Also dude i forgot to mention, Those holes are very small, if you find its not putting out as much throttle as it should, or is flaming out very quickly, I'd try opening up each of those holes a great deal. I had 4 atleast 1 mm holes in mine, seemed to work a lot better better then lots of tiny ones.
Since then I got my hands on some kick ass brass 360* injectors from a garden supply company, the perfect ramjet fuel injector for that complete flameholder coverage, if you have a dremel you can also change the spray angle, if your interested I can post you a couple, they are pretty cheap, and some 1/4 inch copper pipe along with it, email me if interested.
My Maggie Mugs Clone
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Bobthemonkey
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Hey Irvine.J,
can you post a picture of those injectors? I probably wont use anything like that for this engine, but I gotta think ahead!
Anyway, the engine is almost ready for testing! I built the support stand today and all it needs is a fuel line, what do you guys recommend? I recently went through all of our Fourth of July stuff and found five sparklers whitch I will use.
-Bob
can you post a picture of those injectors? I probably wont use anything like that for this engine, but I gotta think ahead!
Anyway, the engine is almost ready for testing! I built the support stand today and all it needs is a fuel line, what do you guys recommend? I recently went through all of our Fourth of July stuff and found five sparklers whitch I will use.
-Bob
Never take life seriously. Nobody gets out alive anyway.
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Bobthemonkey
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Its Done!!!!!
I have completly finished the entire thing and I bolted it to the test stand and finished the fuel system.
Its ready to test, all I need is a place to test it...
I have completly finished the entire thing and I bolted it to the test stand and finished the fuel system.
Its ready to test, all I need is a place to test it...
- Attachments
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- Bolted to the test stand
- ramjet003-small.jpg (271.71 KiB) Viewed 13206 times
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- The fuel system (made from an old torch head)
- ramjet009-small.jpg (298.87 KiB) Viewed 13208 times
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- My epoxy (completly gone)
- ramjet028-small.jpg (224.21 KiB) Viewed 13207 times
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- Fuel inlet detail
- ramjet042-small.jpg (244.62 KiB) Viewed 13208 times
Never take life seriously. Nobody gets out alive anyway.
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larry cottrill
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Bob -
That's fabulous! Now, a reminder of a couple of things to keep in mind:
First, be sure you establish right away whether you have sufficient air. If combustion ends up taking place ahead of the flameholder, it means your air isn't fast enough. So, pay attention to this right away, as soon as you have combustion established and stable.
Second, be aware that if your air fails for some reason (e.g. tripped circuit breaker), you will have a lot of propane flowing, and a lot of fire will be rolling out of the FRONT of your engine. Try to work a gas type ball valve into your outfit, between the tank needle valve and the hose. Start out with this valve full open and use your needle valve for control. Then in the unlikely event of air supply failure, use the ball valve as a "quick shutoff" before things get out of hand. You'll want to then shut off the needle valve too, of course.
Good luck! Run safely!
L Cottrill
That's fabulous! Now, a reminder of a couple of things to keep in mind:
First, be sure you establish right away whether you have sufficient air. If combustion ends up taking place ahead of the flameholder, it means your air isn't fast enough. So, pay attention to this right away, as soon as you have combustion established and stable.
Second, be aware that if your air fails for some reason (e.g. tripped circuit breaker), you will have a lot of propane flowing, and a lot of fire will be rolling out of the FRONT of your engine. Try to work a gas type ball valve into your outfit, between the tank needle valve and the hose. Start out with this valve full open and use your needle valve for control. Then in the unlikely event of air supply failure, use the ball valve as a "quick shutoff" before things get out of hand. You'll want to then shut off the needle valve too, of course.
Good luck! Run safely!
L Cottrill
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Irvine.J
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Mate, thats one really nice peace of work, you can run it anywhere you can get a big fast blower to drive the thing! I'm very impressed, and I just know it will go hard.
I do most of my stuff in the garage, its great fun!
