jetZILLA TM quasi-monthly magazine
The family-friendly online magazine of MINIATURE JET PROPULSION!
- April/May 2003 - Volume 1 Number 3 -

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Valve plate / fuel inlet assembly by Mark 'Thixis' (c) 2003 Cottrill Cyclodyne Corp.   PULSEJET  TECHNOLOGY

  Valve plate / fuel inlet
  assembly designed and
  built by Mark 'Thixis'
  [our interview with Mark
  appears in Part 2 of
  this month's Feature
  Article, below]. In this
  view, we've drawn in
  an idealized venturi as
  it would be used, and
  annotated the basic
  elements of this
  interesting built-up
Photo Copyright 2002 Cottrill Cyclodyne Corp.

jetZILLA  A P R I L / M A Y   2 0  0 3   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 2003-0508-0103-00                       May 8, 2003
Approx. circulation: Unknown
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 . . .
   Real Jets, Real Cheap - 
   20th Century technology on a 19th Century budget
   - Part I 
   - Part II
   Interviews with Mike Kirney and Mark Thixis

2. VERY SPECIAL OFFER! From a friend of jetZILLA ...
   Get Your Copy of Original Lockwood Research Paper 
   - a 'must have' for valveless pulsejet hobbyists!
   offer by Ben Brockert

   Proposed design for Reciprocating Valveless Pulsejet Engine 
   by Larry Cottrill

   Products, links, ads, etc...

   > Metals in Pulsejet Interiors -
     Destructive Tests Reveal the Truth!

   Who we are, Subscribe, Unsubscribe, Privacy, etc...


 F E A T U R E   A R T I C L E  [t w o   p a r t s] . . .
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Real Jets, Real Cheap - 
   20th Century technology on a 19th Century budget 
   [Part I]
   Interview with 'Tundra Man'

Note from the Editor:

Many hobbyists are first attracted to pulsejets because of their 
seemingly cheap and simple construction.  These people are then 
shocked when they peruse the Web and find jets on E-Bay costing 
hundreds of dollars. Although Bruce Simpson's advanced designs 
and David Brill's zinc castings are beautifully designed objects, 
they might be considered too pricey for the average backyard 
experimenter. Two regular participants at Kenneth Moller's jet 
propulsion forums have found some solutions for the penny-pinching 
powerplant designer. Read this and the following interview to find 
out how they managed to build some astounding machines on some 
astoundingly thin budgets.  - Larry Cottrill

The Tundra Jet
['Tundra Man' Mike Kirney, interviewed by Larry Cottrill]

The first jet project in our 'Cheapskate Homebrew Showcase' comes 
from Mike Kirney, of Renfrew County, Ontario.  He is known to 
many on Kenneth's forums as "Tundra Man".  After reading and 
posting on the forum for over two years, he finally decided to 
take the plunge and build himself a 1/3rd scale Argus 014 replica. 
[Editor's note: The Argus was the engine which powered the famous 
V-1 "Buzz Bomb" which Germany used against Great Britain in World 
War II. Though primitive by today's standards, the V-1 can 
probably legitimately be considered the first production "cruise 
missile" ever launched.] According to Mike, The only materials he 
purchased for this working model were a 3 x 6 foot piece of 22 
gauge steel sheet, a 6 by 50 inch roll of  0.005" stainless steel, 
and two rods, 1/8" x 36" [one cold rolled steel, and one brass] -
and ended up with more material left over than what he used for
his engine!

Our interview with Mike took place a few weeks ago [mid-April,
2003] - here's what he had to say about building his mini-Argus 

Fully welded pipe of the 'Tundra Jet' (c) 2003 Mike Kirney ALL  WELDED  UP  AND  NO  PLACE  TO  GO
The fully welded tailpipe assembly of Mike Kirney's
'Tundra Jet'. The square plate at the top end of
the pipe in this photo is the not-quite-finished
'front plate', which provides the mounting surface
where the valve plate will ultimately be attached.
Photo Copyright 2003 Mike Kirney

