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COX FUEL ?????

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Help! COX FUEL ?????

Post  MANDALAY Tue Sep 24, 2024 4:41 am

Is this blend ok for Cox engines 0.049 . 0.074 , 0.09 ?

15 % Synthetic
5 % Castor oil
20 % Nitro
60% Methanol
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Help! Re: COX FUEL ?????

Post  944_Jim Tue Sep 24, 2024 5:21 am

Mandalay,
Look at the left edge of the webpage...down low. You are looking for INFO. Inside of INFO is the original file blend sheets for Cox fuels.

My preference is 1/2&1/2 castor synth and 25% nitro. My wallet's preference is closer to 22% N, only because I buy 33% N truggy fuel (high synth, no castor), and adding castor and a bit of methanol to get 1/2&1/2 at 18-20% usually cuts the N down to just under 22%. This is just a function of blending a hotter fuel containing lots of synthetic oil to create a more castor-oriented blend.

Some suggest fuel MUST be blended based on mass (weight). I suggest getting castor is very important...and Cox engines run on anything from 15%-35% N quite satisfactorily. Just look at the original blends. I even ran my childhood Cox engines on Testors 10% fuel in a pinch. In short...mine may not be the perfect blend every time. But it has enough nitro to needle well and enough castor to protect the piston ball joint. I will caveat that with I fly alone, not in contests, so in the air is more fun than holding the plane making "Reoowww, Reoowww" noises. I'm only competing with the obstacles (life) to having a flying morning or afternoon. At that point any nitro is better than no nitro, and smelling burning fuel is cheaper therapy than an hour with a shrink.

I will also suggest mixing in small lots. It is easier to burn up several ounces of a blah blend as you dial in what you like. More N makes for faster burn rate, faster fly rate, sooner dizzies. Less N makes for sedate flying at a slower burn rate, and less dizzies. Of course, hair on fire is exciting...smashing a plane isn't. Remember, this is supposed to be fun!

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Help! Re: COX FUEL ?????

Post  MANDALAY Wed Sep 25, 2024 4:23 am

Many thanks for the heads up.

I looked at the formulas. They range in Nitro 10% > 15% > 30% with the percentage of methanol reduced by the increase in Nitro. The other items Caster oil and synthetic being the same.

I am Industrial Chemist so making my own blend is very easy. I can get all the individual items so I can blend them myself.

The synthetic is Koltz KL200 ( KL 201 doesnt exist )

I looked up all the specific gravities of the components and they do have the same values as noted in the cox formulas.

I prefer to do by weight so much easier and cleaner.

With that I can blend any ratio I wish.

Which ratio would you recommend ?
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Help! Re: COX FUEL ?????

Post  MANDALAY Wed Sep 25, 2024 4:55 am

Note the Cox formulas are Percentage by volume

The 30% formula actually is 36.49% by weight


               LITERS % BY VOLUME       S.G                 KGS         % BY WEIGHT
METHANOL 455..........50................0.7955.............361.9525.......42.86
CASTOR     164..........18................0.9635.............158.014.........18.71
NITRO       273...........30................1.129...............308.217.........36.49
ADDITIVE   18............2..................0.9095.............16.371...........1.94
                 910..........100.................................... 844.5545........100.00

NOTE GALLONS OR LITERS DOESNT MATTER as it is just a unit.


In you method are you using volume or weight as the percentage ?

I have read companies using 50/50 blend castor / synthetic
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Help! Re: COX FUEL ?????

Post  GallopingGhostler Wed Sep 25, 2024 5:25 am

Thanks for each component, quantifying the equivalent weight for the historic Cox volumes,  @MANDALAY.

My Two Cents on the matter. Matter of opinion, but I'thinking that for a manufacturer with automated equipment may have had an easier time basing his amounts on weight rather than volume. This just conjecture. I've never seen such equipment in person, so others who may be more intimate may be able to contribute more accurate information.

Earlier in my career in aerospace modifying system software for load servo controlling and data acquisition on aircraft structural airframe testing, then later on implementing building automation systems on energy systems (HVAC) on facilities, am familiar with flow, weight, distance, force and strain measurement under computer control.

Here, I modified a gallon of Morgans Wildcat 15% nitro fuel for use with my C/L cross scavenged engines (Testors McCoy .35 Red Head, etc.) which was also good fuel for running my Cox half-A reedies, OK Cubs, Testor/Wen-Macs, etc.

COX FUEL  ????? 2018-021

The 25% oil mix is max recommended for Coxes because of its small fuel metering passages. I think it was Peter Chinn who commented that in one of his engine articles archived on Spectre Flight Model Engine Tests. There are a few enthusiasts that recommend none other than 29% all Castor fuel for the legacy engines, particularly old Fox Stunt .35's. Accordingly, such fuel would not be good for Coxes. (There seems to be as much controversy over oils in model airplane fuels as there are with motorcycles oils in discussion groups.)

https://web.archive.org/web/20081008144111/http://www.spagthorpe.com/maintenance/synthetic.html

Spagthorpe Maintenance Bulletins - The Dangers of Synthetic Motor Oil:

My Norvel .061 Big Mig ran, but was a little fickle on the 25% oil mix, harder to get a good consistent run. I guess the fuel metering passages is what made it baulk. It is Schneurle and my guess is uses slightly smaller fuel passages.

