jetZILLA - the Online Magazine of Amateur Jet Propulsion jetZILLA - the Online Magazine of Amateur Jet Propulsion jetZILLA - the Online Magazine of Amateur Jet Propulsion
Jan/Feb/March 2005 - Volume 2 Number 1

Think building your own jet engine is too costly and difficult? US high school student Steve Bukowsky built this engine for a few dollars and just a few hours in shop class ... it started and ran the first time he tried it, and it runs great on standard propane gas! See our Feature Article, below.
Steve Bukowsky's original prototype of Larry Cottrill's Focused Wave Valveless Pulsejet - photo (c) 2003 Cottrill Cyclodyne Corp.
Photo Copyright 2004 Steve Bukowsky
Unretouched photo of an early propane-fueled run of Steve Bukowsky's prototype build of Larry Cottrill's latest design - the Focused Wave Valveless Pulsejet Engine, code named 'Short Lady'. The engine is now under development to re-design the intake for liquid fuels, and to increase thrust and reduce overall weight to flight engine performance levels. Plans, kits and finished engines are planned for market in the spring of 2005. See the Feature Article in this issue.

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jetZILLA   JAN / FEB / MAR   2 0 0 5   E D I T I O N  -

jetZILLA Online Magazine of Amateur Jet Propulsion Development
    © 2003 Cottrill Cyclodyne Corporation
       [a free subscription e-magazine]
Issue 2005-0320-0201-00                       March 20, 2005
Approx. circulation: 160 world-wide
Publisher:  Larry Cottrill, Cottrill Cyclodyne Corporation, 
                Mingo, Iowa  USA   50168-9500
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Welcome, everyone!

I N   T H I S   I S S U E . . .
   The Soul of a New Machine - 
   Designing, Building and running 'The Short Lady'
   Focused Wave Valveless Pulsejet Engine
   by Larry Cottrill

   Eric Beck's Pulsejet Calculator  
   - Version 1.4 [August, 2003] - download link!
   by Eric Beck

   Exciting International Year of the Valveless Pulsejet 
   mini-posters now available!
   by Larry Cottrill

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 F E A T U R E   A R T I C L E . . .
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The Soul of a New Machine -
   Designing, Building and Running 'The Short Lady'
   Focused Wave Valveless Pulsejet Engine
   by Larry Cottrill


In the summer of 2004, I managed to design, build and run my first
successful pulsejet, a crude valveless design I called Elektra I 
[since it was cheaply built entirely out of ordinary rigid 
electrical conduit]. This design was duplicated by high school 
student Steve Bukowsky of Connecticut, USA, also with good success 
[Steve already had some pulsejet building experience with valved 
designs]. The story of the Elektra I can be seen at the Elektra I 
Builders' Web Log, The length and 
proportions of this engine were awkward, however [the design had 
to be lengthened to 39 inches - almost a full metre - to sustain 

A couple of things happened at about this time on Kenneth Moller's 
Valveless Pulsejet Forum that changed my ideas about valveless 
engine design: First, Australian jet builder Ross Gordon had done 
some experimenting with shoving intake pipes into the combustion 
chamber to varying depths, and observed that there is a kind of 
'sweet spot' for the inner end of the pipe, where the breathing of 
the engine seems optimal. Second, an American experimenter, Bill 
Hinote, mentioned his interesting observation  that several 
successful valveless engine designs with rear-facing intakes 
seemed to have a couple of proportions in common; namely, that 
these closed-end designs have intake ducts that were almost 
exactly 1/5 the total engine length, and seemed positioned in such 
a way that the intake opening ended up at almost exactly the 1/3 
length point from the front end plate of the engine! [I found this 
fascinating, and decided that these proportions should be called 
'The Hinote Criteria' for this class of valveless jets.]

I now felt I had to carry this farther. It seemed to me that the 
most critical point in such a design was the point at which the 
intake pipe opens into the main wave path, a point which we on the 
forum eventually came to call the 'Reynst Point' [i.e. the point 
where the low pressure wave of the engine is ideally applied to 
make the engine breathe for the next pulse]. I pointed out that, 
in the case of an engine where the Hinote Criteria apply, this 
point is very nearly at the L/8 point of the engine length [where 
we call the full pipe length L, by convention]. 

