Under the theory that my Editorials have become a bit predictable of late, I'm going to try to be a bit different by starting off on topic (for a change), then go way off before cunningly returning to the core subject of model engine making. So we start in the February 2009 issue of the British publication, Model Engineers' Workshop that arrived at the very end of January. The cover picture shows a fine example of the GHT Versatile Dividing Head (VDH), a set of castings for which reside under the bench, awaiting The Day. The issue contains a good article on knurling by Dave Fenner. In this, Dave includes examples of prop drivers he made to restore an ED Racer and ETA 29 using plunge knurling with a shop-made bevel knurling wheel. This sort of tool is illustrated in the How To Knurl Prop Drivers page, and in fact, Dave says that,
"[my] line of thinking was reinforced by some information found on the internet
via the excellent Ron Chernich web site, www.modelenginenews.org
Thanks, Dave. Crediting your sources is both appreciated and ethical. The results of your research and development appear excellent, not to mention the fact that you've actually built the bevel knurl mentioned in the How-To page that I've been dreaming about making for a decade or more.
Now we wander off topic. notice the "www." prefix in the above quote? A lot of us recite this as dub-dub-dub because "double-yue", or even "dub-ya" said three times in quick succession is way too much of a mouthful. The letters are an acronym for [the] World Wide Web. The dot after them indicates that www.modelenginenews.org is a subdomain of the modelenginenews.org domain, which is a subdomain of the top-level domain called org, for organizations. So what does all that mean, and why should I care? Well, where I'm going is to point out that the dub-dub-dub is redundant, outdated, deprecated, and the world would be a better, simpler place if we all just forgot about it! Mostly—it's just noise that takes up print space, adds no value, and can be safely ignored—Mostly. For instance, if you enter modelenginenews.org into your browser address bar, you will end up at the same place you would if you had prefixed it with the www. subdomain qualifier. This is resolved by the host server without me, as webmaster, having to do anything at all. This is true in the majority of cases today, though I kinda suspect there will be an ancient domain name server setup someplace on an antiquated piece of hardware that actually requires you enter the prefix, hence my "mostly" qualifier.
The Internet existed way before point and click web sites. The web browsers we take for granted today had to wait for faster computers with good graphics capability and fast, reliable, inexpensive networking (who remembers email through acoustic couplers?) The appearance of the dub-dub-dub subdomain dates to the birth of the Browser and made sense at the time. It was intended as a way of distinguishing those Internet sites that provided point-and-click content through a server running on port 80 that provided hyperlinks embedded in documents, from those that did not. Today, nearly all domains in the Internet do this. Got an email from someone you don't recognize? Strip the mumble@ from the address and enter the rest into your browser. In the majority of cases, you'll get the index page of a web server running at that address (and may be able to figure out from what that tells you if you want to reply, or not). No "www" required.
MEN has two actual sub-domains. These are maintained for Classic Model Airplane Engine Construction Kits (classic.modelenginenews.org), and Vernal Engineering (vernal.modelenginenews.org). Try entering either into your browser, both without, or with the www. prefix. You end up in the same places, regardless. You don't even need to enter the "http://" prefix. This is the protocol to be used in establishing the connection. If you leave it out, modern browsers will automatically assume http (Hyper Text Transfer Protocol), using the default port 80. So the take-away is communicating web site addresses in pure print media is hard enough to get right as it is without extra, unnecessary stuff! Editors and Authors: increase your Signal to Noise ratio. We're big kids now. We'll figure it out.
A last observation: all the stuff in a web address up to the first slash (if any) is case insensitive. ModelEngineNews.ORG is juat as good as any other combination. If there is a slash, it will always be a "forward" slash (ie, a '/'). I cringe when I hear radio and tv announcers vocalizing web addresses with the mouth-full "blah-blah, forward-slash, blah, forward-slash...". Well duh! The RCF 1738 specification for URL's says that a back-slash is illegal in an address, so just 'slash' will do; no qualification is necessary! But after that first slash, we are into the path to the resource requested and depending on the host operating system, this may be case-sensitive.
