Newcomers
Bob Underwood
<REDACTED>
LET'S TAKE care of a few housekeeping items before we get this column underway.
For seven years I've maintained a post-office box where AMA mail was to accumulate. The metal container at Box 40, St. Peters MO often did what it was supposed to: collect my mail.
But not always!
In spite of pleading with, threatening, and cajoling every employee in the St. Peters post office, I kept getting other people's mail; Box 100 was the winner by far. It makes me wonder how many pieces of mail for Box 40 found their way into letter limbo.
So, I've dropped the post-office box. If you want to write to me, send it to AMA Headquarters (5161 E. Memorial Dr., Muncie IN 47302); they'll get it to me. If you're electronically inclined, send an E-mail to <REDACTED>.
I travel quite a bit for AMA, and may not be sitting with my finger poised over the keyboard to type a return E-mail, so pass along a telephone number and I'll give you a call.
I need to clear up a sentence near the end of my April 2001 column. If you read it, you may have thought: 1) He's lost his mind! 2) What an insult to clubs! 3) What does he mean? 4) All of the above!
Following a list of tongue-in-cheek "laws" I penned about clubs, I concluded with the statement, "All so-called 'club laws' are inaccurate, and cannot be relied upon as factual."
I was trying to say that all of the laws I had mentioned, written by me, could not be relied upon as being factual — not that your club laws are inaccurate.
The funny thing was that I was at the WRAA (Westchester Radio Aero Modelers) trade show in New York when I first saw the April 2001 Model Aviation. There's a three-month lead time for columns, so when an issue appears I turn to my column to see what I wrote about!
I looked at that sentence, and immediately searched through my aging brain to try to figure out how I could have written such a thing.
My "administrative assistant" (wife!) asked me at the time she typed the column if I really wanted to include that closing. In a typical husbandly manner I replied, "Of course! I know what it says." Three months later, I didn't.
Sorry, clubs!
What powers a model aircraft?
In one way or another, all model aircraft are powered. Before you challenge that statement by writing that your sailplane or glider isn't powered, take a few minutes to think about the statement and laws of physics.
Something causes it to move forward, create lift, and fly! Maybe you throw it, tow it, drop it, or kick it, but it moves. Otherwise, it just sits on the ground or your fireplace mantle and it's not an airplane.
Forget for a while about your arm flinging it and tossing it off a mountain, and about rubber-band power, and concentrate on internal-combustion engines and electric motors turning a propeller to make it go. Forget about pulse jets and turbines as well. A newcomers' column shouldn't suggest either of those as a starting point.
There's a set of linguistic problems and definitions that can trip you up when you speak of "engines" and "motors" as power sources. You often see the two used interchangeably; Mr. Webster does that in his big book!
Both are devices for converting various sources of energy into mechanical force and motion. Webster's Collegiate Dictionary mentions electric and gasoline when referring to motors.
Most people tend to refer to "gasoline engines" and "electric motors" when trying to differentiate them. To further complicate the matter, modelers will often refer to the internal-combustion part of our sources of power as "gas-engine" powered.
The bulk of models — especially those flown by newcomers — are not powered by gas engines (as in gasoline). They use alcohol, nitromethane (sometimes), and lubricant as fuel. Some of the larger engines do use gasoline, but they are not generally found in trainers.
To complicate the issue even more, you can find diesel engines for models and little devices that use CO2 gas for power!
Now that you are completely confused, let's look at the ordinary glow fuel–powered engine.
There is a wide variety of sizes. The airplane you choose will dictate a certain range. Years ago the tendency was to stick to the lower end of the manufacturer's recommended range; the opposite is true now.
The age-old admonition that you can always throttle back, but you can't find extra power seems to have caught on.
You do need to be careful not to produce a lean, mean racing machine. That's not what you want for a trainer! And remember that more power means more fuel, more weight, etc.
There is a movement by manufacturers in recent years that involves taking a basic engine design and increasing the displacement without increasing the physical size. They do this by changing the bore and/or stroke of the engine. The result is an engine that fits the same physical space, but produces greater power.
A benefit can be that the engine actually loses weight! As you look ahead, this may be something to think about.
Within any given engine size, there is a wide range of prices. Although some of this disparity may be the result of production methods and the general economy, the bulk of the difference is likely to be the quality of the product.
A very basic two-stroke engine will not usually contain the construction niceties in the higher-priced product, such as ball bearing–supported crankshafts as opposed to bushings.
