It's never been my policy to join in the April 1st madness that many magazines and Internet web sites indulge in, so rest assured, everything you read in this MEN issue is intended to be 100% accurate and straight. If it looks a bit odd, that's probably because I've made Yet Another ghastly booboo, like the gears of the Vega that don't exactly mesh (as you can read below). The photo of Les Stone's Mastiff has nothing to do with anything except it's a nice photo of an engine which Les says starts so easily and runs so well that it has more running time on it than any other in his rather large stable of home-built engines.
On the home front, the motor is still not back in the Myford, and the rainfall continues to be distinctly odd. In my area, the water in the reservoirs has not reached a level where authorities are prepared to relax the water restrictions, although they did announce we were in for a "wet weekend" during March. I sat around looking at clear blue skies muttering dark invocations at all weather forecasters, their parents, and the horse they rode in on, only to discover from my colleagues on Monday that the "wet weekend" meant we were allowed to wash our cars and water the garden! Oh well, can't say I really wanted to do those things anyway. Regarding the Myford and changing the single phase AC to a speed controlled converter setup, I got a lot of mail all saying, "do it; you'll never regret it". Maybe I can blame my inaction on knowing I really should go motor hunting. The result is (almost) no progress on anything except software related stuff that has no direct bearing on the subject at hand. And while I'd thought this issue might be a bit smaller than usual due to being motor-less, this turns out not to be the case. Let's start off with some house-keeping:
Product Review Feature
MEN has reviewed things other than books in past, though the review generally got placed in the book review section (like Lee Hodgson's excellent nine cylinder radial plans and Todd Snouffer's LME-370 three cylinder radial four-stroke plan set). I don't get enough stuff to do regular product reviews, but figured that when I do, they should get their own heading, and in time, a index to all past reviews. So, you may have noticed that a new item called Product Review quietly crept into the "Regular Features" section of the monthly index last month. The first "official" one was the Puck Side Valve plan set, while the first actual one should have been the Bob Shores' PeeWee V4 casting set that appeared the month before (the photo here shows progress being made by Bob Shutt on his rendition of this engine). This month, we have another: a PCB for EDM. I have one more in the pipeline for next month, but I can't review stuff I don't have, so if you, or someone you know wants a model engine, or model engineering related product reviewed in a place that reaches 20,000 unique web site visitors per month, contact me. As it says in the footer that nobody reads: with few exceptions, stuff sent for review will appear here. With fewer exceptions, stuff not sent, won't!
As further inducement, here's a snapshot of the "Visitor Map" that appears on the Editorial page footer, taken on April 1, 2008 at 11:45 PM, GMT (or UT, or "Zulu", if you prefer). This would be about the peak geographic distribution for any month as regular visitors know the new page posts on the first of each month. But other times during the month are not all that quiet, as you can check for yourself by looking at the real-time map in the Standard Stuff section.
An email from Marco Mazzola (Palermo, Italia) directs us to his Marco CNC website where he has posted photos of his new 50cc, five cylinder radial. The site is Italian language only, but pictures, as always, speak loud enough and you can follow links to other web sites, plus Marco's own CNC flat-bed router setups which I presume are used to make model airplane kits. Very nice work.
Back in December 2007, we saw the work Bruce Satra, Bob Roach, Aaron Novak, Otis Baker, and others are undertaking to improve the power, reliability, and ease of construction for the venerable Morton M5. Bruce sent me a couple of progress drawings during March that show the general arrangement, together with a comment to the effect that engine is 21cc, compared to the M5's 15cc. Showing a remarkable amount of stupidity, even for me, I asked if this had been accomplished by bore, stroke, or both? The answer was the M5's cylinders are 3cc and the SM-7 has seven of them. Doh! Bruce was kind enough to point this out without any other comment.
Work is still not finalized, but the head castings now have pads either side of the spark-plug boss at the rear so that the exhaust and inlet locations can be moved to make pipe bending a lot easier. The pads will even accommodate 5/16" gland-nuts to secure and seal the pipes. Aaron Novak, an engineer with the development labs at Mercury Marine has contributed revised cam lobes and 9/32" diameter valves (original Morton valves have 1/4" diameter heads). If the inlet and exhaust pipes are increased from 3/16"OD to 3/16"ID, Aaron reports that computer simulation shows that the engine flows much more air than before, more even than O.S. and Saito engines of the same displacement. Meanwhile Otis is regularly flying his improved M5 in a biplane and plans fitting an on-board electric starter (though he may elect to leave the starters battery cart on the ground ).
