Model Engine News: July 2013
Threaded Inserts Redux
Another Barstock Mate
ML7 Chip Tray
Another Clan Running
Model Engine eBooks
New Books and Magazines This Month
Engine Of The Month: Hill 3.4
Tech Tip of the Month
Unless otherwise expressed, all original text, drawings, and photographs created by
Ronald A Chernich appearing on the Model Engine News web site are licensed under a
Creative Commons Attribution-Noncommercial-Share Alike 3.0 License.
Well that was a busy month! First, Adrian and Lorna Duncan arrived from Canada for a visit to Australia, including a couple of days here in Brisbane and a great time was had by all. Adrian and I discussed model engines, control line flying, workshops, music and other things. We also got to jam together a bit and went flying with the newly completed Bi-Slob, more of which later. To me, one of the most exciting things to emerge from Adrian's visit was the possibility of producing plans for a rather historic and potent 3.4cc combat diesel. The engine is our current Engine of the Month feature and if we can work it out, the plan set will add another nice high performance, bar-stock diesel as a companion to the Naylon Viper, which has proven to be a very popular plan with builders.
Now, the Bi-Slob. The best laid plans, etc. Instead of taking the two weeks initially projected to complete, it took Van and I four, but the result was worth it and has been more fun than we've had for ages. It also provided more surprises to our fellow club members at the Thunderbirds MAC than they've had in ages, too! Our test flights were conducted during Adrian's visit and we were a bit lucky in that Adrian had seen one fly before, so knew how the trick of entry to the hover was most easily executed. He was duly therefore given a turn at the handle and managed to slow the bird down to almost nothing by executing a sequence of near vertical climbs and dives, washing off speed, until coming into a climb from a dive pull-up, the aeroplane just plain runs out of airspeed, and hangs on the prop. The gigantic wing area, coupled with the very generous fin and motor offset combine to maintain line tension, and as we found the next weekend, with the Fox 35 set just right, the Bi-Slob can be made to hover almost indefinitely into wind, or by entering the hover down-wind, will gradually settle gently until the tail wheel contacts the ground, at which point it tips forward onto the main gear, accelerates, and takes off again, all under full control, all the time, even if it does not look like it, and completely without any third line control of engine rpm! Both Van and I have mastered this trick now and have hung the 'Slob on the wall, for special occasions.
From all that, you can speculate that I'm feeling a lot better, although I still have no appetite to speak of. Getting the pain under control (more morphine!) has helped, as has the radiotherapy on the lumbar tumor which seems to have broken up whatever was pressing on the nerve cluster, so life is good until next time. Guys, take advice from me on this: have your prostate checked regularly. Once it's in your bones, there's no cure, and it will cramp your style. The photo shows Ron and Adrian in the Model Engine News Library, fondling a pair of engines we each admire. Out of view are the rest of the shelves, covering another two walls, and a closet full of boxes containing some "overflow".
Moving on, with the Bi-Slob completed, I've turned attention back to the Grumman Guardian (Brodak profile model), which has been sitting awaiting final assembly for almost a year. The hold-up had been a last minute decision to have the rudder deflect when the hook was dropped, without a clear plan in mind as to how this might be best achieved. Well, this has been solved, implemented, and the first coats of balsa filler applied. Spraying is not far off, which will clear the building bench. I'm now thinking of a Keith Tostle FW-190 (or TA-152, if you prefer) stunter as the next project. With dread memories of how I totally lost control of weight during the finish process on the poor old Cardinal, I intend to keep the weight under constant observation this time round. For why I need to be reminded of just how important this is, see the April 2009 issue.
How about a two-stroke glow plug ignition engine which runs on petrol (gasolene), not methanol? The release of such a beast was brought to my attention by David Burke, Head Honcho at Taipan specialists, Adelaide Aeromotive. This concept is interesting for a number of reasons. If you read our piece on Ray Arden, you should recall that the glow-plug fits hand in glove with the introduction of methanol (aka, "hot fuel"), with the catalytic reaction between platinum and alcohol forming an important part of the partnership. Now we have an engine which seems to break the rules, as the manufacturer claims it produces more torque than their equivalent "nitro" (uggh; shudder; gasp; blasphemy...) engine. They also claim better fuel economy.
