What you want and what you GET... are 2 different things

[HPSCL]

One thing that truly puzzles me, is the inability to share information on how to actually design a pulse jet. Sure, there are plans out there... and lots of them. However, there is little to no information on how the dimensions and configurations of a particular design were finally made into a working model.

By working I mean; that not only does the engine actually cycle, but also puts out a measurable amount of thrust. How many videos have I watched (put out by people who seem to actually seem to know what they're doing) of a new design, only to see that even they, were having trouble getting it to run?

A couple of sites, like Cottril Cyclodone & Beck Technologies, actually offer FREE detailed plans to make a variety of different engines. However (again, with the "however") there is no information... not even a "hint", on how to feed the engine (design the fuel nozzle) after you build it.

The feeble point that I'm attempting to actually get to, is that; For years, I was a member of a "spudgun" forum. We designed and built pneumatic and combustion cannons, out of PVC pipe. There was always a lot of R&D floating around, but only a select few ever came up with an innovative design.

These innovative designs were almost always immediately shared with everyone else. Theories turned into a diagram. A diagram turned into a cannon. Not once, did anyone ever think to themselves: "You know... I put a lot of time and effort into this... it actually works and works even better than I thought it would... Hmmm... I could make a shitload of money, by selling plans to make it".

Big deal, right? But has anyone here ever launced a golfball... through both sides of a scrapped car? Or shot a basketball over 500 feet in the air? Or played with a full-auto tennis ball cannon? All of these designs, as well as many more, were all designed / built and then shared with everyone.

Some of you wanna make money selling plans, then so be it. But the ones that actually are offered for free, in my opinion, are incomplete. A mechanic is not going to tell you (over the phone) what is wrong with your car. But few people realize that even if he (would), he still wants to be paid, for his many years of experience. - If everyone knew how to fix their own car, then there'd be no need for the mechanic.

I've built 5 working pulse jets and had little to no clue as to what I was doing and why I was doing it, in the first place. They all had trouble achieving resonance. They all required an extensive amount of "tweaking" on the shape and diameter of the fuel nozzle. The only clue that I've relied on, is nothing more than the simple fact that the engine's intake pipe(s) length, should (b)not(b) be an even multiple of the tailpipe's length... and that's it.

I can get almost anything to run. You can see what it is or is not doing, as well as hear what it is or is not doing... and then experiment. But I'm not like one of those stubborn-ass mechanics, who'll (b)swear(b) that they can set the timing, on your old chevy small-block.. "by ear".

I would gladly pay the money, to receive plans in the mail... IF those plans were also to include the information on HOW they were designed, WHY they picked that PARTICULAR configuration... and then HOW they determined the fuel "jet" size. Was it all nothing more than just a lot of trial-and-error?
... Or do they somehow know something that's now considered "a trade secret"?

After reading threads like the one where that guy was pissed at Bruce Simpson (Bruce Simpson's book), for failure to produce and then failure to refund (especially the last page of the thread) I hesitate to gamble with my money, however little it may seem.

Any monkey can slap something together and then get it to run. But if the monkey now fully understood; not only how to make it run, but why it runs and then how to make it run even better... Then I guess the monkey figures he can move out of the jungle, by selling plans. The chimpanzee, the giraffe and the elephant can all just sit there and scratch their ass, while waiting for the monkey to share...

• ▪ You put money in this coconut and swing it over to me.
  ▪ I take money out of coconut and go back to watching the cartoon network on my new HD TV.
  ▪ You wait 2 moons.
  ▪ You send note in coconut, ask me; "Where my plans"?
  ▪ I send coconut back, tell you; Bought 40 banana dacquiris with your money, got raging case of Congo squirts and then wipe my ass, with plans...
  ▪ You send coconut back, asking me:" Well, can I just get another set of plans ???"
  ▪ I send you coconut back, with the Congo-squirt smeared plans.
  ▪ You demand refund...
  ▪ ... I watch cartoons.

I guess I'll just stick to making YUGOS and tuning them, by ear.

edited: Fore sevrul grammatikal airroars

[metiz]

One thing that truly puzzles me, is the inability to share information on how to actually design a pulse jet. Sure, there are plans out there... and lots of them. However, there is little to no information on how the dimensions and configurations of a particular design were finally made into a working model.

Every engine is different. Big, small, thermo, chinese etc. The information required to build a very effective and acoustically tuned engine is scattered over the internet in tiny chunks for you to put together. The reason no one is putting their theories on their plans is that it would take hundreds of hours to do so. Pulse-jets are deceptively complex; posting all the info would be like posting 4 years of engineering school in a single post. That and everybody makes their engines differently, in their own style. Nobody wants ther style to be copied and used (commercially) somewhere else.