Crow on Toast
Sort of suspected the Vega 30 plans published here last month might contain a bug or two, but never suspected the two bugs would be such big and ferocious ones! Malcolm Beak got all enthused over the design and luckily, within a day or so of initial release, emailed with some questions that led to a couple of quick-smart revisions to the plan set. Last month's page got a big red warning banner added that if you downloaded the plans early, you better go grab another copy as (i) the spacing of the cam bushes in the backplate did not correspond with the placement in the crankcase separator, making the engine tricky to assemble, and (ii), the pockets in the Ricardo head as drawn would force the valves to valiantly attempt to lift the roof off (someone is going to lose there). These issues, plus some minor things have all been addressed and while I'm munching my crow with a side order of spam, Malcolm is planning two Vegas, one of which will be water cooled (look up his other engines in the Gallery and you'll understand this better). While on the subject, Vega designer, John Harbone, wrote to say that he tried placing the glow plug all over the place during development and was unable to measure any difference, so it ended up where it did for aesthetic reasons alone! Shows that "scale effect" is a significant factor in our little engines and what is true at "full scale" is not always so in miniature.
The Last Word on the First "Diesel"
Outside a dwindling number of Flat-Earthers, it's universally accepted that the first model compression ignition engine (aka "diesel") was the ETHA (see MEN Feb 2005, and others). But who was responsible for the ETHA, and when did he or they start work on the concept? Peter Scott (Hampshire, UK) has been kind enough to supply some remembrances and rather compelling evidence. While living in Switzerland during the 1970's, Peter met with one Herr Feucht, who until about a decade previously had run a model shop on Zurich's Bahnhofstrasse—now one of the most expensive shopping streets in the world. From him, Peter obtained not one, but two original ETHA engines: a small finless one and what Peter describes as a "big ugly one". They came with copies of the original Swiss patent which had been granted to the designer/inventor, one Ernst Thalheim—"E Tha", get it? As Peter says, very handy having a name that abbreviates into the prime combustible component in his invention's fuel! Anyway, it's the date on the patent that is the killer: December 17, 1928! This raises the question why it took about ten years for the first engines based on the compression ignition principal to appear in Europe. But at least there is now no doubt in my mind at least regarding where, when, and from whom the concept originated.
Pete Buskell's Engine Designs
Earlier this year, a picture of a rather unusual engine popped up on a NFFS (National Free Flight Society) forum, identified as the original work of the late Pete Buskell. The engine seems to have an extra cylinder providing additional pumping and while the Motor Boys were tossing around wild speculation regarding what it might contain, I received an email from Pete's son, John, who offered to provide details and pictures of his father's engine designs. To show just how small the world is, it turns out that John lives in Canada, close to Adrian Duncan, and the two had been in contact over a comprehensive article on the ED Racer that Adrian is preparing for us. So click on the link for an article, written by John on Pete's efforts in engine design and modification.
Or to be more precise, lack thereof. At least the #1 engine is now bolted down to a plank for test running and a high resistance problem in the traditional tungsten points chased out of town (or to the city limits, at any rate). Still no tank hookup, but I have bought a length of cord and practiced pulling the engine over. This trial has told me that I need to make the groove in the pulley larger, but we are getting there. There are still a couple of details of the build to document for the Whippet Construction Log. I have lots of photos cached, waiting on words to go with them, so this month we look at the pre final assembly stage that I think of as the Fiddlin' and Fettlin' process.
Product Review: EDM Electronics
Remember the Spark Erosion Machine described here a year or so ago? This device saved, if not exactly my life and sanity, at least my Cirrus. The design came from a book by Ben Fleming called The EDM How-To Book, which was our book review subject in December, 2006. Ben has not been idle and continues to refine his design, as well as make it easier for potential EDM'ers to take the plunge (excuse the pun) with confidence. As mentioned in the review, the majority of folk tackling this project will be competent machinists with little or no experience in electronics. This has not stopped many from reproducing Ben's design, but the wiring up of integrated circuits and things can be a show-stopper for some, so Ben has developed a printed circuit board (PCB) that greatly simplifies construction and almost completely negates the chance of accidentally getting something badly wrong. Last month, Ben very kindly mailed me a "populated" board for evaluation. He notes that he's made several changes in the circuitry that greatly reduce the work load on the servo driver chip, resulting in a more stable burn, plus the ability to work with smaller capacitors and electrodes. So far, I've only used my EDM for brute-force removal of broken taps, studs, and drills, but the quite active traffic on the Yahoo discussion group dedicated to Ben's EDM design show that many builders envision using the machine to create complex shapes in hard metals that can not be done any other way.
