Oh No Not another Fuel Mix Question!

there are calculators for this very thing , By the time you get the castor mix right your nitro will bee very low , will run but makes starting and needle sitting a pain and want stay . If you can get nitromethane to bump the content up to at least 25% would bee helpful , take a look at this >  http://web2.murraystate.edu/andy.batts/ps/fuel.htm   And here is another >> http://www.nitrorc.com/fuelws/ At the bottom of the page or read all  

Redback do this.
https://www.htdirect.com.au/products/redback-sport-car-fuel-30-nitro-1-lt-rfsprt301?variant=38021233180832&currency=AUD&utm_medium=product_sync&utm_source=google&utm_content=sag_organic&utm_campaign=sag_organic&gclid=EAIaIQobChMI8vvwz7PX9wIVVVZgCh1zcA9tEAQYAiABEgLRdfD_BwE

With 30% nitro you will have more than enough left to feed to your Cox engines once you add the castor.  Also, in my opinion, if you add another 10% of castor to bring your oil content up to 25% total, that's more than enough castor, in fact, it may end up being too much. 22% oil total will still have 7% castor, which I thinks would still offer enough protection to a Cox.  There are some on this forum who claim to use very low castor content oils in Coxs with no ill effect.

If you need to make use of your 5 litres or 10% Nitro Redback, you're going to have to find some nitro as well as the castor to make it work in a Cox.  They will run on 10% nitro, but not very well.

https://rcfuelsupplies.com.au/index.php

Thanks for your answers. They were very helpful.
I did not know that fuel specific calculators existed but they do and are a blessing.
Mixing fuel is quite a science and silly things like making sure I get the right size vessels to do the end mix crosses my mind otherwise I will look a bit stupid if it all starts flowing over coz the vessel is too small.
Fuel storage vessels are another bone of contention as nobody makes tin cans any more with screw tops.
I will enjoy looking around trying to source them.

https://www.houseofcans.com/metal-containers/screw-cap-cans

Wholesale but you can ask them where to buy one or two cans

Levent Suberk wrote:https://www.houseofcans.com/metal-containers/screw-cap-cans

Wholesale but you can ask them where to buy one or two cans

Thank you...Brilliant but the cost of having them sent from USA to Australia would be expensive.

Woody,
Get creative. How far away is your closest drinking establishment? Or, as we call them in the USA, a bar. Ask the proprietor for cast-off bottles with caps...vodka, whiskey, rum...anything. They can be used to mix and store your fuel. I have cut plastic milk jug bottles to make new seals for bottle caps like that.
Even plastic rubbing alcohol bottles can be used for the same purposes.

The Andy Batts calculator above is used for mixing two fuels in quarts, that is 32 ounces. I reverse-engineered it for myself so that I mix eight ounces at a time. My measuring cup is actually a drink mixer 2 ounce cup in 1/4 ounce graduations. So, I simply use two ounces of my "high test" plus two ounces of my "high test" mixed with 2 ounces of my "low test plus 1.5 ounces of my low test, and add 1/2 ounce of castor. I would mix as larger measures if my measuring cup were bigger.

Use your 10% N fuel as one of the fuels, and your 100% methanol as the second fuel.  Practice with it BEFORE actually blending your resultant fuel.
Don't worry about the difference between imperial vs metric...just consider the ratios themselves. As an example, I would substitute each imperial ounce and mix using 10 ml in place of each ounce...such that you would have a final mix of 320 ml, or just less than a standard 375 ml bottle of booze (if that is a standard bottle where you are). Or mix as each ounce is commonly roughly 30 ml...then your blended lot would be just under a full liter.

Since you know your fuel is 15% oil, but don't know the ratio of synthetic to castor, just call it 7.5%/7.5% in the calculator. Even if you call it 100% synthetic, you'll see the castor content would be high enough to protect a Cox engine. Check out the calculator with some trial runs. I think it will work for you.

Since you will be low on the nitro,.you may find the engine may run best with a thinner head gasket, or even without the head gasket.

OldEngineRod's fuel company link also shows Nitromethane by the liter...lucky you guys!

Play with that fuel calculator to see what happens with the second fuel as 75% methanol and 25% nitro...

944_Jim wrote:OldEngineRod's fuel company link also shows Nitromethane by the liter...lucky you guys!

Play with that fuel calculator to see what happens with the second fuel as 75% methanol and 25% nitro...

The good thing about that calculator is that because it uses percentages, you can use Millilitres in place of ounces and it still works.

Somewhere, can't recall exactly but I think was Peter Chinn, to not use an oil content above 25% because the metering passages on the Cox engines were small. I found out I was able to run my Babe Bee on such a mix, mainly intended for my legacy larger CL engines, such as the Testors .35 Red Head and Enyas. (Yes, I know that with Enyas you can get by with 20% oil, even states in their engine manuals.)

My Enyas ran fine, but my Norvel's wouldn't run reliably.

Regarding the 10% nitro, this is more or less the absolute minimum as half A aircraft in general (except for the need-for-speed crowd) are slightly underpowered to begin with. A Q-Tee will poke along quite well as it has very generous wing area, flies on its wings.

Back in the 1970's I sometimes subsisted on lower nitro content fuel, because the local shops didn't have the higher nitro stuff stocked. As they say in motorcycles, "The worst ride is better than the best day of work." I found it no different with model planes.

