Model Engine News: January 2010


Special Features:

   Model Engineers' Workshop Archive Online
   Another Model Engineering Website
   New Home for NE15S
   Tarantula
   Pro-Motion Video
   Ivan Rogstadius: Swedish Model Engine Pioneer

Regular Features:

   Editorial
   New Books and Magazines This Month
   Engine Of The Month: Taipan 2.5 S64PB
   Tech Tip of the Month
   Standard Stuff
Creative Commons License   

 

Editorial

One hundred and twenty-six days poor old Brisbane went without rain this spring and summer—or so the voice on the radio said. I was not counting; I just knew it was bloody hot, and bloody dry, mate. Then, just three days before Christmas Day as my partner's number three son arrived from London for a visit, the heavens opened and it's been raining every day ever since. We should patent and license him. Even better, he came bearing a box of cast-iron castings so a great time was had by, well, me, mostly .

2010, already! So what can be said about the past decade? It would be easy to wax philosophical on the so-called "naughties", so I'll refrain and you can make up your own tales of joy, woe, and how much fun air travel has become. Now some lunatic sets fire to his crotch during finals into Detroit and we honest citizens can look forward to measures guaranteed to increase our frustration and diminish our freyed sense of modesty. Who's winning here? On the brighter side, Australian airline passengers were told that they could can once again include knitting needles and nail clippers in their cabin hand luggage. Truly, our cup runneth over, or do I sound even more tired of it all than usual? Probably, so just as well there are good model engineering things happening to offset the rest.

I have stacks of good stuff queued up for MEN in 2010. Finding the time to format it all is the trouble as usual. I'd hoped to include a bonus plan set for Members nin January, but time, heat, and a couple of good books got in the way. But at least it's in the can, as are some wonderful new watzits and unusual engine subjects. I think we are all going to have a terrific time in the shop in the next twelve months, so let's get down to it with news of stuff happening on line.

Model Engineers' Workshop Archive Online

Issue #159 of Model Engineers' Workshop (MEW) arrived in late December with a notice on the Editorial page that back issues from #1 to about #120 have been digitised and made available online. Woo-hoo! Well, almost. There is a little catch which reminds me of the futuristic cuss-word "invented" by SF writer, Robert Heinlein: TANSTAAFL. Access is by subscription and that will set you back £29.00 per year. That's about US$47, or A$52.

Initially, I had mixed feelings about this, but overall I now think it's a Good Thing. I've seen single, early issues of MEW sell for about the subscription price on eBay, and as The Library has a nearly complete set, I sort of viewed them as an investment. Ready availability of digital copies—and they will leak out—devalue my set. But they are hard to track down, so making them available at a reasonable cost is a service to the hobby as well as a money-spinner for the publisher. You do not have to be a MEW subscriber, but current subscribers also have to pay for access. That is wrong. Existing subscribers should get a substantial discount at the very least, but I would say that, wouldn't I?

Another Model Engineering Website

Somehow I'd missed this one, but there's so much stuff coming (and going) on the Web these days. Model Engineering dot com is a web magazine edited and published by model engineers with the aim of promoting the hobby and presenting reports of shows, events, news, and ideas for your workshop or next project. Although UK based, the content is international. There is no significant IC content at present, but editor David Carpenter is looking to address that in the future. Well worth a look.

New Home for NE15S

The Hawk Eldon and Nemett's prototype NE15S have found a new home and the proud new owner has emailed to ask that we let prospective builders know that photographs can be had on request to Digitron@btconnect.com. This is just the engine itself, not the drawings rights. Those are tied up in Malcolm's estate and I'd not expect to see them available again any time soon, which is a pity as many fine examples were built all over the planet. By the way, issue #4361 of the Model Engineer ran a very nice tribute to Malcolm in which I discovered that he had worked for the (once) British main-frame computer giant, International Computers Limited (ICL). So did I, though in Australia. Wish I'd known that while he was alive—I'm sure we could have traded even more names and stories.

