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Is there a chemist in the house? - 12/17/2002 9:54:24 AM   
hauckf


 

Posts: 188
Joined: 3/1/2002
From: Decatur, AL, USA
Status: offline 		Help! I've searched the web and a university library trying to find the coefficients of cubical expansion for methanol, nitromethane, and polyalkyleneglycol (synthetic oil), but so far have had no luck. Can anyone out there help me out, or suggest where I might look for this information?

< Message edited by hauckf -- Dec 17 2002 10:51PM >
       Post #: 1

H202p3KN72 - 12/17/2002 10:33:43 AM   
Cleared4Crash



Posts: 175
Joined: 11/29/2002
From: Illinois
Status: offline 		Whoooowhaaaaaaat???

And you need this info because??

Maybe an MIT prof or U of IL professor can help ya with that one.

All I know is that my Pepsi has bubbles...and bubbles are gooooood.

(in reply to hauckf)
       Post #: 2

Is there a chemist in the house? - 12/17/2002 12:13:05 PM   
hauckf


 

Posts: 188
Joined: 3/1/2002
From: Decatur, AL, USA
Status: offline 		Ya, I figured I'd catch some flack on this one! The reason I want to know is: A certain glow fuel manufacturer claims that because volume increases as temperature increases, the ingredients in the fuel must be measured by weight , not by volume when mixing the fuel to get a consistent blend. Just for fun (yes, I think stuff like this is fun) I thought I'd run some numbers to see for myself, but to do that, I need to know the coefficients of cubical expansion for methanol, nitro, etc. I became interested in this from reading posts about this particular manufacturer on this forum.

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       Post #: 3

Fuel - 12/17/2002 5:22:41 PM   
Homebrewer



Posts: 1335
Joined: 12/29/2001
From: Colorado Springs, CO, USA
Status: offline 		Yep, I'd be interested to know whether or not Byron fuel's claim that mixing by weight is more acurate than mixing by volume.

I suspect if you were mixing 2,000-3000 gallon batches at a time, you'd probably notice a temperature effect.

(in reply to hauckf)
       Post #: 4

Is there a chemist in the house? - 12/17/2002 8:48:24 PM   
downunder-RCU



Posts: 1125
Joined: 12/27/2001
From: Adelaide, South Australia
Status: offline 		I've wondered when someone was going to ask this. If Byron (or anyone else) came out and said that they mix by weight so as to get the equivalent of a certain volume at 60F then I'd have to say it was more accurate. But it seems that some people have done evaporation tests on certain brands that are mixed like this and the results for oil have come out way below the stated percentage when converted to volume. And nitro is even more dense than oil so there'll be even less VOLUME of nitro. So just to repeat, IF they said that their mix by WEIGHT was to give the equivalent % VOLUME at 60F (or 70F...or whatever) of the various ingredients then fine.

Personally I suspect that given the relatively narrow range of temperatures we use our fuel there wouldn't be any noticeable difference in volumes so it's just a way of making cheap fuels.

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       Post #: 5

Is there a chemist in the house? - 12/17/2002 9:52:21 PM   
Ross Kean



Posts: 686
Joined: 6/4/2002
From: Fredericton, NB, CANADA
Status: offline 		As long as the manufacturer has appropriate equipment to accurately measure volume or weight, it really shouldn't matter how the fuel is formulated. One would assume that the fuel specs are based upon volume at some standard temperature. Otherwise, 10% nitro by weight is substantially less than 10% nitro by volume since nitro is denser than methanol or oil at all temperatures. One would hope that they have enough smarts that they would correct for differences in material density as a function of temperature if they are mixing by volume. In short, it doesn't matter how the fuel components are measured as long as they are including appropriate density factors.

I would be much more concerned about the inclusion of an appropriate quality control protocol. This would include raw material quality specs and batch testing of finished product. I would also want to see a list of the compositional specifications (i.e. tolerances for acceptance intervals of individual components). Quality testing of finished product should also include concentration of contaminants (especially moisture and ash residue). You might also look for oxidation byproducts, acidity, chloride, nitrates etc. Even to say that the fuel contains a particular amount of castor or synthetic oil is not sufficient - not all oils (either castor or synthetic) are equal. I am a chemist and when we purchase pure chemical reagents or mixtures for the laboratory, the material specs including assay of major components and impurities are critical.

Ross

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       Post #: 6

Sha boom sha boom - 12/17/2002 10:26:09 PM   
Cleared4Crash



Posts: 175
Joined: 11/29/2002
From: Illinois
Status: offline 		Y'all gonna be mixin' up 2-3000 gallon batches?? Boy you guys do a LOT of flying.

