Fuel for winter flying (Full Version)

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ablais007 -> Fuel for winter flying (2/1/2005 7:45:33 PM)

I live up in Canada.. The great white North.... I have tried flying my Cub with a Saito 65. this winter. For the first flight things go well but as the fuel gets colder the engine does not want to stay running.... If I wait and try to start it after the fuel cools down in the field box, it will NOT start at all. I think the glow plug can not stay lit with the cold fuel. I am using 15% Nitro and 18% oil..
Any suggestions out there? I had heard from someone that you can add some gasoline to the glow fuel for easier starts. Or maybe a hotter glow plug?

Any suggestions appreciated.

Thanks.



RCPAUL -> RE: Fuel for winter flying (2/1/2005 7:50:54 PM)

Always use a hot (4-stroke) plug in a 4-stroke engine - any time of year. Also, a propane torch can be used to heat the cylinder before trying to start it. Can you also keep the fuel in the car to keep it warm? I used to fly in New England in the winter off of skis - cold hands were more of a problem for me.

Hope this helps.

Paul



MUNGAM -> RE: Fuel for winter flying (3/4/2005 12:32:24 AM)

This is what I've learned from flying in the Vermont winters:

1) Use only 100% synthetic oil in your fuel. Caster oil turns to a grease in the cold and will prevent the barrel in your carburetor from rotating. In other words , you have to fly the plane out of fuel.
2) If possible , keep your plane in a warm spot between flights. I fly my small stuff in the winter and stick it in the back on my van with the heater running when not flying. It is also a good spot to warm up those hands.
3) I have not done this one but I was told a thermos of warm water poured over the head will aid in starting.
4) One fellow who had problems with his engine quieting in flight wrapped aluminum foil around his head decreasing the cooling efficiency of the fins on the engine. It worked like a charm.
5) Try not to use ABC engined in the winter. The cylinder will contract more in the colder weather causing the excess piston wear . One of the guys I fly with has an ABC engine that will only run well in the winter now due to this. Try to use ringed engines.
6) Use small plane that you don't have to take apart to fit in the car.



sopwith -> RE: Fuel for winter flying (4/9/2006 3:40:39 AM)

I live in Colorado and have flown in -5F, even that is too cold on the hands. I make my own fuel with 5% acetone and have no trouble starting most engines. I have a flying shed where I keep my planes and fuel, with no electricity or heating. Some engines I wrap the head only with electrical tape and a tie wrap to keep it on, and it keeps it hot and prevents dead sticks. You cannot use caster oil as it can't handle the cold and settles to the bottle bottom.



RaceCity -> RE: Fuel for winter flying (4/9/2006 5:38:09 AM)

and I put little mittens on my propeller.......

Carbs freezing up in flight from castor? Castor settling out of the fuel right before your eyes? ABCs shouldn't be run in winter? Where DID you guys read this?

Pouring a thermos of hot water on the engine is a personal favorite. I'll have to remember that one. <GGGGG>

(for a real thrill...pour a thermos of cold water on a real hot engine)

It's all nonsense. Wives tales, and stories told around a campfire. Pure and simple.

Glow engines don't start well in winter because the alcohol fuel simply can't create enough ignitable vapor, unless the engine is primed substantially more than would be required in the warmer months. Same thing used to happen in Dad's '65 Chevy in the winter. Had to pump that gas pedal like mad and hope she'd fire before the battery croaked. Your glow engine is no less affected. Increased nitro content in the fuel can aid in cold weather starting.

Additionally, "Ronsonol Lighter Fluid" which is naptha based, will readily vaporize and aid in starting in even the nastiest cold weather.
Remember Pops shooting some starting fluid in the carb? That worked because vapor burns far better than pools of liquid fuel in an engine.













XJet -> RE: Fuel for winter flying (4/9/2006 5:50:36 AM)

RaceCity has nailed it.