Ok, enough. How can I get back on-topic? With difficulty, I suspect... We started with Dave Fenner's article and his neat bevel knurl that produces better plunge knurls without the skipping effect described on the how-to page. Here's the one devised by Dan Calkin and used to produce the prop drivers for his exquisite little Elfs (like 'em or hate 'em, they are nicely made). The photo comes from John Brown's book on Dan Calkin and I've spent hours inspecting the photos of the Elf tooling. More ideas per square inch than you'll find anywhere (there may be more total ideas on this web site, but their density would be per acre in comparison ). Finally, be sure to check the New and Updated pages list for Feb 2009 where you'll find additions to Watzits and the Gallery. Now that we are sort-of back on topic, a moment for a message from your Webmaster..
Red Faces, Again
For a day or so at the start of last month, the ACE 0.5cc diesel review page contained incorrect information. This was corrected as soon as it was brought to our attention, but if you read it at the start of the month—as I know a lot of you do—you should have another look; we had the bit about the introduction date and the company behind the engine very wrong. All this falls on my head because what appears here is my decision. Luckily, I have no trouble digesting tasty crow pie (see October 2002, January 2004, and many others). Nor do I have a problem with confessing to having made a mistake! But I really do try hard to get my research right using a library of old books and magazines the cost of which I don't like to think too closely about, aided by a circle of knowledgeable friends. Sadly, there are holes in the magazine collection and not everybody knows everything. So errors, omissions, and distortions are going to occur. The reader who set us straight on the ACE suggested a system of "peer review" prior to publication. Not a bad idea, but not one I have the bandwidth to implement on a pro bono web site that seems to be consuming more and more of my limited time. Besides, once a page appears, it gets minutely reviewed by an army of peers and su-peers! As said before, if you know I've got something wrong and can provide enough evidence to back up your assertion, I'm more than willing to fix it and chow-down on another of those pesky black birds the following month. And while on the subject of the ACE...
The MBI plan set for the ACE has been completed and, as Neddy might have said, The Boys have closely examined them with an intense scruit. After some corrections, Roger Schroeder made the split cylinder pattern, I made the one-piece crankcase pattern, David has obtained molded fuel tanks, and we are getting ready to build reproductions. The photo here shows Roger machining the exhaust stubs of a test cylinder using a tiny parting tool in an adjustable boring head. I was considering making a piloted, hollow, rose cutter for the job, but Roger's idea has the appeal of simplicity, provided you have the vertical lathe slide and adjustable boring head. Eagle-eyed readers will notice from the casting that the pattern for the head is split at 90° from where it sat on the original. This was done for two reasons. First and most important, it provides an easy way for future collectors to distinguish between originals and our reproductions. Second, like all good software developers, we're lazy! Why pass the parting line through two little bosses and go through all the registration drama that causes when it only needs to go through one!
At this stage, we are still adjusting the patterns and have to prove that the drawings result in a runable engine before we make any decisions on making plans and kits available through Roger's Classic Engines. All being well, the ACE will get the traditional MEN construction series write-up, described warts and all and I've no doubt we'll all learn something new in the process. And yes, we most definitely are having fun!
Yet More ACE Madness
Where will it end? Ken Croft spotted this one on eBay at the end of January. It's what you might call an ACE Clunker, but fully restorable to running condition by an experienced builder. The engine appears to need a new piston, conrod, prop driver, and spinner nut. We can't tell in this photo if the case is stamped with the name and serial number, but the tank with flip-top filler and NVA are complete and original. Notice also the lateral parting line in the cylinder casting. There is some minor fin damage, but that almost adds character to the little guy. This was one of those rarities on eBay: an actual, genuine, auction! No "Buy It Now" rip-off. But apparently some people knew what they were looking at and even with two days to go, it had reached a staggering £67.55 (US$94 and AUS$145). As might be expected, there was a furious flurry at the close and the lucky new owner—certainly not one of us—parted with £112 (US$160, AUS$247) showing just how desirable the little ACE has become, to some.
Caveat Emptor Drone
And while on the subject of eBay Buy It Now offers, you may have noticed these sets of castings for a reproduction Drone fixed compression diesel on offer for US$30, plus postage. The vendor is a well respected, honorable, and reliable gentleman, and that praise (plus the title of this item) should warn you that there is a "but" coming. As openly described in the item description, these are reproduction castings originally intended for a project that failed to eventuate. They are investment cast and at first glance, will make a fine engine—for those with the skill and equipment. The problem lies with the crankcase wall thickness and the slight concentricity error. After machining, the walls of the case are going to be marginal with regard to what would be considered the minimum for a thumping .29 cuin diesel where the thin case wall must absorb the pounding transferred from the crankshaft housing. Yes, many a glow engine has case walls this thin, but diesels run at about twice the compression ratio and the mixture detonates rather than burns, meaning everything is under significantly increased stress and needs to be stronger. This may not be a problem to builders who want to build a historic replica and demonstrate it running a few times before it retires to the glass cabinet. But I think that if subjected to actual use, you'll have problems, and don't even think about crashing it! All this adds up to what the title says: let the buyer beware. But if you go into this with your eyes open and are a careful, experienced machinist with significant engine building experience, you should end up with a nice replica, albeit a bit of a Hanger Queen. I'm even half tempted myself...