I then hypothesized that any engine closed at the front should 
breathe at the L/8 Reynst Point, if provided with an approximately 
L/5 intake pipe that enters the wave path at that point, from any 
direction. [It turns out that this isn't quite true for every 
closed-end design; but it may be true for engines where the main 
tube is a more-or-less straight pipe from nose to tail.] So, the 
relationship of the three fractional dimensions would look 
something like this:
The Hinote Criteria and the Reynst Point. Drawing Copyright 2004 Larry Cottrill
A Simple Engine from a Simple Theory I had felt for a while that the traditonal 'flashlight shaped' tailpipe design, while good at providing high velocity exhaust gas ejection, had the inherent flaw that much of the blast energy of the explosion was wasted in high frequency 'standing waves' that keep vibrating in the chamber after the main wave has moved rearward. I believed that the simplest, most effective design would be a shallow domed front end where the explosion would take place, followed immediately by a long conical chamber 'focusing' the blast wave into the front of the tailpipe. I call this concept the 'focused wave pulsejet engine', which became [unfortunately] immediately abbreviated to 'focused wave engine' or FWE. [I say 'unfortunately' because this makes it sound like a 'wave engine', which it is not - this IS a pulsejet in the truest sense of the word.] I used the software tool UFLOW1D to design the chamber. To my amusement, eliminating the high-frequency 'ringing' in the chamber involved an even longer cone than I had imagined, with a very long side slope - the cone takes up almost ONE THIRD of the total engine length! However, this produced very good wave shape and travel, both for the blast wave and suction wave, even in an engine as short as 26 inches! This is very unusual in a valveless design; hence, the code name 'Short Lady'. Here's the original drawing as posted to Kenneth Moller's Valveless Pulsejet Forum:
The original Focused Wave Pulsejet Engine drawing. Copyright 2004 Larry Cottrill
Original Prototype Build: Steve Bukowsky Strangely, having designed the engine, I now felt that I didn't have adequate facilities to build the prototype! [I've never had to roll my own sheet steel cones, and have no equipment to make nice work of them.] Fortunately, Steve Bukowsky, a young member of the forums, really liked the design and immediately offered to build the prototype! Since he had access to his school shop facilities and needed a project to work on, I naturally readily agreed, realizing that this would probably be the shortest path to seeing the engine actually built and tested. The original Focused Wave Engine prototype, as built and run by Steve Bukowsky (c) 2004 Steve Bukowsky Steve Bukowsky's original 'Short Lady' build, running "full grease" on propane vapor fuel - exhaust ejection from the rear-facing intake can be clearly seen in this photo. Steve's 'Short Lady' started and ran on the very first try! Photo Copyright 2004 Steve Bukowsky Jet experimenter Steve Bukowsky (c) 2004 Larry Cottrill Jet experimenter Steve Bukowsky Photo Copyright 2004 Larry Cottrill My First [Second Prototype] Build of the 'Short Lady', in Pictures Since Steve had obviously done such a beautiful job of fabricating the cones in his school shop, I negotiated with him to make two sets of cones for me, at a very reasonable price. Here is Steve's shot of the combustion chamber parts as he was working on them for me, alongside his finished 'Short Lady' engine. Note that the wall cones are fully formed and tack welded in this shot; the front end cones [which I call "domes"] are cut but not yet rolled and tacked [he did that as well, before shipping them to me]: Steve Bukowsky's finished engine alonside the combustion chamber parts he made for me - Photo (c) 2004 Steve Bukowsky Photo Copyright 2004 Steve Bukowsky Here's the combustion chamber wall cone, right after I finished the side seam welding: One combustion chamber wall cone, with the side seam finish welded (c) 2004 Larry Cottrill And here it is welded up to the 'antenna mast' tailpipe. The finish weld is reasonably reinforced, smooth inside and out, and holds the chamber in near-perfect alignment with the tube [internal smoothness is the critical issue here; any slight error in alignment is of little consequence]: Finish weld joining the combustion chamber cone to the tailpipe tube (c) 2004 Larry Cottrill Here's the finished front end dome with the spark plug mount welded in place, with a second dome in the background, waiting to be finished up in the same way: Finished front dome with spark plug mount fully welded in (c) 2004 Larry Cottrill Steve followed my design exactly, using 3/4-inch EMT [rigid electrical conduit] to built his intake tube and flattening the lower end slightly. His testing indicated that the intake drag was extremely low, possibly not a good thing for performance. Based on Steve's experience, I felt I could try reducing the intake to 1/2-inch EMT, leaving the tube round. The hole is formed by drilling and filing, trying to get the exact location and fit: Fitting the intake tube into the combustion chamber wall at the precise design location - Photo (c) 2004 Larry Cottrill Another difference in our methods: I wanted to mount the intake tube before welding on the front dome, for the sake of checking the tube alignment. I jigged the intake for tack welding by using a 5/16-inch bolt and nut and an old C-clamp: Jigging the intake to the chamber cone with a bolt, nut and C-clamp - Photo (c) 2004 Larry Cottrill I wanted engine mount lugs identical