Hi all The question of prop hubs and taper vs. parallel fit is discussed on the Australian Aeropower web site at http://www.arach.net.au/~munks/AEmenu.htm. This company has been producing VW derivative aircraft engines since the early 1980s. I have not seen a more comprehensive engine site anywhere. It's also interesting to note that all of their aero engines are type-1 derivatives.
Here is an excerpt: <quote> Aeropower Engines decided against a tapered attachment flange in their design for several reasons: (a) The parallel flange can be used to retain the timing gears. Less work, less parts, less cost. (b) Parallelism is easy to measure. There is no need to lap mating faces and parts interchange easily. (c) Accidental overtorquing of the retaining bolt on a tapered flange can cause the flange to split or spread enough to cause a bearing clearance or oil rewind problem. (d) The reduced diameter at the nose of tapered cranks has been known to crack through to the front keyway, which then diminishes the effectiveness of the taper. (e) If a flange needs to be removed in the field it is very hard to stop oil getting onto the taper. The flange of the Aeropower Engines design can be removed or replaced in the field with simple hand tools, without dismantling the engine or risk of bending, distorting or misaligning the flange face. Since the grip of the flange does not rely on a taper, oil on the crankshaft is not a problem. <end> Phil Maley Perth Australia
