General Ramjet Info Please

[thecheat]

Actually I think they made the pulse-jet out of ceramics, but, the intake was too small, and it cracked.

About the cement stuff, wouldn't it be a bit rough? I'd think you'ld have problems with just air resistance... (this would be if you made the whole jet out of it)

PS: would it be possible to drill some holes and let the cement go through them to keep the metal in place? It would probably snap I know, but, it might be worth a try.

[Zippiot]

There are many types of refractory that can wistand the heat, but most are fragile especially when thin!

Grab some durhams rock hard water putty, it will withstand upwards of 1200 easily and holds pretty well. But it goes through 2 stages of decomposition, one at 400 and another just above 1200, might smell kinda like sulfur...

Never use pcc (portland cement) as it has no desireable qualities over 1000.

A possibly option I have been toying with is a mix of silica sand and dolomite. Both can be found at any garden store. When mixed together in a 50/50 ratio and with just a bit of water it holds decently for a while. The trick is to get the dolomite and quartz hot enough to sinter into palce. This is tricky, but once done it is as strong as any furnace cement as can hold in almost twice the temperature!


You will need prolly a 1 cm gap to use any type of refractory as a glue...the stuff just isnt stable below that. Look for 2 cups that have this gap and a lip or something so that the refractory isnt holding down a smoothe piece of metal. A nice groove or lip should help.


Or do as I did and find cups that fit together so well that when one is heated to 50 and the other stuck in the freezer, they can be pushed together never to come apart! Too bad my flamehodler melted and flew out the back or else the thing would still be in use.

[ZVWOLF]

okay... went shopping yesterday. (WOW! you all say) Anyway i found some Fire cement... really just a type of putty that can withstand 1500 celcius of heat. It should do the trick but only experminentation will tell.

Just gotta get a nice flame holder now.

Fuel inlets. I want to expermient first with propane. If the ramjet works i am going to build another one and use it with bio-desiel. With gases i suppose you just use a pinvalve like in maggie mugs. I suppose if i want to use bio desial i am going to have to get a small fuel pump and some sort of one-way valve... Correct?

[Zippiot]

The simplest liquid fuel system you can design is a water bottle with a hose guled to the cap. Squeeze hard!!

The system actually works quite well, and once pressure is up you can feel it getting much ahrder to squeeze the bottle. My maggie muggs could run off of a squeeze bottle for almost 45 seconds! Doesn't seem like a long run but for simple fuel testing it works great.

What I then did was buy some coper tubing the same size as the hose coming from the water bottle. You should have at least 6 inches of copper pipe coming out of the jet before you attatch the rubber (or whatever palstic) fuel line. This allows for some cooling, otherwise your tubing will melt.

There are also some extremely simple fuel injectors you can make if interested :)

Late for class no time to spell check!!!