The Great Ramjet Challenge!!!

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Zippiot
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Post by Zippiot » Sat Jan 13, 2007 7:09 pm

I just drew the parts on sheet and am about to cut them out, if this jet works I'll make a pdf of the plans (its quite small) so it will be easier for others to build a working ramjet...hopefully this one makes thrust

I am going to try a new flameholder design, involves a big washer and a piece off a bike I found!!
Sailing Student- How do I know if my life jacket is tight enough?
Me- Can you breathe?
Sailing Student- Yes
Me- Then its too loose!

Zippiot
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Post by Zippiot » Sat Jan 13, 2007 9:05 pm

I love cutting wheels on a grinder!!!
Like butter doesnt even come close!!
Might even finish the thing today...hopefully i get all the parts right this time
Sailing Student- How do I know if my life jacket is tight enough?
Me- Can you breathe?
Sailing Student- Yes
Me- Then its too loose!

thecheat
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Post by thecheat » Sun Jan 14, 2007 2:47 am

Hey... just checking in for the first time in a while... I've been... distracted...

(I've been working on making an underwater tunnel gun with my laser pointer...)

Not much has been accomplished on mine... I've still to mount the diffuser and the reducer at the rear of the jet... the spike has been welded in place... boy this stainless is hard!

Zippiot, Cutting wheels are good! usually much easier than a hacksaw.

:wink:
Lasers, jets, and helicopters HURAH!

redneck
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Post by redneck » Mon Jan 15, 2007 8:40 am

i got my best run yet on you tube now. sorry it is the only way i can post vids as of right now.... the video is the one that is 4 min 33 secs long. it is running on liquid map gass, though it seems i aint getting enough air in my jet. any sugestions on a better blower, or a better air supply? id sure hate to have to start over again just cause my jet is too large.... also.... why come is this thread so dead as of late????????

http://www.youtube.com/watch?v=DWSpHsb_h8o

what do yall think??? pretty kool eh? when it starts pulsating the motor jerks alot. after running it again i saw what causes this surging.... so much pressure builds up that it actually back flows the fuel, i know this cause i saw the liquid fuel in my bottle bubble from the gasses entering it. the lower fuel pressure dies down the flame, that causes lower cc pressure, allowing it to pump in more fuel, causing higher cc pressure again.....so that explains that mystery. now i just need to know how to keep that from happening.... hey, i just realized, isnt that what happens in a pulse jet? which is why you dont need to time the fuel input larry??? it does it all on its own? high cc pressure the fuel will not enter..... well no shit i sais to myself.... why did that just now come to me........jeeze think i was stupid or something..... larry am i right?
hooowee that was loud! do it again!

larry cottrill
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Redneck's Ramjet

Post by larry cottrill » Mon Jan 15, 2007 2:05 pm

redneck -

Yes, a pulsejet driven with low pressure fuel will do that.

From the video, it seems to me that you have adequate air volume, though I don't know if you're getting good, smooth coverage of your engine inlet. At times your flame looks rich at the bottom while burning properly (blue flame) at the middle and top of the exhaust stream. This could be a flameholder problem, or could be as simple as the airflow not hitting the inlet dead-on and straight with the centreline. The drawings Al Belli posted show the effect of this.

Impressive test, just the same!

L Cottrill

redneck
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Post by redneck » Mon Jan 15, 2007 5:57 pm

what kinda flame holder problem could cause this??????? not letting enough air through??? to much air???? i doubt that.... im going to make sure my airflow is straight across...... now why do you think i have enough air flow? shouldnt there be blue flame out of my tail pipe??? not the white flame i am getting.... correct? all the burn isnt taking place inside my cc like it should...... well i will see about correcting my airflow and see what difference that makes......
hooowee that was loud! do it again!

Zippiot
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Post by Zippiot » Mon Jan 15, 2007 6:06 pm

I finished welding up my jet last night, didnt take my time on most of the parts and I am trying something new with the flameholder. If it works yay if it doesnt then I lost a day or so...
Sailing Student- How do I know if my life jacket is tight enough?
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Sailing Student- Yes
Me- Then its too loose!

larry cottrill
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Redneck's Ramjet

Post by larry cottrill » Mon Jan 15, 2007 6:30 pm

redneck wrote:what kinda flame holder problem could cause this???????
Something a little off center, i.e. making the flow path asymmetrical. It wouldn't take much to pervert the flow off to one side, change the mixing action, etc.
now why do you think i have enough air flow? shouldnt there be blue flame out of my tail pipe??? not the white flame i am getting.... correct? all the burn isnt taking place inside my cc like it should...
You have a couple of moments in the video where you basically got hot blue flame. This is undoubtedly where you were cutting back on fuel. The white flame is happening where you're driving in excess fuel for the air you have. This will generally result in combustion behnd the engine, because there isn't enough air inside the engine for all that fuel! Of course, that could be interprepted as "not enough air", and that wouldn't be wrong. It's just that when you were getting the roaring blue flame with all the air you had available, it looked like pretty good running (except for the asymmetry)!

L Cottrill

redneck
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Post by redneck » Mon Jan 15, 2007 6:57 pm

hmmmmm, thanks larry...........
hooowee that was loud! do it again!

redneck
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Post by redneck » Mon Jan 15, 2007 7:24 pm

well i just watched some of my other vids and i see what you are saying about non uniform air flow, in some vids the blue is on the bottom and in others the blue is on the top. i need to put my blower in a vise to hold it still...... by the way..... i put a copper evaporation coil in my cc for future liquid runs and i now get some really cool green flames......
hooowee that was loud! do it again!

Zippiot
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Post by Zippiot » Mon Jan 15, 2007 7:32 pm

Yeah I'm going to wind some 16 gauge copper wire in my cc when I get a chance, cant resist

My new jet is so shottily cut...I hope it runs
Also the flameholder is something I have never seen before so it may not work at all
Sailing Student- How do I know if my life jacket is tight enough?
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Sailing Student- Yes
Me- Then its too loose!

redneck
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Post by redneck » Mon Jan 15, 2007 9:22 pm

well any tube will blow out fire if you get enough turbulance..... or have slow enough moving air... so to a degree it probably will work.... what ever it is.........
hooowee that was loud! do it again!

Zippiot
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Post by Zippiot » Mon Jan 15, 2007 9:28 pm

best way to describe it would be a squid with a bunch of cuts in is head...
Gonna test it later today, once I finished my fueling set-up
Sailing Student- How do I know if my life jacket is tight enough?
Me- Can you breathe?
Sailing Student- Yes
Me- Then its too loose!

redneck
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Post by redneck » Mon Jan 15, 2007 11:07 pm

sounds interesting.................
hooowee that was loud! do it again!

Jim Berquist
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Ram Jet forum

Post by Jim Berquist » Tue Jan 16, 2007 12:28 am

At least you guys are getting stuff done...

It's so cold here you can't work outside for more then about 1/2 hour.

It was 7 degree F this morning.

To top off the cake, My place of work is talking about closing 31 march this year due to production cost and foreign interest.....

I may have to go Socialist and collect unemployment for a while..

That Sucks...

Jim
WHAT TO FRAP, IT WORKED![url=callto://james.a.berquist]Image[/url]

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