By working I mean; that not only does the engine actually cycle, but also puts out a measurable amount of thrust. How many videos have I watched (put out by people who seem to actually seem to know what they're doing) of a new design, only to see that even they, were having trouble getting it to run?

There's a lot of trial and error to be put into any engine before it will properly run. This is yet another reason people do not want to share their info: Nothing comes for free. Nobody likes to hand out free information to everyone who comes when they have spend a lot of resources on their designs. Try asking for the plans to the new season F1 car and you're lucky not to be shot.

A couple of sites, like Cottril Cyclodone & Beck Technologies, actually offer FREE detailed plans to make a variety of different engines. However (again, with the "however") there is no information... not even a "hint", on how to feed the engine (design the fuel nozzle) after you build it.

Again, nothing comes for free. Do some research for yourself. That said, Beck-Tech plans usually have detailed information on how to fuel their engines

The feeble point that I'm attempting to actually get to, is that; For years, I was a member of a "spudgun" forum. We designed and built pneumatic and combustion cannons, out of PVC pipe. There was always a lot of R&D floating around, but only a select few ever came up with an innovative design. These innovative designs were almost always immediately shared with everyone else. Theories turned into a diagram. A diagram turned into a cannon. Not once, did anyone ever think to themselves: "You know... I put a lot of time and effort into this... it actually works and works even better than I thought it would... Hmmm... I could make a shitload of money, by selling plans to make it".

Respectfully, Pulse-jets and acoustics are a lot more complex then spud guns, A lot more time is spend perfecting and testing designs. There are also some definite commercial interests in non steady combustion units. Some people share their information, some people run to the pattent office to prevent just that

Some of you wanna make money selling plans, then so be it. But the ones that actually are offered for free, in my opinion, are incomplete. A mechanic is not going to tell you (over the phone) what is wrong with your car. But few people realize that even if he (would), he still wants to be paid, for his many years of experience. - If everyone knew how to fix their own car, then there'd be no need for the mechanic.

Exactly. So why are you complaining about the stuff you get for free? If you ask around you will get injector info. If you look around, you will find injector info. Do your own research to find a good injector or go with the hands-on aproach like the people who have shared their information for free and find out yourself. Then post your own results and you might get a bit more help from other people.

I can get almost anything to run. You can see what it is or is not doing, as well as hear what it is or is not doing... and then experiment. But I'm not like one of those stubborn-ass mechanics, who'll swear that they can set the timing, on your old chevy small-block.. "by ear".

By designing and running pulse-jets you will gain knowledge. After a dozen or so engines you WILL be able to tell if the engine is running smoothly or needs some work. question is, are you prepared to put in the time.

In 4 years time I have build about 40 engines. By now, after a LOT of trial and error I can, while using the smallest amount of math, design a pretty decent engine just by eyeballing the design on a cad program and making adjustments acording to what I see.

After reading threads like the one where that guy was pissed at Bruce Simpson (Bruce Simpson's book), for failure to produce and then failure to refund (especially the last page of the thread) I hesitate to gamble with my money, however little it may seem.

Then try one of the MANY FREE plans and spend like 10 bucks to figure out your own injector. Or start reading previous threads for the right information

Any monkey can slap something together and then get it to run. But if the monkey now fully understood; not only how to make it run, but why it runs and then how to make it run even better... Then I guess the monkey figures he can move out of the jungle, by selling plans. The chimpanzee, the giraffe and the elephant can all just sit there and scratch their ass, while waiting for the monkey to share...

OR they could get off their asses and put some f*cking effort in it themselfs before critizing the monkey for not publishing the fruits of it's hard, tedious laybour.

Before you start criticizing the free information given by the people here you might want to put in some research, share some information and maybe publish a plan or 2 yourself

[PyroJoe]

Which specific details of design would help you the most?
Barring this last post, it looks like you were sorting things out reasonably well.
What would you like help with?

[Eric]

The FWE plans will run off a straight tube injector, nothing fancy needed.

Our CD has the plans for the injectors for larger more complex engines, and 50 or so pages of PDF builders guides.

Like Metiz said, they are deceptively complex, you can provide all the information needed to build one on the back of a napkin, but to explain how to design just one type, would take a trees worth of paper.

I've been writing a book over the past 8 years, it started as a 60 page graduation project, and has mutated into a multi-volume many hundred page monster. Its still not done, I feel there is so much more I can add.

