Glow plug can start pulsejet?

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sedalc
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Glow plug can start pulsejet?

Post by sedalc » Fri May 06, 2011 10:26 pm

Hello

A glow plug can start burning a pulsejet? Diesel glow plug is heated to over 1000°C in 5s and the point of self ignition of the gas is much lower (I intend to use butane or propane).
This is a relatively small pulsejet.

Thanks.

larry cottrill
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Re: Glow plug can start pulsejet?

Post by larry cottrill » Mon May 09, 2011 2:29 am

sedalc,

I for one would love to see you make this work. However, it is doubtful.

In my early days, I tried glow plugs (small model airplane types) with petrol, alcohols and ethyl ether. I never got a single bang. Not one, not under any conditions. Here's the reason (I think): Glow plugs work well in engines with fairly high compression (diesels, 2-stroke engines on alcohol). The platinum heating element reacts especially to alcohol vapor UNDER PRESSURE. In any pulsejet, you'll never get more than 2:1 compression ratio, and MUCH LESS at startup time. I think that's the whole problem.

This is also why spark plugs should have a very wide gap -- you don't need a "hot" spark, you need a long spark that arcs through a LOT of vapor molecules (due to very low gas density). At least, that's always been my theory. Others are welcome to disagree, if they feel so inclined.

L Cottrill

sedalc
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Re: Glow plug can start pulsejet?

Post by sedalc » Thu May 12, 2011 4:38 pm


metiz
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Re: Glow plug can start pulsejet?

Post by metiz » Thu May 12, 2011 4:48 pm

A flyback ignition, although probably very effective, can also be extremely dangerous. You are likely going to touch the engine during starting (through air gun, injectors or similar). I don't know much about electricity so I don't know for sure, but if the full load of that flyback goes through your body you won't be happy at all, you could even die. be carefull
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sedalc
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Re: Glow plug can start pulsejet?

Post by sedalc » Fri May 13, 2011 6:46 pm

This flyback isn't dangerous. This is a plasma bowl flyback ( not tv ). It is powered by a 12v 1A transformer.

A neon sign transformer and microwave transformer are lethal by this montage is inoffensive.

Rocket Man
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Re: Glow plug can start pulsejet?

Post by Rocket Man » Sat May 14, 2011 12:35 pm

1968 I had a small hobby pulse jet engine smaller than the Dyna Jet Engine it used a model airplane glow plug to get it started. It had a place on the nose of the engine to connect a model airplane fuel line to a model airplane fuel tank. The engine ran on model airplane fuel. The engine came with a piston that was used to start the engine. The piston was on a long stiff wire, you slide the piston all the way up into the exhaust pipe of of the engine then pull the piston out of the engine as fast as you can to make it start. When the piston was pulled out very fast it forced air/fuel to be sucked in through the intake. On a cold day the engine was hard to start but on a warm day it would start in the first pull. This was a small pulse jet engine the compustion chamber was about 1 1/4" diameter the exhaust tail pipe was about 3/4" inch.

Mark
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Re: Glow plug can start pulsejet?

Post by Mark » Sun Mar 25, 2018 1:29 am

Rocket Man wrote:
Sat May 14, 2011 12:35 pm
1968 I had a small hobby pulse jet engine smaller than the Dyna Jet Engine it used a model airplane glow plug to get it started. It had a place on the nose of the engine to connect a model airplane fuel line to a model airplane fuel tank. The engine ran on model airplane fuel. The engine came with a piston that was used to start the engine. The piston was on a long stiff wire, you slide the piston all the way up into the exhaust pipe of of the engine then pull the piston out of the engine as fast as you can to make it start. When the piston was pulled out very fast it forced air/fuel to be sucked in through the intake. On a cold day the engine was hard to start but on a warm day it would start in the first pull. This was a small pulse jet engine the compustion chamber was about 1 1/4" diameter the exhaust tail pipe was about 3/4" inch.


That sounds like a neat way to start a pulse jet. I would've liked to have seen that. Was it an American design or foreign?
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