jZ: Welcome, Mike! All right, let's get started. How did you first become interested in pulsejets? Mike: Back in '99, I was an aircraft maintenance student in community college. A passing mention was given to pulsejets in my powerplant textbook. Although the text claimed that the pulsejet had no practical value as an aircraft powerplant, the idea of producing hundreds of pounds of thrust from a simple duct and valve device captivated me. I had no idea how they worked or what sort of operational idiosyncracies they presented until I found Kenneth's forum online, a year later. jZ: How much have you spent on materials for your first engine project, the 'Tundra-Jet'? Mike: The steel sheet was $40 CDN, the roll of stainless shim was $30 and the rods were seven bucks each, for a grand total of $84 CDN. I still have more than 2/3rds of the sheet left and about 4/5ths of the roll of shim. If I bought just a couple more rods, I could make at least two more Tundra-Jets from the leftover materials. jZ: Tell us about the design of this pulsejet. Mike: I decided to shoot for a duct length (behind the valves) of 100 cm. I just divided all the dimensions of the original Argus by 3.3 - many forum members advise against such a simplistic approach but it seemed to make the most sense to me. I wasn't looking to make a lot of thrust, as I intended to use my jet for melting snow in my driveway, plus, by adding length to the tailpipe, I can change the operational characteristics.
An early shot of Mike's beautiful hand-formed pipe
sections, carefully stacked together before any
welding. This does indeed look almost identical to
the original Argus engine pipe -- only the scale of
surrounding objects reveals the truth.
Photo Copyright 2003 Mike Kirney

Stacked, unwelded pipe sections for the 'Tundra Jet' (c) 2003 Mike Kirney
jZ: What about the valve-holder? I know Your intake is a sort of square steel frame 12 cm on each side, enclosing a grid of more-or-less square cells to contain the reeds. Mike: The valve array took the most work to design. I figured my jet was too big for petal valves. Had I used them, each petal would have wound up being almost 7 cm long! I wanted to use the 22 gauge sheet for as much of the jet as I could. Eventually I devised an interlocking set of 10 steel rectangles with tabs and slots cut in them. The horizontal pieces have two holes drilled in them, one behind the other, to form a figure-8. I cut pieces of steel rod 14 cm long and knocked them into the rear-most holes. These rods I brazed in place. They serve as the permanent half of valve holders. After placing the reeds in their respective positions, I then knocked the brass rods into the front holes. The valves are thus held in place between the two rods, the brass ones easily removable with a punch pin for reed replacement. jZ: How will you keep the brass rods in place? I mean, I can see vibration gradually working them loose, or something. Mike: I think I'm going to lash them to the steel rods with wire at each end and then tin solder it all in place. The solder can be easily removed for maintenance.
Setup of the valve plate [unbrazed] (c) 2003 Mike Kirney
The pieces of the valve grid, carefully set up
before brazing it all together. The steel rods are
vertical in this shot; the brass rods aren't in
place, but would be hidden behind the steel rods.
One folded reed will form a back-to-back pair of
valves in each cell.
Photo Copyright 2003 Mike Kirney

jZ: What did you have to do to actually fabricate your reeds? Mike: I cut them from the 0.005" stainless shim with ordinary 8 inch long scissors. Each rectangular reed is 6 cm long and 1.5 cm wide. These pieces are bent in the middle so that they rest like saddles on the steel rods in the array. Each reed effectively becomes two valves when the brass rods are hammered into place. jZ: OK -- let's make sure I really have an accurate mental picture of this. We have a steel rod permanently set. Each valve reed is a rectangle folded in the middle to form a V-shaped piece. The point of the 'V' rests against the rear side of the steel rod, then the brass rod is slid through behind - or inside - the 'V' to lock it against the steel rod in front. Mike: That's it. jZ: How did you handle the hot metalwork? I believe you've said you used conventional torches to do the brazing and welding. Mike: Yes, I did. The first thing I did was clean an area of the steel sheet with varsol and acetone to get all the grime off. Then I sprayed it with a light coat of grey automotive primer. This allowed me to draw easily visible lines on it with an HB pencil. I used a ruler and a triangle to lay out two rectangles, which I cut out with a pair of compound leverage shears. After I removed the primer and pickled the pieces with muriatic acid, I washed them with dish detergent and water and rolled them by hand into cylinders which would become the combustion chamber and tailpipe of my jet. I used an oxyacetylene welding torch to do all the welding and brazing and some of the cutting.
Here's the grid after brazing all the connection
points. Brazing is not necessarily beautiful in its
finished state; the technique is similar to silver
soldering, but at a higher temperature. It is quite
strong, though not equal to welding.
Photo Copyright 2003 Mike Kirney