The concept of the "glow plug" does indeed date back as a cold weather starting assist on full-size diesel engines, so there is some kind of precedent. As to the makers' claim that "[this] exciting new development in engine technology should radically change the current model airplane market for the next decade as other manufacturers scramble to catch up", the greatest leap I see here is the new high reached in outrageous advertising copy hyperbole. But maybe I should not be so cynical. The company which produces this engine is the same one making the excellent little "Big Mig" and AME 1/2A engines, after all.
Granted, gasoline has a higher calorific value than methanol (see the table in FCB Marshall's Model Engine Fuels dissertation). The trick is ignition. The review referenced by the advertisement mentions a "Turbo Plug" without saying what this might be—a thick ni-chrome coil, or something like the old Fox "Miracle" plug perhaps—something to retain heat, one expects. Digging in the engine parts on the web site, we find the OS P3 specifically listed as the plug for the GX 40RC. This is a "hot" plug (ie, intended for low, or no nitro content fuels), with a tapered seat (the "P" prefix) which says more about the head thread geometry than anything else. Apart from the seat, there is nothing special about this plug—it's not even 4-stroke rated.
So, interesting, no? Ignoring for the moment the comments made in this month's Tech Tip, I also find myself strangely curious regarding what the maker has set the geometric compression ratio to . With the current cost of methanol and nitromethane, the use of pump petrol has a certain appeal, although as DB points out, gasoline may contain toluene (methyl benzene), and the review implies that the use of an electric starter is essential. As to the rest of the claims made for the GC 40RC, the over the top tone of web site text makes this little brown duck wary, but I'd like to believe...
Threaded Inserts Redux
In the December 2012 Tect Tip, we looked at a fool-proof way of inserting threaded inserts for engine mounting, and other perverted past-times. I knew when writing the piece that I really should include a table giving the recommended size for counter-boring, but lacking data for all the possible insert sizes, I chickened out and was delightfully vague on the subject. Having run out of 4-40 inserts, I placed an order on my preferred supplier, Micro Fasteners, of Lebanon (NJ), whose catalog contains all the required data, so our page on How To Install Threaded Inserts has been updated with the fractional and metric counter-bore diameters of inserts from 2-56 to 1/4-20, and all ports between. Now, why Micro Fasteners and not someone like Du-Bro? Well, Du-Bro charges about $2.05 for four (4), while Micro Fasteners charges $4.40 for twenty (20). Do the math...
Another Barstock Mate
The extrusion which David Owen commissioned for builders of his Mate 2cc DIY Diesel is long gone, but as several model engineers have found, this is not a show-stopper for anyone determined enough, and not afraid of a bit of swarf. The latest Mate, seen above, comes from Ed Holly (Australia). After a few trials, tribulations, pistons and liners, Ed's Mate is humming along nicely. Even better, Ed prepared a "documentary" which shows how he went about making the case, amongst other things. This is in pdf format, so be prepared for almost two megabytes of download if you click the thumbnail. Ed's next project will be a Mills 1.3 Mk I from Motor Boys plans.
ML7 Chip Tray
A new offering for the leigon of orphaned Myford ML7 lathe owners is a neat chip tray from Hemingway Kits (UK). As chip trays go, this is the Rolls-Royce version, with a drain plug for coolant reclamation, a forward felt bed wiper, attachment locations for coolant towers, DTI posts, and vinyl grinding covers, which can be fitted in seconds. The casting fits to the saddle, ahead of the cross slide, using the tapped hole already present for the following steady, and Hemingway says it will pass under a 5" diameter chuck. My only reservation about the device would be in regard to the latter claim when the jaws are at close to maximum grip capacity. This extends the chuck diameter considerably, as I know from past experience when they've clobbered my own chip tray with a large and unexpected noise, plus a shower of chips, coolant, and bad language. But as my tray is folded and soldered from sheet brass, and held in place by a magnet, no great harm was done. A casting might not fare so well, so if you fit one, be cautious. Nice idea, though...
Another Clan Running
Small diesel engines represent as much of a challenge as some larger multi-cylinder projects due to the high degree of precision required to get the fits of piston and liner just right, not to mention a crankshaft and crankcase which offer low friction, but retain primary compression to ensure adequate transfer. I continue to be amazed at the number of model engineers who decide to take on the Clanford Clan, and refuse to be beaten by it. The latest Clan conqueror is Mike Walker (USA). Mike overcame fuel draw problems and machined a very light taper into his cylinder. Following the "set to prop at 10 to 4, and hit it" technique, his Clan turns a Graupner 4.75x2 plastic prop at 9,200 rpm. He rates the overall project as very satisfying, and we'd have to agree!
