quote:

ORIGINAL: HARC_PT

ok!

What do you guys think about this:

Ethanol - 70%
Benzene - 5%
Acetone - 5%
Synthetic Oil for 2-stroke engines - 10%
Ricin Oil - 10% (= castor in english )



Running through this list the first one Ethanol causes a serious problem in most of Europe as ethanol 100% is the drinking liquor Alcohol and most countries insist that it is changed to 95% ethanol and 5% methanol to make it poisonously for drinking purposes the term I think is denatured or methylated spirits so that they can tax the beer drinking humans who consume small quantities mixed in with in their drinks like beers and wines etc

Ethanol is often double the price of methanol and usually only medical hospital operators with special license can purchase 100% pure Ethanol a semi toxic to consume product as in when we all get tipsy from drinking to much beer but toxic and dead from drinking to much moonshine liquor


Most all RC fuel uses methanol a extremely toxic for life forms to consume alcohol even in small amounts and also like ethanol and other types of alcohols burns well in internal combustion motors due to the fact that half the molecules of Alcohols contain oxygen molecules in their make up ensure extra hot flames

Power tends to be marginally better from ethanol and marginally more MPG or longer fuel runs for same fuel tank but if it costs too much the advantage is negated from using ethanol
The ethanol has slightly less oxygen on the molecular make up than methanol so more carbon molecules to burn

However due to peculiar rip off policy from methanol suppliers in Europe it is sometimes cheaper to source ethanol over methanol

As 99.999% of the RC community uses methanol you would be forging new frontier experiments using ethanol and unlikely to worth the effort for a small RC 2.5cc motor but all reports suggest it is possible to use ethanol if you can find the correct glow plugs to work with it (often hot types glow plugs seem to be what works best according to several other threads in this fuel forum)


Benzene is often the the word that half of Europe uses for petrol and what the USA calls gasoline abv GAS and the other half of Europe calls petrol

True benzene is a totally different product and i suspect that the formula refers to the fuel Gasoline petrol instead

This was common practice with 1960's model fuel formulations to use some component of Petrol benzine gasoline whatever (shall call it gasoline for now) to help motor run times

This is because gasoline products have no oxygen component on the molecules and as such will need twice as much air to burn as methanol products that have already got 50% oxegen component but then you get twice the MPG or twice as long engine run for the same fuel tank with gasoline as you get your oxegen from the air instead of carrying it on the fuel

Problems are gasoline burn very very hot and often has knock unwanted affects and wont atomize so well in micro motors resulting in rough running and difficult to tune affects and a 20% power loss compared to methanol fuels so making 100% gasoline less interesting for motors less than 50cc where large metal mass for cooling and large carbarators can use 100% gasoline well

Metal cooling surface area affects kick in harder on smaller motors so not allowing motor even with huge cooling fins to be kept cool with motors below 50cc using gasoline as an example just look at relitivly huge cooling fins on small gasoline 50cc motors compared to larger automobile VW air cooled 1300cc gasoline motor and compare them to smaller cooling fins on glow motor even helicopters and model cars and buy the time you get to 10cc its not realisticaly feasible to make cooling fins large eneogh for gasoline versions

5% gasoline mixxed into glow motors fuel might be more possible on 5cc upwards but could easly melt small 2.5cc motors already on the ragged edge of dumping off heat build up

The ideal sized piston chamber for gasoline power and MPG is between 250 cc and 350cc so explaining why most cars use 300cc cylinders

Below 10 BHP or 8KW gasoline engines lose effiency fast

The ideal sized piston chamber for methanol is much smaller than gasoline or ethanol making methanol the logical fuel for micro motors

Also as Methanol uses twice the fuel for each piston stroke than gasoline there is more liquid vaporizing which helps keep the micro motors cooler for various reasons of thermo dynamics

Acetone is a sorta replacement agent for nitro in that is reals purpose is not so much to be a fuel but to help the Methanol fuel burn more correctly which makes it easier to tune the motor(it make affects the flame of methanol so it lasts longer similar as nitro makes flames last longer in the down stroke of pistons