to the ones on my Elektra(TM) engines. Two identical engine mounts are cut from a single hardware store item called a 'fence rail bracket'. After this, the existing holes are drilled out to fit 1/4-inch mounting bolts. Cutting the engine mount lugs from a standard hardware fence bracket (c) 2004 Larry Cottrill These are temporarily bolted down to a flat piece of metal through properly spaced holes, then bent inward to meet the underside of the tailpipe, and tack welded in place [located right under the balance point of the engine]. Then, they're unbolted and finish welded onto the tailpipe. The final weld of the entire project - getting the front dome welded on, mostly by just melting the edges together: Welding the front end dome onto the combustion chamber cone (c) 2004 Larry Cottrill The finish welded front end dome of the chamber, seen here with the spark plug temporarily threaded into place: Finish welded front end dome, with spark plug in place (c) 2004 Larry Cottrill Closeup of the finished front end, seen from the left rear. In this view, the intake weld, cone-to-tailpipe weld and engine mount weld are all clearly seen: Finished engine front end closeup (c) 2004 Larry Cottrill The finished engine mounted on a flat wood plank, about 3/4 inch thick and about 6 inches wide. The best heat shielding material is sheet aluminum, which is light, cheap and very easy to work with. The bolts I used are short, large head 1/4-inch aluminum bolts; 1/4-20 'tee nuts' are driven into the holes from the bottom side of the board. The result is an engine and test mount assembly that can be easily handled and clamped down to something heavy when needed: The engine mounted for testing on a simple wood plank mount, with sheet aluminum heat shielding in place (c) 2004 Larry Cottrill My starting rig is nothing but a high voltage spark coil, propane supply and a shop vac rigged as a blower. Once she starts, you just shut off the air and spark and sit back and enjoy the roar of the 'Short Lady' Focused Wave Valveless Pulsejet - note the front end getting good and hot after just a few seconds of running: The Focused Wave Valveless Pulsejet, running on its own and starting to get hot (c) 2004 Larry Cottrill It should be able to run as long as you want [or until the propane cylinder 'freezes up' from the internal pressure drop] - just shut the fuel off at the needle valve to stop it. Steve's 'Short Lady' Photo Gallery During the summer of 2004, Connecticut high school student Steve Bukowski decided to build a working prototype of my "five dollar valveless pulsejet", the Elektra I, which I had just designed, built and successfully run. Steve built his in just a few hours, and got it running with little difficulty. Here's Steve's parody of my 'What every man needs is a jet to fly' promotional shot, featuring the Elektra I [yes, that thing under his hand is the engine!]: Steve Bukowski with his hand-built Elektra I prototype (c) 2004 Steve Bukowsky Poster Copyright 2004 Steve Bukowsky After school started at the end of summer, Steve was looking for a more challenging pulsejet project, since he once again had access to his school's metal shop equipment. So, when I announced a new design, the 'Short Lady', on Kenneth Moller's Valveless Pulsejet Forum, Steve asked if he could be the first one to try to build one. Since I had no way of rolling the sheet steel cones, I was happy to have him give it a go. Since Steve built [and ran!] the world's first prototype of the Focused Wave engine, he was able to get the first photos of it, including some fine shots of it running in almost total darkness. Some of these lose a lot due to size reduction for this page, unfortunately, but they still give a good idea of the drama of building and running the 'Short Lady': Steve's test mount - he doesn't like welded-on mounting lugs, so he just held it with metal brackets at the spark plug and the tailpipe: Steve's 'Short Lady' engine on his test mount (c) 2004 Steve Bukowsky Photo Copyright 2004 Steve Bukowsky Top view from the front and a rear view from up close: Running top view from the front (c) 2004 Steve Bukowsky Running rear view from up close (c) 2004 Steve Bukowsky
Both photos Copyright 2004 Steve Bukowsky
A nice view of the combustion chamber: A nice view of the combustion chamber (c) 2004 Steve Bukowsky Photo Copyright 2004 Steve Bukowsky Good top view showing flame ejection from the rear-facing intake: Good top view showing flame ejection from the rear-facing intake (c) 2004 Steve Bukowsky Photo Copyright 2004 Steve Bukowsky Steve's homebuilt rig for thrust measurement, using precision lab scale on loan from school: Steve's homebuilt rig for thrust measurement, using precision lab scale on loan from school (c) 2004 Steve Bukowsky Photo Copyright 2004 Steve Bukowsky Another shot of the thrust measurement rig, showing the entire test equipment setup - starting air [he used a compressor and hand-held valve], propane supply and ignition system: Another shot of the thrust measurement setup, showing the entire test equipment setup - starting air, ignition system, propane supply (c) 2004 Steve Bukowsky Photo Copyright 2004 Steve Bukowsky _____________________________________________________ Photo Credits: All photos in this article were provided by, and are property of, the author or Mr Steve Bukowski [used by permission]. _____________________________________________________ Larry Cottrill is a pulsejet designer, builder and experimenter and Editor of jetZILLA ezine, living in the State of Iowa, USA. To contact him about this article, email: _____________________________________________________


