That applies to two-stroke engines. A two-stroke can be tuned by ear pretty easily for most people. Most people can't, however, tune a four-stroke by ear. That's why many people buy tachs. They're handy for some things, but the only place they're really a necessity is with a four-stroke.
They are handy, but not a necessity.. at least, not in my limited experience. I have owned a Saito 82a for about 4 months now, so I'm by no means an expert. However, I do not own a tach and have flown approximatly 7 gallon of fuel with it, without any problems besides the ones I created myself. It seems you have to actually fill a fuel tank before take off. No one ever told me.. Duh!
I did however use a tach (lended) for comparing props and I am planning to buy one. I have no doubt a fourstroke will be better tuned using a tach, but I wouldn't call it a neccesity.
ORIGINAL: Flying freak
Ok i am not very experince but how can our model engines idle all tank long..I mean the oil will accumulat after some time and end up pooling there and the rpm will drop..
The oil will accumulate where?
He's talking about the oil/fuel mixture. Oil is the lubricant, methanol/nitro/gas/whatever is the fuel