The Great Ramjet Challenge!!!

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Jim Berquist
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subsonic Ram Jet

Post by Jim Berquist » Fri Jan 19, 2007 12:20 am

Zipp:

In a sub sonic version, what is the main differences? Just the intake right? Larger intake and reversed from divergence to convergence? That is what I am attempting with the Can Man.....


Jim
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Zippiot
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Post by Zippiot » Fri Jan 19, 2007 12:29 am

THe inake flameholder and exhaust have to be different...which is prettymuch the entire ramjet...

A subsonic ramjet does not require a cone in the intake to improve compression, and a convergent-divergent nozzle generally doesn't positively effect performance. There are so many different types of flameholders for supersonics but little has been explored in the subsonic ramjet, except in this forum subby's are rarely if ever used at the moment.

Look up a cutaway of the thor ramjet, you will see it looks almost nothing like our rammys, or check the nasa website and see a few nice 3d iamges (they are all supersonics on the nasa site). Some supersonic ramjets dont even need a convergent nozzle, just a divergent gives more than enough to propel it forwards.

Made some progress of my turbine today but not much on the ramjet, its hard to do two interesting projects at once!!!
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Sub sonic

Post by Jim Berquist » Fri Jan 19, 2007 12:48 am

I am trying to get the Can Man to run behind the Little Beast that Eric built. I am not using a Divergence front end. That may be why it melted down the first run. The Beast is surly putting out super sonic air at about 4 " away.....

I should modify the drawing ehhhh?


Jim
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Zippiot
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Post by Zippiot » Fri Jan 19, 2007 12:56 am

You do have a divergent intake...its just inverted!

Should work in theory but might cause a bunch of strange turbulence, but if meltign is you problem use thicker metal or a different steel (you were using steel right?). Some other people here know which metals have higher melting points.

I would say change the flameholder to something similar to a conical baffle. It is prettymuch an empty cone, it will help with fuel mixing and change the pressure.
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Post by Jim Berquist » Fri Jan 19, 2007 2:17 am

look at the zip! It's a curle inward with a cone flame holder...

My Idea was to take a little air and compress.....

I did not realize that the Beast could through that much hot air!!

It throughs a lot of air...Mabe I should add a seond flame holder of the screen type....Move the injection into the C.C......?


Jim
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Post by Zippiot » Fri Jan 19, 2007 3:48 am

Maybe move them to the cc and have them face the stream of air from the pj (since it blows that hard and fast the fuel should be blown back into the cc and mixed in the process). I saw you zip and I still think the flameholder should be changed to one of these:
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can man

Post by Jim Berquist » Sun Jan 21, 2007 5:29 pm

The flame holder and front end servived the trip: The C.C. did the melt down...

I am using some loctite 7452 cans. They have a good angle on the cone and are of the approx good size for the little P.J.....

I injected the fuel in the first, or intake section........

If I injected in the C.C. it may had cooled it better and lived...

I think the injector in the intake mixed to good and could have ran it too lean....that could have rased the temps in the C.C.

If you look at the one pic I posted of the parts, the tail side of the flame holder is crusty and burnt... I want to use the cans as they are light and cheap!!!

End Game is to measure the THrust and see if it is a gain or loss for the P.J.
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Post by Zippiot » Sun Jan 21, 2007 6:57 pm

I have found many thin stainless parts recently, like a little sugar shaker and also many stainless mugs. That is your best bet for something light that wont melt or get all crusty...but welding thin stainless is quite a pain
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yep me too on little

Post by Jim Berquist » Sun Jan 21, 2007 7:24 pm

Yea! I will move to C.C. and hope fore best....


I think it will work out for the best....

I really think it over heated due to To the front end feed!!!

It mixed to hard and got lean.........Next version will be C.C. burne..

Jim
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Zippiot
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Post by Zippiot » Wed Jan 24, 2007 4:53 am

Well guys at nearly 20 pages and just over a month it looks like the great ramjet challenge should set a due date.
I say 2 weeks from today should be the final day (argue your opinion for a final day here if you think it should be different), making it about 2 months since I announced the challenge!

Now remember, since it looks like only a few people have completed successful thrust-producing ramjet that you should not be discouraged! 2 weeks is plenty of time to get a rammy running. I myself need to throw together one that actually works...

2 weeks from now post your results, including:
3-view of the jet (pictures please)
Any drawings you would like to share
Chosen fuel and fuel delivery
Thrust achieved (any reasonable measurement method is ok, for pj powered rammy please show thrust with and without ramjet running)
Additional info appreciated, like past models or changes to design

It has been a good run (minus the explodsions and angry neighbors), good luck and thank you for participating!

Maybe the great pj challenge next?

PS: mild steel+rain=rusty ramjet sitting in my backyard...
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Post by redneck » Wed Jan 24, 2007 9:20 am

NNNOOOOOOOOOOOOooooOOOOO!!!!!!!!!! i cant do it zippy!!!!!!! i just cant do it in two weeks... (insert scottish accent) admit it........ this is all your wifes fault....... she is the one that wants it to end.... hmmmm manybe your wife talked to mine.... lol it is a conspiracy..... wifes agaisnt pulse-jets.com ( new web site comming to a server near you! ) anyway i havent worked on my jet in awhile now.... give yall all one guess why and the first guess dont count...... it burnt down!!!!!!!!!!! lol jk, its my wife.... who wishes it would burn down.... i think with me in it too lol. so i reckon i will now begine living in my garage again for days on end getting high on map gass, propane, and paint thinner. yall ever seen redneck puprle elephants before? ok i reckon i shouldnt drink before posting anymore... yall have a nice night........
hooowee that was loud! do it again!

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Post by Zippiot » Wed Jan 24, 2007 5:43 pm

Well when would you like to set the date?
Sailing Student- How do I know if my life jacket is tight enough?
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Me- Then its too loose!

Jim Berquist
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dead line Eaaa!

Post by Jim Berquist » Thu Jan 25, 2007 1:09 am

Zippiot :

I too am going through some life changes! I could do with a few more weeks. My job is taking a shit and the weather is the worst then in a while. My wife, god bless her is cool with it and even enjoys my Desires.......

P.J ,,,,,,,,Wife?,,,,,,,P.J.?,,,,,,,,Wife,?,,,,,,,,P.j.?,,,,,,,,Wife.?...............P.J.,?,,,,,,,,,,,,,,,,,,,,,,,wife,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,p.j.,,,,,,,,,,,,,,,,,,Wife,!!Wife!!,Wife!!,Wife,!!?,,,,,,,,Desire Wife then P.J.

Global Warming my @#$$!!!!!!!

Jim
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Hahah

Post by Irvine.J » Thu Jan 25, 2007 1:12 am

HAHAHAHHAHAHAHAH No drink it up that was the funny post EVER! Your right it is a conspiracy your wife has obviously been chatting to my GF to tell get on our backs...and I quote verbatim...
HER:"Your spend more time with your stupid rockets then you do with me!"
ME: "Dont be silly! And they are JETS honey. "
HER:"Jets then whatever!"

Hahaha, I too better lay off the Merlot for a while.
This has been edited to spare my life....

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Post by Eric » Thu Jan 25, 2007 3:22 am

HAHAHA yes you wouldnt want her to accidentally click on this thread in the explorer history and see that! :P

I should have my final entry done by then. .016" stainless with excessively high power to weight ratio :D

Eric
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Talking like a pirate does not qualify as experience, this should be common sense, as pirates have little real life experience in anything other than smelling bad, and contracting venereal diseases

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