mikah

Oh well, thanks for the info.

So are you telling me I won't get that ultra impressive sound of compression and expansion that I'm looking for? Cause that's all I really want out of this first engine, no real movement or performance, but a demonstration of principles.

I never said anything about a cross-section or volume or surface area, and the side is the slant, also I'm not sure where you're pulling triangles from, since we're working in three-dimensions. I'm saying if you have a whole cone, a standard right cone, the sides should move away at a specific rate for every angle the vertex should be, so with that knowledge there should be an equation to find your height using only diameter and opening angle.

Leader Bee, I already built a valveless pulsejet. CaptainPanic, wouldn't the leaf blower be simulating forward movement though, considering I haven't attached it to my jet. From what I've come to understand, any air entering the inlet is compressed by the geometry of the design, it's mixed with fuel, then ignited, the air expands according to what sort of fuel you have and what kind and how much gas is produced by the reaction, the air will move in the path of least resistance, which is the nozzle which forces a large amount of air through a much smaller hole, and that creates forward thrust. Now most ramjets get the airspeed to start the reaction from another source, some missiles have ramjets and the jets they are attached to get them up to speed, I think cruise missiles have them and they use a rocket of some sort, I don't know what kind but several are often used with ramjets. All I'm really trying to do, is make a ramjet to test my ability in planning, solving equations, and welding according to very specific instructions. The pulse jet was a section of pipe with a plate welded over one end and two smaller diameter pipes attached, one for fuel intake and one for air intake. It fired up quickly and sustained. Now I want a harder challenge, which is the ramjet, after this I'm focusing on a coil gun and a submarine, then I will try and make a turbojet. I just enjoy dicking around with my friends and this is how we do it since our parents stopped buying chemicals to play chemist with.

So you have a right cone with a certain opening angle, shouldn't there be an equation to find the height for a certain diameter? Seeing as the sides move away at a constant rate there should be some sort of equations realting angle to diameter.

Well shouldn't providing the airflow cause compression, once proper compression is achieved shouldn't the reaction sustain? The air is taken in, mixed with fuel, ignited and compressed, then the gas is expelled through the nozzle creating low pressure in the combustion chamber which brings in more air that mixes with more fuel and so on. Either way, I have seen static ramjets made where the air is fed by a leaf blower, and I would like to make one like that to test the ramjet design and see how a realworld model functions.

Well to start it I would use like a leaf blower or compressed air to get the air moving so I can start the reaction so it will sustain, once it sustains it should produce a small amount of thrust, with the cluster this should be enough to get me moving at low speeds, I'll have the diffuser cut to spin the incoming air which stabilizes the compression at low speeds, if what I read was true. But either way I would like make a static ramjet as I already made a valveless pulse jet.

I'm trying to build a subsonic ramjet to try and get the technique down so I can make a cluster to put on a go-kart, bicycle, or lawnmower. I've looked all over the internet and the only reliable science and math I can find is for supersonic ramjets or from a hobby forum that doesn't really seem to understand math. So basically what I am trying to find out is how narrow my diffuser needs to come down to and the length of diffuser, how that relates to the combustion chamber and nozzle, and the best shape for my fuel injector. If you can give me the equations it would be greatly appreciated.