Unfortunately I have bills to pay, and cant live off of 16 cent ramen noodle soup packages alone, in a perfect world all information could be shared freely... Welcome to the slave labor camp called Capitalism.

[Jutte]

Hi HPSCL,
Pulse jets - you can take them as far as you want.
You can find stuff on this site for the basic "Hey I just want an engine that makes noise"
to the ins and outs of the science of 'Unsteady Combustion'.
Free plans - dude there are heaps here . ( or you can do a net patent search as well )
Need help? - just ask or use the search function.
Want to read about what actual jet propulsion scientists say regarding research papers- use the search function.
Of course you're going to get bandits ripping people off - just google "water powered car plans" -suggest you don't spend your money -
that however doesn't mean it's not real.
( And before everyone jumps on me for that one - yup been there done that,seen it,
got the "t" shirt etc etc blah blah blah - it works - and to be frank I don't really care what you believe )
Also there are people that actually do make money selling Spud Guns - (I do know the US Army engineers bought a few ) -
....and does a green apple through a car count?
Also like Eric - I don't like eating those noodles - so I do see where he comes from.
So HPSCL - you can always spend the good part of ten grand and get yourself a flash
new turbine to play with - or spent under twenty bucks , have heaps of fun (learn new stuff) - and make something that can
make your wife's mountain bike the only pulse jet bike in the neighbourhood.
So welcome to life and the wonderful world of pulse jets - "where what you get out is louder than what you put in!"
Shoot - I should patent that last phrase...

[HPSCL]

Gentlemen,

This site has offered me help, in the past. And Eric (Beck Technologies), of all people, answers email inquiries lightning fast. I have no trouble now designing and getting an engine to run. What would be nice, was if I actually had a clue as to what I was doing.

One of the several points I was trying to make, was that people like this guy who wanted to buy plans from Bruce Simpson, to make two different pulse jets, could have just saved a lot of time and frustration, by building one off of any one of the several free plans that exist out there in cyberspace.

Of course, there was nothing in my post that even implied that. What really does suck monkey-ass, was that he claimed to have gotten the run-around... and for quite some time. I don't think that anyone would be stupid enough, or spiteful enough, to publicly trash a business, unless they felt as though they were severely wronged. And I don't give two squirts, about that BS about refunding the money... on both their parts. - On Bruce's part, he should've simply provided what the client asked for- plans for a 200lb. pulse jet. And on the client's part, if he had already filed a complaint with Paypal, then just be patient... AGAIN and wait for Paypal to reimburse you.

Another point was that if someone is willing to share detailed plans... and by "share", I mean for FREE, then go the one tiny extra step to post the recommended injector size. No big deal, but as I vaguely implied, I get everything to run "by ear".

Respectfully to everyone here, as well; "spudguns" are a tad less complex than pulse jets. But from a design perspective, they are quite similar. - On a combustion cannon, if you make your barrel too long, it slows the projectile. It took the monkey's inbred uncle to figure out why. If you make the barrel too short, then lots of fuel/air are simply wasted, as the projectile never even had a chance to get near it's potential speed. Spark location matters, because if it's too close to the breech of the barrel, you'll plop the projectile out with a dull "whoosh".

I could go on and on about PVC Cannons, but who really cares, in a pulse jet forum? The point there, was that I designed the first "hybrid" cannon (Compressed air and fuel) and also, a full-auto BB Machine gun that had no moving parts and also... no internal parts. - Thought briefly about "selling working models" and was quickly dissuaded by the fact that little Johnny would accidently blow up the garage, or shoot all the neighbor's windows out... and then sue me, for providing the means to do so.

But, hey- That was me. For anyone else that wants to sell plans, models, engines or even coconuts... I wish them the best of luck. The people that can't figure out how to get inside of the coconut, probably shouldn't be eating it, anyway. But don't offer free plans to make a machine that'll crack the coconut and then fail to tell you that it needs a four prong European plug and exactly 103.017 volts and a "micro flux capacitor" to operate, or else the motor won't turn.

As I previously stated, I wouldn't hesitate to gamble with some money and buy plans from someone like Beck... IF, on his website. he had an actual "add to shopping cart" style of an online store. Who wants to be bothered with an emailed order form, email inquiries and no actual location of proprietor? This is nothing more than just constructive criticism, from a potential consumer.

