The Owen "Mate" 2cc Diesel
Created: Jan 4, 2001
Last update: Aug 16, 2007
|Production run||sold out||Country of Origin||Australia|
|Photo by||Ron C||Year of introduction||1989|
Here we have my attempt at the Owen Mate 2cc diesel. This engine was designed by noted Australian model engine authority, David Owen who hales from Wollongong, which is on the coast, just south of Sydney. The Mate was designed as a sport engine for first time constructors and is based on a unique (as far as I know) stroke-a-genius: the crankcase is an aluminum extrusion which has the cross section of the typical two stroke model engine. This section should be apparent in the accompanying photographs.
Is this a simpler approach than the traditional casting? No, I don't think so. A casting (usually) just requires a little cleaning up to remove any flash, or casting knobs, then it can be chucked and bored, etc. The extrusion on the other hand must be rough sawn to remove the part that doesn't look like a crankcase, then turned to external shape (requiring a fair amount of interrupted-cut type work) before the internal work can start.
So where's the advantage? Well, as I see it, David's approach has two very significant benefits. First, the casting of anything in small quantities is not commercially viable. I don't think any model engine kit supplier is in it to get rich, but break even would be nice and this approach let David make 'em by the mile and cut 'em off by the inch (or there abouts). As an aside, I believe it was the well known Australian icon, Ivor F (yup, that's his full name) who observed that the only sure way to make a small fortune manufacturing model engines was to start with a large one. Anyway, the second advantage is related to the porosity problem sometimes encountered with aluminum castings. It's never happened to me, but I can understand how discouraging it would be to spend hours carefully machining a crankcase only to find a defect discovered as work proceeds makes the casting unusable. Work done in home foundries (to avoid the cost/quantity viability problem) is particularly vulnerable to this, so most suppliers have a standard offer: you hit a bad casting, they replace free of charge. Certainly that's always been Roger Schroeder's philosophy. But it's better not to have to do this and with an extrusion, David is assured of uniform quality throughout the product.
The Mate is a standard, plain bearing, front rotary shaft induction, compression ignition engine. It has a steel crankshaft and cylinder liner with a cast iron piston and contra-piston. The venturi intake is added after the front of the case has been shaped and the bronze bearing pressed into place, being held in place by high temperature Locktight. David provides excellent drawings (metric) and a very cleaver machining sequence that would be difficult to foul up on in a non-recoverable way.
The kit contains everything needed to build the engine, right down to the prop nut (metric). It was produced for more than 10 years and sold here in Oz and in the USA (where it even comes with a nice little can of diesel fuel!). David is out of the extrusion now and will not be funding another production run, so if you want one, you'll have to chase it down elsewhere. The design however will continue to be available as part of the Motor Boys' Collection of Model IC Engine plans. This means though that you would have to hack a crankcase out of the solid (not as hard as it sounds), or try your hand at backyard foundry work.
My example started up right away (having already given a few kicks with a prime while held in the hand - I just can't wait). I don't have tach figures on it yet, but it swings a 10-6 wood happily and starts to scream a bit as the diameter comes down. This is not a workhorse engine that could be run all day, every weekend. But run occasionally for the club (or yourself) it will certainly haul a control line stunter like a Barnstormer, or a Kiel Kraft Spectre, or old time radio model around for many seasons - and look just great as a display piece in between.
During an impromptu meeting and wine-tasting held by the down-under chapter of The Motor Boys, David and I had the chance to put our two Mates together, posed for this shot. Mine is the one with the slightly larger prop nut thread. I went with the standard 1/4-28 rather than the funny metric thread called out in the plans .