As for the injector, mate its just a brass 360* water spray tip, brazed onto 3/16th SS line. I usually drill the hole out a bit so i can get all the flow I desire without it coming out at an insanely fast speed. Its like a 5 dollar part and you could probably find them at wallmart garden section. It has a slight angle so the gas is at least going the right way, and is a very thin "Spray" of gas that incoming airflow just picks up mixes bloody well before even hitting the flameholder. You can also get in there easily with a dremel cutoff disc if you want it at a steeper angle, long and short is they work very well, and if your desperate, pm me and i'll arrange to send you one on some 3/16th stainless line.
I do most of my stuff in the garage, its great fun!
As for the injector, mate its just a brass 360* water spray tip, brazed onto 3/16th SS line. I usually drill the hole out a bit so i can get all the flow I desire without it coming out at an insanely fast speed. Its like a 5 dollar part and you could probably find them at wallmart garden section. It has a slight angle so the gas is at least going the right way, and is a very thin "Spray" of gas that incoming airflow just picks up mixes bloody well before even hitting the flameholder. You can also get in there easily with a dremel cutoff disc if you want it at a steeper angle, long and short is they work very well, and if your desperate, pm me and i'll arrange to send you one on some 3/16th stainless line.
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Bobthemonkey
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Thanks for the feedback everybody!
Irvine- I dont really need any injectors right now, just thinking ahed to my next project!
I dont think I want to install a ball valve in the fuel line because I will be holding the needle valve the whole time anyway and my fuel line will be swinging around, so by the time I actually reach the ball valve and shut it off I could have shut off the needle valve a long time ago.
Unfourtunatly garage testing is not possible because I live in a historic neighborhood that has regulations for how often to tie your shoes. Also, my neighbors are the kind of people who just dont have enough to worry about and would probably call the Police, the Fire Department, and the Army all in the space of 5 minutes after I turn it on. I'm thinking I will try it at a city park that has power, or some other secluted location.
Testing should be Soon! (I hope)
-Bob
Irvine- I dont really need any injectors right now, just thinking ahed to my next project!
I dont think I want to install a ball valve in the fuel line because I will be holding the needle valve the whole time anyway and my fuel line will be swinging around, so by the time I actually reach the ball valve and shut it off I could have shut off the needle valve a long time ago.
Unfourtunatly garage testing is not possible because I live in a historic neighborhood that has regulations for how often to tie your shoes. Also, my neighbors are the kind of people who just dont have enough to worry about and would probably call the Police, the Fire Department, and the Army all in the space of 5 minutes after I turn it on. I'm thinking I will try it at a city park that has power, or some other secluted location.
Testing should be Soon! (I hope)
-Bob
Never take life seriously. Nobody gets out alive anyway.
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Bobthemonkey
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Success! (or is it faiure?)
Well, I ran it yesterday using propane as a fuel, fueling was nice and easy and I got a lot of flow right away when I turned it on. I started I out rich and worked twards lean combustion. Then I noticed sompthing was wrong. I decresed the fuel flow and it got a lot quieter all of a sudden. Isnt it supposed to get louder with lean combustion? I eventully shut it down and was about to start it up again when I noticed the engine rattled when I moved it. I looked inside and saw the flameholder had detached and there was molten metal splattered down the intirror of the nozzle. I ended up having to soak it overnight in water to detatch the two sections (Restabond 907GF is water soluable) and I saw the true extent of the damage.
I would not recomend using this epoxy to bond any sort of engiene because it does break down in high temperture and is not very good at sticking to things, not nearly as well as JB weld.
As it turns out the metal I used to block off some of the holes in the flameholder was aluminum and it can easly be melted with a propane torch.
Any suggestions anyone?
Bob
Well, I ran it yesterday using propane as a fuel, fueling was nice and easy and I got a lot of flow right away when I turned it on. I started I out rich and worked twards lean combustion. Then I noticed sompthing was wrong. I decresed the fuel flow and it got a lot quieter all of a sudden. Isnt it supposed to get louder with lean combustion? I eventully shut it down and was about to start it up again when I noticed the engine rattled when I moved it. I looked inside and saw the flameholder had detached and there was molten metal splattered down the intirror of the nozzle. I ended up having to soak it overnight in water to detatch the two sections (Restabond 907GF is water soluable) and I saw the true extent of the damage.
