from the Editor of jetZILLA - the Online Magazine of Amateur Jet Propulsion from the Editor of jetZILLA - the Online Magazine of Amateur Jet Propulsion from the Editor of jetZILLA - the Online Magazine of Amateur Jet Propulsion

The  Reynstodyne FokusTM  low-cost pulsejet project -
August 2004 - October 2004
(last content update: 01 Nov 2004)

Focused Wave Valveless Pulsejet engine running - Photo (c) 2004 Steve Bukowski
    Photo Copyright 2004 Steve Bukowsky
'Short Lady' Focused Wave Valveless Pulsejet engine and designer Larry Cottrill - Photo (c) 2004 Larry Cottrill  
The 'Short Lady' valveless pulsejet and designer Larry Cottrill  
'Short Lady' valveless pulsejet engine on test mount before firing - Photo (c) 2004 Larry Cottrill
'Short Lady' valveless pulsejet engine on test mount before firing


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WORK IN PROGRESS LOG
  Preliminary Design
    Concept submitted:   2004-08-30    
    Design complete:   2004-09-14    
  Working Prototype
    Construction started:   2004-09-15    
    Construction completed:   2004-09-22    
    Testing started:   2004-09-22    
    Testing completed:   - N/A -        
 


E X P E R I M E N T A L
---   R E A D   T H I S   N O T I C E   ---
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  1. LIMITED LICENSE IS HEREBY GRANTED TO BUILD AND MODIFY THIS DESIGN IN SINGLE UNITS ONLY, FOR NON-COMMERCIAL PURPOSES ONLY, such as for personal education and amusement, and including use of the design as a powerplant for an unoccupied model vehicle, UNDER THE REMAINING PROVISIONS OF THIS STATEMENT OF TERMS AND CONDITIONS:
  2. PRODUCT DESIGNS SHOWN ON THIS PAGE ARE proposed embodiments of INVENTIONS OF LARRY B COTTRILL, and any or all rights may be assigned to Cottrill Cyclodyne Corporation (a for-profit corporation registered in the State of Iowa, USA);
  3. PRODUCT DESIGNS SHOWN ON THIS PAGE ARE UNDER DEVELOPMENT AND THESE PRODUCTS AND THE UNDERLYING INVENTIONS potentially embodied in such products ARE NOT BEING MARKETED NOR OFFERED FOR SALE, pending completion of development efforts and possible patent application;
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    I.   O R I G I N A L   S C A L E   D R A W I N G
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Disclosed on Kenneth Moller's Ramjet Forum - 14 September 2004:
    
Scale drawing for 'Short Lady' Focused Wave Valveless Pulsejet engine (c) 2004 Larry Cottrill VIEW LARGE
IMAGE
 
FOCUSED WAVE VALVELESS PULSEJET ENGINE - 'Short Lady' The scale working drawing, as disclosed on 14 Sep 2004. The engine was designed to be fabricated entirely from mild steel tubing and sheet steel, with fully welded construction. The first prototype was built by high school student Steve Bukowsky of Connecticut, USA. I did not show engine mounts on the drawing. Drawing Copyright 2004 Larry Cottrill



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    II.   W O R K   I N   P R O G R E S S   P H O T O   D I A R Y
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Photo Diary: Building and running 'The Short Lady'
Focused Wave Valveless Pulsejet Engine
by Larry Cottrill, Editor, jetZILLA Online Magazine
 
       - All photos Copyright 2004 Steve Bukowsky and Larry Cottrill - 


The original Focused Wave Engine prototype, as built and run by Steve Bukowsky (c) 2004 Steve Bukowsky
Steve Bukowsky's original 'Short Lady' build, in good lean running 
on propane vapor fuel - exhaust ejection from the rear-facing intake 
can be clearly seen in this photo. This shows Steve's final method 
of supplying fuel vapor straight down the center of the intake.
Steve's 'Short Lady' started and ran on the very first try! 
Photo Copyright 2004 Steve Bukowsky


Table of Contents [Sections I-V below]:
I.  Getting started - "parts is parts"
II.  Preliminary welding
III.  Spark plug mount
IV.  Welding on the tailpipe tube
V.  Fitting and welding in the intake tube

