# Designing a Pulse Jet Engine.

If you were to design a pulse jet engine where would you start?

How do you determine the diameter and length of the tail pipe?

How do you determine the diameter and length of the combustion chamber?

How do you determine the area of the air intake valve system?

How do you determine the burn rate of the fuel?

How do you determine the over all length and design of the engine?

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LURCH
I suppose I would start with fuel burn rates. That's because, as a private citizen, I have access to a very limted number of fuels, and can easily look up their burn rates at different mixtures. From there I could determine the area of the air intake, which would tell me how large thje valve assembly needs to be, and keep going from there.

Where do I look up the burn rate of fuel air mixtures?

How about a 35 lb thrust pulse jet engine with gasoline as the fuel.

Give me an example for calculating, doing all the math for this engine. If I can see an example and know where to find all the information then I can take it from there and do the math for other size engines. I would also like to use Alcohol as a fuel too. Methal or Ethyl.

FredGarvin
If you Google pulse jets, you will find a wealth of information. They are not difficult to design. However, having someone tell you how to do something doesn't teach you anything about it. You need to do the research and the digging.

http://www.pulse-jets.com/

If you Google pulse jets, you will find a wealth of information. They are not difficult to design. However, having someone tell you how to do something doesn't teach you anything about it. You need to do the research and the digging.

http://www.pulse-jets.com/
This information is worthless. I found this years ago. It is a bunch of plans other people have built. There is nothing her that teaches a person how to design their own. Anyone can copy other peoples plans. What I need is some scientific informations based on the laws of physics and formulas.

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RonL
Gold Member
This information is worthless. I found this years ago. It is a bunch of plans other people have built. There is nothing her that teaches a person how to design their own. Anyone can copy other peoples plans.
If you found this site years ago and still do not know anything about pluse jets, I have to draw the conclusion your a bit lazy.

If you found this site years ago and still do not know anything about pluse jets, I have to draw the conclusion your a bit lazy.
There are lots of plans there that is all I have found. Most of those plans are not good. They don't have all the demensions and some demensions are just numbers like 75, 40, 30, 25. So what is that, 75 what? 75 meters, 75 feet, 75 inches, 75 milimeters?

I have built a lot of pulse jet engines over the past 31 years. I have come up with my own formulas that work very well but I thing there has to be some physics involved here that can be used to design these engines and fine tune them to run at maximum efficiency.

I have book on Liquid fuel rocket engines they are all designed around the burn rate of the fuel. I think a pulse jet engine should be designed around the burn rate of the fuel but there is no data for burn rate in air.

I have been out of college 40 years, if you don't use it you loose it, I have forgotten more than I every knew. I wish I still have my old college fluid mechanics book seems to be there is some good information in there that I need.

RonL
Gold Member
There are lots of plans there that is all I have found. Most of those plans are not good. They don't have all the demensions and some demensions are just numbers like 75, 40, 30, 25. So what is that, 75 what? 75 meters, 75 feet, 75 inches, 75 milimeters?

I have built a lot of pulse jet engines over the past 31 years. I have come up with my own formulas that work very well but I thing there has to be some physics involved here that can be used to design these engines and fine tune them to run at maximum efficiency.

I have book on Liquid fuel rocket engines they are all designed around the burn rate of the fuel. I think a pulse jet engine should be designed around the burn rate of the fuel but there is no data for burn rate in air.

I have been out of college 40 years, if you don't use it you loose it, I have forgotten more than I every knew. I wish I still have my old college fluid mechanics book seems to be there is some good information in there that I need.
I only meant to be a little offensive in my comment, as Fred is a much respected member of this forum, you'll learn more about him and others that can help you, if you stay around awhile.
Please do, it sounds as if you have some info that can be of help to others.

I have to go for now but will be back later.

Check out the rules and forum guidelines, and stick around long enough to get to know a few of the people here.

RonL