armody

My Feedback: (10)

Hi there all,

Last sunday I went to the flying field, and we had newly bought mixed fuel which is methanol+castor oil with us. A friend of mine brought his heli Raptor 50 of Thunder Tiger and flew it real good. As I mentioned earlier that we in Pakistan use only Methanol+Castor oil mixed like 80:20. 80 is methanol and 20 is castor oil. The mixture was somehow 75:25 which totally changed the attitudes of 3 engines. One was mine which is K&B .61, 2 were my friend's engine both O.S. .46 and .25 size. Both gave us enough dead sticks, and my plane didnt fly at all. Now I wanna ask couple of questions here.

First question is As it was said that an engine should be run rich, cos it would keep the engine cool, gives good RPM and it won't damage your glow plug, unlike this condition, lean fuel means hot engine, risk of damaging the glow plug and less RPM. My friend who flies chopper he says, he runs his engine lean as being lean it gives him high RPM, is it true that any engine which is run lean would give high rpms as compared to rich? or heli engine's attitude is different than airplane's engine? Furthermore running an engine rich means higher rpms right? and what is the advantage of getting higher rpms? good speed right? and good engine performance right? please clarify.

Second Question, As it was said that nitromethane or Nitro is used as a additive or a catalyst increases the action of combustion, thus engine runs with higher rpms as compared to the fuel without nitro. If the fuel ratio is changed as I mentioned earlier does it make any difference in engine running as we noticed or not? what is the price of Nitro pure nitro without any mixing per liter or per gallon in US $. The fuel we use here is good for the engines or not? If we use 10% mix of nitro, and after that we don't use 10% nitro mix, would it make any difference to the engine's attitude or not?

I would like to have the answers of all if you all respected flyers like to give me.

Thanks in advance[8D]

Mody

Mr67Stang

Changing the oil content of your fuel will sometimes require a change in the mixture setting. If you run the engine lean it will spin a little faster (higher RPM) untill it overheats and starts to move towards lock up and damaging metal scraping just prior to lock up. Now if you are using more oil in your fuel than before you may have to lean it some to get a propper run out of it. Just make sure you have that faint smoke trail coming from it and you will be fine. Remember if you have more oil conversley you have less stuff that burns.

The fuel I buy is 15% nitro content 18% synthetic oil which I bump up to 20% by adding natural castor. The gallon jug cost me about $16 USD. I am not aware of anyway to purchace any quantity of pure 100% nitro for self mixxing.

armody

My Feedback: (10)

Thanks Mr67Stang for the reply.

As the fuel we have is 75methanol & 25castor oil, I'd try to run it little bit lean and find out what happens this sunday.

Thanks for the info again

Mody

bigedmustafa

My Feedback: (2)

With regard to operating a 2-stroke airplane engine, the ideal needle valve setting for full throttle is slightly rich of peak. This will allow the engine to run at peak rpm once it gets in the air and the propeller unloads during flight. Running lean will cause the rpm levels to drop, overheating, and eventually engine wear/damage. I don't know enough about glow helicopters to say this with any authority, but I'd guess that helicopter pilots probably run their engines at peak rpm because helicopter rotors wouldn't likely unload in the air like airplane propellers do.

If you change the nitro content of your fuel, whether it be from 0% to 10% or 10% to 0%, you will need to retune the engine a bit. Additional nitro content will often increase the peak rpms of a two-stroke engine, but the difference isn't always significant.

Your original mix of 80% methanol and 20% castor oil should be ideal for most any modern engine. 25% oil isn't necessary and it will tend to retard your engine performance. Besides which, castor oil is normally more expensive than methanol, so it's cheaper to run 80/20 than 75/25.

armody

My Feedback: (10)

Thanks bigedmustafa,

This is exactly what happened that just slight 5% increase of castor oil retarded our engines, that is the mistake of that guy who provides us the fuel, or one of his worker must have done that, anyway, thanks for your informative reply.

Mody

downunder

Your 80/20 blend with castor is exactly the fuel I've always used for all my engines other than when running in I use the 75/25 mix. If you switch from the 80/20 to the 75/25 then you must retune or the engine will run a little leaner because the extra oil has displaced some of the methanol. Opening the needle (richening) gets you back to having the same amount of methanol going into the engine. It sounds to me that none of the engines were retuned when the new batch of fuel was used and so they all ran lean. Lean is bad but with castor there may not be any permanent damage done. Tuned properly you shouldn't notice any real difference in power between the two fuels.

Don't attempt to run it a bit lean like you said in the last post, open the needle until it's running obviously rich then tune as normal from there. Any time you have a change in fuels, whether it be in oil content, type of oil or nitro then you must retune.

piper_chuck

My Feedback: (12)

Here's the way I set the needle. It could be useful when you try the fuel again.

The following method is designed for sport flying where one wants reliable engine performance (minimum deadsticks) and long engine life (part of which comes from avoiding lean runs).

I’ll start off with a reminder that all needle adjustments should be done from behind the engine and that the plane should be firmly anchored or held. Never attempt to adjust the needle while holding the plane in the air. A small engine blip or wind gust could result in fingers in the prop.

Begin by gradually leaning the engine until you find the peak RPM. Once you find this, turn it several clicks rich. Once you’ve found this slightly rich setting, with a firm two handed grip on the plane, point the nose straight up. While you are doing this, remember to keep the propeller arc out of anyone’s face. When you raise the plane’s nose, one of three things will happen to the engine RPMs.

If the engine speeds up slightly and holds that speed for 10 to 15 seconds, pat yourself on the back (after you put the plane down), you’ve got the needle set pretty well.

If the engine slows down, or does not speed up a bit, it’s too lean. Lower it immediately, turn it a few clicks richer and try again.

If the engine speeds up significantly, it could probably be a bit leaner. Put it back down, set it a bit richer and try again.

That’s it, no magic…

ABELL

nitro in the US is $1200.00 for 55 gallon drum or about $22.00 per gallon

armody

My Feedback: (10)

downunder, piper chuck and ABELL

First of all thank you very much for such an information and ofcourse the settings you told me, I know it, I have been told by many senior flyers, also the pinch test, well, I must thank you all again for some useful advices. ABELL I like to thank you for letting me the price per gallon of nitro. downunder your advice seems to be pretty useful, we did lack some tunning, and infact engine's behaviour was changed too, but this sunday, Im sure something is gonna be done good, as Im gonna do as you advised as well as piperchuck advised. We keep our faces off the arc, don't try to hold the plane easy, yes, it may chop our fingers off, and the flyer I fly with is senior one, and he does listen to me cos I come on rcuniverse and get great advices from great flyers like you all guys and other guys who always reply to me.

Happy flying

Mody