I would not recomend using this epoxy to bond any sort of engiene because it does break down in high temperture and is not very good at sticking to things, not nearly as well as JB weld.
As it turns out the metal I used to block off some of the holes in the flameholder was aluminum and it can easly be melted with a propane torch.
Any suggestions anyone?
Bob
- Attachments
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- The flameholder with all the molten metal
- Ramjet run_1005_small.jpg (98.31 KiB) Viewed 12973 times
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- What I saw looking down the engine
- Ramjet run_1007_small.jpg (61.86 KiB) Viewed 12976 times
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- The "After" picture
- Ramjet run_1011_small.jpg (76.38 KiB) Viewed 12976 times
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- Epoxy flaking
- Ramjet run_1012_small.jpg (78.35 KiB) Viewed 12975 times
Never take life seriously. Nobody gets out alive anyway.
epoxy replacement
I know the idea behind the maggie is a weld-less ramjet but have you thought about brazing your flameholder in place? It should hold up better than the epoxy but is still doable with only a propane torch (mapp gas would be better)
I would guess thats also the reason that it got quieter as you leaned the fuel back, the flameholder came loose and allowed the air/fuel mix to burn further down in the combustion chamber.
-Aaron
I would guess thats also the reason that it got quieter as you leaned the fuel back, the flameholder came loose and allowed the air/fuel mix to burn further down in the combustion chamber.
-Aaron
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Bobthemonkey
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Hey gerat idea!
How exactly do you braze?
Ive got a Mapp gas torch and I think I can get some brazing rods.
Wha type of rod do you recommend? I might be able to put the whole thing togeather with brazing if that is possible, it would be cheaper than buying more epoxy and would work better too.
-Bob
How exactly do you braze?
Ive got a Mapp gas torch and I think I can get some brazing rods.
Wha type of rod do you recommend? I might be able to put the whole thing togeather with brazing if that is possible, it would be cheaper than buying more epoxy and would work better too.
-Bob
Never take life seriously. Nobody gets out alive anyway.
brazing
Brazing is almost like soldering but at a bigger scale.
Heat both sides to near red, touch the brazing rod to the parts and watch it melt and flow into the joint. Most come with a paste flux on the outside of the brazing rod so the only prep needed is to make sure the joint is very close and clean (brazing doesn't work over large gaps between materials) It may require you to heat the brazing rod as well if the parts are very thin (like in this case). Is so, heat the parts first and then place the brazing rod on the joint and heat it until it starts to melt into the joint. After it cools, clean it up with a wire brush (either hand held or a wheel) If it doesn't clean up too well, you may need to grind it down some. I've had good luck finding brazing rods at places like Lowes and HomeDepot. Check in the larger home improvement stores near you.
Naturally the melting point of the braze is going to be lower than the materials you're joining but not so low that it would be unusable in this case. For something like the flameholder in a ramjet it should work but not for something like the combustion chamber for a valveless PJ. The PJ would get too hot and melt the braze again.
The suggestion for mapp gas over propane is that mapp gas burns hotter and so should heat up the materials faster. You *could* use it as the fuel in your ramjet as well, but I'd test it well first. It could burn too hot and start melting things. (it will melt 26 gauge mild steel after a minute or so)
-Aaron
Heat both sides to near red, touch the brazing rod to the parts and watch it melt and flow into the joint. Most come with a paste flux on the outside of the brazing rod so the only prep needed is to make sure the joint is very close and clean (brazing doesn't work over large gaps between materials) It may require you to heat the brazing rod as well if the parts are very thin (like in this case). Is so, heat the parts first and then place the brazing rod on the joint and heat it until it starts to melt into the joint. After it cools, clean it up with a wire brush (either hand held or a wheel) If it doesn't clean up too well, you may need to grind it down some. I've had good luck finding brazing rods at places like Lowes and HomeDepot. Check in the larger home improvement stores near you.
Naturally the melting point of the braze is going to be lower than the materials you're joining but not so low that it would be unusable in this case. For something like the flameholder in a ramjet it should work but not for something like the combustion chamber for a valveless PJ. The PJ would get too hot and melt the braze again.