Table of Contents [Sections VI-VIII go on to Page 2]
VI.  Engine mount blades
VII.  Welding on the front end dome
VIII.  Static testing - starting and running with propane
IX.  Steve's Short Lady Prototype Run-Time Photo
      Gallery
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I. Getting started - "parts is parts": Next section   Back to Contents   Top of page   To top of page 2 Subscribe to jetZILLA Online Magazine (it's FREE!) Not having an equipped shop, I had no good way of rolling the combustion chamber wall and end cones myself. Since Steve had obviously done such a nice job making these 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, alonside 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: Steve Bukowsky's finished engine alonside the combustion chamber parts he made for me - Photo (c) 2004 Steve Bukowsky Photo Copyright 2004 Steve Bukowsky If you have a way of smoothly rolling your own cones, you can print these graphics and scale them up so the squares form a 1 cm grid, then cut out the patterns to make your own cones out of 1 mm sheet steel. If you want, you can make the hole for the intake after rolling and welding the main cone, but you can still use the pattern to locate the hole accurately. If you want to use a pinched intake pipe [recommended], use the longer, diamond-shaped hole outline. Important: You should use the outside edge of each heavy black outline as your cut line. Main Combustion Chamber Cone Pattern Scalable cutting pattern for the combustion chamber cone - (c) 2004 Larry Cottrill Scalable pattern for the combustion chamber cone - Copyright 2004 Larry Cottrill Combustion Chamber Dome Pattern Scalable cutting pattern for the combustion chamber dome - (c) 2004 Larry Cottrill Scalable pattern for the combustion chamber dome - Copyright 2004 Larry Cottrill II. Preliminary welding: Previous section   Next section   Back to Contents   Top of page   To top of page 2 Subscribe to jetZILLA Online Magazine (it's FREE!) The combustion chamber wall cone side seam was welded in several passes, to minimize distortion. The three tack welds were blended in, but left pretty good sized lumps; I simply dressed them down later on, using a flat file. Both cones I prepared looked just fine, but were slightly out of round from welding. This was easily corrected by careful squeezing in the bench vise later: One combustion chamber wall cone, with the side seam finish welded (c) 2004 Larry Cottrill Similarly, the front end dome seams were quickly finish welded: Two front end domes, finish welded (c) 2003 Larry Cottrill III. Spark plug mount: Previous section   Next section   Back to Contents   Top of page   To top of page 2 Subscribe to jetZILLA Online Magazine (it's FREE!) Here's a shot of spark plug mount welding technique. The center hole in the dome was filed out just enough for a 3/8-24 bolt to go through from behind, and a nut tightened on. Two more nuts [which appear white in the photo] are threaded finger tight on top of that, to protect the bolt threads from the torch heat. This weld takes a fair amount of heat and filler rod, and you have to be careful not to slop any weld metal onto the outer nuts, so they can be removed easily afterward: Welding the spark plug mount nut to the front dome (c) 2004 Larry Cottrill After cooling, I applied penetrating oil and loosened the nuts. Removing the outer nuts was easy, but the bolt had to be extracted from the welded nut using a box-end wrench from behind while gently gripping the dome in the bench vise. Here's the finished product, with the second dome in the background, waiting to be done in the same way: Finished front dome with spark plug mount fully welded in (c) 2004 Larry Cottrill IV. Welding on the tailpipe tube: Previous section   Next section   Back to Contents   Top of page   To top of page 2 Subscribe to jetZILLA Online Magazine (it's FREE!) Next, the tailpipe tube was cut from a piece of TV antenna mast tubing. I found that for a perfect fit between the combustion chamber cone and the tailpipe tube, the front end of the tube had to be expanded a fraction of an inch. This was done by heating and gentle nudging all around with a small ball peen hammer until it was a near-perfect fit. Then, I set up a careful 'temporary jig' of firebrick to hold the pieces in alignment for tack welding. Proper alignment was established by sighting down the tube from the rear and adjusting as needed during tack welding. Finally, the finish weld was run around the seam in four passes, concentrating on using a minimum of filler rod to try to keep the inside surface as smooth as possible. Here's a shot of the tack welding operation, showing the firebrick 'jigging' - note the plain brick at the rear, pinning the tailpipe to hold it steady: Welding the combustion chamber cone to the tailpipe tube (c) 2004 Larry Cottrill The finish weld is reasonably reinforced, smooth inside, and holds the chamber in near-perfect alignment with the tube [smoothness is critical here; a slight error in alignment is of no consequence]: Finish weld joining the combustion chamber cone to the tailpipe tube (c) 2004 Larry Cottrill V. Fitting and welding in the intake tube: Previous section   Next section   Back to Contents   Top of page   To top of page 2 Subscribe to jetZILLA Online Magazine (it's FREE!) Steve followed my design exactly, using 3/4-inch EMT [rigid electrical conduit] to built his intake tube and flattening the lower end slightly. The hole in the chamber has to be placed as accurately as possible to the design location shown on the drawing. Note that Steve chose to fit his intake as practically the last step in building his engine - note, too, the beautiful intake flare hand-formed from sheet metal and welded onto the outer end of the tube: Steve's intake went into his build as the last step - Photo (c) 2004 Steve Bukowsky Photo Copyright 2004 Steve Bukowsky Based on Steve's experience running his build of this engine, I felt I could try reducing the intake to 5/8-inch EMT. Also, I decided to leave the tube round over its whole length because of this smaller internal diameter. I formed my flare just by heating and hammering, and mine is not as smoothly formed as Steve's finely crafted example. The hole is formed by drilling and then hand finishing with large and small round files, trying to get the most precise location and fit possible: Fitting the intake tube into the combustion chamber wall at the precise design location - Photo (c) 2004 Larry Cottrill I wanted to mount the intake tube before welding on the front dome so that it would be possible to visually inspect the lower end of the tube for perfect alignment in the middle of the chamber. I jigged the intake for tack welding by using a 5/16-inch bolt and nut and an old C-clamp, set just tight enough to hold it: Jigging the intake to the chamber cone with a bolt, nut and C-clamp - Photo (c) 2004 Larry Cottrill The end result - the intake tube, finish welded into the chamber wall: The intake tube, finish welded into the chamber wall - Photo (c) 2004 Larry Cottrill Previous section   Next section   Back to Contents   Top of page   To top of page 2 Subscribe to jetZILLA Online Magazine (it's FREE!)
Multi Media Imaging, Des Moines, IA
All film processing and negative 
scanning for Larry's shots was done by

          Multi Media Imaging
          1526 Walnut Street
          Des Moines, Iowa  USA  50309
          515-309-3456
          www.multi-media-inc.com
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