AIR WAVES

Model Airplane News, Feb 2004

HAPPY 75TH

I read that Model Airplane News is celebrating its 75th birthday, and I just want to tell you how great your January 2004 issue is. Reading about many of the old articles brought back fond memories of when I started flying model airplanes with my father in Van Cortland Park in New York City. Back then (the early '60s), we flew a collection of old free-flight models and longed one day to control a plane by radio. I want to thank Nick Ziroli, Dave Gierke and Bob Aberle for their nostalgic editorial. Thanks for the memories.

Bob Oldenburg

New York, NY

Bob, thanks for your words of encouragement. We had a great time working with Nick, Bob and Dave while we compiled the special 75th Anniversary issue. You can expect to see other retro articles throughout the coming year. GY

OIL AND PLUGS

I have been reading your "Thinking Big" column for several years, and I hope you can answer a few gas-engine questions for me. I just bought a new Zenoah G-26 and need to know which kind of oil mix to use. Also, how often should I check the spark plug, and what should the sparkplug gap be?

Jim Sullivan

Walpole, MA

Jim; the G-26 is a great engine, and you'll find that with a little care, it will last almost forever (barring any sudden impacts with the ground). When the engine is brand-new, I use an ashless, petroleum-based oil such as those offered by Ace, Agway and Lawnboy, and I mix it with the gas at a 40:1 ratio. After the first gallon, you can switch to a 50:1 mix ratio. After you have run four or five gallons through your engine (it can take that long to run in a gasoline engine), switch to a good synthetic oil such as Klotz or Amsoil. You can use these oils in ratios anywhere from 85 to 100:1. The newer synthetic oils do a great job of lubricating engine parts, and the higher ratio will improve performance. If you're just having fun, it's OK to stay with the less expensive petroleum oils.

I check my plugs for carbon buildup about every 20 to 25 flights. I set the plug gap at 0.025, but this really isn't critical. Some of my flying buddies set their gaps at 0.030 and 0.035, and I don't notice any performance difference. If you get a buildup of black carbon, however, don't be afraid to lean the high-end needle a little. Your plugs should be light brown; if they're light gray or white, your mixture is too lean. Good luck! GY

SERVO LOCATION

In your October 2003 issue's "How to Install a Gas Engine," the throttle servo is shown mounted on the firewall. I have been told that a servo should not be mounted less than 12 inches from a gas-ignition system because of potential radio interference. But some modelers have said that this isn't a problem. Did you use a fiber-optics isolator, or is interference not a problem? Thanks for your help.

Dave Asman

Sterling Heights, MI

Dave, I did not use any special equipment to install the throttle servo in the giant-scale Great Planes Pitts Special. The best thing to do when you set up a new model is to use whatever feels comfortable. For years, it has been accepted that keeping the radio gear as far away as possible from a gas engine is a good setup for minimal radio-frequency interference. If you have any concern about radio-frequency noise, go ahead and install your throttle servo in the fuselage, and use a plastic pushrod to connect it to the carb. This is still good advice. After many flights, I haven't found any problem with the Futaba Super 8 setup I used with the Pitts Special. Many giant-scale modelers who use modern radio equipment have found that gasoline-engine-generated radio-frequency noise is becoming much less of a concern, fust be sure to install your engine properly, use a resistor-style spark plug, and always perform a range-check with the engine running before you fly. GY

ENGINE BREAK-IN

I just purchased a new O.S. .46FX engine and need to determine the proper procedures for break-in. Looking through past issues, I found Dave Gierke's article from November 2001, and it is very clear. However, the O.S. manual gives a totally different method that includes running the engine alternately, every 10 seconds, from "4-cycle" to "2-cycle" through a full tank of fuel.

Mr. Gierke highly recommends that an ABC engine be run only in a rich 2-cycle operation, and his explanation makes a lot of sense. Does this hold true for the O.S. .46FX? Please help!

Robert E. Lee

[email]

Robert; I believe that your O.S. .46 is of the ABN type (nickel cylinder plating); therefore, it should be broken in as I have stated: short runs (2 minutes) at a slightly rich 2-cycle (never 4-cycling); allow complete cooling between runs (20 to 30 minutes will be sufficient); and the engine should hold a peaked setting without "sagging" (losing rpm) before it's ready to power your model. Have fun with your new engine! Dave Gierke