R/C AIRCRAFT
Fuel—Ask the Experts
Horizon Hobby Distributors is one of the world's finest distributors in the radio control industry today, supplying hobby shops all over North America with the best the industry has to offer. The nice people at Horizon have given us permission to reprint the following article from their Ask the Experts column of Product Focus publication, May, 1996. Expert advice on model engine fuel provided by Don Nix of Powermaster.
Some Answers about Fuel . . .
We get dozens of calls every month asking questions about model engine fuel. These are amoung the most frequently asked:Q: What's the shelf life of fuel — how long will it stay good?
A: Glow fuel will last almost indefinitely if it is protected from contact with air as much as is practical. Most often, fuel is "killed" by absorption of moisture from the air. Unlike gasoline, mehanol — the primary ingredient in fuel — is hydroscopic and absorbs moisture aggressively. A container of fuel left slightly open for an hour in humid weather will be pretty well ruined.
Q: How can I know if my fuel has absorbed too much moisture? Is there a simple test I can perform?
A: The "simple test" is to run the fuel. The first sign of moisture absorption is an inability to obtain a normal idle — or any idle at all. Typically, the engine will be difficult to start and will die, or it will begin to run roughly as soon as you remove the glow battery. To verify, drain the tank, fill with fresh fuel, and restart. If the engine runs smoothly, then there's little doubt that moisture's the problem.
Q: Why doesn't someone invent a pill that can be dropped into fuel to absorb all the moisture, such as the little moisture absorbing packets packed with alot of products?
A: A wonderful thought. Unfortunately, it's not possible. Methanol is 100% soluble in water, and short of an expensive distillation process, there's no way to "unabsorb" it.
Q: What can I do to protect my fuel?
A: Keep fuel tightly sealed and minimize air space in the container. Open only when necessary and keep all tank vents sealed (hook the filler and pressure lines together after each flight with a short piece of tubing). Plastic keeps fuel better and longer than metal, and the containers don't rust. If you do use a metal can, replace it from time to time to prevent corrosion.