hi all,
this may be a really dumb question but here goes.

can a two stroke engine fire up without a glow-driver as the engine is still hot. as it seems my thunder tiger likes to be re primed before it comes to life.and i value my fingers.
also i get a bit of dark oil moving from the muffler into the fuel tank contaminating the fuel tank when run at full throttle.

what am i doing wrong


many thanks plastercine

a new pilot who values the experienced pilots comments and tips

I am not 100% sure, but seems to me like you're trying to run it while it's hot and the burned oil is being pushed thru the pressure line into the tank. I don't mean to be rude or anyting, but the idea of startig with no glow driver is outta this world. The engine stays hot, but the glow plug has to be burning red to start.
Victor

Oh I'm sorry, I misunderstood. You are just worried that re-priming the engine it will backfire, NO, absolutely not, It will not back fire, you can flip it over without worries. But you may need a starter to start the engine. I had a 46 pro and it didn't start without starter if it was hot. Anyways, you can prime it with confidence.
Victor

Technically, yes, it is possible for an engine to start without the glow driver attached, but it is very unlikely. You can find whole threads in many different forums dedicated to just this questions and get 1000 different viewpoints of whether or not it can happen and there are stories of it happening. I know somebody who it happened to so I know its possible. A good way to view your engines and never have to worry about it is... always treat it as if it could start. When you prime it, hold one blade firmly with your WHOLE hand and turn it over like that, you dont have to "flip" the prop with your fingers to get it primed, simply turning it through the compression stroke a few times with your hand is fine, you can see it suck fuel into the line and carb as you do it. If you are holding the prop firmly and turn it over even after its primed, with the ignitor on you can feel the engine "kick" with a light bump as you go past the compression and the fuel in the cylinder ignites. Also, you mention the fact that you value your fingers... get a chicken stick or electric starter or thick leather glove. If you do choose to prime it by "flipping" the prop as if trying to start it, do it with a chicken stick or an electric starter anyways as many of the nylon/composite props available these days are razor sharp and even turning it over slowly with one finger can and will slice you... even the little ones.

Hope this helps,
Brian

Yes Plastrecine a 2 stroker will definately start when hot. I have done this a few times myself. Just be careful of the sharp prop edges. I know, believe me I know. The brown coming out may be unburnt castor oil. Check to see if your fuel has castor in it. If a little comes out this is normal. If a pile comes out check to see if you are runing rich. I hope this clears up your questions.

Mark Shuman

Ask anyone who owned a big supertiger when they first came out. We heard a few stories of hot no glow driver starts on cowled engines. I always had respect for any hot engine specially big tigers and gas on ignition.

jds

Definitely YES! Engine doesn't have to be really hot, either. A glow plug ignites fuel two ways: because the element is glowing red, and the catalytic action of the platinum element will ignite the mixture if conditions are perfect....JIM

Um, I dont mean to be rude, but thats pretty ridiculous. Igniting an engine without glow driver? Get out!!

It's true.

The combustion process is not a result of heat like in a car engine. It is a result of a chemical reaction between the alcohol in the fuel, and the platinum in the glow plug's coil. Heat simply assists the reaction.

So while it is unlikely, it is DEFINATELY possible for a warm engine to start without a glow driver attached.

Also go ask your full size aircraft cousin to go over to that hot Lycoming or Continental and swing the prop with the ingnition off. Or for that mater just stand next to the prop. Watch their eyes get big as they quickly tackle you before you get there. Continental and Lycoming tell you that in their manuals .......dont stand near a hot engine.

All it takes is to get whacked one time by a big Tiger and you'll be a turned into a believer.

LOL
jds

Although I have never seen it happen in over 28 years of flying, I know a few people that have had it happen. I would have never believed it, but almost anything is possible. The way I have always done it is when you flip it, flip it as if you had a glow lighter on it and you will be fine. Always treat it as if it were going to start.

I have seen an engine start just by adding the glow igniter, I have never seen one just start on its own. You need pressure and heat to ignite the fuel mixture. While you may have the pressure, I don't think you will have the heat needed to ignite the fuel. I would think you are safe!

It's absolutely possible.

The higher compression engines (like Super Tiger) do it more often, most sport engines with lower compression will have a hard time doing it, but it is possible.

(engines built for US use and the typical 5-15% nitro fuel have a lower compression ratio than those built for Europe and places where 0% fuel is more the norm).

Minn is right on, it's the methenol reacting with the platnum wire in the glow plug that keeps an engine running after the glow starter is removed, it can certainly start that way when warm.