Tarantula

There are a surprising number of subjects that just refuse to lie down. One which I've been asked about several times over the years if the Tarantula, a nine cylinder two-stroke radial based on Cox 049 parts, conceived, designed and built by John V Thompson in the latter part of the 1970's. Some details regarding the engine appeared in the long defunct magazine Scale R/C Modeller, and as The Library contains a yellowing copy, and since another request for information about the engine came in during December, the text has been turned into a Tarantula Page. This represents all the information we have. Mr Thompson sold plans for the design at the time, but none are known to survive today. As usual, we welcome any more information regarding this engine. You should also look at Page 8 of the Gallery for similar work carried out by Ralph Barnette.

Pro-Motion Video

Back in the June 2009 issue, we mentioned the US Model Engine and Model Engineering show being hosted by the Bay Area Engine Modellers. I've received an email from Steve Hazelton of Pro-Motion Video (gotta love the name) advising that he has a DVD of the 2009 show available for about $US20, plus shipping. I've not seen it, so can comment no further. If you are interested, email Steve at pro.motionvideo1@gmail.com. If you'd like to see stills from the show, Tom Keliher has a gallery on fototime.

Ivan Rogstadius: Swedish Model Engine Pioneer

Over the years, Model Engine News has tried to document early model engine pioneers and their works. For this we rely mostly on research into such written accounts as can be found. We think the results are accurate and always try to quote our sources so others can verify the findings, or form their own impressions. Recently, we came across an article in a 1944 magazine describing the first "diesel" model engine detailed for home construction in Sweden. In seeking a translation of the pages, we were delighted and astonished to find out that the designer and author, Mr Ivan Rogstadius, was alive, well, and happy to discuss his engine. So click here to read about how Ivan's engine came to be. We also have translations of the article describing construction of the engine and another recounting its first flight. Thanks go to Lars Gustafsson and Adrian Duncan for making all this possible.

New Books and Magazines This Month

Christmas arrived just a little bit early here this year in the form of Maris Dislers' magnum opus on the engines designed by Australian legend, Gordon Burford. Maris is a noted Australian competition flyer who, like Gordon, hales from Adelaide, South Australia. So what could be more natural that he (a) develop a love of Australia's own Taipans, Glow Chiefs, Sabres, etc, then (b) decide they needed to be definitively documented. A fine goal, which quickly got out of control as Maris elected to test as many examples as he could, complete with BHP/Torque curves (using calibrated propellers) so meaningful cross-comparisons under similar test procedures could be made. As his research soon discovered, Gordon not only produced a new design every year or two, he favoured small production runs with frequent incremental changes in detail between runs of the same model: good for customers who benefited from a constantly improving design, but a nightmare for the model engine historian. Then there was the failure of the original plan which had text and photos being handed over to a mysterious "someone" for layout and printing. We've known for years that Maris' book was coming Real Soon Now; the problem was living long enough to enjoy it!

Well, the wait is over and the first batch have gone out to the many Admirers of Gordon's engines who helped provide information and loaned Maris treasured examples for testing. Being one of those, I have my own copy and can say the wait was worth it and that Maris deserves all the accolades he receives for a difficult job done well. I hope he manages to make a buck out of it too, though I really doubt this was ever a real goal for him, or others who have laboured to document similar marques (I'm thinking of John Brown's Dan Calkin and His ELFs, or Jim Dunkin's Dennymites, Drones & More, and others).

The purpose behind the book is to answer for once and all the question of "what Burford engine is that?", not to mention what needle valve and prop washer should it have. The motivation is, I think, somewhat different and I was taken by Maris' own Introduction where he considers the "why?" question, saying:

Why write a book about model aircraft engines? For starters, they are fundamental for keeping a powered model aircraft in the air. Also, it takes a degree of perseverance to master them and many owners have been brought to tears of frustration and despair before getting one to work properly. So there is a certain sense of achievement when the skills have been learned and the "enemy" becomes a true friend. This makes them a good deal more interesting to many of the initiated than the equally practical, modern electric motor.