 -   S P E C I A L   F E A T U R E   -
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Eric Beck's Pulsejet Calculator
- Version 1.4 [August, 2003] -
by Eric Beck

Note from the Editor:
Eric's Pulsejet Calculator is probably one of the most useful
tools ever offered to the amateur experimenter. It allows quick
and easy calculation of all critical dimensions, including the 
cutting patterns for cone sheets. We are proud to offer Eric's 
complete description and instructions for use of the program, as 
well as our own link for downloading your copy, at no cost. The 
program is actually an XLS [Excel spreadsheet] file, so you'll 
need MS ExcelTM installed to use it.

Here's what is unique about Eric's program: Several pulsejet 
design programs have been developed based on theory - they 
usually only work acceptably for engines of fairly large size. 
Eric's spreadsheet formulae are based not on strict theory, but 
rather on his own observations of the design of successfully 
tested valved pulsejets that have been developed over the years 
in a wide variety of sizes and three distinct valve designs. His 
method tends to produce tailpipe designs that are reasonably 
proportioned and buildable for all practical sizes of valved 
engines [as Eric mentions in his article, there are some special 
considerations that need to be understood in getting extremely 
small pulsejets to work].

While we believe that operation of the program is correct, and 
that it should consistently yield satisfactory results, the 
author takes complete and sole responsibility for support of 
this program. 

We hope you'll enjoy using this unique design tool!

- Larry Cottrill, Editor



A pulsejet engine is one of the most fascinating types of engines 
I have ever encountered. The pulsejet is mechanically very 
simple, but the physics behind how a pulsejet works is 
intriguingly complex. Pulsejets can be used to power a variety of
different types of vehicles ranging from planes to go-karts. 
Because pulsejets are so simple to make compared to gas turbines,
amateurs and hobbyists often choose to build them when they want
jet power. This is where people can run into problems. Although 
just copying a proven design is easy, designing and building your
own pulsejet engine can be extremely difficult if you do not know
where to start. Often people can be discouraged by a poor engine 
design and decide to quit working on it altogether. 

Over the past several years, I have been studying pulsejet 
engines in detail. I have designed and built several engines and 
many things to improve their performance. I have studied every 
aspect about every working pulsejet design I have found. I have 
also read much literature about the history of this type of 
engine, and about previous studies of the pulsejet engine. I was
searching to find some type of law or equation that governed a 
pulsejet engine's dimensions. With the data I gathered, I hoped 
to one day make a program that would help people be able to 
design their own valved pulsejet engine.   

Shortly after writing my book on pulsejet engines (which I hope 
to release soon), How to Design and Build an Advanced Pulsejet 
Engine, I decided to sum up many of the equations into one excel 
program so that the dimensions for any size pulsejet engine 
could be calculated almost instantly. 

I decided to have the program focus on the design of the 
tailpipe of the engine. The tailpipe design is crucial to the 
operation of the engine and is so commonly out of proportion in 
the average home-designed engines. The dimensions generated by 
this program are extremely accurate and have very high 
correlation with well-designed real world engines. By simply 
entering the thrust you want the engine to produce, every aspect 
of the tailpipe dimensions are generated. The estimated frequency
that the engine will operate is also on this page. In the next 
version I hope to add a page to calculate all other dimensions 
such as fuel system, valve head, and the valves. 

What people must understand is while the dimensions generated for 
a very small pulsejet (under 2 pounds thrust) are accurate to 
theoretical values, they still may not run with ease. The smaller 
a pulsejet engine is, the more precise every aspect of the 
pulsejet engine's construction and operation must be. It is also 
difficult to get fuel to mix properly in a small engine, and 
variations in atmospheric pressure and temperature will have more 
of an effect on a smaller engine. These are all things that cause 
small engines to be difficult to run. A small engine is not 
recommended for a beginner’s first engine. 

Early versions of my program only calculated the basic dimensions 
of the engine. My new release Pulsejet Calculator V1.4 is a major 
improvement over previous versions. Each part of the program is on
a different page, all contained in one Excel spreadsheet. Before 
going into how to use the program in detail, I will briefly 
summarize the basic functions of the program.

There is a brief introduction to pulsejet engines and the three 
types of valve systems commonly used. Pulsejet calculator 1.4 not 
only incorporates the improved dimension calculator page, but also
can give the flat sheet metal projection for all the parts of the 
tailpipe. The dimensions and layouts are created in both English 
and metric units for all three tailpipes needed to contain a valve
system to produce a specific thrust.

