Hi Guys - I'm somewhat taken aback and very pleasantly surprised at the depth of interest - I hope it will live up to your expectation. I can see you agree that it has a certain character and Les's version definitely oozes that Italian 'style'.
To respond to the points raised...
Simon - Yes it's 6082 over here too but I still think of it as the old HE30. I usually put the 6082 in brackets
Lovely stuff to machine particularly as, apart from the odd squirt of cutting fluid, I have to do most machining dry.
Danny M - No, it's a conventional set up - anti-clockwise. I think the image is misleading. I have several pics of original engines now all showing conventional props fitted. Incidentally while you are here - what is that lovely looking side port in your avatar?
Bill - I've not made anything from scratch smaller than 5cc however I have rebuilt and refurbished commercial engines down to 0.5cc. Given a good piston and crankcase seal there's not really that much difference though the smaller engines appear to like to be quite 'wet'. They need a faster rather than harder 'flick' to get the piston moving but apart from that not much else. Individual engines do have their own characteristics however and some can be real finger 'depleters'
The main thing I like about 5cc size is that the parts are not so small and fiddly as to make work holding awkward and not so big as to make material costs unreasonable.
Jo - further checking reveals that Travagli's Super Antares is dated 1944 same date as the Atomatic 4 and Vantini's Antares engines 42 onward. The 'Ato' 5 is dated 1947.
As hoped, swarf production got underway today but there's little to show save for two milled blocks and two bored holes. Here's a closer pic of the GA which may explain the build a bit better.
The blocks once milled weighed 368 gms - I wonder how much of that will disappear in the bin.
When I first drew this out I could not fathom why the case was cast with an integral back-plate which then had a hole in it. I decided to leave the plate out and make it a straight through bore. Something obviously fitted into the hole but it would be a while before I could make a guess based on a image on the net and one which, I'm certain, was confirmed recently on some drawings. I'm now convinced it is a crankcase pressure relief valve - no doubt intended to be used in conjunction with a timer to cut the engine on free flight models.
Bearing in mind the two blocks are primarily in case a boo boo occurs I have decided to do one as first drawn - without the integral plate - and the other as per the prototype. At this stage though major thoughts are with getting the areas around the exhaust stubs to look convincing - the rest will only follow once that has been achieved (says he hopefully).
I had an email from Sandy regarding the boiler burner and in which he comments on this engine. He wonders how the rotor disc will be kept in contact with the port face. This raises a good question and one which could be answered here.
Rear rotor discs are usually set with a small gap, usually 3-5 thou sometimes more, to prevent surface drag, the disc floating within this allowance and not being directly influenced back and forwards. Here though, even with a degree of end float on the shaft the prop thrust will always pull the rotor onto the port face unless the crankshaft forward movement is is restricted. I have set the rotor running on the crankshaft bearing sleeve which will protrude sufficient to give the required gap - the c'shaft web bearing directly on the end face. Not exactly a large surface, and one which may wear eventually but given that this will only be run - if indeed it does - on odd occasions it will hopefully be sufficient enough.
Well, that's it for tonight guys - a good book beckons
Ramon