Just what would be the collective noun for the ML Midge? Midgii? a Buzz of Midges? Whatever, the world's supply of them increased by one this past month with this one build by Ross Purdy (NZ), to Motor Boys plans. Ross reports that his Midge starts easily, even if it is no power house. Well, that is so, but unlike some, the engine is a danger to custard and rice pudding skins, and will certainly power the little Vic Smeed Tomboy which Ross has planned for it. Originally a sport free flight cabin model, the little Tomboy is today an ideal subject for an R/C park flier, and let's face us, the prospect of a free flight retrieval diminishes exponentially as years increase...
Model Engine eBooks
It had to happen. A reader has alerted me to a commercial site which is providing a series of eBooks on model engines, and aeroplanes. The books are not expensive and can be purchased through Amazon, though I've no clear idea as to the content, nor quality. The site, which from the URL, I gather is called the Model Engine Trading Post, is also a trading post for model engines (surprise, surprise). It states that all engines offered have been run and that a video of a test run has been recorded and is available. At the moment, they are offering some original Gotham Hobby Deezil engines, rebuilt as required to run. There is nothing whatever wrong with the old Deezil design, it is quite sound. Like AHC's Thor, Genie, and GHQ, it was the implementation rather than the design which led to the poor reputation, so one of these may be just what you are looking for, although I think I'd prefer one which did not run—that being far more representative of the type! Beware of the "VCR controls" at the bottom of the page. They launch some (to me) extremely annoying noises! Your mileage may vary.
New Books and Magazines This Month
Woohoo! It's that time of year again: Tim Dannels has completed yet another bound volume of the Engine Collectors' Journal (ECJ). The new one, Volume 37, collects ECJ issues 211 through 216. This represents forty-nine (49) continuous years of publication for ECJ. Tim's first issue was dated August, 1963, so is he approaching the 50th Anniversary Issue? Well, that depends on how you count things, doesn't it? I'm of the school that says the twenty-first century began on January 1st, 2001, so ECJ will need to complete the next volume before the corks can start popping. But regardless of how you count things, that is a lot of issues, and a lot of effort, totaling up to a lot of enjoyment for model engine lovers everywhere.
ECJ is available in two forms. You can take out a six (6) issue subscription for US$20 ($22 for Canada, or $25 for Rest of World), or you can order bound volumes of six isues each with prices ranging between US$21.00 for the later volumes, down to $7.50 for the very early ones, starting with Volume 2. Volume 1 was something else and can be read on-line through the Model Engine Collecting web site. The breadth and depth of coverage is enormous, with material directed at too many facets of our hobby to list. I've said many times that dedicated model engine fanatics should have a full set of ECJ on the shelf, and I continue to stand behind that assertion. Just leafing through an old volume will always stir the creative juices.
So what is in Volume 37? I've only had it for a week as I write this review, but so far the stand-out for me has been David Axler's review of the America's Hobby Center (AHC) Thor, and Genie slag sparkies from Issue 217, the Madewell Twins (Issue 216), and the Aero 35 (Issue 216, again). Other highlights are articles on the Dan Calkin ELF series, an Atom Twin (which I did not know existed), and various types of Fox and K&B engines.
The magazine itself exhibits some change with the occasional inclusion of full color images on pages other than the cover. Each issue contains fourteen (14) pages, including the cover. The quality of the photography and other images is worthy of note, with the praise going to the ECJ contributors, and Tim's skill as editor, page-setter, production manager, and publisher! Obviously, I'm biased, but I'm giving five stars to ECJ, Tim, and all of the talented folk who have contributed material to Volume 37 and look forward to the next Volume .
Incidentally, Tim says that subscriptions have been on the decline of late, as has the numbers in engine collecting in general. On the other hand, engine builder activity is growing, though getting those builders to pay for a dedicated magazine has been an uphill battle, as Bob Washburn found with Strictly Internal Combustion (SIC), and Mike Rehmus confirmed with Model Engine Builder (MEB). Mike continues to fight the good fight with a robust on-line offering, as do I with Model Engine News, even if I cheat a little by giving the thing away. Where from here? My sad guess is that when Tim, Mike, and I decide to pull the pin, that will be it. Engines, collecting, and building will not go away any time soon, but given the trend towards instant gratification, coupled with the amazing volume of things out there competing for our collective leisure time, I can't see a bright future on the horizon. So enjoy it while you can, and support efforts like ECJ and MEB while you can too.
