Author: Mark Fadely
Edition: Model Aviation - 2010/02
Page Numbers: 113,114
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Radio Control Helicopters

Mark Fadely [[email protected]]

Indoor flying is in full swing

Hello, everyone. Can somebody please high‑five me for the fact that we have indoor models today? In the middle of winter I always ask myself, why do I live in Indiana? Remembering that the National Flying Site is just minutes away takes the edge off my depression.

I'm envious of all those pilots who live in warm climates. I guess you will never have the thrill of flying off a frozen lake in your hometown. Did I use the word "thrill"? I didn't really mean that.

That is enough about my geographical anguish. It is time to cover helicopters. Indoor flying is in full swing. As I am writing this, Jay Smith (MA's assistant editor) is working on a report about the 2009 JR Indoor Electric Festival in Columbus, Ohio, held November 6–9, 2009.

The inflatable dome where the event was held collapsed awhile back and the festival had to be canceled. This is the first year the gathering was held in a new, larger dome. Jay will have a full report on the event. I hope many of you were able to attend. The JR Indoor Electric Festival kicks off the indoor flying season. Check the website and make plans to attend the 2010 edition.

You might receive this issue before the Great Planes E‑Fest takes place in Champaign, Illinois. It is scheduled for January 30–31, 2010. This is the biggest indoor event of the winter, so if you can make it out for this one, it will be worth the effort. Helicopters are welcomed at this get‑together. E‑Fest is mostly about having fun, hanging out, and flying with your buddies.

Fuel-System Setup for Nitro Helicopters

A number of pilots ask, "What is the best way to set up the fuel tank on my nitro model?" There are several options available to deliver fuel to your engine with good consistency.

When a helicopter is in 3‑D flight, G‑forces cause the fuel inside the tank to move in all directions. Imagine that you are mixing lemonade: you put the top on the pitcher and shake it for a few seconds. Now think about your helicopter doing the same thing with its fuel tank. As pilots, we expect our fuel systems to perform flawlessly while our helicopters fly in all orientations and speeds. That is no easy task. Let's look at some fuel‑system setups.

  • Muffler‑pressure setup: A line runs from the muffler to a tap on the fuel tank. When the engine is running, exhaust pressure is routed into the tank to help feed fuel to the carburetor.
  • Pumped setup: A pump with a regulator is installed in the fuel line before it reaches the carburetor. The pump generally meters fuel more consistently as the tank empties.

The fuel clunk inside the tank is one of the most important parts of the system. For many years, clunks have been made from a weighted metal designed to flop to any part of the tank, following the G‑forces. That works well, but the recently designed OMI Fuel Magnet works even better.

The Fuel Magnet does a wonderful job of getting every last drop of fuel out of the tank and holds a reserve so the engine won't quit even if the clunk is temporarily not drawing fuel. James O'Neal of O'Neal's Manufacturing, Inc. (OMI) developed the product. It is basically an aluminum insert with an inlet hole that slips inside a small foam doughnut. The foam soaks up fuel and becomes saturated. When soaked, it is heavy and moves around inside the tank with G‑forces much like a traditional metal clunk.

While it works well, be aware that the foam is sensitive to exhaust gas. If you are using muffler pressure in the tank, you must be careful not to leave the Fuel Magnet exposed to hot gases after a flight. You can remedy this by refueling the tank after a flight so the foam Fuel Magnet remains submerged and is not affected by exhaust gases.

I still use the old‑fashioned main/header tank setup on some helicopters. It is a proven system that never seems to go out of style, and several top pilots still use it. A header tank uses the larger main tank to feed a small auxiliary tank that feeds the carburetor. The header tank will retain enough fuel, even when the main tank occasionally takes in a little air.

It is difficult to get a tank set up so the clunk will always draw fuel. There will be certain positions the helicopter can get into that cause the fuel system to momentarily run dry. This does not create a problem for the header‑tank approach or the Fuel Magnet. Although the OMI Fuel Magnet has no header tank, the foam sponge clunk retains fuel and continues to feed the system in the event it draws air. It is an ingenious invention that works.

Check your fuel system carefully, and change it if it gave you problems last season.

I hope everyone enjoys the rest of the indoor flying season. Don't neglect your outdoor models that are sitting on the shelf. A little attention to preparing them for the new season will pay dividends when the weather breaks.

See you all here again next month. MF

Sources

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