How's Your Italian?
Here's the first modern, up to date, authoritive, book on pulse jets to come along since CE Bowden's 1948 "Model Jet Reaction Engines". The author is long-time MEN supporter, Giancarlo Mensa (see Giancarlo's web site which he says will get English text Real Soon Now that the book is done ). The title, Guida al Pulsogetto translates as "Guide to the Pulsejet" and represents Giancarlo's attempt to explain the history and the operating principles of this engine. The book was published in December 2008 and was promoted in the last issue of the Italian magazine, "Modellismo". By reports, sales of the all Italian printing are going quite well, considering the rather arcane subject. Giancarlo says if the book is successful, an International edition in English will be considered. Pulsogetto comprises 352 gloss pages, 24 x 17 cm, with more than 240 illustrations (photos, drawings, etc), two Appendices with tables, and full construction drawings of no less than twenty-one different pulsejet engines! You can order a copy on line at Bancarella Aeronautica" (Turin). Tell them MEN sent you and don't be surprised if they say "who?", or maybe they'll figure it out send us a review copy.
The Disc Valve
This month's part in Gordon Cornell's Model Engine Development series describes how any why he developed a rotary valve for the ED Super Fury and his subsequent analysis of the change in performance this made. As usual, Gordon gives us some historic background and describes the evaluation and development process in a logical progression. In this part, he describes a number of aspects relating to the disc valve that some experts and some non-experts (like yours truly) had not previously considered, such as paddling load and how this might be reduced, or made worse! Click here to go direct to this month's installment. All are linked by forward and back buttons at the bottom of each part, plus a direct access index on page one.
New Oliver Tigers
If you've been left with your jaw somewhere around your boot laces over the prices that Oliver Tigers have commanded on eBay over the years, then you may be pleased (didn't buy it), or alarmed (went temporarily, certifiably, insane. Bought it) to hear some news that appeared in the February issue of BFMA News (BFMA is the British Model Flying Association; the equivalent to the US AMA and the Australian MAAA):
Very recently the news has come that Oliver Engineering
has been taken over by a precision manufacturing company based in the Midlands and that full production of a wide range of the marque is about to resume in the near future. Tom Ridley, the owner and leader of the team, says that John Oliver himself will be chief consultant to the project and will oversee manufacture in the initial stage of the venture. All the existing stocks, parts, dies, and some tooling from the original company will be used for the rebirth of engine production. Such a bold step in these times deserves to be given the full support of the modeling community and [BFMA News is] pleased to publish details of some pricing for the first units, as follows. (As these are not the only intended products in the range, watch out in future [BFMA News] issues too!).
|Oliver Tiger 2.5cc Marks 3 & 4: ||£155|
|Oliver Tiger 2.5cc Mark 5: ||>£210|
|Oliver Tiger Cub 1.5cc Mark 2: ||>£155|
|Oliver Tiger Major 3.5cc: ||>£165|
|Oliver Tiger Cub Schnurle: ||>£165|
For Modellers who wish to place orders for a new Oliver engine, Tom's email address is firstname.lastname@example.org. Let's hope this signals the revival of another engine maker in the UK!
And thanks go to Ken Croft who spotted this and forwarded it to us at the 11th hour for publication in this issue. Those prices seem very reasonable, especially compared to those seen at auction. Olivers have never been cheap, but that has never been a problem to competition modelers either. The important and unstated message is a that full company backing for the product, with spares and repairs etc, will make the Oliver an engine which the owner is prepared to actually use, rather than hide in a safe deposit box for the occasional private fondle.