The entire valve plate completed [brazed] (c) 2003 Mike Kirney
jZ: But you cut the sheet metal with hand shears ... wow. Weren't the cut edges awfully rough and distorted? Mike: Yes, they were. I cut all my pieces a millimetre or two oversize and then I filed the edges down to the pencil lines with a 9" bastard file and an 8" mill file. The shearing and filing took the most physical energy of all, especially the shearing. Sometimes I had to brace the shears on my basement floor and step on them to make the cuts, especially when I was deep into the material. jZ: You said you rolled your pieces by hand? Surely you must have used implements of some kind ... Mike: I did. I used 4" lineman's pliers to bend one edge of the rectangle downwards slightly. Then I placed two 1" dowels, one on either side of the bend and curled my fingers around the inside dowel. I just rolled up the steel like a piece of paper. jZ: Like a piece of paper ... hmmmm, right ... Mike: Well, that's how I got the first edge started anyway. I used a variety of techniques to form the cylinders. In my mind's eye I would break up the circumference of the cylinder into quadrants. I would alternate quadrants, clamping the sheet between the dowels and bending one quadrant in a little, then the other, all the way around, until the edges to be butted were about 5 - 8 mm apart. Then I rolled the bent edge under the flat edge and presto, I had rough cylinders. I used a bit of 1/4" rope as a way to apply uniform pressure to cinch the edges together too.
First weld - the combustion chamber cylinder (c) 2003 Mike Kirney FIRST  TRY  AT  WELDING
Another picture from very early on in the project:
The combustion chamber cylinder, with Mike's first
weld [well, the first in a long time, anyway]. Looks
awfully good to me.
Photo Copyright 2003 Mike Kirney

jZ: Was it difficult to weld your cone and cylinders? Mike: I did practice a little before I started - it was the first time I had picked up a torch since college. I used a #0 tip and about 4 psi on the acetylene. My oxygen regulator was designed for cutting so it was hard for me to tell just how much pressure I had in the hose. I estimate about 7 or 8 psi. I used 1/16" mild steel rod for the welding and 3/32" flux-coated brass rod for the brazing. jZ: With a higher oxygen pressure like that, I'd guess you must have blown through a few times! Mike: Not really. First I put a tack weld every 12 cm or so down the length of the piece. Then I heated the rod just enough so that it would get droopy and stick to the edges to be welded. After I had laid down a few inches of rod this way, I would go back and puddle it all together with the base metal. The biggest problem I had was my workpieces warping and the edges overlapping, especially with the long tailpipe. This really freaked me out at first, but in the end it all turned out okay. After welding, I shaped the cylinders a little more by hammering them over a scrap piece of wood and squeezing them in my hands and between my knees. jZ: What about the cone? A lot of people think they know how to lay out a cone, but then after they roll it together and weld it up, they find out they were way off the mark! Mike: That nearly happened to me. Thank God for Hank bringing it up on the forum. It was his fortuitous comment that made me realize that I had no idea how to lay out a flat pattern for a truncated cone. I did a websearch and found a site with a really good method based on trigonometry. Using that method, I made a template which I traced onto a piece of cardboard. Then I traced that onto the steel sheet. I refined their explanation a little and put it up on my webspace: jZ: Why didn't you just use the well-known program called "Cone"? Mike: I thought about it, but I realized that my developement would be too big to print on a single sheet of letter-sized paper. Believe it or not, I actually enjoy doing trig. I wanted to learn the principles behind the cone development so I could apply them to other shapes as well. jZ: You ENJOY trigonometry? Are you psychotic, or what? Mike: Well, lets just say I am socially functional but as yet, psychiatrically undiagnosed. jZ: How can you enjoy trig? Seriously, Mike ... I detect illness ... Mike: Hey c'mon Larry. I don't make fun of your little tiny jets. jZ: Tiny? TINY!!! My engines will ... uh ... fit into any budget and lifestyle ... they'll uh ... become a novel addition to any home environment ... um ... Mike: Yeah, right ... well then, just cut the jive about my trig fetish, OK? jZ: Oh, all right, we'll try to get back on topic here. You mentioned to me earlier that you actually did some cutting with the welding torch. Isn't that ... illegal or something? [laughing] Mike: Nope. I used a #2 tip to cut out the circles for the valveplate and the frontplate on the duct. It was very quick and easy but I had to file off the inside edges afterwards. jZ: Yes, actually my dad had a rather nifty trick for that. He'd heat a spot up red hot with the torch, then quickly valve off the acetylene and just start moving it along, letting the oxygen stream keep the cut going. It was an amazing thing to see! Now, you have a frontplate that acts as a mounting surface for your valveplate, right? That's pretty heavy stuff compared to the sheet metal chamber -- I mean, welding the frontplate to the combustion chamber must have been a bit of a blacksmith's nightmare, I would think. Mike: Nah, it was easy. I used the same technique as before where I laid down the rod and then puddled it after. There was some overlap left on the inside of the hole so I just puddled that down to a nice round edge. That joint is probably the strongest one on the whole engine. jZ: How do you attach the valveplate to the rest of the jet? Mike: I use eight 5/16" bolts with nuts and lockwashers. They are about an inch long so they should accomodate any gasket I might have to use.
Looking rearward through the fully welded engine,
as seen through the mounted valve plate grid. Note
the slight out-of-round distortion -- while almost
inevitable when fabricating all the parts by hand,
this should have absolutely no effect on running
or performance.
Photo Copyright 2003 Mike Kirney

