Alternative to glow fuel

On 26 Oct 2006 06:12:25 -0700, snipped-for-privacy@digiverse.net wrote in :

Maynard Hill flew a 5 kg plane (WET) across the Atlantic on a naptha-based fuel.

Dunno how it would work in a higher-revving, hotter application.

I suspect other alcohols don't pack as much punch as methanol.

All you have to do is mix some up and see what happens. :o)

Marty

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Methanol IS alcohol. I suspect that methanol was chosen for its' particular boiling point/ability to vaporize and its' flash point. You can experiment with other alcohols or just go with larger planes and gasoline power. I know you will be able to get good 'ol petrol there.

Jim

I assume you're going to stay there for a while, I have several suggestions:

1. Ethanol was suggested elsewhere -- this would be an interesting experiment, and the platinum glow plug should still catalyze it -- although possibly not enough. I'd also try acetone, which may be more available but will eat more plastics than methanol or ethanol.

1. Diesel. Assuming you can get your hands on ether, check out Davis Diesel Developments for conversion kits. The engines smell different and many find it objectionable (I don't). You generally get better performance for the engine size once you get the adjustments sorted out.

2. Gas. I've seen conversion kits for two-stroke glow engines to gas. I don't know how this would work on an ABC engine, but apparently it works well in iron-steel engines.

1. Swap meet. Sell you engines for as much as you can get, and use the money to buy electric.

2. Can you really not get methanol and castor oil? Methanol is a pretty common industrial solvent; I would expect that if they do any resource extraction at all it's around.

5a. Since it's a part of Portugal ("The Azores are an autonomous region of the inept Portuguese Republic and as such it luckily has its own Political Administrative statute.") it's within the European union -- can't you just mail-order fuel?

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Conversion to other fuel bases isn't worth the effort in my estimation. Either sell them off and apply the money toward electric/gasoline motor/engines, or put them in storage and switch to electric or gasoline for flying.

Some of the new 26 and 40cc SPE conversions are inexpensive and are small enough to fly 1.20 - 1.40 glow power designed models with little to no conversion. Good luck.

Ed Cregger

On Thu, 26 Oct 2006 11:09:22 -0400, James Beck wrote in :

It is possible to convert some glow engines to gasoline.

You need a spark plug, an ignition system, a different carb, and (I imagine) some skill and luck. Our glow engines developed out of gasoline engines and some can, I think, be converted back.

You won't get the same power out of the converted engine. Sometimes I can understand the reason why not, and sometimes I can't. Ounce for ounce, there's more power in gasoline, but methanol behaves differently in combustion so that, somehow or other, it produces more power in two engines of the same displacement (more methanol has to be burned to get the power, but more methanol CAN be burned, so it all works out).

You might also be able to dieselize some of your glow engines. The ingredients for diesel fuel should be readily available (kerosene or naptha (?) and ether). Guys who like diesels love diesels. I've never tried one myself and I try to keep my distance from the diesel evangelists.

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Ether is becoming difficult to obtain in some parts of the world. Ether is a principal component of model Diesel fuel. Ether really stinks. The kerosene component of model Diesel fuel is good smelling when compared to the ether that is necessary for good running. Of course, this judgement is subjective.

The storage and handling of model Diesel fuel is a PITA and unless you are a passionate model Diesel devotee, that alone is enough to ward off most modelers.

Operating costs are similar to operating glow engines on a comparison basis of running time per unit of cost. While you don't gain anything monetarily, your model does carry a greatly reduced fuel load.

Having a variable compression capability does mean that you have a much wider latitude in propeller selection. Large props that would damage a glow engine if used are easily handled by a model Diesel engine because of the compression adjustments ability to alter the engine's ignition timing.

I was bitten by the Diesel bug as an adolescent. Once bitten, always infected.

Ed Cregger

Firstly, thanks for all the replies so far, folks.

Ed Cregger wrote:

I'm wondering if there is some way of using butane/propane and adding oil somehow? It's their main domestic fuel there.

