Model Engine News: June 2013


Special Features:

   How To Wire Up A Sparkie
   Otherworldly Watzit
   Coles' Power Models Update
   Ageless Sleeve Valve Progress
   First Plans Built Viper
   CMM Level 5
   Full House

Regular Features:

   Editorial
   New Books and Magazines This Month
   Engine Of The Month: ED Pep
   Tech Tip of the Month
   Briefly Noted
   Standard Stuff
Creative Commons License   

 

Editorial

Thanks to all who have written this past month asking after my health. It has been a bad month with pain levels I've never imagined before. The good news is that the radiotherapy may be having some positive effect and I can now stagger around in comparative comfort. My doctors are naturally concerned about this and have placed me on a cocktail mix which has the effect of removing the edge from both the pain, and from reality! So if some of this month's ramble does not make sense, let's be generous and blame that.

All that aside, how did we go with the bold objective, self-imposed last month, of building a new model in two weeks? Well, we sort of failed, but not by much. Everything is complete apart from painting the wings and gluing them to the fuselage (and hooking up the flaps, and plumbing in the engine, and...) Actual assembly ran to schedule and it was fun to build a non-serious model for a change—something there isn't even a competition class for. Several readers wrote to say they'd seen Bi-Slob's fly and that we were in for a treat. Adrian Duncan arrives here in Brisbane (Australia) for a visit in the first week of July, so the plan is still to take him out to our local control line field with the Bi-Slob for some fun flying, if it stops raining .

How To Wire Up A Sparkie

Last month, a reader emailed asking how to wire up an old spark ignition engine he'd acquired. My first thought was that the question was rather basic, and my second was to mentally slap my own wrist, because the only "dumb" question is the one you didn't ask, and that one is perfectly legitimate. Going for a record, I then followed up two thoughts in the same day with a revelation: nowhere on this very, very large website dedicated to model engines, do we explicitly tell how to wire up a spark ignition engine! This has been corrected, with a new "How To...", and a cross reference in the Frequently Asked Questions for MEN. Click the link for the new How To Wire A Sparkie Page. It's only a bit basic if you already know the answer, and for those who already know, we include a suggestion for a source of authentic vintage hookup wire which may surprise and delight you.

Otherworldly Watzit

How to introduce this one? How about, It's a Watzit, Jim. But not as we know it... The pictures of this unusual creation were sent to us by the new owner, following his successful eBay bid on the thing. At this time, we are making no public speculations and are merely asking that if you happen to know what it is, we'd appreciate hearing from you. There are six pictures of it on the new Watzit Page, along the the text which described the auction. Sadly, I was not quick enough to pull the plug on my Skept-O-Meter ™ before reading the description, so the needle is now permanently bent.

Coles' Power Models Update

Last month, we mentioned reports that the website of Coles' Power Models, of Warren TX, was not responding. Thinking outside the box, our good friend, Lee Hodgson, who runs Ageless Engines, phoned Ken Roberts at Coles using landline technology. Ken explained that while there had been a robbery at his business, and that many castings and raw material had been taken, he is still in business. Thinking about this, you can see how reliant we have become on the Internet, and how the sudden disappearance of a web site (there dreaded 404 response) can quickly lead to harm. All that said, the web address we have for Coles' is most definitely no longer responding, so if you are located in the US, a phone call to them on (409) 547-3400 should solve the problem.

Ageless Sleeve Valve Progress

On the theory that no good deed should go unpunished, I'll thank Lee by mentioning that progress on his sleeve valve radial has reached the stage where he is chasing down cures for pressure leakage past the head rings, over the top of the sleeve, and out the intake. So in effect, the leakage air is going against the intake airflow. Lee has also done considerable development work to lower the compression ratio, change the sleeve timing and improve the seal rings in the head. Development progress is slow but steady, with the engine fully assembled and firing. Lee will not be releasing drawings until he has solved all the problems and is confident that the engine can be successfully reproduced by others. You can see more pictures of progress on the Ageless Engines website.

First Plans Built Viper

The Naylon Viper seen here is the work of Charlie Stone (Australia) and is, as far as we know, the first example finished from our Motor Boys plan set. The plans themselves were drawn from sketches and an example built by Motor Boy, Eric Offen (UK). As you will read in the Naylon Viper page, there are two different versions of the Viper, differing in the area of the liner and head. Charlie has chosen the Oliver-like head for his engine, and reports that his Viper starts just like his Olivers, which is to say, very easily. For more images, visit the Gallery.

CMM Level 5

In the software engineering world, "CMM" stands for "Capability Maturity Model", which attempts to measure and quantify the ability of a company, or team, to repeatability deliver high quality work, on time, to specification, and within budget. The ranking uses a scale of one to five, where five is fully mature in every aspect, and one is "a chook with its head cut off". I have to look at this photo of Tug Wilson's workbench and say that if there were such a thing for model engineers, Tug would definitely be a five, where excellence happens as a matter of course, all the time. To find out what all this work has gone to produce, visit Page 19 of the Engine Gallery..

Full House

Even before Les Stone (USA) was invited to join the group, he had made serious inroads into building the engines depicted on the cover of The Motor Boys Plan Book. Well Les completed another engine this past month which brings him to full house as regards the cover photo, as arranged originally by Bert Streigler. The new engine is the striking one with the red cylinder—a roller bearing, piston ported, 0.192 cuin sparkie of 1938 called the Trojan Jr. For more photos of this engine, visit the Les Stone Tribute Page.

