On J230, the heat, and suitability of the Rotax 912ULS

[Bruce Tuncks]

I'm sure you are right PMC, its just that I never saw one. There used to be a drink called " white Lady", where you mixed the metho with milk. I guess the milk absorbed some of the poison.

Methyl alcohlol ( CH3OH) is what we ran glo-plug engines on. There is a little in natural ferments too, and it is what gives you a hangover, since a metabolic by-product of methyl alcohol is quite deadly.

[kiwiaviator]

1 hour ago, pmccarthy said:

Not just Aborigines, lots of white metho drinkers back then.

Yep. Very common sight in the Cross during the 80's

[facthunter]

methanol is called "wood alcohol' and is poisonous. In some suspect countries you may get in in bar drinks. Metho and boot polish was used by derelicts. The boot polish has nitrobenzene in it which has a very sweet taste counteracting the stuff in the metho some what. I wouldn't recommend it as it's a known carcinogen.

  I don't think alcohol ruins rubber. A mix of metho and castor oil was used in an emergency in older brake systems. Mineral oils will swell the rubbers in a short time. If you spill oil on your radiator rubber hoses remove it quickly. Glycol is a good rubber cleaner. The aromatics in 98 might be more of an issue. If there's mineral oil on your aircraft tyre for long, chuck it away. (The tyre , not the plane) It wouldn't be safe to use. Nev

Edited September 14, 2021 by facthunter

[skippydiesel]

On 20/08/2021 at 7:08 AM, Bruce Tuncks said:

Thanks Onetrack. The snow system claim that their thing only uses 160 ml of water per minute, so a couple of litres of water would be enough for any climbout.

I am always suspicious, of the efficacy, where the recommended quantities, do not take into account the variables for your system eg fuel additives that are by the tank (how large/small is your tank???)

[Bruce Tuncks]

Nev, while alcohol may not ruin rubber, it apparently attacks the sealant used in older Jabiru fuel tanks. There was a service bulletin to this effect.

I was also of the impression that it also attacked some rubber types, so it is good to know that this may not be true.

[facthunter]

The liner/sealant is another matter. Nearly all car and bike hydraulic brake systems use an oil from one maker and it's hygroscopic and lifts paint and doesn't stop rust. Citroen cars use a mineral type and so do some small aircraft. Those last two don't use any rubber in the system.. There's natural rubber and butyl rubber which you can't patch or vulcanise easily.

  I have had speedway bikes  the older ones use rubber piping satisfactorily as fuel feed (Methanol) but later ones have reinforced plastic which goes rock hard fairly quickly..Nev

[Bruce Tuncks]

On the subject of running motors from methanol, I can report that I once used it in a borrowed  lawnmower and for some reason the lawnmower went about twice the normal RPM. I had run out of petrol  with just a square meter to go, and I saw this can of model plane fuel and decided to try it out.

Well I successfully evaded the lawnmower owner for a week or so, but he finally caught up to say..." I dunno what you did but it has never run so good as when you returned it."

I may have given it a decoke, but to this day I can't work out why the governor allowed it to over-rev like it did.

[facthunter]

When you lean out a hot  two stroke on No LOAD it will rev  quite (EVEN VERY) high on nearly no throttle. They will also keep running with the ignition off or plug shorted out under these circumstances. NEV

[Bruce Tuncks]

You sure described what I saw Nev.  There was some primitive governor which consisted of a flap which closed the air off when centrifugal force exceeded a spring force. I would have thought that this would have worked regardless of what the fuel was, but it didn't.

[facthunter]

It's already running leaner on the alcohol. It requires a large increase in Jet sizes and often flow to the carb as well.. Nev

[Old Koreelah]

Today I finally got to install my water injector, which I hope will cool the heads during climbout on hot summer days, as well as decarbonising my combustion chambers. Made from a half-litre spray bottle (SWMBO had been using it while ironing my shirts) and a little fish tank air pump (total cost $14)

 

At full power, the throttle arm earths out the air pump, which pushes water out of the bottle.

The spray jet is mounted inside the air filter box and aims a fine mist into the airstream as it is sucked into the carbie.
 

Haven’t much control over the flow rate; a fine spray delivers only 50ml per minute, full squirt is about 160ml. I’ve dialed in a narrow spray of about 80ml/minute. 

My Jab 2.2 burns about 400ml per minute at full power. That’s a water/fuel ratio of 1:5.

 

An ex-Jumbo pilot tells me that on early 747s the flight engineer used water injection for extra boost and to keep the turbines from overheating. On takeoff it burned about a tonne of jetfuel and 1.8 tonnes of water.

That’s a pretty damp water/fuel ratio- far more than I would dare with a piston engine.

 

I presume one purpose of the methanol in the water is to prevent carb icing; Since my injection rate is so small, I might start off with pure water and see how that goes.  