Synthetic Oil for 2-stroke engines - 10% ( is a bit vague and a banana to slip on )
Synthetic Oil there are roughly two types for model motors one type that mixes well with gasoline but not well with Methanol and the other type that mixes well with Methanol so for our purpose the methanol type is what we want and often this only obtainable from RC model shop outlets like LHS or on line and cost a lot more than Synthetic Oil for 2-stroke engines for gasoline motors like scooters and motorbikes outboard motors etc and then there are huge schools of thought on the differnt types of Synthetic oil and affects at high tempertures accept to say even low nitro content cooling affect can help reduce Synthetic oils from burning up if you run the engine too lean or similar

Most model fuel in LHS or similar in Europe will be 100% Synthetic Oil as Castor is considered a nuisance oil for lots modelers as it gums up motors in various ways and often most LHS wont even sell Castor oil lubrication fuels as there is little or no demand for it or market forces whatever from magazine jornals have run castor oils out of town mostly on mainland europe ( but pockets of resisance still hold out stubornly in UK where castor seemly is still the majoriy fuel but this is probably due to higher costing methanol issues and more price sensitive users than any reason I can think of.)

Synthetic Oil because it works so very very well (yes I am seriously biased ) often instead of using 20% Castor oil we can replace it with suitable Synthetic Oil like Klotts etc at 18% or even lowwer than 15% there by getting more fuel to burn instead which is very interesting for power

Japanese helicopter competitors user have access to even better oils that they dont sell to joe public and can go as low as 10% with no castor with no problems of wear heat or any other issues

Ricin Oil - 10%

Proffesionals will often mix in 2% Castor with 18% Synthetic Oil to get some of the benefits that (ricen) Castor can give
but 50% Castor and 50% Synthetic Oil combinations exist and can also be popular in certain applications more often found in model boats glow motors

Most RC 2.5cc cars will operate very well on 18% Synthetic Oil so that is the usual solution but 20% Castor will work well also and 50% mix of the two will operate well also at say ~20% but then you need to use after run oil in your motor and clean motor much more frequently if the castor is 100% or high % ratio

Castor oil is sometimes cheaper depending on your part of the world but the Castor oil for RC motors is often special in that it has extra ingredients that stop unwanted affects like ash build up etc and often it is difficult to get these Castor oils from LHS on mainland europe as they don't want to know this problem as its expensive importing it just for one offbeat customer when 90% plus modelers are using Synthetic oils

Major and large model plane clubs in Europe will often have a drum of this castor oil and will sell it to RC modelers as the FAI fuel is 20% Castor 80% methanol but even that become rarer as time passes

Model boat clubs seem to stock castor also as its cheaper than Synthetic Oil engines and it often saves motor from seizing up so they get partial seizes instead from protection of Castor but model planes more rarely seize up due to more airflow cooling benifits

Car clubs don't seem to like Castor oil burners mayby because its more smoky or makes a more permanant difficult to remove oil stain on the tracks or smell of chip pans makes them hungry but really not sure what the story with them is




And finally the Nitro issue that has everybody going ape over

YES wiki is sorta wrong
Nitro is not a really good or suitable mono propellant for either models rockets or drag cars or RC model motors but is a useful (sorta) fuel in several applications

Without getting way to deep into the nature of using nitro as a fuel its best to understand the simple basics ( which this will probably stir the proverbial pot ) but here goes try to make a complex problem simple

For simplicity I will use a 100% nitro fuel example which for the real world is nearly impossible;e to do and 85% nitro is the generally the highest ever done in drag cars and even NASA and USSR gave up trying to make 100% nitro work in rocket motors for lots of reasons to much to explain here



Nitro has a lot of oxygen and nitrogen molecules attached to it fairly small complex carbon molecule structure
This means as a mono propellant it is in theory able use its own oxygen to burn and will only need a small amount of extra oxygen to complete the burn leaving some excess carbon behind if there is no extra oxegen and in a bi -propellant scenario where it is 100% nitro and mayby 5% oxygen or 20% air whatever the excess carbon will burn making a complete burn and is nearest thing to liquid oxegen without the problems of bottled up frozen liquid oxegen or LOX

If you chose to use nitro at 100% with a small amount air you would need 9 times as much fuel to do the same job as methanol fuel burning with a lot more air or considerably nitro more than gasoline and as Nitro is typically 10 times the price than methanol this makes using g !00% nitro approximately 25 times more expensive to use than methanol and 100 times more expensive than gasoline