Another thought was compressed air (!). I can get steel hydraulic tube certified to 300Bar (about 4000psi?). I have a 200bar stirrup pump for my precharged air rifle but usually people just fill diving cylinders for filling their rifles. Before anyone comments: Yes I am aware that crashing a small cylinder pressurised to 200Bar might have interesting results....! I have seen working free-flight planes using a plastic drinks bottle as the air reservoir, the engine was some small glow with a bicycle schraeder valve substituted at the top. Makes one think the same should be feasible with a much higher pressure supply and a bigger engine...

I can convert a strimmer/weedwacker or chainsaw engine for the camera plane. The Azores are pretty lush and everybody needs them so they are widely available. The main problem will be getting rid of vibration, as we hope to shoot broadcast quality.

I don't think I can get ethanol there but acetone is easy.

You mean normal diesel or the model diesel wich is even more difficult to get?

Ah! I'll look into that.

Already have some electric, but it can get windy there, so I want a bit more umphhh.

Not in the Azores.

Possibly, but if it has to come by ship rather than air it will take at least a month from Lisbon. I suppose I could plan ahead and order a lot of it.

wrote in

Hmmm... It might be simpler just to go big electric (for the smaller planes). The Azores are too.... kind of peaceful to inflict too much engine noise upon. If I go really big electric I could also film wales and dolphins without disturbing them much. Problem is there are quite a few territorial buzzards there, so I'll have to build manouverable....

Ah!

Don't think I can get ether there.....

On Thu, 26 Oct 2006 13:48:10 -0400, "Ed Cregger" wrote in :

Looks that way to me.

We've got one (1) Dieseler in the club. He seems to be having lots of fun. Also flies glow, so he's not too rigid about it.

Marty

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On 26 Oct 2006 11:23:28 -0700, snipped-for-privacy@digiverse.net wrote in :

There are tiny C02 indoor planes.

In principle, you could probably construct an air-driven engine of any size. Inject a little oil in the air stream and off you go.

You might be able to do the calculations to see how much air it would take to turn a .46-size engine at (say) 11,000 RPM for 8 minutes. Looks to me like it's all multiplication. Put a one way valve in the top to hold the pressure for compression, release it for the upstroke. Figure how many degrees the input valve had to be open for and rig a little cam of some sort.

My guess is that the weight of the bottle that can carry the pressure to drive that much air to turn a reasonable prop at a satisfactory RPM is going to be a LOT higher than a battery and an electric motor.

Marty

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Not necessarily, the air cylinder for my pcp rifle doesn't weigh much at all and can hold over 200 Bar of pressure. Incidentally, they make carbon fibre scuba tanks that can take 300 bar now. Any engine specifically adapted for compressed air doesn't need cooling fins either. The valve is simply operated by the piston by fitting it where the glow would go. The amount of air going in each stroke can be tuned by screwing the valve in or out and the throttle valve would be real simple too.

On 26 Oct 2006 11:32:39 -0700, I said, "Pick a card, any card" and snipped-for-privacy@digiverse.net instead replied:

That would have been my first option before I tried to mix any. Just get a 55 gal drum of the stuff and save a lot over the year or so it takes to use it up.

-- Ray

If they have an auto parts supplier in the Azores you may be able to get engine starting fluid, which is ether in a spray can.

The only model engines I know of that run on butane or propane are turbines.

Theoretically, you should be able to configure a small piston engine to run on compressed natural gas or propane. The question is whether you would be able to find a pressure regulator small enough to fit in the airplane. The regulators on the old butane powered tractors we used to run when I was a kid were rather large. Even if you could find or make a small enough pressure regulator you'd still have a lot of extra weight because in addition to that you would still have to carry an ignition system. It would be great to have the option if you were flying big slow models, though.

I gather in the war they ran cars on it.

For the price of a 55 gallon drum I might as well go electric and use the latest lithium batteries.

On 26 Oct 2006 16:54:32 -0700, I said, "Pick a card, any card" and snipped-for-privacy@digiverse.net instead replied:

The point is that shipping a drum is close in cost to shipping a box of 4 gallons. Check it out sometime. Ocean freight is dirt cheap. A drum of fuel that you use over time will turn your flights of fancy into a highly economical endeavor.

-- Ray

Probably so. It's not a particularly trick technology. You could look around and see if anybody has invented a micro gas regulator in the 60 years since it was popular to run equipment on propane.