As long as that engine starts, I don't give a hootie if they mix it while dressed in feathers and dancing the nitro dance.

But all this got me ta thinkin'. I better check that Pepsi can. Hmm...says 12fl oz......yep....got 12oz....hmmm..but wait...the bubbles are displacing some of the volume....hmmm...I think I'm getting ripped off! Holy molybdenum batman! I'm writing a letter to Pepsi right now and demanding they supply consumers with 12.00256978fl oz in each can!
POWER TO THE PEPSI DRINKERS!!

(in reply to hauckf)
       Post #: 7

Is there a chemist in the house? - 12/17/2002 10:42:02 PM   
P-51B



Posts: 6173
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From: An Iceburg in, ANTARCTICA
Status: offline 		Measuring by weight is more accurate for a given location as you don't have to worry about the temperature variations.

Although I have only heard of the desired information referred to as coefficient of expansion, you should find what you need in either the CRC handbook or the CRC handbook for materials engineers.

_____________________________

In order to think "outside the box", one must first accept there IS a box.

(in reply to hauckf)
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Is there a chemist in the house? - 12/18/2002 12:39:56 AM   
hauckf


 

Posts: 188
Joined: 3/1/2002
From: Decatur, AL, USA
Status: offline 		Thanks for your replies. I really didn't want to get into discussing any particular fuel brand, but since you brought it up ... I think downunder has hit the nail right on the head. The fact is, the percentages that Byron lists for the ingredients in their fuel are by weight, not volume, as Ross and I'd guess many others "would assume". That means, as Ross and downunder state, that the actual percentages by volume for the nitro and oil in Byron's fuel are less than the percentages listed on the label because nitro and oil (both synthetic and castor) are denser than methanol.

But it isn't the mixing method that I find questionable. Mixing by weight probably is more accurate as Byron contends; just how much more accurate is what I am trying to figure out. Its the labeling that I question. Virtually every other manufacture lists the percentages by volume. If I buy fuel that says "18% oil" on the label, I expect 18%, not something less. Burning fuel with less nitro might reduce performance; not a big deal, that's something I can see. Burning fuel with less oil on the other hand might reduce engine life; definitely a big deal since it is not readily apparent. I think it would be wise for all of us to "give a hoot" about that. I'm definitely not saying that burning Byron fuel with less oil by volume is damaging engines! I do believe, however , that the potential is there, since many engine manufacturers recommend a minimum of 18-20% oil by volume. And yes, I wholeheartedly agree that QC is very important, and that all oils etc. are not created equal, although it is my understanding that the sythetics in glow fuel are mostly polyalkyleneglycol derivatives.

P-51B: CRC is the first place a looked. I also looked in about a dozen other reference books at a university library with no luck. Apparently, it is not a commonly used spec and is not included in most reference books.

STILL LOOKING FOR THOSE COEFFICIENTS PEOPLE!

< Message edited by hauckf -- Dec 17 2002 7:53PM >

(in reply to hauckf)
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Is there a chemist in the house? - 12/18/2002 12:53:59 AM   
P-51B



Posts: 6173
Joined: 10/11/2002
From: An Iceburg in, ANTARCTICA
Status: offline 		Sorry, I thought the CRC materials handbook surely had them (this is not the standard CRC). I no longer have a copy. I will see if I have them in any other materials books, if I do I will let you know, if not I won't!

One other place you may look since you are near a university, is in the chemical engineering section of the student book store. Somthing may turn up.

_____________________________

In order to think "outside the box", one must first accept there IS a box.

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splitting hairs - 12/18/2002 2:53:52 AM   
Cleared4Crash



Posts: 175
Joined: 11/29/2002
From: Illinois
Status: offline 		How many people here who have been flying RC for a long time ever had a seized engine due to lack of oil in a commercially produced fuel...AND can prove that it was in fact the lack of oil in the fuel that caused said siezure?? "Lack" meaning the stated amount of oil in the bottle was more than what was actually in the bottle. And please tell us how you determined that there was indeed less oil than was stated on the label.

How many people here have had ANY engine FAILURE related to lack of oil in a commercially produced fuel AND can prove beyond a shadow of a doubt that it was this lack of oil that ultimately caused the failure??

Anyone?? Raise your hands please.

For those who think they are not getting enough oil in their fuel mix, or think they are getting 17% oil instead of 18%, feel free to add more if you so desire.