Looking down the pipe through the mounted valve plate (c) 2003 Mike Kirney
jZ: So ... when do we get to hear this beast run? Mike: Well, the chinook just blew through town today so that usually means we're gonna get one more snowfall this week, then the frost is over until Hallowe'en. I'm hoping I'll have everything good-to-go by the end of April. I'm trying to adapt a fuel system from a 1 lb. propane bottle and an old welding torch I found in my shed. I have an old regulator too. I'm thinking about just using fireplace matches to light the thing, as electric starting seems kind of decadent right now. jZ: Oh, before I forget ... thanks for getting an interview for us with our friend, Mark 'Thixis'. I'll try to publish that right along with this one. Mike: Yeah, Mark's always fun to talk to -- and that dude really builds some weird stuff ... he gets it to run, though! jZ: Well I hope you keep in touch, Mike. I mean, we're going to be hanging from the rafters by our fingernails waiting for your test results! The Tundra-Jet sounds like it's bound to cause a shop class revolution. Mike: [laughing] Ha! Shop class revolution -- I could really dig that! Thanks for interviewing me, Larry. Hey man, I saw some empties under your front deck. Would you mind...? jZ: What, those old Pepsi cans? Uh, yeah, whatever ... go ahead and take 'em. Mike: Thanks, man ... you just never know what you can use. See, I just now thought of this little jet where you'd ... _____________________________________________________ Photo Credits: All photos in this article were provided by, and are property of, Mike Kirney. _____________________________________________________
Mike Kirney grooving on guitar (c) 2003 Mike Kirney
Mike Kirney, of Renfrew County, Ontario, Canada has been
interested in pulsejets for several years, but only started
to build his own a few weeks ago. Mike has also played guitar
[the instrument shown here is a Godin electric from Quebec],
piano, flute and alto sax. He has visited all ten Canadian
provinces and about 20 States of the US, and once bicycled
from Vancouver, BC to San Francisco, CA in nineteen days.
He is very interested in alternative power sources, especially
some new uses for steam. Mike answers to the nic "Tundra
Man" and can be reached at
Photo Copyright 2003 Mike Kirney

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Real Jets, Real Cheap - 
   20th Century technology on a 19th Century budget 
   [Part II]
   Interview with Mark 'Thixis'

Note from the Editor:

There's more than one way to build working pulsejets 'on the
cheap'. In the previous article, Mike Kirney showed how low cost
materials can be used effectively; however, Mike's building
techniques still require a lot of manual skill and effort - 
especially, skills in metal forming and gas welding. The
following article shows a completely different method. This 
does not produce lightweight 'flight engines' [which is what a 
lot of us kind of expect a jet engine to be] but rather, simple, 
extremely rugged structures, built mostly of ordinary plumbing 
parts -- what this builder calls a 'Tinker Toy' approach. As 
you'll see, it's something really different!  - Larry Cottrill

Welding? Who Needs Welding To Build a Jet?
[Mark 'Thixis', interviewed for jetZILLA by Mike Kirney]

Here's the other entry in our 'Cheapskate Homebrew Showcase':
Mark 'Thixis', another participant on Kenneth Moller's 
pulsejet forum, has constructed an amazing array of simple 
pulse combustors using only inexpensive steel pipe and cast 
iron plumbing parts, mostly without precision machining. Mark
lives in the State of Florida, USA. Here he's interviewed for
jetZILLA by Mike Kirney [see my interview with Mike, above] 
and answers some good questions for amateur pulsejetters:

jZ: How's the weather down south, Mark?