The flat pattern projection dimensions created on the sheet metal 
layout page is a major help to people who want to roll the engine 
out of sheet metal. The cone section dimensions are normally hard 
to calculate by hand for each different cone, and very few people 
actually make their cone flat patterns to the right dimensions for
this reason. The sheet metal layout page also allows you to 
calculate the weight of your pulsejet engine tailpipe by simply 
entering the thickness of the metal being used (sheet metal gauge 
chart included for reference), and by entering the density of some
suitable alloys (you can choose from a list or enter your own). 

The last page of the program allows you to generate the dimensions
of an exhaust cone or single cone augmenter. To generate the 
dimensions of the cone, enter data such as large and small 
diameters, and length of the cone. The weight calculator is also 
incorporated into this page. The next part on the augmenter and 
cone creator page supplies dimensions to make your own dual cone 
augmenter tube. The only data needed is intake diameter, intake 
length, throat diameter, exhaust length, and exhaust diameter. A 
short explanation of how to make the cone section and how to design
the augmenter is also included in this page.

Obtaining the Pulsejet Calculator Program

Pulsejet Calculator 1.4 is a free program, and can be used and 
freely distributed as long as it is not modified and it is kept in 
its entirety. Before I give step by step instructions 'right click'
on the following link to download the program, and use the 'Save 
Target As' option to save it where you want to keep it:
Download Pulsejet Calculator v 1.4 now! 

Directions for Using the Program [with screen samples]

Once you have the program downloaded, you can go ahead and try it 
out. You should first read the introduction page, as it will explain
the three types of valve systems commonly used in pulsejet engines 
(petal valve, high efficiency petal valve, and valve grid). 

Pulsejet Calculator 1.4 creates a set of tailpipe dimensions that 
will allow you to use the three valve system types, as some types 
require a larger combustion chamber due to inefficiency. Each set 
of dimensions for the three valve types will produce an equal amount
of thrust; however, each type has some advantages over the other 
types. It is up to you to decide what type of valve system is right 
for you, and right for the size engine you will want to make. 

