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Additve to glow fuel to increase energy density?

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Additve to glow fuel to increase energy density?

Old 11-25-2003, 10:16 AM
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jdbrownwv
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Default Additve to glow fuel to increase energy density?

Hi,
Does anybody know of any additive that can be added to glow (methanol) fuel to increase its energy density. I'm looking to get more run time out of my engine without converting it to diesel. I won't need high rpms either. I have a powered glider and want to keep it up a long time, so I'm planning a high pitch prop, low rpms combination. If I could add something like kerosene, or something that has a higher energy density but wouldn't effect the glow operation with the methanol. Anybody done this, or know of the percentage additions and the performance ramifications,

Thanks
Doug Brown
Old 11-25-2003, 11:39 AM
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Default RE: Additve to glow fuel to increase energy density?

I think you can add some gas to the fuel. Not sure how much you can add before you have problems. You probably can increase the amount you can add by using a colder plug.
Old 11-25-2003, 12:10 PM
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Default RE: Additve to glow fuel to increase energy density?

Several years ago a guy who worked at Hobby-Lobby recommended adding 8oz of gasoline to the gallon of fuel to run in Mercos. There was absolutely no change in the way they ran.
Old 11-25-2003, 12:37 PM
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Jim Thomerson
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Default RE: Additve to glow fuel to increase energy density?

Try running your engine on diesel fuel. If you can make it work, you will get greatly increased fuel economy. I've run K&B 4011's on Davis 1/2A diesel fuel a couple of times. The RPM was the same as with glow fuel (11 x5 prop, CL venturi), but the needle went in 1 1/2 turns. I tried two different engines. One ran fine after leaving the glow plug hooked up for maybe 30 sec. The other would undercompress when I disconnected the glow plug. I havn't checked, but I think the second engine has an extra head gasket.

Jim
Old 11-25-2003, 12:46 PM
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Default RE: Additve to glow fuel to increase energy density?

It would be a rare engine that would have the right compression pressure to run as a Diesel. I tried it with my Saito .80 and it would run on it but I could not go beyond half throttle. It started to make Black and Gold Grenade noises.
Old 11-25-2003, 01:50 PM
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Default RE: Additve to glow fuel to increase energy density?

Did it do any damage to the Saito 80? I sure do like the idea of a Saito Diesel...

Maybe 1/2 FAI and 1/2 diesel would do better? I wonder if "Proof" has anything to do with Methanol. In early days alcohol would burn at 100 proof or 50%. I wonder if methanol is the same way with 50% being somewhat magical, or does the glow plug somehow change this? Maybe assuming FAI with 20% castor (80% methanol) mixed with something such as gas/diesel/kerosene such that the ratio was 63% FAI and 37% other would work without needing additional glow heat. 63% FAI * 80% methanol = 50% methanol by volume).

Doug
Old 11-25-2003, 05:09 PM
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Jim Thomerson
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Default RE: Additve to glow fuel to increase energy density?

Wasn't it that 100 proof alcohol would burn when mixed with gunpowder? Some of the South African CL stunt flyers routinely run diesel fuel in a variety of glow engines. They are flying at 6000 feet and say that they get more power. Either the 1950 or '51 Aeromodeller annual reports fuel consumption tests on a number of 2.5 cc diesels. They also tried two glow engines on diesel fuel. These had the best fuel consumption results, better than any of the diesels.

Jim
Old 11-25-2003, 09:50 PM
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Default RE: Additve to glow fuel to increase energy density?

Jim is right about the South African flyers. The trick seems to be in getting the engine to start (using the glow plug for ignition at first) and become hot enough to continue running on straight diesel fuel (model type, not auto). Without any methanol the plug is going to go out as soon as the battery is disconnected and it then becomes a true compression ignition engine. Even a normal diesel needs to have its compression backed off as it warms up or it'll be overcompressed.

However, because the original poster doesn't want to convert his engine to a diesel and use their special fuel then there's probably not much point going along these lines. In the old days of CL Team Racing, petrol was added to the fuel to get extra range from the lower fuel consumption. I think it was somewhere around 10% but in that case it was a juggling act between long range and max power for speed so where power isn't a necessity it could be worthwhile trying a higher % of petrol. I wouldn't smoke around it though
Old 12-01-2003, 10:05 AM
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Default RE: Additve to glow fuel to increase energy density?

Ok,
- I tried a 20cc CoolPower FAI run and got 2:47 @ 12.8K
- I then tried a 20cc (90% CoolPower FAI, 10% gas) run and got 4:15 @ 12.5K
- I also tried a 20cc (90% CoolPower FAI, 10% K-1 kerosene) run, but the kerosene didn't seem to mix with the glow fuel. I will try mixing gas/kerosene and adding this to the glow. Kerosene has an advantage in that it acts more like a lubricant than gas.

The 10% gas addition seemed to give me a 50% increase in run time and seemed to run the same as glow fueled only. My concern is that the CoolPower FAI didn't give the green oil residue any more, it was a dark brown/ black residue on the exhaust. I think that my synthetic oil was burning in the process. I'm thinking of adding castor to the glow, and 2 cycle oil mix to the gas to help protect the engine. Are there any suggestions to the gas/oil ratio in the mix? I was thinking of a 25:1 gas mix for the gas portion bud didn't know if it would be enough oil of an ABC engine. This is a Magnum XL-15A BB ABC engine.

When I get the gas/oil ratio straightened out, I will try to run higher gas concentrations to obtain a smooth running glow engine with extended run times.

Thanks for you help and suggestions
Doug
Old 12-01-2003, 09:12 PM
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Default RE: Additve to glow fuel to increase energy density?

Coolpower "FAI" is a 17% all synthetic which is a marginal oil content anyway. Adding the 10% gas cuts the oil content down to about 15.5% (although that's slightly made up for because gas lubricates a little). But by getting the much longer run time from your Coolpower/gas blend you're considerably cutting down the flow of oil through the engine which will make it run hotter so I think you're right that the exhaust residue shows the oil is being burnt. What I'd suggest is going to a fuel with at least 20% oil and half of that being castor. Forget about the normal 2 stroke oil, it won't mix with the methanol.

It's good to see someone experimenting and posting the results
Old 12-22-2003, 03:44 PM
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Default RE: Additve to glow <span class=

It was no problem to get a quart of castor from a nearby hobby shop and add a few ounces to my fuel. Perhaps you can do the same. However, IMHO, the best way to make a powered glider stay up is to catch a thermal. After a while it stops making that awful noise, too. But I'm kinda surprised the engine will run with gas. That's interesting and I may keep it in mind. Will the gas attack the silicone fuel tubing?

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