This effect is more easly understood from something called stoc ratio or air oxegen fuel ratio
nitromethane.... 1.8:1
methanol .........6:1
gasoline ...........14:1

Gasoline with no oxegen on carbon complex molicule needs 14 parts air to burn for one unit of gasoline or 2.8 part oxegen to one part fuel
methanol with 50% oxegen on carbon complex molicule needs only 6 parts air or 1.1 part oxegen to burn one unit of methanol
nitromethane with large amount of inert nitrogen and ~60 oxegene with little carbon complex molicule to burn needs 1.8 parts of air or 0.35 part of oxegen to burn one unit of nitromethane and uniquely in mono prop elant senario can burn and use ~80% of the fuel without extra air or oxegen leaving behind unburnt carbon molicules (but require crazy high pressures and heat to do mono prop)

because with 100% nitro you throw in huge quantities of Liquid you often don't need any other cooling systems even though you produce more than twice the power than methanol equivalant fuels as the liquid fuel cools the motor by drawing the heat away from the metal
to give an idea of just how expensive nitro is
If your ~20 MPG normal gasoline car used methanol you would get ~10mpg but 20% more power
The same car on 100% nitro would have easily double the HP but would get 2 MPG and at $100 a gal for nitro makes that $50 a mile EEEEKKKK

The whole car would have to be a fuel tank some few hundred gallons to go 500 miles distance like a gasoline version would go with 25 gallons tank but you would be able to go a whole lot faster than gasoline version

From this simplified explanation it seems that we get extra power from using nitro and the higher the nitro the more the power meaning model cars users often go for 25% nitro which might give them ~30% more power but probably ~double the fuel consumption

The ~doubling of fuel entering motor will help motor to keep cooler which has benefits for oil lubrication as well

Also because the nitro in low amounts like 25% will as it starts to burn releases large amounts of oxygen and nitrogen gas before it even starts to burn up this will have the affect of raising the compression in the motor and giving more power similar to a turbo charger without the weight and complexity of super chargers or turbo chargers

This will often mean the motor will be easier to tune as the nitro is a bit of a slow burn fuel and makes tuning easier
however in most model motors the majority of the still burning nitro is ejected into the exhast stack so its the compression affect that mostly counts

However to get the full benefits of nitro is difficult and most engines reduce the compression in the motor knowing high compression affect will be restored using high nitro thereby reducing benefits from Nitro


Other motors which will not use nitro will have very high compressions and use METHANOL and will due to this very high compression get nearly the same power as 25% nitro fuel motors that use lowwer compression and high nitro but zero nitro high compression motors will be more tricky to start and more tricky to tune but will be probably more than half the cost in fuel to use
Coupled with tuned pipes and correct design motors with no nitro and small amounts of acetone for smooth tuning it can be a lot more popular in countries outside the USA wto opt for zero nitro as nitro is often extremely expensive often more than double the price of USA outside of the USA


However speed costs money and winner takes all and the fuel tank in a 2.5cc RC car is small and fuel cost of 25cent per tank with zero nitro compared to 50 cents with 25% nitro and extra acceleration ease of tuning and smooth pick up on wide band pipes means for small RC car users they can often tolerate the extra costs of using nitro

For RC planes with 10cc engines or helicopters the use of 30% nitro can nearly quadruple fuel costs and put you in the poor house fast and and so changing motor to 90 size with tuned pipe and zero nitro or low nitro 5% will only double fuel costs so making it more logical to avoid high nitro contents fuels and opt for bigger motors instead to get more power



Most model planes in Europe will opt to use low nitro fuel 5% more for the smooth engine tuning benefits rather than for power reasons as although acetone does the job often as well and often cheaper the acetone can evaporate from the fuel more easily


The fact that Nitro is a high oxygen fuel with a high nitrogen molecule content that dosnt really burn fully inside the RC motor chamber in fact most is ejected while still burning means that from a practical modeling motor point of view its not really acting the fuel part like methanol is and we are using its side affects of smooth running FROM FLAME AFFECT and cooling benefits and increased compression affects as it disintegrates into gas state molicule component parts more than its fuel content component and as such is barely a fuel in the definition of our RC model motor needs and is more close to acting like a liquid air injection system to enhance methanol burn so explains why It would seem for modeling terms to classify it as a liquid oxegen component but others might disagree quite strongly