Sorry but I also replied to a thread a week ago about Pt in glow plug but did not hear back.

the thjread was
http://www.rcuniverse.com/forum/m_13...tm.htm#1303078

I doubt that Pt is used in glow plugs, can you guys give me a reference where it says Pt is used in the glow plug.
Pt active catalsyts are used in methanol oxidation but doubt that Pt is used in the glow plug and also doubt that even it is a catalytic reaction taking place with the glow plug.

Here ya go:

http://www2.towerhobbies.com/cgi-bin...?&I=LXG899&P=7

How about a reference on Mecoa's web page:
http://www.mecoa.com/faq/glowplug/glowplug.html

If you don't like Mecoa, maybe you'll believe OS:
http://www.osengines.com/faq/faq-q663.html


That took about 5min to find a reference to Platnum being used in a glow plug coil. I'm sure that if you actually went to some pages with real tech info on their plugs you'd get even more info.

Let me ask you this, if the plug isn't creating a catalytic reaction, then how does the engine stay running after the battery is taken off?

You can measure the compression of the engine to determine that it isn't high enough to be a pure diesel engine. Methanol would take way more pressure to fire off than typical diesel fuel, and putting a diesel head on a glow engine rasies the compression quite a bit. Putting glow fuel in a diesel engine doesn't work.

Thanks Montague,

I looked at those pages and they helped, now I learned.

I looked O.S. Faq for this but serached for glow plug so I missed in fuel.

Thanks for the info.

Now I don't have the doubt and learned.

Umm..... If you read more abot full-size aircraft, you will know that their engines have this things called magnetos. They send signals to the spark plugs when the prop is flipped. That's why and engine may splutter if you move it......
Victor

By all means an engine can start without a driver attached. It has happened to me twice on my k&b .61. The engine was cooled between flights when I flipped it over before starting to make sure there was no fuel in the engine from siphoning. Can imagine the feeling one gets when something like that happens when you least expect it. It Can Happen And Does.

With any strong engine, I'm in the habit of holding the prop firmly before attaching the glow plug clip. Spontaneous fireups do happen.

well we arent talking about full scale planes.. and we dont have magnetos.. and yes an engine WILL and CAN start while hot.. i had both things happen.. put the glo driver on and the freaking thing started.. how.. i have no idea.. and not to long ago i started my motor back up after a full tank of fuel flight, with just my starter. so believe what you want, upgraded my respect for these things after that.

I know that this is a very OLD topic, but it really bears restating CORRECTLY!

Platinum, iridium and rhodium are all members of what are called the platinum group of metals; each of them are effective in initiating chemical reactions, either alone or in combination (alloys).

Platinum alone is best but is usually alloyed with one of the others for mechanical reasons (strength, durability), and for COST!.

YES, A HOT ENGINE CAN MOST CERTAINLY START WITHOUT A VOLTAGE BEING APPLIED TO THE GLOW PLUG: most every modeler of my age has seen a hot early model Fox .35 start this way. those early, sand cast jobs had a much higher compression ratio than the later models, 8.0:1 vs. 5.25:1 for the more recent ones, and were very prone to such behavior.

Sorry to be so blunt, but any other opinion is just foolish jawflap: there's democracy, to be sure, just don't ever lose sight of the important thing which is - what is, IS!, regardless of what we might wish for, or wish things to be.

I don't imagine that anyone will ever pay attention to this, but it really needed to be said, once and for all time.

Dear Lord: thank you for allowing me to be an engineer...

Morty.

To summarize, there seems to be some consensus that a warm engine can be started without applying the glow plug heater. Therefore, it pays to be careful flipping or turning the prop on a warm engine. OK, that makes sense to me.

Now, how many other than combatpigg think an engine can start by just putting on the glow plug heater (i.e. without flipping or turning the prop)? I suppose the theory is that there is some unburnt fuel in the combustion chamber that ignites when you put the glow plug heater on, starting the engine. This strikes me as so unlikely as not to be worth worrying about. If it could happen to a warm engine, why not a cold engine that's been primed? But what do you think?

The Cox .049 instructions used to mention starting a hot engine without using glow. (as if they were ever easy to start WITH the glow plug lit up...)

With high nitro (really high) you can start a COLD engine without glow! I've done it.

I have an MVVS 40 in a SIG Midstar 40. It also has a tuned muffler. So I set it a little richer than normal on the ground. As the engine comes on the pipe it leans out some. This is normal for a piped engine. It is also a high compression engine. I am also running 10% fuel without problems I might add.

It will occasionally just load up and stop while taxiing. I just go out and carefully flip it over. It usually just fires back up. I clear it out, taxie and fly it. Done it a number of times.

Mark Shuman

My friend had a Cox .049 on a CL plane and it would NEVER start no matter what we did. It even had a Spring Starter!