Maris, well said and how true—especially so in the case of the wonderful, smelly, messy diesel that Gordon and so many more who cut our teeth on this type love so much.

Ok, enough of the congratulations already. This is not an inexpensive book. Your copy is going to set you back A$75, plus postage, so what do you get? Gordon Burford's Model Engines, by Maris Dieslers, Self-published, 2009, ISBN 978-0-646-52498-6, is soft-bound, A4 size (about 11x8), with 200 glossy pages printed in full color with over 250 superb color photos, and numerous tables. The seventeen (17) chapters cover Gordon's creations in logical groupings, all the way from the three prototype GB-1 engines he made in 1946 based on Lawerence Sparey's 5cc Aeromodeller diesel, through the quantity production years of Stuntmota, Gee Bee, Sabre, Glow Chief, and Taipan, to the Doonside collaborations with Ivor F, the high-performance Burford Team Race engines, the limited production run "Currumbin" engines like the Burford Deezil and Elfin Replicas, all the way back to the Burford-Owen GB-1 replica (an example of which changed hands on eBay in December for a mere £258). Some would say that the real gold is in the Appendicis. In the first of these, Maris describes and tables the fittings for glow and diesel engines, including color photos of all needle valve assemblies and compression screws. The second is dedicated to packaging with photos of all the different box styles—including the Bubble Pack 1.5cc diesel that introduced me to the tears of frustration and the sound of triumph back in 1957, plus copies of the instruction sheets that accompanied the boxes. The only thing missing are figures for bore, stroke, and weight.

Gordon was a prolific designer and manufacturer and generally had several models in production at any one time. The format chosen to present the story is to group the various models and then deal chronologically with the sub-set, rather than try to present the entire bewildering range in sequence. So we get separate chapters dedicated to the 1.5cc engines, the 2.5's, the Marine variants, the Glow Chiefs, the Large Taipan Glows, etc. Within each chapter, we are introduced to the progression of "official" models (to the extent such distinctions can be made), including the "failures". After describing the features and construction of an engine, Maris describes his experience running it and presents tables of prop verses RPM, together with Torque/BHP curves, and observations on the performance and handling qualities with different fuel blends, contrasting his findings with those of published tests. Where significant discrepancies exist, he looks for reasons and ranks them against performance and price for equivalent engines of the day. In all, a most thorough, methodical approach which I found entertaining, informative, and eminently readable.

You can obtain your own copy by contacting Maris by email, or by writing to him at:

Maris Dislers
76 Glengyle Terrace
Glandore
SA 5037
Australia

At 770 gm, or about 1 pound 14 oz, this is no lightweight book, and Maris ensures copies are well protected for shipment, so postage in Australia is A$10. However Maris can ship up to three books in the same packing, so you might like to club together on orders. The cost for overseas shipping varies, so email or write to Maris to find out what the cost will be to your part of the planet. Maris takes Australian postal orders, electronic funds transfer, or PayPal. Again contact him for details before ordering. Even if I was not a self-confessed Taipan fanatic, I'd still be giving this book Five Gold Stars and a Koala stamp .

Engine Of The Month: Taipan 2.5 S64PB

How appropriate to follow up the review of Maris' Burford Book with a Taipan review. For years, I've relied on aging photocopies of a series of articles by Ivor F to answer the "what Taipan is that?" question. Now I have The Taipan Reference, so I can state with certainty this must be a Mk 7 from 1963-4, except the needle is wrong, the comp screw is wrong, the head screws are wrong, and the case is not sand-blasted! Failure? No, not really, because this S63PB 2.5 is the work of David Burke (DB to his mates). You can read about it, and the "real" version on the Taipan 2.5 S64PB page, but you might first want to contact DB because as I write this, he has three more available for sale. Now I'll stand back to avoid being crushed in the stampede...