Engine Of The Month: Hill 3.4
Fans of obscure, British, 3.5cc combat diesels, rejoice! This month we have an in-depth review of a little known but potent engine which died when the contest class it was designed for disappeared. If you were alive, awake, alert, and reading Aeromodeller cover to cover in January, 1960, there is a chance you may have heard of the beast. For the rest of us, me included, it may come as a bit of a surprise—although a brief mention of it did appear in the March 1996 issue of the long-defunct publication, Model Engine World. Adrian Duncan has managed to get his paws on an example, and dug up contacts old and new to bring us the full story. Even better, we plan to fully document the design as a MBI Plan Set in the near future as, despite appearances, the engine is bar-stock and highly suitable for home-shop construction, making a fine companion to the Naylon Viper, a completed example of which we saw emerge from the workshop of Charlie Stone, last month.
Tech Tip of the Month
Our news item last month on Spark Ignition was well received as a Tech Tip, which it probably should have been. So by including a reference to it here, readers who are paging back and forth by Tech Tip cross-links will at least blunder across it, if they have not already. Jan Huning, one of our regular readers (and contributor in the shape of the Atom Minor Mk III construction series), went so far as to implement to transistor assisted version and reports a most gratifying spark across the plug electrodes, and none whatsoever across the points, which is a good thing. Jan did however discover—the hard way, as if there were another—that power transistors electrically connect the collector to the case, so if you connect that to a heat sink, keep said sink away from the engine case, or bad things will happen. The correct solution is a transistor mounting kit and silicon grease. The kit electrically isolates the transistor case, and hence the collector, from the heat sink, while the grease connects them thermally. But at the power levels involved with your typical three volt ignition coil, you can probably dispense with the heat sink anyway. If not, as Jan observed, just as well the transistors come in five packs!
The piece last month on Geometric and Actual Compression ratios, was less well received, with Steve Rothwell rating it equal in importance as discussing how many turns to open the needle! I can't disagree—and I love Steve's comparison. There are so many variables involved, full qualification would waste pages to no great effect. Still, as a statement of policy we decided we had to clarify our stance, which we have.
Seeing as how we've mentioned Steve Rothwell, it seems a good opportunity to remind readers that Steve is making some very nice accessories for Team Race fliers. The photo shows his superb needle valve and spray bar assemblies, with Tee Dee style venturis available for MVVS, Nelson, OS, PA, and Oliver racing and combat engines. He also has fuel cut-offs, and mounting plates. You (and I) have missed the chance to grab a Rothwell engine, but they do still appear on the used market, from time to time.
This section is intended to alert you to little things that are hard to expand to a full news item, or cunningly wind into the Editorial, but are worthy of note never the less.
- New information has come to light which strongly suggests that our ROC is a Fuji. Adrian is looking at ways to address this, but it appears that the best solution will be to purge the ROC piece altogether and wind the information into the Fuji Story, somehow. We gat angry with ourselves when we present misleading, or wrong information, but if we waited until there was no uncertainty, nothing would get published, so please accept our mia culpas and know that we do try...
- Around the start of the month, we received three rather alarming reports, all from the UK, that parts of Model Engine News were redirecting to porn sites. This, I assure you, I take very seriously, and following a previous hack of the MEN server to send out spam, I've implemented a host of precautions, preventatives, and alerts. None of these triggered, so it seemed the MEN content and server were not the cause. My ISP investigated and we can only conclude that it was a brief hijack of a router which was to blame. The fact that it was brief, and geographically isolated supports this theory. Still the price of peace being eternal vigilance etcetera, please don't hesitate to report things like this. I enjoy my porn as much as the next guy, but in its place, and this is most definitely not the place!
- The little Tech Tip How To on Cooling Fin Cutting contained a tiny math error which may have confused readers since it was created in 2004! At last one was brave enough to query the 0.002 that was missed when I added 0.056 to 0.025, and got 0.079. The text now reads 0.081. Better late than never, I say!