New Books and Magazines This Month

Not much new in the library this month, but a minor clean-up of the disaster area I call an office did uncover a magazine I bought much earlier this year and fully intended to review, before it was accidentally buried by an avalanche of other papers. So, better late than never, we have the January/February 2013 edition of an old friend risen from the grave—Aeromodeller! Rumors of a re-animated Aeromodeller had been circulating for some time, to a mixed reception. Many of us will have the fondest of memories for the old rag, and some viewed a resurrected version with some trepidation, thinking that it might be best to simply remember the good old days, rather than revisit them and risk disappointment. All I can say, on the basis of a single issue so far, is rest easy. Publisher Alan Harman, has done a magnificent job with the first issue, or should I say, "Issue 919", as the new follows on the numbering from the old.

The table of contents shows four major headings: Features, Technology, Departments, and Vintage & History. The first new issue also contains contains a wonderful bonus sure to delight historians, a reproduction, pull-out copy of the very first issue of Aeromodeller, which carries the date, November, 1935. It is interesting to read the Introductions which set out the aims and aspirations of the two publishers, one set when model aeroplanes were in their infancy in an air-minded society; the other in a world where autonomous, electric powered quad-copters might supply ten minutes of diversion from the tech-heavy world that seems set on instant gratification and fads. But craftsmen still exist, as we well know from the subjects which grace these pages month after month, and I sincerely hope that the new Aeromodeller finds its place catering for those of us who like to build as much as they like to fly, and draw their enjoyment from non-radio controlled models.

By now, you've probably guessed I'm going to give the new edition a Five Star ranking, even though it's early days. Part of the reason for this is intangible, being the feel of earnestness to do their best and get it right that I sense in all aspects of the publication, from content, through presentation, to marketing. Traditionalists can order a subscription for postal delivery, six issues per year. If on-line reading is more your thing, you can get versions delivered electronically to your PC, or the Apple or Android portable device of your choice. For full details, and more about the magazine contents, visit the new Aeromodeller website.

Engine Of The Month: ED Pep

Adrian has a provocative sub-title for this review, Forgettable Fiasco, or Successful Failure?, which sums it up, really. This is a bit sad as the engine itself is one that I've always thought was rather cute. Some years ago, I decided I simply had to find one to add to my collection of ED engines. This proved remarkably difficult, and I eventually had to settle on a "De-Za-Lux" (I kid you not) ZA 92 as close enough. Where and how this fits into the picture is all detailed in Adrian's new ED Pep review.

Tech Tip of the Month

This month's "tip" is more along the lines of an Editorial Policy statement regarding compression ratio. This is one of the many little things in a model engine—or any internal combustion engine for that matter—where a small change can have a dramatic effect. Whenever you see a compression ratio mentioned on these pages, it will, unless clearly stated otherwise, be the Geometric Compression Ratio, even though on a two-stroke, this valve is only vaguely connected to the effective compression ratio (follow the link to our Frequently Asked Questions section for details on the difference between the two).

Why? Tradition, mostly. The CR is not a parameter you often seen in model engine reviews, but when you do see it, it is always the geometric compression ratio, so the use the actual compression ratio would lead to confusion with what other data is out there. There's no argument that until the exhaust port closes, the mixture cannot compress, so what we are quoting is not the real compression ratio, it's just a measurement that can be used for base comparison.

To add insult to injury, compression ratio is not something that can be considered in isolation either. The story below, from 2-Stroke Glow Engines for R/C Aircraft: Volume 1, by Dave Gierke, really rams home this fact.

Racing without Nitro (Dave Gierke)

A few years ago, I was competing at a local Quickie 500 pylon race. Typically, everyone fuels their airplanes from a common supply provided by the contest organizers. Quickie fuel consists of 15 percent nitromethane, 20 percent lubricating oil and the rest, methanol. Just before a heat race, I went to the fueling station to tank up, but the gallon bottle was empty, so I walked to the truck and grabbed another jug and proceeded to fill the tank. At the starting line, the engine responded strangely to the needle-valve adjustment. My first reaction was, "It acts like a blown plug" (damaged wire element). Since there wasn't time to check out the problem, I flew anyway.

To my surprise, that flight resulted in the fast time for the contest, up to that point. When I returned to the pits, someone informed me that I had opened the wrong bottle of fuel! I mistakenly used FAI fuel, which contains no nitromethane—only methanol and lubricating oil. No one could figure out why my engine ran so well on fuel that had less power potential. After thinking it over, I decided that the engine was over compressed for the standard Quickie fuel, so I put a shim (gasket) under the head. On the next flight, I reset the fast time—using the correct fuel!

There are practical limits to the rate of pressure rise. If the rate is too high, forces on the piston become hammer-like, causing rough operation. These excessive pressures can also lead to detonation. Changing fuel or the heat range of the plug will often cure a rough or hot running engine.

If we need another story, back in the 1960's, Australian control-line stunt fliers could never understand why the Americans raved over the Fox 35 as THE stunt engine. It was hard to start, hard to tune, and rather gutless. It was also designed to use fuel with nitromethane in it, which was almost impossible to obtain in Australia back then, as a glance at the geometric compression ratio would have told us, if we'd known about such things. It was not until decades later when nitromethane became available to the average modeler that we discovered what we'd been missing in the Fox 35—when run on the fuel it was designed for, it was the stunt engine our American cousins had told us it was.

So, the take-away from this is the value you'll see quoted for compression ratio in MEN will always be the Geometric Compression Ratio, unless we explicitly state otherwise. Broadly speaking, it tells what type of engine we are dealing with—spark ignition, glow-ignition, or compression ignition. In the case of glow ignition, it can indicate how much nitromethane, if any, the designer intended the engine to run with.

Briefly Noted

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.

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