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Wednesday, March 16, 2011

Running a PAW .06 on Home Made Diesel Fuel


The Number One Problem with Diesels:- 


The first big drawback with diesels is the lack of a ready source for commercial model diesel fuel, in North America. It is virtually impossible to find Commercial Model Diesel Fuel for running our Diesel Model Airplane Engines.



MAKE YOUR OWN MODEL DIESEL FUEL- THIS BOOK SHOWS YOU HOW.







The Solution:- One solution to this problem is to make your own fuel.


I found that common, easily obtainable items like; scented lamp oil, castor oil and cold weather Quick Start (ether), when combined in approximate proportions (60% 20% 20% respectively), will make a acceptable, alternate source for model diesel fuel.
I have since found, that these three ingredients will work very well in combinations up to equal parts, of 1/3, 1/3, and 1/3.


Proof that it works:- You can see one of my engines running on the 60%, 20%, 20% mixture by clicking here.


Ether is a nasty substance:-  Ether is highly volatile and will change state from a liquid to a gas at room temperature and for that reason it is difficult to pour; it is dangerous especially in closed spaces it could even be deadly. If that wasn't enough disadvantages, it isn't available in many countries for general comsumption. For all those reasons it would be a real advantage if one could run their engines without relying on such a nasty substance. A quick look at the reference table shows that there are few if any safe candidates with a auto ignition temperature as low as Diethyl ether. 


Not Real Diesels:-  Model diesels are not real diesels in the true sense of the word, as they do not have injectors to as do modern diesels. The injectors are designed and adjusted to inject vaporized fuel into the cylinder at precisely the right time in the cycle. Near the top of the compression stroke (when the compressed air exceeds the auto ignition temperature of the fuel). The model diesels on the other hand are generally 2 stroke engines that intake a fuel air mixture, compress that mixture on the upstroke and when the temperature of compressed mixture reaches the ignition temperature of the constituent with the lowest auto ignition temperature, combustion occurs which usually is the either. Either has an auto ignition temperature of only 160 degrees C as can be seen in the table below. Number one fuel oil with an ignition temperature of 210 degrees C, looks like it would be a good candidate for replacing the lamp oil in my mixture. It may even work well without any ether.



Zero Ether Experiment:- An experiment was conducted using a set-up using a PAW .06 engine and various kerosene based fuel mixtures. The experiment showed that the same performance can be achieved with a zero ether fuel mixture if the cylinder temperature is increased high enough to ignite the kerosene in the fuel mixture. The cylinder temperature is increased to this level by increasing the compression ratio and adding a high viscosity synthetic oil to improve the compression leakage rate. I have even resorted to using a pocket torch to help this heating process along. 
 .    


This picture is captured from a video clip of a PAW 06 diesel running on a fuel mixture with zero percent Ether. 

Watch a short video clip which demonstrates the techniques used to achieve those results.


video

The techniques demonstrated in this video can be used to make almost any diesel engine run. Even the infamous Gotham Deezil will run with a 80% Ether 20% high viscosity motor oil (see Gotham Deezil page).

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Auto-Ignition Data:- The Auto-Ignition Temperature - or the minimum temperature required to ignite a gas or vapor in air without a spark or flame being present - are indicated for some common fuels below:
Fuel or ChemicalTemperature
(oC)(oF)
Acetaldehyde175347
Acetone465869
Acetylene305581
Anthracite - glow point6001112
Benzene5601040
Bituminous coal - glow point454850
Butane420788
Carbon7001292
Carbon - bi sulfide149300
Carbon monoxide6091128
Charcoal349660
Coal-tar oil5801076
Coke7001292
Cyclohexane245473
Diethyl ether160320
Ethane515859
Ethylene490914
Ehtyl Alcohol365689
Fuel Oil No.1210410
Fuel Oil No.2256494
Fuel Oil No.4262505
Heavy hydrocarbons7501382
Hydrogen500932
Gas oil336637
Gasoline280536
Gun Cotton221430
Kerosene295563
Isobutane462864
Isobutene465869
Isooctane447837
Isopentane420788
Isopropyl Alcohol399750
Light gas6001112
Light hydrocarbons6501202
Lignite - glow point526979
Methane (Natural Gas)5801076
Methyl Alcohol385725
Naphtha5501022
Neoheaxane425797
Neopentane450842
Nitro-glycerine254490
n-Butane405761
n-Heptane215419
n-Hexane225437
n-Octane220428
n-Pentane260500
n-Pentene298569
Oak Wood - dry482900
Peat227440
Petroleum400752
Pine Wood - dry427800
Phosphorous, amorphous260500
Phosphorous, transparent49120
Production gas7501382
Propane480842
Propylene458856
p-Xylene530986
Rifle Powder288550
Toluene530849
Semi anthracite coal400752
Semi bituminous coal - glow point527980
Styrene490914
Sulphur243470
Wood300572
Xylene463867
The flammable (explosive) range is the range of a gas or vapor concentration that will burn or explode if an ignition source is introduced. Limiting concentrations are commonly called the lower explosive or flammable limit (LEL/LFL) and the upper explosive or flammable limit (UEL/UFL).
Below the explosive or flammable limit the mixture is too lean to burn. Above the upper explosive or flammable limit the mixture is too rich to burn. The Auto-Ignition Temperature is not the same as Flash Point - The Flash Point indicates how easy a chemical may burn

Credit The Engineering ToolBox site.


All this Information and Much More in The Diesel Fuel Book