Something as simple as a "ballpark" C:B ratio, as we use the term, in our spudgun world, would help all the other monkeys to actually design their own noisemaker. More specifically: If your CHAMBER is "X" diameter, by "Y" length, then make your tailpipe "x" diameter, by "y" length. If you can't get a hold of X, Y, x, or y diameter pipe, then if you simply make the combustion chamber at "X" volume, then the tailpipe needs to be "Y" volume. Then kiddies, at the very least, it'll resonate.
Suggested Intake diameter, length, volume -etc. are a whole other nightmare of top-secret info, that is just way beyond the monkeys feeble comprehension, so why even bother?

Could a simple gas law, such a p¹ x v¹ = p² x v², apply to the aforementioned C:B ratio? And why is it, that if you inject 40psi out of a .030" opening, it is not the same as 30 psi - out of a slightly larger opening? Maybe the speed at which the gas enters a given engine configuration, needs to match the speed at which the burning gases are resonating (cycling) at? Maybe... I'll just sit in the corner with my coconut for a while, and try to figure out how to get 103.17 volts, out of this banana peel and some AA batteries?

Most of you guys were here, way before any of us monkeys even existed. It just sucks to hand the monkey the coconut and then let him figure out where it came from/ how it got there/ where he can get more like it/ and how-in-the-hell he's going to open it?

Most of the monkeys are lazy. Unless you spoon-feed us the info, while drawing a detailed schematic in non-toxic crayola crayon, we just don't have a clue. Who the hell can fathom 1/4-wave acoustic resonance, kadency oscillation and thermal breathing... let alone a simple ballpark C:B ratio? Hell, I can't even figure out the math on how to lay out a truncated cone!

It doesn't hurt to eat ramen noodle, sharing info and then telling the world: "You can make this, but I can do it cheaper / faster and better, than you can". Trust me, most people are like the lazy monkey and even if you share all your knowledge, they STILL want you to do it for them.

I have one of those chintzy spot-welded pieces of crap, that Eric warns the consumer against buying. It was a gift, so I couldn't refuse. - The info on the injector diameter alone, was worth the money that was spent on the engine. And although HIS injector setup leaked-like-a-bitch and didn't work, I was able to make two injector out of 3/16" diameter steel brakeline that worked perfect.

My last (and most important) point, still remains- There are few people out there, that are willing to share their knowledge. If their knowledge is what makes them a living, then that's great for them. But I've asked before, for some specific FREE information, only to get the atypical "trial-and-error" scenario. It's cool... and that's exactly what I did.

[Rocket Man]

I feel your pain. It seems everyone here is flying by the seat of their pants. I have asked questions and I get answer that say, this question has been answered before do a search and you will find it. I have done searches and I have no idea what words to type in as a search so I never find what I want. Hours and hours of search finds nothing.

I have been building valved pulse jets for 38 years. I learned a lot by trial and error. Lots of testing to see what works best and keep good notes. I can build a valved pulse jet engine that will run for several hours with no damage to the reed valves and it is 85% throttable and will run on anything that burns. I have my own formulas I can design any size engine I want in about 10 minutes.

I am just now learning about valveless pulse jet engines. I want formulas to calculate and design my own engines but there doesn't seem to be any. So I am doing research and creating my own data. This seems to be the only way. I can't tell you much at the moment about valveless engines but I can tell you anything you want to know about valved engines. After doing several experements I can see that it won't be very hard to come up with some forumlas to calculate all the demensions of an engine the valveless is not a lot different than the valved engine. Like you said, just about anything will run but what we want is something that runs good and produces maximum thrust and maxiumum efficiency. I have watched 100s of videos too so far valveless engines seem to be noise makers that burn a lot of fuel and produce very little thrust compaired to valved engines.

[Kool]

So I am doing research and creating my own data

I don't really see a problem in it
I think it's only logical that you have to proceed to get your own investigations, furthermore I get a fantastic feeling when I've found another new(old) pulsejet report. After more than 100 + hours searching I'm gonna understand more and more of pulse jets. Sometimes it's just one post in a 30 pages topic which make it clear for me

[PyroJoe]

Here is a general explanation by Mike:

viewtopic.php?f=3&t=4833

"
Generally, "rules of thumb" that work pretty well (but start to break down the smaller you go:
CC volume to intake volume ratio, 4-5
Area sum of all exits (as they meet the CC) to CC area: .35-.45
Lengths are all over the map, but if you divide the motor into 7ths, a running config is intake 1/7, throat 2/7
Lengths are acoustic, but at this level need not be observed, however, if you want to account for it, the tail pipe and intake pipe are physically made .3 (exit ID) short.