The basic tailpipe dimensions the calculator will provide are 
illustrated in this simple drawing, reduced here from the top of 
Page 1 of the spreadsheet:
Basic dimension layout of a valved pulsejet tailpipe, from Page 1 of Eric Beck's Pulsejet Calculator
Now all you have to do is enter in how much thrust you want from the engine in the “thrust cell” on the spreadsheet. Once you have entered the thrust you want the engine to produce, hit Enter and all dimensions will be calculated. Each part of the engine's tailpipe has been assigned a letter that corresponds to the letters on the tailpipe diagram. For those of you who are interested in what the engine's operational frequency will be, but are not sure how to figure it out, the operational frequency range will also be calculated. Here's what happens when we enter a thrust of 4.75 pounds [the dimension results are in inches; on the real spreadsheet, a separate column is provided for kg thrust and cm dimensions]:
Basic dimensions of a valved pulsejet tailpipe, from Page 1 of Eric Beck's Pulsejet Calculator
[Note: The input is about the thrust of the classic Dynajet engine. The calculated dimensions come up with a length of just over 19 inches, a chamber diameter of about 2.5 inches and a chamber length of almost 4 inches, with a tailpipe diameter of almost 1.25 inches - the actual Dynajet tailpipe is modeled almost exactly. The only essential difference is the conical nozzle section, as contrasted with the rounded nozzle form in the Dynajet, a detail that would have no noticeable affect on performance. - Editor] You can now move on to the next page or print the current page out. You can also save the file and all dimensions will be saved so you can view them later. For best results when printing, have your printer's setting on the highest quality. You now know the dimensions of the engine's tailpipe; now you want to figure out the dimensions of the sheet metal pieces you will need to roll the tailpipe (Note: With small engines it may only be possible to make the engine out of prefabricated tubing, but often odd sizes are needed and for larger sizes rolling from sheet metal will definitely be necessary.) Figuring out the dimensions of the sheet metal pieces is quite easy (with exception of the cone section), yet calculating them by hand is very time consuming. With Pulsejet Calculator 1.4 they are generated automatically as soon as you enter how much thrust you want. Here is the notation used in the spreadsheet for the sheet dimensions:
Basic sheet metal dimension layout for the valved pulsejet tailpipe, from Eric Beck's Pulsejet Calculator
At the bottom of the Excel page you will see tabs with the name of each page on them. Since we've already entered the thrust on the first page, we just click on the corresponding “Layout” tab. Again, we'll choose English units, by clicking the English Layout tab. We see the sheet dimensions on the spreadsheet page [this sample is from the left side of the page - the sheet dimensions C1 and C2 for the long straight pipe section would appear on the right side of this page in the real program -Ed.]:
Basic sheet metal dimension layout for the valved pulsejet tailpipe, from Eric Beck's Pulsejet Calculator
Once again, dimensions are generated for each of the three valve systems including the dimensions of the nozzle cone section. Note how all three sets of dimensions are clearly shown on the sample page. Finding the dimensions of the cone section can be difficult for some, and time consuming to work out by hand. Previously, If you wanted to have the cone section calculated by a program the cone section would have had to be calculated by a separate program such as the well-known Cone program. With Pulsejet Calculator 1.4 all the dimensions are created for you all in one step, which reduces the hassle you would need to go through with downloading and running separate programs to get the full set of dimensions you need. The mass properties section will allow you to calculate the weight of your tailpipe. Enter the sheet metal thickness you will use for the engine, and then enter the density of the metal you will use (you may choose from the reference list or use your own). Once you have done this, hit enter and the weight of all three tailpipes will be calculated. This page can be printed for reference, or you can move to the custom cone and augmenter page if you wish. This sample is from the upper right- hand side of the page, showing this section:
Basic sheet metal dimension layout for the valved pulsejet tailpipe, from Eric Beck's Pulsejet Calculator
The final page will help you generate the dimensions of your own custom sized exhaust cone, or augmenter tube. There is a brief introduction to rolling cones and designing augmenters on this page. Both parts include the mass property calculator, and can be used much in the same way as on the previous page. As already shown, it only takes two dimensions and an angle to specify the sheet of a cone - this page labels them as follows [in the left- hand drawing]:
Basic dimension layout for a cone sheet, from Eric Beck's Pulsejet Calculator
The drawing on the right shows the basic plan for a simple thrust augmentor made up of two cones welded together. [Note: For those who aren't familiar with pulsejet lore, an augmentor is a kind of 'special purpose venturi' placed in the hot exhaust stream. Its sole purpose is to capture cool air from around the engine and mix it with the hot gases in the exhaust stream to increase the stream mass in order to develop extra thrust force. If properly designed, this can be shown to increase thrust significantly at low forward engine speeds, though it seems to be much less effective as speed increases. - Editor] This page is different from the others; there is only one place to enter the finished plan dimensions of your cone or augmenter. Enter the plan dimensions in Inches or Centimeters. The sheet dimensions will be generated. To use the weight calculator, enter the properties in the area that corresponds to the units you used to calculate the dimensions. The weight / mass will be generated in both kinds of units automatically. Here's an sample screen [input in centimeters, this time!] showing a long combustion chamber cone and a small augmentor - this time, we ignore the calculated weight in pounds, since we're working this example in metric units:
Calculation of a cone and a bi-cone augmentor, from Eric Beck's Pulsejet Calculator
You will notice that if you enter the units in inches, the weight in kilograms will not convert to the same weight in pounds. This is because the metric portion of the calculator will treat the dimensions as if they were in centimeters, where the English part will treat the dimensions as if they were in Inches. So - you must use only the output data field that is consistent with your input units - if you input inches, you will read the results in the Weight in Pounds field; if centimeters [as in this example], you would use the Weight in Kilograms field. So, for both sections, you can follow the directions to make a proportional augmenter or simply design your own. Conclusion Now that you have a basic understanding of all the functions of this program, you should be able to easily design the most important part of your pulsejet engine - the tailpipe - as well as lay out any other sheet metal cones you may need and simple experimental augmentors that will be easy to build. ____________________________________________________________ Eric Beck is a student in the US. About himself, Eric wrote the following [written in August 2003]: "A little about who I am (probably going to shock a few people) - I tend not to tell people I talk to online how old I am because of my previous experiences with DIY forums. As soon as I told them, they either acted like I didn’t know what I was talking about, didn’t take me seriously, or ignored me altogether. I have always had an interest in building things. I first started gathering all the necessary equipment that I could afford for my machine shop when I was 15. I built my first pulsejet engine from the basic plans posted on Bruce Simpson's site in preparation for my plans to use it as a school project. The engine did not run in any way even after a second prototype was built. When I was 16 I had to do a project for physics class and while everyone else was off writing 3-5 page papers I was building a 'Dynajet clone' engine plus the 5 page paper. The rugged monster started up right away. Ever since, I have been obsessed with pulsejets and read everything I can find on them. I am only 17 right now, and in September I am going off to Penn State University for aerospace engineering." Eric is justly famous for his beautiful CAD renderings of existing pulsejet designs. You can see many of these on his pulsejet pages: Eric's Pulsejet Home Page Pulsejet CAD Renderings ____________________________________________________________


 -   P R O D U C T   I N T R O D U C T I O N   -

Note - The following article features our own products, and should be 
       construed as advertising or promoting those products
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Exciting International Year of the Valveless Pulsejet
mini-posters now available!
by Larry Cottrill
The Posters

