Author: Paul Bradley
Edition: Model Aviation - 2010/02
Page Numbers: 94,95,96
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Small-Field Flying

That looks about right ...

In the last column, I shared some of my efforts in using three-dimensional computer-aided design software for developing model airplane plans. Some of you might have heard the old expression about making the trip from theory to reality. As often happens, my path from theory—created by the 3-D design software—to reality—of a functional aircraft—had a few potholes.

The project in question was my attempt at developing a killer micro pylon racer for the 2009 Keystone Indoor Electric Fly (KIEF). Ultimately, the built-up wing did not work out well and was replaced with one of sheet balsa. It was done free-flight (FF), hand-launch-glider style.

The model eventually turned out fine, but much of my theory had to be left behind. That leads me to my point.

I received a pleasant note from Tom Keller that included a nice little all-foam aircraft he designed. I have included a picture for your reference. To design the airplane, Tom used an established technique known as TLAR: “That Looks About Right.”

This method requires no fancy design tools or involved theory. Simply put lines on paper or foam, based on your experience and sense of what looks correct. Tom was rewarded with a nice-flying model that is suitable for indoors or outdoors in calm conditions.

Build time was roughly an hour, and his airplane has an 18-inch wingspan. Power comes from an inexpensive 5-gram outrunner brushless motor driven by either a one- or two-cell Li-Poly battery pack in the capacity range of 75–140 mAh. The battery he uses depends on the flying conditions.

Controls include throttle, rudder, and elevator, and Tom uses 2.5-gram Blue Arrow servos. According to him, the ParkZone brick, like the one used on the RTF Vapor, would also work well.

The fuselage is simple box construction, made from 1 mm Depron with 1/16-inch balsa stringers, and the tail surfaces are 1 mm Depron. The wings are 1 mm Depron with thin carbon leading-edge spars, 2 mm foam ribs, 1/16-inch balsa center ribs, and a 1/64-inch plywood brace to hold the dihedral.

The wings are held on with two thin rubber bands and a thin carbon rod, which help prevent damage from unintended encounters with the ground or the wall. The model's all-up flying weight is 1.75 ounces.

Carefully applying design theory is valid and appropriate, but sometimes the TLAR method is fine for a project. Nice work, Tom. I like it.

Oh, yeah! My KIEF pylon racer got me to the final race heat. Pilot brain fade put me out of contention, but I sure did have fun.

Two Wings and Small Fields

When it comes to flying in little venues, it seems that two wings are often preferred to one. The wing area afforded by biplanes allows them to fly slowly when they are built to be light. Slow flight combined with good control response is desirable when flying space is limited. Being able to fly a nice biplane in a small-field setting is great, especially when you have a variety of designs from which to choose.

A source of such options is Pat’s Custom Models; between the models Pat Tritle sells directly and those he has designed for kit manufacturers, there are several. To make sure his biplane offerings remain fresh, Pat has added a new model to the lineup: a nice Fleet biplane. Sporting a 42-inch wingspan with a flying weight of 18 ounces, it’s a perfect small-field candidate.

Power comes from an E-flite Park 400 motor turning a 9x6 propeller, driven by a 1600 mAh, two-cell Li-Poly battery pack. That setup provides 25-minute flights. Controls include throttle, ailerons, rudder, and elevator.

As with the other biplanes Pat has designed, the Fleet’s flight characteristics are excellent. He reports that it sideslips nicely and that all control inputs are positive and well balanced. The in-flight photo Pat provided piques my interest in this design. Watch the pages of Model Airplane News for a construction article. Kits will be available directly from Pat, once the construction article is published.

I am a big fan of models with wingspans that are 24 inches or shorter. They are easy to transport, they normally require less building time, and they can be flown indoors or outdoors. The latter feature is especially nice when you are fortunate enough to have access to a facility that is inside.

John Krouse has a design intended for outdoor flying that can also be flown indoors. A feature that strikes me as interesting, and this dates me a bit, is how much the model reminds me of the old North Pacific rubber-powered Skeeter. The swept wings and general layout bring back fond memories of the many I had in my youth.