If you feel that the primary task of any engine is to help you learn to fly, maybe the reduced cost of the more basic engine is a logical choice; after all, there isn't much need to achieve top performance levels at this point.
More engines are featuring remote or rear-mounted needle valves; this is a very important consideration. One of the greatest threats to modeling safety comes from engine adjustment through a needle valve mounted less than an inch behind a propeller. The mere act of grasping a needle valve tends to place a bent knuckle in harm's way!
You may want to consider the method of how you will mount and adjust the engine as you make your selection.
Construction of the engine varies. Some modelers use a crankcase produced in one piece, with a single rear coverplate bolted on. Others use two covers — front and rear — bolted to the primary crankcase. There are advantages and disadvantages to both.
However, more often than not, these areas relate to performance — not generally critical for the newcomer.
Advertisements will often focus on the materials used in the engine. The most often-described feature concerns the combination of metals used for the piston and the cylinder sleeve. Typically, the more the ad touts these features, the more they will relate to the performance and cost.
The combinations of metals and plating and the fit of these parts can have an important effect on how the engine is treated — especially during any recommended break-in period. That's why that often-neglected (or totally disregarded) item called "directions" is very important.
For instance, the difference between the metals and fit of a ringed-piston engine and one that does not have a ring is the break-in technique suggested. They also have a different feel when the propeller is flipped through.
Four-stroke vs. two-stroke
Ever-increasing numbers of four-stroke engines are used at local flying sites. A decade or two ago, they were not often considered because they did not produce as much power for their weight and size as the two-stroke. That has changed significantly in recent years.
Four-stroke engines do tend to produce more torque at lower revolutions, and they swing bigger propellers.
However, there are two major negative features: they are more expensive and they have more moving parts. The pushrods, valves, etc. necessarily create these scenarios.
The four-strokes are physically taller in size, and generally weigh more for any given displacement.
Because of the lower operating rpm range and the ability to use larger propellers, four-strokes tend to create less sound. And the frequency of the sound is less objectionable.
Overall, the four-stroke seems to be more pleasurable when compared to the two-stroke.
Depending on the company you are in, you often hear the terms "two-cycle" and "four-cycle" used interchangeably with "two-stroke" and "four-stroke." Which is technically correct? For this column, all you really need to know is that two types exist so you can consider them in the context mentioned earlier.
Electric power
What about an electric motor? I probably wouldn't even have mentioned it for a newcomer a decade or two ago, but now it needs to be considered.
The progress made in power plants and batteries has been unreal. The power output of both has achieved levels rivaling glow engines in many ways. It seems impossible to keep up with technology.
Early electric-powered models were typically heavy, underpowered, expensive, they produced short flying times, and they required special modeling skills. The manufacturers have responded to the challenges, and now it is a most viable power source.
Electric fliers love to point out that there's no need to clean messy models or "fuel-proof" finishes, and a number of other virtues. Flying times — especially at the lower power settings — provide an acceptable amount for training purposes. And, yes, they are quiet — very quiet!
One of the most helpful parts of electric flight improvements has been charging and battery-management systems. The ability to successfully quick-charge at the field and monitor the condition of the system is very helpful.
Are there any downsides?
Possibly. Electrics do require some techniques and cautions not necessarily present with glow engines. Because of our experiences with electric motors outside of models, we are sometimes not aware of the need for cooling the motor and batteries. The latter also involves a heat problem in the charging mode.
There is an abundance of good information available to help in this respect. The terminology and techniques (such as soldering) may also require some education. Propeller sizes relating to performance and model weight also compute a bit different from glow engines. But none of this is a problem if you check sources carefully.
When working with the average local AMA club, one problem for the newcomer may be locating knowledgeable sources within the group. There are ever-increasing choices for trainers in the electric field. There are models designed specifically for electric power, and they combine a correct power source for weight and size. These models range from micro for indoor flight, to park flyers, to larger powered sailplanes, to models closer in appearance and size to glow-engine types.
If you want to adapt a normal glow engine–powered model to electric power, you will need some consideration regarding power and battery requirements. One aspect you can keep in mind is that certain parts of the model structure can be reduced in weight.
There are many approaches to powering a trainer. The type used is probably not as important as the quality of help you receive and the concentration you associate with the effort involved in learning. One of these you can encounter; the other is more difficult.
That's why it's so important for you to do research to see what's available before taking the plunge.
Happy flying!
Transcribed from original scans by AI. Minor OCR errors may remain.