Also, the "nitro" rules of thumb (for the lack of a better word) aren't quite what they seem. Think about it. You add a touch more oil. In order to maintain stochiometric for proper combustion of methanol requires opening the needle a touch more, so you can bring the fuel side of the equation up, giving the same amount of nitro as before. So, by adding 10% Castor oil to make for a 25% oil package with 15% synth you basically retain the same amount of nitro.

Now, say a Golden Bee operating a couple hundred RPM lower be a detriment on a sport plane? Just depends on what target one is shooting for.

So, the little gems of wisdom put out by @OldEngineRod who lives near you, Woody, might be your best source of fuel stocks down under.

Thank you so much all of you. I really appreciate all of your help.
I will keep re reading all your answers.
It is starting to make sense to me now.
So....this arvo we took a trip to the model shop and I am glad I did.
Bought 5Litres of 100% Nitromethane!!! Yeah!!!!
They also discovered some old stock that they never knew they had of SOLARFILM and LITESPAN.
I cleared them out on all their Litespan and bought 12 rolls of assorted colours of Solarfilm really cheap.
Went to a store and bought Four fuel cannisters. Three of plastic and a nice 2Litre
Round tin brand new.
So now I have 10 litres of 10% nitro, 75% methanol mixed fuel.
5 Litres of 100% nitromethane.
1 litre of castor oil.
1 litre Klotz KL200
various measuring jugs....
AND A PART RI IDGE IN A PAIR TREE!!!
All this to make a pint of potent Cox fuel.
Love it though.
So now I am on a new journey that of making fuel mixes.
I only did it once before when I made up some Diesel.
Oh that Ether and Kerosene!!! The flowers Man!!!!
Thought you would appreciate a little pic of Woody's Fuel works.

When I doctor up the buggy fuel that I buy, I just use that calculator to get me to 25% nitro, 25% total oil. Always seems to run better than if I mix my own from scratch at 25% nitro & 25% full castor. The synth in the pre-mix seems to help stabilize things a little.

I notice that you have some measuring scales in your picture. The figures that we all throw around are generally by fluid volume, not by weight. You just need a graduated measuring jug and you're set.

Thanks for mentioning that.
I was wondering.
I will scout around for appropriate measuring jugs.

Hi woody, dont know where you are` in Oz, but in South Oz, Scotcher Race Fuels sells everything you need except the mixing jug. http://www.scotcherracefuels.com.au/ I used to buy my race fuels from them when I was younger and raced yamaha TZ GP bikes, then for race fuel when I raced speedway, and now I buy Methanol, Nitro, and pure Castor oil from them. This is where most of the South Oz raceing people get their fuels. Castor oil comes as 5L minimum and in a container. Nitro can be bought in 1litre containers or 200 litre if you need. Lol. Methanol comes out the pump. They can supply containers, but I have my own steel 5 litre and 10 litre containers. they also sell empty 1 litre containers suitable for Nitro fuel.

Mixing is really easy, buy an engraved glass measure jug from coles or woolies. Measure 250 mills of Castor and pour into 1 liter container, measure 250 mils of nitro into and pour into container, measure 500 mills of methanol and pour into container. Now you have 1 litre of 25x25x50 % nitro, castor, methanol, fuel for you model engine. The prices are significantly cheaper that the hobby stores and the fuels etc. are turned over quickly as its a main source of drag race, speedway etc. fuels in south Oz. Mixing it, wont even take 15 minutes. It just couldnt be simpler. I would expect if you search you will find other race fuel distributors on Oz.

Yabby

I strongly recommend storing all of your ingredients in air/liquid tight containers. The fuel jugs for petrol/diesel aren't air/liquid tight to any significant degree. I wouldn't carry my fuel in them for any flying. My own fuel jug is a six ounce flask. My mixing jug is a one quart old school heavy brown glass medicine bottle. If/when I go fly the big stuff, I have a one quart fuel jug for that.

Most of the top-shelf guys DO advocate measure by weight. I'm not top-shelf by any stretch, so I'm completely satisfied using fluid measure.

Synthetic oil is good and aids keeping the castor build-up down. Castor is required for the piston ball-joints. So as long as I keep at around half and half synthetic to castor, I'm comfortable with that.

If I were to tilt it either way by any significance, then I'd be mixing for particular engines. More castor for my older technology engines, more synthetic for my newer engines.

OS, Norvels, AP .061s, and a couple of OS knock-offs are lumped together as newer engines. Enyas, Fox and Cox (and one un-tested Testors 0.40 throttled engine) are my older engines.

I consider 2/3 synth to /1/3 castor a fair mix for the newer stuff, and then flip flop for the older ones...and those are the extreme limits, not targets for me.

I generally just try for half and half for both sets. Then, with respect to total oil content, I shoot for around 20% all around, but I'll go heavier (up to 25%) for the really old stuff, and wouldn't cry about getting down around 15% as a minimum for the newer ones. Again, a few points either way haven't broken anything yet. Maybe I need to run the stuff more to the point of failure.

With respect to nitro, I try to keep around 20% all around. I'll take my regular brew and de-tune it down closer to 10% for the Fox. But I need to watch that one carefully as I have only a few quarts of bench time with it.

I also don't feel like a few percentage points are going to make enough of a difference in the Roundie-Roundie patterns I fly. None of my engines have suffered for it.

total SCORE on the LiteSpan. one of my favorites. really good stuff for thems of us that fly small planes