Author: Bob Angel
Edition: Model Aviation - 2011/06
Page Numbers: 126,127,128
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Old-Timers

Bob Angell | [email protected]

A Southwest Regionals report

I attended this year’s Southwest Regionals, which is held in Eloy, Arizona, each January. The FF and RC sides of the expansive field are thoughtfully separated by almost a half mile for safety. The FF venue sees higher attendance because it incorporates several modern events along with Society of Antique Modelers (SAM) Old-Timers (OT). The RC site is strictly SAM OT RC.

I was busy flying and timing OT RC, so I spanned the gap only once, to observe the FF action and attend the open-air swap meet. The swap meet is similar to a flea market, with no charges to the seller or buyer. The sellers provide their own setup and tables.

The swap meet is a good place to pick up hard-to-find kits, plans, engines, and other OT supplies. I came back with another engine that I couldn’t do without.

A highlight on the RC side is the Saturday-evening outdoor social hour, featuring a campfire, barbecue cookout, and self-provided musical entertainment. Dick Griswold, the late SAM western-region vice president, hosted the gathering for years. This year his widow, Ann Maly, generously stepped in to fill the void, with lots of help from friends. We enjoyed ideal weather and some great desert sunsets. Caley Ann Hand took many pictures, including one of Dick Nelson’s Powerhouse. But she’s also an enthusiastic modeler, who entered F1G—one of the FAI events. She was one of five in a field of 12 competitors who completed five max flights to put herself in the flyoff. Caley said that she surprised herself as well as the others by winning the event. Al Lidberg, who has managed the Southwest Regionals for several years, has a great website with complete results of all classes and a large album of excellent photographs. There are reports not only of this year’s events, but also of each contest from the last 10 years. The address is in the “Sources” listing.

Scaling published model designs to different sizes was done often in the early days. The main reason was that engines were relatively expensive and prized possessions. Few aeromodelers owned them, and those who did usually had just one. In some cases a model club jointly owned an engine that was swapped in and out of various models that individuals built. So published plans were often enlarged or reduced to fit the power plant on hand. If you double the wingspan of an airplane, the wing area increases by squares to four times the original. Wing area is the more important dimension to consider when scaling; as it increases, the required horsepower goes up even faster. But that’s another subject.

We use a simple formula to arrive at the wingspan and other dimensions needed to change to the wing area selected. The formula produces what’s called the “scale factor.” This can be used as a multiplier to arrive at the new span, along with any other dimensions of the new-size model. You start with the wing area (in square inches) of the plans to be scaled and with the new wing area you’ve chosen. To get the scale factor, you divide the square root of the desired area by the square root of the area of the original plans. If you’re scaling the original size larger, the scale factor will be a number greater than one. If you’re shrinking the size, the number will be a decimal smaller than one.

In either case, you can multiply the wingspan and every other dimension to arrive at the new size. But few of us are into drafting, so you can take the original plans to a good copy shop to get them shrunk or enlarged to the desired wingspan.

Escapements were used for flight control in the early days of RC, before servos came into use. Raymond Tinley of Mt. Prospect, Illinois, sent me a package and a brief description of escapements, including a CD with four photos of an escapement demonstrator he built. Since this column has a three-photo limit, I’ll forgo the pictures and give you a brief description.

Model escapements operate similar to those in mechanical clocks, watches, and other timepieces. But a wound-up rubber band, rather than a heavier spring, is normally used for power.

A radio pulse activates a relay (electromagnet), which trips a rotary mechanism to advance one notch for each pulse. Every notch moves a control in a different direction. The whole thing operates in a loop, finally cycling back to neutral.

Simple escapements operated only the rudder—full right, full left, and back to neutral. But later, more sophisticated versions operated multiple controls. Raymond describes his mock-up demonstrator as follows:

"Probably most of the R/C'ers today have never heard of or seen an escapement, so I thought it would be interesting to show how they worked. The planes we used them on would pretty much fly themselves, so all we were doing was to get them back without running after them.

"I use an old single-channel Min-X transmitter and receiver on 27 MHz to operate the escapement. One pulse and hold on the transmitter releases the rubber-band-wound escapement and it stops at the first position which moves the rudder to the right. A second pulse and hold moves the rudder to the left and a third pulse and hold kicks the elevator up. No down elevator. With no pulse from the transmitter, everything goes back to neutral."

Thanks, Raymond.

Those early transmitters had only a single push button for control—no sticks. Timing of the pulses and holds was the key to it all. As escapements became more developed and complex, pilots were able to do amazing aerobatics with just that push button.

Bill Schmidt is a prolific builder and innovator. He forwarded me a shortcut method that he often uses to make wooden wheels for small models.

He visits the section of home-building supply stores where various wooden drawer pull knobs are displayed. By choosing rounded knobs of the appropriate diameter, he has only one side to shape.

Bill carefully saws off the unneeded portions on the backside of each knob. The screw holes are already centered, so it’s necessary only to drill and fit small screws or dowels to allow rounding and finishing the second sides in a drill press or lathe.

The final step is to fit the center hole to the proper axle size. A glued-in dowel can be drilled out to size, or in some cases a small piece of tubing may be installed.

"RC assist" has become an obsolete term in the SAM rule book. Anyone who has watched a hot RC competition model climb out, shut down on command, and bunt over into a glide can't deny that the models are under full RC control.

The rule book was purged of the word "assist" some time ago, although the word somehow snuck back into the RC nostalgia event. But the term could be introduced again, because a few FF fliers have found a sane and practical use for a simple engine cutoff.

When a powerful FF model takes to the air and is obviously looping out of control, the situation rarely results in a happy ending—let alone a max flight. With the widespread use of 2.4 GHz radios, it's now possible to initiate engine cutoff under these conditions, often saving the flier grief while not interfering with regular RC operations.

If this simple safety measure becomes common for FF, there will be little or no effect on competition as long as rules void the flight whenever RC cutoff needs to be activated. There would be little effect even if the flight wasn't voided. A few purist FFers might be horrified by the thought, but the practice is sensible enough to prevail in some form in the long run.

A similar step has already been taken toward improving safety for SAM FF. A rule was voted in last year to allow (not require) the use of 2.4 GHz (only) radios to activate DTs. According to one knowledgeable FF CD, this was done solely to "reduce excessive chases and reduce fire danger."

That rule allows an FF model to complete its flight uncontrolled as long as it's not too windy and the airplane is staying reasonably close to the field. But if wind and thermals threaten to take it into the next county, it can be safely brought down early.

Since it wouldn't be prudent to DT with the engine running, it would make sense to allow early engine shutdown as part of the process. This would be needed only if a model were out of control. Otherwise the engine would have quit through onboard timer action well before DT action might have been needed.

The 41st annual United States Free Flight Championships is scheduled for September 23–25 at Lost Hills, California. The "Sources" section includes websites you can visit to learn about the airfield and the contest.

The multitude of events each day is separated into Modern, Nostalgia, Classic, and Old Timer. Depending on your age and outlook on life, the Nostalgia and Classic events might be considered Old Timer as well.

Ted Firster will be the CD for this event. See "Sources" for his contact information.

Flying Aces Club President Ross Mayo has sent out updated contacts for the organization. See "Sources" for the website address; go there for current information.

MA

Sources

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