Alternative to glow 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
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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.

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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 -- The Big-8 hierarchies (comp, humanities, misc, news, rec, sci, soc, talk) are under new management. See http://www.big-8.org for details.
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Martin X. Moleski, SJ wrote:

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.

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snipped-for-privacy@digiverse.net wrote:

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.
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Robbie and Laura Reynolds wrote:

I gather in the war they ran cars on it.
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snipped-for-privacy@digiverse.net wrote:

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.
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Robbie and Laura Reynolds wrote:

I meant to say "tricky". I wasn't trying to sound cool.
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On Thu, 26 Oct 2006 22:15:19 -0500, I said, "Pick a card, any card"

Leave the tricks to me, mate. http://www.rayhaddad.com That's my day job. -- Ray
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Ray Haddad wrote:

Now if you came up with a trick that turns a heap of balsa back into a model, then you'd be really cool ;-)

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On 27 Oct 2006 01:38:15 -0700, I said, "Pick a card, any card" and snipped-for-privacy@digiverse.net instead replied:

It's always a LOT heavier when I do that. -- Ray
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Robbie and Laura Reynolds wrote:

Thinking about it, there are quite a few LPG vehicles around right now, in GB: http://tinyurl.com/yxzshw It sure would be a lot easier to get hold of for modellers, though one downside (and upside: no clunk) is a pressurised tank and potential leaks. I can imagine quite a few mishaps with stored models leaking gas.
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snipped-for-privacy@digiverse.net wrote:

Couldn't you use a soda bottle? They hold lots of pressure. If you could come up with a decent regulator in a small size, you'd have your problem half solved.
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Folks have used soda bottles as reservoirs for retracts.
I've seen pix of planes torn apart when the bottles failed.
If someone goes down that road, they sould probably reinforce the bottle with a layer or two of fiberglass, depending on the nature of their design and their target pressures.
Overfilling happens. People should anticipate human mstikaes and (within the limits set by aerodynamics) built for some worst-case scenarios.
                Marty -- The Big-8 hierarchies (comp, humanities, misc, news, rec, sci, soc, talk) are under new management. See http://www.big-8.org for details.
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Robbie and Laura Reynolds wrote:

Still abit complicated though, I would have to add oil somehow.
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snipped-for-privacy@digiverse.net wrote:

You'd have to add oil, and you would have to come up with a way to vary the amount of gas for throttling as well as attach it to the engine intake. Seems like you could use a needle valve to get the oil right into the intake stream easily enough.
This project is starting to sound like something that would require about a year of experimenting in a well-appointed shop. If I wasn't trying to start an amplifier company I might do it myself.
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Robbie and Laura Reynolds wrote:

I think it would be simpler to just get a spark conversion kit for glow engines, like these: http://www.westonuk.co.uk/index_205.htm http://www.nelsonhobby.com/prospark.html
Actually, since I do have a machine shop and a bit of electronics savvy, I could just make a batch of them for all the glows I want to use.
It would be easier if someone happens to already know of a DIY circuit diagram for an ignition circuit. I could program PIC processors etc but why re-invent the wheel.
Or I could just vandalise the latest cheap Ryobi PLT - 2543Y 25cc strimmer: "Powerful, 25cc 2-stroke Line Trimmer with diaphragm carburettor for effective working at any angle. Maintenance-free electronic ignition."
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I've converted several of the 18 and 25 cc Featherlite leaf blower engines and they work wonderfully.Vibration is not bad but yuo can soft mount the engine and get it even lower. I've had nothing but good results with the Featherlite engines and they are dirt cheap.
snipped-for-privacy@digiverse.net wrote:

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AV8R wrote:

They are not available in europe.

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I'm going to suggest diesel if you like wet fuel or electric if you don't. I've had nothing but praise for my MVVS diesels! The fuel is easy to make and cheap and plenty of formulas are on the web to make your own. If the diesel fuel is a problem, I'm going to suggest gasoline. I've been able to hush them up pretty well! I suppose what you are flying makes a difference as to your power requirements.
Try a diesel. I think you will be happy. Plus, diesel packs far far more BTU than glow fuel or gasoline so you get by with a smaller tank, etc.
snipped-for-privacy@digiverse.net wrote:

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