New Books and Magazines This Month
Regular readers may recall the Frank Whittle biography that got near top marks here back in 2007, the Discovery Channel documentary based on it that I rather raved over, and the expanded DVD version. In telling the story of how the jet engine came into being, very positive mention was made of the parallel, pioneering work done by Hans von Ohain in Germany. This raised my curiosity. History tells us thet von Ohin's engine flew first, but had he known of Whittle's patents, or did he approach the problem from a different direction? A bit of a search on Amazon revealed that an English language biography of Hans von Ohain was available, so the book was ordered and is the subject of this month's New Books, as I've finally managed to finish it (and yes, it's going to loose stars because of the effort required ).
The book is Elegance in Flight by Margaret Conner, American Institute of Aeronautics and Astronautics Inc, Virginia, 2001, ISBN 1-56347-520-0; hard-bound with 286 pages, illustrated by an adequate number of black and white photographs and line drawings. The book has 20 chapters and five appendices which provide about what you would expect in an biography, namely an account of Hans' life from cradle to grave with some technical details in appendices. It is neither footnoted, nor end-noted, which some will see as a plus, although a "Resources" chapter provides a list of the books, articles, and documents consulted during the writing. Overall it's light reading that varies between very entertaining, and a bit rambling encouraging skimming.
The first twelve chapters take place in Germany recounting von Ohain's family, education, and his work on jet engine development done for the Ernst Heinkel Aircraft Works up to the surrender and his subsequent work for the American Navy and ultimate recruitment to continue his work in the USA. The remainder of the book tells of his life in America, marriage, and accomplishments. In many ways, these latter achievements are more remarkable that his jet engine development work, but to me, the narrative lacked the force and cohesiveness of the first part.
So overall, I liked it and now feel I can place the achievements of von Ohain and Whittle in perspective, sequence, and history. Both accomplished amazing advances. Von Ohain's appear to have been technically superior, but he did not have to overcome the hostile environment Whittle faced in his "backers". Both lived at the end of the period when great technical advances could still be made by individuals. This is not to infer that today's scientists are any less talented. It's merely that the bar has been raised so high by those that came before, we no require teams of talented people to move it a bit higher. Hans von Ohain was a brilliant, gentle man, with a good sense of humor. I'd have loved to see the look on people's faces when he told his "German joke" as recounted in the biography. Very non-PC, but sure appeals to me! Elegance in Flight is available from Amazon and I rate it at four stars .
Engine Of The Month: Sky Shark
Once again, Adrian Duncan looks into a rare subject, the Sky Shark 49 from Japan of the early 1950's, which he dubs great lump of a thing. Smarting, but undaunted from the ACE blunder, Adrian and I feel we may be on safe ground with this one because he has just about the only one left in existence! But truly, if you can provide any extra information, or can correct any inaccuracies, we want to hear about it.
Tech Tip of the Month
This month, not so much a tech-tip as a cop-out. We started (and ended) the Editorial describing a better tool for plunge knurling prop drivers. The ACE Madness piece showed how to machine a tricky bit on a small casting. And the next and last news item for this month concerns ways of making cam shafts. So consider you can consider all of those tech tips, I can call this rather large issue done and get it posted before sundown on the dead-line date.
The Jig Is Up
One of the things I like about running this web site is the cooperative approach the "traditional" print journal editors show to it. Being free and monthly, less open minded people might see MEN as competition, but not guys like Tim Dannels (Engine Collectors' Journal), Mike Rehmus (Model Engine Builder), and Malcolm "Nemett" Stride (The Model Engineer). We all help each other, which I for one find most satisfying. As a 'frinstance, Malcolm noted a recent article in the ME on IC cam making credited a certain jig to the late Bob Shores which Malcolm knew to have been described by Egdar T Wesbury in his 1947 series on the Seal. Wondering if this was the first use of the method, Malcolm cunningly decided that an email to us here was quicker that wading through thousands of back issues of the ME, and I was please to be able to tell him that as far as my past research has been able to uncover, the first description of the jig was in an article entitled
Notes on the Design and Production of Cams. Part 1 by Dennis H Chaddock that appeared in ME No 1935, of Tuesday June 9, 1938 (p543). The Bob Shores' fixture was published in an article called Cam Cat which appeared in issue 76 of SIC Magazine, Aug/Sep 2000 (p28). And no, I am no kind of encyclopedic resource. My mind is like a sieve for coarse gravel, but knowing this I record things and place them where others can find them—namely right here! If you want to go to the Feeney Series, page 7, you'll find no less than 9 references to significant contributions for the art of making cams for model engines. There are more, but this is a good starting point.