|Type||SOHC four-stroke, glowplug ignition||Capacity||14.7cc|
|Production run||Home Construction||Country of Origin||UK|
|Photo by||Nemett||Year of publication||2006|
As most readers should know, the venerable English magazine, [the] Model Engineer, has been in continuous publication since January, 1898. Over that period, the subject of internal combustion has made sporadic appearance, reflecting the interest of the readership, and the availability of contributors. However, when IC subjects have appeared, they have mostly been quite notable: the many designs and wisdom of ET Westbury, Lew Blackmore's brilliant BR2 Rotary, Eric Whittle's Aero V8, etc, etc. Recently, a new name has appeared in the pages of the ME to address the growing interest in IC projects (see Model Engine News for September, 2005). Following the fine ME tradition, the latest IC proponent writes under the nom de plume "Nemett".
Could be a coincidence.
The first construction series designed by Nemett commenced in issue 4273. As the ME publishes fortnightly, their common practice is to serialize over alternate issues, so the NE15S appears in odd numbered issues.
DescriptionThe photos and description that follows were provided by Nemett himself:
The NE15S is a single cylinder, single overhead cam shaft four stroke with air or water cooling options. The main parameters of the engine are:
|Length (including carb)||200mm|
|Height to top of cam box||165mm|
|Width (crank case)||63mm|
|Width across bearers||88mm|
|Cam shaft drive||Single 2.5mm pitch 6mm wide toothed belt.|
|Carburettor||Barrel type with adjustable fuel needle and slow running air bleed. Choke diameter 7mm.|
- 5,750 rpm on glow fuel
- 7,400 rpm on spark.
The 'exploded' view shows a few more features not mentioned in Nemett's brief overview. No castings are required; the engine is machined from bar-stock. There are no rocker arms; the cams act directly on hollow, cylindrical tappets that sit on top of the valve stems and provide tangetial contact with the cams. The crankcase vent appears to be connected to the OHV cavity by a small bore copper pipe. Drain plugs are fitted to the backplate and OHV cover suggesting this is a form of lubrication. I thought cases were vented to get rid of corrosive nitros oxide gas produced by blow-bye, but I'm sure our designer has a theory and an answer.
ConclusionThe large size of the engine and simple, straight forward construction will be appreciated by model engineers trying IC as a diversion from the usual ME fare of live steam. The NE15S would be a bit on the large size to screw into the nose of a flying model, but I've little doubt someone will do just that. Hopefully the experience of building and running the engine will decide many to follow up with other types, or even to produce designs of their own. Nemett and the Model Engineer are to be commended for this effort.