Digital mini-poster: Focused Wave Valveless Pulsejet Closeup - image Copyright 2004 Cottrill Cyclodyne Corporation
As a member in good standing of Kenneth Moller's forums, and as editor of jetZILLA Online Magazine, I decided that we needed to do something special to celebrate the year 2004 - to announce to the world that this was the year that people of differing interests, skills and nationalities had produced innovative valveless pulsejet designs that are easy to build and really run! Since we all take pictures of our creations in action, I decided, what better way than to create a series of colorful mini-posters to commemorate our 'International Year of the Valveless Pulsejet'? I offered to produce the posters and contribute $1.00 US to the Website from the proceeds of every poster sold.
Digital mini-poster: Focused Wave Valveless Pulsejet Closeup - image Copyright 2004 Cottrill Cyclodyne Corporation
What You Get

Posters are printed on heavy weight, bright white, acid-free paper, 11 x 17 inches [about 28 x 43 cm] outside dimensions. Some are 'portrait' format [vertical] and some are 'landscape' format [horizontal]. Posters are signed by Larry Cottrill and hand-numbered on the white border, and are strictly limited editions. All payments are through PayPal, and if you don't have a PayPal account, you can choose to pay through any common credit card when you order. Posters make great gifts, and there are no additional S & H charges on multiple copies of the same poster!
Digital mini-poster: Focused Wave Valveless Pulsejet Closeup - image Copyright 2004 Cottrill Cyclodyne Corporation
NOTE that these are processed from digital images provided by the engine creators - you WILL see pixels visible on close inspection. The posters are guaranteed to look beautiful when seen from a normal viewing distance of about 25 inches [approx. 70 cm]. Sorry, larger prints are not available.
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To see the entire Year of the Valveless Pulsejet poster series, to get all the details on prices, payment, shipping and handling, or to place your order immediately, go to our sales page now:
Year of the Valveless Pulsejet - posters sales page

"To God Alone be the Glory"
- Johann Sebastian Bach 1685 - 1750

P R O D U C T S   A N D   S T U F F  . . .
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V i s i t   O u r   F r i e n d s  . . .

   Bruce Tharpe Engineering - 8622 E Evans Creek Road, 
      Rogue River, OR 97537  Phone: 541-582-1708. 
      Assembled fuel bladders, pulsejet model plans and 
      MUCH more.   email:

   ModelFlight - United Kingdom 
      A top-notch magazine for model flyers -- check out 
      the 'Gallery' section for photos of some absolutely 
      beautiful aeromodeling work from all over. Lots of 
      scale stuff. Good construction hints, reviews, etc. 
      All kinds of aeromodeling represented, including the 
      occasional jet craft.    

V i s i t   O u r   O w n   L i n k s  . . .

   Reynstodyne FokusTM Valveless Pulsejet Engine Design / 
     Development Page - the world-famous"Short Lady"    

   Year of the Valveless Pulsejet poster series -
     see the full selection of mini-posters, get all the details 
     on pricing, or place your order immediately via PayPal

   Reynstodyne Elektra ITM Valveless Pulsejet Engine Design / 
     Development Page - the original "Five Dollar Valveless 

   Maggie MuggsTM Low-Speed Ramjet Engine Design / 
     Development Page - the original "No Weld Ramjet"    

   Cottrill Cyclodyne SFOATM Pulsejet Engine Design / 
     Development Page - where "Steel Floats On Air"    

   Tools for Marketers / Webmasters [ TfMW ] -
     Page 2 [ complete product catalog ] -    

   Cottrill Cyclodyne Corporation Site Directory -    

   jetZILLA Initial Press Release [ return to the 
      jetZILLA home page, then select from 'Archived 
      Editions' ] -    

M a k i n g   M o n e y   o n   t h e   'N e t  . . .

   Super Affiliate Handbook - 
      Fact:   The vast majority of Affiliate Marketers will net 
              exactly ZERO dollars this year.
      Fact:   Rosalind Gardner earned  OVER $436,000 HER 
              FIRST YEAR selling other people's stuff online 
              ... and she can prove it!    
      packed with solid information, how-to tips, pitfalls you 
      MUST avoid, the HOWs and WHYs of affiliate marketing and 
      MUCH MORE -- and, it's backed with the publisher's own 
      90-Day No-Questions-Asked Full Satisfaction Guarantee.
      Super Affiliate Handbook    

   Push Button Publishing - 
      Bryan Winters promises: "Not Only Will I Show You
      How to Make Your Living Online, I'll Also Pay For
      the Products, Services, and Resources Needed to 
      do it: Web hosting, Autoresponders, Ad Tracking, 
      and More!" Click here for the solution you've been 
      searching for: Push Button Publishing    

