Fig Tree Pocket Twin (oz13722)

About this Plan

Fig Tree Pocket Twin. Model aero diesel engine.

CAD drawings by Ron Chernich. Article by Ron Chernich.

Quote: "The Twin from Fig Tree Pocket, by Ron Chernich.

And just where, you may well ask, is 'Fig Tree Pocket' and why do twin cylinder diesels feel the need to escape from it? All good questions, well deserving of equally good answers. Fig Tree Pocket is a quiet, leafy outer suburb of Brisbane, itself the capitol and largest city of the state of Queensland, Australia. Within these pleasant surroundings may be found a gentleman of the old school and long time modeler, Mr Russell Watson-Will.

Russell, who is now retired, builds models and engines. Mostly aeronautical, but not always. A few years ago, like a sculptor, Russ regarded a large block of 2024-T4 aluminum and saw the twin cylinder diesel within, just waiting to be let out. The result is the engine detailed on the next few pages. Now it's well known that I'm a total sucker for twins. This is a personal failing I've come to terms with and even, dare I say, embraced. On seeing Russ's latest creation, I decided that even if I never built one, I simply had to have a set of drawings for it. All that remained was tricking Russ into agreeing.

Casually, I mentioned that this looked like a good choice for a Motor Boys plan set and perhaps he might allow me to take some measurements? I was saved from my having to execute my contingency plan (which involved a lot of embarrassing begging and groveling on bended knees) by Russ offering the loan of all the drawings he'd made during the design and his generous offer of help with any details that were not clear. As I said, Russ is one of nature's gentlemen.

On one point though, Russ was adamant; this was not his design. Eh? Wasn't it a one-of-a-kind engine? Yes. Hadn't he made it, from scratch? Yes. Then wasn't he, ipso facto, the designer? No. In his view, the general crankcase design was borrowed from the British 'Craftsman Twin'. The cylinders, pistons and porting were copied from a Czech MVVS diesel. The con-rod big end design was stolen from Edgar Westbury's 'Ladybird' twin in-line diesel (which Russ has made from the solid) and the use of reed valve induction for horizontal opposed twins was common practice. So there was simply no way, Russ emphasized, that he could, with any degree self-respect, present the engine as his! We agreed. I would CAD-ify the engine and attribute it to him with some appropriate weasel words that did not contain the phrase 'designed by.'

As the project came towards the end, I put 'Fig Tree Pocket Twin' in the title block and handed a set of drawing to Russ for him to cast his eagle eye over. Apart from pointing out a few minor matters such as the fact that the engine as I'd drawn it would not actually turn over, he approved the plans and, with a twinkle in his eye, even the name it had taken on.

The FTP Twin is a strong runner and started so readily that Russ nearly lost fingers in the surprise. Although it requires an advanced degree of experience in model engine building in order to work out the machining sequences and to know which parts need to be precisely aligned to minimize working friction, it is not an engine for master machinists only. It could be built by any model engineer who has made a diesel or two and understands which bits are critical. Even simply studying the drawings to see how Russ went about choosing just what should go into a horizontally opposed twin diesel is rewarding in itself. I leave it to you to decide if Russell is the designer, or simply the constructor of a beautiful, unique engine."

Direct submission to Outerzone.

Note this plan (and article) is an extract from the MBI (Motor Boys International) Model Engine Plan Book, 2nd Edition. This was originally published through the MEN site run by Ron Chernich, see http://www.modelenginenews.org/. Also see Mary's page on RCLibrary https://rclibrary.co.uk/title_details.asp?ID=2122 which hosts a copy of the book as submitted from MBI by Ken Croft, in accordance with Ron Chernich's wish that from 2013 onwards the book should be available, freely, to everyone as a PDF download.

Note photo [main pic] showing completed Fig Tree Pocket Twin shows engine built by Don Brymer (Australia).

Supplementary file notes

Article.

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