 

If anyone knows the ideal water/fuel ratio for a pistone engine I’d be interested.

[Bruce Tuncks]

Good onyer old K . I agree with what you have done and will be keeping my fingers crossed that it works well.

Take-off and climbout seem so hard on a cooling system that I think it would be an obvious thing to do.... best wishes from Bruce.

Sorry but I have no idea of what the ideal fuel/water mix should be, but any improvement will help so the main thing will be to see what happens with a smaller amount like you are going to do.

[facthunter]

Check that water doesn't end up in the Carby bowl.  The principle is proven . You just have to rig it to work. It makes a LARGE difference to the power of the RR Dart 532 in the later F 27's.. If you have no better info try methanol/water at ratio 1:5. Nev

[Bruce Tuncks]

I reckon the methanol absorbs the water nicely and makes it less likely to go to the carby bowl and build up there like facthunter says to avoid.

 

[facthunter]

. Too much methanol will produce a rich mixture as you are not adding any oxygen to burn it, as you do  with Nitro. Both add gas mass. (more molecules to bounce around and up pressure)  and that ups power by giving extra torque.. Nev

[turboplanner]

1 hour ago, Bruce Tuncks said:

I reckon the methanol absorbs the water nicely and makes it less likely to go to the carby bowl and build up there like facthunter says to avoid.

 

You don't want methanol in the carby bowl either or the bowl and jets will be full of the waste from its reaction to whatever it can eat.

 

The injection should be downstream of the petrol jets so how would the water/methanol get back up into the bowl?

 

I'm curious about the reason for injecting methanol; if you want to use water injection to cool the head area, what is the purpose of the methanol, when you can just increase the richness of the petrol?

 

Very broadly to get the same result an engine needs about twice the volume of methanol than it does when running on petrol - so there's a major volume difference.

 

Methanol burns slower than petrol, so you have a burn conflict in the combustion chamber with non-burning junk in the way of the initial petrol flame.

 

In the car industry, water injection kits were available from speed shops a few decades ago, but they came and they went, so there wasn't really a consistent opinion on benefit.

 

I'm not saying methanol wouldn't work, but when I use it I have to reject the carb to 2x and advance the ignition, which take time to get right on engines where compession ratio has been increased.

 

 

 

 

 

 

 

 

 

 

 

 

 

[facthunter]

Water Meth has been used for 90 years now in aviation including turbo props. as well as high performance  pistons.

   100% methanol engines (speedway bikes)  don't run any extra advance  and have "fixed" advance even for starting by pulling the rear wheel and run too cold often.

  The Fokker F27 would hardly lift anything without water meth available. You even turned it on  pre landing  in case of  a go around or engine failure.. The water meth was near the gear lights and you got 5 FIVE greens. Nev 

  

[turboplanner]

LOL I’ll take you on for six laps then.

[facthunter]

Very cunning. You don't have enough fuel for 6 laps. 

 I'll tell you something though. The Shed smells beautiful for about 6 months after it's used.  Nev

Edited November 4, 2021 by facthunter

[turboplanner]

54 minutes ago, facthunter said:

Very cunning. You don't have enough fuel for 6 laps. 

 I'll tell you something though. The Shed smells beautiful for about 6 months after it's used.  Nev

You were right in terms of the bikes. When you buy the engine it's set for methanol and set to race, so no changes to timing.

[facthunter]

the "Thing" that allows you to start it seeing the CR is about 13/1 is starting it with the throttle closed and only the choke on (by pass type).   The cylinder doesn't fill.   You can do the same with an aero engine if you want to be kind to it.  Nev

[turboplanner]

5 minutes ago, facthunter said:

the "Thing" that allows you to start it seeing the CR is about 13/1 is starting it with the throttle closed and only the choke on (by pass type).   The cylinder doesn't fill.   You can do the same with an aero engine if you want to be kind to it.  Nev

Yes they're vicious pieces of work (the bikes) I've seen them started by people with the knack of an arm flick of the tyre. The riders are a different breed of people too. How they are not disembowelled by that open back tyre I'll never know.

[facthunter]

It's actually deceptively easy if you know what you are doing. Watch closely next time and you will notice the wheel being pushed right up to compression  backwards to take advantage of the flywheels and ensure the cylinder is not filled or you will tear your arm out of your shoulder socket. They'll tick over as steady as an M20 BSA. Same as if you are bump starting a single bike. Push back first and pull in  (disconnect)the  clutch as soon as it fires. Nev

[turboplanner]

You don't have to worry about plug gap with them. One guy was copmplaining about lack of spark on his Jawa; the lead was only throwing a half inch spark and he knew of someone in Queensland that made magnetos that REALLY threw a spark!.

 

[facthunter]

Magnetos have been a constant problem. Pulsing vibrations. The latest are low tension with a coil remote near the plug Since mid 60's  Nev