Being a sport flyer versus competition, I never had to have cutting edge, so if I had a good flight, it was good enough for me.
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Help! Re: COX FUEL ?????

Post  Ken Cook Wed Sep 25, 2024 2:11 pm

Most of my fuel is 50/50. Sig Champion was my fuel choice for over 20 years. Sig used Klotz in a 50/50 blend 10% castor/ 10% klotz. I also run full Klotz synthetic and I do it in vintage engines despite the naysayers indicating it will ruin engines. I've never ruined a engine running full synthetic fuel which included the purposeful intention of trying to destroy a Cox engine. I use nothing but Klotz products and never tried any other manufacturer of oil. Most of the time when I mix my Cox fuel, I use KL-100 castor/synth blend of Klotz. When I run out of this, I mix Klotz Benol and full synthetic Techniplate.

This is where things can get problematic, Klotz had to putz around with their product names. Klotz in the past offered KL-100, KL-200. Now its a mixture of whatever names sounds pleasing. They have original Techniplate, Super Techniplate and a myriad of others. One was full synthetic, the other being 80% synthetic with a 20% mix of castor. You have to read the description. My reasoning for using Klotz products are due to the way they mix with alcohol. I've experienced problems in trying to up the oil content of pre-mixed fuels. I've seen the oil separate and also float on top like vinegar and oil salad dressing.

I no longer doctor any fuel for a one very main reason which I mentioned above. The other is that companies like Morgan fuels WILL NOT disclose how they mix nor will they offer true contents. I've gone back and forth with them over the years on e-mails and the same answer always is in the end that the ingredients and contents used are trade properties which they will not disclose. I buy my stunt fuel and I've been mixing all other blends for a few years. The most difficult to obtain is the nitro which is over $100 a gallon delivered to my door. My main supplier which I used is no longer selling small quantities of nitro which is a bit disturbing. They will sell 5 gallons vs 1 gallon. For most, this is out of reach due to cost and or necessity to use it all.

The last speed shop of my area closed in the fall of 2022. Just prior to it's closing, I was purchasing methanol for under $5 a gallon. Now that gallon is over $20. I inquired about purchasing nitro which they wouldn't sell me at the time. If I didn't have a vehicle for it to go immediately into, they were not by law allowed to offer me nitro as a raw product. I could buy nitro which was preblended with alcohol which is VP's 50-50. This product is still available and it's also a more economical approach to making fuel. 5 gallons is under $200. This will require a bit more math but certainly worth the effort. My son and I use approx 7-8 gallons of stunt fuel in one year. VP Powermaster fuel is what I normally purchased which was the situation up to last year. The price skyrocketed so high it was not practical. I used to pay $24 for a gallon which is now $54 which doesn't include shipping. I typically buy 6 gallon cases.
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Help! Re: COX FUEL ?????

Post  cstatman Wed Sep 25, 2024 6:47 pm

Sig's web site claims they have 25% Champion available again - but no 30% yet.
it was my fave for long time
https://sigmfg.com/collections/fuel/products/sig-champion-fuel

I have been buying Brodak 1/2A lately
https://brodak.com/fuel/fuel/fuel-qt-15-nitro-11-5-castor-11-5-synthetic-2.html
because its easy - log on to web page, buy, pay, receive in mail


All the speed shops in San Jose have closed or no longer sell fuel.
the 3 gas stations that USED to sell race gas at the pump have converted those tanks to Diesel
ordering VP is $$$$ in California

so no more mixing. I get it, the future is coming, and it has no gas for no body
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Help! Re: COX FUEL ?????

Post  Cox International Thu Sep 26, 2024 9:00 pm

Companies like Morgan fuels WILL NOT disclose how they mix nor will they offer true contents. I've gone back and forth with them over the years on e-mails and the same answer always is in the end that the ingredients and contents used are trade properties which they will not disclose.

Which is pure BS, as any competent outfit can analyze the exact content.

To add fuel to the flames (pun intended), here is a link to our fuel calculator, for those buying fuel with synthetic oil only and wishing to add castor oil:

https://coxengines.ca/public/files/castor.xls

As well as a link to our fuel guide:

https://coxengines.ca/public/files/FG.pdf
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Help! My fuel for Bee's, Dee''s, Widows, Thimble Drome's Sure Starts, service, etc...

Post  1975 control line guy Mon Sep 30, 2024 5:29 pm

I have an eclectic collection of engines that I have been bench running and flying since early this year. I have settled in on a mix of 100 ml of VP pro car 30%/ w/ 9% oil with 10 ml of Green Health pure caster oil. Both can be easily had in the USA. So far nothing has broke or seized and my starts and running have been consistant. Flushing fuel tanks and lines with denatured alcohol and application of after run oil I think contributes too.
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Help! Re: COX FUEL ?????

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