Mark: It's great, Mike!  The Spanish Moss is hanging long and I 
can eat my fish now instead of running my sled on it.

jZ: Uh ... I beg your pardon?

Mark: Read my forum posts -- you'll figure it out.

jZ: Um, OK ... I'll do that. You have quite a collection of 
homemade jets. How long have you been experimenting with pulse 

Mark: I have been doodling with pulsejets for about 15 years.

Family portrait of engines & jam jars (c) 2003 Mark 'Thixis'
Except for the original DynaJet [the
engine with the red anodized valve head,
near the center of the photo], all these
are experimental engines and 'jam jar'
combustors Mark has built or modified
from such things as plumbing hardware
and medical implements [and, in some
cases, even glass jam jars!].
Photo Copyright 2003 Mark 'Thixis'

jZ: Wow! That's a lot of experimental experience. What got you interested? Mark: Long ago my brother gave me a Dynajet that he bought in Texas for around $60.00. I didn't fire it up for several years. Then I did, and was surprised at the noise. Later, in college, I started to wonder if I could build one out of water pipe, and it took me a few months of thinking and toying until I got one to run. jZ: What's the biggest jet you've ever built? Mark: The biggest jet I attempted was a 4 inch plumbing pipe which weighed over 40 pounds and was a beast which shook my garage wall, along with all the things hanging on it, when it fired. I cowered and decided the neighbors would complain if I kept the cannon shots up. jZ: Man! You're lucky you didn't get busted! Did it sustain combustion? Mark: No, the biggest I've gotten a continuous run from is three inch diameter [75mm ID], thick-as-can-be threaded water pipe.
This is the 3-inch pipe engine
mentioned above. The valve plate
shown in this month's cover photo
and in the photos below are from
the front end of this engine, and
can be seen from the valve side at
the center of this shot. The reddish
object is the valve head of the
DynaJet, shown here for scale.
Photo Copyright 2003 Mark 'Thixis'

3-inch plumbing pipe engine (c) 2003 Mark 'Thixis'
jZ: What fuel do you use in your jets? Mark: I like to use methanol. It evaporates quickly and is very forgiving with fuel/air ratios. jZ: Tell me about your first jet. How much did it cost? Mark: My first jet cost me about $10.00 in parts if you don't count the spring steel, which was about $20.00 a roll, but you can make a lot of reeds out of it. jZ: A jet for thirty bucks US! What tools did you use to build that thing? Mark: The tools I used were a grinder, drill press, vise, pipe wrench, and a tap for the spark plug. A very smooth edge can be made on a valve plate by inserting a bolt in the middle of the plate and rotating the disk against an edge in order to control the distance.
Valve plate & fuel port assembly (c) 2003 Mark 'Thixis'
Mark's 'bench grinder machined' valve plate at the
bottom, with the fuel port assembly, built up out of
hardware store plumbing parts, bolted to the center.
The ring of nine holes in the plate lets air/fuel mixture
into the combustion zone when suction opens the thin
spring steel petal valves [see bottom view, next photo].
Photo Copyright 2003 Mark 'Thixis'

Here's the valve plate back side, with the
nine valve petals clamped in place under the
retainer [the large washer in the center] --
the central bolt not only holds the retainer,
but goes clear through the plate to support
the fuel port assembly shown in the photo
above. The front side of the retainer is
dome-shaped to allow the petals to open
rearward and land on its smooth surface.
Photo Copyright 2003 Mark 'Thixis'