The suggestion for mapp gas over propane is that mapp gas burns hotter and so should heat up the materials faster. You *could* use it as the fuel in your ramjet as well, but I'd test it well first. It could burn too hot and start melting things. (it will melt 26 gauge mild steel after a minute or so)
-Aaron
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Irvine.J
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More on brazing
Ok mate, couple of things also on brazing.
You can certainly braze stainless steel, but it is a little more difficult to make it stick. If you want a no fuss braze, make sure you use the 45% silver brazing rods, the 2% and 5% will do it, but its a touch more difficult. The 45% is quite expensive though! Anyway, if you want to use the cheap stuff, get yourself the blue high temperature brazing flux.
Now, score the weld with a bench grider or dremel, something quite rough, all the way around the braze area or the "Contact with braze" area. Braze wont stick well to the flat sheen surface of stainless. FLux up the area but not too liberally, just a decent amount, and wave the torch over the area you want to braze, you'll find a touch of heat around the area will help before concentrating the the heat initiate the brazing process, when its red hot, simply dab the braze rod on the join, and push lightly and watch it flow!. Always braze so the molten metal runs the direction (Into the join) you want. Keep the heat consistent, and work your way around.
Brazing I think takes about as long for me to tig, which isn't too long, but it requires patience and a little bit of practice. I use a propane torch and can braze anything, mapp or propane is much of a muchness in brazing.
When you get the hang of it, its actually quite a fast and enjoyable experience, and can stand up to 750*C, I used it in the front of my flame holders for a long time in the early days.
You can certainly braze stainless steel, but it is a little more difficult to make it stick. If you want a no fuss braze, make sure you use the 45% silver brazing rods, the 2% and 5% will do it, but its a touch more difficult. The 45% is quite expensive though! Anyway, if you want to use the cheap stuff, get yourself the blue high temperature brazing flux.
Now, score the weld with a bench grider or dremel, something quite rough, all the way around the braze area or the "Contact with braze" area. Braze wont stick well to the flat sheen surface of stainless. FLux up the area but not too liberally, just a decent amount, and wave the torch over the area you want to braze, you'll find a touch of heat around the area will help before concentrating the the heat initiate the brazing process, when its red hot, simply dab the braze rod on the join, and push lightly and watch it flow!. Always braze so the molten metal runs the direction (Into the join) you want. Keep the heat consistent, and work your way around.
Brazing I think takes about as long for me to tig, which isn't too long, but it requires patience and a little bit of practice. I use a propane torch and can braze anything, mapp or propane is much of a muchness in brazing.
When you get the hang of it, its actually quite a fast and enjoyable experience, and can stand up to 750*C, I used it in the front of my flame holders for a long time in the early days.
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larry cottrill
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Bobthemonkey
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Thanks for the feedback guys!
I dont think I will try to use that epoxy again, it tends to undergo chemical changes in high heat and turn red and flaky.
I think I might be able to get an Oxy-Acetylene brazing torch from the home depot for 40 dollars, would that allow me to have a much higher temperture braze?
Also, how long would I be able to run an engine brazed togeather with MAPP gas?
-Bob
I dont think I will try to use that epoxy again, it tends to undergo chemical changes in high heat and turn red and flaky.
I think I might be able to get an Oxy-Acetylene brazing torch from the home depot for 40 dollars, would that allow me to have a much higher temperture braze?
Also, how long would I be able to run an engine brazed togeather with MAPP gas?
-Bob
Never take life seriously. Nobody gets out alive anyway.
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Irvine.J
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Ok, it doesn't matter what you use to braze the engine with in terms of flame heat, the hottest braze I've seen at my shop is 850, which it well within propane torch range, the temperature of the braze depends solely on that, the melting point of the braze you use, not the flame heat. A propane torch is much cheaper then the oxy-acet setup. If you braze the flameholder, and that ring around the outside, it should hold for a VERY long time, I even doubt up there at the transition it will get hot enough to melt at all, but i've never run my ramjets for more then a few minutes at a time to be sure, though, i'd say well and truely long enough to have lots of fun.