Alcohol (methanol) requires heat to vaporize and in winter, there's far less heat around :-)

You might have noticed (if you live in a humid area) that when you run your Saito in summer, you get condensation forming on the intake tube. This is because the vaporization of the methanol as it travels up the intake tube is sucking the heat out of that metal -- so it gets cold. So cold in fact, that the moisture in the air condenses on it.

It is this vaporization-induced lowering of temperature that causes carburetor icing in aircraft and which requires them to have manifold heating when operated in certain conditions.

If there's insufficient heat around then very little of the methanol will actually vaporize before it hits the combustion chamber. This is important because, believe it or not, liquids do not burn (combust).

Only the vapors released by liquids burn and in order to release those vapors, the liquid has to be at or above a certain temperature. This is why you can drop a lighted match into a bucket of kerosene (Jet A1) and all it does is go out -- there's no bang, no ignition, nothing. At ambient temperatures, a puddle of Jet A1 doesn't release sufficient vapor to support combustion. In fact, to get it to burn, Jet A1 has to be broken up into tiny droplets (with lots of surface area) and/or heated.

So, to get your engine started and keep it running, you have to either use some other fuel component that *will* vaporize at the prevailing ambient temperature, or ensure that your engine is warm enough to allow the methanol to vaporize.

One solution (as pointed out by others) is to add small amounts of a more volatile liquid such as acetone or lighter-fluid. Another (as others have pointed out) is to pre-heat your engine using hot water.

Looking on the bright side, your engine should produce more power when fed with tje colder, denser air of winter :-)



loughbd -> RE: Fuel for winter flying (4/10/2006 6:37:38 AM)

You all missed the obvious. Use a higher nitromethane content fuel. However, we all flew in the nasty cold winter when I was in japan and everyone used 5% nitro fuel. Made starting a bummer because no one used electric starters. Learned a little trick early on. Always took a large thermos full of REALLY hot coffee with us. Poured a bit on the head just before we started the engine. Started right up. Then a bit in us to keep us going. Once the engine was going it stayed going. The only trouble was getting them started. That and freezing to death.



sopwith -> RE: Fuel for winter flying (4/16/2006 3:33:33 AM)

Non sense, old wives tales, stories around the campfire, where did you read this....I didn't read it, I do it. When was the last time you flew in sub zero weather in North Carolina? Caster oil will come out of solution in cold weather especially when there is any water in the fuel. It will literally settle to the bottom of the fuel tank and clog up the engine with cold sticky oil. Cold weather requires a synthetic oil, not caster oil if you want reliability. I don't have heat in my flying shed and whatever the air temperature is, determines the fuel temperature. I have run engines in the -10F range with no problems with synthetic oil. Methanol has a flash point of about 56 degrees F, Acetone is sub zero, which is why it helps starting in cold weather. Letting the engine heat up for a few minutes with the glow heater and a towel wrapped around the head also helps.



RaceCity -> RE: Fuel for winter flying (4/16/2006 4:11:30 AM)

We don't get a lot of mega-cold weather here in NC, but I didn't start flying here. I began my RC ventures in Northern Michigan where it does "occasionally" get damned cold. Our fuel was 50% castor and we never had all the grief you do.

In Northern New Hampshire (another less-than-tropical locale on occasion) we never had problems either.

Nor in Upstate NY....the occasional cold day occurs...

So don't feel you're going to educate me on cold weather flying......I have a little experience in the cold in the past 30yrs of r/c flying.

If you have problems in the cold...it's not your castor.