So to bring a little more balance to the nitro fuel term

In other uses Nitro mono propelant experments it can be a fuel like 1947 trials with early NASA rockets where slow flame ejection and other issues made it redundant to other solutions

In drag racers where they often use 85% nitro and 15% methanol sometimes higher nitro contents in the past before new rules max 85% and they generate 6000 BHP plus from a 90KG motor getting nearly 600hp per one KG of motor and effectivly melting the twin 70 amp spark plugs after 4 seconds and are deiseling the motor for the remaining few seconds then nitro is more of a fuel by definition of fuels and to get the extra air in they need to divert 800 hp to the Blower ( super chargers ) to cram more air in so much so that its nearly liquid air and liguid fuel in the chambers
and more close to rocket fuel solutions and has very little resemblence to most RC modeling needs where nitro is really used to make life easier to tune RC motors so nitro is a major fuel burning component in some situtions and a very very minor fuel burning component and major liquid air injection solution in other senarios like RC motors

Budget RC cars users will opt to increase compression on the motors use 5% nitro and use 20% Castor fuel to get better perfomance using skimmed heads or thinner or lessor no head gaskets solutions

Racer cars RC types to win will often use 16% nitro content European measure(25% USA measure due to Europeans and Americans measures systems are different when you do it with Volume measure versus fuel weight measures the fact that nitro is a relitivly heavy fuel at 1.1 compared to water means volume measure and weight measures will be different for same fuels rough rule USA nitro % fuel is 1/3 higher than European measures so 25% nitro USA is 16% nitro content European measure )





Thats the simple theory and the practice is that 98% plus of modelers just find it so much more easier to buy a gallon (IMP) (or 1.2 gallon USA measure or 5 liters) can of the fuel from a LHS even if its twice the price of making at home it as on small motors of less than 4cc fuels costs even with high 16% european measure nitro or 25% USA nitro are fairly low compared to other factors like breakages of parts from crashes


In large models with motors often exceeding 15cc or 0. 90cu inch sizes or if you have to travel 200 miles to LHS or if home delivery costs of fuel to some out of the way small village or farm whatever are orbital then making fuel can be a more interesting possibility but that rare eneogh

Honestly in Spain I never found any major problems to locate standard low nitro synthetic fuel in any town of 200,000 plus habitants and in my travels in Portugal I found that it had most everything Spain had OK more expensive than Spain but they had it on average but I wasnt looking for RC fuel that time so cant say for certain what the story is in Portugal

I gave up making my own fuel in France in 1995 after umpteen years making my own witches brews as I found that the fuel was often going bad not knowing at the time that methanol soaks up water from the air and it becomes useless as engines start acting up from water ingestion issues
The problem when French is not your mother toungue you dont pick up on the fine details like ( D'Leau et Methanol et hydroscopic il besion atrappe d'leau )or methoanol sucks up water from the air when the cap is off the bottle and makes it useless for RC glow motors really fast

I found that even with my 20cc (120 engines and 108 and 90 engines ) that my fuel use cost benefit ratio factors on simplex acrobatic and often cruising around on 1/3 gas that the LHS prices were tolerable especially once I moved to a town with no storage facilities for fuel and mixxing could be done

Most housing insurance and car insurance wont allow storing of fuels exceeding 1 gallon so I had to store one gallon in the car one in the apartment maximum so storing the 5 gallons I needed minimum buying the materials become impossible to do so I stopped making my own

In one French club I was in they had on average 100 gallons of methanol and 20 gallons of gasoline in the club house and you could mix your own gallon to your own formulas as you needed it but that was exceptional for a club as they had a Steel container hut on municipal waste ground that was in nowhere ville well away from the town so if it went Kapow no big deal

Anyway there also does exist other nito methane replacements something like nitro ethane whatever that have less oxegen and Nitrogen molicules than nitromethane and have other features like more toxic more difficult to make it vapourize or flame whatever but acetone is cheaper easier and more readly available than most nitros fuel products

dont forget metanol soaks up water from the AIR REAL FAST so in making a 5 gallon 25 liter batch you might lose half of it if you let it be exposed to air


hope that helps and if its clear as mud dont worry thats modeling 4 U


Balsaeater