The entire valve plate completed [brazed] (c) 2003 Mike Kirney
jZ: Thanks for the 'machining' tip, Mark. The classic 21st Century pulsejet is fabricated from thin guage stainless steel sheet. The heat produced by operation can make these glow brilliant orange. Does the thick steel wall of the plumbing pipe glow ever like that? Mark: Even though they are very thick, they glow a dull red, and if mounted on a board with nails to wedge it down, the board will billow smoke from the heat. jZ: Sounds dangerous! What about the zinc coating? Most plumbing pipe is galvanized, is it not? Mark: It is. Once I found a deposit at the tail of a 3 inch diameter water pipe jet. It had formed or melted a ring of zinc or something that I pulled out almost in one piece from the galvanized plumbing pipe after it cooled down. I had previously attempted to grind a flare in the tail [which didn't work with my tiny grinding stones] so I know the ring wasn't there to begin with. The ring of metal was soft and bendy. ________________________________________________________________ CAUTION! Precautions need to be taken when using galvanized or cadmium plated steel in a pulsejet. When the steel gets red hot, the galvanizing or plating will start to burn off -- the smoke-like fumes from this are EXTREMELY hazardous to breathe. When welding such materials, always provide adequate air movement to keep these fumes away from your face [a small 'box' fan is adequate] or better yet, work outside and orient the work so the breeze immediately blows the fumes away from the weld area. When running your jet the first few times, stay on the upwind side so the smoke and fumes aren't blowing toward you. When the engine has been hot enough long enough, the galvanizing or plating will be completely burned off, so this hazard is eventually eliminated. - Editor _________________________________________________________________
Valve plate & fuel port assembly (c) 2003 Mark 'Thixis'
Mark's collection of ignition plugs that
he's used in various homebuilt engines.
Note that some of these are extensively
modified! [The three little plugs at the
left edge are model airplane glow plugs,
for scale. In general, little success has
been achieved by anyone trying to use
glow plugs for pulsejet ignition.]
Photo Copyright 2003 Mark 'Thixis'

jZ: What's the longest one of your jets has actually sustained combustion? Mark: The longest I ever ran one was for about 5 minutes, when I decided to go ahead and let it run the tank dry. jZ: That's a pretty decent run, as far as I can tell. Thanks for dropping by to answer some questions for JetZILLA, Mark. Mark: No problem, Mike. Hey buddy, do you have another beer? jZ: More beer? Who do you think I am, Molson Breweries? Get outta here! Mark: OK, OK. Um ... would be it be alright if I left my truck here overnight?
Jam jar engine from heavy duty pipe (c) 2003 Mark 'Thixis'
One part of Mark's pulsejet hobby is making up
'jam jars'. A jam jar is an 'almost pulsejet' which
sits upright with a small pool of liquid fuel at
the bottom, and runs by alternately firing and
breathing through a single small nozzle at the
top, after lighting with a match. Traditionally,
jam jar engines are made from a small glass jar
[or more recently, plastic bottle] with a metal
lid in which a small hole has been drilled or
punched. Mark likes his a little heftier; the
ruler on the left is a six-inch [approx. 16 cm]
Photo Copyright 2003 Mark 'Thixis'
_____________________________________________________ Photo Credits: All photos in this article were provided by, and are property of, Mark 'Thixis'. _____________________________________________________ Mark 'Thixis' is a longtime pulsejet builder and experimenter living in Florida, USA. No one knows what his last name really is, and nobody knows what 'Thixis' really means. But, if you want to contact him about this article, email: _____________________________________________________



 -   V E R Y   S P E C I A L   O F F E R   -

 F R O M   A   F R I E N D   O F  jetZILLA  . . .
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Get Your Copy of the Original Lockwood Research Paper
   - a 'must have' for valveless pulsejet builders!
offer by Ben Brockert, pulsejet hobbyist

We introduced this offer from my friend Ben Brockert last month. He has
discovered an early copy of the original paper on the Lockwood design, 
prepared for Hiller Aircraft by Ray Lockwood, who was employed by 
Hiller in the 1960s, and is making new copies available to any pulsejet
hobbyist who wants one. I have obtained my copy from Ben, and it is a 
wonderful paper, not overly mathematical, with an excellent description 
of the theoretical and practical advantages of valveless pulsejet 
designs, and of the Lockwood design in particular. It includes some 
performance related graphs and other research data. For anyone
interested in valveless pulsejet theory, this is an unbelievable bargain
for your two bucks (payable through your PayPal account). Ben says:

  In my continuing search for knowledge from the first era of pulse 
  jet research, I recently found a copy of an interesting document. 
  Written by R. M. Lockwood in 1964 and entitled "Pulse-Reactor Low 
  Cost Lift-Propulsion Systems", it includes the basic theory of 
  operation of the Lockwood valveless pulse jet; as well as 
  experimental data on augmentation, fuel efficiency, and noise 

  I'm offering copies of this paper for $2(US)/each, with all proceeds to
  be used in future searches for more documents. Details can be found on 
  my web site at

My advice is, DON'T pass this up -- GET YOUR COPY NOW!

