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Model J3-200 THERMO-JET

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Model J3-200 THERMO-JET

Unread postAuthor: DR » Sun Feb 15, 2009 4:49 pm

The Thermo-Jet Model J3-200 is a valveless pulse jet engine. It contains no rotating or vibrating parts. Basic parts of the engine include:

    (1) - Combustion Chamber
    (1) - Exhaust Tube
    (2) - Air Inlet Tubes
    (2) - Fuel Nozzles

The engine operates on propane fuel Forward movement of the Thermo-Jet is caused by a series of pressure pulses in the (Combustion Chamber), exhausting from the tailpipe (Exhaust Tube) and (Air Inlet Tubes), thereby producing thrust. Length and diameter of the engine determine the frequency of the pressure pulses.

Propane fuel flows through the fuel nozzles at high velocity, into the Air Inlet Tubes, forcing the surrounding air to also enter the air inlets and mix with the fuel with a ratio of approximately 15:1

    <a href="http://i44.tinypic.com/15p26c7.jpg"><img src="http://i44.tinypic.com/15p26c7_th.jpg"></a>

Fuel and air flow into the Combustion Chamber, where it is ignited by heat remaining from the previous combustion. Burned and expanded gas of combustion exhausts out of the tailpipe and air inlets at high velocity,
thus creating a low-pressure in the combustion chamber. This drop in pressure (below atmospheric) permits a new charge of fuel and air to flow into the combustion chamber, the process continuing at a frequency of approximately 240 - 250 times per second.

** "THERMO-JET Installation and Operation Model J3-200"

... Imagine a 4-Stroke Internal Combustion Engine (like the one in your Honda Civic), running at close to 30,000 rpm. :shock:

This is the one that my wife purchased from eBay, much to my dismay, at first. - I had been wanting to purchase a better-constructed one off of another site... The same site that denounces the one that we purchased, as a spot-welded piece-of-crap.

Well, for a "spot-welded piece-of-crap" , this thing was really nice-looking!
it came with the fuel system and some decent instructions and spec.'s
I'm happy with it, and had it running (late last night) at a steady flowing 50psig from my regulator.

<a href="http://i44.tinypic.com/292455f.jpg"><img src="http://i44.tinypic.com/292455f_th.jpg"></a> <a href="http://i39.tinypic.com/24ni5gj.jpg"><img src="http://i39.tinypic.com/24ni5gj_th.jpg"></a> <a href="http://i40.tinypic.com/k03vch.jpg"><img src="http://i40.tinypic.com/k03vch_th.jpg"></a> <a href="http://i42.tinypic.com/2s78e4j.jpg"><img src="http://i42.tinypic.com/2s78e4j_th.jpg"></a> <a href="http://i42.tinypic.com/25k65hv.jpg"><img src="http://i42.tinypic.com/25k65hv_th.jpg"></a> <a href="http://i44.tinypic.com/14mfmtc.jpg"><img src="http://i44.tinypic.com/14mfmtc_th.jpg"></a>

Long shot of it running at different pressures, idling and views into the Combustion Chamber and Air Inlet Tubes, as it's running:

<a href="http://www.youtube.com/watch?v=SepUzu07Ww0">YouTube Model J3 200 Thermojet 4:41</a>

At approximately 3:50 - 4:06 in the video, I try to capture a shot of the pressure gauge on the regulator. - The engine was "idling" at less than 5psig! - Pretty impressive for a supposed "spot-welded piece-of-crap".

4:19 - 4:27 shows the inside of the combustion chamber, as the engine idles.


    Type..............................................Reverse-Flow Valveless Pulse Jet
    Weight.................................................13 ounces
    O.D. - (Combustion Chamber)................3 inches
    Overall Length.......................................21 inches
    Thrust (in excess of:)........................3 pounds
    Specific Fuel Consumption........................5.5 LBS / HR. / LB. THRUST
    Frequency (approximately)...................240-250 Combustions Per Second
    Ignition...............................................NO Spark Plug required - (small propane torch will supply heat for ignition)
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Last edited by DR on Sun Feb 15, 2009 5:04 pm, edited 2 times in total.
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Unread postAuthor: jrrdw » Sun Feb 15, 2009 4:55 pm

I wish I had a high speed internet connection! Also, a wife like yours to buy me cool toys. Lucky you! :P
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Unread postAuthor: starman » Sun Feb 15, 2009 5:35 pm

Looks a lot like your homemade one...runs about the same too.

At least you have a quick way to heat up your garage this time of year!
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Unread postAuthor: psycix » Mon Feb 16, 2009 12:23 pm

It may be a spot welded piece of crap, but there are not many men who get a pulsejet from their wife.
What does such a thing cost?
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Unread postAuthor: jimmy101 » Mon Feb 16, 2009 12:56 pm

Pretty slick.

How long do you think the steel will last at full power?
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Unread postAuthor: SEAKING9006 » Mon Feb 16, 2009 1:51 pm

Cool, man. Check and see if a common IR receiver will pick up the exhaust from that thing. Then, pick up a couple PIC-14M's and build yourself a heat seeking missile. Been looking into building a system using an IR floodlight as an anti-aircraft system for airsoft/paintball where UAVs are in use, and the missiles lock onto the reflected IR light. Missiles will just have a cheap CO2 shotgun-type thing in the front. (Use an EDF instead of rocket motor; maneuvering parts on a rocket is illegal.)
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