An important attribute of the Skeeter was its ability to fly well in the wind. The swept wings helped it maintain stable flight when upset by gusts. John incorporated that great characteristic into his model.

As shown, it has a 24-inch wingspan, Jedelsky airfoil, 1/16-inch balsa wing, and weighs 1.6 ounces. Power comes from a 7 mm brushed motor turning a 5x3 propeller through a GWJ 4:1 gear drive supplied by BSD Micro RC.

Controls are throttle and rudder, handled by a Plantraco Micro 9 receiver driving a magnetic actuator. According to John, his airplane can handle mild breezes well.

On the subject of models that are suitable for both indoor and outdoor flying, I have another offering from Model Aviation Hall of Fame member Bob Aberle. He has been developing 200-square-inch renditions of popular vintage designs. They are better suited to outdoor venues.

To keep things interesting, Bob has added a 75-square-inch version of the Trixter Beam to his fleet. With a wingspan of 21 inches, it is a perfect indoor/outdoor model. The nice thing about vintage designs is that their fuselage shapes make it much easier to accommodate the radio gear when done in smaller sizes.

Bob's Beam is powered with a 5-gram LCD brushless motor from BSD Micro RC that gets energy from a two-cell, 210 mAh Li-Poly battery pack. With a flying weight of 4 ounces, Bob reports that the airplane flies wonderfully. It takes off gracefully and cruises at a comfortable pace.

The plans for Bob's Trixter Beam, along with his other reduced-scale vintage aircraft, are available from the RC Micro World Online Magazine.

A 35-Year Build

How many of us have started projects and then placed them on the back burner to finish at a later time? I know I am guilty. Apparently Rodney Taylor is as well.

Way back in time when the Ugly Stick was new, Rodney flew a glow-powered, two-thirds-size version of the ubiquitous design. Since he liked that size a great deal, he decided to build a 1/2A Ugly Stick when he stumbled upon plans by Bob May. The design used the then-popular Ace foam wing panels.

Rodney started the model but did not finish it at that time. It went through a house move and many years of dusty storage, and he rediscovered the project roughly 35 years later.

In the beginning, the airplane was going to get a nice two-speed Holland Hornet .051 glow engine for power. Rodney has since gone to electric power for his smaller models, so for the Ugly Stick he selected a 60-watt brushless outrunner motor that turns a 7x6 propeller, powered by a 600 mAh, three-cell Li-Poly battery pack. Control functions are handled with a modern digital spread-spectrum radio.

Rodney reports that the model flies like a Stick and gives him 30-minute flights. I have included a picture of Rodney holding the model. It was taken at the 2009 annual DEAF (Dallas Electric Aircraft Fliers) Fly-In.

Way to go, Rodney. You not only finished that 1/2A Ugly Stick, but you should be able to enjoy it for years to come.

Glen Allison, Rodney's close friend, seems to share his long-term project cycle. Near the time Rodney was completing his 1/2A Stick, he received word from Glen that he had also completed a project that he first considered in the early 1950s.

In 1952, Glen saw a three-part article covering the full-scale Mechanix Illustrated Baby Ace that Paul Poberezny designed. Glen did not start his model version of the airplane then, but he had the idea.

Roll the clock forward to the present, and Glen was able to acquire a copy of the Baby Ace article from the EAA's AirVenture Museum. Based on the article drawings, he developed plans. The resulting model turned out to have a 34-inch wingspan—just right for small-field flying.

Glen's Baby Ace is powered with an AXI 2703/52 brushless motor swinging an 8x3.8 propeller. The battery is a two-cell, 730 mAh Li-Poly pack. Flight controls include throttle, ailerons, rudder, and elevator.

Glen reports that his design has good flying qualities and a flight duration of 30 minutes. It and Rodney's 1/2A Ugly Stick turned out wonderful.

This brings us to the close of this column edition. Let me know what you are up to, so I can share your work with the rest of the small-field-flying community.

MA

Sources:

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