There are infinite combos that work, some better than others! This'll get you in the game.
"

[PyroJoe]

One from Larry:

viewtopic.php?f=3&t=4143

"
Here's one way to design a valveless pulsejet:
Decide on a general shape you like - say a conical chamber, straight tailpipe and rear-facing "Chinese" style intake
Decide on a reasonable chamber diameter you can build
Decide on a length that you think seems adequate - at least 8 or 9 times the chamber diameter
Decide on a tailpipe diameter - say, half the chamber diameter
Decide on an intake diameter - a little smaller than the tailpipe should work
Set the chamber to about 1/3 the total engine length
Add an "end correction" to the tail end (about 1/3 the tailpipe diameter) - that's the "acoustic end point" and establishes the "acoustic length" from the front plate of the chamber
Divide the acoustic length by 3 - that should be the acoustic length from the front plate to the intake's acoustic end point
Divide the engine's acoustic length by 5 - that's the acoustic length of the intake pipe
Lay out the chamber and intake centerline on a scale drawing, and mark the intake's rear acoustic point - then go forward from that point 1/3 of the intake diameter, and mark that as the intake flare edge
Make the intake physical length equal to the intake acoustic length MINUS 2 x the intake end correction - mark a point this far FORWARD from the flare edge on the chamber cone - this will be the REAR edge of the port into the chamber
Using the scale drawing, design the rest of the layout of the intake pipe, intake port and transition "pipe" into the port

This will give you a basic "FWE-like" design that might actually run the first time. It will work on some other chamber shapes, as long as they are fairly conventional and of reasonable size. It will not work well for "odd" chamber shapes, like square boxes, etc. or with non-straight tailpipes.

The "intake path length = 1/3 full path length" relationship is what I named the "Hinote Criterion" after Bill Hinote suggested these proportions to me. After hearing that from him, I quickly designed my first successful engine, the "Short Lady" FWE. There is nothing "magic" about the 3:1 ratio Bill described - it was simply what he observed as being APPROXIMATELY correct for a variety of WORKING valveless designs he had actually seen (Thermojet, Chinese, etc.). It is what it is because it works with the engine temperatures we normally obtain in small pulsejets, that's all. It is nothing but a "place to start" - your mileage may vary.

Note that, if you're experimenting with a "different" chamber style or something, the final logical step would be to lengthen the tailpipe slightly, so you have something you can cut back gradually to tune your design. Once you try several designs, you gain more knowledge of the "little things" that make a difference, and your initial attempt at a design can improve - you are able to make better "educated guesses" at the beginning. And, of course, tools can be used to verify a design (but they always involve guesses, too, such as internal temperature layouts!).
"

[PyroJoe]

Chadly method for "Injector placement and design":

viewtopic.php?f=3&t=4730

"
With all my engines so far I have been able to start airless. From my big 18 litre CC to my tiny hip flask CC sizes. After playing with stinger types on my little one I was getting frustrated with not getting it to sustain so I threw my hands up in the air and welded the injector in just like my others! Surprise surprise it started straight away airless! So I thought I would share this little recipe with all hoping to help out. We all know that most of our intakes are three times as long as they are wide, well mark the intake 2/3 in from the open end and drill a hole the same size as your fuel(gas)pipe(injector) now cut with a suitable tool a small slit across this hole(this is to allow the squashed end of the tubing to slip through) I usually use a small flat blade screwdriver to open this up by levering down towards the open end of the intake this will also allow you to get the right angle on the injector! Now with the injector pipe I use a feeler guages that I have trimmed down to allow them to fit into the piping while I am sqashing them in the vise. file or sand the end of the pipe clean then place the tip into the vice only about the last 5 mm slowly start squashing the tube making sure that the feeler guage is in properly, squash till you cant squash no more! undo the vice and remove the feeler guage! I use 5 thou on my tiny engines, used 10 thou then went to 20 on my triple piper It worked out that about 10 thou per litre of cc ! bend the end and insert into the prepared hole so that the injector points towards the bottom inside end of the intake. I weld my steel lines in but only after fine tuning the injector should be a nice snug fit usually lightly tapped in but only so it makes slight ingress into the intake(to the unsquashed section) the feeler guage tuning allows me to start my engines straight off the bottle with no mixture screws. hope this info can help some people out there get their engines running airless it works on all mine ! will try to post some pics soon with complete step by step guide!

Cheers, Chadly.."


The three point propane injectors I use developed by GRIM have run engine sizes from 2.3" diameter all the way up to 6.75" diameter. I could probably use one injector and slowly crimp the end from engine to smaller engine and run the majority of my collection from one injector.

The above is just a small sampleing of what is available here.