For those who believe it's a government conspiracy designed to eliminate the entire RC modeling business, please only fly while wearing a special tin foil suit.

Hmmm...come to think of it, I think manufacturers are overstating the torque rating on their servos. I demand and inquiry into the missing oz/in...or is it in/oz.....well in any case, there is a missing torque mystery afoot!!


(in reply to hauckf)
       Post #: 11

Is there a chemist in the house? - 12/18/2002 4:26:29 AM   
hauckf


 

Posts: 188
Joined: 3/1/2002
From: Decatur, AL, USA
Status: offline 		Byron's 15% nitro, 18% oil Premium fuel contains about 11.3% nitro and 15.6% oil by volume. If the users knows that when they buy it, fine. My guess is that many don't. As far as I know, Byrons is the only manufacturer that lists the percentages by weight. Morgan, Wildcat, Red Max, Powermaster, S&W, and Coopers, to name the ones I've checked on, are all by volume. Now, how about this question: How many of you out there have seized or worn out an engine or bearings and can prove beyond a shadow of a doubt that it was not a lack of oil that ultimately caused the failure? Anyone? Please raise your hands.

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A slippery subject - 12/18/2002 8:59:31 AM   
Cleared4Crash



Posts: 175
Joined: 11/29/2002
From: Illinois
Status: offline 		Tooooshayyyyy

Nobody is chiming in with their stories of engine failures yet. I guess we will have to wait a while for news of this topic to spread like a grease fire.

But if average joe modeler buys said gallons of fuel containing less than stated amounts of oil, and unwittingly enjoys years or even decades of use from various engines with nary a problem, is he really going to be concerned that the actual quantity of oil is less than was listed on the label? If engines suddenly started siezing around the globe by those using a particular brand of fuel, then maybe there could be a link. I'm all for truth in labeling. Maybe the manufacturers should put something like...."contains 15% oil +/- 14%?? Or maybe they should just put, "has its fair share of lubricants." Or maybe they should add no oil and let the modeler add the desired amount?? So many questions...too little time.

Or maybe it was bad metallurgy during the design and manufacture of the engine....or maybe it was bad maintenance habits by the owner....or maybe it was the salts in the air along coastal areas...or maybe the stock fuel was "adjusted" by the modeler to make it "better".....or maybe the engine was stored long term improperly...or maybe the tolerances during manufacture were not adequate for the intended use....or maybe...............................

I pump gas in my car each week. The heck if I know what the formulation is...and frankly I don't care. My car starts and I'm on my way. If and when I see the station full of cars that died after being fueled, then I guess I would fill up somewhere else.

How do you know when you by a quart of oil for your car that you are getting x y z percentages of additives? You don't. Well...maybe you do....but I don't. There is an implicit "fitness for a particular purpose" when we buy gas, oil, model fuel, etc. That when we buy these products, they will essentially do what their intended job is without causing a major engine failure or excessive wear.

Maybe manufacturers are fudging for marketing purposes? Maybe they are trying to pinch pennies? Maybe they have poor quality control? Maybe they didn't figure anyone was going to check?

Is it really a problem? My hunch is no. I think there would be quite a few reports of problems when using a certain fuel brand.
And is it THAT critical in a model engine if the oil content of the fuel is a bit one way or another? We aren't launching the space shuttle here. I'm perfectly content buying commercially available fuel and using it as is. Maybe I like to live on the edge.

Food for thought anyway.

I'm just playing the devil's advocate here....as I tend to do sometimes.

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Is there a chemist in the house? - 12/18/2002 9:30:10 AM   
Steve Guinn



Posts: 835
Joined: 8/23/2002
From: WV
Status: offline 		I Think C4C flies alone!

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Is there a chemist in the house? - 12/18/2002 10:15:08 AM   
downunder-RCU



Posts: 1125
Joined: 12/27/2001
From: Adelaide, South Australia
Status: offline 		Well I'm amazed at how some guys apparently are willing to accept being shortchanged on oil and nitro compared to other brands. Is it brand loyalty? Imagine buying a 46 engine then one day someone measures the bore and stroke only to find it's a 40 but the manufacturer says "Oh well, we measure it differently by including the combustion chamber volume so it's a 46".

Using a fuel with less than the manufacturer's recommendation may not necessarily do immediate damage but how does it affect the life of the engine? Any engine should run for hundreds of hours but how many times do you hear someone saying that their engine finally wore out after 50 hours so it's time to buy another?

(in reply to hauckf)