- Larry Cottrill


 F R O M   T H E   M O N S T E R S   G A L L E R Y . . .
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Note from the Editor:

In this feature of each issue, we'll feature one of my own
designs from our Gallery of Hopeful Monsters. These
will generally be jet engines or related equipment that are
PROPOSED designs that are as yet untested and unproven --
BUILD AT YOUR OWN RISK !!! No full-size plans, scale prints
or detail drawings, other than what we show here, are available.
Also, since these are usually just proposed designs that we haven't
even built ourselves, we offer almost no technical information --
these are definitely for advanced experimenters who are used to 
working out the fine points on their own!

So, these designs are mostly presented to give you something to
think about, although advanced hobbyists can try to build them
and get them to run. Let us know if you have any amazing
successes to report!

One of my latest designs, from August of last year, was this
'double barreled' design for a 'reciprocating' pulsejet engine
where each side would assist the other by alternating passage
of blast gases into the chambers, at the same time assisting air
induction via ejector action.

Hope you like it!  - Larry Cottrill

Proposed design for Reciprocating Valveless Pulsejet Engine 
   by Larry Cottrill
Copyright 2003 Larry Cottrill

Basic concept drawing for proposed 'Reciprocating Ejector' engine (c) 2002 Larry Cottrill VIEW LARGE
RECIPROCATING EJECTOR VALVELESS ENGINE The original concept drawing, as disclosed on 07 August 2002. The engine is designed to be fabricated entirely from flat and bent sheet metal, without rolling. Drawing Copyright 2002 Cottrill Cyclodyne Corporation Original disclosure 08/07/2002 on Kenneth Moller's Valveless Pulsejet Forum, as follows: [ Gentlemen - Yesterday I saw Eric's thread on the Pulsejet Forum and took a look at his marvelous renderings, including his 'alternating valve' job -- that led me to think of this valveless reciprocating alternative. This is not quite like the E-P, but is linked at the front end, where the crossover exhaust can drive an ejector to boost the flow into each intake. The idea is to build it with flat plates for side walls and variously bent plates for the pieces seen in section in the drawing (it would be a good project for Ben, who does a lot of sheet work WITHOUT rolling). The 'baffles' at the rear are to keep each exhaust stream from unduly influencing the other half (a la Esnault-Pelterie). Let me know what you think ... L Cottrill ] Theory of Operation When the explosion of the air/fuel mixture occurs in one of the combustion chambers, some of the blast product gases are driven forward and funneled into the wide, shallow ejector channel. The channel turns the gas backward and into the front ejector section which forms the intake throat to the alternate chamber. Ejector action helps draw fresh air into that chamber, where it mixes with the fuel entering via its continuously-running fuel injection nozzle. When the proper ratio of air to fuel is reached, the next explosion in that chamber occurs, reversing the process. By the time the hot gas from the latest explosion reaches the alternate chamber, exhaust gases have almost entirely left the alternate combustion chamber, leaving it in an over-expanded, low-pressure state. The combination of outside air pressure in front of the intake and the ejector action of the blast gas entering the intake throat area should provide very rapid filling of the alternate chamber, to set it up for the next explosion. Also, the hot gas from the ejector channel should aid in getting prompt ignition when a good air/fuel ratio is reached. Note that some ventilated air space should be left between the two exhaust ducts -- attempting to merge them together as a single plate will almost certainly cause severe erosion of the material due to total lack of air cooling. If you decide to try to build a working model of this experimental design, make sure you get plenty of photos and email them to us in GIF or JPG format to display in a future issue [we will make the final decision as to the best ones to use, and we'll show your name as a photo credit.] And, why not try writing an article about building and firing it? We don't pay for articles, but we'd be glad to help you "get your name in print". Also, any author whose article we accept gets a free ad for your e-business or Web site! Naturally, we will provide editing as needed for publication in readable US English. - Larry Cottrill
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   > Metals in Pulsejet Interiors -
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  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: 08 May 2003

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