Tech Tip of the Month

I'm astounded that many model engineers are a bit intimidated by the thought of making fine male and female tapers that have to mate with each other. It's not difficult and as usual, there are a number of tricks that will produce "good enough" results, provided you know when the taper needs to be precise, rather than just close enough for government work. Tapers with an included angle of 3° or less are known as self-holding. The well known Morse, Brown & Sharp, and Jarno Taper fall into this category and anyone who has ever tried to separate a drill chuck from a JT arbour will know just how tightly such a taper can lock.

Aside: The subject of self-holding tapers is complex, depending on other factors such as material for the mating parts. I'm going to skim over it here because I want to deal with making mating tapers. Those with access to a good technical library who are curious should investigate the subject in mechanical engineering texts. A more entertaining investigation into the subject appears in Guy Latuard's Second Machinists' Bedside Reader.

Beyond 3°, tapers are called self-releasing. For prop drivers on our model engines, we generally use tapers in the range 5° to 10°. In theory, these are self releasing, though well formed tapers will probably require a gear-puller of some kind to get them apart. For these, I suggest you made a few simple D-bit reamers from drill rod, hardened and tempered to "deep straw" color. These are used to form the female taper in the driver. The male taper can be formed by placing the reamer in the headstock, then setting over the compound slide using a DTI to match the reamer. If you get 0.001" or less change over 1/2 inch of travel, that will be quite close enough for a prop driver fit. And as you are clocking the taper for the male component from the reamer that produces the female taper, it does not matter if the reamer was originally turned to precisely 8° or 8.217° or anything close. You are making one fit the other.

But what do you do if you really, truly want an accurate taper? References like Machinery's Handbook and others have tables of tapers which will quote the taper as inches per foot, or a metric equivalent. For other tapers, you can create your own using a scientific calculator. Let's say we want a taper of 8° accurate to within 0.1°. We don't need a taper turning attachment with a sine block fitting. Your average compound slide will cut a good taper over a short distance if advanced slowly at a constant hand-feed rate. Imagine an acute right angle triangle where the length of the hypotenuse is 0.5" and the angle at the pointy end angle is 4°. The height of the vertical (y) leg will be 0.5 * Sin(4). Rounded to three decimal places, that's 0.035". To check the error due to rounding, divide 0.035 by 0.5 and take the arcsin. You'll get 4.014°. More than close enough for jazz.

So, lock the cross-slide and set over the compound slide at 4° indicated and take a few cuts on a piece of scrap until you have a taper 1/2" long, there-abouts. Wind the compound slide back to the end of the work and set the collar to zero. Crank the saddle down the job manually to turn a short parallel piece about 1/8" long at the zero setting. Now carefully advance the taper using the compound slide, winding slowly and smoothly by hand for exactly 0.500" as indicated by the collar. Stop, then advance the saddle again to form another 1/8" of parallel turning.

Stop the lathe and measure the two parallel diameters accurately (a micrometer is better than a Vernier for this). Subtract the two readings and halve the result. If you are spot on, the result will be 0.035". But that is most unlikely and you will find the taper angle you set is too great (difference > 0.035), or too little (< 0.035). To correct this, you need to shift the set-over by half the error.

Let's say the taper was 0.005" too great (meaning the angle was 4.57°). Reset things so the tip of your tool is touching the larger parallel diameter. Unlock the cross slide and wind out 0.0025". Lock up again, unlock the compound angle and move the angle setting until the tool tip touches the larger parallel section. Lock up, and make another test section as before. If you can get the half diameter distance to within 0.0005" of 0.0350", you'll have an error of less than 0.05° (yes, the error will vary with the angle, but if you work to four decimal places with a micrometer, you will get very close quite quickly).

So now you have a way of forming quite an accurate angle without sophisticated measuring equipment and if you keep careful workshop notes of the reading achieved for the particular part on the particular day, resetting to the same precise angle in the future will be no trouble. Even better, by setting to a known, precise angle, you can cut tapers in either direction (towards headstock, or tailstock) that will mate closely.

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