other factors can be issues for some of us, his latest offering is what I consider the “sweet spot size” for small fields: airplanes with wingspans of approximately 40 inches.

Look at the photo of Pat’s new 40-inch-span J-3 Cub. He has developed Cubs in other sizes and, at first blush, his latest version might look like a simple rescaled version of an existing design. I have spent numerous hours developing a design and can tell you that changing a model’s size involves much more work than simply telling the computer to change a drawing size by a given percentage value.

By the time you accommodate changed wood sizes, structural changes to reflect the new size, power installation, and related factors, you have a new creation. Pat’s medium-size Cub is the same way; it’s a new design. It is extremely nice and a great fit for those of us who fly in venues that are at the smaller end of the field-size range.

The Cub has a flying weight of 7.2 ounces. With a wing area of 230 square inches, the loading is only 4.5 ounces per square foot. Power turns an 8 x 6 propeller. Energy is provided by a two-cell, 430 mAh Li-Poly pack. Rudder, elevator, and throttle controls are employed, and the model gets 20-minute flights. The plug-in wings make transporting the Cub easy. Pat reports that the airplane’s flying qualities are excellent: the controls are responsive but not twitchy. It’s great for flying sites where you have to maneuver in a fairly tight box.

If you want one of these 40-inch Cubs, Pat has kits available. They include the full-size plans, all laser-cut parts, and great Keith Sparks-produced vacuum-formed cowl/engine cylinders. Pat’s contact information is at the end of the column.

Our hobby is constantly changing. It seems that there is something new almost every month—especially in the world of micro RC. What was once reserved for the dedicated specialist has become available to anyone with an interest. This means that anyone with a desire to experience diminutive models can venture into this fascinating world.

However, the wide range of options makes it daunting for someone who is just getting started. Heck, it can be daunting for those of us who have been involved in micro-flying for a while. Fortunately, Bob Aberle has released a great reference on the subject.

The World of Indoor/Micro Radio Controlled Model Aircraft is a CD laid out in traditional book format. There are several benefits to having such a reference in this format: it keeps the cost down, and the content is searchable. You can plug in a subject of interest, and the computer will find all the instances in the book. That beats flipping through the pages of a traditional paper book.

You will find 138 excellent photos and comprehensive coverage of the world of micro RC in Bob's 118-page book on CD. At $13, which includes shipping, you can't go wrong. To get your copy, visit John Worth's Cloud 9 RC Micro World website.

RTF and Innovation

Not long ago, I shared some thoughts about members of our small-field-flying community using equipment supplied with ParkZone micro RTFs in their models. The ParkZone brick micro-receiver package is terrific, but it's not the only resource for the innovative micro-airplane builder.

I received correspondence from Ron Bartley of Canada regarding his employing the gear from a Megatech C.C. Flyer. He was not completely happy with the way that model performed, so he built his own airframe. This was Ron's first venture into the world of smaller RC aircraft.

The Megatech system is somewhat limited in functions compared to the ParkZone brick radio package. It offers only throttle and nonproportional rudder control. Given the C.C. Flyer's limited capabilities, Ron selected a design from the era in which bang-bang rudder-only control was the norm. He chose the wonderful Bob Coon-designed Guided Mite that appeared in the April 1958 Flying Models. With a wingspan of 21 inches, the Guided Mite was perfect for the Megatech gear.

In addition to the radio, Ron also used the motor and a five-cell, 180 mAh NiMH battery pack. The model's final weight was 4.5 ounces, and it gives nice five-minute flights. Ron is justifiably happy with his first venture into the world of "micro" RC—especially since he could use the gear from his C.C. Flyer. Ron sent photos so you can fully appreciate his excellent work. If you have Internet access and would like a copy of the original Guided Mite construction article, visit the Web address listed in the Sources section.

An Old Problem With a Nice Solution

One of the major benefits of writing this column is the wonderful correspondence I receive from readers. The pen pals—perhaps that should be e-mail pals—I have been able to enjoy are a bonus.

One such friend is Sam Will of Arizona. We were recently comparing notes regarding our respective builds of Pat Tritle’s 44-inch Tiger Moth, and Sam mentioned a neat way for retaining the wheels.

Since the Tiger Moth is a scale model, Sam wanted to keep with that spirit in doing the wheel retention, but not necessarily a scale representation of the full-scale airplane. The system he came up with involves slipping a piece of brass tubing over the bent piano-wire axle. A brass bushing is held in place with thin CA.

The brass tubing extends out just past the width of the chosen wheel. A small hole is drilled in the end of the tubing. The wheel is placed on the brass-bushed axle, and a homemade cotter pin is inserted. The cotter pin gives the wheel retainer a scale feel and is easy to remove in case Sam wants to service the wheel.

I often have to bush the axle for the wheels I select, and this straightforward retention system is perfect when a bushed axle is being used. Thanks for the great idea, Sam.

This brings us to the conclusion of this installment. I love hearing from you, so don’t be bashful about sending an e-mail or a letter via postal mail. My contact information is in the source listing.

Sources

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