Safety Comes First
Gary A. Shaw
5063 Benton Boulevard, Pace, FL 32561
For many years I've looked forward to a little quiet time at the end of a day and the opportunity to spend a few moments flipping through the pages of a model magazine (in peace) to see what new gizmos were for sale, to laugh a little with "The Microhenrys," or just to read up on emerging technologies. It seems like no matter where you look in this hobby there's so much happening that being able to absorb it all—at least for me—seems to be virtually impossible.
I find the diversity of the hobby to be fascinating. Even though I've been involved for a number of years, there always seems to be something new on the horizon that spikes my interest, then suddenly I go off again spending countless hours trying to master the new attraction or at least learn to do it safely. There's nothing better than letting your imagination break away from the real world once in a while to fly a model, a paper airplane, a kite, or "whatever."
Looking back at the year gone by, I hope you took plenty of time to break away with family and friends and let yourself enjoy what the hobby is really all about—having fun and relaxing! If you didn't—shame, shame, shame on you!
In retrospect, 1996 sure was an action-packed year for the hobby, and one that reflected continued concern for improved safety. Looking through the numerous publications, columns, and ads, safety continued to be one of the common themes, and rightfully so! I hope the trend continues and we are all able to learn something from what has been written. The bottom line is to do it with care or don't do it at all!
Rejuvenate Your Old Fuel
If you haven't learned to use the power of the Internet, you're truly missing one of the most powerful electronic resources ever known. There's so much information available at your fingertips that finding facts on just about anything is as easy as clicking a mouse.
While scanning the Net for RC-related topics, I saw an article written by Tim Skloss. Tim works for Texas A&M's Department of Chemistry, in the Laboratory for Magnetic Resonance and Molecular Science—and he's also a modeler! Tim posted a piece for modelers that describes how to remove the water that accumulates in fuel—even after it's been sitting around for years.
Why should we care? Well, for starters, fuel certainly isn't cheap, which makes it difficult for most of us to dispose of when we suspect it has become unreliable because of water contamination.
I've seen more than a few aircraft return to the ground in a hurry because of fuel that wouldn't combust properly. Some were very spectacular; others merely hiccuped as they traveled down the runway. Bad fuel can—and has—led to accidents that could have been prevented if Tim's fuel-rejuvenation method had been applied. Here's a review of Tim's information:
"If you have a problem with water in your fuel, there is a simple way to reduce it to below the part-per-thousands level. In my lab, I use molecular sieves—porous crystals that let molecules of certain sizes inside. Once inside, the polar nature of the crystal's structure binds to other polar molecules (e.g., water) and won't let them out without lots of heat. The crystals hold approximately 20% of their own volume of water and can be rejuvenated (made reusable) by heating them in an oven for a few hours above 300°F (or above 120°C, but not more than 370°C/700°F). While they're still hot, transfer the rejuvenated crystals to a glass bottle (a wide-mouth pickle jar is good) and cap it tightly after a minute. This ensures that the crystals will stay water-free until the next use."
Source: I get my crystals from our stockroom; they are pretty cheap. The reagent-grade sieves that I use are about $7 for 1½ pints of 1/8-inch-diameter beads. Normal-quality sieves are also available and should cost less.
Important: Molecular sieves are also called zeolites and are available with different pore sizes. The one we want is size 3A; 3A stands for 3 angstroms. This size lets water in, but not methanol or anything else larger (nitromethane or oil). Size 4A will adsorb methanol, and that's bad for us.
Also important: The sieves may make dust when they rub together, so a final filtering into a clean container is best before heading out to the field. The fuel should be clear—not cloudy. If it's not clear, you may have accelerated engine wear.
This will help those who demand high performance from their fuel for their high-performance engines—helicopters, ducted fans, competition. So why go out with questionable fuel?
Note that 3A molecular sieves are used in the industrial drying of nitromethane, and have been used extensively in the chemical industry since 1957. There's an awful lot of it around; you just have to know where to look. Molecular sieves are non-toxic, but don't put them in your mouth—they give off a lot of heat when they adsorb water. Basically, they are a form of glass and sand.
Some things to note about Tim's article:
- A source for the crystals was not mentioned; I'll have to find one and include it here at a later date.
- If the crystals he mentioned work anything like the ones I've used in photography, they'll turn blue when they're saturated with water, so you'll know when it's time to rejuvenate them.
- The crystals can produce dust if they're rubbed together; fuel filtration is recommended to prevent premature engine wear.
I'm wondering if the heat generated as the crystals adsorb water from the fuel is enough to cause combustion. If any of you have knowledge to share, please drop me a note so I can pass it on at a future date.
Winter Ski Fun
I thought you might enjoy some information provided by "Bill" (that's all I know) on how to construct RC snow skis and fly with them. You can have a lot of fun with winter flying, provided a certain degree of caution is used. Remember, equipment seems to get more brittle when it's used in the cold, and more props get nicked or broken more routinely. Here's Bill's information:
"Flying in the winter off snow or ice can be really fun. The engine puts out more power and the airplane flies slower, so you have a nice combination. If you want to try it, get some lighter fluid to help start the engine (put a little in the carburetor just before spinning the prop). Keep the fuel from getting too cold, and keep the batteries warm until just before you are ready to go. You might want to go to a smaller prop/smaller pitch, since the prop will turn slower with cold temperatures. On my sailplane, I flew quite well with a 5 x 3 prop during the winter, but during the summer I couldn't keep the airplane flying level with a 5 x 3 prop, and I used a 6 x 4 prop for best performance.
When you install skis, make sure they'll never flop forward. Even backward is quite bad, since they will act like ailerons and could easily crash the airplane. A couple of rubber bands over the fuselage attached to the fronts and backs of the skis is one way to do this. This also lets you track with the ground fairly well.
Making the skis is fairly easy. Cut a piece of 1/8-inch plywood about three inches wide and 6–12 inches long. The size depends on the airplane; a 3 x 6-inch ski is the right size for a .40-size airplane. The front of the ski must be curved; a semicircle will do, but something slightly more pointed is better.
Cut a 1/2 x 3/4-inch piece of pine to run down the top center of the ski. Drill the front end holes to curve up in the last inch so that the front of the ski is raised. Drill a hole just in front of the ski's center of gravity, so the ski will flop backward if anything happens.
Mount the skis in place of the wheels. Use elastics (or something) so that the skis will stay level in flight. There are several designs that will work; figure one out if you don't like the elastics idea.
Paint the skis. If you want, you can wax them. If you want to cover the skis, one of the fabric covering materials is your only choice.
Deep-powder snow and very wet snow are your enemies during takeoff. For deep powder you'll need to use water floats. Very wet snow requires either waxing the skis (with ski wax appropriate for the temperature) and/or spraying them with Pam (you know, the kitchen stuff). If the snow is over a patch of grass, you sometimes use Pam to enable you to get up to takeoff speed.
Some things that are fun with snow are:
- Shortest takeoff. It is often possible to take off in one meter.
- Bounced takeoff. Make a pile of snow, run the airplane toward it, and bounce into the air.
- Dropped takeoff. Use the pile of snow, make a sudden drop, and run the airplane off the edge of the snow. This works well if you have picnic tables at the flying field; they're just the right height.
- Fastest non-takeoff time over the bump. Steer over some bump in the snow without taking off; this is difficult when the snow is fast.
- Just playing around without taking off!"
Transcribed from original scans by AI. Minor OCR errors may remain.