But thanks for your comments culled from weeks and weeks of experience nonetheless.






loughbd -> RE: Fuel for winter flying (4/16/2006 4:21:28 AM)

I fly straight castor oil fuel. I leave it in my garage all winter. I fly in the winter. I live in Washington and it gets cold in the winter. My fuel never gives me any trouble in the winter. The oil does not settle out ot get the little white flakes in it in the winter. I DO NOT USE synthetic oil in ANY of my engines. I do not have trouble with my engines. My bearings NEVER rust.



loughbd -> RE: Fuel for winter flying (4/16/2006 4:26:32 AM)

I just put a 1/2 pint of 100% castor oil 10% nitro fuel in my freezer. I'll tell you tomorrow what it did. The only time I ever saw castor come out of solution was really old fuel and the oil went rancid. Had nothing to do with temperature. nOh by the way, it gets damn cold in some places in North carolina.



ablais007 -> RE: Fuel for winter flying (4/16/2006 2:52:32 PM)

I have heard many good things about castor oil vs. synthetic. Winter starting is something I never related it too.

Thanks for the information all!



loughbd -> RE: Fuel for winter flying (4/17/2006 5:16:52 AM)

Well so much for that cold weather myth. I just got that 1/2 pint of fuel out of the freezer. 24 hours at 0 degrees F. Kenmore Freezer, Hobby Shack brand fuel. White Lightning, 10% nitromethane, 20% castor oil. NO synthetic. The fuel is clear as water. Looks just like a glass of pale pee. Zero oil out of suspension, no white flakes, no nothing. Just clear pale yellow fuel. Just like it looked before I put it in the freezer. I always experiment before I make claims on a forum like this.

A couple hours at the field in the cold isn't going to have any effect on fuel and a few minutes in a fuel tank isn't going to either. No one flies in 0 degree weather but it makes a good story. A lot of guys fly in the snow using skiis or floats and they don't have problems with fuel either.

If you don't believe me try it yourself.



wcmorrison -> RE: Fuel for winter flying (4/17/2006 4:55:52 PM)


quote:

ORIGINAL: XJet
You might have noticed (if you live in a humid area) that when you run your Saito in summer, you get condensation forming on the intake tube. This is because the vaporization of the methanol as it travels up the intake tube is sucking the heat out of that metal -- so it gets cold. So cold in fact, that the moisture in the air condenses on it.


Hey, XJet, I got condensation in Arizona at 30 humidity in my 4C intake. The reason is the pressure drop from the barrel to the intake valve. Basic air conditioning, the carb is a simple expansion valve. Better known in the recip flying world as "carb icing." Perhaps the alcohol aggrivates it a bit but it is not the fuel vaporization that causes the condensation.

Cheers,

Chip



Sport_Pilot -> RE: Fuel for winter flying (4/17/2006 5:42:24 PM)

What you say is true about the carb being a basic expansion valve. But the air does not go into a phase change. The gas in the full scale plane and to a lesser extent the alcohol in our engines do go through a phase change, thus the drop in temp.

Look at this in a way that high school and many college teachers don't seem to teach. If you compress air it gets hot, that is because the molecules are closer together and bounce around more, thus heat. If you suck the air out then they opposite is true, they are further apart and generate less heat. But with a phase change they go from very compact to very widely spaced and unless heat is asorbed they will condensate, but since their is an initial temp drop then heat is asorbed and this causes it to cool.



loughbd -> RE: Fuel for winter flying (4/17/2006 7:09:05 PM)

Bill, you guys are talking about the exact same thing. Liquid freon expands and vaporizes taking heat out of the surrounding area. Liquid methanol vaporizes and takes heat out of the surrounding area. It's called Latent heat of vaporization and that's why airconditioning works. The only difference is we don't compress the methanol back into a liguid so it gives off the latent heat. That's how heat pumps work. In A/C the freon is compressed into a liguid in the compressor. It then goes to the evaporator in the car, expands and vaporizes and youi get cold because the freon absorbed the heat. Now the hot freon goes to the condensor in the engine compartment and gives off some of the heat it absorbed then back to the compressor to get turned back into a liguid giving off more heat.



loughbd -> RE: Fuel for winter flying (4/17/2006 7:18:13 PM)

It's not the air we're talking about, it's the alcohol. Compressing air does not cause a phase change. It is a completely different thing. It WOULD change phase if you compressed it enough and drew the heat off as you did it. That's how they make liquid air, Oxygen and any other liquified gas except CO2 which sublimates. Compressing air to it's liquid state is exactly how airconditioning works. Gives off it's heat as it changes to a liquid, absorbs heat as it changes back to a gas. Same with freon but it's a different refrigerant than air. Ammonia was one of the first refrigerants. You need a refrigerant that changes phase at a reasonable temp and pressure. That's why F12 worked so well.