The epoxy PCB is double sided, thru-plated, solder masked, silk screened, and measures approximately 4" x 2.5". As can be seen in the photo, you can mount standard modular PCB screw terminal blocks for the connections, or solder directly to the lands. It also includes "utility" solder pads. These simplify future enhancements by providing mounting for new components which can then be jumpered to wherever they need to be. The layout is compact, without being crowded.
When time permits, I'll drop the new electronics into my controller box and report back on the observed differences. If you are in need of an EDM and are prepared to trade time against significant $$ savings, contact Ben Fleming for copies of the book and circuit board.
New Books and Magazines This Month
March provided some great reading in the form of ECJ Volume 32, containing issues #181 through 186. I know that a lot of you take your ECJ in small doses, so what follows will probably be old news, but I like the "bound" volume format and so I'm happy to wait the year, or whatever, until a new set of six issues is released. When he mailed this one to me, ECJ editor, Tim Dannels remarked that he thought I was going to like this one—which is strange because I like them all, but Tim was right—Volume 32 has a number of articles that certainly pressed my buttons, like new insights on the Morton M5 and ELF "Corncob", including the diesel conversion made by our own Stan Pilgrim. Then there's the OK Flat-four, complete with photos of the die used to produce the crankcase and the hitherto unknown fact that crankcase castings for the OK Twin were made by blanking off half of the flat-four die cavity!
For engine builders and restorers, Roger Schroeder's Engin-uity column has lots of good tips and while there's overlap to what you will have read here, I see ECJ and MEN as being complimentary to each other. Roger has insights I don't and I have mistakes he doesn't (but my format allows for lots more photos). Looking in the advertisements section of the issues, I note that Tim has reduced the price on the earlier bound volumes of ECJ, and as I've said before, if you don't have a full set, you really should, so here's your chance. See the Engine Collecting web site for ordering details. This one gets top marks: Five Stars .
Engine Of The Month: KK Cobra
This one hales from England, not the deep south of the USA, and represents a "bold" attempt by the respected English kit maker, Keilkraft, to enter the 1/2A glow market in the early 60's. To completely spoil the story for you, this move was an abject failure, even though the engine itself was not awful, and more important, was most definitely not made from the Cox parts bin as many—including yours truly—had previously assumed. Adrian Duncan came into possession of two of these relatively rare birds and produced a long piece on the engine. I took out my blue pencil to cut it down to less than epic proportions and ended up adding more words on the associated KK RTF entry, discovering in the process that Eddie Cosh, the editor at Model Aircraft magazine (rival to Aeromodeller from the late 40's to mid 60's when they merged) had become the General Manager at KK, meaning there were two Eddies there to confuse matters: founder and Managing Director, Eddie Keil, plus Eddie Cosh. Always good to see another piece of the giant jigsaw fall into place. So visit the new Cobra 049 page and prepare for a protracted and comprehensive read, because much as I tried, I just could not find much to prune which was not germane to the story, plus I'd be a great one to point the finger at anyone for verbosity!
Tech Tip of the Month
Despite working at a University, I don't ride a bicycle. In fact, bicycles are an enigma to me—barely one step down the danger scale from those motor cycle things ridden by temporary Australians only because bicycle accidents tend to happen at lower speeds. So when this photo arrived from a reader building a small Dart inspired diesel, I thought to myself that steel was not the ideal choice for a conrod, but cutting one from a chain sprocket would at least make for a cheap supply of high tensile material. Seems a better knowledge of modern technology would be a good idea as I'm told that the rather worn out sprocket is forged aluminum, thus making it an ideal source of material for the rod on a small engine. Forged conrods were a favorite of model engine manufacturers in the 50's and 60's as it results in an increase in tensile strength. How much is open to debate. I recall reading in Graham White's book on the P&W R2800 that the forged crankcase was 50% stronger than the cast case. Castings are not that strong, so this is no great indicator, however the point is that forging—which is generally accomplished by subjecting hot metal to a high impulse impact in a strong die sitting on a "seismic mass"—results in some increase in strength from the native state of the metal.
Obviously, the driving sprocket on a bicycle is going to need to be strong if made from aluminum. Some research suggests that forging sprockets is primarily intended to align the grain of the metal into the wave-like profile of the teeth, so there is some question in my mind of whether the section of the sprocket the rod is cut from is actually deriving benefit from from the process, or whether the wavy grain actually results in a less stiff rod in compression. And I've not tried it myself, so this tip is offered as a thought to file away, especially if you have access to a ready supply of retired sprocket segments. Must visit the campus bike shop next week and ask if they have any forgeries they want to part with...