A L L   T H A T   B O I L E R P L A T E . . .
Contents   Top   Subscribe Now
T h e   W e b   E d i t i o n  . . .
If you're reading the email version of this newsletter, 
you may find the Web version much more enjoyable. It is 
prettier, and you don't have to click on the pictures to 
view them! Go to and click on the 'Current Edition' link. We also provide a link for Web pages archiving past issues. _________________________________________________________ D o n ' t T r y ' R e p l y ' . . . (email version) _________________________________________________________ Like virtually all newsletters/ezines on the 'net today, jetZILLA is mailed via an autoresponder - using your 'Reply' button will just result in 'bounced' (nondeliverable) email. Please use the Subscribe / Unsubscribe / Change / Contact information detailed below. _______________________________________________ W h o I n t h e W o r l d A r e W e ? _______________________________________________
  Larry Cottrill with Reynstodyne(TM) Shark(TM) engine prototype after early test firing - Photo Copyright 2003 Cottrill Cyclodyne Corporation
  Larry Cottrill with ReynstodyneTM SharkTM engine prototype after early test firing
Photo Copyright 2003 Cottrill Cyclodyne Corporation
My name is Larry Cottrill. I'm Director of Product Development and Acting CEO of Cottrill Cyclodyne Corporation, registered as a for-profit corporation in the State of Iowa, USA. We are striving to create the world's smallest, safest and most practical hobby jet engines. We also have an intense interest in Internet- and Web-based marketing [since our future products will be promoted and marketed extensively online] and offer top-quality, low-cost and no-cost resources to help make the jobs of marketers and webmasters easier, more cost-effective and more productive. ________________________________ T h i s N e w s l e t t e r a n d Y o u (email version) ________________________________ You are receiving this free issue because of one of the following: -You specifically elected to subscribe from one of our Web pages -I know you personally and thought you'd like it -I asked you if I could send it and you agreed to try it -Online, you recently expressed interest in receiving information related to miniature jet propulsion systems -Someone you know forwarded it to you because they believed you'd enjoy it or benefit from it [see subscription instructions below]. If you don't want to receive future issues, scroll to the bottom for unsubscribe instructions. You are free to unsubscribe at any time in the future, of course. Our goal is a monthly newsletter that will: -help you enjoy the miniature jet engine hobby -share articles and other resources of interest -be easy to read and truly informative -answer specific questions asked by our readers Your email address is the ENTIRE CONTENT of our database listing for you. NO FURTHER DATA IS ON FILE, AND YOUR SUBSCRIBER INFORMATION IS NEVER SHARED IN ANY MANNER FOR ANY PURPOSE. PERIOD. All related mailings from us will ALWAYS be clearly identified with the jetZILLA brand name/trademark. _______________________________________________ F r e q u e n c y o f P u b l i c a t i o n _______________________________________________ Our newsletter is sent/updated approximately once per month, except for RARE instances of non-commercial 'public service' information that we feel is of an urgent nature warranting a 'Special Edition'. ___________________________________________ C o m m e n t s a n d Q u e s t i o n s ___________________________________________ Comments, reader questions and suggestions are always welcome! You are free to contact us at any time: email: We will do our best to respond within 48 hours, at most. We reserve the right to publish questions and answers if we think they would be of interest to other readers - if you don't want your name published, please type 'Withhold Name' at the top of your question. We will NEVER publish your email address, unless you include it yourself in a BRIEF 'signature' block beneath your name at the bottom of your email text. ________________________________________________ H o w t o S u b s c r i b e (email version) ________________________________________________ Just use this link for your subscribe request: and click on one of the links to create a 'subscribe' email. You do not need to fill in the Subject line or include any text. Be sure you do this FROM THE EMAIL ACCOUNT WHERE YOU WANT TO RECEIVE each email issue of jetZILLA ezine. ________________________________________________ H o w to C h a n g e Y o u r S u b s c r i b e r D a t a (email version) ________________________________________________ It's easy to change your subscription data - just use the following procedure: A. Unsubscribe, using the link at the BOTTOM of this email. B. GO TO THE EMAIL ACCOUNT WHERE YOU WANT TO RECEIVE jetZILLA ezine, and use the ‘Subscribe’ link (same as above): It is not necessary to include text in the body or Subject. ____________________________________________________ H o w t o U n s u b s c r i b e (email version) ____________________________________________________ We're sorry to see you go! But, we realize that people's needs change, and not every publication can be beneficial to every possible subscriber. We hope you've enjoyed being with us and that you've benefited in some way by receiving jetZILLA ezine. Just click on the Unsubscribe link at the bottom of this email. You should receive an acknowledgement email very soon thereafter. Thank you! - Larry Cottrill, publisher jetZILLA ezine

Page updated: 17 March 2003

Copyright 2003 Cottrill Cyclodyne Corporation
- All rights reserved -