Oh, I did teach junior High science.



Sport_Pilot -> RE: Fuel for winter flying (4/25/2006 2:58:53 PM)

Loughbd,
I said it was the fuel's phase change. I was trying to explain how decompressing will cause the temperature to drop. A phase change is simply a more extreme example of decompresion, as the molecules are even further dispersed. There are all air, air conditioning systems which do not use a phase change. They are used in aircraft.



loughbd -> RE: Fuel for winter flying (4/25/2006 8:24:13 PM)

That may be but that's not what's happening in the intake of an engine. The alcohol evaporates, that absorbs the heat of vaporization and that lowers the temp. Same thing happens when you sweat.



Sport_Pilot -> RE: Fuel for winter flying (4/26/2006 3:38:55 AM)

If you read the first paragraph in post 15, I explained the phase change of our fuel.

Water is an excellent refridgerant.



loughbd -> RE: Fuel for winter flying (4/26/2006 5:28:06 AM)

Actually, if water was an EXCELLENT refrigerant it would be used in AC/R systems and save the ozone hole. As it isn't it isn't used as a refrigerant. Nasty Chlorofluorocarbons or Ammonia are.

It's the evaporation of the alcohol in our fuel that causes the cooling in the intake pipe of an engine. Just like sweat. Works exactly on the same principal. That's WHY we sweat. Water on our skin evaporates and cools us off. The alcohol in the pipe evaporates absorbing the latent heat of vaporization (35.21kJ/mol) from the surounding material which removes that amount of heat from the surounding material causing it to cool. The moisture in the air around it gives OFF it latent heat of voporization to the cool pipe and condenses on the outside of the pipe.

I spent too many years working with the Auxillary Division on a submarine to not know how the R-12, R-11, R-113, and R-114 plants work.

You can say all you want but that's how it works.



Sport_Pilot -> RE: Fuel for winter flying (4/26/2006 2:24:46 PM)

quote:

Actually, if water was an EXCELLENT refrigerant it would be used in AC/R systems and save the ozone hole. As it isn't it isn't used as a refrigerant. Nasty Chlorofluorocarbons or Ammonia are.


R718 (H2O) is an excellent refrigerant (well maybe only a good refrigerant), it is used in absorption chillers, they usually use waste heat and lithium bromide as an absorbent. The cycle is to heat the water / bromide solution to about 10 to 15 Psig, the water evaporates leaving a stronger solution behind, the vapor is condensed, then it is pumped to the low pressure side where it evaporates at about 5 microns Hg pressure, it is used to chill water at 42 to 45 degrees, some the remaining vapor is then passed over a spray of the strong bromide solution. The bromide solution and the pumps pumping out the solution are enough to keep the pressure low, if non condensables are kept out of the system.

It is generally not used for anything but waste heat, because absorption systems are not very efficient due to excess heat, however some compression water systems have been built.



loughbd -> RE: Fuel for winter flying (4/26/2006 5:15:59 PM)

Bet they don't work worth a darn below 32 degrees either which makes it a LOUSY refrigerant for freezers. Also must be bulky as heck. Also very restricted use. So... not a good refrigerant. A refrigerant yes, but one of VERY limited use. For that matter just about anything can be a refrigerant



loughbd -> RE: Fuel for winter flying (4/26/2006 5:29:01 PM)

Wasn't this thread about fuel for winter use??



Hobbsy -> RE: Fuel for winter flying (4/27/2006 8:39:22 PM)

This thread is totally Off Topic and closed.



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